Trascrizione completa di StarTalk Podcast_ Cosmic Queries – A Taste of Space_ with Matt O_Dowd and Neil deGrasse Tyson

You've got to dig for it. What? 76 00:03:45.129 --> 00:03:45.680 Not all diamond. 77 00:03:46.060 --> 00:03:48.719 And the other thing is diamonds aren't that rare anyway, 78 00:03:48.780 --> 00:03:49.439 even on Earth. 79 00:03:49.560 --> 00:03:50.840 I think we, you know. 80 00:03:51.280 --> 00:03:52.240 Idolize them too much? 81 00:03:52.740 --> 00:03:55.500 Yeah, I mean, they're not that uncommon. So we've got 82 00:03:55.520 --> 00:03:57.180 the diamond, and like I said, in New York City, 83 00:03:57.199 --> 00:04:00.219 there are no reptiles the size of buildings. But if 84 00:04:00.240 --> 00:04:02.879 you live in a small town, you know, T-Rex would 85 00:04:02.919 --> 00:04:05.180 be bigger than your house. 86 00:04:05.240 --> 00:04:07.539 I know you know this because I think you assembled 87 00:04:07.580 --> 00:04:10.009 the T-Rex skeleton yourself at the museum. 88 00:04:10.389 --> 00:04:12.629 I don't know. It was a kit. Put it together. Exactly. 89 00:04:12.830 --> 00:04:17.670 Well, so reptiles descended from... the same ancestor as dinosaurs, 90 00:04:17.709 --> 00:04:18.810 but dinosaurs themselves- I. 91 00:04:18.769 --> 00:04:19.649 Mean, modern reptiles, yeah. 92 00:04:19.689 --> 00:04:22.889 Yeah, were not reptiles. As far as I understand, they 93 00:04:22.990 --> 00:04:27.699 are basically closely related to birds. In fact, birds are dinosaurs, really. 94 00:04:27.860 --> 00:04:30.439 Aren't birds more closely related to the dinosaurs than modern 95 00:04:30.459 --> 00:04:30.959 reptiles are? 96 00:04:31.839 --> 00:04:36.199 My understanding really from the phylogenetic tree at the American 97 00:04:36.240 --> 00:04:39.810 Museum of Natural History is that birds and dinosaurs are 98 00:04:40.170 --> 00:04:40.889 really the same thing. 99 00:04:41.790 --> 00:04:43.810 Birds are the only surviving. Yeah, my issue was the reptiles. 100 00:04:43.970 --> 00:04:46.370 That's what I'm saying. So everyone's talking about birds being 101 00:04:46.389 --> 00:04:49.589 the descendants of dinosaurs without mentioning the crocodile. And is 102 00:04:49.610 --> 00:04:51.740 that true? I don't know. 103 00:04:52.160 --> 00:04:53.720 Crocodile is the worst bird. 104 00:04:54.040 --> 00:04:54.860 It is, yeah. 105 00:04:54.939 --> 00:04:56.939 It's a famously terrible bird. 106 00:04:56.959 --> 00:05:02.040 But neither of us is a paleobiologist. So all I 107 00:05:02.060 --> 00:05:05.350 can say is, there were never dinosaurs the size of 108 00:05:05.410 --> 00:05:07.870 New York City buildings. That's all I'm saying. Right. 109 00:05:07.930 --> 00:05:09.769 All I want to say is, is there a limit 110 00:05:09.990 --> 00:05:14.689 to this universe? I would say absolutely yes, in that 111 00:05:14.730 --> 00:05:17.240 not everything that can exist does, but. 112 00:05:17.139 --> 00:05:18.319 So many things. Well, how do you know that? 113 00:05:19.600 --> 00:05:21.459 It's an educated guess. 114 00:05:21.540 --> 00:05:25.000 Name something that can exist that you think doesn't. 115 00:05:25.279 --> 00:05:30.970 Name something that can exist. Well, for example, the mathematics of, say, 116 00:05:32.569 --> 00:05:37.850 of relativity describe things like wormholes and quantum mechanics says 117 00:05:37.889 --> 00:05:38.769 it's tachyons. 118 00:05:39.810 --> 00:05:41.829 You think Star Trek isn't real? 119 00:05:42.129 --> 00:05:42.199 No. 120 00:05:44.779 --> 00:05:46.879 Like if I admit I can't admit a tachyon pulse? 121 00:05:47.939 --> 00:05:51.009 I would say an infinite universe contains an infinite number 122 00:05:51.050 --> 00:05:53.910 of things, but it doesn't contain everything that you can imagine. 123 00:05:54.860 --> 00:05:57.579 I said the laws of physics still have to be obeyed. 124 00:05:58.459 --> 00:06:00.579 Well, so I'm with you on that. So you're not 125 00:06:00.600 --> 00:06:03.889 gonna have an Empire State Building sized reptile. 126 00:06:04.069 --> 00:06:04.230 Exactly. 127 00:06:04.250 --> 00:06:06.670 Because it can't hold itself up. Exactly. With a very interesting, 128 00:06:06.689 --> 00:06:08.029 you know about this, they teach this, I don't think 129 00:06:08.050 --> 00:06:12.430 they teach this outside of like physics 101. Right. So 130 00:06:12.949 --> 00:06:20.079 as you get bigger. Yeah. Your volume grows, your weight 131 00:06:20.120 --> 00:06:23.110 goes up according to your volume. But the strength of 132 00:06:23.139 --> 00:06:27.970 your limbs goes up only according to the cross-sectional area. 133 00:06:28.529 --> 00:06:30.470 So it's a matter of area versus volume. 134 00:06:30.569 --> 00:06:31.850 So Godzilla is. 135 00:06:32.069 --> 00:06:34.310 Godzilla would collapse under his own weight into a puddle 136 00:06:34.350 --> 00:06:40.730 of guts. Yes, correct. Even if it was irradiated, just because... Oh, 137 00:06:40.850 --> 00:06:43.689 he was irradiated. Is that helpful? 138 00:06:43.769 --> 00:06:45.889 That changes the volume area thing completely. 139 00:06:46.350 --> 00:06:47.629 Does it affect it at all? 140 00:06:47.689 --> 00:06:53.589 So it's why big animals... heavy animals have thicker legs. 141 00:06:54.529 --> 00:06:56.990 So you can't just scale up an insect and make 142 00:06:57.029 --> 00:06:59.189 them this big. Because their body weight. 143 00:06:59.209 --> 00:07:00.350 That is great news. 144 00:07:00.370 --> 00:07:03.509 That's good news. That is very good news. And it 145 00:07:03.610 --> 00:07:09.000 completely negates half the horror movies of the 1950s. That 146 00:07:09.120 --> 00:07:10.339 would have to be a lot stubbier. 147 00:07:10.360 --> 00:07:13.199 They would have to be serious cankles to be able to. 148 00:07:13.259 --> 00:07:17.329 So as the ant gets bigger, the body weight... goes 149 00:07:17.970 --> 00:07:21.689 so much, grows faster than the strength of its spindly 150 00:07:21.850 --> 00:07:24.170 legs can support it. And it would just collapse under 151 00:07:24.209 --> 00:07:26.759 its own

weight. So you can't just scale up insects 152 00:07:27.240 --> 00:07:29.319 and get big insects. It's just not gonna happen. 153 00:07:29.339 --> 00:07:30.920 Well I'm gonna remove that as a fear I had. 154 00:07:31.980 --> 00:07:34.120 So the laws of physics prevent that. Which is why 155 00:07:34.139 --> 00:07:36.990 you can't have Godzilla as big as Godzilla is. 156 00:07:36.990 --> 00:07:38.670 How big could a person be? Like could you have 157 00:07:38.689 --> 00:07:39.949 a giant person that's the size. 158 00:07:39.790 --> 00:07:42.579 Of a building? No, no, no. I'm talking about any 159 00:07:42.600 --> 00:07:43.079 kind of life. 160 00:07:43.399 --> 00:07:44.110 Any kind of life. 161 00:07:44.139 --> 00:07:44.879 Right, right, right. 162 00:07:45.550 --> 00:07:48.930 So we don't need to fear giant elephants or King Kong. 163 00:07:49.009 --> 00:07:53.589 Plus, there's another thing that involves blood pressure. So if 164 00:07:53.610 --> 00:07:56.089 you're really, really big and you have to get blood 165 00:07:56.149 --> 00:07:58.379 to your brain, if your brain is at the top, 166 00:07:58.759 --> 00:08:01.560 you need a seriously pumping valve to do this. 167 00:08:01.579 --> 00:08:02.959 Well, if you had a heart, though, that was the 168 00:08:03.019 --> 00:08:06.180 size of a house inside your body that's the size 169 00:08:06.220 --> 00:08:09.089 of a... a skyscraper, would that be fine? 170 00:08:09.410 --> 00:08:11.670 I mean, that could pump with that kind of energy. Yeah, 171 00:08:11.730 --> 00:08:12.189 I guess so. 172 00:08:12.209 --> 00:08:15.750 You'd need maybe two or three hearts, is what we're saying, 173 00:08:15.769 --> 00:08:17.189 if you wanted to be the size of the Empire 174 00:08:17.209 --> 00:08:17.550 State Building. 175 00:08:17.569 --> 00:08:18.649 He's inventing the creature here. 176 00:08:19.529 --> 00:08:22.029 I'm just adding a heart to a giant thing that 177 00:08:22.050 --> 00:08:22.649 doesn't exist. 178 00:08:22.670 --> 00:08:23.560 I think that's fair. 179 00:08:23.769 --> 00:08:26.000 I think part of the problem is these things evolved 180 00:08:26.060 --> 00:08:28.600 from smaller versions, and so they have to kind of 181 00:08:28.720 --> 00:08:32.940 co-opt those miniature organs to something that works on the 182 00:08:32.980 --> 00:08:33.299 large scale. 183 00:08:33.320 --> 00:08:35.220 They didn't come out of the box big. Yeah, exactly. 184 00:08:35.399 --> 00:08:38.009 So the biggest... creature that ever existed is. 185 00:08:38.759 --> 00:08:42.620 No, it is the blue whale. that exist today. So 186 00:08:42.639 --> 00:08:45.840 what's fascinating to me is that mammals have some of 187 00:08:45.860 --> 00:08:49.820 the widest size range of any branch in the tree 188 00:08:49.840 --> 00:08:53.759 of life. What is the smallest mammal? It's like this big. 189 00:08:53.779 --> 00:08:57.570 There's a little... You could eat it. For sure. Like 190 00:08:57.730 --> 00:09:00.769 as an hors d'oeuvre, yeah. But you go from this 191 00:09:00.850 --> 00:09:02.970 to the blue whale. Now here's where the blue whale cheats. 192 00:09:03.250 --> 00:09:05.289 You look up blue whale in the book. Blue whale 193 00:09:05.330 --> 00:09:08.129 weighs four gazillion tons. Not really. 194 00:09:08.330 --> 00:09:09.529 Because gazillion isn't a number? 195 00:09:09.590 --> 00:09:10.029 Well, no, because. 196 00:09:12.720 --> 00:09:16.659 Not only for that reason, but it's actually floating in water. Right, 197 00:09:16.679 --> 00:09:20.120 it's cheating. It is not holding up that weight. And 198 00:09:20.159 --> 00:09:23.870 so once you are in water, then there is no 199 00:09:24.009 --> 00:09:27.549 limit to your mass. Wait, so could Godzilla exist but. 200 00:09:27.470 --> 00:09:28.009 Only in water? 201 00:09:28.049 --> 00:09:29.309 Godzilla loves being in the water. 202 00:09:29.610 --> 00:09:30.730 And he could then exist. 203 00:09:31.129 --> 00:09:32.610 But he couldn't come out of the water and start 204 00:09:32.649 --> 00:09:35.889 terrorizing the town. In the same way, a crocodile is 205 00:09:36.690 --> 00:09:40.360 basically useless on the ground. A Cardinal has to do 206 00:09:40.399 --> 00:09:43.240 a pushup just to walk and then go back down, 207 00:09:43.259 --> 00:09:45.539 because his legs are not directly under it, which is 208 00:09:45.580 --> 00:09:49.159 a big evolutionary advance. I don't need muscles to hold 209 00:09:49.250 --> 00:09:54.929 up my body weight, because vertically, I'm just supported. So 210 00:09:54.950 --> 00:09:57.330 to redo this, Godzilla can exist, but not out of 211 00:09:57.370 --> 00:09:59.000 the water. So it has to go into the water, 212 00:09:59.039 --> 00:10:02.159 that's right. And that's why huge clumsy things can be 213 00:10:02.220 --> 00:10:04.519 highly nimble swimming in the water. 214 00:10:04.539 --> 00:10:07.620 Like giant squids or jellyfish would just be a sack of. 215 00:10:08.169 --> 00:10:11.129 Yeah, yeah, exactly. Okay, great. All right. 216 00:10:11.529 --> 00:10:12.370 We learned a lot, thanks. 217 00:10:12.409 --> 00:10:16.629 And that was from whom? That was from Jordan Thompson. Thanks, Jordan. Yeah. 218 00:10:18.230 --> 00:10:18.730 Susan. 219 00:10:18.750 --> 00:10:22.090 Was that a Patreon question? No, it was Instagram. Okay. 220 00:10:22.389 --> 00:10:24.159 These are all sort of largely Facebook and Instagram. So 221 00:10:24.169 --> 00:10:24.669 this one's from Facebook. 222 00:10:24.700 --> 00:10:27.720 We're supposed to read Patreon questions first. Because they give 223 00:10:27.759 --> 00:10:29.899 us money and they bribe us to read their questions. 224 00:10:29.919 --> 00:10:32.259 First of all, I'm totally with you excluding the part 225 00:10:32.299 --> 00:10:34.080 where I have no questions from Patreon. 226 00:10:34.159 --> 00:10:34.899 Okay. 227 00:10:34.940 --> 00:10:36.379 So I can make them up. 228 00:10:36.799 --> 00:10:40.379 Okay. All right, go on. If

that's how you can 229 00:10:40.399 --> 00:10:40.759 bribe us. 230 00:10:41.039 --> 00:10:41.500 Yeah, yeah. 231 00:10:41.720 --> 00:10:43.559 No, I agree. 232 00:10:43.919 --> 00:10:48.950 Susan Minnob from Facebook asks... How sure are we about 233 00:10:49.129 --> 00:10:52.409 our map of our galaxy and the universe in general? 234 00:10:52.879 --> 00:10:57.100 Could our tools, techniques be mapping an illusion and that 235 00:10:57.139 --> 00:11:00.720 the universe is much smaller or larger than we've calculated? 236 00:11:02.399 --> 00:11:06.159 Your show is called Space Time. Yeah. Is everything we 237 00:11:06.179 --> 00:11:07.490 know based on lies? 238 00:11:08.029 --> 00:11:11.580 I mean, it's... It could just be that there's a 239 00:11:11.620 --> 00:11:14.519 giant dome that's painted kind of like the Wizard of 240 00:11:14.620 --> 00:11:15.120 Oz set. 241 00:11:15.139 --> 00:11:18.259 Right. Are we in a super complicated Truman Show? 242 00:11:19.460 --> 00:11:21.419 I think the closest thing to that is the idea 243 00:11:21.480 --> 00:11:26.000 of the holographic universe where you have this vastly distant 244 00:11:26.659 --> 00:11:29.289 shell that's a hologram and that our three dimensions are 245 00:11:29.309 --> 00:11:30.110 protected from two. 246 00:11:31.350 --> 00:11:32.950 Highly, highly hypothetical. 247 00:11:32.970 --> 00:11:35.950 I'm not even going to say theoretical. So, all right, 248 00:11:35.990 --> 00:11:40.779 how do we measure this stuff? With many scientists... working independently, 249 00:11:41.059 --> 00:11:44.730 making measurements independently and getting agreed upon results. In the 250 00:11:44.769 --> 00:11:47.269 case of the map of our universe, it's pointing multiple 251 00:11:47.289 --> 00:11:54.779 different telescopes at distant galaxies and basically calculating red shifts 252 00:11:54.860 --> 00:11:58.980 and also getting distances by different independent methods. 253 00:11:59.159 --> 00:12:02.250 So I would add that we use a regular telescope 254 00:12:02.269 --> 00:12:05.169 that is sensitive to visible light and that's the extension 255 00:12:05.190 --> 00:12:07.950 of our retina and we see a galaxy there. Now 256 00:12:08.009 --> 00:12:11.960 somebody else invents an infrared telescope or a microwave telescope 257 00:12:12.000 --> 00:12:14.220 or a radio telescope. and we scan the sky, we 258 00:12:14.259 --> 00:12:17.240 find the same object, but now emitting in these other bands. 259 00:12:17.700 --> 00:12:20.460 So this gives us confidence that the object is real, 260 00:12:21.019 --> 00:12:23.639 that it's actually there, and some interesting things are happening 261 00:12:23.679 --> 00:12:25.730 in it. And that it's not, and then, like, as 262 00:12:25.769 --> 00:12:28.769 you were saying, before I interrupted you, that you can 263 00:12:28.789 --> 00:12:31.970 get the distance to this object by multiple ways. They're 264 00:12:31.990 --> 00:12:34.960 not standard ways you would measure distances on Earth. On 265 00:12:34.980 --> 00:12:36.779 Earth you can pace out the distance, you could get 266 00:12:36.820 --> 00:12:40.740 a little tape measure, you can use now one of these... 267 00:12:42.799 --> 00:12:46.559 Like a wheel? Laser thingies. So there are multiple ways. 268 00:12:46.580 --> 00:12:48.340 If you get the same answer from all those ways, 269 00:12:48.559 --> 00:12:50.360 and all those ways are completely different from one another, 270 00:12:50.659 --> 00:12:52.940 you have confidence you have the right distance to the object. 271 00:12:53.259 --> 00:12:57.019 And so, yeah, you combine all of these factors, we 272 00:12:57.080 --> 00:13:01.159 think the universe is real, and it is what we 273 00:13:01.240 --> 00:13:04.019 measure it to be. But you can take a deeper 274 00:13:04.070 --> 00:13:10.789 philosophical point that there is no reality beyond the measurement. 275 00:13:11.970 --> 00:13:15.250 The measurement becomes the reality of the universe that we describe. 276 00:13:16.129 --> 00:13:19.509 So to say it really is this other thing, you're 277 00:13:19.549 --> 00:13:21.889 just not measuring it to be, so I'll say, how 278 00:13:21.950 --> 00:13:24.710 will you ever know that it's this other thing? 279 00:13:24.730 --> 00:13:26.809 Well, I don't know, the question wouldn't be that it's 280 00:13:26.850 --> 00:13:28.470 another thing, it's just that we are wrong. 281 00:13:29.450 --> 00:13:33.250 How would you know that we are? So we learn 282 00:13:33.289 --> 00:13:34.250 in quantum physics. 283 00:13:34.820 --> 00:13:37.720 You learn in quantum physics. 284 00:13:37.940 --> 00:13:45.320 The reality of the world only makes sense through the measurement. Right, 285 00:13:45.539 --> 00:13:47.419 in a sense, yeah. Yeah, in a sense. So you cannot, 286 00:13:47.759 --> 00:13:54.120 it doesn't mean anything to talk about a world that 287 00:13:54.179 --> 00:13:56.379 is outside of a measurement. 288 00:13:57.860 --> 00:14:00.159 That's what Niels Bohr would say. You have no access 289 00:14:00.299 --> 00:14:04.279 to it. I think others, for example, David Bohm and 290 00:14:05.039 --> 00:14:08.039 realists would argue otherwise. I think the important thing is 291 00:14:08.100 --> 00:14:11.580 not to confuse, though, the idea that we have a 292 00:14:11.639 --> 00:14:15.909 subjective experience of the universe, and that subjective experience isn't 293 00:14:15.970 --> 00:14:18.090 the universe. It's a different thing to the actual universe. 294 00:14:20.539 --> 00:14:24.460 But nonetheless, the universe remains consistent. Our subjective experience of 295 00:14:24.480 --> 00:14:27.759 the universe matches other people's subjective experience. We can all 296 00:14:27.799 --> 00:14:30.379 make measurements that agree with each other. And that gives 297 00:14:30.490 --> 00:14:32.950 us confidence that there is something objectively real out there, 298 00:14:33.029 --> 00:14:36.299 even if we can't say exactly

what it is. 299 00:14:36.539 --> 00:14:38.240 And I would add to that, but I'll tie a 300 00:14:38.279 --> 00:14:41.460 bow on it, that I look at something and I say, okay, 301 00:14:41.480 --> 00:14:43.840 that looks red to me. Well, am I on drugs 302 00:14:43.899 --> 00:14:47.289 or not? So that would be a subjective reality. So 303 00:14:47.330 --> 00:14:51.149 then you devise an experiment, an apparatus that measures wavelengths 304 00:14:51.210 --> 00:14:54.169 of light, and you've already calibrated it so that this 305 00:14:54.230 --> 00:14:56.009 wavelength is a red over here. So now you come 306 00:14:56.049 --> 00:14:58.379 to this and the machine measures red as well. 307 00:14:58.779 --> 00:14:59.659 Is the machine on drugs? 308 00:15:00.490 --> 00:15:03.009 You gotta teach the machine what red means first. We 309 00:15:03.029 --> 00:15:04.490 have to teach it over here what red is. And 310 00:15:04.509 --> 00:15:06.110 then we look at this thing that I'm looking at. 311 00:15:06.429 --> 00:15:10.049 And so now we both query the machine, what color 312 00:15:10.090 --> 00:15:12.309 is this? And the machine gives us the same answer. 313 00:15:12.649 --> 00:15:15.909 So I've removed my own brain from this experiment and 314 00:15:15.950 --> 00:15:19.169 I'm getting the same answer. So to a limit, our 315 00:15:19.250 --> 00:15:23.409 subjective experience is reality, but we know the limits of 316 00:15:23.470 --> 00:15:27.549 our subjective experience. And the whole point of science is 317 00:15:28.269 --> 00:15:34.929 to probe reality reducing our subjective interpretation by as much 318 00:15:35.190 --> 00:15:37.580 as is humanly possible, ideally to zero. 319 00:15:37.740 --> 00:15:40.980 Yeah, or refining the subjective model so that it better 320 00:15:41.019 --> 00:15:44.440 and better predicts the objective reality, even though it will 321 00:15:44.460 --> 00:15:49.779 never be the objective reality. It's a highly effective predictive apparatus. 322 00:15:49.940 --> 00:15:52.110 Okay. All right. 323 00:15:52.250 --> 00:15:52.669 Next question. 324 00:15:52.690 --> 00:15:53.990 I think we have time for one more question in 325 00:15:54.009 --> 00:15:55.179 this segment. All right, what do you got? 326 00:15:55.529 --> 00:16:01.580 From Leo Zusa on Instagram. How about the recent articles 327 00:16:01.700 --> 00:16:04.659 about the possibility of us being part of a simulation 328 00:16:04.700 --> 00:16:07.019 and the Big Bang being just the seeding event of 329 00:16:07.159 --> 00:16:08.090 such simulation? 330 00:16:08.259 --> 00:16:11.409 Thanks. I'm totally there. Yeah. I'm digging it every minute 331 00:16:11.429 --> 00:16:11.570 of it. 332 00:16:11.610 --> 00:16:12.769 You don't like it? 333 00:16:12.850 --> 00:16:14.490 I'm loving it. I want to hear your opinion. I'm 334 00:16:14.529 --> 00:16:16.850 loving it. I want to hear this. I'm loving it. 335 00:16:17.250 --> 00:16:18.389 So who made the simulation? 336 00:16:18.590 --> 00:16:23.600 Some snot-nosed kid in the parents' basement said, of an 337 00:16:23.759 --> 00:16:28.220 alien civilization who's bored and they're more advanced than we 338 00:16:28.360 --> 00:16:30.860 are and they have way more computing power than we are. 339 00:16:30.919 --> 00:16:31.259 Than we do. 340 00:16:31.299 --> 00:16:33.240 Right, so it's like a little handheld Nintendo you can do. 341 00:16:33.259 --> 00:16:38.049 Exactly, and so they program in enough detail to completely 342 00:16:38.110 --> 00:16:40.570 simulate every molecule in this universe and we are here 343 00:16:40.610 --> 00:16:43.830 for their entertainment. What else can you explain where things 344 00:16:43.889 --> 00:16:45.830 are going along just fine in the world, then all 345 00:16:45.850 --> 00:16:51.899 of a sudden, There's a complete disruption. The snot-nosed kid. Culturally, politically, economically, 346 00:16:52.139 --> 00:16:56.230 a complete disruption. I think they throw it in for entertainment. 347 00:16:56.419 --> 00:16:57.250 That's what I think. Okay. 348 00:16:57.710 --> 00:16:59.669 I'm going to say, I have two things to say. 349 00:17:01.389 --> 00:17:04.769 I predict that you don't believe that. That's my first prediction. 350 00:17:04.789 --> 00:17:06.890 But I don't want to put thoughts in your head. 351 00:17:06.910 --> 00:17:10.829 There's an argument for why that's more likely than any 352 00:17:10.869 --> 00:17:12.809 other scenario. I'll tell you that in a minute. The 353 00:17:12.910 --> 00:17:13.609 numbers game. 354 00:17:14.069 --> 00:17:17.369 So the idea that you need to produce one universe 355 00:17:17.450 --> 00:17:19.309 capable of producing universe simulations. 356 00:17:19.329 --> 00:17:19.990 And that's all you need. 357 00:17:20.049 --> 00:17:23.099 And if that universe produces billions of universe simulations, then 358 00:17:23.170 --> 00:17:25.440 any universe that you happen to find yourself in. 359 00:17:25.759 --> 00:17:28.660 It's more likely to be than the one universe that 360 00:17:28.700 --> 00:17:29.380 started it all. 361 00:17:29.740 --> 00:17:34.279 The way that virtual reality now exists and video games 362 00:17:34.319 --> 00:17:37.460 have advanced, it is likely that in, say, 1,000 years, whatever. 363 00:17:37.480 --> 00:17:39.180 Our virtual reality would be. 364 00:17:39.200 --> 00:17:41.200 Or 30 years. 30 years. 365 00:17:41.200 --> 00:17:42.160 1,000 or 30. 366 00:17:42.160 --> 00:17:45.299 Well, 30 years, whatever it was, would potentially be physical. 367 00:17:45.519 --> 00:17:47.160 You would be able to feel it. 368 00:17:47.660 --> 00:17:50.700 No, no, no, it doesn't even require that. It just 369 00:17:50.740 --> 00:17:54.789 requires that what you program in there, in your Nintendo, 370 00:17:55.130 --> 00:17:58.950 whatever it is, has enough complexity that in the mind 371 00:17:59.190 --> 00:18:02.230 of the characters in that game, they think they're real. 372 00:18:02.250 -->

00:18:03.549 And that's free will. 373 00:18:03.630 --> 00:18:05.670 It can't simulate the whole universe, because to simulate a 374 00:18:05.690 --> 00:18:08.109 universe perfectly, you need a computer the size of a universe. 375 00:18:08.190 --> 00:18:08.569 Do you? 376 00:18:08.990 --> 00:18:09.250 Do you? 377 00:18:09.430 --> 00:18:09.549 Yes. 378 00:18:11.089 --> 00:18:11.529 I don't know. 379 00:18:11.569 --> 00:18:15.750 Because, I mean, assuming it's a perfect. 380 00:18:16.089 --> 00:18:17.029 I do want to hear, but we've got to take 381 00:18:17.049 --> 00:18:17.230 a break. 382 00:18:17.809 --> 00:18:18.390 I want to hear it. 383 00:18:18.450 --> 00:18:20.349 I have so much to say. So much to say. 384 00:18:21.230 --> 00:18:23.569 When we come back, more of this Cosmic Queries edition 385 00:18:23.970 --> 00:18:30.630 on StarTalk. We're back on StarTalk. I'm Neil deGrasse Tyson. 386 00:18:30.750 --> 00:18:34.329 Eugene Merman. Hello. Back in the house. Eugene, you tweet 387 00:18:34.369 --> 00:18:34.950 by what handle? 388 00:18:35.569 --> 00:18:36.309 At Eugene Merman. 389 00:18:36.509 --> 00:18:39.160 At Eugene Merman. You got it. And I've got a 390 00:18:39.200 --> 00:18:44.650 friend and colleague, Matt O'Dowd, who is an associate up 391 00:18:44.690 --> 00:18:47.470 at the American Museum of Natural History, my day job. 392 00:18:48.049 --> 00:18:50.849 I serve as the director of the planetarium. But he's 393 00:18:51.089 --> 00:18:54.130 an affiliate of ours and a professor of his own 394 00:18:54.309 --> 00:18:58.160 up at Lehman College. That's right. So welcome. And you've 395 00:18:58.180 --> 00:19:00.339 got your own YouTube channel. I'm jealous. You've got a 396 00:19:00.359 --> 00:19:01.099 good YouTube channel. 397 00:19:01.359 --> 00:19:03.799 Well, my team's YouTube channel, I would say. 398 00:19:03.839 --> 00:19:06.759 Okay, that's good. PBS Digital Studios. PBS Digital Studios, very good. 399 00:19:07.519 --> 00:19:11.240 Titled Space Time. Exactly. We left off before the break, 400 00:19:12.410 --> 00:19:17.829 you asserting, to my disagreement, that you need a computer 401 00:19:17.849 --> 00:19:20.849 the size of the universe to program the universe. And 402 00:19:20.890 --> 00:19:24.089 I'm saying that the universe that's created doesn't have to 403 00:19:24.109 --> 00:19:26.920 be the whole universe. It can be just some other universe. 404 00:19:27.500 --> 00:19:30.819 It can be whatever less than the original universe needs 405 00:19:30.859 --> 00:19:32.680 to be to be whatever it is where they think 406 00:19:32.740 --> 00:19:35.059 it's their whole universe. That I agree with. Okay, good. 407 00:19:35.099 --> 00:19:37.380 That I agree with. We have no discussion. We agree. 408 00:19:38.160 --> 00:19:39.950 Let's go for a beer. All right. 409 00:19:40.589 --> 00:19:43.250 I do have one thing to say. So this whole 410 00:19:43.309 --> 00:19:46.009 idea recently came up. I think it got a bit 411 00:19:46.049 -->

00:19:48.630 of oomph because Elon Musk asserted that this was quite 412 00:19:48.690 --> 00:19:51.160 likely that we were part of this simulation. 413 00:19:51.279 --> 00:19:54.339 By the way, just to be clear. this thought did 414 00:19:54.380 --> 00:19:56.279 not originate with him. Oh, of course not. It goes 415 00:19:56.359 --> 00:19:59.559 back to the 90s, and there are a few philosophers 416 00:19:59.619 --> 00:20:04.329 who started, who set this ball rolling, and then many others, 417 00:20:04.650 --> 00:20:05.109 many others. 418 00:20:05.150 --> 00:20:07.730 And one of those writers whose name I'm blanking on. 419 00:20:07.730 --> 00:20:08.289 Pearl Jam? 420 00:20:08.890 --> 00:20:11.890 It might have been Pearl Jam. So the idea was 421 00:20:11.950 --> 00:20:14.440 that we are most likely in what he called. 422 00:20:14.460 --> 00:20:16.259 You've got to know your groups and when they peaked. 423 00:20:16.279 --> 00:20:19.640 This is kind of... This is good. This is good, Eugene. 424 00:20:19.660 --> 00:20:22.220 So the idea is an ancestor simulation. The idea that 425 00:20:22.420 --> 00:20:24.819 some future version of ourselves, when we're more advanced. 426 00:20:24.839 --> 00:20:28.329 Nick Bostrom is one of the original thinkers of this. Okay, 427 00:20:28.349 --> 00:20:29.250 but go on. 428 00:20:29.289 --> 00:20:31.849 The idea was that in the future, scientists or kids 429 00:20:31.869 --> 00:20:35.289 with Nintendo would choose to simulate the entire mental life 430 00:20:35.609 --> 00:20:39.730 of ancestors from hundreds of years ago, just as a 431 00:20:39.750 --> 00:20:42.150 study in past psychology. 432 00:20:42.960 --> 00:20:44.599 But that's all they have to do. 433 00:20:44.619 --> 00:20:47.839 They have to simulate only the activity of the mind and... 434 00:20:48.200 --> 00:20:51.069 input all of the sensors as long as they're consistent. Now, 435 00:20:51.430 --> 00:20:53.190 that probably we'll be able to do. I mean, the 436 00:20:53.210 --> 00:20:55.670 brain doesn't have that many connections that we can't, you know, 437 00:20:55.930 --> 00:20:58.490 in a couple of Moore's Law doublings sort that out. 438 00:21:00.130 --> 00:21:02.150 The problem with the... I recently heard that Moore's Law 439 00:21:02.210 --> 00:21:05.849 is now no longer 18 months. It's three years. I 440 00:21:05.950 --> 00:21:06.430 just heard that. 441 00:21:06.450 --> 00:21:09.309 Until we hit the next, I guess, iteration of once 442 00:21:09.329 --> 00:21:11.670 we move beyond silicon, maybe quantum computing. 443 00:21:11.690 --> 00:21:13.839 I'm just saying I heard that. Yeah, you might be right. 444 00:21:13.880 --> 00:21:17.190 By top people. I cannot tell you who. 445 00:21:17.230 --> 00:21:18.069 Very good people. 446 00:21:18.089 --> 00:21:21.930 Top people. Great. Okay, so where are you going with this? 447 00:21:22.289 --> 00:21:24.750 So the idea is it's not simulating a universe as 448 00:21:24.769 --> 00:21:28.049 you suggested. But I think it requires a lot of 449 00:21:28.069 --> 00:21:31.470 assumptions that future us will want to simulate the entire 450 00:21:31.519 --> 00:21:34.440 mental life of our ancestors and that we're more likely 451 00:21:34.460 --> 00:21:37.400 to be that. But my main objection is that part 452 00:21:37.440 --> 00:21:40.000 of the idea is that if something goes wrong, for example, 453 00:21:40.039 --> 00:21:41.900 we figure out we're part of the simulation, then. 454 00:21:43.650 --> 00:21:46.809 Whoever's running the simulation can edit it and remove that 455 00:21:46.930 --> 00:21:52.039 thought and business as usual. And so it's the most 456 00:21:52.119 --> 00:21:52.779 useless hypothesis. 457 00:21:52.799 --> 00:21:54.460 There are people who disappear and no one knows where 458 00:21:54.480 --> 00:21:54.740 they are. 459 00:21:55.299 --> 00:21:57.539 But that would be. 460 00:21:58.119 --> 00:22:03.779 We blame the Russians. You've had thoughts that popped into 461 00:22:03.799 --> 00:22:07.039 your head today that you never had previously in your life. 462 00:22:07.359 --> 00:22:09.769 So there's no way that the conspiracy can be proved 463 00:22:09.829 --> 00:22:15.660 or denied because everything's programmed. including evidence that we see 464 00:22:15.720 --> 00:22:19.769 that it is true, people disappearing, Roswell, all of this 465 00:22:19.789 --> 00:22:24.569 stuff is presumably programmed in. So I reject it because 466 00:22:24.609 --> 00:22:27.190 I think we need to continue on as though it's not. 467 00:22:28.059 --> 00:22:29.539 True. Well, you could do both. 468 00:22:29.779 --> 00:22:31.539 You could be like, well, maybe we're a simulation, but 469 00:22:31.559 --> 00:22:34.079 we should clearly live life as if we're people. 470 00:22:34.319 --> 00:22:35.440 Yes, we have free will. 471 00:22:35.619 --> 00:22:37.920 We would also still, like, even in a simulation, if 472 00:22:37.960 --> 00:22:40.160 you murdered someone, you'd go to simulation jail, which I'm 473 00:22:40.200 --> 00:22:40.880 sure is terrible. 474 00:22:40.900 --> 00:22:43.279 That's true. Yeah. I don't know. 475 00:22:43.299 --> 00:22:44.339 All right, next question. 476 00:22:44.359 --> 00:22:45.579 All right. 477 00:22:46.460 --> 00:22:53.240 BigDogD1223 asks, if Venus doesn't have a magnetic field, then 478 00:22:53.289 --> 00:22:56.190 how does it keep its thick atmosphere? Shouldn't it end 479 00:22:56.250 --> 00:22:56.990 up like Mars? 480 00:22:57.150 --> 00:22:57.269 Hmm. 481 00:22:58.069 --> 00:23:01.369 That's a good one. I'm not a planet guy, but 482 00:23:01.769 --> 00:23:04.109 let me sort of address it, first of all. So 483 00:23:04.529 --> 00:23:07.049 one of the things that keeps our magnetic field stoked 484 00:23:07.869 --> 00:23:12.089 is that down in our sort of semi-molten iron core, 485 00:23:12.690 --> 00:23:19.170 you get iron sort of moving, and Earth is spinning. 486 00:23:19.769 --> 00:23:22.549 And so since we

spin once a day, that's relatively fast, 487 00:23:25.240 --> 00:23:26.480 much faster than Venus. 488 00:23:27.359 --> 00:23:28.569 How fast does Venus spin? 489 00:23:29.089 --> 00:23:32.430 A little less often than once a year. And in 490 00:23:32.450 --> 00:23:35.250 the wrong direction. Right. What a dumb planet. You can 491 00:23:35.269 --> 00:23:39.450 have that as a book title. Yeah, what a dumb, 492 00:23:39.809 --> 00:23:43.740 so you are fewer you are fewer days old on 493 00:23:43.779 --> 00:23:48.400 Venus than you are years. So it's not churning, you 494 00:23:48.440 --> 00:23:50.759 don't get this sort of what they call differential rotation. 495 00:23:52.000 --> 00:23:54.460 So Venus, right, does not have a significant magnetic field. 496 00:23:54.480 --> 00:23:58.880 The magnetic field protects you from the ablative effects of 497 00:23:58.900 --> 00:24:03.119 the solar wind. And so there's Venus closer to the sun, 498 00:24:04.059 --> 00:24:08.960 getting twice the flux of solar wind than we get. 499 00:24:10.740 --> 00:24:15.269 It maintains its atmosphere. So generally, what goes on here 500 00:24:15.329 --> 00:24:17.650 on Earth is, it's not that it will blow away 501 00:24:17.690 --> 00:24:23.390 our atmosphere. It's that if there's a water molecule high up, H2O, 502 00:24:24.369 --> 00:24:27.069 the energy from the sun can break apart that water molecule, 503 00:24:27.130 --> 00:24:29.339 separate the hydrogen from it, then you lose the hydrogen. 504 00:24:29.359 --> 00:24:32.759 Because hydrogen is very light. And in a given temperature gas, 505 00:24:32.859 --> 00:24:36.779 it's the fastest moving atom. If it doesn't bind onto something, 506 00:24:36.859 --> 00:24:39.349 it's just gonna escape. You're gonna lose your hydrogen in 507 00:24:39.390 --> 00:24:44.470 a Earth-sized gravity. So you can systematically lose your water 508 00:24:45.269 --> 00:24:47.740 from such a place. And Venus, as far as we know, 509 00:24:47.779 --> 00:24:51.500 has no water. It's all carbon dioxide. Mostly carbon dioxide atmosphere. 510 00:24:51.519 --> 00:24:54.059 It has hydrochloric acid up there, which I guess has 511 00:24:54.220 --> 00:24:57.359 some hydrogen. But I think part of it is also 512 00:24:57.420 --> 00:25:00.019 that Mars is much, much lighter than Venus. And so 513 00:25:00.059 --> 00:25:04.369 Venus is almost as massive as the Earth. It holds 514 00:25:04.450 --> 00:25:09.109 on to its atmosphere. And it has so much of it. 515 00:25:09.190 --> 00:25:11.089 It's got to be losing stuff, but the time scale 516 00:25:11.109 --> 00:25:12.250 is just much, much longer. 517 00:25:12.390 --> 00:25:15.789 And it's got nearly 100 times the atmospheric pressure as Earth, so. 518 00:25:16.529 --> 00:25:17.670 from, how does that? 519 00:25:18.279 --> 00:25:22.049 Well, so if you go there, you would, you'd be 520 00:25:22.170 --> 00:25:25.480 crushed split seconds before you vaporized. 521 00:25:26.180 --> 00:25:28.630 Is that the order? 522 00:25:29.309 --> 00:25:32.130 I don't know the full origin of that. It's got 523 00:25:32.150 --> 00:25:36.390 a lot more of it. Well, I'm not going there. 524 00:25:36.529 --> 00:25:37.990 What's the record? 525 00:25:38.690 --> 00:25:41.930 The record for a lander on Venus is something like two, 526 00:25:41.950 --> 00:25:45.210 three hours before it crumpled in like a big fan. 527 00:25:45.490 --> 00:25:48.619 And the big Venus people were the Russians. They had 528 00:25:48.640 --> 00:25:49.740 the Venera spacecraft. 529 00:25:50.400 --> 00:25:51.920 And they sent it and they got some info and 530 00:25:51.940 --> 00:25:52.460 then got crushed. 531 00:25:52.519 --> 00:25:55.319 Yeah, you get crushed and it melts. They knew this, 532 00:25:55.440 --> 00:25:57.940 but it's still a challenge. While we were going to Mars, 533 00:25:57.980 --> 00:25:58.789 they were going to Venus. 534 00:25:58.900 --> 00:26:01.410 Right. Did we go to Mars because it's super easy? 535 00:26:01.950 --> 00:26:05.390 It's actually hard. Mars is hard. Venus is close enough. 536 00:26:05.410 --> 00:26:08.730 But a quick thing. So while we're on the subject, 537 00:26:10.089 --> 00:26:13.890 allow me to tell you the story of Venus. 538 00:26:14.450 --> 00:26:14.930 Sure. 539 00:26:15.519 --> 00:26:15.700 Okay. 540 00:26:15.720 --> 00:26:16.839 I was going to say, do you know the story 541 00:26:16.880 --> 00:26:17.240 of Venus? 542 00:26:17.299 --> 00:26:18.039 I know the story of Venus. 543 00:26:18.220 --> 00:26:18.440 Great. 544 00:26:18.619 --> 00:26:24.140 So... If you're from Mars, you're a Martian. If you're 545 00:26:25.079 --> 00:26:28.079 from Earth, you're an Earthling. If you're from Venus, you're 546 00:26:28.099 --> 00:26:30.299 a Venusian. We have these words if you are of 547 00:26:30.400 --> 00:26:34.160 those places. It turns out Martian is correct, Earthling is good. 548 00:26:35.400 --> 00:26:42.049 But Venusian, that's a improperly formed word. We're stuck with 549 00:26:42.109 --> 00:26:46.250 that word because the properly formed word was already taken 550 00:26:46.789 --> 00:26:50.349 by a whole other branch of science. The medical doctors. 551 00:26:52.180 --> 00:26:56.990 If you are of Venus, you are venereal. Oh, from 552 00:26:57.019 --> 00:26:59.539 the Latin. From the Latin, exactly. That is the genitive 553 00:26:59.579 --> 00:27:04.279 form of Venus. And so, when doctors found diseases peculiar 554 00:27:04.319 --> 00:27:08.539 to lovemaking, and Venus being the goddess of love and beauty, 555 00:27:08.869 --> 00:27:11.849 they said, let's name it all after Venus. So that 556 00:27:11.930 --> 00:27:14.869 became the category of venereal beauty. And aliens were like, 557 00:27:14.890 --> 00:27:17.269 we would rather you didn't call us venereal. Right, exactly. 558 00:27:17.289 --> 00:27:20.650 They are pissed off ever since. So we should not 559 00:27:20.690 --> 00:27:24.240 be surprised that the spacecraft The Russians sent to

Venus 560 00:27:24.279 --> 00:27:27.119 were all called the Venera series, and it's because of 561 00:27:27.140 --> 00:27:27.980 that genitive form. 562 00:27:28.299 --> 00:27:32.880 So war wounds should be Martian-like. That's a Martian cortusion 563 00:27:32.940 --> 00:27:33.500 you receive. 564 00:27:33.519 --> 00:27:37.730 Yeah, if you want to be symmetric about that, consistent. 565 00:27:38.430 --> 00:27:41.089 You have a Martian wound. Yeah, yeah, very bad wound. 566 00:27:41.109 --> 00:27:44.099 Let's try to make that happen. Yeah, right. Nielsen.... 567 00:27:51.759 --> 00:27:53.539 From Syracuse in upstate New York. 568 00:27:53.559 --> 00:27:55.559 You're almost as bad as Chuck Nice at this. He 569 00:27:55.920 --> 00:27:57.859 mangles the names every single time. 570 00:27:57.940 --> 00:27:59.240 I'm not mangling anything. 571 00:27:59.259 --> 00:28:00.460 People choose weird names. 572 00:28:00.819 --> 00:28:04.200 Yeah, meaning people's monikers, which isn't a word. 573 00:28:04.220 --> 00:28:08.109 I had a space-time commenter called Sss. 574 00:28:08.130 --> 00:28:09.750 I think I pronounced it correctly. Yeah. 575 00:28:10.509 --> 00:28:14.380 Spelled S space S-S. And we have an obligation. 576 00:28:14.400 --> 00:28:18.559 I feel like I read Big Dog D-1223 quite accurately. 577 00:28:18.619 --> 00:28:21.160 You did justice to Big Dog D-12223. All right. 578 00:28:21.259 --> 00:28:26.809 So Nielsen, also accurate, from Syracuse asks, do scientists and 579 00:28:26.849 --> 00:28:29.910 theorists have any idea how much time passed before the 580 00:28:29.950 --> 00:28:32.990 Big Bang? Was there time before the Big Bang? 581 00:28:33.650 --> 00:28:35.730 I can answer that. Yeah, I know. We have no 582 00:28:35.890 --> 00:28:38.589 freaking idea. Okay, next question. No, what do you have? 583 00:28:38.609 --> 00:28:39.170 What do you got for that? 584 00:28:39.579 --> 00:28:42.440 I mean, the standard wisdom was always that time started 585 00:28:42.829 --> 00:28:45.410 at the Big Bang. And before that, there was no time. 586 00:28:45.430 --> 00:28:48.390 That was the first second happened then. But, you know, 587 00:28:48.410 --> 00:28:50.930 I think there's new thinking now. I think ideas like 588 00:28:52.299 --> 00:28:55.539 eternal inflation. So the idea that possibly this universe just 589 00:28:56.059 --> 00:29:01.289 nucleated out of some inflating, rapidly expanding multiverse type thing 590 00:29:01.609 --> 00:29:03.410 in which time might have some sort of existence. 591 00:29:03.849 --> 00:29:05.569 Yeah, but then it would be time, there'd be a 592 00:29:05.670 --> 00:29:10.380 meta time for the meta universe, basically. Whereas our bubble 593 00:29:10.960 --> 00:29:14.079 surely has a beginning point. Sure, that one dimension. So 594 00:29:14.099 --> 00:29:16.859 I don't want to get semantic on it, we can say, Time, 595 00:29:16.980 --> 00:29:20.000 as we measure it, began at our beginning. But if 596 00:29:20.019 --> 00:29:22.859 we are part of this multiverse, then you should think 597 00:29:22.900 --> 00:29:26.869 of a multi-time that actually is the master clock of all. 598 00:29:26.940 --> 00:29:30.250 Yeah, or it's talking instead of chain of cause and effect. 599 00:29:30.309 --> 00:29:33.390 There was a cause before the Big Bang of some sort. 600 00:29:34.309 --> 00:29:35.750 So like roughly an hour? 601 00:29:36.519 --> 00:29:38.160 Yes, like, you know. 602 00:29:38.160 --> 00:29:38.420 45 minutes? 603 00:29:38.420 --> 00:29:38.960 45 minutes. 604 00:29:39.019 --> 00:29:40.940 I don't want to be inaccurate. All right. 605 00:29:41.119 --> 00:29:41.460 Mr. 606 00:29:41.619 --> 00:29:45.660 Findle asks, we created tools to detect and see different 607 00:29:45.720 --> 00:29:48.809 wavelengths of light that our eyes can't see. 608 00:29:48.849 --> 00:29:49.789 That's for damn sure. 609 00:29:49.809 --> 00:29:52.410 Are there any ideas of tools that would allow us 610 00:29:52.490 --> 00:29:55.250 to detect and see dark matter? 611 00:29:56.069 --> 00:29:58.910 So many ideas, depending on what. 612 00:29:59.470 --> 00:30:04.359 Well, first, we do see the effects dark matter has 613 00:30:04.480 --> 00:30:09.000 on matter. Dark matter has gravity. It has gravity. That's 614 00:30:09.039 --> 00:30:10.799 how we know it's there. That's why we talk about 615 00:30:10.940 --> 00:30:13.099 it at all. And I keep saying this, it shouldn't 616 00:30:13.180 --> 00:30:15.220 ever have been named dark matter. It should have just 617 00:30:15.240 --> 00:30:18.539 been called Fred. Because we don't know anything about it. 618 00:30:19.089 --> 00:30:20.890 Meaning it's not matter per se. 619 00:30:21.349 --> 00:30:23.369 It may be matter, maybe not. So to call it 620 00:30:23.470 --> 00:30:25.369 any kind of matter is misleading. 621 00:30:25.650 --> 00:30:25.829 Right. 622 00:30:25.869 --> 00:30:29.519 It's presumptive. Presumptive. That's a better word. Thank you. But 623 00:30:30.440 --> 00:30:36.230 what it actually is is dark gravity. That is literally true. Yeah. So... 624 00:30:36.819 --> 00:30:41.210 So we see its effects on things. And that's pretty good. 625 00:30:42.130 --> 00:30:44.410 So that's why we all know something's happening out there. 626 00:30:44.430 --> 00:30:47.640 All right. So now, is there some other way we 627 00:30:47.680 --> 00:30:48.980 can detect it? Do you have any ideas? 628 00:30:49.000 --> 00:30:50.720 It depends on what it is. I mean, if it 629 00:30:50.759 --> 00:30:54.250 is really massive and some kind of particle, then... People 630 00:30:54.269 --> 00:30:55.109 are all over it. 631 00:30:55.650 --> 00:30:58.250 The over-under on that is that it's going to be 632 00:30:58.269 --> 00:30:59.269 a particle. 633 00:30:59.390 --> 00:31:02.650 Like some ideas is that it might self-annihilate when dark 634 00:31:02.670 --> 00:31:05.880 matter particles find each other and that would produce very 635 00:31:05.920 --> 00:31:09.539 high

energy light or other particles that we could detect 636 00:31:09.579 --> 00:31:13.079 here on Earth as little flashes of gamma rays or 637 00:31:13.099 --> 00:31:13.660 cosmic rays. 638 00:31:13.680 --> 00:31:16.700 Is dark matter something that's far out in space or 639 00:31:16.819 --> 00:31:19.950 is it near the Earth or is it everywhere? Meaning 640 00:31:19.970 --> 00:31:20.769 it might be in this room? 641 00:31:21.049 --> 00:31:24.380 It's certainly in this room, but Dark matter is so diffuse, 642 00:31:25.279 --> 00:31:28.500 it's manifest only on very large scales. So it is 643 00:31:28.680 --> 00:31:33.180 so dominated by ordinary matter in normal situations, you can 644 00:31:33.329 --> 00:31:35.509 live life as though it's not there. Same with our 645 00:31:35.549 --> 00:31:38.930 solar system. You don't need to invoke dark matter to 646 00:31:38.990 --> 00:31:41.400 calculate anything that's going on anywhere around us. 647 00:31:41.430 --> 00:31:43.910 But in deeper space where there's less, it has. 648 00:31:43.950 --> 00:31:44.569 In bigger space. 649 00:31:44.609 --> 00:31:46.990 There's more space, and so it just adds up over 650 00:31:47.109 --> 00:31:47.880 the light years. 651 00:31:48.170 --> 00:31:51.140 And here's the thing. If it is a particle, might 652 00:31:51.160 --> 00:31:53.660 we ever find a dark matter planet? or dark matter 653 00:31:54.119 --> 00:31:58.180 something else? Probably not, because not only does this dark 654 00:31:58.240 --> 00:32:02.539 matter stuff, Fred, not interact with us, ordinary matter, it 655 00:32:02.559 --> 00:32:05.309 doesn't even interact with itself. If you don't interact with yourself, 656 00:32:05.609 --> 00:32:07.670 you cannot coalesce and become something. 657 00:32:07.690 --> 00:32:09.750 How do we know it doesn't interact with itself? 658 00:32:09.829 --> 00:32:11.750 Because it would otherwise stick to itself. 659 00:32:11.910 --> 00:32:16.450 There are ideas that would allow it to hang out 660 00:32:16.490 --> 00:32:20.319 near each other? I mean, to annihilate itself when they interact, 661 00:32:20.359 --> 00:32:22.839 but it's so small and spread out that it just 662 00:32:22.880 --> 00:32:23.849 doesn't happen very often. 663 00:32:24.109 --> 00:32:26.150 You think it's only a frequency issue? 664 00:32:27.089 --> 00:32:30.059 By some models, or it might not interact with itself. 665 00:32:30.230 --> 00:32:35.460 That's also possible. Right, because our particles, we make molecular bonds, 666 00:32:35.519 --> 00:32:38.799 atomic bonds. So we make molecules, and then we can 667 00:32:38.819 --> 00:32:41.799 be this fleshy thing called humans. It's not capable of 668 00:32:41.839 --> 00:32:44.220 that sort of complexity. But it'd be really cool if 669 00:32:44.240 --> 00:32:48.890 they were like humanoid dark matter entities. That would be cool. 670 00:32:48.950 --> 00:32:51.089 They'd be completely transparent because they don't interact with light. 671 00:32:51.450 -->

00:32:53.789 They could be right here, right now. They could be 672 00:32:53.809 --> 00:32:56.230 all around us. Oh, maybe that's what angels are. Okay. 673 00:32:57.269 --> 00:32:59.519 Solve that. Yep. One more real quick. What do you 674 00:32:59.619 --> 00:33:00.339 got before we break? 675 00:33:00.390 --> 00:33:06.569 Someone let Mike Huckabee know. Justin Kenna on Instagram asks, 676 00:33:07.529 --> 00:33:09.519 is it possible for the fabric of space to be 677 00:33:09.599 --> 00:33:13.420 ripped or pulled apart? Could an overexpanded black hole then 678 00:33:13.460 --> 00:33:15.900 be the cause of a sort of big bang as 679 00:33:15.940 --> 00:33:18.529 the matter rips a hole through the fabric of space? 680 00:33:18.789 --> 00:33:24.069 I saw that episode of Doctor Who. So I love 681 00:33:24.109 --> 00:33:27.809 the idea that we might rip. It's terrifying and beautiful 682 00:33:27.849 --> 00:33:29.670 at the same time. We're not gonna rip in what 683 00:33:29.690 --> 00:33:34.500 we're doing now, but in the distant future where this 684 00:33:34.680 --> 00:33:40.339 dark energy pressure of the vacuum is forcing an acceleration. 685 00:33:40.460 --> 00:33:46.880 An acceleration of the expansion. That will grow exponentially. So 686 00:33:47.220 --> 00:33:50.549 I'm curious, might there be a day where space is 687 00:33:50.609 --> 00:33:57.890 expanding so rapidly that its pliability cannot keep up with 688 00:33:57.930 --> 00:34:00.170 what's happening to it and it just rips instead of 689 00:34:00.210 --> 00:34:01.170 continues to stretch? 690 00:34:01.430 --> 00:34:04.490 Or at the very least, atomic nuclei ripped apart and. 691 00:34:05.990 --> 00:34:09.900 Yeah. So my, if that's your favorite cosmic destruction. It 692 00:34:09.940 --> 00:34:12.800 would be terrifying, but oh my gosh, that'd be a 693 00:34:12.860 --> 00:34:15.679 new thing. I think even cooler is vacuum decay. 694 00:34:16.599 --> 00:34:16.719 Oh. 695 00:34:16.940 --> 00:34:20.530 So the idea. Vacuum decay. Do you want, oh. 696 00:34:20.610 --> 00:34:21.650 What's vacuum decay? 697 00:34:21.670 --> 00:34:24.309 Vacuum decay is great. Over the commercial. I'll decide if 698 00:34:24.369 --> 00:34:27.090 it's great. It could happen anytime. Over the commercial, he'll 699 00:34:27.130 --> 00:34:31.340 tell you. Okay. When we come back, more of Star Talks, 700 00:34:31.760 --> 00:34:38.960 Cosmic Queries, Pupiri Editions. Neil deGrasse Tyson back at you. 701 00:34:39.059 --> 00:34:45.710 Star Talk. Cosmic Queries Edition. Potpourri. Grab bag. I got 702 00:34:45.789 --> 00:34:47.559 Eugene Merman. Eugene. Hello. 703 00:34:48.059 --> 00:34:48.510 Love having you. 704 00:34:48.559 --> 00:34:51.360 Love being here. Don't stay away for so long next time. 705 00:34:51.500 --> 00:34:52.179 I'll be back soon. 706 00:34:52.260 --> 00:34:55.139 Yeah, call me or something. I will. Okay. Matt, great 707 00:34:55.159 --> 00:34:57.820 to have you. Hey, guys. We're at the YouTube studios. Why? 708 00:34:57.840 --> 00:35:00.590 Because you have a YouTube show. Sure, I do. It's 709 00:35:00.619 --> 00:35:03.110 called Space Time. Great name. Thank you very much. 710 00:35:03.130 --> 00:35:03.510 And it's a PBS. 711 00:35:03.530 --> 00:35:03.989 Good name. 712 00:35:04.050 --> 00:35:07.170 I didn't come up with it, but yeah. PBS Digital Studios. 713 00:35:07.190 --> 00:35:09.610 That's right. Very good. And so we're doing Q & 714 00:35:09.489 --> 00:35:14.480 A here, and... Something that keeps me awake at night 715 00:35:14.679 --> 00:35:18.920 is wondering whether the vacuum energy of the universe is stable. 716 00:35:20.179 --> 00:35:22.219 Have you thought about that? I have lost sleep. You've 717 00:35:22.239 --> 00:35:24.199 lost sleep too? Last night I lost some sleep. Have you? 718 00:35:24.469 --> 00:35:25.150 I'm about to. 719 00:35:25.170 --> 00:35:26.969 We're going to make sure you join the class. 720 00:35:26.989 --> 00:35:27.409 Yeah, yeah. 721 00:35:27.710 --> 00:35:28.159 What is it? 722 00:35:28.610 --> 00:35:30.869 So vacuum decay. 723 00:35:31.150 --> 00:35:31.309 Yes. 724 00:35:32.260 --> 00:35:34.989 It's scarier than the big rip that might happen due 725 00:35:35.030 --> 00:35:37.710 to dark energy because it could happen at any time. 726 00:35:38.070 --> 00:35:41.489 It could happen spontaneously. So the idea is that the vacuum, 727 00:35:42.650 --> 00:35:45.880 basically a vacuum means there's nothing in it. But actually 728 00:35:45.889 --> 00:35:48.539 the vacuum has some tiny bit of energy. The fields 729 00:35:48.639 --> 00:35:50.960 that permeate the universe that give rise to particles are 730 00:35:51.300 --> 00:35:53.760 through the vacuum. Now, one of those fields is the 731 00:35:53.860 --> 00:35:59.050 Higgs field. It's what gives subatomic particles mass. The famous 732 00:35:59.070 --> 00:35:59.849 Higgs boson. 733 00:36:00.429 --> 00:36:03.170 It's a badass particle. If you had to be a particle. 734 00:36:03.369 --> 00:36:04.030 That's the one you'd be. 735 00:36:04.050 --> 00:36:04.630 That's the one you'd be. 736 00:36:04.630 --> 00:36:05.250 The God particle. 737 00:36:05.269 --> 00:36:06.050 The God particle. 738 00:36:06.130 --> 00:36:07.309 We've got a good nickname. 739 00:36:07.349 --> 00:36:09.590 We've got the best nickname. So the idea is that 740 00:36:10.150 --> 00:36:11.750 that Higgs field. Can I give a quick explanation for 741 00:36:11.789 --> 00:36:16.110 how it gives mass? Sure. I think this explanation works. Okay. 742 00:36:16.170 --> 00:36:20.230 Think of a party in Los Angeles. Okay. In Hollywood. 743 00:36:20.269 --> 00:36:22.210 I've never been invited to one, but. Okay, all right. 744 00:36:22.889 --> 00:36:28.139 And so what the Higgs field does is it will 745 00:36:29.019 --> 00:36:34.260 create a resistance to your ability to move through that field, 746 00:36:35.260 --> 00:36:37.800 depending on what kind of particle you are. And the 747 00:36:37.900 -->

00:36:40.920 greater is that resistance, the more you measure its mass 748 00:36:40.960 --> 00:36:44.690 to be, okay? Because massive things don't move quickly. So 749 00:36:44.710 --> 00:36:47.369 you go to a party in Los Angeles, and somebody 750 00:36:47.469 --> 00:36:51.670 nobody has heard of walks in, okay? Arnold Schmednick, okay? Fine, 751 00:36:51.710 --> 00:36:53.980 walks in. No one crowds around him. He can go 752 00:36:54.079 --> 00:36:58.639 straight to the bar. He has very low party mass. 753 00:37:00.000 --> 00:37:04.780 Beyonce walks in. Then a scrum builds around her. She 754 00:37:04.940 --> 00:37:08.760 cannot move because people are taking selfies, getting autographs, asking 755 00:37:08.780 --> 00:37:14.449 her questions, paparazzi. She moves five inches a minute. Takes 756 00:37:14.469 --> 00:37:16.489 her a half hour to get across the thing. She 757 00:37:16.530 --> 00:37:20.210 has very high party mass. The party field granted her 758 00:37:20.269 --> 00:37:21.690 more mass than Arnold Schmegman. 759 00:37:22.269 --> 00:37:25.480 So Arnold is a neutrino and Beyonce is a. 760 00:37:25.590 --> 00:37:28.800 It's a massive particle. towel electron. Exactly. Yeah. Okay. Good. 761 00:37:29.219 --> 00:37:31.380 So the universe is... I get your approval on that analogy. 762 00:37:31.619 --> 00:37:33.440 I think it's good. I think it's a great start. 763 00:37:33.599 --> 00:37:35.590 And I direct everyone to an episode on space time. 764 00:37:35.610 --> 00:37:38.329 We've done this subject that takes it only a tiny 765 00:37:38.349 --> 00:37:38.869 little bit further. 766 00:37:39.070 --> 00:37:41.210 Just Okay, all right, good, good. 767 00:37:41.710 --> 00:37:43.530 But the cool thing about. 768 00:37:43.369 --> 00:37:44.889 The Higgs field. I think you just dissed my example. No, 769 00:37:45.130 --> 00:37:47.630 I love this. Well, here's what I want to know. 770 00:37:47.690 --> 00:37:49.570 I've never been invited to that party, and I know 771 00:37:49.610 --> 00:37:50.909 that I passed through. 772 00:37:50.969 --> 00:37:53.170 I know. Tell me about the vacuum that I need 773 00:37:53.190 --> 00:37:54.769 to be afraid of. Okay. 774 00:37:54.929 --> 00:37:55.289 Please. 775 00:37:56.010 --> 00:37:59.860 So the Higgs field works because it has a non-zero 776 00:37:59.909 --> 00:38:02.320 energy everywhere. There's a little bit of Higgs-iness everywhere in 777 00:38:02.340 --> 00:38:02.880 the universe. 778 00:38:02.940 --> 00:38:03.139 Yeah. 779 00:38:03.219 --> 00:38:05.619 This little field that goes, you know, through a volume 780 00:38:05.679 --> 00:38:05.940 of space. 781 00:38:05.960 --> 00:38:06.739 That's how I describe it. 782 00:38:06.739 --> 00:38:10.469 Right, yeah. And just to be clear. because in case 783 00:38:10.570 --> 00:38:13.230 anyone who's watching this is really young, and the only 784 00:38:13.269 --> 00:38:15.289 concept of a vacuum is a machine that's sitting in 785 00:38:15.309 --> 00:38:19.909 the

closet. So that machine creates a vacuum, hence we 786 00:38:19.929 --> 00:38:25.340 call them vacuums. So in space, unlike, who was it 787 00:38:25.409 --> 00:38:29.539 that said it? Nature abhors a vacuum, only on the 788 00:38:29.579 --> 00:38:32.989 surface of the Earth. the universe is vacuum, so the 789 00:38:33.010 --> 00:38:35.530 universe loves itself some vacuum. Okay, so. 790 00:38:35.849 --> 00:38:38.280 It's a region where there's nothing, except there isn't nothing, 791 00:38:38.320 --> 00:38:40.119 there's some little Higgs energy. 792 00:38:40.199 --> 00:38:40.800 Exactly, go on. 793 00:38:40.840 --> 00:38:44.889 Right, and so when the universe was settling down, soon 794 00:38:44.929 --> 00:38:48.329 after the Big Bang, that Higgs energy found a nice 795 00:38:48.409 --> 00:38:53.130 comfortable place to be, a value to take and you 796 00:38:53.150 --> 00:38:55.670 can sort of think of it as it was falling 797 00:38:55.750 --> 00:38:57.769 downhill in energy and it found a nice dip in 798 00:38:57.809 --> 00:38:59.570 the energy that it could be and came to rest 799 00:38:59.630 --> 00:39:05.110 at that particular energy. But over that little hump, there 800 00:39:05.170 --> 00:39:09.340 may be a deeper drop and a much more preferential, comfortable, 801 00:39:09.980 --> 00:39:12.460 lower energy for the Higgs field to take. The vacuum 802 00:39:13.250 --> 00:39:15.960 If it could get to that lower energy point, it 803 00:39:16.000 --> 00:39:18.719 would go there because the universe, one thing the universe 804 00:39:18.880 --> 00:39:20.800 does love to do is be in a low energy state. 805 00:39:21.280 --> 00:39:23.860 That's something it will do whenever it can. But it 806 00:39:24.260 --> 00:39:26.809 needs to realize that over that little hump, that low 807 00:39:26.829 --> 00:39:29.969 energy state is there. It only takes one little pass 808 00:39:30.099 --> 00:39:33.420 of the universe to get the message that it can 809 00:39:33.480 --> 00:39:34.320 have a lower Higgs state. 810 00:39:34.340 --> 00:39:36.820 And it takes the whole rest of the universe with it. Yeah. 811 00:39:36.929 --> 00:39:39.429 And so the idea is you have this vacuum decay, 812 00:39:39.469 --> 00:39:41.170 that little part of the vacuum decays to that lower 813 00:39:41.210 --> 00:39:43.690 energy state. And all of physics goes out the window. 814 00:39:43.750 --> 00:39:47.400 Everything loses mass. All particles are can suddenly move at 815 00:39:47.420 --> 00:39:51.030 the speed of light. Time winks out as we understand it. 816 00:39:51.070 --> 00:39:52.289 We will become essentially photons. 817 00:39:52.389 --> 00:39:56.030 Maybe say dogs and cats start dating one another. 818 00:39:56.090 --> 00:39:57.949 If they don't turn into bubbles first. 819 00:39:57.969 --> 00:40:00.710 That is highly hypothetical. No one has proven that. 820 00:40:00.730 --> 00:40:01.369 Wait, so say it again. 821 00:40:01.449 --> 00:40:05.139 What happens? Let me try now.

Can I try now? Yeah. 822 00:40:05.239 --> 00:40:06.789 I was going to do the expanding bubble, but go. Okay, no, 823 00:40:06.800 --> 00:40:07.460 do the expanding bubble. 824 00:40:07.760 --> 00:40:10.679 So once the universe realizes that it is this new 825 00:40:10.800 --> 00:40:13.460 energy state and not what we thought, that bubble expands 826 00:40:13.639 --> 00:40:16.429 and at the speed of light envelops the universe. 827 00:40:17.010 --> 00:40:18.550 Okay. But, you know, the universe is big, so it 828 00:40:18.590 --> 00:40:19.030 might take a while. 829 00:40:19.050 --> 00:40:21.030 So it depends where it starts. So maybe it's already 830 00:40:21.159 --> 00:40:21.840 started somewhere. 831 00:40:21.860 --> 00:40:23.679 Oh, so it only moves at the speed of light 832 00:40:23.719 --> 00:40:25.960 when this happens. Yes. Unless it tunnels there, then the 833 00:40:25.980 --> 00:40:29.849 whole thing happens instantaneously. I don't know. Because it's already 834 00:40:30.150 --> 00:40:32.210 happening somewhere. Tunneling is instantaneous. 835 00:40:33.190 --> 00:40:36.809 But the distance is limited. Tunneling distance is a function 836 00:40:36.829 --> 00:40:37.340 of probability. 837 00:40:37.550 --> 00:40:38.050 Okay. 838 00:40:38.159 --> 00:40:40.079 But if this is happening somewhere in the universe, then 839 00:40:40.099 --> 00:40:41.170 we'll just get swallowed up in it? 840 00:40:41.599 --> 00:40:42.280 Yeah, basically. 841 00:40:42.980 --> 00:40:44.260 What are the chances it's already happening? 842 00:40:45.530 --> 00:40:47.969 The chance is, we have no idea. 843 00:40:48.130 --> 00:40:49.829 By the way, I think of this loss of the 844 00:40:49.869 --> 00:40:52.789 vacuum state every time I fly over Crater Lake. You know, 845 00:40:53.050 --> 00:40:55.840 it's the volcanic caldera and there's a crater there. Sure. 846 00:40:55.920 --> 00:40:58.119 And there's a lake in it. There's water just sitting there. 847 00:40:58.480 --> 00:40:59.619 Yeah, ready to kill you. 848 00:40:59.659 --> 00:41:04.309 Now, if that water knew that... or it had access 849 00:41:04.550 --> 00:41:08.570 to the ocean below, it would go like that. But 850 00:41:08.610 --> 00:41:14.250 it doesn't know. It's trapped in this. It thinks it 851 00:41:14.309 --> 00:41:17.139 has reached the low ground, because water always finds the 852 00:41:17.179 --> 00:41:19.300 lowest spot. It thinks it has reached the low ground, 853 00:41:20.300 --> 00:41:23.619 but it doesn't know that it can get lower. And so, 854 00:41:24.380 --> 00:41:25.940 like I said, I lose sleep wondering. 855 00:41:26.380 --> 00:41:28.980 And part of the problem is that because the new 856 00:41:29.000 --> 00:41:30.960 vacuum expands at the speed of light, we can't see 857 00:41:30.980 --> 00:41:35.519 it coming because light can't outpace it the first indication 858 00:41:35.860 --> 00:41:38.239 we get would be it's too late. 859 00:41:38.199 --> 00:41:39.760 So it sounds like there in a sense there's nothing 860 00:41:39.800 --> 00:41:44.670 to fear because it'll just happen that's not going to 861 00:41:44.710 --> 00:41:47.849 help me well meaning i think a thing to fear 862 00:41:47.929 --> 00:41:50.250 you can't even watch it happen yeah it'll just be 863 00:41:50.289 --> 00:41:51.829 we'll have been a thing and then not a thing 864 00:41:51.869 --> 00:41:52.849 that's not so bad. 865 00:41:52.909 --> 00:41:55.429 Yeah yeah i mean i don't prefer it. 866 00:41:57.019 --> 00:41:59.829 But we're a simulation anyway, so... Yeah, but one that. 867 00:41:59.719 --> 00:42:03.050 We really love being in. All right, what else you got? 868 00:42:03.369 --> 00:42:04.469 All right. 869 00:42:05.269 --> 00:42:08.210 Let's... Questions from the internet. Yes. 870 00:42:08.269 --> 00:42:09.289 Let's read this question. 871 00:42:09.329 --> 00:42:09.570 Ready? 872 00:42:12.070 --> 00:42:18.159 D61636 on Instagram asks, how was the Phoenix cluster discovered 873 00:42:18.199 --> 00:42:20.980 and why hasn't it devoured our solar system? 874 00:42:21.880 --> 00:42:25.869 Ooh, okay. I... I hope you know the answer to this. No, 875 00:42:25.889 --> 00:42:27.489 I don't know what the Phoenix Cluster is. 876 00:42:28.090 --> 00:42:34.170 Well, I guess that's another thing to fear. No, I 877 00:42:34.210 --> 00:42:34.889 don't know what. 878 00:42:34.809 --> 00:42:37.989 The Phoenix Cluster is. I know what the Phoenix Nebula is. Oh, 879 00:42:38.030 --> 00:42:38.360 what is it? 880 00:42:38.510 --> 00:42:42.989 It's a rather beautiful star-forming nebula that, I guess it's 881 00:42:43.010 --> 00:42:46.780 some hundreds of light years away. It's quite pretty. 882 00:42:48.139 --> 00:42:48.900 Looks like a phoenix. 883 00:42:49.199 --> 00:42:50.699 If it hears you say that, I think it will 884 00:42:50.719 --> 00:42:51.059 like it. 885 00:42:51.079 --> 00:42:56.170 Yeah. All right, here's another question. Evo Lucas asks. Wait, wait, 886 00:42:56.329 --> 00:42:59.909 let me back up for a minute. So, I don't 887 00:42:59.929 --> 00:43:03.630 know if this answers that specific question, but it relates 888 00:43:03.690 --> 00:43:07.869 to it. Sure. If a black hole shows up somewhere, 889 00:43:08.889 --> 00:43:11.960 it doesn't automatically become some kind of huge vacuum sucking 890 00:43:12.019 --> 00:43:15.860 up everything that it didn't previously suck in before. given 891 00:43:15.880 --> 00:43:18.929 the mass that it once was. So black holes are 892 00:43:19.030 --> 00:43:24.409 not giant sucking machines. If the sun became a black hole, 893 00:43:25.289 --> 00:43:26.690 all the planets won't all of a sudden just get 894 00:43:26.809 --> 00:43:27.670 sucked into the sun. 895 00:43:27.929 --> 00:43:28.989 But we would be harmed. 896 00:43:29.320 --> 00:43:30.780 Well, it would be cold. 897 00:43:31.199 --> 00:43:32.019 It would be very cold. 898 00:43:32.059 --> 00:43:33.019 That's the only change. 899 00:43:33.039 --> 00:43:34.099 Like super

cold. 900 00:43:34.139 --> 00:43:36.159 Super cold. As cold as it gets. As cold as 901 00:43:36.239 --> 00:43:36.679 is possible. 902 00:43:36.699 --> 00:43:38.760 So is this how we reassure people after the vacuum 903 00:43:38.780 --> 00:43:39.380 decay thing? 904 00:43:39.400 --> 00:43:42.010 Now I get why people are afraid of science. The 905 00:43:42.030 --> 00:43:43.630 more you know, the more there is to fear. 906 00:43:43.949 --> 00:43:45.750 So if in this cluster there's some black hole they 907 00:43:45.769 --> 00:43:47.489 might have read about, I haven't gotten the latest on that, 908 00:43:47.929 --> 00:43:51.050 but if that's the case, you needn't fear freshly formed 909 00:43:51.070 --> 00:43:51.489 black holes. 910 00:43:51.869 --> 00:43:52.110 Right. 911 00:43:52.369 --> 00:43:56.530 Because the gravity, the reason why black holes are scary 912 00:43:56.550 --> 00:43:58.440 is because you can get very close to them because 913 00:43:58.460 --> 00:44:00.360 they're very small. And when you get close to them, 914 00:44:00.380 --> 00:44:04.389 you feel... extraordinary gravitational effects on you. But if you 915 00:44:04.510 --> 00:44:07.800 maintain the distance you've always had from that object, it 916 00:44:07.820 --> 00:44:08.679 makes no difference to you. 917 00:44:08.719 --> 00:44:10.880 Like if a black hole was in Chicago, would we 918 00:44:10.920 --> 00:44:11.840 be fine here in New York? 919 00:44:11.960 --> 00:44:14.260 How big is the black hole? The size of a 920 00:44:14.480 --> 00:44:21.260 nice shoes. In, yeah. It would systematically eat the Earth. Yeah, 921 00:44:21.280 --> 00:44:23.659 that would be like the mass of Jupiter, I'm guessing. Yeah, yeah, yeah. 922 00:44:23.699 --> 00:44:26.239 So what if it was the size of a dime? 923 00:44:26.659 --> 00:44:28.059 So what if it was the size of a dime, 924 00:44:28.079 --> 00:44:28.860 would that destroy the Earth? 925 00:44:28.900 --> 00:44:30.219 That would be the mass of more than the Earth. 926 00:44:32.239 --> 00:44:34.380 Earth is a black hole the size of like a grape. 927 00:44:34.619 --> 00:44:36.300 It's nine millimeters in diameter. 928 00:44:36.519 --> 00:44:40.280 So a pomegranate seed black hole. 929 00:44:40.679 --> 00:44:43.789 That sounds rough too. The types of black hole that 930 00:44:43.829 --> 00:44:47.369 the Large Hadron Collider would produce when it collides beams, 931 00:44:47.769 --> 00:44:50.579 those would be so infinitesimally small that it shouldn't be 932 00:44:50.619 --> 00:44:50.980 a problem. 933 00:44:52.590 --> 00:44:54.610 They should decay instantly for one thing. 934 00:44:54.630 --> 00:44:56.849 Very reassured. 935 00:44:56.869 --> 00:45:00.329 You should be okay. You'll probably be okay. 936 00:45:00.690 --> 00:45:02.989 If it's edible, if a black hole was the size 937 00:45:03.010 --> 00:45:04.429 of something edible, we would all be dead. 938 00:45:04.530 --> 00:45:06.130 Yeah, exactly. Yeah, it fits in your mouth. I did 939

00:45:06.150 --> 00:45:07.750 think of a way to be scared. Systematically, I mean, 940 00:45:07.769 --> 00:45:09.750 you'd have to eat all the earth in its vicinity. 941 00:45:10.809 --> 00:45:12.639 You would systematically. But how long? 942 00:45:12.760 --> 00:45:15.500 Oh, and so like, but it would be minutes or seconds? 943 00:45:16.639 --> 00:45:16.739 Uh. 944 00:45:17.320 --> 00:45:19.559 Fractions of a second, I would guess. Oh, again, not 945 00:45:19.579 --> 00:45:20.880 so bad. The speed of light. But we'll have to 946 00:45:20.940 --> 00:45:24.760 do the calculation, I think. Yeah, but quickly. Oh, good. 947 00:45:26.030 --> 00:45:26.710 Time for another question. 948 00:45:26.730 --> 00:45:27.550 Yeah, yeah, let's do it. 949 00:45:30.409 --> 00:45:31.170 Vojta. 950 00:45:31.869 --> 00:45:32.309 Oh, no, wait. 951 00:45:32.489 --> 00:45:35.300 We never read Evo Lucas. When it comes to the 952 00:45:35.340 --> 00:45:39.059 multiverse theory, is there any way to know the ages 953 00:45:39.099 --> 00:45:41.480 of the various universes, or would they all be the 954 00:45:41.579 --> 00:45:42.280 same age? 955 00:45:42.420 --> 00:45:43.659 Hmm. Wow. 956 00:45:43.960 --> 00:45:48.550 So I think the answer is absolutely no way, given 957 00:45:48.570 --> 00:45:52.090 that there's no way to test whether they exist. 958 00:45:52.269 --> 00:45:56.880 So here's an interesting fact of science. Generally, if you 959 00:45:56.909 --> 00:46:00.139 don't know anything, your first question is the simplest. Does 960 00:46:00.179 --> 00:46:03.400 it exist? Then when you confirm that it exists, then 961 00:46:03.420 --> 00:46:05.619 you ask the next round of questions. How long has 962 00:46:05.659 --> 00:46:08.840 it existed? Will it die? Then you go, how big 963 00:46:08.909 --> 00:46:12.250 is it? What are the properties? So right now, we 964 00:46:12.690 --> 00:46:15.639 don't even know if multiverses exist, much less start handing 965 00:46:15.679 --> 00:46:19.349 out ages to them. The idea is these things pop 966 00:46:19.389 --> 00:46:26.280 in and out of existence forever. in some metaclock. How 967 00:46:26.400 --> 00:46:28.219 would you know if there was another universe? 968 00:46:28.239 --> 00:46:30.219 Well, it also depends on the type of multiverse. I mean, 969 00:46:30.480 --> 00:46:32.079 there are many different types to choose from. 970 00:46:32.300 --> 00:46:35.480 What's an example, like five examples? 971 00:46:35.500 --> 00:46:36.639 Five examples, easy. 972 00:46:36.659 --> 00:46:39.440 So there's the quantum multiverse, the idea of many worlds 973 00:46:39.840 --> 00:46:44.199 that the universe splits into multiple realizations of itself at 974 00:46:44.239 --> 00:46:46.099 every little subatomic decision. 975 00:46:46.119 --> 00:46:46.659 Mm-hmm. 976 00:46:47.630 --> 00:46:49.489 That one is the same, they're all the same age 977 00:46:49.530 --> 00:46:52.869 because they all started from the same branching chain. 978 00:46:53.889

--> 00:46:56.500 Then you have the... This is the famous many worlds 979 00:46:56.559 --> 00:47:02.000 interpretation that came out of the physicists in Denmark. So 980 00:47:02.059 --> 00:47:03.679 they call it the Copenhagen interpretation. 981 00:47:04.320 --> 00:47:10.190 It's post-Copenhagen. It makes the same predictions as Copenhagen. This 982 00:47:10.210 --> 00:47:13.179 came out in the 60s and I'm blanking on the 983 00:47:13.199 --> 00:47:17.340 physicist's name. Anyway, so then you have the idea of 984 00:47:17.360 --> 00:47:22.250 the multiverse that expands from what I mentioned earlier in 985 00:47:22.269 --> 00:47:26.449 the show, the eternally inflating multiverse. So one part of 986 00:47:26.510 --> 00:47:29.650 it just stops inflating so crazily fast and just does 987 00:47:29.710 --> 00:47:33.530 regular big bang inflation. And those should just be appearing 988 00:47:33.719 --> 00:47:36.940 all the time in that greater multiverse. One cool thing 989 00:47:36.980 --> 00:47:39.260 about those is that it may be possible to detect 990 00:47:39.280 --> 00:47:43.929 them if you happen to have two universes that kind 991 00:47:43.949 --> 00:47:47.340 of appeared like champagne bubbles and overlapped in the very beginning. 992 00:47:47.360 --> 00:47:48.760 Intersected. And merged. 993 00:47:49.179 --> 00:47:53.960 You would see rings on the cosmic microwave background radiation, 994 00:47:54.019 --> 00:47:56.739 sort of coffee stains of where they interacted back in 995 00:47:56.760 --> 00:47:59.489 the beginning. And we haven't seen them yet, but we 996 00:47:59.510 --> 00:48:01.030 will keep looking. 997 00:48:01.170 --> 00:48:06.130 A stained, coffee-stained universe. Somebody's a poet. Oh, there's another 998 00:48:06.170 --> 00:48:09.630 one where the actual space-time that you're in has pockets 999 00:48:10.150 --> 00:48:14.860 of non-causally connected expanding sections. So in other words, we 1000 00:48:14.900 --> 00:48:17.570 look out to our horizon, but beyond that horizon, there's 1001 00:48:17.610 --> 00:48:21.090 a whole other universe but part of our space time, 1002 00:48:21.110 --> 00:48:23.530 but we don't have access to it. And so that 1003 00:48:23.889 --> 00:48:28.170 there's this huge fabric of space time and just universes 1004 00:48:28.710 --> 00:48:31.789 dotting the space within it. And so. 1005 00:48:32.130 --> 00:48:33.909 And that type should be, they all should be the 1006 00:48:33.949 --> 00:48:34.250 same age. 1007 00:48:34.269 --> 00:48:35.650 Exactly. They started with the same Big Bang. Exactly, that 1008 00:48:35.670 --> 00:48:37.719 would be the same Big Bang that birthed it. That's three. 1009 00:48:37.909 --> 00:48:39.570 But my favorite one is the one where it's just 1010 00:48:39.610 --> 00:48:43.280 this frothy foam that is birthing universes back and forth. 1011 00:48:43.659 --> 00:48:47.619 And just for completeness, number five, the... the fecund universe 1012 00:48:47.659 --> 00:48:50.059 of Lee Smolin where black holes, when they form, they 1013 00:48:50.119 --> 00:48:51.179 create new universes. 1014 00:48:52.340 --> 00:48:54.900 Because inside of a black hole, the mathematics tells you 1015 00:48:55.320 --> 00:49:00.530 a whole other space-time emerges. Because you fall in, you'll 1016 00:49:00.829 --> 00:49:03.550 get to that after you see the future history of 1017 00:49:03.590 --> 00:49:07.670 the universe from which you came unfold. No. I got 1018 00:49:07.909 --> 00:49:08.710 shivers just then. 1019 00:49:08.869 --> 00:49:12.280 Yeah, yeah. So the answer is we don't know, but 1020 00:49:12.340 --> 00:49:13.980 some of our ideas are really great. 1021 00:49:15.079 --> 00:49:17.449 We've got to stop it here. You've been watching, if 1022 00:49:17.489 --> 00:49:21.239 you've seen this on YouTube, or otherwise listening. to StarTalk, 1023 00:49:21.920 --> 00:49:25.130 a Cosmic Queries edition. I've been your host, Neil deGrasse Tyson, 1024 00:49:25.150 --> 00:49:28.929 your personal astrophysicist. I think Eugene Mermin, Eugene, thanks for 1025 00:49:28.969 --> 00:49:29.409 coming back. 1026 00:49:29.449 --> 00:49:30.539 Thank you very much for having me. 1027 00:49:30.570 --> 00:49:32.170 Call me sometimes. I will. All right, you're in Boston now. 1028 00:49:32.190 --> 00:49:34.750 I'm going to start texting you science questions. 1029 00:49:34.869 --> 00:49:37.969 Okay, then I know you're alive. You're going to say, 1030 00:49:38.190 --> 00:49:41.670 you up? Yeah, I will. I'll be like, how does 1031 00:49:41.710 --> 00:49:44.469 the universe work, Neil? I've had a bar with some 1032 00:49:44.550 --> 00:49:48.369 friends we want to know. Exactly, exactly. And I think 1033 00:49:48.389 --> 00:49:52.610 my friend and colleague, Matt O'Dowd, who's got his own 1034 00:49:52.690 --> 00:49:57.760 YouTube channel on PBS Digital Studios, and it's called... Space Time. 1035 00:49:57.780 --> 00:49:59.699 Space Time. If I type in Space Time, it goes 1036 00:49:59.739 --> 00:50:02.900 to you. Type Australian. It doesn't go to Einstein's theory. 1037 00:50:03.179 --> 00:50:03.800 It goes to you. 1038 00:50:04.619 --> 00:50:07.340 We're number three or something like that. Or you can 1039 00:50:07.360 --> 00:50:08.260 go straight to YouTube and type in. 1040 00:50:08.260 --> 00:50:10.280 Okay, work harder. You might become number one on that. 1041 00:50:10.559 --> 00:50:12.380 Great having you. Thanks for being on. It's really fun. 1042 00:50:12.420 --> 00:50:14.960 All right, good. So as always, I bid you to 1043 00:50:15.400 --> 00:50:18.860 keep looking up. This is StarTalk.