The Distance Between Galaxies Is Worse Than You Think

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Look at any photograph of the night sky taken by
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a powerful telescope. Galaxies appear everywhere. Spirals, ellipticals, irregular clouds
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of light scattered across the darkness like glowing islands in
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a cosmic sea. They look close together. They look like
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neighbours separated by manageable distances. That impression is one of
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the most dangerous lies in all of astronomy. The actual
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distance between galaxies is so enormous, so overwhelmingly empty, that
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it turns the universe into something far lonelier than any
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photograph suggests. Even our nearest large galactic neighbor sits so
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far away that light itself needs two and a half
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million years just to cross the gap, and between those
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galaxies lies almost nothing. A void so vast and so
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utterly barren that it redefines what the word isolation means.
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If you want to see why the space between galaxies
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is the most terrifying distance in the universe, do me
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a favor and consider tapping that like and subscribe button.
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It genuinely helps this channel keep making these deep dives
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and I really appreciate every single one of you who
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sticks around. Now settle in, get yourself comfortable. Let's begin.
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Open any astronomy book published in the last 30 years.
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Find the photographs taken by space telescopes pointed at the
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deepest reaches of the cosmos. You will see galaxies everywhere.
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Thousands of them packed into a single frame. Spirals tilted
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at elegant angles. Ellipticals glowing like golden lanterns. Irregular smudges
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of light scattered between larger structures, like cosmic confetti. The
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images are breathtaking. They are also profoundly misleading. When you
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look at a deep-field photograph from the Hubble Space Telescope
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or the James Webb Space Telescope, your brain does something
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automatic and dangerous. It treats the image as a kind
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of landscape. It sees galaxies positioned near each other on
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a flat plane and assumes they are neighbours. The way
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houses sit across a street, the way boats float in
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a harbour, your mind fills in the gaps with an
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assumption of proximity because that is what your visual system
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was built to do. Millions of years of evolution on
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the African savannah trained your brain to judge distances based
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on how objects appear relative to one another. Something that
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looks close must be close. Something positioned next to another
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object must be nearby. This instinct serves you well on Earth.
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It will betray you catastrophically when applied to the universe.
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Those galaxies you see clustered together in telescope images are
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not clustered at all. They are separated by distances so
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enormous that the word distance barely applies. Many of them
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sit millions of light years apart. Some are separated by
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tens of millions, others by hundreds of millions. A few
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are billions of light years from their apparent neighbours in
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the frame. The photograph compresses all of this depth into
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a flat image, and your brain does the rest, collapsing
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inconceivable gulfs into the cosy illusion of a crowded room.
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Consider the Hubble Ultra Deep Field, one of the most
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famous astronomical images ever taken. Astronomers pointed the telescope at
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a tiny patch of sky, a patch so small you
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could cover it with a grain of sand held at
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arm's length, and kept the shutter open for 11 days.
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The resulting image revealed over 10,000 galaxies in that single
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minuscule sliver of sky. 10,000 galaxies crammed into a frame
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smaller than a fingernail held against the night. Your eye
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sees density. Your brain sees neighbours, but many of those
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galaxies are separated by billions of light years of empty space.
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Some existed when the universe was less than a billion
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years old. Others are relatively nearby, only a few hundred
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million light years distant. The image flattens all of this
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cosmic depth into a mosaic that looks like a crowded
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jewel box, and the lie becomes almost irresistible. You would
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never guess, looking at that image, that the dominant feature
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of the universe it depicts is not the galaxies but
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the emptiness between them. This is not a minor misunderstanding.
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This is the single most dangerous optical lie in all
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of astronomy. It makes you believe the universe is full
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in a way that implies connection. It makes you feel
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that galaxies are scattered like stars across a sky, separated
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by manageable distances, reachable in principle if not in practice.
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The truth is the opposite. Galaxies are among the most
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isolated structures in existence. The voids between them are so
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vast and so empty that even neighbouring galaxies exist in
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a kind of cosmic solitary confinement. And the scale of
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that separation is something most people never confront, because every
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image they have ever seen was designed, unintentionally, to hide it.
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To understand why intergalactic distances are so terrifying, you first
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need to understand what a galaxy actually is, not as
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a word, not as a glowing shape in a photograph,
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but as a physical object with a real size that
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already exceeds anything the human mind can comfortably hold. Our galaxy,
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the Milky Way, is a barred spiral containing somewhere between
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200 billion and 400 billion stars. Current estimates lean toward
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the higher end of that range. Each of those stars
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is a thermonuclear furnace, many of them orbited by planets, moons,
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asteroids and comets. The entire structure spans roughly 100,000 to 200,000
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light years from edge to edge, depending on how you
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define the boundary. Some measurements that include the faint outer
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stellar halo and the dark matter envelope push that number
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even higher. For the purposes of understanding intergalactic distance, even
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the conservative figure is staggering enough. 100,000 light years means
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that a beam of light, travelling at 186,000 miles per second,
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the fastest speed permitted by the laws of physics, you
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would need 100,000 years to cross from one side of
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our galaxy to the other. That single fact should stop
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you cold. Light is not slow. It crosses the distance
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from the Earth to the Moon in about one and
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a quarter seconds. It reaches the Sun in roughly eight minutes.
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It passes the orbit of Neptune in about four hours.
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It passes the orbit of Pluto in about five and
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a half hours. Yet this same light, moving at the
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absolute cosmic speed limit, would need 100,000 years to traverse
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the structure you live inside. When the light now arriving
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from the far edge of the Milky Way began its journey,
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modern humans had not yet left Africa. Entire civilizations have
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risen and fallen in the time it takes a single
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photon to cross our galactic home. The Milky Way is
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so large that the speed of light, the fastest thing
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in the entire universe, is too slow to cross it
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in anything resembling a human lifetime. It is too slow
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to cross it in a thousand human lifetimes. It would
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need roughly 1300 human lifetimes, end to end, just to
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make the trip. This is the scale of a single galaxy,
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one structure, one island of stars. and you need to
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hold this scale firmly in your mind, because it is
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the ruler against which intergalactic distances must be measured. Whatever
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number you are about to hear for the gap between galaxies,
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remember that the galaxy itself is already absurdly, incomprehensibly large.
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The distance between galaxies is not measured in miles or
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even in light-years the way we measure planetary or stellar distances.
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It is measured in multiples of galaxy lengths. And when
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you realise how large a single galaxy length already is,
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the multiples become devastating. Now look up on a clear
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autumn night from the northern hemisphere. Find the constellation Andromeda.
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Locate the faint, hazy smudge of light that sits just
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off the chain of stars marking the constellation boundary. That
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smudge is the Andromeda galaxy. It is the most distant
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object visible to the unaided human eye. It appears small,
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It appears faint. It appears manageable. It is none of
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these things. The Andromeda Galaxy is a monster. It contains
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approximately one trillion stars. Its disk stretches across roughly 200,000
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to 260,000 light-years, making it comparable in size to our
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own Milky Way, and possibly somewhat larger. In January of 2025,
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NASA released a stunning mosaic of Andromeda, assembled from over
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600 overlapping Hubble Space Telescope observations taken across a decade
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of work. That mosaic resolved approximately 200 million individual stars,
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and it still captured only a fraction of the galaxy's
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total stellar population. Andromeda is a gravitational empire containing thousands
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of star clusters, billions of planetary systems, and a supermassive
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black hole at its centre with a mass exceeding 100
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million times that of our Sun. It is not a
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small neighbour, it is a full-scale galactic civilisation sitting across
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the void from us, and it is approximately 2.5 million
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light-years away. Say that number slowly, 2.5 million light-years. Let
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your mind try to process what that means in physical terms.
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A light year is roughly six trillion miles. Multiply six
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trillion by two and a half million and you arrive
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at a distance of approximately 15 quintillion miles. That number
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has so many zeros it stops being a number and
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becomes an abstraction. So let me bring it closer to
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something you can feel. The Parker Solar Probe, which in
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December of 2024 became the fastest human-made object in history,
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reached a speed of approximately 430,000 miles per hour as
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it swung past the Sun. At that speed, you could
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travel from New York to Tokyo in under a minute.
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You could circle the entire Earth in about three and
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a half minutes. This is the pinnacle of human velocity,
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the absolute fastest any machine built by our species has
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ever moved. At the speed of the Parker Solar Probe,
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the journey to the Andromeda Galaxy would take approximately 4
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billion years. Not 4,000. Not 4 million. 4 billion. That
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is roughly the current age of the Earth. You would
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need to travel at the fastest speed humanity has ever achieved,
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without stopping, without slowing, for a duration equal to the
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entire geological history of our planet, just to cross the
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gap between two galaxies that astronomers describe as neighbours. Even light...
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The ultimate cosmic messenger needs two and a half million years.
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If you could somehow freeze the Andromeda galaxy in time
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and fire a laser beam at it right now, the
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photons would not arrive until two and a half million
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years from now. By the time that signal reached the
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other side, whatever civilization sent it would almost certainly be
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unrecognizable or extinct. The gap is not just far. It
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is temporally ruinous. It destroys any hope of timely communication.
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let alone physical travel. And here is the part that
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truly breaks intuition. Andromeda is close. By galactic standards, it
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is practically next door. It is the nearest large spiral
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galaxy to our own. When astronomers talk about nearby galaxies,
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Andromeda is the first name they mention. It is our
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most immediate peer, our closest gravitational partner, the galaxy most
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likely to interact with us in the future. In roughly
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5 to 7 billion years, Andromeda and the Milky Way
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are expected to collide and merge into a single massive
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elliptical galaxy, though recent studies place the probability at somewhere
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between 50 and 90 percent, depending on the gravitational influence
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of other local group members. They are already approaching each
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other at approximately 250,000 miles per hour. This is not
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a distant hypothetical. It is a confirmed trajectory. measured through
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decades of spectroscopic observation. Two galactic empires, each spanning hundreds
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of thousands of light years, each containing hundreds of billions
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of stars, are locked in a slow gravitational embrace that
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has been tightening for billions of years. And the gap
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between them is still so enormous that their approach speed,
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impressive as it sounds, barely registers against the distance remaining.
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Yet even this galaxy, this neighbour, this partner, on a
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confirmed collision course with our own home, sits so far
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away that light needs two and a half million years
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to bridge the distance. The photons entering your eye when
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you look at that faint smudge in the autumn sky
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left Andromeda's stars before the genus Homo existed on Earth.
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You are not seeing a galaxy as it is now.
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You are seeing a ghost, an image frozen in deep time,
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delivered across a void so wide that the entire history
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of human evolution fits comfortably inside the transit. Every step
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our ancestors took out of Africa, every language they invented,
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every empire they built and lost, every war they fought,
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every scientific revolution they sparked, all of it happened while
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those photons were still in transit, still crossing the emptiness
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between here and there. An Andromeda is just one member
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of our local galactic family. The Milky Way belongs to
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a gravitational association called the Local Group, a collection of
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galaxies bound together by their mutual gravitational attraction. As of
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the most recent surveys, the Local Group contains approximately 134
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confirmed members. That might sound like a dense neighbourhood. It
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is not. The vast majority of those members are tiny
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dwarf galaxies containing only a few billion or even a
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few million stars each. Many of them orbit the Milky
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Way or Andromeda as satellites, trapped in gravitational bondage like
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moons circling a planet. The third largest member, the Triangulum Galaxy,
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contains roughly 40 billion stars and sits about 2.7 million
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light-years from us. Beyond these three dominant spirals, The local
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group is mostly populated by dim, small, easily overlooked structures
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scattered across a volume of space, roughly 10 million light
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years in diameter. 10 million light years. That is the
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size of our so-called neighbourhood. The distance across the local group,
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from one edge to the other, is approximately 100 times
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the diameter of the Milky Way itself. Imagine standing in
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your house and being told that the nearest house is
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100 house lengths away, not 100 feet, 100 times the
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size of your entire home. That is the kind of
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spacing we are talking about, and this is the densest
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galactic environment anywhere near us. Within this vast volume, galaxies
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are not evenly distributed. They clump around the two gravitational anchors,
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the Milky Way and Andromeda, with a loose scattering of
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dwarfs filling the space between. Some of those dwarfs are
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so faint and so isolated, that astronomers are still discovering them.
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A revised three-dimensional map of the local group, published in
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late 2025, catalogued 142 confirmed members and noted that discoveries
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continue at a steady pace, particularly of ultra-faint dwarf galaxies,
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hiding in the data from surveys like Gaia and the
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James Webb Space Telescope. The group's overall structure resembles a dumbbell,
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with one lobe of galaxies centred on the Milky Way
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and another centred on Andromeda, separated by roughly two and
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a half million light-years of nearly empty space. Between those
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two lobes, a sparse scattering of isolated dwarfs drifts through
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the gravitational field of both giants, too small to anchor
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their own communities and too far from either centre to
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feel truly at home. The space connecting those two lobes
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is not a bridge, it is a gulf. a region
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of near total emptiness that even the gravitationally bound members
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of this family must cross over timescales measured in billions
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of years. But here is the crucial thing about the
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local group that most people never consider. Even inside this
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gravitationally bound family, the distances between members are enormous. The
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Large Magellanic Cloud, one of the closest satellite galaxies to
258
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the Milky Way, sits roughly 160,000 light-years away. The small
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00:17:18.109 --> 00:17:22.490
Magellanic Cloud is about 200,000 light years distant. These are
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satellites of our own galaxy, gravitationally bound to us, orbiting
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within our extended halo, and they are still so far
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away that light needs hundreds of thousands of years to
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make the trip. The Sagittarius dwarf elliptical galaxy is closer,
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only about 70,000 light years from our galactic centre, but
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it is in the process of being torn apart by
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the Milky Way's tidal forces. It is not a neighbour
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so much as a victim, a galaxy being consumed by
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our own. Step beyond the satellites and the gaps widen dramatically.
269
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The next nearest significant galaxies after the Magellanic Clouds and
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the various dwarf satellites are objects like NGC 6822, an
271
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irregular galaxy roughly 1.6 million light-years away, and IC 1613.
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another irregular galaxy at about 2.4 million light years. These
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00:18:18.289 --> 00:18:23.150
are small systems, faint and unremarkable in cosmic terms, and
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they already sit at distances that make any concept of
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00:18:26.210 --> 00:18:29.950
physical connection meaningless. A beam of light sent from the
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Milky Way to IC 1613 would arrive after 2.4 million years.
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A spacecraft travelling at the Parker Solar Probe's record speed
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would need roughly 4 billion years. These galaxies are our neighbours,
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part of our own gravitationally bound family, and reaching them
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is already functionally impossible. What people rarely grasp is how
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empty the space between these galaxies actually is. When you
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look at a map of the local group, the galaxies
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00:18:59.230 --> 00:19:02.589
appear as labelled dots on a diagram. Your brain treats
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the diagram the same way it treats a roadmap. It
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00:19:05.730 --> 00:19:10.230
sees dots connected by implied roots. It assumes the space
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00:19:10.269 --> 00:19:15.500
between the dots is filled with something. Roads, terrain, atmosphere, medium.
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00:19:16.359 --> 00:19:19.119
But the space between galaxies is not filled with anything
288
00:19:19.200 --> 00:19:22.950
resembling a medium. It is filled with almost nothing. The
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00:19:22.970 --> 00:19:27.230
interstellar space within our galaxy, the space between stars, is
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00:19:27.269 --> 00:19:32.069
already extraordinarily empty. A typical region of interstellar space contains
291
00:19:32.150 --> 00:19:36.680
roughly one million hydrogen atoms per cubic metre. That sounds
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00:19:36.720 --> 00:19:38.839
like a lot until you compare it to the air
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00:19:38.859 --> 00:19:43.319
you are breathing right now, which contains approximately 25 trillion
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00:19:43.400 --> 00:19:47.950
trillion molecules per cubic meter. Interstellar space is a vacuum
295
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so profound that no laboratory on Earth has ever come
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00:19:51.490 --> 00:19:55.210
close to replicating it. And yet, compared to the space
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00:19:55.250 --> 00:20:01.839
between galaxies, interstellar space is practically dense. Intergalactic space contains
298
00:20:01.900 --> 00:20:06.779
approximately one atom per cubic metre. One. In a volume
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00:20:06.819 --> 00:20:09.599
of space the size of a washing machine, you would
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00:20:09.640 --> 00:20:15.700
find a single hydrogen atom. The rest is void. Pure, featureless,
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00:20:16.200 --> 00:20:20.819
uninterrupted nothingness stretching for millions of light years in every direction.
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00:20:21.180 --> 00:20:24.700
The intergalactic medium, as astronomers call it, is one of
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00:20:24.740 --> 00:20:28.930
the most rarefied environments in the known universe. According to
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00:20:29.009 --> 00:20:33.589
measurements from the Harvard-Smithsonian Center for Astrophysics, this material has
305
00:20:33.630 --> 00:20:37.210
a density less than a billionth of a billionth of
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00:20:37.250 --> 00:20:40.099
the density of air at sea level. That is not
307
00:20:40.220 --> 00:20:44.269
emptiness in the casual sense. That is emptiness so extreme
308
00:20:44.329 --> 00:20:48.289
it challenges the meaning of the word exist. Intergalactic space
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00:20:48.690 --> 00:20:52.650
is roughly one million times emptier than the space between stars.
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That is not a gradual increase. That is a chasm.
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If interstellar space is a desert, intergalactic space is a
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00:21:01.539 --> 00:21:03.700
desert the size of a continent with nothing in it
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00:21:03.740 --> 00:21:07.279
but a single grain of sand. The jump from interstellar
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00:21:07.319 --> 00:21:10.200
to intergalactic is not a step up the same ladder.
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00:21:10.980 --> 00:21:14.259
It is a leap to a completely different category of emptiness,
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00:21:15.019 --> 00:21:18.480
a void so extreme that it severs any physical or
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00:21:18.549 --> 00:21:22.750
intuitive connection between the structures it separates. Think about what
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00:21:22.809 --> 00:21:26.450
that density means in practical terms. If you could somehow
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00:21:26.609 --> 00:21:29.359
scoop up all the matter in a cube of intergalactic
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00:21:29.430 --> 00:21:33.059
space one million kilometers on a side, a cube large
321
00:21:33.099 --> 00:21:36.509
enough to swallow our sun several times over, you would
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00:21:36.549 --> 00:21:39.230
collect a quantity of material so small it would be
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00:21:39.269 --> 00:21:43.309
invisible to the naked eye. The void between galaxies is
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00:21:43.369 --> 00:21:47.490
not just empty. It is a near-perfect vacuum, on a
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00:21:47.589 --> 00:21:52.200
scale that dwarfs anything in human experience. The best vacuum
326
00:21:52.259 --> 00:21:55.559
chambers on Earth, the ones used in semiconductor fabrication and
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00:21:55.599 --> 00:22:00.539
particle physics, contain roughly 10 trillion molecules per cubic meter.
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00:22:01.559 --> 00:22:06.390
Intergalactic space is 10 trillion times emptier than that. It
329
00:22:06.450 --> 00:22:09.430
is a void so thorough that it barely qualifies as
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00:22:09.509 --> 00:22:12.470
part of the physical universe. And the temperature of this
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00:22:12.549 --> 00:22:17.829
void does not help. The intergalactic medium, despite containing almost nothing,
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00:22:18.490 --> 00:22:23.579
registers temperatures of millions of degrees. This sounds contradictory, until
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00:22:23.619 --> 00:22:27.119
you understand that temperature in physics describes the average kinetic
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00:22:27.200 --> 00:22:31.420
energy of particles, not how hot something would feel. With
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00:22:31.500 --> 00:22:35.000
so few particles per cubic meter, there is no meaningful
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00:22:35.059 --> 00:22:39.279
transfer of heat. You could float in intergalactic space and
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00:22:39.400 --> 00:22:42.680
freeze to death surrounded by particles technically hotter than the
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00:22:42.740 --> 00:22:47.099
surface of the Sun. The void between galaxies is simultaneously
339
00:22:47.220 --> 00:22:53.769
scorching and frozen, energetic and lifeless, technically filled and practically empty.
340
00:22:54.589 --> 00:22:57.190
It is a place where the normal categories of physical
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00:22:57.250 --> 00:23:01.890
experience break down entirely, where the concepts of hot and cold,
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00:23:02.029 --> 00:23:06.079
full and empty, lose their intuitive meanings and become technical
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00:23:06.140 --> 00:23:09.910
labels applied to conditions no human was ever meant to encounter.
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00:23:10.569 --> 00:23:13.890
This is the environment that separates every galaxy from every
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00:23:13.970 --> 00:23:18.569
other galaxy. Not a corridor. Not a passage. Not a
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00:23:18.630 --> 00:23:22.349
medium through which you could travel with sufficient technology. A
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00:23:22.450 --> 00:23:26.009
wasteland of such staggering emptiness that it makes the vacuum
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00:23:26.029 --> 00:23:29.900
between stars look like a crowded marketplace by comparison. and
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00:23:29.920 --> 00:23:33.180
this wasteland extends for millions of light years between even
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the closest galactic neighbours. The reason this matters, the reason
351
00:23:37.539 --> 00:23:40.750
it transforms intergalactic distance from a number into a horror,
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00:23:41.329 --> 00:23:44.190
is that the emptiness changes the nature of the separation.
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00:23:44.829 --> 00:23:47.930
When we talk about distances within our galaxy, we are
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00:23:47.950 --> 00:23:51.400
talking about gaps between objects embedded in a shared structure.
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00:23:52.480 --> 00:23:55.460
Stars within the Milky Way are part of the same
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00:23:55.539 --> 00:24:00.220
gravitational system. They orbit the same centre. They are embedded
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00:24:00.259 --> 00:24:04.440
in the same interstellar medium, the same magnetic fields, the
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00:24:04.460 --> 00:24:08.980
same cosmic ray environment. A journey between two stars within
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00:24:09.059 --> 00:24:15.690
our galaxy is a journey through something. Thin, sparse, unimaginably diffuse,
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00:24:16.170 --> 00:24:20.970
but something. There is a continuity between origin and destination.
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00:24:21.450 --> 00:24:25.950
They belong to the same place. Intergalactic space severs that
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00:24:26.029 --> 00:24:30.369
continuity completely. The gap between the Milky Way and Andromeda
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00:24:30.450 --> 00:24:33.849
is not a long hallway connecting two rooms. It is
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00:24:33.890 --> 00:24:37.609
an ocean with no water. There is no shared structure,
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00:24:38.289 --> 00:24:42.549
no continuous medium, no gravitational bridge you can follow from
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00:24:42.710 --> 00:24:46.609
one galaxy to the next. The galaxies float in isolation,
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00:24:47.150 --> 00:24:50.460
separated by voids so absolute that the word between barely
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00:24:50.519 --> 00:24:54.279
captures the reality. It is not the space between two things,
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00:24:54.759 --> 00:24:57.180
it is the absence of anything connecting them at all.
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00:24:58.009 --> 00:25:01.079
And this is the Local Group. This is the tightest,
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00:25:01.180 --> 00:25:06.000
most gravitationally intimate galactic association anywhere in our cosmic vicinity.
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00:25:06.700 --> 00:25:11.940
These galaxies are bound to one another. They will eventually interact, merge,
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00:25:12.470 --> 00:25:16.690
reshape one another through gravitational forces playing out over billions
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00:25:16.750 --> 00:25:19.990
of years. If any galaxies in the universe can be
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00:25:20.009 --> 00:25:24.589
called connected, it is these. And yet even here, Even
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00:25:24.650 --> 00:25:28.069
among gravitational partners confirmed to be falling toward each other,
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00:25:28.670 --> 00:25:31.829
the distances are so large and the voids so absolute
378
00:25:32.349 --> 00:25:36.450
that the concept of proximity loses all human meaning. Now
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00:25:36.509 --> 00:25:39.529
consider what lies beyond. The local group is not the
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00:25:39.569 --> 00:25:42.930
end of the story, it is the beginning. The nearest
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00:25:43.029 --> 00:25:46.740
galaxy cluster of any significant size is the Virgo Cluster,
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00:25:47.400 --> 00:25:52.049
sitting roughly 54 million light-years away. That distance is more
383
00:25:52.069 --> 00:25:55.410
than 20 times the gap between the Milky Way and Andromeda.
384
00:25:56.170 --> 00:26:01.039
Beyond Virgo lie other clusters, other superclusters, other walls and
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00:26:01.119 --> 00:26:04.940
filaments of galaxies stretching across hundreds of millions and billions
386
00:26:04.980 --> 00:26:10.059
of light-years. The observable universe contains an estimated 2 trillion
387
00:26:10.099 --> 00:26:15.400
galaxies spread across 93 billion light-years of cosmic diameter. And
388
00:26:15.420 --> 00:26:19.569
between all of those galaxies, threading through every gap, filling
389
00:26:19.789 --> 00:26:26.119
every void, lies the same intergalactic wasteland, the same near-perfect vacuum,
390
00:26:26.819 --> 00:26:31.119
the same atoms per cubic meter desolation stretching to horizons
391
00:26:31.180 --> 00:26:33.849
that light itself has not yet had time to reach.
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00:26:34.269 --> 00:26:38.109
The photographs lied to you. The universe is not crowded,
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00:26:38.650 --> 00:26:42.029
it is not full, it is not a bustling metropolis
394
00:26:42.069 --> 00:26:46.619
of galaxies scattered across a navigable space. It is a
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00:26:46.740 --> 00:26:50.539
scattering of isolated islands separated by oceans so wide and
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00:26:50.599 --> 00:26:53.420
so empty that the islands might as well exist in
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00:26:53.500 --> 00:26:57.369
separate realities. The galaxies are there. You can see them.
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00:26:58.029 --> 00:27:01.329
You can photograph them. You can count them in the trillions.
399
00:27:02.089 --> 00:27:04.769
But the space between them turns every one of those
400
00:27:04.829 --> 00:27:08.730
galaxies into a prisoner of its own location, surrounded by
401
00:27:08.750 --> 00:27:12.859
a void so vast that even light, the fastest messenger
402
00:27:12.900 --> 00:27:16.420
in the cosmos, needs millions of years to carry a
403
00:27:16.579 --> 00:27:20.059
single photon from one shore to another. And what makes
404
00:27:20.119 --> 00:27:23.700
this truly terrifying is not the distance itself. It is
405
00:27:23.740 --> 00:27:27.819
what the distance implies. If the nearest major galaxy is
406
00:27:27.880 --> 00:27:30.880
already two and a half million light years away, across
407
00:27:30.900 --> 00:27:34.529
a void containing one atom per cubic metre, then what
408
00:27:34.569 --> 00:27:38.529
does closeness even mean at this scale? What does neighbourhood mean?
409
00:27:39.230 --> 00:27:42.289
What does connection mean? The Local Group is the most
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00:27:42.349 --> 00:27:46.430
connected galactic environment we know, and its members are already
411
00:27:46.569 --> 00:27:51.430
so far apart that no signal, no spacecraft, no technology
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00:27:51.490 --> 00:27:55.150
conceivable under current physics could bridge the gaps within any
413
00:27:55.230 --> 00:27:59.759
meaningful timeframe. The universe did not scatter its galaxies carelessly.
414
00:28:00.460 --> 00:28:03.339
It arranged them in a pattern of isolation so extreme
415
00:28:03.759 --> 00:28:07.599
that even their gravitational partnerships play out across timescales measured
416
00:28:07.640 --> 00:28:11.230
in billions of years. The Milky Way and Andromeda are
417
00:28:11.269 --> 00:28:15.049
falling toward each other right now, confirmed and measured beyond
418
00:28:15.130 --> 00:28:18.049
any doubt, and they still will not meet for billions
419
00:28:18.089 --> 00:28:22.230
of years more despite already being locked in mutual gravitational attraction.
420
00:28:22.950 --> 00:28:26.910
Two galaxies that the universe itself has bound together, two
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00:28:26.990 --> 00:28:30.950
structures actively collapsing toward one another under the pull of
422
00:28:31.049 --> 00:28:34.329
mutual gravity, and they are still so far apart that
423
00:28:34.369 --> 00:28:37.369
their reunion will outlast the remaining life of our sun.
424
00:28:37.809 --> 00:28:41.099
That is the first shock, Galaxies that we call neighbours,
425
00:28:41.559 --> 00:28:45.859
galaxies visibly approaching one another, galaxies that may well collide,
426
00:28:46.460 --> 00:28:49.660
are still separated by chasms so wide that their merger
427
00:28:49.700 --> 00:28:52.329
requires more time than our star has left to burn.
428
00:28:53.049 --> 00:28:56.269
But the true emptiness between them, the nature of that void,
429
00:28:56.690 --> 00:28:59.450
the absence of anything filling the space they must cross,
430
00:29:00.109 --> 00:29:03.519
that is a story with far darker implications than most
431
00:29:03.559 --> 00:29:07.319
people are prepared to confront. And it begins with understanding
432
00:29:07.380 --> 00:29:10.839
what intergalactic space actually is, not as a concept on
433
00:29:10.880 --> 00:29:14.420
a diagram, not as a blank stretch on an artist's rendering,
434
00:29:15.019 --> 00:29:19.299
but as a physical environment more hostile, more barren, and
435
00:29:19.339 --> 00:29:22.140
more overwhelmingly empty than most people have ever been asked
436
00:29:22.160 --> 00:29:26.950
to imagine. So the distances have been established. Now forget
437
00:29:27.009 --> 00:29:31.789
the numbers. Forget the light years and the quintillions of miles. Instead,
438
00:29:32.289 --> 00:29:35.650
imagine you are there. You have been transported to a
439
00:29:35.730 --> 00:29:40.069
point in space exactly halfway between the Milky Way and
440
00:29:40.089 --> 00:29:43.829
the andromeda galaxy roughly one and a quarter million light
441
00:29:43.849 --> 00:29:47.430
years from either shore you float in your suit your
442
00:29:47.470 --> 00:29:51.000
instruments work your eyes adjust and what you see is
443
00:29:51.059 --> 00:29:55.140
nothing not nothing in the poetic sense not nothing in
444
00:29:55.180 --> 00:29:59.720
the way a dark room feels empty genuine structural nothing
445
00:30:00.390 --> 00:30:04.910
There are no stars, not one. The nearest individual star
446
00:30:04.970 --> 00:30:07.490
in any direction is so far away that its light
447
00:30:07.569 --> 00:30:10.609
is too faint to register, even as a dim point.
448
00:30:11.390 --> 00:30:13.829
The Milky Way behind you would appear as a pale,
449
00:30:13.950 --> 00:30:18.049
hazy smudge, a ghostly oval smaller than your thumbnail held
450
00:30:18.109 --> 00:30:22.490
at arm's length. Andromeda ahead would look similar, a faint
451
00:30:22.650 --> 00:30:27.150
grey glow with no resolved detail. Between those two smudges,
452
00:30:27.630 --> 00:30:30.829
in every other direction you look, The sky is black.
453
00:30:31.450 --> 00:30:34.390
Not the comfortable darkness of a clear night on Earth
454
00:30:34.450 --> 00:30:40.250
where thousands of stars provide a canopy of light. An absolute, featureless,
455
00:30:40.829 --> 00:30:46.519
unyielding blackness that extends in every direction without interruption. No nebulae,
456
00:30:47.160 --> 00:30:52.079
no star clusters, no comets or planets, no milky band
457
00:30:52.119 --> 00:30:56.240
of galactic light. Just the void. Your instruments confirm what
458
00:30:56.259 --> 00:31:00.569
your eyes already suspect. There is functionally nothing here. The
459
00:31:00.609 --> 00:31:05.029
material surrounding you is so sparse that your senses register
460
00:31:05.089 --> 00:31:09.039
it as indistinguishable from a perfect vacuum. You could extend
461
00:31:09.079 --> 00:31:11.640
your arms in every direction and sweep through a volume
462
00:31:11.680 --> 00:31:14.460
of space larger than a building without your gloves touching
463
00:31:14.500 --> 00:31:18.539
a single atom. The loneliness of this place is not metaphorical.
464
00:31:19.160 --> 00:31:22.589
It is physical. It is baked into the atomic structure
465
00:31:22.630 --> 00:31:25.269
of the space itself. You are floating in the most
466
00:31:25.349 --> 00:31:29.329
desolate environment the universe can produce. and it stretches outward
467
00:31:29.369 --> 00:31:31.809
from your position for over a million light years in
468
00:31:31.890 --> 00:31:36.609
every direction before anything resembling structure begins to emerge. This
469
00:31:36.670 --> 00:31:40.740
is not a theoretical exercise. The conditions are real. If
470
00:31:40.779 --> 00:31:43.839
you could somehow survive the journey and arrive at this midpoint,
471
00:31:44.240 --> 00:31:47.400
the visual experience would be unlike anything a human being
472
00:31:47.440 --> 00:31:51.849
has ever confronted. On Earth, even in the darkest desert
473
00:31:51.930 --> 00:31:55.069
on the darkest night, your eyes can detect the Milky
474
00:31:55.109 --> 00:31:58.549
Way overhead, a faint band of combined starlight from billions
475
00:31:58.609 --> 00:32:03.509
of suns. In intergalactic space, that band is gone. There
476
00:32:03.549 --> 00:32:06.650
is no ambient glow from any direction except the two
477
00:32:06.769 --> 00:32:11.769
faint smudges of the galaxies themselves. The cosmic microwave background radiation,
478
00:32:12.170 --> 00:32:15.529
the faint afterglow of the Big Bang, permeates the space
479
00:32:15.609 --> 00:32:18.890
around you. But its wavelength is far too long for
480
00:32:18.950 --> 00:32:22.619
human eyes to detect. As far as your senses are concerned,
481
00:32:23.170 --> 00:32:26.430
You exist in a darkness more complete than anything that
482
00:32:26.470 --> 00:32:30.470
occurs naturally on any planet orbiting any star. You could
483
00:32:30.509 --> 00:32:34.190
wait a billion years in this location and nothing would change.
484
00:32:35.089 --> 00:32:38.410
No star would drift close enough to become visible. No
485
00:32:38.509 --> 00:32:42.420
nebula would form. No light would appear. The void is
486
00:32:42.500 --> 00:32:47.640
patient and permanent. This is intergalactic space. Not a gap.
487
00:32:48.279 --> 00:32:53.009
Not a pause between interesting things. A place. an environment
488
00:32:53.049 --> 00:32:56.710
with its own physical properties, its own character, its own
489
00:32:56.789 --> 00:33:02.119
terrifying identity. And understanding what this place actually is, understanding
490
00:33:02.160 --> 00:33:05.000
what fills it and what does not, is the key
491
00:33:05.039 --> 00:33:09.480
to grasping why the distance between galaxies is not merely large,
492
00:33:10.000 --> 00:33:14.329
but qualitatively different from any other kind of cosmic separation.
493
00:33:15.130 --> 00:33:18.309
The intergalactic medium is not truly empty in the absolute sense.
494
00:33:18.940 --> 00:33:22.960
Physicists discovered decades ago that the space between galaxies contains
495
00:33:23.019 --> 00:33:27.589
a thin, diffuse material spread across the cosmic volume. This
496
00:33:27.670 --> 00:33:32.009
material has a name, the warm-hot intergalactic medium, and it
497
00:33:32.089 --> 00:33:35.730
is one of the most elusive substances in the observable universe.
498
00:33:36.190 --> 00:33:41.349
Cosmological simulations predicted its existence long before anyone detected it directly.
499
00:33:42.089 --> 00:33:45.710
The models showed that as the universe evolved and galaxies formed,
500
00:33:46.230 --> 00:33:49.839
Enormous quantities of ordinary matter should have been shock-heated during
501
00:33:49.859 --> 00:33:54.119
the process of gravitational collapse. Gas falling toward the dense
502
00:33:54.220 --> 00:33:57.440
regions of the cosmos would slam into other infalling gas
503
00:33:57.500 --> 00:34:01.900
at tremendous speeds, generating shockwaves that heated the material to
504
00:34:01.940 --> 00:34:07.089
temperatures between 100,000 and 10 million degrees. This heated plasma
505
00:34:07.130 --> 00:34:10.369
would then settle into the filamentary structure of the cosmic web,
506
00:34:10.929 --> 00:34:15.739
threading between galaxies in vast, tenuous streams. Too hot to
507
00:34:15.800 --> 00:34:20.320
form stars, and too diffuse to glow visibly. For years,
508
00:34:20.380 --> 00:34:24.360
this material was essentially missing. Astronomers could account for the
509
00:34:24.530 --> 00:34:29.469
ordinary matter locked inside galaxies, inside stars, inside planets and
510
00:34:29.550 --> 00:34:33.349
gas clouds. They could measure the matter in galaxy clusters,
511
00:34:33.869 --> 00:34:37.050
where hot gas glows in X-rays. But when they added
512
00:34:37.110 --> 00:34:40.420
it all up, roughly half the ordinary matter the universe
513
00:34:40.460 --> 00:34:44.309
should contain was unaccounted for. The numbers from the cosmic
514
00:34:44.369 --> 00:34:48.690
microwave background, the afterglow of the Big Bang, told scientists
515
00:34:48.769 --> 00:34:52.829
exactly how much normal matter the universe produced. The numbers
516
00:34:52.869 --> 00:34:55.920
from direct observation told them where only about half of
517
00:34:55.980 --> 00:34:59.059
it ended up. The rest had vanished into the void
518
00:34:59.119 --> 00:35:03.420
between galaxies. The warm, hot intergalactic medium was the answer.
519
00:35:03.900 --> 00:35:08.679
In 2018... Observations of highly ionized oxygen atoms in the
520
00:35:08.739 --> 00:35:12.719
spectra of distant quasars provided strong evidence that this diffuse
521
00:35:12.780 --> 00:35:15.639
plasma exists along the lines of sight between Earth and
522
00:35:15.719 --> 00:35:21.260
faraway light sources. In 2020, measurements of dispersion from fast
523
00:35:21.340 --> 00:35:25.559
radio bursts, brief pulses of radio energy from distant galaxies,
524
00:35:26.219 --> 00:35:29.610
further confirmed that the missing ordinary matter resides in the
525
00:35:29.639 --> 00:35:34.639
intergalactic medium, spread across the cosmic web in quantities consistent
526
00:35:34.699 --> 00:35:39.269
with theoretical predictions. Roughly 40-50% of all the normal matter
527
00:35:39.289 --> 00:35:44.130
in the universe, every proton, every neutron, every electron that
528
00:35:44.190 --> 00:35:47.869
is not already inside a galaxy, appears to be suspended
529
00:35:47.929 --> 00:35:52.239
in this hot, impossibly thin haze stretching between the structures
530
00:35:52.280 --> 00:35:54.739
of the cosmos. And here is the part that makes
531
00:35:54.780 --> 00:35:58.840
this discovery so devastating for any hope that intergalactic space
532
00:35:58.900 --> 00:36:01.940
might be less empty than it appears. Even with all
533
00:36:01.980 --> 00:36:05.760
that missing matter accounted for, even with half the universe's
534
00:36:05.900 --> 00:36:10.590
ordinary atoms distributed through the intergalactic medium, the density remains
535
00:36:10.690 --> 00:36:15.210
staggeringly low. The warm, hot intergalactic medium is expected to
536
00:36:15.269 --> 00:36:18.710
contain between 1 and 10 particles per cubic metre in
537
00:36:18.769 --> 00:36:23.639
its densest filamentary regions. In the deep voids between those filaments,
538
00:36:24.119 --> 00:36:27.480
the density drops even lower. you could fill a volume
539
00:36:27.519 --> 00:36:30.539
of intergalactic space equal to the entire Earth and the
540
00:36:30.619 --> 00:36:34.039
total mass of ordinary matter inside that sphere would weigh
541
00:36:34.119 --> 00:36:37.380
less than a large commercial aircraft. The missing baryons are
542
00:36:37.420 --> 00:36:40.840
not missing because they are hiding somewhere dense. They are
543
00:36:40.900 --> 00:36:44.980
missing because they are spread so unimaginably thin that detecting
544
00:36:45.019 --> 00:36:48.739
them at all required decades of technological advancement and some
545
00:36:48.760 --> 00:36:52.269
of the most sensitive instruments ever built. To appreciate the
546
00:36:52.329 --> 00:36:56.360
scale of this thinness, consider a comparison. The air in
547
00:36:56.380 --> 00:36:58.920
the room where you are sitting right now contains roughly
548
00:36:58.920 --> 00:37:04.059
25 trillion trillion molecules in every cubic meter. A cubic
549
00:37:04.139 --> 00:37:07.530
meter of interstellar space inside the Milky Way contains about
550
00:37:07.570 --> 00:37:11.610
a million particles. A cubic meter in the densest part
551
00:37:11.650 --> 00:37:15.909
of the warm hot intergalactic medium, inside a cosmic filament,
552
00:37:16.449 --> 00:37:21.360
contains perhaps 10 particles. And in the deep voids between filaments,
553
00:37:22.119 --> 00:37:26.090
Even that sparse population fades toward fractions of a single
554
00:37:26.150 --> 00:37:30.250
particle per cubic meter. The progression from breathable air to
555
00:37:30.329 --> 00:37:35.510
intergalactic void represents a decrease in density spanning roughly 25
556
00:37:35.510 --> 00:37:39.849
orders of magnitude. That is a factor of 10 trillion trillion.
557
00:37:40.679 --> 00:37:44.900
No analogy can faithfully capture a ratio that large. It
558
00:37:44.940 --> 00:37:47.019
is like comparing the mass of the sun to the
559
00:37:47.059 --> 00:37:50.579
mass of a single bacterium, and then saying the bacterium
560
00:37:50.619 --> 00:37:54.630
is too heavy. The warm, hot intergalactic medium does not
561
00:37:54.670 --> 00:37:58.150
make the void between galaxies feel any less empty. It
562
00:37:58.190 --> 00:38:01.489
makes it feel more tragic. The universe took half its
563
00:38:01.570 --> 00:38:05.360
ordinary matter and smeared it across volumes so vast that
564
00:38:05.380 --> 00:38:09.639
the matter became functionally invisible. It heated this material to
565
00:38:09.760 --> 00:38:13.219
millions of degrees and then dispersed it so thinly that
566
00:38:13.260 --> 00:38:18.829
it cannot form anything. No stars, no planets, no chemistry,
567
00:38:19.550 --> 00:38:24.880
no structure. just an ethereal plasma haunting the darkness between galaxies,
568
00:38:25.400 --> 00:38:27.280
like a ghost of the matter that might have been
569
00:38:27.360 --> 00:38:29.940
something if it had not been scattered across an emptiness
570
00:38:29.980 --> 00:38:33.039
too large to allow it to collapse. But the warm,
571
00:38:33.099 --> 00:38:37.159
hot intergalactic medium is only the luminous fraction, the ordinary
572
00:38:37.239 --> 00:38:41.199
matter component. The majority of mass between galaxies is not
573
00:38:41.320 --> 00:38:46.539
ordinary matter at all. It is dark matter. Invisible, undetectable
574
00:38:46.619 --> 00:38:51.849
by any electromagnetic instrument, interacting with ordinary matter only through gravity.
575
00:38:52.329 --> 00:38:55.789
It constitutes roughly 85% of all matter in the universe,
576
00:38:56.329 --> 00:39:00.510
outweighing ordinary atoms by a ratio of roughly 5 to 1.
577
00:39:00.510 --> 00:39:04.630
Yet despite its dominance, it remains completely invisible to every
578
00:39:04.690 --> 00:39:09.070
telescope ever built. Dark matter forms the scaffolding upon which
579
00:39:09.110 --> 00:39:13.150
the entire visible universe is built, and its distribution reveals
580
00:39:13.190 --> 00:39:17.530
something profound about the architecture of cosmic emptiness. Dark matter
581
00:39:17.590 --> 00:39:22.119
does not scatter randomly through space. It organized itself very
582
00:39:22.219 --> 00:39:26.630
early in the universe's history into a vast three-dimensional network
583
00:39:26.690 --> 00:39:30.519
that cosmologists call the cosmic web. This structure is not
584
00:39:30.559 --> 00:39:34.719
a metaphor. It is a physical reality confirmed through decades
585
00:39:34.760 --> 00:39:40.719
of observation, simulation and gravitational lensing measurements. The cosmic web
586
00:39:40.780 --> 00:39:45.139
consists of four distinct components, each playing a specific role
587
00:39:45.159 --> 00:39:48.599
in the architecture of the universe. Dense nodes sit at
588
00:39:48.619 --> 00:39:53.139
the intersections where multiple streams of matter converge. These nodes
589
00:39:53.179 --> 00:39:57.659
are where galaxy clusters form, the largest gravitationally bound structures
590
00:39:57.699 --> 00:40:02.530
in existence, containing thousands of galaxies and masses, equivalent to
591
00:40:02.590 --> 00:40:07.610
quadrillions of suns. Connecting the nodes are filaments, long, thin
592
00:40:07.750 --> 00:40:10.849
threads of dark matter and gas that stretch across tens
593
00:40:10.929 --> 00:40:14.219
or hundreds of millions of light years. These filaments serve
594
00:40:14.260 --> 00:40:18.360
as the highways of cosmic structure, channeling matter from low-density
595
00:40:18.429 --> 00:40:22.750
regions toward the dense nodes where galaxy clusters grow. Where
596
00:40:22.829 --> 00:40:28.289
filaments intersect at broad angles, they form walls, sheet-like concentrations
597
00:40:28.349 --> 00:40:31.989
of galaxies and dark matter that can extend across hundreds
598
00:40:32.030 --> 00:40:35.789
of millions of light-years while remaining remarkably thin in the
599
00:40:35.829 --> 00:40:40.369
perpendicular direction. And then there are the voids. Cosmic voids
600
00:40:40.409 --> 00:40:43.190
are the dominant feature of the universe. They are not
601
00:40:43.289 --> 00:40:48.179
small gaps between clusters. They are enormous, roughly spherical regions
602
00:40:48.219 --> 00:40:51.019
of space where the density of matter drops far below
603
00:40:51.079 --> 00:40:55.820
the cosmic average. Typical voids measure between 30 and 300
604
00:40:55.820 --> 00:41:01.969
million light-years across. The largest confirmed supervoids exceed 300 million
605
00:41:02.010 --> 00:41:07.110
light-years in diameter, and collectively they account for approximately 80%
606
00:41:07.110 --> 00:41:12.329
of the total volume of the observable universe. 80%. That
607
00:41:12.409 --> 00:41:15.349
number deserves to be repeated because it redefines what the
608
00:41:15.449 --> 00:41:18.809
universe fundamentally is. When you look at a photograph of
609
00:41:18.849 --> 00:41:22.510
the cosmos and see galaxies scattered across the frame, you
610
00:41:22.550 --> 00:41:27.820
are seeing the 20%. The bright parts, the exceptions. The
611
00:41:27.880 --> 00:41:31.300
thin walls and narrow filaments where matter managed to concentrate.
612
00:41:31.900 --> 00:41:35.639
The other 80%, the overwhelming majority of the universe by volume,
613
00:41:36.019 --> 00:41:41.860
is void. Empty. Dark. Structureless. The universe is not a
614
00:41:41.920 --> 00:41:45.179
room full of galaxies. It is an ocean of emptiness
615
00:41:45.219 --> 00:41:48.679
with galaxies clinging to its surface like foam on the waves.
616
00:41:49.460 --> 00:41:52.440
The Botez Void is one of the starkest examples of
617
00:41:52.480 --> 00:41:57.800
this cosmic architecture, discovered in 1981 by astronomer Robert Kirschner
618
00:41:58.139 --> 00:42:02.550
and his team during a survey of galactic redshifts. The
619
00:42:02.590 --> 00:42:06.750
Botez Void is a roughly spherical region of space, approximately
620
00:42:06.750 --> 00:42:12.239
330 million light-years in diameter. It sits about 700 million
621
00:42:12.280 --> 00:42:15.659
light-years from Earth in the direction of the constellation Boötes.
622
00:42:16.519 --> 00:42:23.300
Inside this enormous volume, astronomers have found approximately 60 galaxies. 60.
623
00:42:23.300 --> 00:42:26.059
In a region where the cosmic average would predict roughly 2,000.
624
00:42:26.059 --> 00:42:30.829
The Boötes void is so empty that if the Milky
625
00:42:30.869 --> 00:42:34.389
Way sat at its centre, humans would not have discovered
626
00:42:34.429 --> 00:42:39.610
the existence of other galaxies until the 1960s. When telescope
627
00:42:39.650 --> 00:42:43.010
technology finally became powerful enough to detect objects at the
628
00:42:43.070 --> 00:42:47.130
distances required to see beyond the Void's boundaries, for most
629
00:42:47.170 --> 00:42:50.090
of human history, looking out from the centre of the
630
00:42:50.150 --> 00:42:53.510
Boötes Void, the sky would have appeared to contain nothing
631
00:42:53.570 --> 00:42:57.329
but our own stars. The universe beyond would have been invisible.
632
00:42:57.789 --> 00:43:00.980
The very concept of other galaxies would have seemed absurd.
633
00:43:01.719 --> 00:43:04.699
The few galaxies that do exist inside the Boötes Void
634
00:43:04.760 --> 00:43:08.780
are clustered in a thin, tube-shaped region running through its centre.
635
00:43:09.389 --> 00:43:11.690
as though they were clinging to one final thread of
636
00:43:11.769 --> 00:43:16.949
structure within the emptiness. These void galaxies tend to be small, isolated,
637
00:43:17.489 --> 00:43:22.050
and slowly evolving. Without nearby neighbours to interact with, without
638
00:43:22.090 --> 00:43:26.230
the gravitational collisions and mergers that drive evolution in denser environments,
639
00:43:26.739 --> 00:43:29.739
they drift through the void in a state of cosmic stasis.
640
00:43:30.260 --> 00:43:33.420
They are among the loneliest objects in the known universe.
641
00:43:33.940 --> 00:43:36.320
Think about what that means for the history of science.
642
00:43:37.000 --> 00:43:40.159
The entire revolution in human understanding that began with Edwin
643
00:43:40.179 --> 00:43:44.269
Hubble's discovery that the universe contains other galaxies, a discovery
644
00:43:44.309 --> 00:43:47.389
that shattered humanity's belief that the Milky Way was the
645
00:43:47.449 --> 00:43:52.789
entirety of existence, would never have occurred. A civilization inside
646
00:43:52.809 --> 00:43:56.070
the Boötes Void would have looked outward and seen nothing
647
00:43:56.130 --> 00:43:59.869
beyond its own galaxy. Its cosmology would have stalled at
648
00:43:59.909 --> 00:44:03.199
the threshold of the greatest truth in astronomy, because the
649
00:44:03.300 --> 00:44:06.079
universe around it was too empty to reveal that truth.
650
00:44:06.789 --> 00:44:10.360
the void would not just isolate a galaxy physically. It
651
00:44:10.380 --> 00:44:14.460
would isolate it intellectually, hiding the very existence of the
652
00:44:14.519 --> 00:44:17.719
larger cosmos behind a wall of emptiness too deep for
653
00:44:17.780 --> 00:44:22.780
telescopes to penetrate. The Botez void is not unique. It
654
00:44:22.840 --> 00:44:26.539
is simply one of the largest known examples. The universe
655
00:44:26.599 --> 00:44:31.199
is riddled with voids of varying sizes. The KBC void,
656
00:44:31.699 --> 00:44:34.570
the structure in which our own Milky Way appears to reside,
657
00:44:35.369 --> 00:44:40.119
stretches approximately 2 billion light years across, with a density
658
00:44:40.239 --> 00:44:44.320
roughly 20% lower than the cosmic average. The local void,
659
00:44:44.780 --> 00:44:48.659
an emptier region adjacent to our own galactic neighbourhood, extends
660
00:44:48.739 --> 00:44:52.420
roughly 200 million light years and has been shown to
661
00:44:52.500 --> 00:44:55.980
influence the motion of our galaxy, pushing us away from
662
00:44:56.019 --> 00:44:58.760
its centre at hundreds of thousands of miles per hour.
663
00:44:59.369 --> 00:45:03.289
Wherever astronomers point their instruments and map the three-dimensional distribution
664
00:45:03.309 --> 00:45:07.969
of galaxies, they find the same pattern. Matter concentrates into
665
00:45:08.030 --> 00:45:11.670
thin filaments and walls, and between those structures lie enormous
666
00:45:11.789 --> 00:45:15.590
bubbles of almost nothing. The way these voids formed tells
667
00:45:15.659 --> 00:45:19.539
a story about the universe's fundamental character. In the first
668
00:45:19.599 --> 00:45:22.760
few hundred thousand years after the Big Bang, matter was
669
00:45:22.800 --> 00:45:27.960
distributed almost uniformly across all of space. Almost, but not perfectly.
670
00:45:28.639 --> 00:45:32.079
Tiny quantum fluctuations in the density of the infant universe.
671
00:45:32.670 --> 00:45:37.090
variations of roughly one part in 100,000, created regions that
672
00:45:37.130 --> 00:45:40.949
were ever so slightly denser, or slightly less dense than average.
673
00:45:41.690 --> 00:45:45.659
Gravity took over from there. Regions with slightly more matter
674
00:45:45.739 --> 00:45:50.260
pulled in additional material from their surroundings, growing denser over time.
675
00:45:50.800 --> 00:45:54.739
Regions with slightly less matter lost material to their denser neighbours,
676
00:45:55.179 --> 00:46:00.420
becoming emptier. Over billions of years, this process of gravitational
677
00:46:00.500 --> 00:46:06.519
instability amplified those minuscule initial differences into the dramatic cosmic
678
00:46:06.599 --> 00:46:10.980
web we observe today. Dense regions collapsed into the filaments
679
00:46:11.019 --> 00:46:16.130
and nodes where galaxies formed. Underdense regions expanded into the voids.
680
00:46:16.670 --> 00:46:21.070
The cosmic web is gravity's autobiography, written in the distribution
681
00:46:21.090 --> 00:46:24.050
of matter across the largest scales the universe can offer.
682
00:46:24.829 --> 00:46:28.920
The quantum fluctuations that seeded the voids were unimaginably small.
683
00:46:29.550 --> 00:46:32.949
The variation of one part in 100,000 is so slight
684
00:46:33.449 --> 00:46:36.050
that if you represented the average density of the early
685
00:46:36.150 --> 00:46:40.530
universe as a perfectly flat lake, the fluctuations would correspond
686
00:46:40.570 --> 00:46:43.980
to ripples less than a millimetre high on a surface
687
00:46:44.039 --> 00:46:46.219
stretching from one end of the Earth to the other.
688
00:46:47.000 --> 00:46:52.340
Yet those infinitesimal ripples, amplified by gravity over 13.8 billion
689
00:46:52.380 --> 00:46:56.099
years of cosmic evolution, became the voids and filaments and
690
00:46:56.179 --> 00:46:59.380
clusters that define the structure of everything we can observe.
691
00:47:00.219 --> 00:47:03.579
The largest empty spaces in the universe trace their origin
692
00:47:03.639 --> 00:47:06.760
to the smallest possible variations in the density of the
693
00:47:06.800 --> 00:47:11.599
newborn cosmos. But what makes this architecture so isolating is
694
00:47:11.639 --> 00:47:15.960
the relationship between the structures and the voids. Galaxies do
695
00:47:16.000 --> 00:47:18.610
not sit in the middle of comfortable volumes of space
696
00:47:18.679 --> 00:47:22.969
surrounded by other galaxies at manageable distances. They perch on
697
00:47:22.989 --> 00:47:27.409
the edges of enormous empty bubbles. The filaments where galaxies
698
00:47:27.469 --> 00:47:32.030
concentrate are thin, Cosmological surveys show that typical filaments measure
699
00:47:32.110 --> 00:47:35.730
only about 20 million light years in width, while stretching
700
00:47:35.809 --> 00:47:39.389
across hundreds of millions of light years in length. They
701
00:47:39.409 --> 00:47:44.320
are cosmic threads, disproportionately long and impossibly narrow compared to
702
00:47:44.360 --> 00:47:47.980
the voids they border. A galaxy sitting on one side
703
00:47:48.019 --> 00:47:50.980
of a void and looking across to the nearest filament
704
00:47:51.039 --> 00:47:54.239
on the other side might face a journey of 100
705
00:47:54.239 --> 00:47:57.760
million light years or more through a region containing almost
706
00:47:57.840 --> 00:48:00.570
no matter at all And the voids are not passive,
707
00:48:01.110 --> 00:48:05.690
they are growing. Cosmic expansion stretches all of space, but
708
00:48:05.710 --> 00:48:08.300
the effect is most dramatic in regions where there is
709
00:48:08.360 --> 00:48:12.920
little gravity to resist it. In dense filaments and galaxy clusters,
710
00:48:13.500 --> 00:48:18.519
gravitational attraction slows or halts the expansion locally. Galaxies and
711
00:48:18.559 --> 00:48:23.340
clusters remain gravitationally bound to one another. But inside voids,
712
00:48:23.780 --> 00:48:27.329
where matter is sparse and gravity is weak, Dark energy
713
00:48:27.389 --> 00:48:32.969
drives accelerating expansion essentially unopposed. Voids are expanding faster than
714
00:48:33.010 --> 00:48:37.500
the cosmic average. They are growing larger, becoming emptier, and
715
00:48:37.539 --> 00:48:41.739
pushing galaxies on their borders farther apart. The cosmic web
716
00:48:41.800 --> 00:48:45.719
is not a static structure. It is a dynamic architecture
717
00:48:45.860 --> 00:48:49.019
in which the voids are winning. The empty spaces are
718
00:48:49.059 --> 00:48:52.360
consuming an ever greater share of the cosmic volume, and
719
00:48:52.380 --> 00:48:56.059
the filaments between them are slowly thinning. This means the
720
00:48:56.179 --> 00:49:00.400
isolation between galaxies is not a fixed condition. It is worsening.
721
00:49:01.039 --> 00:49:04.260
The voids that separate galaxies today will be larger tomorrow,
722
00:49:04.840 --> 00:49:08.130
and larger still a billion years from now. The filaments
723
00:49:08.190 --> 00:49:11.869
that connect clusters will stretch thinner. The walls that border
724
00:49:11.909 --> 00:49:15.670
the voids will become more diffuse. Dark energy is reshaping
725
00:49:15.710 --> 00:49:19.630
the cosmic web in real time, slowly dissolving the connections
726
00:49:19.710 --> 00:49:23.610
between structures and enlarging the empty spaces that divide them.
727
00:49:24.519 --> 00:49:28.320
The universe is not merely empty. It is becoming emptier.
728
00:49:29.099 --> 00:49:32.860
The architecture of isolation is deepening with every passing era
729
00:49:32.900 --> 00:49:36.960
of cosmic time. This is the environment that intergalactic distance
730
00:49:37.019 --> 00:49:40.570
must be understood within. The gap between galaxies is not
731
00:49:40.610 --> 00:49:44.489
a featureless blank space of uniform emptiness. It is a
732
00:49:44.610 --> 00:49:49.070
structured emptiness, organized by the cosmic web into regions of
733
00:49:49.210 --> 00:49:53.630
varying desolation. Some directions from any given galaxy lead along
734
00:49:53.670 --> 00:49:56.690
a filament, where the next galaxy might be found within
735
00:49:56.730 --> 00:50:01.489
a few million light years, close by intergalactic standards. Other
736
00:50:01.530 --> 00:50:05.110
directions lead straight into a void, where the nearest galaxy
737
00:50:05.150 --> 00:50:07.989
in that direction might be tens or hundreds of millions
738
00:50:08.030 --> 00:50:12.489
of light years away. The universe is anisotropic in its isolation.
739
00:50:13.269 --> 00:50:16.130
Depending on which way you look from any given galaxy,
740
00:50:16.610 --> 00:50:20.510
the depth of the emptiness changes dramatically. Consider what this
741
00:50:20.550 --> 00:50:23.329
means for a galaxy sitting on the edge of a supervoid.
742
00:50:24.110 --> 00:50:27.150
That galaxy looks outward in one direction and sees the
743
00:50:27.210 --> 00:50:30.130
filament it belongs to, a thin ribbon of light and
744
00:50:30.190 --> 00:50:33.800
matter stretching toward the nearest cluster. In the other direction,
745
00:50:34.099 --> 00:50:38.219
it sees nothing. A gulf of emptiness extending for hundreds
746
00:50:38.260 --> 00:50:43.150
of millions of light years. No stars, no galaxies, no
747
00:50:43.230 --> 00:50:47.090
structure of any kind. Just an expanding void that grows
748
00:50:47.190 --> 00:50:51.050
larger with every passing moment. The galaxy is not surrounded
749
00:50:51.090 --> 00:50:54.269
by other galaxies. It is half surrounded by a thin
750
00:50:54.329 --> 00:50:58.289
band of structure and half surrounded by an abyss. Even
751
00:50:58.349 --> 00:51:02.380
within the filaments themselves, The spacing between galaxies is not
752
00:51:02.460 --> 00:51:06.679
what most people imagine. Galaxies in a typical filament are
753
00:51:06.760 --> 00:51:10.559
separated by distances measured in millions of light years. They
754
00:51:10.599 --> 00:51:13.860
do not cluster tightly like beads on a string. They
755
00:51:13.900 --> 00:51:16.980
are spread along the filament with enormous gaps between them.
756
00:51:17.699 --> 00:51:20.659
Gaps that are small compared to the voids on either side,
757
00:51:20.719 --> 00:51:25.050
but still impossibly large by any human measure. A galaxy
758
00:51:25.110 --> 00:51:28.719
travelling along a filament toward the nearest cluster would pass
759
00:51:28.780 --> 00:51:31.610
through millions of light years of thinning gas and dark
760
00:51:31.659 --> 00:51:35.949
matter before reaching the next significant concentration of stars. The
761
00:51:36.010 --> 00:51:39.469
filament provides a direction but not a road. It is
762
00:51:39.510 --> 00:51:44.010
a vague gravitational guideline stretching across distances that would take
763
00:51:44.090 --> 00:51:47.750
light millions of years to traverse. The cosmic web also
764
00:51:47.829 --> 00:51:51.880
reveals why intergalactic space feels qualitatively harsher than the space
765
00:51:51.929 --> 00:51:56.460
between stars. Within a galaxy, stars are separated by light
766
00:51:56.500 --> 00:52:00.070
years but they are embedded in a shared gravitational structure.
767
00:52:00.690 --> 00:52:03.690
They orbit a common centre. They are bathed in the
768
00:52:03.789 --> 00:52:09.550
same radiation field, the same magnetic environment, the same interstellar medium.
769
00:52:10.309 --> 00:52:13.869
The space between stars is empty compared to planetary surfaces,
770
00:52:14.449 --> 00:52:17.369
but it is rich compared to what lies between galaxies.
771
00:52:18.230 --> 00:52:23.570
The interstellar medium contains gas, dust, cosmic rays, magnetic fields,
772
00:52:24.050 --> 00:52:27.829
and the faint glow of starlight from billions of surrounding suns.
773
00:52:28.489 --> 00:52:32.050
It is a medium in the truest sense, a substance
774
00:52:32.090 --> 00:52:36.469
through which energy and matter can propagate, interact and evolve.
775
00:52:36.989 --> 00:52:41.070
The intergalactic medium has none of this richness. There is
776
00:52:41.110 --> 00:52:45.349
no starlight in the deep void between galaxies, no magnetic
777
00:52:45.409 --> 00:52:49.050
field strong enough to shape particle motion over meaningful distances,
778
00:52:49.949 --> 00:52:53.619
no dust to scatter or absorb radiation, no cosmic rays
779
00:52:53.659 --> 00:52:57.679
at significant densities. The faint, warm, hot plasma that threads
780
00:52:57.739 --> 00:53:01.119
through the filaments is too diffuse to constitute an environment
781
00:53:01.179 --> 00:53:05.469
in any meaningful sense. It cannot carry sound. It cannot
782
00:53:05.530 --> 00:53:10.269
transmit pressure waves. It cannot sustain chemistry. It is matter
783
00:53:10.309 --> 00:53:14.150
in name only, a population of particles so sparse that
784
00:53:14.210 --> 00:53:17.659
each atom exists in effective isolation from every other atom.
785
00:53:18.309 --> 00:53:21.469
separated by distances that might as well be infinite on
786
00:53:21.630 --> 00:53:25.150
any atomic scale. This is why the jump from interstellar
787
00:53:25.190 --> 00:53:30.329
to intergalactic is not a quantitative increase, but a qualitative transformation.
788
00:53:31.230 --> 00:53:35.929
Inside a galaxy, you're in a place. Between galaxies, you're
789
00:53:35.969 --> 00:53:40.340
in an absence. The material conditions change so drastically that
790
00:53:40.380 --> 00:53:43.800
the physics governing your environment shifts from the familiar to
791
00:53:43.840 --> 00:53:49.989
the extreme. Inside a galaxy, Gravity dominates locally, pulling matter together,
792
00:53:50.469 --> 00:53:55.769
forming stars, building structure. In the deep intergalactic void, dark
793
00:53:55.849 --> 00:54:01.030
energy dominates. Gravity is too weak to organise anything. Expansion
794
00:54:01.090 --> 00:54:04.849
is all that happens. Matter does not clump. Structure does
795
00:54:04.889 --> 00:54:09.210
not form. The void simply grows, stretching the already thin
796
00:54:09.269 --> 00:54:13.800
material ever thinner, pushing the already distant walls ever farther away.
797
00:54:14.630 --> 00:54:18.449
And this transformation happens not at some exotic boundary far
798
00:54:18.510 --> 00:54:23.300
from galactic shores. It begins almost immediately. Step outside the
799
00:54:23.340 --> 00:54:27.340
gravitational influence of the Milky Way. Cross beyond the virial
800
00:54:27.400 --> 00:54:30.219
radius where matter is no longer bound to our galaxy.
801
00:54:30.960 --> 00:54:34.320
And within a relatively short distance by cosmic standards, you
802
00:54:34.380 --> 00:54:38.900
enter a regime where the rules change. The interstellar medium thins.
803
00:54:39.480 --> 00:54:43.369
The stellar density drops to zero. The gravitational influence of
804
00:54:43.389 --> 00:54:47.670
the galaxy fades. and you find yourself in the intergalactic medium,
805
00:54:48.309 --> 00:54:51.519
an environment governed not by the familiar forces that build
806
00:54:51.599 --> 00:54:55.780
worlds and stars, but by the slow, implacable expansion of
807
00:54:55.860 --> 00:55:01.019
space itself. The cosmic web makes one more thing devastatingly clear.
808
00:55:01.719 --> 00:55:05.219
The universe's emptiness is not an accident. It is not
809
00:55:05.260 --> 00:55:08.480
a temporary condition that will resolve as galaxies spread out
810
00:55:08.539 --> 00:55:12.199
and fill the gaps. The voids exist because the physics
811
00:55:12.239 --> 00:55:16.670
of the universe requires them. Gravity creates structure by pulling
812
00:55:16.750 --> 00:55:21.400
matter out of underdense regions and concentrating it into overdense ones.
813
00:55:22.219 --> 00:55:26.059
The very process that builds galaxies and clusters also evacuates
814
00:55:26.099 --> 00:55:29.300
the space between them. You cannot have one without the other.
815
00:55:30.179 --> 00:55:34.010
Every filament exists because a void was emptied to create it.
816
00:55:34.949 --> 00:55:38.789
Every galaxy shines because the matter that forms its stars
817
00:55:38.849 --> 00:55:41.909
was pulled from a region that was left darker and
818
00:55:41.949 --> 00:55:45.969
more barren as a result. The structure and the emptiness
819
00:55:46.610 --> 00:55:51.489
are two expressions of the same gravitational process. They are inseparable,
820
00:55:51.969 --> 00:55:55.409
and the emptiness always wins on volume. 80% of the
821
00:55:55.489 --> 00:55:59.639
universe is void. The other 20% is structure, and most
822
00:55:59.679 --> 00:56:03.099
of that structure is thin filaments barely holding their territory
823
00:56:03.159 --> 00:56:07.179
against the expanding darkness on either side. Galaxies are not
824
00:56:07.280 --> 00:56:10.599
sprinkled across the universe like sugar on a table. They
825
00:56:10.639 --> 00:56:13.460
are stranded on the narrow ridges of a vast foam.
826
00:56:14.230 --> 00:56:17.489
separated by bubbles of emptiness so large that the ridges
827
00:56:17.550 --> 00:56:22.000
themselves seem fragile and impermanent by comparison. The Milky Way
828
00:56:22.079 --> 00:56:25.420
sits on one such ridge, part of a filament connected
829
00:56:25.460 --> 00:56:28.599
to a wall connected to a supercluster, and on either
830
00:56:28.679 --> 00:56:32.260
side of that thin line of structure yawn voids that
831
00:56:32.340 --> 00:56:35.809
dwarf everything we have ever seen or mapped or named.
832
00:56:36.590 --> 00:56:39.829
This is the architecture of the universe, not a crowded
833
00:56:39.909 --> 00:56:44.579
ballroom of galaxies dancing at conversational distances, a foam of
834
00:56:44.659 --> 00:56:49.019
darkness punctuated by thin films of matter, where galaxies cling
835
00:56:49.079 --> 00:56:51.889
to the surfaces of enormous empty bubbles and look out
836
00:56:51.949 --> 00:56:56.210
across gulfs so wide that even light, travelling since before
837
00:56:56.289 --> 00:57:00.769
our species existed, has not yet crossed them. The emptiness
838
00:57:00.809 --> 00:57:03.329
is not a bug in the cosmic design, it is
839
00:57:03.389 --> 00:57:07.130
the design. The voids are not holes in the structure,
840
00:57:07.750 --> 00:57:11.170
they are the structure, and the galaxies are for all
841
00:57:11.210 --> 00:57:14.150
their billions of stars and all their trillions of planets,
842
00:57:14.829 --> 00:57:18.389
are just a thin, luminous residue clinging to the edges
843
00:57:18.429 --> 00:57:22.059
of an architecture built primarily from nothing. What this means
844
00:57:22.099 --> 00:57:24.940
for any hope of crossing from one galaxy to another,
845
00:57:25.599 --> 00:57:29.840
what it implies for communication, for travel, for any form
846
00:57:29.880 --> 00:57:33.219
of cosmic connection between the islands of light, is a
847
00:57:33.300 --> 00:57:36.679
question with answers that grow darker at every scale. And
848
00:57:36.719 --> 00:57:39.360
those answers begin to emerge when you stop asking how
849
00:57:39.469 --> 00:57:42.360
far it is and start asking what it would actually
850
00:57:42.420 --> 00:57:45.179
take to get there. There is a moment in every
851
00:57:45.239 --> 00:57:49.880
confrontation with intergalactic distance where the mind shifts from understanding
852
00:57:49.960 --> 00:57:54.659
to surrender. The numbers have been established. The emptiness has
853
00:57:54.679 --> 00:57:58.989
been described. But what truly breaks human intuition is not
854
00:57:59.030 --> 00:58:02.730
the distance or the void. It is the realisation that
855
00:58:02.869 --> 00:58:07.269
no amount of technology, no feat of engineering, no breakthrough
856
00:58:07.309 --> 00:58:10.750
in physics as we currently understand it, can overcome what
857
00:58:10.809 --> 00:58:15.539
the universe has placed between its galaxies. Intergalactic distance does
858
00:58:15.599 --> 00:58:19.780
not merely make travel difficult. It makes travel, communication and
859
00:58:19.840 --> 00:58:24.159
contact functionally impossible across the overwhelming majority of the cosmos.
860
00:58:24.780 --> 00:58:28.090
And the reason goes deeper than most people suspect. Because
861
00:58:28.130 --> 00:58:31.949
the universe is not simply large, it is actively working
862
00:58:32.030 --> 00:58:35.449
against any attempt to cross the gaps. Start with the
863
00:58:35.489 --> 00:58:40.599
most generous scenario imaginable. Forget the limitations of current technology.
864
00:58:41.400 --> 00:58:46.719
Forget chemical rockets, ion drives, solar sails. Imagine that a
865
00:58:46.820 --> 00:58:51.389
civilisation has solved every engineering challenge and built a spacecraft
866
00:58:51.469 --> 00:58:54.510
capable of travelling at a significant fraction of the speed
867
00:58:54.550 --> 00:58:59.159
of light, say 90%. This is not a realistic prospect
868
00:58:59.199 --> 00:59:02.820
for humanity in the foreseeable future, but grant it anyway
869
00:59:02.860 --> 00:59:06.460
for the sake of argument. A ship moving at 90%
870
00:59:06.460 --> 00:59:09.969
of light speed would be the most extraordinary machine ever conceived.
871
00:59:10.869 --> 00:59:13.289
It would cross the distance from Earth to the Sun
872
00:59:13.510 --> 00:59:16.800
in about nine minutes. It would leave the solar system
873
00:59:16.840 --> 00:59:19.820
in hours. It would reach the nearest star in under
874
00:59:19.920 --> 00:59:23.840
five years. Now point that ship toward the Andromeda Galaxy
875
00:59:24.380 --> 00:59:27.460
and fire the engines. At 90% of the speed of light,
876
00:59:28.760 --> 00:59:32.880
the journey to Andromeda would take approximately 2.8 million years
877
00:59:33.360 --> 00:59:37.139
as measured by an observer watching from Earth. The ship itself,
878
00:59:37.579 --> 00:59:41.659
thanks to relativistic time dilation, would experience a shorter journey.
879
00:59:42.380 --> 00:59:47.699
At 90% of light speed, the dilation factor compresses onboard
880
00:59:47.760 --> 00:59:52.659
time by roughly a factor of 2.3. The crew, if
881
00:59:52.739 --> 00:59:56.039
somehow kept alive, would experience the passage of about 1.2
882
00:59:56.039 --> 01:00:00.920
million years This is not a rounding error. It is
883
01:00:00.960 --> 01:00:04.159
a duration that exceeds the entire span of the genus
884
01:00:04.219 --> 01:00:08.340
Homo on Earth. Every human ancestor who ever lived, from
885
01:00:08.380 --> 01:00:11.159
the first toolmakers to the last person born before the
886
01:00:11.199 --> 01:00:14.659
ship launched, would fit inside a fraction of the onboard
887
01:00:14.719 --> 01:00:18.460
travel time. The journey does not merely exceed a human lifetime.
888
01:00:19.159 --> 01:00:23.159
It exceeds the lifetime of the entire human lineage. What
889
01:00:23.219 --> 01:00:25.760
if the ship travelled faster? At 99% of the speed
890
01:00:25.800 --> 01:00:31.619
of light, time dilation compresses the onboard experience more aggressively,
891
01:00:32.360 --> 01:00:35.820
by a factor of about 7. The crew would experience
892
01:00:35.909 --> 01:00:42.349
roughly 350,000 years, still an eternity, still longer than modern
893
01:00:42.409 --> 01:00:47.929
humans have existed. At 99.9% of light speed, the dilation
894
01:00:47.989 --> 01:00:52.920
factor rises to about 22, reducing onboard time to approximately 113,000 years. Better,
895
01:00:52.960 --> 01:01:02.429
but still a span of during which entire civilizations could rise, flourish, collapse,
896
01:01:02.849 --> 01:01:08.030
and be forgotten dozens of times over. Even at 99.99%
897
01:01:08.179 --> 01:01:11.920
of light speed, a velocity so extreme that the energy
898
01:01:11.980 --> 01:01:15.579
required to achieve it verges on the total mass energy
899
01:01:15.619 --> 01:01:19.679
of the spacecraft itself. The crew would still experience tens
900
01:01:19.739 --> 01:01:22.719
of thousands of years of travel. No version of this
901
01:01:22.760 --> 01:01:27.860
calculation produces a human-scale journey. The distance is simply too
902
01:01:27.940 --> 01:01:32.019
enormous for even the most extreme relativistic effects to compress
903
01:01:32.059 --> 01:01:35.679
it into anything manageable. And this is the optimistic case.
904
01:01:36.340 --> 01:01:38.820
This assumes a ship travelling at a velocity that would
905
01:01:38.860 --> 01:01:43.329
require energy inputs beyond anything physics currently allows at practical scales.
906
01:01:44.210 --> 01:01:49.230
Accelerating even a modest spacecraft to 90% of light speed
907
01:01:49.789 --> 01:01:54.320
demands energy quantities that dwarf the total output of human civilisation.
908
01:01:55.130 --> 01:01:58.730
The kinetic energy of a single kilogram of matter moving
909
01:01:58.769 --> 01:02:04.449
at that speed is approximately 117 quadrillion joules. For a
910
01:02:04.510 --> 01:02:08.530
spacecraft large enough to carry fuel, shielding and any form
911
01:02:08.570 --> 01:02:12.429
of life support, the energy budget climbs toward values that
912
01:02:12.469 --> 01:02:16.210
can only be expressed in terms of stellar output. You
913
01:02:16.250 --> 01:02:19.269
would need to capture and convert a meaningful fraction of
914
01:02:19.309 --> 01:02:22.849
an entire star's energy into to accelerate a ship to
915
01:02:22.889 --> 01:02:27.130
the speed required for an intergalactic crossing, and then capture
916
01:02:27.170 --> 01:02:29.769
and convert it again to decelerate on the other side.
917
01:02:30.510 --> 01:02:33.429
The engineering is not merely difficult, it sits at the
918
01:02:33.469 --> 01:02:37.320
boundary between ambitious and physically absurd. To put the energy
919
01:02:37.380 --> 01:02:41.480
problem in concrete terms, the total energy consumption of all
920
01:02:41.539 --> 01:02:45.500
human civilization in a single year is approximately 580 exajoules.
921
01:02:45.519 --> 01:02:52.960
Accelerating a modest 10,000 kilogram spacecraft to 90% of light
922
01:02:53.019 --> 01:02:58.260
speed would require roughly 1.2 times 10 to the 21st joules,
923
01:02:59.099 --> 01:03:02.159
an amount equivalent to more than 2,000 years of total
924
01:03:02.219 --> 01:03:06.159
human energy production. For a ship massive enough to sustain
925
01:03:06.199 --> 01:03:10.369
a crew, the figure climbs by orders of magnitude. And
926
01:03:10.389 --> 01:03:15.409
this calculation assumes perfect efficiency. No waste heat, no losses,
927
01:03:16.070 --> 01:03:20.769
every joule of energy converted directly into kinetic motion. Real
928
01:03:20.849 --> 01:03:25.289
propulsion systems are nowhere near that efficient. The gap between
929
01:03:25.329 --> 01:03:28.510
what we can build and what intergalactic travel demands is
930
01:03:28.570 --> 01:03:31.909
not a gap that incremental improvement can close. It is
931
01:03:31.949 --> 01:03:35.489
a chasm that requires fundamentally new physics to even begin
932
01:03:35.550 --> 01:03:39.409
to address. But even if that problem were solved, even
933
01:03:39.449 --> 01:03:42.429
if a civilization harnessed the energy of its star and
934
01:03:42.469 --> 01:03:46.199
built the impossible ship, the journey itself would render the
935
01:03:46.239 --> 01:03:50.809
mission meaningless in almost every practical sense. At 90% of
936
01:03:50.849 --> 01:03:53.989
light speed, the ship would arrive at Andromeda after more
937
01:03:54.010 --> 01:03:58.130
than a million years of onboard time. No biological organism
938
01:03:58.190 --> 01:04:01.969
known to science can survive a duration remotely approaching that span.
939
01:04:02.769 --> 01:04:06.670
No mechanical system built from known materials can remain functional
940
01:04:06.730 --> 01:04:12.139
across geological timescales without maintenance, repair and replacement. The ship
941
01:04:12.179 --> 01:04:14.860
would need to be not a vessel but a self-sustaining
942
01:04:14.900 --> 01:04:19.019
world capable of enduring longer than most species persist on Earth.
943
01:04:19.849 --> 01:04:23.150
It would need to carry not passengers, but a civilisation.
944
01:04:23.909 --> 01:04:28.750
One that could reproduce, evolve and maintain its technological infrastructure
945
01:04:29.230 --> 01:04:33.519
across thousands of generations. The crew that arrived at Andromeda
946
01:04:33.539 --> 01:04:36.639
would bear no meaningful resemblance to the crew that departed.
947
01:04:37.199 --> 01:04:40.420
They would be a different species, shaped by a million
948
01:04:40.440 --> 01:04:44.139
years of isolated evolution in a metal shell crossing the void.
949
01:04:44.920 --> 01:04:48.929
And the civilisation they left behind would be gone. 2.8
950
01:04:48.929 --> 01:04:52.369
million years would pass on Earth between departure and arrival.
951
01:04:53.150 --> 01:04:56.750
Whatever culture launched the ship would have transformed beyond recognition,
952
01:04:57.289 --> 01:05:00.500
or vanished entirely long before the first signal came back.
953
01:05:01.380 --> 01:05:04.360
There would be no one to receive the report, no
954
01:05:04.460 --> 01:05:08.000
one to celebrate the achievement. The ship would arrive at
955
01:05:08.019 --> 01:05:11.920
a galaxy full of a trillion unfamiliar stars, carrying the
956
01:05:11.960 --> 01:05:16.110
descendants of a civilization that no longer existed, reporting to
957
01:05:16.170 --> 01:05:19.280
a home that had forgotten they were coming. The distance
958
01:05:19.320 --> 01:05:24.030
does not just separate locations, it separates eras. It turns
959
01:05:24.309 --> 01:05:27.869
every intergalactic journey into a one-way trip through time as
960
01:05:27.929 --> 01:05:31.070
well as space. This is the scenario for the nearest
961
01:05:31.130 --> 01:05:35.289
large galaxy. Andromeda is the easiest target. It is the
962
01:05:35.349 --> 01:05:40.369
closest major spiral, the best case mission. For galaxies beyond
963
01:05:40.429 --> 01:05:45.489
the local group, the numbers escalate into outright absurdity. The
964
01:05:45.550 --> 01:05:51.329
Virgo Cluster sits 54 million light-years away. At 90% of light-speed,
965
01:05:51.909 --> 01:05:54.670
the journey would take 60 million years as measured from
966
01:05:54.750 --> 01:05:59.199
Earth and roughly 26 million years on board. The Coma Cluster,
967
01:05:59.820 --> 01:06:05.280
a rich concentration of galaxies, lies 320 million light-years distant.
968
01:06:06.119 --> 01:06:11.139
The trip would consume over 350 million years, a duration
969
01:06:11.199 --> 01:06:14.869
stretching back to the early Carboniferous Period on Earth An
970
01:06:15.010 --> 01:06:18.250
era when shallow seas covered much of the continents and
971
01:06:18.269 --> 01:06:21.809
the earliest four-limbed creatures were still adapting to life beyond
972
01:06:21.849 --> 01:06:26.130
the water's edge. No one is crossing that distance. No
973
01:06:26.210 --> 01:06:31.380
technology alters the fundamental temporal cost of crossing 320 million
974
01:06:31.440 --> 01:06:35.400
light-years of expanding void. But the truly devastating blow to
975
01:06:35.460 --> 01:06:38.460
intergalactic travel does not come from distance or energy or
976
01:06:38.500 --> 01:06:44.199
time dilation. It comes from the universe itself. Space is expanding.
977
01:06:44.860 --> 01:06:48.840
Not metaphorically. Not in the sense that galaxies are flying
978
01:06:48.909 --> 01:06:53.409
apart through a static void. The fabric of spacetime is stretching,
979
01:06:53.849 --> 01:06:57.510
increasing the distance between all points that are not gravitationally
980
01:06:57.590 --> 01:07:03.800
bound together. Every second, the space between galaxies grows. Every moment,
981
01:07:04.239 --> 01:07:07.900
the void gets wider. And the farther away a galaxy is,
982
01:07:08.480 --> 01:07:12.559
the faster the space between it and us expands. This
983
01:07:12.639 --> 01:07:16.920
relationship was first described by Edwin Hubble in 1929 and
984
01:07:16.980 --> 01:07:20.280
is now called Hubble's Law. It states that the recession
985
01:07:20.320 --> 01:07:24.260
velocity of a galaxy is proportional to its distance. The
986
01:07:24.300 --> 01:07:31.079
proportionality constant, the Hubble constant, currently measures approximately 67 to
987
01:07:31.079 --> 01:07:35.719
73 km per second per megaparsec, depending on which measurement
988
01:07:35.760 --> 01:07:39.570
technique is used. The exact value remains a subject of
989
01:07:39.710 --> 01:07:43.510
active scientific debate known as the Hubble Tension, but the
990
01:07:43.550 --> 01:07:47.179
implications of the law itself are not in dispute. For
991
01:07:47.320 --> 01:07:52.679
every megaparsec of distance, roughly 3.26 million light years, the
992
01:07:52.719 --> 01:07:56.900
recession velocity of a galaxy increases by approximately 70 km
993
01:07:56.940 --> 01:08:02.440
per second. At first glance, this seems modest, 70 km
994
01:08:02.500 --> 01:08:06.619
per second per megaparsec, but the effect compounds with distance.
995
01:08:07.260 --> 01:08:11.960
A galaxy 10 megaparsecs away recedes at 700 kilometers per second.
996
01:08:12.780 --> 01:08:18.279
A galaxy 100 megaparsecs away recedes at 7,000 kilometers per second.
997
01:08:19.050 --> 01:08:24.670
A galaxy 1,000 megaparsecs away recedes at 70,000 kilometers per second.
998
01:08:25.489 --> 01:08:29.630
And the speed of light is approximately 300,000 kilometers per second.
999
01:08:30.250 --> 01:08:33.390
This means that at a distance of roughly 14 billion
1000
01:08:33.449 --> 01:08:37.819
light years, the recession velocity of a galaxy equals the
1001
01:08:37.890 --> 01:08:42.590
speed of light. Beyond that distance, galaxies recede faster than light.
1002
01:08:43.409 --> 01:08:48.350
This does not violate Einstein's theory of relativity. Relativity prohibits
1003
01:08:48.430 --> 01:08:51.949
objects from moving through space faster than light. It says
1004
01:08:52.090 --> 01:08:55.989
nothing about space itself, stretching at any rate it pleases.
1005
01:08:56.770 --> 01:08:59.949
Galaxies beyond the Hubble radius are not moving through space
1006
01:09:00.109 --> 01:09:04.170
at superluminal velocities. They are sitting relatively still in their
1007
01:09:04.210 --> 01:09:07.520
local patch of space-time, while the space between us and
1008
01:09:07.529 --> 01:09:11.260
them expands faster than light can cross it. The distinction
1009
01:09:11.300 --> 01:09:15.380
is technical, but the consequence is absolute. You might assume
1010
01:09:15.420 --> 01:09:18.800
this means those galaxies are forever beyond our reach. but
1011
01:09:18.819 --> 01:09:23.050
the physics is more subtle and, ultimately, more devastating. Many
1012
01:09:23.090 --> 01:09:26.130
of the galaxies we observe today were receding faster than
1013
01:09:26.189 --> 01:09:29.270
light when they emitted the photons now reaching our telescopes.
1014
01:09:30.050 --> 01:09:33.829
In a decelerating universe, light from beyond the Hubble radius
1015
01:09:33.869 --> 01:09:37.760
could eventually catch up as expansion slowed. But our universe
1016
01:09:37.880 --> 01:09:43.380
is not decelerating. It is accelerating. Dark energy ensures the
1017
01:09:43.439 --> 01:09:47.409
expansion speeds up rather than slowing down. and that acceleration
1018
01:09:47.489 --> 01:09:51.039
creates a grimmer boundary. The cosmic event horizon is the
1019
01:09:51.159 --> 01:09:54.899
true line of no return. The distance beyond which light
1020
01:09:54.939 --> 01:09:57.779
emitted now will never reach us no matter how long
1021
01:09:57.819 --> 01:10:02.319
the universe endures. It currently sits at approximately 16 to
1022
01:10:02.319 --> 01:10:05.739
18 billion light years. That sounds like it encompasses a
1023
01:10:05.899 --> 01:10:10.050
vast volume of space. It does not. The observable universe
1024
01:10:10.130 --> 01:10:16.289
extends 46.5 billion light years in every direction. The reachable universe...
1025
01:10:16.430 --> 01:10:19.619
The portion we could theoretically still touch if we departed
1026
01:10:19.680 --> 01:10:22.760
at light speed right now is a small bubble inside
1027
01:10:22.819 --> 01:10:27.359
that larger sphere. Current estimates suggest that only about 6%
1028
01:10:27.359 --> 01:10:31.819
of the galaxies within the observable universe remain theoretically reachable.
1029
01:10:32.500 --> 01:10:36.819
The other 94% are already gone. They are receding too fast.
1030
01:10:37.720 --> 01:10:41.489
Space between us and them is expanding too rapidly. Even
1031
01:10:41.609 --> 01:10:46.279
light cannot catch them. They are visible but untouchable, observable
1032
01:10:46.359 --> 01:10:51.819
but permanently isolated from any form of contact. 94%. Out
1033
01:10:51.859 --> 01:10:55.680
of the estimated 2 trillion galaxies in the observable universe,
1034
01:10:56.350 --> 01:10:59.909
approximately 1.9 trillion of them are already beyond the reach
1035
01:10:59.949 --> 01:11:03.949
of any signal, any ship, any message we could ever send.
1036
01:11:04.829 --> 01:11:09.590
Even at the speed of light, even starting today, they exist.
1037
01:11:10.590 --> 01:11:14.970
We can see them. Their light is still arriving. Photons
1038
01:11:15.029 --> 01:11:17.930
that began their journey billions of years ago when the
1039
01:11:17.970 --> 01:11:21.449
galaxies were closer and the expansion had not yet carried
1040
01:11:21.470 --> 01:11:25.829
them past the horizon of reachability. But those galaxies, as
1041
01:11:25.869 --> 01:11:29.670
they exist right now, are forever beyond our reach. The
1042
01:11:29.710 --> 01:11:32.510
light we see from them is a fossil, a record
1043
01:11:32.550 --> 01:11:34.489
of where they used to be when the universe was
1044
01:11:34.550 --> 01:11:38.369
younger and smaller. The galaxies themselves have long since crossed
1045
01:11:38.390 --> 01:11:42.510
the boundary into permanent isolation. To make that number visceral,
1046
01:11:43.100 --> 01:11:47.239
Consider that the Milky Way alone contains somewhere between 200
1047
01:11:47.239 --> 01:11:53.149
billion and 400 billion stars. It is one galaxy, the 1.9
1048
01:11:53.149 --> 01:11:57.710
trillion galaxies we can never reach contain, collectively, somewhere in
1049
01:11:57.770 --> 01:12:01.989
the neighbourhood of 100 sextillion stars. Each of those stars
1050
01:12:02.050 --> 01:12:05.899
may host planets. Each of those planets may harbour conditions
1051
01:12:05.979 --> 01:12:10.079
suitable for chemistry, for biology, for the emergence of life
1052
01:12:10.260 --> 01:12:13.300
or intelligence. and every single one of them is forever
1053
01:12:13.399 --> 01:12:17.000
sealed behind a horizon of expanding space that no signal,
1054
01:12:17.100 --> 01:12:22.020
no ship, no thought experiment can penetrate. Whatever exists out there,
1055
01:12:22.579 --> 01:12:26.890
whatever civilizations may have arisen, whatever wonders may have been built,
1056
01:12:27.470 --> 01:12:30.699
they are as inaccessible to us as if they existed
1057
01:12:30.779 --> 01:12:34.890
in a separate universe entirely. In every practical sense, they do,
1058
01:12:35.670 --> 01:12:40.439
and the situation is getting worse. Dark energy, The mysterious
1059
01:12:40.520 --> 01:12:44.939
force driving the acceleration of cosmic expansion ensures that the
1060
01:12:45.000 --> 01:12:49.390
reachable universe shrinks with every passing moment. Galaxies that are
1061
01:12:49.449 --> 01:12:52.729
currently within the cosmic event horizon will eventually cross beyond
1062
01:12:52.810 --> 01:12:55.890
it as the expansion carries them farther away. With every
1063
01:12:55.909 --> 01:12:59.970
year that passes, hundreds of millions of additional stars slip
1064
01:13:00.010 --> 01:13:04.729
beyond the reachability threshold. Entire galaxies are crossing the boundary
1065
01:13:04.770 --> 01:13:07.229
and vanishing from the set of objects we could ever
1066
01:13:07.329 --> 01:13:12.869
theoretically contact. the reachable universe is not stable. It is contracting,
1067
01:13:13.649 --> 01:13:18.590
slowly but relentlessly, as dark energy pushes the cosmos apart
1068
01:13:18.649 --> 01:13:22.130
at an accelerating rate. The endpoint of this process is
1069
01:13:22.270 --> 01:13:27.689
total isolation. Current models project that within 100 to 150
1070
01:13:27.689 --> 01:13:31.289
billion years, every galaxy outside the local group will have
1071
01:13:31.329 --> 01:13:36.670
receded beyond the cosmic event horizon permanently. The Milky Way, Andromeda,
1072
01:13:37.069 --> 01:13:39.960
and the rest of our gravitationally bound family will have
1073
01:13:40.039 --> 01:13:44.159
merged into a single structure surrounded by an expanding darkness
1074
01:13:44.220 --> 01:13:48.220
that no telescope could ever penetrate. What that final loneliness
1075
01:13:48.260 --> 01:13:51.020
will look like, what it will mean for any civilization
1076
01:13:51.039 --> 01:13:54.560
that inherits it, is a question that demands its own reckoning.
1077
01:13:55.279 --> 01:13:59.000
This process has a name among cosmologists. They call it
1078
01:13:59.039 --> 01:14:02.279
the shrinking of the cosmic horizon. It is one of
1079
01:14:02.319 --> 01:14:08.010
the most counterintuitive predictions of modern cosmology. In our everyday experience,
1080
01:14:08.109 --> 01:14:12.029
horizons expand as we climb higher or move faster. From
1081
01:14:12.069 --> 01:14:14.850
the top of a mountain you can see farther. In
1082
01:14:14.890 --> 01:14:18.880
a faster airplane you can reach more destinations. The cosmic
1083
01:14:18.909 --> 01:14:22.520
horizon does the opposite. As time passes, the boundary of
1084
01:14:22.560 --> 01:14:26.399
what we can reach contracts rather than expands. The universe
1085
01:14:26.420 --> 01:14:29.850
gets bigger, but our accessible share of it gets smaller.
1086
01:14:30.279 --> 01:14:34.250
We are not exploring an expanding frontier. We are watching
1087
01:14:34.289 --> 01:14:38.569
a closing door. This future is not speculative. It is
1088
01:14:38.630 --> 01:14:43.170
the direct consequence of observations we have already confirmed. Dark
1089
01:14:43.250 --> 01:14:48.270
energy is real. Cosmic acceleration is measured. The expansion rate
1090
01:14:48.329 --> 01:14:53.060
is known. The math leads to one conclusion. The universe
1091
01:14:53.109 --> 01:14:57.020
is systematically cutting off every connection between its largest structures.
1092
01:14:57.920 --> 01:15:02.920
One by one, galaxy by galaxy, the cosmos is isolating itself,
1093
01:15:03.729 --> 01:15:06.659
dismantling the bridges of light that currently allow us to
1094
01:15:06.699 --> 01:15:09.899
see across billions of light years and replacing them with
1095
01:15:09.939 --> 01:15:14.140
an expanding darkness that no signal can penetrate. Now consider
1096
01:15:14.199 --> 01:15:18.140
what this means for communication, even within the small fraction
1097
01:15:18.180 --> 01:15:21.649
of the universe that remains reachable. Sending a message to
1098
01:15:21.689 --> 01:15:25.550
the nearest large galaxy, Andromeda, would take two and a
1099
01:15:25.609 --> 01:15:29.109
half million years at the speed of light. A response,
1100
01:15:29.510 --> 01:15:32.100
if anyone were listening, would take another two and a
1101
01:15:32.140 --> 01:15:36.479
half million years to return. A single round trip exchange
1102
01:15:36.520 --> 01:15:42.880
would consume five million years. No conversation is possible. No negotiation,
1103
01:15:43.420 --> 01:15:48.760
no cultural exchange, no alliance, no warning. The communication delay
1104
01:15:49.140 --> 01:15:52.760
turns every interaction into a monologue delivered to an audience
1105
01:15:52.800 --> 01:15:55.260
that may not exist by the time the words arrive.
1106
01:15:56.020 --> 01:16:00.520
For galaxies beyond the local group, the situation is qualitatively worse.
1107
01:16:01.329 --> 01:16:04.750
A message sent to the Virgo cluster would take 54
1108
01:16:04.750 --> 01:16:10.060
million years to arrive. By the time a reply could return,
1109
01:16:10.060 --> 01:16:13.500
108 million years would have elapsed. A message to the
1110
01:16:13.579 --> 01:16:16.979
Coma cluster would take over 600 million years for a
1111
01:16:17.039 --> 01:16:22.729
round trip. These are not communication timescales. They are geological timescales.
1112
01:16:23.250 --> 01:16:25.930
They are intervals long enough for entire branches of the
1113
01:16:26.010 --> 01:16:29.180
evolutionary tree to appear and go extinct. They are long
1114
01:16:29.220 --> 01:16:32.659
enough for continents to reshape themselves, for oceans to open
1115
01:16:32.699 --> 01:16:36.500
and close, for the very chemistry of Earth's atmosphere to transform.
1116
01:16:37.180 --> 01:16:40.500
Sending a radio signal to a galaxy 300 million light
1117
01:16:40.520 --> 01:16:43.079
years away is not like mailing a letter to a
1118
01:16:43.140 --> 01:16:46.100
distant country. It is like carving a message on a
1119
01:16:46.180 --> 01:16:49.239
stone and burying it for a future species to find
1120
01:16:49.340 --> 01:16:53.079
after your entire civilization has been forgotten. And even this
1121
01:16:53.159 --> 01:16:57.460
grim picture understates the problem, because the messages themselves face
1122
01:16:57.500 --> 01:17:02.390
an additional enemy. cosmic expansion stretches the wavelength of any
1123
01:17:02.470 --> 01:17:06.489
signal in transit. A radio transmission sent at a specific
1124
01:17:06.550 --> 01:17:10.340
frequency will arrive at its destination with a longer wavelength
1125
01:17:10.399 --> 01:17:13.720
and lower energy than it started with. Over millions or
1126
01:17:13.840 --> 01:17:17.119
billions of light years of travel through expanding space, this
1127
01:17:17.260 --> 01:17:21.539
redshift accumulates. A signal that began as a tight, coherent
1128
01:17:21.600 --> 01:17:24.939
radio beam will arrive as a faint, stretched whisper at
1129
01:17:25.020 --> 01:17:28.300
frequencies that may not even be detectable by the receiving
1130
01:17:28.380 --> 01:17:33.779
civilization's instruments. Assuming any such civilization exists and is listening,
1131
01:17:34.399 --> 01:17:37.329
the expansion of space does not merely delay the message,
1132
01:17:37.930 --> 01:17:42.710
it degrades it. Over sufficient distances, it erases the message entirely,
1133
01:17:43.229 --> 01:17:46.029
stretching the signal to wavelength so long that it becomes
1134
01:17:46.170 --> 01:17:50.029
indistinguishable from the background noise of the cosmos. Consider a
1135
01:17:50.090 --> 01:17:55.260
practical example. If a civilization in the Virgo cluster transmitted
1136
01:17:55.310 --> 01:17:59.279
a powerful radio signal toward us today, at a frequency
1137
01:17:59.319 --> 01:18:03.359
of 1,000 megahertz, the signal would arrive at Earth in
1138
01:18:03.359 --> 01:18:08.300
54 million years. But during that transit, the expansion of
1139
01:18:08.380 --> 01:18:13.289
space would stretch the signal's wavelength. Over 54 million light-years
1140
01:18:13.350 --> 01:18:17.409
of expanding space, the redshift would be small but measurable.
1141
01:18:18.109 --> 01:18:22.199
For more distant galaxies, the effect becomes crippling. A signal
1142
01:18:22.239 --> 01:18:25.279
from a galaxy 1 billion light-years away would arrive with
1143
01:18:25.319 --> 01:18:30.050
its wavelength stretched by roughly 7%. A signal from 5
1144
01:18:30.050 --> 01:18:34.850
billion light-years away would arrive stretched by roughly 40%. A
1145
01:18:34.930 --> 01:18:38.210
signal from 10 billion light-years would arrive with its wavelength
1146
01:18:38.289 --> 01:18:42.619
more than doubled. At some point, the stretching pushes the
1147
01:18:42.680 --> 01:18:46.479
signal below the noise floor of any detector. The universe
1148
01:18:46.500 --> 01:18:51.390
does not merely make long distance calls expensive. them into silence.
1149
01:18:52.229 --> 01:18:55.989
The universe, it turns out, is not just large and empty.
1150
01:18:56.640 --> 01:19:00.960
It is actively hostile to connection. Every mechanism that could
1151
01:19:01.079 --> 01:19:07.430
theoretically link one galaxy to another– travel, signalling, observation– faces
1152
01:19:07.489 --> 01:19:11.529
a barrier that is not technological but structural. The expansion
1153
01:19:11.569 --> 01:19:15.079
of space ensures that the vast majority of galaxies are
1154
01:19:15.199 --> 01:19:19.939
permanently beyond contact. The energy requirements of near light speed
1155
01:19:20.020 --> 01:19:25.010
travel ensure that even nearby galaxies require civilizational sacrifice to reach.
1156
01:19:25.810 --> 01:19:30.210
The time delays ensure that even successful communication spans intervals
1157
01:19:30.289 --> 01:19:34.439
longer than species typically survive. and the redshift ensures that
1158
01:19:34.520 --> 01:19:38.920
signals degrade and eventually vanish into the noise. This transforms
1159
01:19:38.979 --> 01:19:42.399
the meaning of intergalactic distance. It is not a challenge
1160
01:19:42.439 --> 01:19:46.100
to be overcome. It is a feature of the universe's design.
1161
01:19:46.800 --> 01:19:49.840
The cosmos does not want its galaxies to be connected.
1162
01:19:50.659 --> 01:19:55.300
That phrasing is anthropomorphic and imprecise, but it captures something
1163
01:19:55.460 --> 01:19:58.739
real about the physics. The laws of nature as we
1164
01:19:58.800 --> 01:20:03.390
understand them do not permit meaningful interaction between galaxies separated
1165
01:20:03.449 --> 01:20:07.420
by cosmological distances. The speed of light sets an upper
1166
01:20:07.479 --> 01:20:11.199
limit on how fast information can travel. The expansion of
1167
01:20:11.279 --> 01:20:14.770
space ensures that most distances grow faster than that limit.
1168
01:20:15.329 --> 01:20:19.869
Dark energy guarantees that the growth will accelerate. Together, these
1169
01:20:19.930 --> 01:20:23.050
constraints create a universe that is not merely large but
1170
01:20:23.130 --> 01:20:27.899
structurally partitioned. divided into islands of matter surrounded by expanding
1171
01:20:27.960 --> 01:20:31.760
voids that no technology can bridge. The local group is
1172
01:20:31.840 --> 01:20:38.869
our island. The Milky Way, Andromeda, Triangulum, and approximately 130
1173
01:20:38.869 --> 01:20:43.930
smaller galaxies comprise our gravitationally bound family. These galaxies are
1174
01:20:43.949 --> 01:20:47.409
close enough and massive enough that their mutual gravitational attraction
1175
01:20:47.569 --> 01:20:52.020
overcomes the cosmic expansion. They will not fly apart. They
1176
01:20:52.060 --> 01:20:55.529
will not recede beyond the cosmic event horizon. Over the
1177
01:20:55.590 --> 01:21:00.250
next several billion years, they will merge, interact, exchange stars
1178
01:21:00.310 --> 01:21:04.600
and gas, and eventually collapse into a single enormous galaxy.
1179
01:21:05.239 --> 01:21:08.680
This merged structure will be our permanent home, the only
1180
01:21:08.720 --> 01:21:13.020
galactic community we will ever belong to. Everything else is leaving.
1181
01:21:13.659 --> 01:21:19.100
The Virgo Cluster, the nearest major galaxy cluster, is gravitationally
1182
01:21:19.180 --> 01:21:23.489
unbound from the local group. Cosmic expansion is carrying it away.
1183
01:21:24.260 --> 01:21:28.319
The Laniakea supercluster, the immense structure to which the local
1184
01:21:28.359 --> 01:21:32.970
group belongs, is not a gravitationally bound system despite its name.
1185
01:21:33.729 --> 01:21:36.550
It is a flow pattern, a region where galaxies are
1186
01:21:36.609 --> 01:21:40.380
moving toward a common gravitational attractor, but the expansion of
1187
01:21:40.439 --> 01:21:45.079
space will eventually overwhelm even those flows. The galaxies of
1188
01:21:45.140 --> 01:21:50.649
Laniakea will drift apart. The supercluster will dissolve. The nodes
1189
01:21:50.710 --> 01:21:53.289
and filaments of the cosmic web will thin and stretch
1190
01:21:53.350 --> 01:21:56.810
and eventually snap as dark energy tears the connections between them.
1191
01:21:57.210 --> 01:22:01.229
The universe's large-scale structure is temporary. The cosmic web is
1192
01:22:01.289 --> 01:22:05.770
not a permanent architecture. It is a phase, a transient
1193
01:22:05.840 --> 01:22:09.279
arrangement of matter that exists only because the universe is
1194
01:22:09.319 --> 01:22:12.939
still young enough for gravity to compete with expansion. In
1195
01:22:12.960 --> 01:22:19.460
the deep future, expansion wins. The web dissolves. The galaxies disperse.
1196
01:22:20.090 --> 01:22:23.729
and each gravitationally bound island finds itself alone in an
1197
01:22:23.890 --> 01:22:27.729
ocean of darkness that grows wider every second. This is
1198
01:22:27.789 --> 01:22:31.359
not a failure of ambition. It is not a consequence
1199
01:22:31.399 --> 01:22:35.800
of insufficient technology. It is a structural property of reality.
1200
01:22:36.560 --> 01:22:40.199
The universe was not built for intergalactic connection. It was
1201
01:22:40.300 --> 01:22:44.569
built with rules that guarantee intergalactic isolation. The speed of
1202
01:22:44.649 --> 01:22:48.560
light creates a maximum velocity. The expansion of space creates
1203
01:22:48.600 --> 01:22:52.300
a minimum rate at which distances grow. Dark energy creates
1204
01:22:52.359 --> 01:22:57.199
a floor beneath which the expansion cannot fall. These three constraints,
1205
01:22:57.930 --> 01:23:01.590
woven into the deepest physics of the cosmos, produce a
1206
01:23:01.750 --> 01:23:05.609
universe in which galaxies are born into isolation and remain
1207
01:23:05.649 --> 01:23:09.010
there forever. The distance between them is not a problem
1208
01:23:09.050 --> 01:23:11.729
to be solved. It is a sentence to be served.
1209
01:23:12.510 --> 01:23:15.850
What we observe today the filaments and clusters and walls
1210
01:23:15.890 --> 01:23:19.170
that seem to give the universe its shape, will not last.
1211
01:23:19.829 --> 01:23:22.970
The forces holding them together are already losing ground to
1212
01:23:22.989 --> 01:23:26.560
the forces pulling them apart. And what that unravelling will
1213
01:23:26.640 --> 01:23:30.000
ultimately leave behind is something far lonelier than even the
1214
01:23:30.079 --> 01:23:34.819
present emptiness suggests. This is the scale that breaks everything.
1215
01:23:35.539 --> 01:23:39.739
Not merely a large distance, not merely a challenging engineering problem,
1216
01:23:40.510 --> 01:23:43.369
a structural feature of reality that renders most of the
1217
01:23:43.430 --> 01:23:48.319
cosmos permanently inaccessible. The gaps between galaxies are not gaps
1218
01:23:48.359 --> 01:23:50.779
that could be crossed with better engines or more time.
1219
01:23:51.060 --> 01:23:54.199
They are walls built from the expansion of spacetime itself,
1220
01:23:54.800 --> 01:23:58.420
growing higher and thicker with every passing era, sealing each
1221
01:23:58.500 --> 01:24:02.039
galaxy behind a horizon that no signal can penetrate and
1222
01:24:02.100 --> 01:24:06.640
no ship can cross. The universe contains two trillion galaxies.
1223
01:24:07.260 --> 01:24:10.180
We can reach roughly six percent of them, and that
1224
01:24:10.239 --> 01:24:15.050
number is shrinking. Every day, the reachable cosmos contracts by
1225
01:24:15.090 --> 01:24:20.909
a volume containing millions of stars. Every century, entire galaxies
1226
01:24:20.989 --> 01:24:25.800
cross the threshold from theoretically accessible to permanently lost. The
1227
01:24:25.880 --> 01:24:29.819
universe is not opening up to exploration. It is closing down.
1228
01:24:30.500 --> 01:24:34.600
It is pulling its galaxies apart, stretching the connections between
1229
01:24:34.640 --> 01:24:38.020
them until they snap. and leaving each island of matter
1230
01:24:38.140 --> 01:24:41.180
stranded in a void that grows without limit. The real
1231
01:24:41.260 --> 01:24:44.100
question is no longer how far it is between galaxies.
1232
01:24:44.939 --> 01:24:47.560
The real question is what it means to live in
1233
01:24:47.600 --> 01:24:51.470
a cosmos where the distances between structures are not merely
1234
01:24:51.520 --> 01:24:55.590
large but actively growing, where the very fabric of reality
1235
01:24:55.649 --> 01:25:00.229
conspires to isolate every galaxy from every other galaxy, and
1236
01:25:00.270 --> 01:25:03.189
where the most fundamental laws of physics guarantee that this
1237
01:25:03.329 --> 01:25:07.029
isolation will only deepen with time. That question belongs to
1238
01:25:07.069 --> 01:25:11.619
the final reckoning, and its answer is not comforting. Everything
1239
01:25:11.659 --> 01:25:15.300
you have heard so far has been factual. The distances
1240
01:25:15.359 --> 01:25:19.800
are real. The emptiness is measured. The expansion is confirmed.
1241
01:25:20.479 --> 01:25:24.890
The unreachability is calculated from the most fundamental equations in physics.
1242
01:25:25.859 --> 01:25:29.350
None of it is speculation. None of it is exaggeration.
1243
01:25:29.829 --> 01:25:34.930
The universe really is this empty, this vast. this structurally
1244
01:25:35.029 --> 01:25:39.090
hostile to connection between its largest inhabitants. And now it
1245
01:25:39.170 --> 01:25:42.329
is time to sit with what that means. The human
1246
01:25:42.409 --> 01:25:46.729
mind is built to find patterns, to detect relationships, to
1247
01:25:46.770 --> 01:25:49.989
assume that visible things are connected to one another. We
1248
01:25:50.050 --> 01:25:52.390
see a sky full of stars and we draw lines
1249
01:25:52.449 --> 01:25:57.079
between them, inventing constellations, imagining a ceiling of light that
1250
01:25:57.159 --> 01:26:00.720
wraps around us like a blanket. We see photographs of
1251
01:26:00.779 --> 01:26:04.560
galaxies scattered across deep field images, and we imagine a
1252
01:26:04.640 --> 01:26:09.050
cosmos buzzing with proximity. A universe where the distance between
1253
01:26:09.130 --> 01:26:13.170
objects is large but fundamentally navigable. A place where the
1254
01:26:13.250 --> 01:26:17.350
sheer abundance of galaxies implies some form of cosmic togetherness.
1255
01:26:18.350 --> 01:26:22.840
Two trillion galaxies. Surely a universe with two trillion galaxies
1256
01:26:22.920 --> 01:26:26.659
is a full universe. Surely it is a connected universe.
1257
01:26:27.520 --> 01:26:31.180
Surely the existence of so many structures means that isolation
1258
01:26:31.239 --> 01:26:35.020
is impossible at the grandest scale. The word galaxy itself
1259
01:26:35.140 --> 01:26:37.920
comes from the Greek for milk, a reference to the
1260
01:26:37.960 --> 01:26:41.600
pale band of the Milky Way. For most of human history,
1261
01:26:42.020 --> 01:26:45.430
we did not even know that other galaxies existed. The
1262
01:26:45.520 --> 01:26:48.609
idea that the universe contained structures beyond our own was
1263
01:26:48.670 --> 01:26:52.869
confirmed barely a century ago. We have known about intergalactic
1264
01:26:52.930 --> 01:26:56.210
distance for less than a hundred years. We are still
1265
01:26:56.270 --> 01:27:00.199
learning to feel its weight. It does not, And that
1266
01:27:00.260 --> 01:27:02.659
is the revelation that sits at the heart of everything
1267
01:27:02.699 --> 01:27:06.050
this story has been building toward. The universe contains two
1268
01:27:06.170 --> 01:27:09.930
trillion galaxies, and it is lonely. Not lonely in the
1269
01:27:09.970 --> 01:27:15.069
sentimental sense, lonely in the structural sense. Lonely in the
1270
01:27:15.109 --> 01:27:18.479
way an archipelago of islands scattered across an ocean ten
1271
01:27:18.560 --> 01:27:23.079
thousand times wider than any island is lonely. The islands exist.
1272
01:27:23.720 --> 01:27:28.180
They are real. Some of them are enormous. containing billions
1273
01:27:28.220 --> 01:27:32.579
of inhabitants and complex ecosystems. But the ocean between them
1274
01:27:32.640 --> 01:27:36.960
is so vast, so deep, and so featureless that the
1275
01:27:37.079 --> 01:27:40.920
islands might as well be separate worlds. No bridge can
1276
01:27:40.979 --> 01:27:45.220
span the water. No ship can survive the crossing. No
1277
01:27:45.300 --> 01:27:47.840
message in a bottle can drift from one shore to
1278
01:27:47.880 --> 01:27:51.979
another before the currents carry it into oblivion. The islands
1279
01:27:52.020 --> 01:27:54.899
are there, and they are alone, and the ocean does
1280
01:27:54.939 --> 01:27:59.369
not care. This analogy like all analogies for cosmic scale,
1281
01:27:59.869 --> 01:28:03.189
eventually breaks under its own weight. Because at least on Earth,
1282
01:28:03.689 --> 01:28:07.350
islands in the same ocean share the same water. Currents
1283
01:28:07.430 --> 01:28:13.069
connect them, however weakly. Seabirds carry seeds between shores. Driftwood
1284
01:28:13.180 --> 01:28:16.600
travels from one coast to another. The ocean is a medium.
1285
01:28:17.180 --> 01:28:23.220
It transmits. It connects. Even across vast distances. The intergalactic
1286
01:28:23.260 --> 01:28:27.659
void is not a medium. It transmits nothing. It connects nothing.
1287
01:28:28.119 --> 01:28:31.439
It is not a substance between two objects. It is
1288
01:28:31.500 --> 01:28:36.109
the absence of substance, stretching across distances that make every
1289
01:28:36.229 --> 01:28:40.840
earthly ocean look like a puddle. The archipelago analysis captures
1290
01:28:40.880 --> 01:28:44.659
the loneliness. It cannot capture the totality of the severance.
1291
01:28:45.539 --> 01:28:49.899
This is the architecture of the universe. Not a deficiency
1292
01:28:49.960 --> 01:28:54.619
in it. Not a problem awaiting a solution. The architecture itself.
1293
01:28:55.399 --> 01:28:58.439
The cosmos was not built and then emptied. It was
1294
01:28:58.539 --> 01:29:03.109
built from emptiness. The quantum fluctuations that rippled through the
1295
01:29:03.149 --> 01:29:08.729
infant universe 13.8 billion years ago created the initial conditions
1296
01:29:08.789 --> 01:29:12.770
for both structure and absence, and gravity spent the next
1297
01:29:12.770 --> 01:29:17.220
13 billion years amplifying both. It pulled matter into filaments
1298
01:29:17.260 --> 01:29:20.439
and nodes where galaxies could form, and it drained that
1299
01:29:20.500 --> 01:29:24.199
matter from the regions in between, leaving behind voids so
1300
01:29:24.300 --> 01:29:27.159
thorough that they now constitute 80% of the universe by volume.
1301
01:29:29.270 --> 01:29:32.449
The structure and the emptiness grew together. They are the
1302
01:29:32.510 --> 01:29:36.930
same process viewed from two directions. You cannot have galaxies
1303
01:29:36.970 --> 01:29:39.710
without the voids that surrendered their matter to build them.
1304
01:29:40.189 --> 01:29:43.560
You cannot have the cosmic web without the empty bubbles
1305
01:29:43.640 --> 01:29:48.699
it surrounds. This means that intergalactic isolation is not an
1306
01:29:48.760 --> 01:29:51.960
incidental feature of a universe that happens to be large.
1307
01:29:52.859 --> 01:29:55.609
It is a necessary consequence of the physics that made
1308
01:29:55.670 --> 01:30:00.819
galaxies possible in the first place. The same gravitational instability
1309
01:30:00.880 --> 01:30:03.779
that formed the Milky Way also excavated the void that
1310
01:30:03.819 --> 01:30:07.079
separates it from its neighbours. The same process that built
1311
01:30:07.159 --> 01:30:10.399
Andromeda also ensured that the space between Andromeda and us
1312
01:30:10.880 --> 01:30:14.479
would be swept nearly clean of matter. Every galaxy in
1313
01:30:14.520 --> 01:30:17.789
the universe exists because a surrounding region was emptied to
1314
01:30:17.850 --> 01:30:21.449
feed it. The birth of every island required the deepening
1315
01:30:21.489 --> 01:30:24.930
of the ocean around it. Isolation is not the price
1316
01:30:24.970 --> 01:30:29.149
of existence, it is the mechanism of existence. Galaxies are
1317
01:30:29.189 --> 01:30:32.850
born isolated, and the universe ensures they stay that way.
1318
01:30:33.550 --> 01:30:36.569
This is a difficult idea to absorb because it violates
1319
01:30:36.630 --> 01:30:41.189
something deep in human psychology. We are social creatures. We
1320
01:30:41.229 --> 01:30:45.960
evolved in groups. Our survival depended on connection, on cooperation,
1321
01:30:46.420 --> 01:30:48.720
on the ability to reach others when we needed help.
1322
01:30:49.500 --> 01:30:52.560
The idea that the universe might be fundamentally structured to
1323
01:30:52.600 --> 01:30:57.720
prevent connection between its largest inhabitants feels almost hostile. It
1324
01:30:57.779 --> 01:31:02.439
is not hostile. The universe has no intentions, but the
1325
01:31:02.500 --> 01:31:06.979
effect is the same. The physics that governs cosmic structure
1326
01:31:07.060 --> 01:31:10.609
produces isolation as reliably as the physics that governs chemistry
1327
01:31:10.670 --> 01:31:14.729
produces water from hydrogen and oxygen. It is not a choice.
1328
01:31:15.510 --> 01:31:19.090
It is a consequence. And the consequence is a cosmos,
1329
01:31:19.729 --> 01:31:24.689
where the most magnificent objects in existence, galaxies containing hundreds
1330
01:31:24.729 --> 01:31:28.250
of billions of suns and trillions of worlds, are each
1331
01:31:28.310 --> 01:31:31.270
confined to their own patch of space with no meaningful
1332
01:31:31.329 --> 01:31:35.069
ability to interact with the others. Consider what this means
1333
01:31:35.130 --> 01:31:38.130
for the question that haunts every discussion of cosmic scale.
1334
01:31:38.949 --> 01:31:42.439
Are we alone? The question is usually framed in terms
1335
01:31:42.500 --> 01:31:47.659
of biology. Is there life elsewhere? Are there other civilizations?
1336
01:31:48.560 --> 01:31:51.020
Other minds looking up at other skies and wondering the
1337
01:31:51.060 --> 01:31:55.220
same things, but the distance between galaxies reframes the question
1338
01:31:55.260 --> 01:31:57.760
in a way that cuts deeper than biology ever could.
1339
01:31:58.630 --> 01:32:01.710
Even if life is common, even if every galaxy teems
1340
01:32:01.750 --> 01:32:05.899
with civilizations, even if intelligence is a routine product of
1341
01:32:05.960 --> 01:32:09.979
cosmic evolution, the distances ensure that none of it matters
1342
01:32:10.020 --> 01:32:14.920
in any practical sense. Civilizations separated by millions of light
1343
01:32:14.960 --> 01:32:18.520
years cannot talk to each other, they cannot visit each other,
1344
01:32:19.119 --> 01:32:22.649
they cannot confirm each other's existence within any time frame
1345
01:32:22.689 --> 01:32:25.859
that matters to either party. They are alone in every
1346
01:32:25.930 --> 01:32:28.050
way that the word alone has ever meant to any
1347
01:32:28.109 --> 01:32:32.750
conscious being. A civilization in a galaxy 200 million light
1348
01:32:32.770 --> 01:32:37.289
years away could be the most advanced, most compassionate, most
1349
01:32:37.430 --> 01:32:41.590
curious society the universe has ever produced. It could have
1350
01:32:41.649 --> 01:32:45.609
solved every problem that plagues our species. It could have
1351
01:32:45.630 --> 01:32:48.609
built wonders that would make our greatest achievements look like
1352
01:32:48.680 --> 01:32:52.739
children's drawings. And we would never know. Not because our
1353
01:32:52.779 --> 01:32:56.779
telescopes are too weak, not because our radios are too quiet.
1354
01:32:57.560 --> 01:33:01.239
Because 200 million light years of expanding void sits between us,
1355
01:33:01.899 --> 01:33:04.199
and nothing in the known laws of physics can carry
1356
01:33:04.239 --> 01:33:07.260
a meaningful signal across that distance within the lifetime of
1357
01:33:07.399 --> 01:33:12.140
either civilization. The void does not care how advanced either
1358
01:33:12.180 --> 01:33:16.060
party is. It does not yield to ingenuity or determination.
1359
01:33:16.699 --> 01:33:22.060
It is indifferent, absolute, and permanent. This asymmetry between knowledge
1360
01:33:22.100 --> 01:33:25.970
and access is one of the most philosophically disorienting features
1361
01:33:26.029 --> 01:33:29.789
of modern cosmology. We know the galaxies are there. We
1362
01:33:29.810 --> 01:33:33.449
can count them. We can measure their masses, their star
1363
01:33:33.479 --> 01:33:38.500
formation rates, their chemical compositions. We can study their evolution
1364
01:33:38.560 --> 01:33:42.340
across billions of years of cosmic history. We know more
1365
01:33:42.399 --> 01:33:45.960
about the observable universe than any previous generation of humans
1366
01:33:46.020 --> 01:33:50.359
could have imagined. And all of that knowledge changes nothing
1367
01:33:50.979 --> 01:33:55.850
about the fundamental isolation. Knowing a galaxy exists 200 million
1368
01:33:55.869 --> 01:33:58.329
light years away does not bring it one meter closer.
1369
01:33:59.180 --> 01:34:02.479
Understanding the physics of cosmic expansion does not slow the
1370
01:34:02.539 --> 01:34:06.399
expansion by a single kilometer per second. The knowledge and
1371
01:34:06.439 --> 01:34:09.779
the distance coexist without the knowledge affecting the distance in
1372
01:34:09.859 --> 01:34:13.670
any way. We are the most informed prisoners any universe
1373
01:34:13.710 --> 01:34:17.630
has ever produced. This is the cruelty buried inside the
1374
01:34:17.710 --> 01:34:21.029
beauty of every deep field image. When you look at
1375
01:34:21.050 --> 01:34:24.510
a photograph showing thousands of galaxies, you are looking at
1376
01:34:24.649 --> 01:34:28.069
thousands of islands that will never know one another. Each
1377
01:34:28.149 --> 01:34:31.380
galaxy in that image is a complete world unto itself,
1378
01:34:31.880 --> 01:34:36.600
containing hundreds of billions of stars, trillions of planets, and
1379
01:34:36.659 --> 01:34:40.640
possibly countless forms of life and intelligence. And each one
1380
01:34:40.699 --> 01:34:43.600
is sealed inside a bubble of distance and expansion that
1381
01:34:43.670 --> 01:34:47.369
renders it permanently inaccessible to every other galaxy in the frame.
1382
01:34:48.029 --> 01:34:52.979
The image shows proximity. The physics guarantees isolation. The beauty
1383
01:34:53.020 --> 01:34:56.100
and the horror occupy the same frame. And there is
1384
01:34:56.140 --> 01:35:00.119
a deeper irony still. The very technology that allows us
1385
01:35:00.170 --> 01:35:04.529
to see those distant galaxies, the telescopes and instruments that
1386
01:35:04.569 --> 01:35:08.850
reveal the cosmic web in all its sprawling complexity, also
1387
01:35:08.909 --> 01:35:12.149
confirms that we can never touch any of it. Every
1388
01:35:12.210 --> 01:35:16.399
improvement in observational capability shows us more of the universe
1389
01:35:16.960 --> 01:35:20.920
and simultaneously demonstrates that more of it is unreachable. The
1390
01:35:20.939 --> 01:35:24.020
James Webb Space Telescope can peer deeper into the cosmos
1391
01:35:24.060 --> 01:35:28.010
than any instrument before it, resolving galaxies that formed when
1392
01:35:28.050 --> 01:35:31.970
the universe was less than 500 million years old. Each
1393
01:35:32.010 --> 01:35:35.350
of those galaxies is a real place, a collection of
1394
01:35:35.470 --> 01:35:38.409
stars and worlds that existed and evolved and may have
1395
01:35:38.449 --> 01:35:42.739
produced wonders beyond our imagination. and every single one of
1396
01:35:42.779 --> 01:35:45.520
them is so far away that even light from their
1397
01:35:45.560 --> 01:35:49.470
present state will never reach us. We are building better
1398
01:35:49.529 --> 01:35:52.909
windows onto a cosmos that is closing its doors, and
1399
01:35:52.949 --> 01:35:57.409
the isolation is deepening. The cosmic web is not permanent.
1400
01:35:58.229 --> 01:36:01.880
It is a transient structure, a phase in the universe's
1401
01:36:01.939 --> 01:36:05.239
evolution that exists only because the cosmos is still young
1402
01:36:05.279 --> 01:36:08.479
enough for gravity to maintain the connections between its parts.
1403
01:36:08.989 --> 01:36:13.630
Dark energy is slowly winning the contest. The voids are expanding.
1404
01:36:14.029 --> 01:36:18.210
The filaments are thinning. The distances between galaxy groups are
1405
01:36:18.229 --> 01:36:22.510
increasing with every passing moment, accelerating under the influence of
1406
01:36:22.569 --> 01:36:25.789
a force that shows no sign of weakening or reversing.
1407
01:36:26.390 --> 01:36:30.060
The cosmic web that currently connects galaxy clusters across hundreds
1408
01:36:30.100 --> 01:36:33.659
of millions of light years will eventually dissolve, its filaments
1409
01:36:33.720 --> 01:36:38.279
stretched beyond coherence, its walls dispersed into the expanding void.
1410
01:36:39.020 --> 01:36:42.880
The nodes will persist for a time, gravitationally bound clusters
1411
01:36:42.920 --> 01:36:46.590
of galaxies that hold themselves together against the tide. But
1412
01:36:46.649 --> 01:36:50.729
even those clusters are not eternal. Given enough time, dark
1413
01:36:50.810 --> 01:36:53.630
energy will push apart everything that is not bound into
1414
01:36:53.670 --> 01:36:58.239
a single gravitationally locked system. The Local Group is our system.
1415
01:36:58.840 --> 01:37:02.359
Recent studies have complicated the long-held certainty that the Milky
1416
01:37:02.420 --> 01:37:08.359
Way and Andromeda will collide. Research published in 2025 incorporating
1417
01:37:08.420 --> 01:37:12.069
updated data from the Gaia and Hubble Space Telescopes, and
1418
01:37:12.109 --> 01:37:15.949
accounting for the gravitational influence of the Large Magellanic Cloud
1419
01:37:15.989 --> 01:37:19.909
and the Triangulum Galaxy, found that a head-on collision within
1420
01:37:19.949 --> 01:37:23.489
the next 10 billion years may be only about 50% likely.
1421
01:37:24.289 --> 01:37:28.880
A subsequent 2026 analysis using the latest proper motion measurements
1422
01:37:29.460 --> 01:37:33.739
raised the merger probability back to approximately 90%, with a
1423
01:37:33.800 --> 01:37:38.149
median merger time of roughly 6.5 billion years. The outcome
1424
01:37:38.189 --> 01:37:42.529
remains an active area of scientific investigation. But whether the
1425
01:37:42.590 --> 01:37:45.909
merger happens in 5 billion years or 10, whether the
1426
01:37:45.949 --> 01:37:49.989
two spirals collide directly or drift into a slow orbital decay,
1427
01:37:50.680 --> 01:37:53.920
the eventual result is the same. The galaxies of the
1428
01:37:53.960 --> 01:37:58.560
local group will combine. Their stars will mingle. Their dark
1429
01:37:58.659 --> 01:38:02.039
matter halos will merge. And over the course of tens
1430
01:38:02.079 --> 01:38:05.430
of billions of years, the entire group will settle into
1431
01:38:05.470 --> 01:38:09.539
a single massive structure. Astronomers have already named this future
1432
01:38:09.579 --> 01:38:14.760
galaxy Milkomeda. Milkomeda will be enormous. It will contain the
1433
01:38:14.800 --> 01:38:20.590
combined stellar populations of the Milky Way, Andromeda, Triangulum, and
1434
01:38:20.649 --> 01:38:23.750
every dwarf galaxy in the local group. It will be
1435
01:38:23.789 --> 01:38:28.550
a giant elliptical galaxy. Its elegant spiral arms are raised
1436
01:38:28.609 --> 01:38:32.949
by the chaotic violence of repeated mergers, its stars orbiting
1437
01:38:32.989 --> 01:38:37.250
in random directions around a massive central core. It will be,
1438
01:38:37.390 --> 01:38:42.829
by any measure, a spectacular object. And it will be utterly, permanently,
1439
01:38:43.449 --> 01:38:46.829
cosmically alone. Think about what that sky will look like.
1440
01:38:47.350 --> 01:38:51.130
An observer standing on a planet in Milkomeda perhaps orbiting
1441
01:38:51.170 --> 01:38:54.449
a star in the merged galaxy's outer halo, would look
1442
01:38:54.529 --> 01:38:58.390
upward and see a spectacular band of stars, the dense
1443
01:38:58.489 --> 01:39:01.949
core of the elliptical galaxy stretching across their sky in
1444
01:39:02.000 --> 01:39:05.579
a river of light. The view inward would be magnificent,
1445
01:39:06.079 --> 01:39:09.680
but the view outward, beyond the galaxy's edge, would be
1446
01:39:09.720 --> 01:39:14.100
the most terrifying sight any conscious being could confront. Nothing.
1447
01:39:14.949 --> 01:39:17.649
Not the blackness of a cloudy night where you know
1448
01:39:17.710 --> 01:39:23.039
the stars are hiding behind the weather, A permanent, structural emptiness.
1449
01:39:23.920 --> 01:39:28.079
A void that contains no objects, emits no signals, and
1450
01:39:28.100 --> 01:39:32.399
offers no evidence that anything exists beyond the galaxy's gravitational boundary.
1451
01:39:33.020 --> 01:39:35.939
The sky would end at the edge of Milkomeda. Beyond
1452
01:39:36.000 --> 01:39:41.529
that edge, in every direction, forever darkness. By the time
1453
01:39:41.569 --> 01:39:45.210
Milkomeda has fully formed, roughly 10 billion years from now,
1454
01:39:45.869 --> 01:39:49.279
every galaxy outside the local group will be receding, at
1455
01:39:49.470 --> 01:39:54.310
ever-increasing velocities. The nearest galaxy clusters will have drifted hundreds
1456
01:39:54.350 --> 01:39:57.250
of millions of light-years farther away than they are today.
1457
01:39:58.050 --> 01:40:00.970
The filaments of the cosmic web connecting our corner of
1458
01:40:01.010 --> 01:40:04.939
the universe to neighbouring structures will have stretched beyond recognition,
1459
01:40:05.520 --> 01:40:10.600
their matter dispersed into the expanding void. Within 100 to
1460
01:40:10.600 --> 01:40:15.060
150 billion years, every galaxy beyond the Local Group will
1461
01:40:15.079 --> 01:40:18.180
have crossed the cosmic event horizon. Their light will have
1462
01:40:18.260 --> 01:40:22.739
redshifted to wavelength so long that no conceivable instrument could
1463
01:40:22.779 --> 01:40:26.699
detect them. The cosmic microwave background itself will have faded
1464
01:40:26.760 --> 01:40:31.369
beyond detectability. Its photons stretched to wavelength so long and
1465
01:40:31.409 --> 01:40:35.609
its intensity diluted so thin that no instrument could distinguish
1466
01:40:35.649 --> 01:40:40.390
it from silence. A civilization arising in Milkomeda at that
1467
01:40:40.489 --> 01:40:45.079
distant epoch would inhabit a galaxy containing perhaps a trillion
1468
01:40:45.159 --> 01:40:50.590
stars surrounded by nothing Their most powerful telescopes, pointed in
1469
01:40:50.810 --> 01:40:56.449
any direction, would reveal only darkness. No other galaxies. No
1470
01:40:56.529 --> 01:41:01.850
cosmic web. No filaments or clusters or walls. No background
1471
01:41:01.909 --> 01:41:05.609
radiation from the Big Bang. Nothing that would suggest the
1472
01:41:05.710 --> 01:41:09.770
universe ever contained anything beyond their own galactic borders. They
1473
01:41:09.810 --> 01:41:13.000
would have no way of discovering that the universe is expanding,
1474
01:41:13.579 --> 01:41:16.220
because there would be no distant objects against which to
1475
01:41:16.300 --> 01:41:19.630
measure the expansion. They would have no way of inferring
1476
01:41:19.649 --> 01:41:22.180
the Big Bang, because the evidence for it would have
1477
01:41:22.199 --> 01:41:25.260
been carried beyond their horizon by the very expansion it
1478
01:41:25.340 --> 01:41:28.279
set in motion. They would look out at a cosmos
1479
01:41:28.319 --> 01:41:34.010
that appeared static, solitary and eternal, a single galaxy floating
1480
01:41:34.050 --> 01:41:37.010
in an infinite void, and they would have no reason
1481
01:41:37.050 --> 01:41:39.390
to suspect that this was not how the universe had
1482
01:41:39.430 --> 01:41:43.529
always been. They would develop their own cosmology based on
1483
01:41:43.550 --> 01:41:48.000
the only data available to them, a single galaxy. surrounded
1484
01:41:48.039 --> 01:41:53.939
by infinite empty space. No expansion, no beginning, no other structures.
1485
01:41:54.760 --> 01:41:58.659
Their physics might be brilliant, their mathematics might be flawless,
1486
01:41:59.159 --> 01:42:02.340
but their cosmology would be wrong. Not because of any
1487
01:42:02.460 --> 01:42:05.439
failure of intellect, but because the universe would have removed
1488
01:42:05.479 --> 01:42:08.689
the evidence they needed to get the right answer. We
1489
01:42:08.750 --> 01:42:10.869
know this because we can see what they will not
1490
01:42:10.930 --> 01:42:13.569
be able to see. We live at the moment when
1491
01:42:13.590 --> 01:42:17.039
the evidence is still accessible. We are the last generation
1492
01:42:17.079 --> 01:42:20.100
of observers who will ever have the full picture, or
1493
01:42:20.119 --> 01:42:22.279
at least as much of it as the current cosmic
1494
01:42:22.319 --> 01:42:27.869
horizon allows. Every generation that comes after us, every civilization
1495
01:42:27.909 --> 01:42:31.170
that arises in the deep future, will know less about
1496
01:42:31.210 --> 01:42:34.250
the universe than we do now. The cosmos is not
1497
01:42:34.329 --> 01:42:39.260
revealing itself to us. It revealed itself, briefly, and it
1498
01:42:39.340 --> 01:42:42.140
is now in the process of taking that revelation back.
1499
01:42:42.619 --> 01:42:46.159
This is not a thought experiment about some impossibly distant future.
1500
01:42:46.779 --> 01:42:49.899
This is the confirmed trajectory of the cosmos we inhabit.
1501
01:42:50.560 --> 01:42:53.819
The laws of physics, as we understand them, guarantee this outcome.
1502
01:42:54.520 --> 01:42:59.909
Dark energy is measured. Cosmic acceleration is confirmed. The expansion
1503
01:42:59.949 --> 01:43:04.090
rate is known. The math is not ambiguous. The universe
1504
01:43:04.149 --> 01:43:07.609
is headed toward a state of ultimate isolation, and nothing
1505
01:43:07.649 --> 01:43:10.789
in our current understanding of physics suggests a mechanism that
1506
01:43:10.810 --> 01:43:14.500
could prevent it. We live in a privileged moment, a
1507
01:43:14.560 --> 01:43:17.920
brief cosmological window during which the universe still wears its
1508
01:43:17.960 --> 01:43:21.779
history on its sleeve. We can see the cosmic microwave background.
1509
01:43:22.500 --> 01:43:25.220
We can map the large-scale structure of the cosmic web.
1510
01:43:25.920 --> 01:43:29.100
We can observe galaxies at distances of billions of light
1511
01:43:29.119 --> 01:43:32.590
years and reconstruct the story of cosmic evolution from the
1512
01:43:32.649 --> 01:43:35.369
Big Bang to the present. We can look out at
1513
01:43:35.470 --> 01:43:39.050
two trillion galaxies and know, at least in principle, that
1514
01:43:39.090 --> 01:43:43.250
they exist. Future inhabitants of Milkomeda will have none of
1515
01:43:43.289 --> 01:43:46.689
these advantages. The universe will have hidden its own past
1516
01:43:46.789 --> 01:43:51.470
behind an expanding wall of darkness. The greatest story ever told,
1517
01:43:52.069 --> 01:43:54.819
the story of how a hot, dense beginning gave rise
1518
01:43:54.840 --> 01:43:59.239
to stars, galaxies, planets and possibly life, will be erased
1519
01:43:59.300 --> 01:44:04.140
from the observational record. Not destroyed. Not lost to decay.
1520
01:44:04.859 --> 01:44:08.449
Simply carried beyond the reach of any observer, no matter
1521
01:44:08.489 --> 01:44:12.920
how sophisticated. no matter how determined, no matter how long
1522
01:44:12.979 --> 01:44:17.430
they wait. There is something deeply unsettling about a universe
1523
01:44:17.470 --> 01:44:21.670
that erases its own evidence, a cosmos that produces observers
1524
01:44:22.289 --> 01:44:26.270
and then, over time, removes the very data those observers
1525
01:44:26.310 --> 01:44:29.229
need to understand where they came from. It is as
1526
01:44:29.270 --> 01:44:32.770
though the universe grants a brief window of cosmic self-awareness
1527
01:44:33.289 --> 01:44:37.210
and then slowly closes the shutters, leaving each surviving galaxy
1528
01:44:37.289 --> 01:44:40.050
alone in a darkness that offers no clues about the
1529
01:44:40.109 --> 01:44:44.609
grander reality beyond. The loss would be total, not just observational,
1530
01:44:44.670 --> 01:44:50.420
but conceptual. The very ideas that define modern cosmology, expansion,
1531
01:44:50.899 --> 01:44:55.039
the Big Bang, the cosmic microwave background, the age and
1532
01:44:55.079 --> 01:44:58.939
geometry of the universe, all of these depend on observations
1533
01:44:58.979 --> 01:45:02.949
that will no longer be possible. A civilisation in Milkomeda
1534
01:45:03.420 --> 01:45:06.399
could be as intelligent as any that has ever existed,
1535
01:45:07.140 --> 01:45:12.079
could develop physics and mathematics of extraordinary sophistication, and yet
1536
01:45:12.140 --> 01:45:14.500
it would lack the raw data needed to discover the
1537
01:45:14.539 --> 01:45:18.380
most fundamental truths about the cosmos it inhabits. It would
1538
01:45:18.420 --> 01:45:21.239
be like a historian locked in a room with no documents,
1539
01:45:21.739 --> 01:45:26.939
no artifacts, no records. The history happened, the evidence was real,
1540
01:45:27.680 --> 01:45:32.140
but it has been removed permanently. by the very processes
1541
01:45:32.199 --> 01:45:35.180
that created the room in the first place. The universe
1542
01:45:35.199 --> 01:45:38.850
does not merely isolate its inhabitants from one another, it
1543
01:45:39.010 --> 01:45:42.149
isolates them from the truth. And the voids do not
1544
01:45:42.210 --> 01:45:46.770
merely separate, they define. The character of the universe is
1545
01:45:46.829 --> 01:45:49.850
not determined by the galaxies within it, but by the
1546
01:45:50.010 --> 01:45:54.560
emptiness between them. A universe with two trillion galaxies packed
1547
01:45:54.600 --> 01:45:56.939
into a volume where each one could see and reach
1548
01:45:56.979 --> 01:45:59.840
its neighbours would be a fundamentally different cosmos from the
1549
01:45:59.920 --> 01:46:03.079
one we inhabit, Ours is a universe where the dominant
1550
01:46:03.159 --> 01:46:07.920
feature is absence, where 80% of the volume contains almost nothing,
1551
01:46:08.600 --> 01:46:13.460
where the largest visible structures, galaxies spanning hundreds of thousands
1552
01:46:13.500 --> 01:46:16.899
of light years, are still dwarfed by the voids between
1553
01:46:16.939 --> 01:46:20.300
them by factors of hundreds or thousands, where even the
1554
01:46:20.340 --> 01:46:26.000
most magnificent galaxy, containing a trillion suns, occupies a space
1555
01:46:26.100 --> 01:46:29.829
so small compared to the surrounding emptiness. that it amounts
1556
01:46:29.869 --> 01:46:32.130
to a speck of light in an ocean of dark.
1557
01:46:32.609 --> 01:46:35.970
This is the terrifying truth that lies beneath every measurement
1558
01:46:36.050 --> 01:46:40.439
and every calculation. The universe is not merely big. It
1559
01:46:40.489 --> 01:46:43.840
is built from isolation. The voids are not gaps in
1560
01:46:43.859 --> 01:46:48.020
the structure. They are the structure. The galaxies are not
1561
01:46:48.060 --> 01:46:51.859
the main feature of the cosmos. They are the rare, thin,
1562
01:46:52.439 --> 01:46:56.789
luminous exceptions to a rule of overwhelming emptiness. The rule
1563
01:46:56.829 --> 01:47:00.310
is the void. The exception is the light. And the
1564
01:47:00.369 --> 01:47:04.210
exceptions are separated from one another by distances so vast,
1565
01:47:04.729 --> 01:47:09.270
through environments so barren, across timescales so long, that the
1566
01:47:09.310 --> 01:47:13.630
word separation barely begins to capture the reality. Think of
1567
01:47:13.670 --> 01:47:17.399
it this way. Every galaxy in the universe is a campfire.
1568
01:47:18.180 --> 01:47:22.520
Some are small, flickering things. Others are roaring bonfires throwing
1569
01:47:22.600 --> 01:47:26.510
light across hundreds of thousands of light-years. But between every
1570
01:47:26.550 --> 01:47:30.329
campfire and every other campfire stretches a darkness so deep
1571
01:47:30.369 --> 01:47:33.310
and so wide that no one sitting at any fire
1572
01:47:33.350 --> 01:47:36.329
can see the glow of any other. The fires burn
1573
01:47:36.390 --> 01:47:41.390
in absolute solitude. Each one heats its own small circle
1574
01:47:41.409 --> 01:47:46.350
of space. Each one illuminates its own tiny sphere of matter.
1575
01:47:46.810 --> 01:47:50.729
And beyond that sphere, in every direction, the darkness goes
1576
01:47:50.810 --> 01:47:54.770
on forever. The campfires are real. The warmth is real.
1577
01:47:55.390 --> 01:47:58.630
The light is real. But the darkness between them is
1578
01:47:58.770 --> 01:48:03.550
so much vaster, so much older, so much more fundamental
1579
01:48:03.590 --> 01:48:06.670
to the nature of the cosmos, that the fires begin
1580
01:48:06.710 --> 01:48:12.199
to seem like accidents. Brief, bright, improbable interruptions in a
1581
01:48:12.359 --> 01:48:16.920
universe that is, at its core, made of dark. This
1582
01:48:17.000 --> 01:48:21.420
is not nihilism. It is observation. The universe does not
1583
01:48:21.539 --> 01:48:24.920
owe us connection. It does not owe us neighbours. It
1584
01:48:24.939 --> 01:48:27.479
does not owe us a cosmos that feels warm or
1585
01:48:27.600 --> 01:48:33.090
full or navigable. It simply is what it is. A vast, expanding,
1586
01:48:33.609 --> 01:48:38.560
overwhelmingly empty structure. in which matter occasionally organizes itself into
1587
01:48:38.659 --> 01:48:43.800
brief concentrations of complexity that call themselves galaxies. Those galaxies
1588
01:48:43.859 --> 01:48:47.560
are real. The stars within them burn with genuine fury.
1589
01:48:48.270 --> 01:48:52.409
The planets that orbit those stars host genuine chemistry. And
1590
01:48:52.470 --> 01:48:55.569
on at least one of those planets, the chemistry became
1591
01:48:55.670 --> 01:48:59.029
complicated enough to look upward and ask questions about what
1592
01:48:59.109 --> 01:49:03.010
lies beyond. The fact that the answer is mostly darkness
1593
01:49:03.449 --> 01:49:06.640
does not diminish the questions. but it does reshape the
1594
01:49:06.680 --> 01:49:10.279
meaning of the asking. Perhaps the most haunting aspect of
1595
01:49:10.319 --> 01:49:14.409
this isolation is its silence. The void between galaxies does
1596
01:49:14.470 --> 01:49:18.289
not roar or howl or whisper. It produces no sound,
1597
01:49:18.590 --> 01:49:23.750
no vibration, no signal. It is the quietest environment in existence.
1598
01:49:24.600 --> 01:49:27.720
A silence so absolute that it makes the vacuum of
1599
01:49:27.859 --> 01:49:32.800
interstellar space seem noisy by comparison. At least within a galaxy,
1600
01:49:33.319 --> 01:49:38.979
there are pulsars ticking, magnetars screaming, supernovae thundering across the
1601
01:49:39.039 --> 01:49:43.979
electromagnetic spectrum. Between galaxies there is only the faintest hiss
1602
01:49:44.039 --> 01:49:48.340
of the cosmic microwave background, growing quieter by the epoch,
1603
01:49:49.060 --> 01:49:52.079
fading toward a silence that will one day be complete.
1604
01:49:52.960 --> 01:49:56.000
The void is not just empty of matter. It is
1605
01:49:56.180 --> 01:50:00.199
empty of information. It is empty of story. It is
1606
01:50:00.239 --> 01:50:02.840
the place where the narrative of the cosmos ends and
1607
01:50:02.859 --> 01:50:06.750
the blankness begins. We sit at one of those campfires,
1608
01:50:07.350 --> 01:50:12.180
the Milky Way. 400 billion stars burning in a spiral
1609
01:50:12.220 --> 01:50:18.239
of light and gravity. Planets orbiting inhabitable zones. Complex chemistry
1610
01:50:18.279 --> 01:50:21.479
assembling itself into life on at least one world, and
1611
01:50:21.539 --> 01:50:27.979
possibly on billions. Intelligence emerging, looking upward, building telescopes, mapping
1612
01:50:28.020 --> 01:50:32.310
the cosmos, asking the oldest question, is anyone else out there?
1613
01:50:33.109 --> 01:50:37.500
The answer... as far as intergalactic distance is concerned, is
1614
01:50:37.539 --> 01:50:40.510
that it does not matter. Even if the answer is yes,
1615
01:50:41.310 --> 01:50:45.050
even if every galaxy contains a civilization, even if the
1616
01:50:45.170 --> 01:50:48.069
universe is saturated with life from one end of the
1617
01:50:48.130 --> 01:50:52.289
observable volume to the other, the distances ensure that each
1618
01:50:52.369 --> 01:50:56.699
civilization sits at its own campfire, warming its hands against
1619
01:50:56.739 --> 01:51:00.500
a cold that extends in every direction without limit. The
1620
01:51:00.520 --> 01:51:04.020
campfires cannot see each other, they cannot reach each other,
1621
01:51:04.789 --> 01:51:08.329
They cannot confirm that the others exist. They burn alone,
1622
01:51:08.869 --> 01:51:12.199
separated by the deepest and most permanent isolation the laws
1623
01:51:12.260 --> 01:51:16.939
of physics can produce. Two trillion galaxies, each one a
1624
01:51:16.979 --> 01:51:21.199
world unto itself, each one containing enough stars and planets
1625
01:51:21.260 --> 01:51:25.279
to make the question of cosmic companionship feel urgent and answerable.
1626
01:51:26.079 --> 01:51:29.590
And between every pair of them, a void so vast,
1627
01:51:30.149 --> 01:51:34.880
so empty and so relentlessly expanding, that the question becomes
1628
01:51:35.020 --> 01:51:37.899
not whether someone is out there, but whether out there
1629
01:51:37.960 --> 01:51:41.739
even means anything when the distances involved exceed the ability
1630
01:51:41.779 --> 01:51:44.619
of light itself to bridge them in any meaningful time.
1631
01:51:45.020 --> 01:51:49.399
The universe is full of galaxies, it is empty of connection,
1632
01:51:49.880 --> 01:51:53.079
and that may be the most unsettling truth that astronomy,
1633
01:51:53.500 --> 01:51:56.470
in all its centuries of looking upward, has ever had
1634
01:51:56.520 --> 01:52:00.510
the precision to reveal. The distance between galaxies is not
1635
01:52:00.569 --> 01:52:04.130
merely large, It is the defining feature of the cosmos.
1636
01:52:04.689 --> 01:52:07.930
It is the architecture of reality. It is the silence
1637
01:52:07.989 --> 01:52:10.569
between the notes in a symphony that plays across a
1638
01:52:10.649 --> 01:52:13.470
stage too wide for any audience to hear more than
1639
01:52:13.529 --> 01:52:17.449
its own small section. We are here. We are real.
1640
01:52:18.100 --> 01:52:22.500
Our campfire burns. And the darkness around it stretches farther
1641
01:52:22.539 --> 01:52:25.600
than we will ever be able to see. Farther than
1642
01:52:25.659 --> 01:52:28.850
we will ever be able to reach. Farther than any
1643
01:52:28.939 --> 01:52:32.329
signal we send will ever travel before the expanding void
1644
01:52:32.449 --> 01:52:37.109
swallows it into silence. The galaxies are out there, trillions
1645
01:52:37.170 --> 01:52:39.699
of them, each one as real and as full of
1646
01:52:39.779 --> 01:52:42.920
possibility as our own, and every one of them is marooned,
1647
01:52:43.479 --> 01:52:46.439
as we are marooned, on an island of light in
1648
01:52:46.479 --> 01:52:48.789
an ocean of dark that has no far shore.