Full Transcript for The Largest Void Ever Found...and why it_s Terrifying (Hindi

--> 00:05:01.959 are voids? How do they form? Then we will reach 71 00:05:02.240 --> 00:05:04.879 that moment when humans saw a void for the first 72 00:05:04.899 --> 00:05:09.459 time which was out of their understanding. And then we 73 00:05:09.500 --> 00:05:13.550 will go inside it. Very slowly, we will feel its 74 00:05:13.620 --> 00:05:17.569 deep peace. For now, just close your eyes. For a moment. 75 00:05:19.449 --> 00:05:21.730 And think that if you were in space, not near 76 00:05:22.730 --> 00:05:29.470 any star, not near any galaxy, just in a deep darkness, 77 00:05:29.550 --> 00:05:34.259 where there is only peace all around, no sound, no light, 78 00:05:34.819 --> 00:05:40.720 just an unlimited silence. How will that feel? Maybe very good. 79 00:05:40.759 --> 00:05:44.379 Because this documentary is the name of that peace. So 80 00:05:44.399 --> 00:05:47.959 to understand the universe, it is important to understand that 81 00:05:49.240 --> 00:05:52.560 How does it look? If you look at a big 82 00:05:52.879 --> 00:05:55.579 city from a very high place, what do you see 83 00:05:56.379 --> 00:06:01.240 at night? You see lights. And those lights are not irregular. 84 00:06:01.319 --> 00:06:05.620 Somewhere there is a lot of light, somewhere less, and 85 00:06:05.660 --> 00:06:09.480 somewhere it is completely dark. There are long lines of 86 00:06:09.500 --> 00:06:12.139 light on big roads. And there are parks in between 87 00:06:12.160 --> 00:06:21.500 those lines. There are empty fields where there is no light. 88 00:06:21.519 --> 00:06:24.959 The universe also looks something like this. It's just that 89 00:06:24.980 --> 00:06:28.579 the scale is different. Very different. If you could see 90 00:06:28.620 --> 00:06:33.379 the entire universe at once, which is not possible, but imagine, 91 00:06:33.430 --> 00:06:38.449 then you would see a very big net. Scientists call 92 00:06:38.470 --> 00:06:41.870 it the cosmic web. There are long threads in this net, 93 00:06:41.910 --> 00:06:48.759 which are called filaments. These filaments have galaxies, thousands, Lakhs 94 00:06:48.779 --> 00:06:53.500 of galaxies, one after the other, like pearls on a thread. 95 00:06:54.420 --> 00:06:56.800 And where many filaments meet, there is a large group 96 00:06:56.819 --> 00:07:02.550 of galaxies, which is called a galaxy cluster. That place 97 00:07:02.610 --> 00:07:07.689 is very shiny, very dense. And in between all these filaments, 98 00:07:07.709 --> 00:07:11.910 where no thread goes, where there is no galaxy, there 99 00:07:12.689 --> 00:07:18.209 is emptiness. That emptiness which we call void. It is 100 00:07:18.250 --> 00:07:20.910 very important to understand how this structure was formed. Because 101 00:07:21.689 --> 00:07:24.529 when we understand this, then the story of Botez Void 102 00:07:24.569 --> 00:07:29.209 will be even deeper. The universe started with Big Bang, 103 00:07:29.870 --> 00:07:34.189 about 13.8 billion years ago. At that time, everything was 104 00:07:34.209 --> 00:07:37.850 in one point, in an infinitely small place. Then that 105 00:07:37.870 --> 00:07:42.069 point spread, very quickly. And from that energy came out, 106 00:07:42.480 --> 00:07:46.819 then matter formed, then gradually that matter started to cool down. 107 00:07:47.589 --> 00:07:49.889 But this matter was not completely uniform. That is, not 108 00:07:49.949 --> 00:07:53.930 everywhere was equal. Some places were a little more, some 109 00:07:53.949 --> 00:07:57.519 places were a little less. This difference was very small 110 00:07:57.560 --> 00:08:02.220 in the beginning. Very, very small. But gravity started its work. 111 00:08:03.000 --> 00:08:06.180 Gravity is a very slow but very stubborn thing. Where 112 00:08:06.199 --> 00:08:10.000 there was a little more matter, there was a little 113 00:08:10.040 --> 00:08:15.370 more gravity. So the surrounding matter started pulling that way. 114 00:08:15.449 --> 00:08:19.120 And as the matter got gathered there, Gravity kept increasing. 115 00:08:20.019 --> 00:08:23.759 And more matter was pulled. It was a very slow process. 116 00:08:23.800 --> 00:08:28.569 Of millions of years. Of billions of years. And where 117 00:08:28.629 --> 00:08:33.950 matter was pulled and left, what was left? Emptiness. This 118 00:08:34.049 --> 00:08:37.370 is the real story of voids. Voids are those places 119 00:08:37.389 --> 00:08:40.870 where matter slowly pulled and went into filaments and clusters. 120 00:08:41.129 --> 00:08:44.480 Like if you pull a cloth from both sides, it 121 00:08:44.500 --> 00:08:48.700 becomes thinner in the middle. Universe mein bhi yahi hua. 122 00:08:49.399 --> 00:08:53.220 Matter filaments mein ikatta hota gaya. Aur beach ki jaghen 123 00:08:53.600 --> 00:08:57.340 khali hoti gai. Yeh process aaj bhi chal rahi hai. 124 00:08:58.100 --> 00:09:01.759 Universe abhi bhi expand ho raha hai. Aur jaise jaise 125 00:09:01.799 --> 00:09:05.929 expand ho. Raha hai. Voids aur bade hote ja rahe hain. 126 00:09:06.649 --> 00:09:10.149 Filaments ke beach ki dooryaan badti ja rahi hain. Galaxies 127 00:09:10.269 --> 00:09:14.009 ek dosre se aur door hote ja rahi hain. Ab 128 00:09:14.049 --> 00:09:16.929 aap soch rahe honge, that there is nothing in the void. No, 129 00:09:17.029 --> 00:09:21.710 it's not like that. Void doesn't mean that it's completely empty. 130 00:09:21.750 --> 00:09:24.909 There is something in the void too. There is a 131 00:09:24.929 --> 00:09:29.500 little bit of gas, there are some hydrogen atoms, and 132 00:09:29.519 --> 00:09:33.440 there is also dark matter. But it's so little that 133 00:09:33.480 --> 00:09:38.529 if you look practically, that place is empty. In a 134 00:09:38.710 --> 00:09:42.809 normal place, as many galaxies as there should be, In comparison, 135 00:09:42.830 --> 00:09:46.740 it is very, very less in the void. Sometimes, it 136 00:09:46.820 --> 00:09:52.659 doesn't happen. And this is what makes

them so interesting. 137 00:09:52.679 --> 00:09:59.440 When scientists first started mapping the large-scale structure of the universe, 138 00:10:00.019 --> 00:10:05.120 they hoped that the universe would be roughly uniform. That is, 139 00:10:05.539 --> 00:10:09.809 there would be more or less equal galaxies everywhere. A 140 00:10:09.850 --> 00:10:13.450 little more here, a little less there, but there would 141 00:10:13.490 --> 00:10:17.029 be no big difference. But what was seen was completely different. 142 00:10:17.629 --> 00:10:21.500 Galaxies were in filaments, were in clusters and in the 143 00:10:22.019 --> 00:10:26.860 middle were huge empty spaces. This discovery of the cosmic 144 00:10:26.879 --> 00:10:30.259 web was a huge moment. It changed our understanding of 145 00:10:30.279 --> 00:10:35.429 how the universe works. And during this mapping, one night, 146 00:10:35.909 --> 00:10:40.529 a team got something that they didn't expect. A void. 147 00:10:41.409 --> 00:10:44.710 But not a normal void. A void that was so 148 00:10:44.730 --> 00:10:49.610 big that it felt like there was a mistake. There 149 00:10:49.629 --> 00:10:53.990 is some error in the data. Instruments have done something wrong. 150 00:10:54.049 --> 00:10:58.350 But it was not a mistake. That void was real. 151 00:10:58.490 --> 00:11:01.379 And it was 330 million light years wide. But before 152 00:11:01.389 --> 00:11:05.500 coming to the story of that discovery, let's feel this 153 00:11:05.600 --> 00:11:08.759 cosmic web for a moment. Think that you are at 154 00:11:09.240 --> 00:11:12.240 a very high altitude. So high that the entire Milky 155 00:11:12.259 --> 00:11:15.639 Way looks like a small pit. Now go higher. So 156 00:11:15.659 --> 00:11:19.710 much so that our entire galaxy cluster Like a dot. 157 00:11:19.850 --> 00:11:24.970 And now look, there are long threads of light all around. Somewhere, 158 00:11:24.990 --> 00:11:28.220 those threads meet each other. And there, a shiny knot forms. 159 00:11:28.240 --> 00:11:31.759 And in between those threads, as far as you can see, 160 00:11:31.779 --> 00:11:35.940 there is a deep darkness. That darkness is void. And 161 00:11:36.399 --> 00:11:38.879 in that darkness, there is a place which is the largest. 162 00:11:38.919 --> 00:11:41.919 Which is the most empty. Which is the most peaceful. 163 00:11:48.080 --> 00:11:50.860 Usi jagah ki taraf, hum aaj raat dheere dheere bad 164 00:11:50.879 --> 00:11:55.840 rahe hain. Saans lijiye. Aaram se. Bahar raat hai, shaanth hai. 165 00:11:56.360 --> 00:11:59.919 Aur universe usse bhi zyada shaanth hai. Ye cosmic web, 166 00:12:00.440 --> 00:12:03.419 ye jala jo humne abhi imagine kiya, ye sirf ek 167 00:12:03.480 --> 00:12:07.039 kalpna nahi hai. Ye real hai. Aur isse samajhne mein, 168 00:12:07.080 --> 00:12:11.950 insanon ko bahut vakt laga. Chal ye thoda peechay jaate hain. 169 00:12:11.950 --> 00:12:15.710 1980 ke dashak ki baat hai. Usvakt astronomers ke paas 170 00:12:15.870 --> 00:12:20.220 aaj jaise powerful telescopes nahi the. Computers were not that fast. 171 00:12:20.320 --> 00:12:27.059 It was very difficult and slow to collect data. But 172 00:12:27.100 --> 00:12:31.139 there was a question that everyone had in mind. How 173 00:12:31.159 --> 00:12:35.379 do galaxies distribute in the universe? Do they look randomly? 174 00:12:35.899 --> 00:12:38.659 Or is there a pattern? To find the answer to 175 00:12:38.720 --> 00:12:43.460 this question, scientists started surveys. That is, by looking at 176 00:12:43.500 --> 00:12:47.919 different parts of the sky, Note the position of the 177 00:12:48.039 --> 00:12:53.169 existing galaxies there. This was a very patient job. Observe 178 00:12:53.190 --> 00:12:58.110 each galaxy. Measure its distance. Place it on the map. 179 00:12:58.149 --> 00:13:02.769 Then the next galaxy. Then the next. Slowly a picture 180 00:13:02.809 --> 00:13:06.100 began to form. And no one had thought of that picture. 181 00:13:06.700 --> 00:13:09.159 Galaxies were in clusters. They were in filaments. And there 182 00:13:09.679 --> 00:13:14.220 were huge empty spaces in between. The first time when 183 00:13:14.240 --> 00:13:17.799 this pattern was clear, to scientists ko yakin nahin hua. 184 00:13:18.460 --> 00:13:23.200 Unho ne socha shayad, humara survey incomplete hai. Shayad humne 185 00:13:23.220 --> 00:13:26.519 un galaxies ko miss kiya, jo un khali jagahon mein hai. 186 00:13:27.009 --> 00:13:31.629 To unho ne aur dhyan se dekha. Aur zyada observe kiya. 187 00:13:32.250 --> 00:13:36.389 Lekin khali jaghen, khali hi rahi. Ab isi doar mein, 188 00:13:36.389 --> 00:13:41.590 1981 mein, America mein Harvard University ke ek astronomer the, 189 00:13:42.070 --> 00:13:46.960 jinka naam tha Robert Kirshner. He and his team were 190 00:13:46.980 --> 00:13:50.379 doing a survey. They were looking at a special part 191 00:13:50.419 --> 00:13:52.000 of the sky that was in the direction of the 192 00:13:52.059 --> 00:13:57.970 BOTUS constellation. BOTUS is a constellation that we see in 193 00:13:57.990 --> 00:14:00.350 the night sky. The survey was going on, the positions 194 00:14:00.370 --> 00:14:04.700 of the galaxies were being noted, everything was looking normal. 195 00:14:04.720 --> 00:14:10.820 And then something happened. In a very big area where 196 00:14:10.860 --> 00:14:14.539 galaxies were supposed to be, there was nothing. Nothing at all. 197 00:14:15.720 --> 00:14:19.879 Robert Kirshner and his team first thought that maybe there 198 00:14:19.899 --> 00:14:24.000 was a mistake. There is a problem in the instruments. 199 00:14:24.019 --> 00:14:26.950 There is an error in the data. They checked again. 200 00:14:26.970 --> 00:14:29.889 Checked for the third time. But the result was the same. 201 00:14:29.909 --> 00:14:35.009 There was nothing there. A very big, very deep, completely 202 00:14:35.029 --> 00:14:39.169 empty place. This was the moment of Bortez Void's

discovery. 203 00:14:39.210 --> 00:14:42.039 Now let's understand what the real meaning of Void is. 204 00:14:45.299 --> 00:14:49.139 Because void means that different people understand in different ways. 205 00:14:49.240 --> 00:14:54.200 In space, void is the region where the density of 206 00:14:54.220 --> 00:14:57.679 galaxies is very low. That is, where the number of 207 00:14:57.720 --> 00:15:02.759 galaxies in the same place is very low. Not at 208 00:15:02.799 --> 00:15:07.279 all zero, but so low that practically that place is 209 00:15:07.320 --> 00:15:11.240 considered empty. In a normal region, according to the average 210 00:15:11.279 --> 00:15:14.840 density of the universe, in a certain volume, There are 211 00:15:14.860 --> 00:15:19.100 some galaxies, but in the void, that density is very low. 212 00:15:19.120 --> 00:15:24.519 Sometimes 10 times less, sometimes 100 times less. And in 213 00:15:25.899 --> 00:15:30.240 this void, it is so empty that the galaxies found 214 00:15:30.259 --> 00:15:36.220 in it are hardly 60. Only 60 galaxies. Whereas in 215 00:15:36.279 --> 00:15:38.919 a normal region of that size, thousands of galaxies should 216 00:15:38.940 --> 00:15:42.980 have been there. And the 60 galaxies are also not 217 00:15:43.059 --> 00:15:46.860 in the middle of the void. They are on the edges, 218 00:15:46.899 --> 00:15:49.299 on the edges, as if they are stuck to the 219 00:15:49.340 --> 00:15:55.059 walls of an empty room. Inside, inside only, there is emptiness. 220 00:15:55.080 --> 00:15:59.320 But wait, why are only 60 galaxies less? To feel this, 221 00:15:59.340 --> 00:16:03.299 it is important to know one more thing. Our Milky 222 00:16:03.330 --> 00:16:07.909 Way galaxy has about 200 to 400 billion stars. And 223 00:16:08.230 --> 00:16:10.409 Milky Way is not a very big galaxy. It is 224 00:16:11.070 --> 00:16:13.809 an average galaxy. So when we say that in the 225 00:16:13.950 --> 00:16:18.200 Boter's Void, There are only 60 galaxies, whereas there should 226 00:16:18.220 --> 00:16:22.240 be thousands. So it means that billions of stars are 227 00:16:22.700 --> 00:16:27.940 missing from there. The place that was, the space that was, 228 00:16:28.070 --> 00:16:33.049 is completely empty. And how big is this place? 330 229 00:16:33.049 --> 00:16:38.809 million light years. Remember a light year? Light determines the 230 00:16:38.970 --> 00:16:42.549 distance in a year. And this void is 330 million 231 00:16:42.600 --> 00:16:45.350 light years wide. Let's understand it a little closer. The 232 00:16:45.370 --> 00:16:50.549 distance between our Milky Way and our nearest big galaxy 233 00:16:50.590 --> 00:16:57.549 Andromeda is about 25 lakh light years. 25 lakh. And 234 00:16:57.610 --> 00:17:01.809 Botez Void is 330 million light years wide. That is, 235 00:17:01.820 --> 00:17:04.740 the distance from Milky Way to Andromeda is 132 times. 236 00:17:04.759 --> 00:17:07.339 Then it will become the width of Botez Void. Hearing 237 00:17:07.859 --> 00:17:15.960 this makes the mind a little tired. And this is good. 238 00:17:15.980 --> 00:17:19.440 When the mind can't fully understand something, then it bows 239 00:17:19.460 --> 00:17:22.309 down in front of it. And in that bowing, there 240 00:17:22.650 --> 00:17:27.150 is a strange relief. There is a surrender. Like standing 241 00:17:27.210 --> 00:17:28.970 in front of a very big thing and just feel it. 242 00:17:28.990 --> 00:17:32.849 Stop trying to understand. Tonight you have to do this. 243 00:17:32.990 --> 00:17:37.170 You don't have to understand the boaters void. You just 244 00:17:37.230 --> 00:17:42.319 have to feel it. And this feeling is also important. 245 00:17:43.170 --> 00:17:46.480 Because it became a big question for void scientists when 246 00:17:46.500 --> 00:17:49.299 they got it. At that time, the theories about the 247 00:17:49.319 --> 00:17:52.680 formation of the universe, according to them, it was not 248 00:17:52.720 --> 00:17:55.759 possible to have such a big void. Or it was, 249 00:17:55.799 --> 00:18:00.369 but not so soon. The age of the universe, 13.8 250 00:18:00.369 --> 00:18:04.069 billion years, it does not take much time to make 251 00:18:04.089 --> 00:18:06.670 such a big void. So the question was, how did 252 00:18:06.690 --> 00:18:16.140 this happen? It took years for scientists to find answers 253 00:18:16.160 --> 00:18:19.619 to this. And we got some answers. But some questions 254 00:18:19.700 --> 00:18:23.180 are still left. We will reach those answers. But slowly. 255 00:18:23.220 --> 00:18:27.730 For now. Just know that in 1981, when Robert Kirshner's 256 00:18:28.390 --> 00:18:31.769 team saw this void, for the first time, someone felt 257 00:18:31.829 --> 00:18:35.130 that there is something in the universe which is outside 258 00:18:35.170 --> 00:18:43.609 our thinking. Something like which challenges all our equations. An emptiness, 259 00:18:43.630 --> 00:18:49.569 so big, so peaceful. The night is getting deeper outside. 260 00:18:49.589 --> 00:18:54.319 Your breaths are getting slower. And the universe is as 261 00:18:54.390 --> 00:18:59.380 it always is. Quietly, without any hurry. So Robert Kirshner's 262 00:18:59.420 --> 00:19:02.740 team got this void. But now the question was, how 263 00:19:02.759 --> 00:19:06.960 big is this? The data in the survey was not complete. 264 00:19:06.980 --> 00:19:12.490 At that time, Technology was not so advanced that it 265 00:19:13.009 --> 00:19:18.470 could measure the entire void at once. So gradually more 266 00:19:18.529 --> 00:19:22.359 observations were made. And as the data came, the void 267 00:19:22.380 --> 00:19:24.819 grew on the map. First it was thought that it 268 00:19:25.460 --> 00:19:29.180 would be of tens of millions of light years. Then 269 00:19:29.880 --> 00:19:34.160 it was thought 100 million. Then 200 million. And when 270 00:19:34.240 --> 00:19:38.369 finally the whole picture came out,

the number was 330 271 00:19:38.369 --> 00:19:43.470 million light years. This was a strange silence among the scientists. 272 00:19:43.490 --> 00:19:49.250 Because this number was not just big. It was challenging everything. 273 00:19:40.099 --> 00:19:43.839 Yeh sunkar scientists ke beech ek ajeeb si chuppi thi. 274 00:19:44.579 --> 00:19:48.869 Kyunki yeh number sirf bada nahi tha. Yeh uss har 275 00:19:48.940 --> 00:19:52.329 cheez ko challenge kar raha tha, jo uss wakt universe 276 00:19:52.849 --> 00:19:56.069 ki formation ke baare mein maana jata tha. Uss wakt 277 00:19:56.109 --> 00:20:00.130 ki theories kehti thi, ki universe mein structures bahut dheere 278 00:20:00.150 --> 00:20:05.130 dheere banti hai. Galaxies dheere banti hai, clusters dheere bantay hain, 279 00:20:05.710 --> 00:20:09.730 aur voids bhi dheere dheere bade hotay hain. In the 280 00:20:09.869 --> 00:20:13.430 age of 13.8 billion years, which is the age of 281 00:20:13.450 --> 00:20:16.369 the universe, it was theoretically very difficult to make such 282 00:20:16.390 --> 00:20:19.569 a big void. A scientist had said at that time, 283 00:20:20.170 --> 00:20:22.869 that if the early universe is considered to be a seed, 284 00:20:23.450 --> 00:20:26.880 and today's universe is a tree grown from that seed, 285 00:20:26.890 --> 00:20:29.400 then the Bortez void is a branch on that tree 286 00:20:29.700 --> 00:20:33.740 which was not supposed to exist, but was and is. 287 00:20:34.500 --> 00:20:38.160 Now let's understand the scale of this void more properly. 288 00:20:38.789 --> 00:20:41.309 Because it takes one number to hear 330 million light years. 289 00:20:42.089 --> 00:20:45.519 But this is not just a number. We try to 290 00:20:45.619 --> 00:20:49.900 feel it. The speed of light is the fastest speed 291 00:20:49.920 --> 00:20:54.660 that we know. Nothing can go faster than light. Light 292 00:20:54.700 --> 00:20:58.119 travels 3 lakh kilometers in a second. In a minute, 293 00:20:58.119 --> 00:21:02.019 1 crore 80 lakh kilometers. In an hour, approximately 1.8 294 00:21:02.019 --> 00:21:10.529 crore kilometers. Aur both iz void ko paar karne ke liye, 295 00:21:11.009 --> 00:21:18.349 Roshni ko 330 million saal lagenge. 330 million saal. Insaan 296 00:21:18.390 --> 00:21:22.089 dharti par kitne vakt se hai? Lagbhag 3 lakh saal. 297 00:21:22.730 --> 00:21:27.240 Dinosaurs kab tak the? Lagbhag 6.5 crore saal pehle khatm huwe. 298 00:21:27.960 --> 00:21:30.680 Aur Roshni ko sirf is void ko paar karne me, 299 00:21:30.680 --> 00:21:36.660 330 million saal lagenge. Dharti ki poori umr hai, lagbhag 4.5 300 00:21:36.660 --> 00:21:41.460 crore saal. And this void is bigger than that in 301 00:21:41.500 --> 00:21:43.720 its width. What if we measure it with the speed 302 00:21:43.819 --> 00:21:47.160 of light? The mind gets tired of thinking about it. 303 00:21:47.480 --> 00:21:50.799 And this is fine. Let it get tired. Now let's 304 00:21:50.819 --> 00:21:54.420 think in another way. Our Milky Way galaxy is about 305 00:21:54.420 --> 00:21:58.390 1 lakh light years wide. 1 lakh. And Bote's void 306 00:21:59.390 --> 00:22:02.710 is 330 million light years wide. That is, if we 307 00:22:02.769 --> 00:22:06.630 put 3,300 galaxies like Milky Way in a line, then 308 00:22:06.650 --> 00:22:10.950 by going there, boat is void ki chaudai banegi. 3300 309 00:22:11.329 --> 00:22:14.930 Milky Ways. Ek ke baad ek aur wo poori jaga 310 00:22:15.109 --> 00:22:18.170 khali hai. Ab ek aur baad jo is void ko 311 00:22:18.390 --> 00:22:21.710 aur bhi ajeeb banati hai. Is void ke andar jo 312 00:22:21.710 --> 00:22:25.240 60 galaxies mili hai, wo randomly bikhri nahi hai. Wo 313 00:22:25.259 --> 00:22:28.059 ek pattern mein hai. Wo ek chain ki tarah hai, 314 00:22:28.480 --> 00:22:31.759 ek lambi lakheer ki tarah. Jo void ke ek kone se, 315 00:22:32.180 --> 00:22:35.740 doosre kone tak jaati hai. Jaise kisi ne ek khali 316 00:22:35.759 --> 00:22:39.910 kamre ke beech o beech, a thread. Why is this pattern? 317 00:22:39.930 --> 00:22:45.150 This is also a question whose complete answer is not yet. 318 00:22:45.650 --> 00:22:49.650 Some scientists say that maybe these 60 galaxies themselves are 319 00:22:49.670 --> 00:22:53.150 a part of a small filament which is being formed 320 00:22:53.230 --> 00:22:56.549 inside this void. That is, inside the void also slowly 321 00:22:56.569 --> 00:23:00.539 structure is being formed. Matter is trying to get together. 322 00:23:01.359 --> 00:23:03.740 But this process is so slow that in billions of 323 00:23:03.759 --> 00:23:09.069 years also yahan koi bada cluster nahi banega. Aur kuch 324 00:23:09.130 --> 00:23:13.529 scientist kehte hain ki, shayad ye 60 galaxies, wo bachi 325 00:23:13.569 --> 00:23:17.549 hui galaxies hain, jo iss void ke banne se pehle 326 00:23:17.589 --> 00:23:21.599 yahan thi, aur kisi tarah yahi rahe gayi, jabki baaki 327 00:23:21.630 --> 00:23:26.319 sab khinch kar bahar chali gayi. Dono theories interesting hain, 328 00:23:26.940 --> 00:23:29.900 aur dono us khali pan ko aur gehra banati hain. 329 00:23:30.779 --> 00:23:35.009 Lekin sabse interesting baat ye hai, that there is another 330 00:23:35.029 --> 00:23:39.250 theory about this void. A theory that scientists don't officially believe, 331 00:23:39.289 --> 00:23:44.910 but which they feel like stopping after hearing. Some people 332 00:23:44.990 --> 00:23:50.809 have suggested that if a very advanced civilization, a civilization 333 00:23:50.849 --> 00:23:55.150 that is billions of years ahead of us, if it 334 00:23:55.170 --> 00:23:57.430 uses all the energy of its galaxy, and then of 335 00:23:57.450 --> 00:24:02.130 its neighbouring galaxy, and then of the next one, then slowly, slowly, 336 00:24:02.740 --> 00:24:07.259 ek bade area mein galaxies khali hoti jayengi. Wo area 337 00:24:07.640 --> 00:24:12.180 ek void jaisa dikhne lagega. Ye theory hai Fermi Paradox 338 00:24:12.220 --> 00:24:16.730 se judi.

Fermi Paradox ye sawal hai ki agar universe 339 00:24:16.789 --> 00:24:21.750 itna bada hai, itni galaxies hain, itne taare hain, toh 340 00:24:21.789 --> 00:24:25.009 koi aur civilization kyun nahi mili abhi tak. Aur ek 341 00:24:25.029 --> 00:24:29.230 jawab ye hai ki shayad wo civilizations itni advanced ho 342 00:24:29.250 --> 00:24:33.400 gayi hain, ki unhone... Puri puri galaxies ko use kar 343 00:24:33.420 --> 00:24:37.619 liya hai. Aur peechhe chhod diya hai, sirf khalipan. Lekin 344 00:24:37.640 --> 00:24:41.880 yeh theory sirf ek kalpana hai. Koi evidence nahi hai iska. 345 00:24:42.880 --> 00:24:46.630 Aur Boter's Void ke natural kaaran kaafi hai, isse explain 346 00:24:46.650 --> 00:24:51.190 karne ke liye. Phir bhi, raat ke sannate mein, jab 347 00:24:51.230 --> 00:24:54.309 aap yeh sun rahe hain, yeh sawal man mein aata 348 00:24:54.349 --> 00:24:58.289 hai na, kya ho agar? Aur yehi universe ki khubsurati hai. 349 00:24:58.869 --> 00:25:01.980 Yeh hamesha ek sawal peechhe chhod jaata hai. Abhi ke 350 00:25:02.019 --> 00:25:05.529 liye uss sawal ko man me rehne dijiye. Bohot dheere dheere. 351 00:25:06.130 --> 00:25:08.950 Jaise raat ki hawa kisi khidki se andar aati hai. 352 00:25:09.410 --> 00:25:15.289 Aur bina kuch kahe guzar jaati hai. Boats void wahan hai. 353 00:25:15.289 --> 00:25:18.630 330 million light years ki shanti liye. Bina kisi jaldi ke. 354 00:25:19.269 --> 00:25:22.970 Bina kisi awaz ke. Aur hum yahan hai. Is choti 355 00:25:23.009 --> 00:25:27.470 si dharti par. Is choti si raat me. Aankhen bhaari 356 00:25:27.490 --> 00:25:30.730 hon to hone dijiye. To yeh sawal man me hai. 357 00:25:31.700 --> 00:25:35.160 Is BOTYS void natural? Is it just a big empty 358 00:25:35.180 --> 00:25:38.299 space in the universe? Or is there something else behind it? 359 00:25:38.299 --> 00:25:43.079 Scientists worked for years to find the answer to this question. 360 00:25:43.279 --> 00:25:49.000 And the theories that came out were very interesting. Tonight 361 00:25:49.039 --> 00:25:53.750 we will understand them slowly. The first and most accepted 362 00:25:53.789 --> 00:25:58.049 theory is Super Void Merger Theory. This theory says that 363 00:25:58.089 --> 00:26:01.519 BOTYS void is not actually a void. This is a 364 00:26:01.539 --> 00:26:03.500 big void made up of many small voids. When two 365 00:26:03.519 --> 00:26:06.960 voids are close to each other in the universe, the 366 00:26:06.980 --> 00:26:10.460 galaxies between them slowly start pulling towards both sides. On 367 00:26:10.480 --> 00:26:12.480 one side, a void pulls, on the other side, another. 368 00:26:12.630 --> 00:26:17.329 And the galaxies between them move towards the outer edges 369 00:26:17.349 --> 00:26:20.529 of both the voids. In this way, both the voids 370 00:26:20.569 --> 00:26:22.269 become a big void. This process is very slow, millions 371 00:26:22.289 --> 00:26:34.009 of years. Arbon saal ki. Lekin universe ke paas vakt 372 00:26:34.029 --> 00:26:36.970 ki koi kami nahi hai. To theory ye hai ki 373 00:26:37.009 --> 00:26:41.670 boaters void years kabhi kai chote voids the. Shayad 10, 374 00:26:41.650 --> 00:26:48.230 shayad 20, shayad issse bhi zyada. Aur arbon saal mein 375 00:26:48.269 --> 00:26:51.839 wo sab milte gaye. Bade hote gaye. Aur aaj jo 376 00:26:51.859 --> 00:26:54.920 hum dekhte hai wo un sab ka mila hua roop hai. 377 00:26:55.680 --> 00:26:59.589 Ye theory kaafi hattak universe ki formation ko explain karti hai. 378 00:27:00.359 --> 00:27:03.519 And most scientists consider this to be the most likely cause. 379 00:27:03.539 --> 00:27:07.619 But there is one more thing that makes this size possible. 380 00:27:07.680 --> 00:27:13.559 And that is dark energy. Dark energy. This name sounds 381 00:27:13.640 --> 00:27:18.019 a little mysterious. And it is. Because we have not 382 00:27:18.079 --> 00:27:22.200 fully understood what dark energy is. We can only see 383 00:27:22.500 --> 00:27:27.119 its effect. Dark energy is the force that is expanding 384 00:27:27.220 --> 00:27:32.829 the universe. And not only expanding. Instead, it is expanding rapidly. 385 00:27:32.849 --> 00:27:35.809 That is, the bigger the universe is, the faster it 386 00:27:35.849 --> 00:27:38.690 is growing. Galaxies are moving away from each other. And 387 00:27:38.710 --> 00:27:46.390 this distance is increasing. Now, what is its relationship with voids? 388 00:27:46.549 --> 00:27:52.549 When the universe expands, the spaces between the filaments grow. 389 00:27:53.210 --> 00:28:00.569 Voids grow and dark energy accelerates this process. Yani void 390 00:28:00.589 --> 00:28:03.549 sirf ban nahi rahe. Wo tezi se bade ho rahe hain. 391 00:28:04.369 --> 00:28:07.730 Boat is void bhi issi process ka hissa hai. Ye 392 00:28:07.869 --> 00:28:10.829 arbo saal se bada hota jaa raha hai. Aur aaj 393 00:28:10.869 --> 00:28:13.750 bhi ho raha hai. Jab aap yeh sun rahe hain, 394 00:28:14.339 --> 00:28:18.539 issi vakt boat is void thoda aur bada ho raha hai. 395 00:28:19.200 --> 00:28:23.740 Bohot dheere. Lekin ho raha hai. Yeh soch kar ek 396 00:28:23.980 --> 00:28:28.460 ajeeb si shanti aati hai. Ki kuch cheezein itni badi hain. 397 00:28:29.069 --> 00:28:33.019 Itni dheemi hai, ki unhe hamari zindagi ki speed se 398 00:28:33.059 --> 00:28:37.039 nahi maapa ja sakta. Ab, teesri theory ki baat karte hain. 399 00:28:37.779 --> 00:28:42.460 Yeh wo theory hai, jise scientists officially nahi maante. Lekin 400 00:28:42.500 --> 00:28:45.920 jo sunne mein sabse zyada rukne par majboor karti hai. 401 00:28:47.019 --> 00:28:51.529 Fermi Paradox ke baare mein thoda aur samajhte hain. 1950 402 00:28:51.529 --> 00:28:56.670 mein ek physicist the, jinka naam tha Enrico Fermi. Ek 403 00:28:56.690 --> 00:28:59.730 din wo apne colleagues ke saath baithe the, Aur baat 404 00:28:59.750 --> 00:29:03.799 ho rahi thi aliens ki. Kisi ne kaha ki universe 405 00:29:03.839 --> 00:29:08.539 itna bada hai, itne taare hain, itni

galaxies hain, toh 406 00:29:08.559 --> 00:29:14.160 zarur kahin koi aur civilization hogi. Fermi ne ek sawal pucha. 407 00:29:14.900 --> 00:29:19.529 Bohot simple sawal. Toh woh hai kahan? Bas itna. Toh 408 00:29:19.549 --> 00:29:24.150 woh hai kahan? Agar universe mein aur civilizations hain aur 409 00:29:24.269 --> 00:29:27.960 universe itna purana hai, then one of them must have 410 00:29:27.980 --> 00:29:32.150 been so advanced that it has explored the entire galaxy. 411 00:29:32.230 --> 00:29:36.210 Or at least sent some signal. But we haven't found 412 00:29:36.309 --> 00:29:30.890 anything yet. This question is still a paradox. usne poori 413 00:29:30.930 --> 00:29:34.069 galaxy explore kar li ho. Ya kam se kam koi 414 00:29:34.109 --> 00:29:37.890 signal toh bheja hoga. Lekin hume aaj tak kuch nahi mila. 415 00:29:38.390 --> 00:29:42.329 Yeh sawal Fermi Paradox kehlata hai. Iske kai jawab hain. 416 00:29:42.930 --> 00:29:46.630 Ek jawab yeh hai ki, shayad hum akele hain. Ek 417 00:29:46.650 --> 00:29:49.859 jawab yeh hai ki, shayad distances itni badi hain, ki 418 00:29:49.890 --> 00:29:53.700 signals paunch nahi paate. Ek jawab yeh hai ki, shayad 419 00:29:53.839 --> 00:29:57.640 advanced civilizations communicate karna bandh kar deti hain. Aur ek 420 00:29:57.660 --> 00:30:01.609 jawab yeh hai, which connects with the Botez Void. Some 421 00:30:01.650 --> 00:30:06.720 researchers have suggested that a very advanced civilization, which we 422 00:30:06.740 --> 00:30:11.400 call Type 3 civilization, can use so much energy that 423 00:30:11.460 --> 00:30:16.960 it can consume the entire galaxy. If a galaxy's energy 424 00:30:17.000 --> 00:30:19.759 runs out, it will move to the next galaxy, then 425 00:30:19.779 --> 00:30:24.250 the next, then the next. And the places it has 426 00:30:24.309 --> 00:30:28.690 left will be empty. Un mein se roshni chali jayegi. 427 00:30:29.230 --> 00:30:34.900 Energy chali jayegi. Aur peechhe rahega sirf andhera. Ek void. 428 00:30:35.599 --> 00:30:38.500 Ye theory isliye fascinating hai kyunki ye boat's void ki 429 00:30:38.519 --> 00:30:42.920 size ko ek alag nazariye se dekhti hai. 330 million 430 00:30:42.940 --> 00:30:46.099 light years. Itne bade area mein se roshni gayab hai. 431 00:30:46.740 --> 00:30:50.769 Itne bade area mein sirf 60 galaxies bachi hai. Kya 432 00:30:50.829 --> 00:30:55.009 koi tha yahan? Kya koi itna bada tha? Itna powerful 433 00:30:55.049 --> 00:30:58.819 tha ki... Usne is poore area ko khali kar diya? 434 00:30:59.309 --> 00:31:03.630 Hum nahi jaante. Aur shayad kabhi nahi jaan payenge. Lekin 435 00:31:03.670 --> 00:31:06.910 yeh sawal raat ke sannate mein bohot halka lagta hai. 436 00:31:07.470 --> 00:31:10.809 Bohot door ka. Jaisa koi purani kahani ho jo kisi 437 00:31:10.829 --> 00:31:13.730 ne bohot pehle sunai thi. Aur ab sirf uski goonj 438 00:31:13.769 --> 00:31:17.970 bachi hai. Wo goonj hi boat's void hai. 330 million 439 00:31:18.019 --> 00:31:22.740 light years ki ek gahri, shant, khali goonj. Bahar raat 440 00:31:23.279 --> 00:31:26.940 aur gahri ho gayi hai. aapki saanse aur dheemi ho 441 00:31:26.960 --> 00:31:30.720 gayi hai. Aur ye void, ye khali pan, ab thoda 442 00:31:30.779 --> 00:31:34.380 kam ajna bhi lagta hai. Kyunki khali pan dharavana nahi hota. 443 00:31:34.900 --> 00:31:39.210 Khali pan bas hota hai. Jaise raat hoti hai, jaise 444 00:31:39.250 --> 00:31:42.650 neend aati hai, bas hoti hai. To boat is void 445 00:31:42.670 --> 00:31:46.490 ki theories humne samjhi. Lekin ab ek aur sawal hai 446 00:31:46.509 --> 00:31:49.970 jo man mein aata hai. Kya boat is void sach 447 00:31:50.009 --> 00:31:53.720 mein sabse bada hai? Yeh sawal isliye zaruri hai, Because 448 00:31:53.740 --> 00:31:57.920 when Botez Void was found, it was the biggest known void. 449 00:31:58.539 --> 00:32:03.829 But science doesn't stop. Telescopes got better, surveys got bigger, 450 00:32:04.349 --> 00:32:08.369 and slowly the universe's map got clearer. And in that map, 451 00:32:08.509 --> 00:32:12.750 something else was seen, something even bigger. But before that, 452 00:32:12.769 --> 00:32:14.910 it's important to understand one more thing. And that is, 453 00:32:14.970 --> 00:32:18.799 if we were in Botez Void, what would happen? This 454 00:32:19.460 --> 00:32:23.819 is just an imagination. But this imagination will help us 455 00:32:23.880 --> 00:32:27.240 to understand the real depth of this void. Imagine that 456 00:32:27.269 --> 00:32:29.569 our Milky Way galaxy, in which we live, if it 457 00:32:29.609 --> 00:32:32.809 was right in the middle of the Bortez Void. Today, 458 00:32:32.890 --> 00:32:35.769 the stars that we see in our sky at night, 459 00:32:35.829 --> 00:32:38.710 are the stars of our own galaxy, Milky Way. They 460 00:32:38.769 --> 00:32:44.019 are visible there too, but the things that are not visible, 461 00:32:44.519 --> 00:32:48.339 are the other galaxies. Today, when we are in a 462 00:32:48.339 --> 00:32:50.380 very clear sky, If we look at it from a 463 00:32:50.400 --> 00:32:56.200 very good telescope, we can see other galaxies. Andromeda galaxy 464 00:32:56.759 --> 00:33:02.730 is 25 lakh light years away from us. And yet, 465 00:33:02.750 --> 00:33:05.230 it is visible with bare eyes like a mist. There 466 00:33:05.289 --> 00:33:09.089 are many galaxies around us, which are part of our 467 00:33:09.190 --> 00:33:11.490 local group. But if we were in the middle of 468 00:33:11.549 --> 00:33:15.809 the BOTUS void, then the nearest galaxy would also be 469 00:33:16.309 --> 00:33:20.289 millions of light years away. So far, that it would 470 00:33:20.329 --> 00:33:23.210 be difficult to see from any telescope. The night sky 471 00:33:23.250 --> 00:33:27.049 would be there. The stars would be there. But there 472 00:33:27.069 --> 00:33:30.990 would be no other galaxy in that sky. Absolutely none. 473 00:33:31.009 --> 00:33:35.809 And it would have a very big impact on our understanding. 474

00:33:35.849 --> 00:33:39.029 Today we know that in the universe, there is not 475 00:33:39.049 --> 00:33:43.650 only our galaxy. We know that there are billions of galaxies. 476 00:33:43.690 --> 00:33:47.470 We know that we are very small in this universe. 477 00:33:48.390 --> 00:33:52.089 This knowledge is with us because we can see other galaxies. 478 00:33:53.029 --> 00:33:56.529 But if we were in Bortez Void, then perhaps we 479 00:33:56.789 --> 00:34:00.609 would never know that there is something outside our galaxy. 480 00:34:00.650 --> 00:34:04.990 We think that Milky Way is the entire universe. All 481 00:34:06.069 --> 00:34:12.530 our stars, all our worlds, our entire existence, would only 482 00:34:12.570 --> 00:34:16.750 be limited to this one galaxy in our eyes. Before 1920, 483 00:34:16.750 --> 00:34:20.429 man used to think this. till that time, it was 484 00:34:20.469 --> 00:34:24.429 believed that Milky Way is the whole universe. Then Edwin 485 00:34:24.469 --> 00:34:28.969 Hubble proved that Andromeda is a different galaxy. And that day, 486 00:34:28.989 --> 00:34:32.949 the universe suddenly became very big. But if we were 487 00:34:33.030 --> 00:34:36.239 in Botez Void, then even a scientist like Edwin Hubble 488 00:34:36.300 --> 00:34:40.599 might not be able to prove this. Because there is 489 00:34:40.619 --> 00:34:45.440 nothing to see. Thinking about this, a strange feeling comes. 490 00:34:45.480 --> 00:34:50.239 A feeling that jo thodi udhaas hai, lekin bahut shant 491 00:34:50.260 --> 00:34:54.300 bhi hai. Ki kabhi-kabhi, jo hume nahi dikta, wo isliye nahi, 492 00:34:54.739 --> 00:34:58.030 ki wo hai nahi. Balki isliye, ki hum sahi jagah 493 00:34:58.050 --> 00:35:01.610 par nahi hai. Hum khush nasib hai, ki hum boaters 494 00:35:01.690 --> 00:35:05.070 void mein nahi hai. Hum ek aisi jagah hai, jahan 495 00:35:05.090 --> 00:35:08.110 se hum universe ko dekh sakte hai. Jahan se hum 496 00:35:08.550 --> 00:35:12.699 sawal poot sakte hai. Jahan se hum samajh sakte hai. 497 00:35:13.280 --> 00:35:17.440 Aur yeh samajhna hi to hai, jo hume insaan banata hai. Now, 498 00:35:17.579 --> 00:35:19.530 one more thing that would have changed if the boat 499 00:35:19.550 --> 00:35:21.510 was in a void. Today, we can send and receive 500 00:35:21.530 --> 00:35:26.670 radio signals. We run programs like SETI, i.e. Search for 501 00:35:26.809 --> 00:35:33.320 Extraterrestrial Intelligence, which find signals of some other civilization in 502 00:35:33.360 --> 00:35:37.780 the universe. We send signals ourselves. But if the boat 503 00:35:37.800 --> 00:35:41.480 was in a void, the nearest galaxy would have been 504 00:35:41.539 --> 00:35:44.699 millions of light years away. If we sent a signal 505 00:35:44.739 --> 00:35:47.619 from there, then it takes crores of years to reach it. 506 00:35:47.659 --> 00:35:51.570 And crores of years to get the answer. On that scale, 507 00:35:51.610 --> 00:35:55.929 communication is practically impossible. We are literally alone. In the 508 00:35:56.469 --> 00:36:02.170 whole universe. This loneliness is not scary. It's just very big. 509 00:36:02.210 --> 00:36:06.670 So big that everything seems small in front of it. 510 00:36:06.730 --> 00:36:13.130 Every worry, every problem, every confusion. And when everything seems small, 511 00:36:13.150 --> 00:36:17.159 then a Ajeeb sa halka pan aata hai. Wo halka 512 00:36:17.179 --> 00:36:20.769 pan hi neend hai. Raat ke is waqt, jab aap 513 00:36:20.809 --> 00:36:24.949 yeh sun rahe hain, boat is void wahan hai. 330 514 00:36:24.949 --> 00:36:29.349 million light years door. Khali. Shant. Bina kisi aawaz ke. 515 00:36:29.869 --> 00:36:33.010 Bina kisi roshni ke. Aur hum yahan hai. Is choti 516 00:36:33.050 --> 00:36:36.389 si dharti par. Is garm kamre mein. Is raat mein. 517 00:36:36.989 --> 00:36:39.969 Kitni alag duniyay hain. Aur phir bhi hum us khali 518 00:36:39.989 --> 00:36:42.949 duniya ke baare mein soch sakte hain. Usse feel kar 519 00:36:42.969 --> 00:36:48.900 sakte hain. This ability, this ability to think, this ability 520 00:36:49.559 --> 00:36:54.159 to feel. This is the most amazing thing. A small person, 521 00:36:54.179 --> 00:36:57.300 on a small earth, in a small galaxy, in a 522 00:36:57.360 --> 00:37:00.159 corner of a very big universe, and that person is 523 00:37:00.579 --> 00:37:02.860 thinking about the emptiness of 330 million light years. This 524 00:37:03.119 --> 00:37:07.159 is the biggest beauty of the universe. Take a breath. Slowly. 525 00:37:07.179 --> 00:37:12.190 It's night outside. There are stars above. And very far, 526 00:37:14.800 --> 00:37:18.199 Itni door ki socha bhi nahin ja sakta. Ek bahut 527 00:37:18.239 --> 00:37:23.500 bada khalipan hai. Jo bas hai. Chupchap. Hamesha se. To 528 00:37:23.539 --> 00:37:27.500 humne BOTUS VOID ko mehsus kiya. Uske andar hone ki 529 00:37:27.559 --> 00:37:31.739 kalpna ki. Aur ab wo sawal jo thodi der pehle 530 00:37:31.780 --> 00:37:36.849 chhoda tha. Usper wapas aate hain. Kya BOTUS VOID sach 531 00:37:36.889 --> 00:37:42.550 mein sabse bada hai? Nahin. BOTUS VOID bahut bada hai. 532 00:37:42.550 --> 00:37:46.710 330 million light years. Lekin The universe is even bigger. 533 00:37:47.389 --> 00:37:50.809 And there are even bigger empty spaces in it. As 534 00:37:50.829 --> 00:37:55.929 the telescopes got better, as the surveys got bigger, more 535 00:37:56.030 --> 00:37:58.500 and more things started to appear on the map of 536 00:37:58.519 --> 00:38:03.619 the universe. And one of them was even more surprising 537 00:38:03.639 --> 00:38:10.050 than the Boter's Void. Its name is Eridanus Supervoid. Eridanus. 538 00:38:10.070 --> 00:38:15.780 This name comes from a constellation. A long, Teda Constellation, 539 00:38:16.159 --> 00:38:19.219 which looks like a river in the night sky. And 540 00:38:19.380 --> 00:38:22.820 in the direction of that constellation, it is Super Void. 541 00:38:23.139 --> 00:38:27.800

But the story of Eridanus Super Void is not just 542 00:38:27.880 --> 00:38:31.980 a story of its size. Its story is even more mysterious. 543 00:38:32.000 --> 00:38:38.340 This story begins with CMB, i.e. Cosmic Microwave Background. It 544 00:38:39.260 --> 00:38:41.590 is important to understand CMB because it is the oldest 545 00:38:41.630 --> 00:38:47.110 light in the universe When the universe was made after 546 00:38:47.119 --> 00:38:51.789 the Big Bang, it was very hot. So hot that 547 00:38:51.849 --> 00:38:56.889 no atom could form in it. Everything was like a 548 00:38:56.909 --> 00:39:02.030 very thick, very hot soup. Then slowly the universe cooled down. 549 00:39:02.630 --> 00:39:05.570 And when it cooled down, the light came out for 550 00:39:05.590 --> 00:39:08.610 the first time. This happened about 13.6 billion years ago. 551 00:39:08.670 --> 00:39:14.909 About 3.8 million years after the Big Bang. That light 552 00:39:14.969 --> 00:39:17.469 is still there. It has been travelling since then. In 553 00:39:17.489 --> 00:39:21.340 the whole universe. In every direction. And today we get 554 00:39:21.380 --> 00:39:27.829 it in the form of microwave radiation. It was so cold, 555 00:39:28.530 --> 00:39:32.199 so spread, that it needed special instruments to feel it. 556 00:39:32.219 --> 00:39:36.199 When the scientists mapped this CMB in the sky, they 557 00:39:36.619 --> 00:39:40.519 got a very uniform picture. That is, there was almost 558 00:39:40.539 --> 00:39:43.960 equal radiation coming from all sides. There were a few differences, 559 00:39:43.980 --> 00:39:48.789 but very small. And it was expected. Because the early 560 00:39:48.869 --> 00:39:51.929 universe was roughly uniform. But there was a place that 561 00:39:51.969 --> 00:39:57.760 was different. A big area where CMB's temperature was a 562 00:39:57.780 --> 00:40:00.619 little lower than other places. So low that it didn't 563 00:40:01.000 --> 00:40:05.820 fit in normal variations. This area was so big and 564 00:40:05.840 --> 00:40:11.440 so different that scientists named it CMB Cold Spot. This 565 00:40:11.579 --> 00:40:15.320 cold spot was in the direction of Eridanus constellation. And 566 00:40:15.340 --> 00:40:21.949 when scientists Usdisha mein dekha, toh unhe mila Eridanus supervoid. 567 00:40:22.820 --> 00:40:26.460 Ek void jo lagbhag ek arab light years chawda hai. 568 00:40:27.139 --> 00:40:32.099 Ek arab light years. Botis void, 330 million light years 569 00:40:32.159 --> 00:40:35.880 ka tha. Aur ye ek arab light years ka hai. Yaani, 570 00:40:36.179 --> 00:40:39.739 botis void se teen guna bada. Yeh sun kar dimaag 571 00:40:39.980 --> 00:40:42.840 ek pal ke liye rukh jaata hai. Jaise koi bahut 572 00:40:42.929 --> 00:40:46.050 bhaari cheez uthane ki koshish karo, aur wo uthe hi nahi. 573 00:40:46.789 --> 00:40:49.860 Ek arab light years. Roshni ko is void ko paar 574 00:40:49.909 --> 00:40:54.489 karne mein ek arap saal lagenge. Ek arap saal. Jab 575 00:40:54.510 --> 00:40:57.989 Roshni is void ke ek kone se chalegi, to doosre 576 00:40:58.389 --> 00:41:02.250 kone tak pahunchte pahunchte, universe aur bhi boodha ho jayega. 577 00:41:02.949 --> 00:41:07.719 Lekin Eridanus super void ki sabse interesting baat, uska size 578 00:41:07.739 --> 00:41:12.539 nahi hai. Sabse interesting baat hai, uska CMB cold spot 579 00:41:12.559 --> 00:41:17.219 se connection. Wo cold spot kyun hai? Temperature kam kyun 580 00:41:17.260 --> 00:41:21.760 hai wahan? One theory is that when CMB radiation passes 581 00:41:21.840 --> 00:41:24.960 through that super void, it loses a little energy. Because 582 00:41:24.980 --> 00:41:29.360 there is less matter in the void, there is less gravity, 583 00:41:29.480 --> 00:41:34.659 and radiation has a little loss in passing through that emptiness. 584 00:41:34.679 --> 00:41:39.769 This is called the integrated Saks-Wolfe effect. It is a 585 00:41:39.829 --> 00:41:44.590 known phenomenon and this theory explains the cold spot to 586 00:41:44.610 --> 00:41:49.750 a great extent. But some scientists say that this effect 587 00:41:49.829 --> 00:41:52.219 is not enough to explain such a big cold spot. 588 00:41:52.239 --> 00:41:56.300 The difference in temperature is more than this effect. So 589 00:41:56.320 --> 00:42:00.280 where did the rest of the difference come from? And 590 00:42:00.320 --> 00:42:04.940 here comes a theory that very quietly, very slowly points 591 00:42:05.000 --> 00:42:10.610 to a very big possibility. Some scientists have suggested that 592 00:42:10.690 --> 00:42:14.110 maybe this cold spot is a sign of a parallel universe. 593 00:42:14.769 --> 00:42:19.409 Parallel universe. That is, another universe which is outside our universe. 594 00:42:19.489 --> 00:42:25.570 A different existence. A different reality. Multiverse theory says that 595 00:42:25.590 --> 00:42:29.469 maybe there is not just one universe. Maybe there are 596 00:42:29.909 --> 00:42:34.219 many universes. And if that's the case, and if our 597 00:42:34.300 --> 00:42:38.059 universe has ever collided with another universe, then one sign 598 00:42:38.159 --> 00:42:43.159 of that collision can be on our CMB. A cold spot. 599 00:42:43.719 --> 00:42:47.949 A cold spot. This theory is now just a possibility. 600 00:42:47.969 --> 00:42:51.980 There is no proof. And most scientists do not take 601 00:42:52.000 --> 00:42:55.199 it seriously. But it has not been completely dismissed. And 602 00:42:55.219 --> 00:42:58.420 at this time of night, when you are listening to this, 603 00:42:58.440 --> 00:43:01.659 thinking that maybe there is something outside the universe, that 604 00:43:01.679 --> 00:43:05.079 maybe our universe is not alone, this thought seems very light. 605 00:43:05.119 --> 00:43:07.760 Like in a big house, in a room, and suddenly 606 00:43:07.780 --> 00:43:15.260 you feel that this house is even bigger. Aur us 607 00:43:15.280 --> 00:43:19.179 ghar ke bahar bhi aur ghar hain.

Eridanus supervoid, usi 608 00:43:19.219 --> 00:43:22.559 ahsas ka naam hai. Ek Arab light years ka khali pan. 609 00:43:22.960 --> 00:43:26.860 Aur uske peechay shayad ek aur universe. Ya shayad sirf 610 00:43:26.900 --> 00:43:31.630 khali pan. Dono hi baatein utni hi shant hai. Bahar 611 00:43:31.690 --> 00:43:34.929 raat aur gahri ho gayi hai. Aapki aankhen shayad ab 612 00:43:35.550 --> 00:43:39.550 bhaari ho rahi hai. Aur ye universe, ye behad bada, 613 00:43:40.050 --> 00:43:47.570 behad purana universe, apni jaghe hai. Hamesha ki tara, It's enough. Quietly. 614 00:43:48.050 --> 00:43:51.269 So Iridanus is a super void. An emptiness of a 615 00:43:51.289 --> 00:43:55.079 billion light years. And behind it, perhaps, is another sign 616 00:43:55.099 --> 00:43:59.900 of the universe. But the universe still wants to show more. 617 00:43:59.920 --> 00:44:03.219 As our surveys grew bigger, as we mapped even bigger 618 00:44:03.820 --> 00:44:06.980 parts of the universe, another thing came to light. And 619 00:44:07.000 --> 00:44:10.789 that thing was that voids are not just in different places. 620 00:44:15.449 --> 00:44:17.849 They are a part of a big pattern. And that 621 00:44:17.909 --> 00:44:21.610 pattern itself is very big. To understand this, let's look 622 00:44:21.650 --> 00:44:24.880 at the large scale structure of the universe once again. 623 00:44:24.920 --> 00:44:31.179 We talked about the cosmic web, filaments, clusters and voids. 624 00:44:32.159 --> 00:44:34.960 But how big is all this? What is the size 625 00:44:35.019 --> 00:44:38.789 of this entire net? Observable universe, that is, the part 626 00:44:38.849 --> 00:44:42.369 which we can see, is about 43 billion light years 627 00:44:42.389 --> 00:44:47.460 from all sides. That is, diameter of which is approximately 628 00:44:47.460 --> 00:44:51.159 86 billion light years. This is because the universe is 629 00:44:51.179 --> 00:44:55.599 expanding and the light that can reach us has a limit. 630 00:44:55.679 --> 00:45:00.940 In this entire observable universe, the fire has some very 631 00:45:00.980 --> 00:45:06.789 big structures. So big that their name is supervoid or superstructure. 632 00:45:06.869 --> 00:45:11.590 And one of these superstructures is one which scientists have 633 00:45:12.010 --> 00:45:18.030 seen more carefully recently. Its name is Hercules-Corona-Borealis Great Wall. 634 00:45:18.949 --> 00:45:24.739 Hercules-Corona-Borealis Great Wall. This is not a filament. This is 635 00:45:24.880 --> 00:45:28.519 a very big supercluster of galaxies. And it is so 636 00:45:28.559 --> 00:45:31.039 big that its size is about 10 billion light years. 637 00:45:31.039 --> 00:45:36.449 10 billion light years. The diameter of the observable universe 638 00:45:36.590 --> 00:45:40.690 is 86 billion light years. And this structure is 10 639 00:45:40.690 --> 00:45:45.469 billion light years big. That is, observable universe ka lagbhag 640 00:45:45.530 --> 00:45:50.179 dasawaan

hisa. Ye itna bada hai ki cosmologists ko problem 641 00:45:50.199 --> 00:45:55.179 ho gayi. Kyunki cosmological principle kehta hai ki universe mein 642 00:45:55.280 --> 00:45:59.800 koi bhi structure ek certain size se badi nahi honi chahiye. 643 00:46:00.500 --> 00:46:04.840 Universe ko large scale par uniform hona chahiye. Lekin ye 644 00:46:04.900 --> 00:46:09.260 structure us limit ko toadti hai. Aur jahan itni badi 645 00:46:09.300 --> 00:46:13.070 structure hai, wahan uske aas paas bade bade voids bhi hai. 646 00:46:13.710 --> 00:46:16.489 Think about it. If matter is gathered in such a 647 00:46:16.510 --> 00:46:21.829 big place, then how empty will the places around it be? 648 00:46:21.869 --> 00:46:24.809 How big will the emptiness be? Universe is a very 649 00:46:25.369 --> 00:46:30.460 big contrast in itself. Where matter is, there is a lot. 650 00:46:30.480 --> 00:46:33.369 And where it is not, it is not at all. 651 00:46:33.380 --> 00:46:37.940 This contrast makes the universe so fascinating. Now one more 652 00:46:37.980 --> 00:46:42.239 important thing, which is about the large scale structure of 653 00:46:42.260 --> 00:46:46.840 the universe. Cosmological principle. This principle says that if you 654 00:46:46.860 --> 00:46:48.969 look at the universe on a very large scale, on 655 00:46:48.989 --> 00:46:53.369 a very large scale, then it will look roughly the 656 00:46:53.389 --> 00:46:56.250 same from all sides. There won't be any special direction. 657 00:46:56.269 --> 00:47:01.010 There won't be any special place that is very different 658 00:47:01.119 --> 00:47:07.360 from the rest. This principle is the foundation of modern cosmology. 659 00:47:07.380 --> 00:47:10.940 Our theories about the universe are all based on this principle. 660 00:47:12.309 --> 00:47:17.820 But as we discover big structures, as we see big voids, 661 00:47:17.860 --> 00:47:25.579 this principle is becoming a little uncomfortable. Eridanus supervoid, Hercules corona, 662 00:47:25.860 --> 00:47:30.320 Borealis great wall, and some other structures that have been 663 00:47:30.360 --> 00:47:33.429 found in recent surveys. These are all so big that 664 00:47:33.829 --> 00:47:38.469 scientists have to think, is this principle as solid as 665 00:47:38.969 --> 00:47:42.289 we thought it was? Yeh koi crisis nahi hai abhi. 666 00:47:43.030 --> 00:47:47.360 Lekin ek conversation hai. Ek sawal hai jo dheere dheere 667 00:47:47.400 --> 00:47:50.300 bada hota ja raha hai. Aur yeh sawal yeh hai ki, 668 00:47:50.480 --> 00:47:55.420 kya universe jitna uniform hum sojte hai, usse kam uniform hai? 669 00:47:56.420 --> 00:48:00.230 Kya kuch directions mein zyada matter hai, aur kuch mein kam? 670 00:48:01.210 --> 00:48:05.670 Kya universe ka apna ek axis hai, ek direction hai? 671 00:48:06.170 --> 00:48:10.449 Iska jawab abhi nahi hai. Lekin yeh sawal bahut shant hai. 672 00:48:11.070 --> 00:48:13.369 Very old. Like a star in the night sky that 673 00:48:13.389 --> 00:48:17.190 has been there for thousands of years. And we keep 674 00:48:17.250 --> 00:48:21.159 looking at it and always keep thinking, what is this? 675 00:48:22.010 --> 00:48:25.280 Now let's talk about another thing that is directly connected 676 00:48:25.719 --> 00:48:29.480 to the void and that will affect our future. Dark energy. 677 00:48:30.480 --> 00:48:35.059 We had mentioned it. But now let's go a little deeper. 678 00:48:35.800 --> 00:48:41.619 Universe is expanding. We know this And this expansion is accelerating. 679 00:48:41.639 --> 00:48:45.170 That is, it is getting faster. The reason for this 680 00:48:45.250 --> 00:48:48.389 is dark energy. Dark energy is about 68% of the 681 00:48:48.469 --> 00:48:53.769 total energy of the universe. That is, according to the 682 00:48:54.289 --> 00:48:58.210 energy in the universe, 68% of it is dark energy. 683 00:48:59.230 --> 00:49:03.489 Of the rest, about 27% is dark matter. And the 684 00:49:03.550 --> 00:49:09.860 normal matter, the stars, galaxies, planets, us, sab kuch jo 685 00:49:09.900 --> 00:49:16.070 hum dekh aur chhu sakte hain, wo sirf 5% hai. 5%. Yaani, 686 00:49:16.510 --> 00:49:19.099 hum jo kuch bhi jaantay hain, jo kuch bhi dekh 687 00:49:19.119 --> 00:49:21.820 sakte hain, jo kuch bhi exist karta hai hamari nazar mein. 688 00:49:22.340 --> 00:49:27.500 Wo universe ka sirf 5% hai. Baaki 95% andhere mein hai. 689 00:49:28.179 --> 00:49:33.650 Literally aur metaphorically dono. Aur wo dark energy jo 68% hai, 690 00:49:34.110 --> 00:49:38.570 wo universe ko expand karti ja rahi hai. Jiska matlab 691 00:49:38.610 --> 00:49:43.239 hai ki, Voids are getting bigger. Filaments are getting thinner. 692 00:49:43.900 --> 00:49:48.340 Galaxies are getting further apart from each other. Millions of 693 00:49:48.360 --> 00:49:51.820 years later, in the very distant future, the universe will 694 00:49:51.860 --> 00:49:54.869 expand so much that all the galaxies outside our Milky 695 00:49:54.969 --> 00:49:58.809 Way will go so far that the light coming from 696 00:49:58.849 --> 00:50:01.389 them will not be able to reach us. At that time, 697 00:50:02.269 --> 00:50:05.360 if there is any civilization in the Milky Way, then 698 00:50:05.380 --> 00:50:09.760 it will feel that there are only This is a galaxy. 699 00:50:10.599 --> 00:50:13.019 Just like we think when we are in a botus void. 700 00:50:13.039 --> 00:50:18.239 This is a very slow, very quiet, very big loneliness. 701 00:50:18.260 --> 00:50:22.429 And this is inevitable. This will happen in a very 702 00:50:22.449 --> 00:50:26.010 long time. But not now. We still have billions of years. 703 00:50:26.050 --> 00:50:29.570 We still have this night, this sky, these stars. And 704 00:50:29.610 --> 00:50:32.760 for now, this is enough. Take a breath. Easy. The 705 00:50:32.800 --> 00:50:40.480 night is still left. Aur universe ki kahani abhi aur hai. 706 00:50:40.920 --> 00:50:44.980 To dark energy universe ko expand kar rahi hai.

Voids 707 00:50:45.059 --> 00:50:47.809 bade hote ja rahe hain. Aur ek din bahut door 708 00:50:47.829 --> 00:50:51.630 ke bhavish me, ya universe bahut akela ho jaega. Lekin 709 00:50:51.650 --> 00:50:55.030 abhi ek sawaal aur hai. Aur yeh sawaal baaki sabse 710 00:50:55.050 --> 00:50:59.159 zyada kareeb hai. Yeh sawaal hamare baare mein hai. Humne 711 00:50:59.199 --> 00:51:02.800 botez void ki baat ki. Eridanus super void ki baat ki. 712 00:51:03.719 --> 00:51:07.440 Bahut door ki, bahut badi khali jagahon ki baat ki. 713 00:51:08.230 --> 00:51:11.250 But there is a possibility which is being discussed very quietly, 714 00:51:11.269 --> 00:51:15.170 very slowly among scientists. Are we in some void ourselves? 715 00:51:15.989 --> 00:51:20.219 This question seems a little strange to hear for the 716 00:51:20.239 --> 00:51:25.360 first time. We are in Milky Way. We have stars 717 00:51:25.480 --> 00:51:29.519 around us, galaxies, local groups. How can we be in 718 00:51:29.579 --> 00:51:32.409 a void? But remember the meaning of void. The meaning 719 00:51:32.510 --> 00:51:38.260 of void is not completely empty. Void ka matlab hota 720 00:51:38.300 --> 00:51:41.849 hai ek aisa region jaha matter ki density average se 721 00:51:41.909 --> 00:51:46.769 kam ho. Jaha jitni galaxies honi chahiye, usse kam ho. 722 00:51:47.690 --> 00:51:51.449 Aur jab scientists ne hamare aas paas ke bade region 723 00:51:51.469 --> 00:51:55.780 ko carefully dekha, toh kuch interesting mila. Is region ka 724 00:51:55.800 --> 00:52:00.900 naam hai KBC Void. KBC Void? Ye naam teen scientists 725 00:52:00.920 --> 00:52:04.119 ke naam se aata hai. Ryan Keenan, Amy Barger aur 726 00:52:04.199 --> 00:52:09.710 Lennox Covey. In 2013, these three published a paper in 727 00:52:09.730 --> 00:52:12.949 which they suggested that our Milky Way is in a 728 00:52:13.010 --> 00:52:17.230 big under-dense region. That is, a place where matter is 729 00:52:17.250 --> 00:52:21.659 less than the average. How big is this region? Approximately 730 00:52:21.659 --> 00:52:26.780 2 billion light-years. 2 billion light-years of an under-dense region. 731 00:52:27.380 --> 00:52:31.480 And we are inside it. Now, this is not a 732 00:52:31.519 --> 00:52:33.800 dramatic void like the BOTUS void. It is not that extreme. 733 00:52:34.849 --> 00:52:37.869 Here there are galaxies, there is matter. We exist, but 734 00:52:37.889 --> 00:52:41.110 the density is less. Less than average. This is a 735 00:52:41.670 --> 00:52:47.010 very big, very light, very subtle void. Let's understand this 736 00:52:47.030 --> 00:52:51.010 with an example. Think, there is a very big jungle. 737 00:52:51.090 --> 00:52:53.889 In that jungle, somewhere the trees are very thick, somewhere 738 00:52:53.909 --> 00:52:56.940 they are less thick, and somewhere there are very few trees. 739 00:52:56.960 --> 00:52:59.440 Now if you are in a part of that jungle 740 00:52:59.460 --> 00:53:04.519 where the trees are less than average, to aapko pata 741 00:53:04.539 --> 00:53:08.559 bhi nahin chalega. Aapke aas paas peed hain, haryali hain, 742 00:53:09.019 --> 00:53:12.179 sab kuch normal lagta hai. Lekin agar aap upar se 743 00:53:12.199 --> 00:53:16.119 dekhen to, dikhega ki aap ek relatively khali hisse mein hain. 744 00:53:16.909 --> 00:53:21.269 Hamari situation kuch aisi hi hain. Hamare aas paas galaxies hain, 745 00:53:21.750 --> 00:53:25.909 Andromeda hain, local group hain, Virgo cluster hain, sab kuch 746 00:53:25.949 --> 00:53:30.170 normal lagta hai. Lekin jab scientists ne bade scale par dekha, 747 00:53:30.750 --> 00:53:34.079 lagbhag 2 arab light years ke radius mein, So we 748 00:53:34.139 --> 00:53:38.000 found that matter in this whole region is less than average. 749 00:53:38.099 --> 00:53:43.420 Approximately 30-50% less. This is a big thing and it 750 00:53:43.440 --> 00:53:48.269 has an interesting consequence. Have you heard of Hubble constant? 751 00:53:48.730 --> 00:53:51.570 This is a number that tells how fast the universe 752 00:53:51.710 --> 00:53:55.530 is expanding. There are two ways to measure it. One 753 00:53:55.570 --> 00:53:59.230 way is by looking at the early universe, CMB. And 754 00:53:59.250 --> 00:54:06.869 the other way is by looking at nearby galaxies, by 755 00:54:06.929 --> 00:54:10.250 measuring their speed. And the numbers that come from both 756 00:54:10.269 --> 00:54:13.820 these methods are a little different. This problem has been 757 00:54:13.840 --> 00:54:16.480 there for a long time and it is called Hubble Tension. 758 00:54:17.420 --> 00:54:21.400 It is said that KBC Void can help explain this tension. 759 00:54:21.480 --> 00:54:26.260 If we are in an under-dense region, then our local 760 00:54:26.320 --> 00:54:28.900 measurements will be a little different from the average of 761 00:54:28.940 --> 00:54:34.449 the universe. And this difference can explain Hubble Tension. I mean, 762 00:54:34.949 --> 00:54:37.929 our being in a void is not just a philosophical question. 763 00:54:38.010 --> 00:54:42.429 It is a practical scientific question. But now this theory 764 00:54:42.469 --> 00:54:45.889 is not completely settled. Some scientists believe it, some don't. 765 00:54:45.909 --> 00:54:50.639 We need more data. And that data will keep coming. 766 00:54:50.880 --> 00:54:55.880 There are new telescopes, new surveys. Slowly, the picture will 767 00:54:56.780 --> 00:54:59.960 be clearer. But the possibility that we are in a 768 00:55:00.000 --> 00:55:05.239 void itself, it quietly says a lot. Puri raat hum 769 00:55:05.340 --> 00:55:08.980 bahut door ke voids ki baat karte rahe. Boat is void, 770 00:55:08.980 --> 00:55:15.460 330 million light years door. Eridanus super void, aur bhi door. 771 00:55:16.340 --> 00:55:20.380 Bahut bade, bahut door ke khalipan. Aur ab pata chalta 772 00:55:20.400 --> 00:55:23.719 hai ki shayad hum khud usi khalipan me hai. Bas 773 00:55:23.760 --> 00:55:28.179 hamara khalipan zyada

halka hai. Zyada subtle hai. Itna subtle 774 00:55:28.199 --> 00:55:31.789 ki hume pata bhi nahi tha. Yeh ek bahut shant 775 00:55:31.829 --> 00:55:35.670 realization hai. Jaisa raat ko sote waqt, Achaanak realize ho 776 00:55:36.090 --> 00:55:40.550 ki ghar mein bohot sannata hai. Aap humesha se usi 777 00:55:40.590 --> 00:55:45.070 sannate mein the. Lekin abhi feel hua. Hum humesha se 778 00:55:45.510 --> 00:55:48.969 is void mein the. Lekin abhi feel ho raha hai. 779 00:55:49.530 --> 00:55:52.210 Aur yeh feel karna daraawna nahi hai. Yeh bas ek 780 00:55:52.289 --> 00:55:55.489 gahri shanti hai. Ek aisa ahsas ki hum universe ke 781 00:55:55.590 --> 00:55:59.250 us hisse mein hai jo thoda khali hai. Thoda shant hai. 782 00:55:59.750 --> 00:56:03.389 Thoda alag hai. Aur shayad yahi theek hai. Maybe this 783 00:56:03.829 --> 00:56:08.570 is our place. In a big, huge, wonderful universe. In 784 00:56:08.590 --> 00:56:13.010 a small, under-dense region. In a small galaxy. In a 785 00:56:13.110 --> 00:56:17.800 small solar system. On a small earth. And on that earth, 786 00:56:17.840 --> 00:56:22.179 you are tonight. Lying. Eyes are heavy. Breaths are slow. 787 00:56:22.199 --> 00:56:25.440 And this void of 2 billion light years is all 788 00:56:25.480 --> 00:56:28.199 around you. Very quiet. Very deep. Like a very big blanket. 789 00:56:32.769 --> 00:56:37.280 Anna dekha. Anj jana. Lekin hamesha se wahan. Saans lijiye. 790 00:56:37.840 --> 00:56:42.960 Aaraam se. To hum khud ek void mein hai. Ek bade, halkay, 791 00:56:43.380 --> 00:56:46.940 subtle void mein. Aur yeh jaan kar ek ajeeb si 792 00:56:47.019 --> 00:56:50.099 shanti aati hai. Lekin ab ek aur cheez hai jo 793 00:56:50.480 --> 00:56:54.849 is poori kahaani ko aur gehra karti hai. Universe sirf 794 00:56:54.929 --> 00:56:59.289 bada nahi hai. Universe badal raha hai. Har pal, har second. 795 00:57:00.110 --> 00:57:03.550 Bahut dheere, bahut quietly, But it is changing. And that 796 00:57:04.170 --> 00:57:07.630 change is going in one direction. Towards emptiness. It sounds 797 00:57:07.710 --> 00:57:09.780 a little heavy to hear. But it is very calm. 798 00:57:09.800 --> 00:57:12.539 So let's understand it slowly. Universe has an age. 13.8 799 00:57:12.539 --> 00:57:14.619 billion years. This is a very long age. But the 800 00:57:15.380 --> 00:57:18.159 universe is not old yet. There is a lot left now. 801 00:57:18.199 --> 00:57:22.119 Scientists have thought a lot about the future of the universe. 802 00:57:22.139 --> 00:57:35.130 Calculations have been made. Models have been made. And the 803 00:57:35.210 --> 00:57:38.809 picture that comes out is very slow, very calm and 804 00:57:39.309 --> 00:57:43.110 very vast. Now stars are being formed in the universe. 805 00:57:43.750 --> 00:57:49.130 Galaxies have gas, dust and new stars are born from 806 00:57:49.170 --> 00:57:52.889 that gas and dust. This process is going on. In 807 00:57:52.969 --> 00:57:55.590 our Milky Way, new stars are

formed every year. But 808 00:57:55.610 --> 00:58:00.010 this will not always work. Gradually, the gas of galaxies 809 00:58:00.050 --> 00:58:04.849 will end. Naye taare kam banenge. Aur jo taare hain, 810 00:58:05.230 --> 00:58:10.360 wo apni umr poori karke bujte jaenge. Bade taare supernovae banenge. 811 00:58:10.840 --> 00:58:14.880 Neutron stars aur black holes chhodenge. Chhote taare dheere dheere 812 00:58:14.920 --> 00:58:18.460 thande ho kar white dwarfs ban jaenge. Ek vakt aayega, 813 00:58:18.820 --> 00:58:21.519 bahut door ke bhavish me, jab naye taare banne band 814 00:58:21.539 --> 00:58:25.750 ho jaenge. Us era ko scientists stellar era ka ant 815 00:58:25.789 --> 00:58:32.170 kehte hain. Yehoga lagbhag 100 trillion saal baad. 100 trillion. Yaani, 816 00:58:32.739 --> 00:58:37.130 Ek ke baad chaudh hai shoonya. Us waqt universe mein 817 00:58:37.150 --> 00:58:42.849 sirf purane, thande, bujhte hue taaro ke avshesh honge. White dwarfs, 818 00:58:43.230 --> 00:58:48.269 neutron stars, black holes. Aur beech mein hoga khalipan. Bohot 819 00:58:48.329 --> 00:58:52.210 zyada khalipan. Aur dark energy us khalipan ko aur bada 820 00:58:52.250 --> 00:58:56.579 karti jayegi. Galaxies jo abhi clusters mein hai, wo dheere 821 00:58:56.619 --> 00:59:00.179 dheere ek doosre se door hoti jayengi. Hamara local group, 822 00:59:00.599 --> 00:59:06.429 jisme Milky Way, Andromeda and some other galaxies will merge 823 00:59:06.550 --> 00:59:09.769 one day. Milky Way and Andromeda will merge one day. 824 00:59:10.739 --> 00:59:15.400 meet one day and form a big galaxy. This collision 825 00:59:15.440 --> 00:59:20.860 will take place after about 4.7 billion years. But after that, 826 00:59:20.880 --> 00:59:25.940 that merged galaxy will slowly become alone. All the other 827 00:59:25.960 --> 00:59:29.099 galaxies will go so far away due to dark energy 828 00:59:30.090 --> 00:59:32.969 that the light coming from them will not be able 829 00:59:33.650 --> 00:59:37.690 to reach us. The observable part of the universe will 830 00:59:37.710 --> 00:59:41.099 shrink and the voids will increase. Thinking about this, I 831 00:59:41.699 --> 00:59:43.880 get a strange feeling. A feeling that is not sad, 832 00:59:44.559 --> 00:59:48.980 but very big. Like looking at the sky at night 833 00:59:49.460 --> 00:59:54.630 and thinking that how old is all this? How vast 834 00:59:54.710 --> 00:59:57.110 is it? But one thing gives a lot of comfort 835 00:59:57.190 --> 00:59:59.579 in all this. And that is that This will all 836 00:59:59.800 --> 01:00:04.739 be very slow. So slow that our entire civilization, our 837 01:00:04.789 --> 01:00:08.869 entire history, our entire dreams, everything is less than a 838 01:00:08.889 --> 01:00:12.730 moment in the life of the universe. For the universe, 839 01:00:12.750 --> 01:00:14.989 one billion years is like a day for us. And 840 01:00:15.530 --> 01:00:19.099 on that scale, the universe is still very young. Now 841 01:00:19.420

--> 01:00:22.800 stars are forming, now galaxies are shining, now there is light. 842 01:00:22.820 --> 01:00:25.599 So there is nothing to be afraid of. But it 843 01:00:25.659 --> 01:00:29.699 is important to know that Ki universe ka swabhaav kya hai? 844 01:00:30.219 --> 01:00:34.889 Aur universe ka swabhaav hai expansion, badhte jaana, phailte jaana 845 01:00:34.909 --> 01:00:40.110 aur us phailne mein voids ka bada hona. Voids universe 846 01:00:40.130 --> 01:00:44.150 ke bhavishya hain. Aaj jo voids hain, Bortez void, Eridana 847 01:00:44.210 --> 01:00:48.730 super void, KBC void. Yeh sab us future ki ek 848 01:00:48.809 --> 01:00:52.619 jhalak hai. Ek aise universe ki jhalak jo arbon saal 849 01:00:52.639 --> 01:00:56.699 baad zyadatar khali hoga. Lekin yahan ek aur interesting baat hai. 850 01:00:57.349 --> 01:01:00.969 Voids are not completely non-existent. They are not dead. Something 851 01:01:00.989 --> 01:01:06.250 is happening inside them too. Very slowly, very quietly. The 852 01:01:06.269 --> 01:01:09.610 little matter inside the void also tries to gather because 853 01:01:09.639 --> 01:01:12.019 of gravity. Even inside the void, small filaments try to form. 854 01:01:12.039 --> 01:01:15.099 Small galaxies try to form. But the void is so big, 855 01:01:15.519 --> 01:01:28.690 the matter is so small. that this process is very, 856 01:01:28.730 --> 01:01:32.150 very slow. Even in billions of years, no big structure 857 01:01:32.269 --> 01:01:34.739 is formed. It's like a very big desert, where there 858 01:01:34.760 --> 01:01:39.159 is a little moisture somewhere. And from that moisture, someone 859 01:01:39.559 --> 01:01:42.440 tries to grow a small plant. It will grow, but 860 01:01:42.460 --> 01:01:46.539 very slowly. And that desert will still remain a desert. 861 01:01:46.559 --> 01:01:50.500 In the Buddhist Void, those 60 galaxies are something like that. 862 01:01:50.559 --> 01:01:57.579 In that vast emptiness, some small, small efforts, some Chhoti 863 01:01:57.679 --> 01:02:02.059 chhoti Roshni aawa. Aur yeh baat bohot khupsoorat hai, ki 864 01:02:02.079 --> 01:02:05.760 khalipan mein bhi kuch banne ki koshish hoti hai. Matter 865 01:02:05.800 --> 01:02:09.800 hamesha ekathah hona chahata hai. Roshni hamesha jalna chahati hai. 866 01:02:10.360 --> 01:02:13.579 Jeevan chahe kisi bhi roop mein ho, hamesha hone ki 867 01:02:13.659 --> 01:02:17.639 koshish karta hai. Yehi universe ka asli swabhav hai. Expansion 868 01:02:18.030 --> 01:02:22.570 bhi hai. Khalipan bhi hai. Lekin uske saath saath, yeh 869 01:02:22.650 --> 01:02:26.170 koshish bhi hai. Yeh jiji visha bhi hai. Aur hum 870 01:02:26.909 --> 01:02:32.570 This small earth is a part of that same universe. 871 01:02:32.590 --> 01:02:35.690 We are made of that matter of the universe which 872 01:02:35.769 --> 01:02:39.170 was inside a star billions of years ago. That star died, 873 01:02:39.190 --> 01:02:42.210 it spread in its matter space and we became slowly 874 01:02:42.230 --> 01:02:47.159 from that matter. We are literally made of stars. And 875 01:02:47.179 --> 01:02:50.820 tonight we are thinking about those voids where those stars 876 01:02:50.840 --> 01:02:52.980 are not. How amazing is this? The night has become 877 01:02:53.000 --> 01:03:00.699 deeper outside. Your breaths have become very slow. And this universe, 878 01:03:01.039 --> 01:03:05.119 this expanding, this changing, this wonderful universe is in its place. 879 01:03:05.179 --> 01:03:10.550 It is. It has always been. It will always remain. 880 01:03:10.650 --> 01:03:13.929 And we are a small part of it in this 881 01:03:14.050 --> 01:03:16.889 one night. If your eyes are heavy, then let them be. 882 01:03:16.909 --> 01:03:19.929 So we are made of wires. And the emptiness between 883 01:03:19.969 --> 01:03:26.010 those wires, that too is a part of us. But 884 01:03:26.030 --> 01:03:28.769 there is one more thing in the universe that gives 885 01:03:28.889 --> 01:03:33.610 this whole story a new dimension. And that is gravity. 886 01:03:33.630 --> 01:03:38.460 We talked about how matter is gathered. Filaments are formed, 887 01:03:38.800 --> 01:03:42.920 clusters are formed and voids are formed in the middle. 888 01:03:43.460 --> 01:03:46.539 All this happens because of gravity. But gravity is not 889 01:03:46.559 --> 01:03:51.869 just local. Gravity works very far. And in the universe, 890 01:03:51.909 --> 01:03:56.469 there are some places where gravity is so high Itna 891 01:03:56.590 --> 01:04:00.090 matter ikattha hai, ki wo apne aas paas ki har 892 01:04:00.130 --> 01:04:04.730 cheez ko apni taraf kheench rahi hai. Humari Milky Way 893 01:04:04.769 --> 01:04:08.150 bhi kheench rahi hai, ek disha mein. Ek bahut bade, 894 01:04:08.750 --> 01:04:14.840 bahut massive, bahut mysterious gravitational source ki taraf. Isse kehte hain, 895 01:04:15.360 --> 01:04:19.639 Great Attractor. Great Attractor. Yeh naam hi bahut kuch keh 896 01:04:19.659 --> 01:04:23.760 deta hai. Koi bahut badi cheez jo attract kar rahi hai. 897 01:04:24.489 --> 01:04:27.769 Kheench rahi hai. But the interesting thing is that we 898 01:04:27.809 --> 01:04:29.590 cannot see it directly. It is about 250 million light 899 01:04:30.230 --> 01:04:35.349 years away from us in the direction of the Centaurus constellation. 900 01:04:35.369 --> 01:04:38.329 And in that direction, there is a lot of dust 901 01:04:38.389 --> 01:04:41.190 and gas of our Milky Way which hides that area 902 01:04:41.250 --> 01:04:43.760 from our eyes. That is, the direction in which we 903 01:04:43.920 --> 01:04:46.440 are pulling, we cannot even see properly in that direction. 904 01:04:46.460 --> 01:04:56.159 This is a very strange situation. Sochiye ki aap kisi 905 01:04:56.199 --> 01:04:59.260 dhara mein hai. Paani aapko ek disha mein le jaa 906 01:04:59.300 --> 01:05:02.050 raha hai. Aur ush disha mein ek mod hai jiske 907 01:05:02.110 --> 01:05:06.090 aage kya hai, aapko nahi pata. Aap

bas beh rahe hain. 908 01:05:07.030 --> 01:05:10.750 Hamari Milky Way kuch aise hi hai. Great Attractor ki taraf. 909 01:05:11.469 --> 01:05:15.320 Lekin Great Attractor kya hai? Wo kitna massive hai? Jab 910 01:05:15.380 --> 01:05:20.400 scientists ne isse aur dhyaan se study kiya. X-ray observations se, 911 01:05:20.920 --> 01:05:25.159 infrared se, aur doosre wavelength se, which can be seen 912 01:05:25.340 --> 01:05:28.780 all over the dust. So what we got was very interesting. 913 01:05:29.599 --> 01:05:33.360 Great Attractor is a region where there are many galaxy clusters. 914 01:05:33.380 --> 01:05:38.199 The most prominent of these is Norma Cluster. It is 915 01:05:38.219 --> 01:05:43.199 a very massive galaxy cluster. And there are more clusters 916 01:05:43.260 --> 01:05:45.889 around it. But this is not the whole story. When 917 01:05:46.690 --> 01:05:49.590 more observations were made and they were seen on a 918 01:05:49.590 --> 01:05:53.510 large scale, it was found that Great Attractor khud ek 919 01:05:53.570 --> 01:05:57.110 aur bade gravitational source ki taraf khinch raha hai. Isse 920 01:05:57.130 --> 01:06:03.449 kehte hain Shapley Supercluster. Shapley Supercluster. Yeh Great Attractor se 921 01:06:03.469 --> 01:06:07.380 bhi bada hai. Yeh observable universe ke sabse massive structures 922 01:06:07.409 --> 01:06:12.159 mese ek hai. Aur yeh humse lagbhag 650 million light 923 01:06:12.199 --> 01:06:16.019 years door hai. To picture yeh hai. Hum Milky Way 924 01:06:16.039 --> 01:06:20.010 mein hain. Milky Way Great Attractor ki taraf khinch rahi hai. 925 01:06:20.960 --> 01:06:23.739 The Great Attractor is pulling itself towards the Shapley Supercluster. 926 01:06:23.760 --> 01:06:27.579 And all this is part of a very big cosmic flow. 927 01:06:27.599 --> 01:06:34.269 Scientists have given this entire flow a name. Laniakea. Laniakea. 928 01:06:34.610 --> 01:06:42.409 This is a Hawaiian word. It means Immeasurable Heaven. Laniakea 929 01:06:42.449 --> 01:06:47.460 is our supercluster. A very big supercluster. In which we 930 01:06:48.000 --> 01:06:51.519 are the Milky Way. We are our local group. Virgo 931 01:06:51.539 --> 01:06:55.000 Cluster is a great attractor. There is a lot more. 932 01:06:55.079 --> 01:06:59.719 And all this is connected together in a big gravitational basin. 933 01:06:59.739 --> 01:07:05.119 The diameter of Laniakea is about 500 million light years. 934 01:07:05.119 --> 01:07:09.260 500 million light years. This is our cosmic home. This 935 01:07:09.840 --> 01:07:13.969 is the supercluster in which we live. And there are 936 01:07:14.389 --> 01:07:18.190 more superclusters outside Laniakea. And there are more voids in 937 01:07:18.210 --> 01:07:21.949 between them. This picture is very layered. It is very complex. 938 01:07:22.010 --> 01:07:25.409 And yet it is very peaceful. Think about it. We 939 01:07:25.429 --> 01:07:28.179 are a human being. In a small city, in a 940 01:07:28.219 --> 01:07:33.119 small country, on a small earth, near an average star, 941 01:07:33.179 --> 01:07:37.920 in an average galaxy, in a galaxy group, in a supercluster, 942 01:07:38.340 --> 01:07:43.079 whose name is Laniakia. And Laniakia itself is a very 943 01:07:43.119 --> 01:07:49.489 large part of a universe. This hierarchy, these layers, The 944 01:07:49.530 --> 01:07:53.409 structure inside one. It says very quietly, where are we? 945 01:07:53.909 --> 01:07:58.030 We are very small, but we are. And this is 946 01:07:58.050 --> 01:08:02.130 the most important thing. We understand the relationship between voids 947 01:08:02.190 --> 01:08:07.849 and attractors. Because these are two aspects of the same process. 948 01:08:07.989 --> 01:08:13.949 Where matter is united, where gravity is more, there attractors 949 01:08:13.989 --> 01:08:19.479 are formed, clusters are formed, superclusters are formed. And from 950 01:08:19.520 --> 01:08:22.880 where matter pulls and goes, there are voids. That is, 951 01:08:22.880 --> 01:08:25.619 there is one void behind every attractor. And there is 952 01:08:25.640 --> 01:08:31.260 an attractor somewhere around every void. This is a balance. 953 01:08:31.640 --> 01:08:36.289 A cosmic balance. Like mountains, there are also valleys. Like light, 954 01:08:36.310 --> 01:08:38.810 there is also shade. Like day, there is also night. 955 01:08:38.829 --> 01:08:44.109 This is the same in the universe. Matter is also emptiness. 956 01:08:44.630 --> 01:08:49.069 Attractor is also void. And we Us balance ke beech 957 01:08:49.109 --> 01:08:53.680 mein hai, Milky Way Great. Attractor ki taraf khinch rahi hai. Yaani, 958 01:08:54.060 --> 01:08:56.600 hum us taraf ja rahe hain, jahan matter zyada hai. 959 01:08:57.180 --> 01:08:59.439 Aur jis taraf se hum a rahe hain, woh taraf 960 01:08:59.500 --> 01:09:03.079 shayad thodi khali hoti ja rahi hai. Yeh movement bahut 961 01:09:03.100 --> 01:09:06.979 dheemi hai. Itni dheemi ki kisi ek jeevan mein, kisi 962 01:09:07.000 --> 01:09:10.520 ek sabhyata mein, isse feel nahi kiya ja sakta. Lekin 963 01:09:10.560 --> 01:09:15.439 yeh ho rahi hai. Har pal. Abhi bhi. Isi vakt 964 01:09:15.479 --> 01:09:18.729 jab aap yeh sun rahe hain, Milky Way Great Attractor 965 01:09:18.770 --> 01:09:23.369 ki taraf ja rahi hai. Very slowly. Very quietly. This 966 01:09:23.390 --> 01:09:27.300 feeling is very light. Very calm. Like you are lying 967 01:09:27.399 --> 01:09:30.439 down at night and feel that the bed is very comfortable. 968 01:09:30.539 --> 01:09:33.140 You don't have to go anywhere. You don't have to 969 01:09:33.159 --> 01:09:35.739 do anything. You just have to stay here. We are 970 01:09:35.760 --> 01:09:38.659 in our galaxy. In our place. A small part of 971 01:09:38.699 --> 01:09:41.920 a very big flow of the universe. And that flow 972 01:09:41.960 --> 01:09:53.289 is very calm. Very old. Very big. Take a breath. Easy. 973 01:09:53.449 --> 01:09:58.289 It's night outside. The

stars are up. And we are 974 01:09:58.409 --> 01:10:01.770 a part of a very big cosmic dance on this 975 01:10:01.810 --> 01:10:07.199 small earth. That's it. Quietly. Some time ago, scientists thought 976 01:10:07.220 --> 01:10:09.920 that they had understood the big picture of the universe 977 01:10:09.939 --> 01:10:14.039 to a great extent. There are huge galaxy clusters. There 978 01:10:14.819 --> 01:10:19.050 are long filaments between them. And then there are empty 979 01:10:19.210 --> 01:10:23.340 areas between them. which we call voids. It seemed as 980 01:10:23.380 --> 01:10:27.159 if this whole structure was working in a balance. Somewhere 981 01:10:27.180 --> 01:10:32.739 the matter is more, somewhere it is very less. Somewhere 982 01:10:33.079 --> 01:10:37.189 gravity is gathering matter, somewhere it is taking it far away. 983 01:10:37.270 --> 01:10:43.510 But as our distances got better and we started looking far, 984 01:10:43.529 --> 01:10:50.029 we started getting some signs which made scientists ek naya 985 01:10:50.069 --> 01:10:54.649 prashna poochhne par majboor kar diya. Kya yeh sambhav hai 986 01:10:54.689 --> 01:10:58.090 ki hum swayam bhi kisi bahut bade void ke andar 987 01:10:58.109 --> 01:11:01.939 rahe rahe ho? Yeh vichar pehli baar sunne mein ajeeb 988 01:11:01.979 --> 01:11:05.079 lag sakta hai. Kyunki jab hum raat ke aakash ko 989 01:11:05.119 --> 01:11:09.859 dekhte hai, to hume asankhya taare dikhaai dete hai. Humari 990 01:11:09.920 --> 01:11:14.100 Milky Way Galaxy arbon taaron se bharhi hui hai. Uske 991 01:11:14.140 --> 01:11:18.739 aas paas bhi anek galaxies maujood hai. Aise mein, How 992 01:11:18.819 --> 01:11:21.720 can it be said that we are in an empty space? 993 01:11:21.739 --> 01:11:24.760 The answer to this question is hidden in the scale. 994 01:11:24.779 --> 01:11:28.640 When scientists talk about a void, they are not talking 995 01:11:29.199 --> 01:11:32.100 about a solar system or a galaxy, but about the 996 01:11:32.779 --> 01:11:36.289 ratio of billions and billions of light years. In an area, 997 01:11:36.310 --> 01:11:39.729 there can be many galaxies at a local level. But 998 01:11:39.750 --> 01:11:42.170 if we look at a larger ratio, then that area 999 01:11:42.250 --> 01:11:49.930 is can be less dense than the average of the universe. 1000 01:11:49.949 --> 01:11:54.689 This thought is associated with a proposed field, which is 1001 01:11:54.710 --> 01:11:59.270 called KBC Void. The name KBC has been taken from 1002 01:11:59.289 --> 01:12:05.189 the names of those scientists who had studied this possibility. 1003 01:12:05.229 --> 01:12:09.029 Their suggestion was that perhaps our local universe can be 1004 01:12:09.050 --> 01:12:12.539 located in a large, less dense field. If this is true, 1005 01:12:13.260 --> 01:12:17.569 then its size can be from hundreds of millions Lakhbhag 1006 01:12:17.569 --> 01:12:21.180 2 billion prakash varsh tak ho sakta hai. Ye itna 1007 01:12:21.189 --> 01:12:24.119 bada kshetra hoga ki, hamari kalpna se bhi pare hai. 1008 01:12:24.960 --> 01:12:27.560 Mahatwa poon baat ye hai ki, yeh poon khali pan 1009 01:12:27.579 --> 01:12:31.460 nahi hoga. Jaisa ki humne pehle bhi dekha hai, koi 1010 01:12:31.500 --> 01:12:36.060 bhi jhaat void, puri tarah khali nahi hota. Uske andar 1011 01:12:36.119 --> 01:12:40.449 galaxies maujood rehti hai, bas unki sankhya samanya kshetron ki 1012 01:12:40.470 --> 01:12:44.350 tulna me kam hoti hai. KBC void ka vichar bhi 1013 01:12:44.390 --> 01:12:49.229 kuch aisa hi hai. Hamari Milky Way, Andromeda, Local Group, 1014 01:12:49.609 --> 01:12:53.250 and Laniakia. But in total, this entire area can be 1015 01:12:53.350 --> 01:12:58.670 a little less material than the universe. Now the question is, 1016 01:12:58.850 --> 01:13:03.640 why did scientists start thinking like this? Its answer takes 1017 01:13:03.689 --> 01:13:08.039 us to one of the most interesting mysteries of modern cosmology. 1018 01:13:08.060 --> 01:13:11.600 It is called Hubble Tension. The universe is constantly spreading. 1019 01:13:17.770 --> 01:13:21.909 This fact is about a century old. But when scientists 1020 01:13:21.989 --> 01:13:26.939 measure the extent of this expansion, they get two different answers. 1021 01:13:27.539 --> 01:13:31.180 The first way is to see the very distant primitive universe. 1022 01:13:31.960 --> 01:13:35.220 Cosmic Microwave Background gives us a picture of that time 1023 01:13:35.239 --> 01:13:39.600 when the universe was very young. Using that information, scientists 1024 01:13:39.979 --> 01:13:44.029 calculate the extent of the expansion today. The second way 1025 01:13:44.050 --> 01:13:51.949 is Apekshakrit Paas ki Galaxies ko dekh kar vartmaan Vistardhar 1026 01:13:52.010 --> 01:13:56.550 ko seedhe maapna. Samasya ye hai ki dono parinaam ek 1027 01:13:56.609 --> 01:14:00.649 dusre se puri tarah mel nahi khaate. Dono ke beech 1028 01:14:01.149 --> 01:14:04.640 ek antar dikhaai deta hai. Yeh antar bahut bada nahi hai. 1029 01:14:05.340 --> 01:14:09.520 Lekin itna avashya hai ki vaigyanik usse keval measurement error 1030 01:14:09.560 --> 01:14:14.199 kahe kar nazrandaaz nahi kar sakte. Yehi Hubble tension hai. 1031 01:14:14.220 --> 01:14:18.630 Aur yahi par KBC Void ka vichar phir saamne aata hai. 1032 01:14:19.569 --> 01:14:23.050 Kuch vaigyanikon ne sujhav diya ki yadi hum vaastav mein 1033 01:14:23.489 --> 01:14:26.890 ek kam ghanatwa wale kshetra ke andar sthit hain, to 1034 01:14:26.930 --> 01:14:30.270 sambhav hai ki hamari local measurements prabhavit ho rahi ho. 1035 01:14:31.170 --> 01:14:34.430 Kalpana kijiye ki aap kisi pahadi ghaati mein khade hain 1036 01:14:34.909 --> 01:14:38.789 aur mausam ka anuman laga rahe hain. Aapke aas paas 1037 01:14:38.810 --> 01:14:43.449 ka vataavaran poore grahe ke ausat vataavaran se thoda alag 1038 01:14:43.470 --> 01:14:47.159 ho sakta hai. Isi prakaar, If our place is different 1039 01:14:47.220 --> 01:14:50.079 from

the average of the universe, then it is possible 1040 01:14:50.100 --> 01:14:53.500 that our local measurements of expansion may also look a 1041 01:14:53.520 --> 01:14:57.979 little different. This thought created a lot of interest. But 1042 01:14:58.100 --> 01:15:02.550 in science, only attractive thoughts are not enough. They need evidence. 1043 01:15:02.609 --> 01:15:06.710 Many researches were done in the next few years. Various 1044 01:15:06.789 --> 01:15:14.970 surveys measured the distribution of galaxies in more detail. Scientists 1045 01:15:14.979 --> 01:15:17.770 have tried to understand how much of the material around 1046 01:15:17.810 --> 01:15:22.770 us is actually density. Some results have supported this possibility 1047 01:15:22.789 --> 01:15:26.489 that our area can be slightly less density than the atmosphere. 1048 01:15:26.909 --> 01:15:31.680 Other results have indicated that this effect is not enough 1049 01:15:31.720 --> 01:15:35.020 to fully explain the Hubble tension. Even today, this issue 1050 01:15:35.079 --> 01:15:44.329 has not completely ended. Some scientists believe that local under-density 1051 01:15:44.390 --> 01:15:48.630 can be present. Some believe that its effect will be 1052 01:15:48.649 --> 01:15:52.220 very limited. Others believe that the real reason for the 1053 01:15:52.300 --> 01:15:57.180 Hubble tension can be hidden in some other deep physical principle. 1054 01:15:57.199 --> 01:16:01.300 This is the beauty of science. Sometimes, an attempt to 1055 01:16:01.340 --> 01:16:04.520 answer a question leads us to even bigger questions. If 1056 01:16:04.539 --> 01:16:12.079 we are actually in some huge void, to iska aarth 1057 01:16:12.159 --> 01:16:15.819 keval itna nahi hoga ki hamare aas paas padarth kam hai. 1058 01:16:16.720 --> 01:16:19.779 Iska aarth yeh bhi hoga ki, brahmand ke baare mein 1059 01:16:19.840 --> 01:16:24.670 hamari drishti kuch had tak sthaniye paristhitiyon se prabhavit hai. 1060 01:16:25.630 --> 01:16:29.310 Ham aksar ya maan lete hain ki, hamara sthan samanya hai. 1061 01:16:30.050 --> 01:16:34.430 Lekin kya vastav mein aisa hai? Cosmological principle kehta hai ki, 1062 01:16:34.550 --> 01:16:39.199 bahut bade paimane par, brahmand har disha mein lagbhag saman hai. 1063 01:16:40.020 --> 01:16:42.460 This is the basis of modern cosmology. Still, there are 1064 01:16:43.100 --> 01:16:50.220 inequalities at the local level. There are galaxies, clusters, superclusters 1065 01:16:50.619 --> 01:16:53.409 and voids. That's why we think that we can be 1066 01:16:53.729 --> 01:16:56.989 in a big under-dense region. It's not entirely impossible. Although 1067 01:16:57.010 --> 01:17:02.609 we haven't yet found any definitive evidence that proves this possibility. Still, 1068 01:17:02.630 --> 01:17:12.000 this question is being asked. And sometimes, questions are more 1069 01:17:12.020 --> 01:17:16.640 interesting than answers. When we look at the sky at night, 1070 01:17:16.659 --> 01:17:20.880 we feel that we are in a normal corner of 1071 01:17:20.899 --> 01:17:24.100 the universe. But it is possible that our cosmic address 1072 01:17:24.119 --> 01:17:27.310 is much more special than our imagination. Perhaps we are 1073 01:17:27.319 --> 01:17:32.109 inside a vast, empty space. Perhaps not. For now, science 1074 01:17:32.949 --> 01:17:38.369 keeps both possibilities open. And until we become better aware, 1075 01:17:39.989 --> 01:17:45.100 Yeh rahasya bana rahega. Dheere dheere, jaise hamari door beene 1076 01:17:45.109 --> 01:17:48.640 aur adhik door tak dekhne lagengi, hum iss prashna ka 1077 01:17:48.739 --> 01:17:53.340 uttar khojne ki koshish karte rahenge. Lekin iss khoj ke dauraan, 1078 01:17:53.899 --> 01:17:57.359 ek aur vichar saamne aata hai. Yadhi hum apne aas 1079 01:17:57.399 --> 01:18:01.239 paas ke kshetra ki seemaon ko samajhna chahte hain, to 1080 01:18:01.279 --> 01:18:05.659 hume yeh bhi samajhna hoga, ki poore observable universe ki 1081 01:18:05.699 --> 01:18:09.449 seemaen kya hain. Aakhir koi void kitna bada ho sakta hai? 1082 01:18:10.270 --> 01:18:13.729 Kya uske aakar ki koi antim seema hai? Aur kya 1083 01:18:14.149 --> 01:18:17.770 brahmand ke niyam kisi void ko anant hone se rogtay hain? 1084 01:18:18.710 --> 01:18:22.060 Yahi prashna hume aage usse seema tak le jaayega jahan 1085 01:18:22.479 --> 01:18:26.279 hamari drishti swayam samaapt ho jaati hai. Aur jahan se 1086 01:18:26.720 --> 01:18:30.539 observable universe ki kahani shuru hoti hai. Aapki drishti jahan 1087 01:18:30.560 --> 01:18:34.880 tak pohch sakti hai, brahmand usse bhi kahin adhik vishal hai. 1088 01:18:36.020 --> 01:18:39.550 KBC void ke baare mein sochte hua, Hum iss sambhavana 1089 01:18:39.569 --> 01:18:43.899 tak pohche the ki shayad hamara apna kshetra bhi poori 1090 01:18:43.939 --> 01:18:48.689 tarah samanya nahi hai. Lekin chahe hum kisi underdense region 1091 01:18:48.710 --> 01:18:43.069 mein ho ya nahi. that maybe our own field is 1092 01:18:43.670 --> 01:18:47.680 also not completely normal. But whether we are in an 1093 01:18:47.800 --> 01:18:53.619 under-dense region or not, one thing is certain. We cannot 1094 01:18:53.680 --> 01:18:58.079 see the universe completely. We can only see a small 1095 01:18:58.140 --> 01:19:01.890 part of it. This part is called the observable universe. 1096 01:19:02.149 --> 01:19:04.949 This word sounds simple, but there is a deep truth 1097 01:19:04.970 --> 01:19:12.329 hidden behind it. When we look at a distant galaxy, 1098 01:19:12.430 --> 01:19:17.689 we are not looking at the present. We are looking 1099 01:19:17.710 --> 01:19:21.170 at its past. Because it takes time for light to travel. 1100 01:19:21.210 --> 01:19:24.289 If a galaxy is 10 million light years away from us, 1101 01:19:24.609 --> 01:19:27.689 its light takes 10 million years to reach us. This 1102 01:19:27.729 --> 01:19:29.659 means that we are looking at it as if it 1103 01:19:29.699 --> 01:19:40.329 was 10

million years ago. The farther we look, utna 1104 01:19:40.369 --> 01:19:43.739 hi adhik ateet mein jaakte hain. Aur ek bindu aisa 1105 01:19:43.760 --> 01:19:47.159 aata hai, jahaan hum brahmand ke shuruwati samay tak pahuch 1106 01:19:47.180 --> 01:19:50.880 jaate hain. Usse aage dekhna sambhav nahi hai, kyunki uss 1107 01:19:50.920 --> 01:19:55.430 samay brahmand prakaash ke liye paardarshi nahi tha. Yahi hamari 1108 01:19:55.449 --> 01:19:59.170 drishya seema hai. Yeh koi diwaar nahi hai. Yeh koi 1109 01:19:59.529 --> 01:20:04.069 kinara nahi hai. Balki, yeh wah seema hai, jahaan tak 1110 01:20:04.189 --> 01:20:08.359 jaankari hum tak pahuch sakhi hai. Aaj ke vaigyanik anuman 1111 01:20:08.380 --> 01:20:13.560 ke anusaar, Observable, universe ka vyas lagbhag 93 billion prakash 1112 01:20:13.600 --> 01:20:18.180 varsh hai. Yeh sankhya itni vishal hai ki maanav mastisk 1113 01:20:18.220 --> 01:20:22.680 ke liye iski kalpna karna lagbhag asambhav hai. Lekin issse 1114 01:20:22.699 --> 01:20:26.149 bhi adhik rochak baat yeh hai ki poora brahmand shayad 1115 01:20:26.250 --> 01:20:30.550 issse kahin bada ho. Sambhav hai ki observable universe kewal 1116 01:20:30.569 --> 01:20:34.529 ek chota sa hissa ho. Theek vaise hi jaise samudra 1117 01:20:34.569 --> 01:20:38.489 kinare khada vyakti kshitij tak hi dekh sakta hai. but 1118 01:20:38.520 --> 01:20:43.460 the ocean spreads far beyond it. Our cosmic horizon is 1119 01:20:43.920 --> 01:20:50.079 also something like this. What we can see is only 1120 01:20:50.100 --> 01:20:54.699 the limit of our vision. Not the real limit of 1121 01:20:54.760 --> 01:20:57.920 the universe. And this leads us to a new question. 1122 01:20:58.000 --> 01:21:00.600 If the universe is so huge, then how big can 1123 01:21:00.619 --> 01:21:03.720 a void be? Can a void be so big that 1124 01:21:03.739 --> 01:21:09.069 it is equal to the observable universe? Or do the 1125 01:21:09.109 --> 01:21:12.789 laws of nature limit it? To find the answer to 1126 01:21:12.829 --> 01:21:16.430 this question, we have to understand how voids are formed. 1127 01:21:16.470 --> 01:21:20.899 As we saw earlier, voids do not appear suddenly. The 1128 01:21:20.909 --> 01:21:25.979 matter in the initial universe was not completely evenly distributed. 1129 01:21:26.020 --> 01:21:32.500 Somewhere the density was a little more, somewhere a little less. 1130 01:21:32.560 --> 01:21:38.390 Over time, gravity made the areas with more density even thicker. Wherein, 1131 01:21:38.409 --> 01:21:43.300 the less densely populated areas became more empty. This process, 1132 01:21:43.319 --> 01:21:45.659 which lasted for billions of years, gave birth to the 1133 01:21:46.119 --> 01:21:50.260 cosmic web. But this process also has its limits. If 1134 01:21:50.899 --> 01:21:52.800 there is very little matter in an area, then it 1135 01:21:52.859 --> 01:21:59.050 cannot completely disappear. Some amount of matter and dark matter 1136 01:21:59.359 --> 01:22:04.069

will remain there. For this reason, scientists have not yet 1137 01:22:04.090 --> 01:22:08.649 found a void that is completely empty. Har jhaat void 1138 01:22:08.670 --> 01:22:12.550 ke beater kuch galaxies avashya maujood hain. Yehi kaaran hai 1139 01:22:12.569 --> 01:22:16.069 ki cosmological models yeh sujhav dete hain ki void ka 1140 01:22:16.090 --> 01:22:20.689 aakaar anant nahi ho sakta. Jaisa jaisa void bada hota hai, 1141 01:22:21.189 --> 01:22:25.380 uske aas paas ke kshetron ka prabhaav bhi badta hai. Gravity, 1142 01:22:25.840 --> 01:22:31.460 expansion aur matter distribution mil kar ek santulan banate hain. Isliye, 1143 01:22:31.859 --> 01:22:35.619 atyadhik vishal void banna kathin ho jaata hai. Phir bhi 1144 01:22:35.659 --> 01:22:38.850 brahmand hume baar baar chonk aata hai. When the Boötes 1145 01:22:38.880 --> 01:22:45.140 Void was discovered, its shape was unbelievable. Later, Eridanus Super 1146 01:22:45.180 --> 01:22:47.939 Void was found, which was even bigger than that. Then 1147 01:22:48.020 --> 01:22:52.180 other huge structures came to light. Every new discovery reminds 1148 01:22:52.239 --> 01:22:57.159 us that our knowledge is still incomplete. It is possible 1149 01:22:57.180 --> 01:23:00.220 that we may find even bigger voids in the future. 1150 01:23:00.239 --> 01:23:02.260 But if a void is too big, it can be 1151 01:23:02.340 --> 01:23:10.289 a challenge for cosmological principles. Cosmological principle is an important 1152 01:23:10.350 --> 01:23:12.850 basis of modern cosmology. It says that on a very 1153 01:23:12.869 --> 01:23:16.850 large scale, the universe is almost equal in every direction. 1154 01:23:16.890 --> 01:23:20.050 If there is a very large empty space somewhere, then 1155 01:23:20.069 --> 01:23:23.289 this equality can be affected. That is why scientists study 1156 01:23:23.310 --> 01:23:27.270 big voids very carefully. They are not just studying empty spaces. 1157 01:23:36.880 --> 01:23:41.810 They are investigating the rules of the entire universe. Sometimes 1158 01:23:41.819 --> 01:23:47.430 it seems that voids are just non-existent. Like nothing is there. 1159 01:23:47.829 --> 01:23:52.250 That's why there is nothing to see there. But reality 1160 01:23:52.369 --> 01:23:56.720 is contrary to this. Voids tell us where matter is not. 1161 01:23:56.760 --> 01:24:01.699 And this information is as important as knowing where matter 1162 01:24:01.819 --> 01:24:07.149 is present. If you want to understand a picture, then 1163 01:24:07.189 --> 01:24:10.739 just looking at colours is not enough. Empty space is 1164 01:24:10.760 --> 01:24:14.579 equally important. In the same way, the cosmic web has 1165 01:24:14.619 --> 01:24:17.720 the colours of galaxies and voids are the empty space 1166 01:24:17.779 --> 01:24:21.989 between them. Both together make the whole picture. Going near 1167 01:24:22.010 --> 01:24:25.710 the limit of the observable universe, this thought becomes even 1168 01:24:25.750 --> 01:24:29.989 more interesting. We can only measure that area which we 1169 01:24:30.369 --> 01:24:37.479 can see. But if our vision is If there are 1170 01:24:37.520 --> 01:24:40.000 even more vast voids outside, then it is possible. It 1171 01:24:40.079 --> 01:24:43.319 is possible that there are areas beyond our reach that 1172 01:24:43.350 --> 01:24:46.550 are not visible from any telescope of today. It is 1173 01:24:46.590 --> 01:24:49.949 possible that the distribution of matter there is different from ours. 1174 01:24:49.970 --> 01:24:53.949 It is possible that there are structures there which we 1175 01:24:53.989 --> 01:24:57.310 have not even imagined. And it is also possible that 1176 01:24:57.329 --> 01:25:01.310 there is nothing extraordinary there. For now, we don't know. 1177 01:25:01.329 --> 01:25:07.050 But in science, we don't know. is a very important statement. 1178 01:25:07.930 --> 01:25:13.729 This statement gives birth to new discoveries. This statement is 1179 01:25:13.770 --> 01:25:16.970 the reason for the creation of new probes. This statement 1180 01:25:16.989 --> 01:25:21.970 inspires scientists to study data until night. Because there is 1181 01:25:22.069 --> 01:25:26.720 another question hidden behind every answer. When we think about 1182 01:25:26.729 --> 01:25:31.500 the limit of the observable universe, we have a strange feeling. 1183 01:25:35.250 --> 01:25:38.829 Manav Sabyata has made a lot of progress. We studied planets, 1184 01:25:39.130 --> 01:25:44.229 understood stars, measured galaxies, took pictures of black holes. Still, 1185 01:25:44.270 --> 01:25:47.369 we are only able to see a small part of 1186 01:25:47.390 --> 01:25:51.409 the entire universe. All our knowledge comes from a limited window. 1187 01:25:51.449 --> 01:25:55.229 What is outside that window? It is still a mystery. 1188 01:25:55.310 --> 01:26:00.229 And perhaps this mystery makes the universe so attractive. Thinking 1189 01:26:00.250 --> 01:26:07.439 about voids, we reach such a limit where our ability 1190 01:26:07.930 --> 01:26:11.289 to see ends. But our curiosity does not end. Because 1191 01:26:11.310 --> 01:26:14.670 where our eyes stop, our imagination moves forward. And in 1192 01:26:14.710 --> 01:26:19.270 this journey, another important question is waiting for us. If 1193 01:26:19.289 --> 01:26:23.069 galaxies and stars are made of ordinary matter, then where 1194 01:26:23.090 --> 01:26:36.590 is dark matter inside those huge voids? void se door 1195 01:26:36.609 --> 01:26:41.029 chala jaata hai? Ya phir, waha unkhali kshetro mein kisi 1196 01:26:41.470 --> 01:26:45.829 adrishya jaal ki tara ab bhi maujood rehta hai? Is 1197 01:26:45.930 --> 01:26:50.069 prashna ka uttar, hume brahmand ke sabse rahasyamay padartho mein 1198 01:26:50.109 --> 01:26:53.880 se ek ki aur le jaayega. Dark matter ki aur. 1199 01:26:54.380 --> 01:26:58.699 Dark matter ki aur. Yeh naam sunne mein jitna rahasyamay 1200 01:26:58.720 --> 01:27:03.340

lagta hai, vastavikta usse bhi adhik rochak hai. Kyunki dark 1201 01:27:03.399 --> 01:27:06.670 matter aisi cheez hai, which we have never seen directly. 1202 01:27:06.710 --> 01:27:12.109 We have not taken any picture of it. No telescope 1203 01:27:12.149 --> 01:27:15.029 has ever seen it shining. It neither makes light attractive, 1204 01:27:15.050 --> 01:27:17.609 nor changes it, nor does it contact it in a 1205 01:27:18.109 --> 01:27:21.619 normal way. Still, scientists have full faith that it is present. 1206 01:27:21.840 --> 01:27:26.319 The reason is that there are many such incidents in 1207 01:27:26.340 --> 01:27:35.850 the universe, which are only Samanya matter se samjhaya nahin 1208 01:27:35.869 --> 01:27:39.810 ja sakta. Jab vaigyanik galaxies ki gati ko maapte hai, 1209 01:27:40.350 --> 01:27:43.500 toh unhe pata chalta hai ki ve jitni tezi se 1210 01:27:43.520 --> 01:27:47.159 ghoom rahi hai, utni gati par unhe toot kar bikhar 1211 01:27:47.199 --> 01:27:52.479 jaana chahiye. Lekin aisa nahin hota. Kuch atirikt gravity unhe 1212 01:27:52.680 --> 01:27:56.840 ek saath baandhe rakti hai. Yahi atirikt gravity dark matter 1213 01:27:56.880 --> 01:28:00.899 ki aur sanket karti hai. Aaj ke anuman ke anusaar, 1214 01:28:01.260 --> 01:28:09.239 brahmand ka adhikansh matter vahee hai. which we cannot see. Stars, planets, gas, dust, 1215 01:28:09.319 --> 01:28:14.560 and we ourselves are just a small part of the universe. 1216 01:28:14.600 --> 01:28:18.619 The rest is dark matter. And this makes voids even 1217 01:28:18.640 --> 01:28:22.750 more interesting. When we look at a void, we see 1218 01:28:23.170 --> 01:28:27.390 that there are very few galaxies, very few stars, and 1219 01:28:27.430 --> 01:28:31.569 very few gases. But does this mean that there is 1220 01:28:31.750 --> 01:28:35.550 no dark matter there? The answer to this question is 1221 01:28:35.569 --> 01:28:40.479 not completely simple. In the beginning, scientists thought that if 1222 01:28:40.579 --> 01:28:42.899 there are few galaxies in an area, then there should 1223 01:28:42.920 --> 01:28:46.760 be very little dark matter there. Because the development of 1224 01:28:47.199 --> 01:28:51.760 galaxies and dark matter is considered to be connected to 1225 01:28:52.699 --> 01:28:54.979 each other. But as the simulations got better, the picture 1226 01:28:55.000 --> 01:29:00.770 became a little more complicated. Today we know that voids 1227 01:29:01.050 --> 01:29:06.470 are not completely empty. And possibly, dark matter also does 1228 01:29:06.489 --> 01:29:12.520 not disappear completely from them. Rather, it seems that dark 1229 01:29:12.579 --> 01:29:15.659 matter also exists within voids. But its density is very 1230 01:29:15.680 --> 01:29:19.380 less than that of normal areas. To understand this, imagine 1231 01:29:19.399 --> 01:29:23.439 a calm sea. Somewhere in the sea, there are big waves. 1232 01:29:23.479 --> 01:29:29.430 Somewhere small. And somewhere the water is

unexpectedly calm. This 1233 01:29:30.170 --> 01:29:33.529 does not mean that there is no water there. Only 1234 01:29:33.869 --> 01:29:38.899 its distribution is different. Something similar can also happen with 1235 01:29:38.939 --> 01:29:44.039 dark matter. Galaxy clusters and filaments are such areas where 1236 01:29:44.100 --> 01:29:48.840 dark matter has gathered in excess. Whereas voids are such 1237 01:29:48.960 --> 01:29:52.420 areas where its density has remained very low. But the 1238 01:29:53.420 --> 01:29:57.539 meaning of low density is not zero density. This is 1239 01:29:57.560 --> 01:30:01.739 the reason why scientists sometimes call voids the expanse of 1240 01:30:01.779 --> 01:30:06.149 the universe. Because if there is very little normal matter 1241 01:30:06.159 --> 01:30:09.210 in an area, then the effects of dark matter and 1242 01:30:09.270 --> 01:30:12.250 dark energy can be understood more clearly. In a way, 1243 01:30:12.310 --> 01:30:16.470 voids are the most peaceful areas of the universe. And 1244 01:30:16.569 --> 01:30:18.770 in peace, we often see things that hide in noise. 1245 01:30:25.560 --> 01:30:31.850 When we study a huge galaxy cluster, then countless processes 1246 01:30:31.970 --> 01:30:37.869 are going on there. Stars are forming, supernova explosions are happening, 1247 01:30:38.470 --> 01:30:43.739 black holes are forming, gas clouds are colliding. But in voids, 1248 01:30:43.819 --> 01:30:48.260 this is very rare. There is unexpected silence. And this 1249 01:30:48.279 --> 01:30:52.189 silence allows scientists to understand the basic rules of the universe. 1250 01:30:55.189 --> 01:31:00.210 Some simulations suggest that even inside voids, dark matter can 1251 01:31:00.229 --> 01:31:02.189 spread like a thin net. It can be so weak 1252 01:31:02.250 --> 01:31:05.470 and virile that it is almost impossible to see it 1253 01:31:05.510 --> 01:31:10.000 directly from the current instrument. But its gravity still remains present. 1254 01:31:10.020 --> 01:31:16.279 Although it is very weak in comparison to gravity clusters. 1255 01:31:16.319 --> 01:31:19.600 This is the reason why the number of galaxies inside 1256 01:31:19.640 --> 01:31:27.140 voids is very low. Because there is not enough matter 1257 01:31:27.159 --> 01:31:30.399 present there which can increase the creation of galaxies in 1258 01:31:30.470 --> 01:31:35.289 a large number. Still, the whole story is not that simple. 1259 01:31:35.329 --> 01:31:39.989 Many times scientists have searched for such galaxies in voids 1260 01:31:40.449 --> 01:31:44.689 whose presence is surprising. When an area is considered to 1261 01:31:44.869 --> 01:31:49.250 be extremely empty and then a galaxy is found there, 1262 01:31:49.789 --> 01:31:54.050 then it becomes an important sign. Because that galaxy is 1263 01:31:54.479 --> 01:31:56.439 It tells us something about the history of that area. 1264 01:31:56.520 --> 01:31:58.699 It tells us that there must have been

a matter there. 1265 01:31:58.800 --> 01:32:02.210 It tells us that the whole emptiness is perhaps nowhere 1266 01:32:02.250 --> 01:32:05.810 in nature. This thought may sound philosophical, but from a 1267 01:32:05.810 --> 01:32:10.029 scientific point of view, it is quite interesting. Wherever we 1268 01:32:10.609 --> 01:32:13.989 see in the universe, we see some kind of structure. 1269 01:32:14.890 --> 01:32:17.680 Even in the most empty area, something or the other exists. 1270 01:32:25.140 --> 01:32:28.300 Sabse vishal void mein bhi kuch galaxies mil jaati hain. 1271 01:32:29.239 --> 01:32:32.779 Sabse andherik shetra mein bhi gravity apna prabhaav chhodti hai. 1272 01:32:33.539 --> 01:32:38.050 Maano prakriti poon shunyata ko swikar hi nahi karti. Aur 1273 01:32:38.100 --> 01:32:42.329 shayad yahi kaaran hai ki dark matter ka adhyayan itna 1274 01:32:42.369 --> 01:32:46.390 mehtv poon hai. Kyunki yeh hame keval yeh nahi batata 1275 01:32:46.430 --> 01:32:50.170 ki brahmand mein kya hai. Yeh hame yeh bhi batata 1276 01:32:50.189 --> 01:32:54.369 hai ki jo dikhai nahi deta. Wah kitna mehtv poon 1277 01:32:54.390 --> 01:32:57.640 ho sakta hai. Our eyes only see stars, but the 1278 01:32:58.180 --> 01:33:03.640 speed of galaxies feels dark matter. We see light through telescopes, 1279 01:33:03.659 --> 01:33:08.340 but gravity finds those invisible structures that are hidden from light. 1280 01:33:08.800 --> 01:33:12.979 Sometimes it seems that the entire cosmic web is actually 1281 01:33:13.119 --> 01:33:16.600 made on the invisible surface of dark matter. Like a 1282 01:33:16.939 --> 01:33:26.489 building's roof is hidden behind walls. but it supports the 1283 01:33:26.609 --> 01:33:32.100 entire structure. Similarly, dark matter can be the hidden structure 1284 01:33:32.180 --> 01:33:37.100 of the universe. Galaxies and stars are only its visible part. 1285 01:33:37.840 --> 01:33:40.760 And if this thought is right, then voids are not 1286 01:33:41.060 --> 01:33:44.479 just an empty area. They are part of that huge 1287 01:33:44.500 --> 01:33:48.369 invisible net that is spread throughout the universe. That's why 1288 01:33:49.130 --> 01:33:55.329 scientists are constantly making better surveys and simulations. They want 1289 01:33:55.350 --> 01:33:59.619 to understand how the real distribution of dark matter inside 1290 01:33:59.640 --> 01:34:03.180 voids is. Is it spread evenly? Is it present in 1291 01:34:03.680 --> 01:34:08.199 the form of thin filaments? Are some voids actually more 1292 01:34:08.220 --> 01:34:11.840 empty than others? The answers to these questions are still 1293 01:34:11.859 --> 01:34:15.569 not completely clear. But every new evolution takes us a 1294 01:34:15.590 --> 01:34:21.050 little closer. And perhaps the future distance will remove some 1295 01:34:21.069 --> 01:34:26.500 more layers of this mystery. For now, it is so 1296 01:34:26.539 --> 01:34:30.760 clear that voids are not just a story of non-existence. 1297

01:34:30.800 --> 01:34:34.010 They are also a story of hidden existence. There are 1298 01:34:34.130 --> 01:34:39.750 few stars, few galaxies, few matter. But physics is still 1299 01:34:39.770 --> 01:34:44.270 working there. Gravity is still present. Dark matter is still 1300 01:34:44.310 --> 01:34:48.819 leaving its effect. And dark energy is still trying to 1301 01:34:48.840 --> 01:34:51.300 spread the space. In between all this, voids are slowly 1302 01:34:51.319 --> 01:34:57.029 growing bigger and bigger. This process has been going on 1303 01:34:57.050 --> 01:35:00.630 for billions of years. And it will continue for billions 1304 01:35:00.670 --> 01:35:04.600 of years to come. With time, galaxies will move further 1305 01:35:04.689 --> 01:35:09.619 away from each other. Filaments will appear thinner. Empty regions 1306 01:35:10.000 --> 01:35:14.199 will become even larger. Gradually, the image of the universe 1307 01:35:14.239 --> 01:35:18.300 will change. There will come a time when voids will 1308 01:35:18.340 --> 01:35:21.760 not only remain a part of the universe. They will 1309 01:35:21.779 --> 01:35:26.760 become its most important specialty. And then how will the 1310 01:35:26.779 --> 01:35:31.050 universe look? This imagination takes us to its farthest future journey. 1311 01:35:31.090 --> 01:35:33.850 To a future where voids will rule and where vast 1312 01:35:33.909 --> 01:35:36.590 emptiness will spread over the majority of the universe. To 1313 01:35:36.670 --> 01:35:41.109 a future where voids will rule and where vast emptiness 1314 01:35:41.140 --> 01:35:53.020 will spread over the majority of the universe. When we 1315 01:35:53.039 --> 01:35:56.479 look at the sky at night, we see stars. We 1316 01:35:56.520 --> 01:36:00.760 see galaxies. We feel that the universe is filled with 1317 01:36:00.859 --> 01:36:04.020 light and structure in every direction. But this view will 1318 01:36:04.060 --> 01:36:07.939 not always be like this. The universe is constantly changing. 1319 01:36:07.960 --> 01:36:11.810 This change is so slow that it is almost impossible 1320 01:36:11.819 --> 01:36:18.310 to feel it on the scale of human life. But 1321 01:36:18.439 --> 01:36:24.239 over billions of years, this change becomes huge. Even today, 1322 01:36:24.279 --> 01:36:28.300 galaxies are moving away from each other. Dark energy is 1323 01:36:28.319 --> 01:36:32.579 continuously increasing the space of space. And because of this expansion, 1324 01:36:32.939 --> 01:36:35.060 voids are gradually increasing. When a void is big, it 1325 01:36:35.079 --> 01:36:39.119 is not actually swallowing anything. Rather, the matter around it 1326 01:36:39.159 --> 01:36:50.329 is slowly moving away from it. galaxies, filaments and clusters, 1327 01:36:50.390 --> 01:36:57.390 whereas empty areas become more and more empty. This process 1328 01:36:57.470 --> 01:37:00.630 has been going on for billions of years and will 1329 01:37:00.670 --> 01:37:05.350 continue

in the future. Imagine that you are in a 1330 01:37:05.350 --> 01:37:10.590 very distant future. So far that today's Earth, today's solar 1331 01:37:10.609 --> 01:37:14.720 system and perhaps our present Milky Way have become a 1332 01:37:14.760 --> 01:37:17.689 part of history. At that time, the view of the 1333 01:37:17.710 --> 01:37:20.829 universe will not be like today. The distances between galaxies 1334 01:37:20.869 --> 01:37:23.210 will have increased a lot. Today we can see millions 1335 01:37:23.270 --> 01:37:26.260 of galaxies. But in the near future, most galaxies will 1336 01:37:26.270 --> 01:37:28.319 have gone out of our sight. Their light will never 1337 01:37:28.340 --> 01:37:30.699 reach us. Because the expansion of space will be more 1338 01:37:30.779 --> 01:37:46.649 influential than the journey of light. dheere dheere door sthit 1339 01:37:46.689 --> 01:37:51.029 galaxies cosmic horizon ke paar chali jayengi. Ve nasht nahi hongi, 1340 01:37:51.449 --> 01:37:55.739 ve bas hamari pohch se bahar ho jayengi. Ek bhavishya 1341 01:37:55.760 --> 01:37:59.439 ka Khagol Shastri shayad keval apni local galaxy group ko 1342 01:37:59.479 --> 01:38:02.439 hi dekh sakhe. Usse yah bhi pata na ho ki 1343 01:38:02.479 --> 01:38:08.090 kabhi Brahmand me asankhya galaxies maujood thi. Uski drishti me 1344 01:38:08.149 --> 01:38:12.630 Brahmand bahut chota aur adik akela dikhayi de sakta hai. 1345 01:38:13.489 --> 01:38:16.899 Aur isi dauraan, Voids will become even bigger. The areas 1346 01:38:16.920 --> 01:38:19.899 that have grown hundreds of millions of light years today, 1347 01:38:19.920 --> 01:38:22.640 they can spread even more in the future. The distance 1348 01:38:22.659 --> 01:38:27.710 between filaments will increase. Clusters will be further apart from 1349 01:38:27.729 --> 01:38:31.439 each other. Only the areas of of empty areas will increase. 1350 01:38:31.460 --> 01:38:36.079 Imagine that the universe is slowly changing into a huge, 1351 01:38:36.140 --> 01:38:39.920 peaceful ocean, where sometimes only a few dweebs are visible. 1352 01:38:39.939 --> 01:38:44.210 Like these dweebs, galaxies will remain. But their emptiness will 1353 01:38:44.229 --> 01:38:49.739 be much larger than before. Scientists This possible future is 1354 01:38:49.800 --> 01:38:55.319 sometimes called a void-dominated universe. That is, a universe where 1355 01:38:55.640 --> 01:39:00.180 the most important thing is not galaxies, but voids. This 1356 01:39:01.039 --> 01:39:04.319 may sound a little sad to hear, but for nature, 1357 01:39:04.350 --> 01:39:08.890 this is just a normal direction of development. The universe 1358 01:39:09.890 --> 01:39:14.350 is not moving towards any goal. It is just following 1359 01:39:14.369 --> 01:39:20.789 its own rules. Gravity Dark matter and dark energy are 1360 01:39:20.810 --> 01:39:24.010 having their own effects. And the result of these effects 1361 01:39:24.069 --> 01:39:26.859 is that on a large scale, only areas and large 1362 01:39:27.359 --> 01:39:31.279 ones are formed. There is also an interesting thing here. 1363 01:39:31.859 --> 01:39:35.060 This universe of the future will not be completely dark. 1364 01:39:35.859 --> 01:39:39.699 Many galaxies will be present for billions of years. Stars 1365 01:39:39.739 --> 01:39:43.350 will keep forming. However, with time, the speed of star 1366 01:39:43.369 --> 01:39:46.729 formation will decrease. Because the gas present in the galaxies 1367 01:39:48.430 --> 01:39:52.210 Dheere dheere samaapt hoti jaayegi. Nai peedi ke stars banne 1368 01:39:52.229 --> 01:39:56.229 ke liye kaccha padarth kam padhne lagayega. Aur tab, brahmand 1369 01:39:56.250 --> 01:40:00.590 me purane stars ki sankhya adhik hogi. Dheere dheere chamak 1370 01:40:00.630 --> 01:40:04.800 kam honay lagayegi. Ek samay aisa aayega jab adhikansh chamkile 1371 01:40:04.840 --> 01:40:09.340 neele stars samaapt hot chuke honge. Unki jagah lambay samay 1372 01:40:09.380 --> 01:40:13.239 tak jivit rehne wale chote aur thande stars bache honge. 1373 01:40:14.439 --> 01:40:19.569 Brahmand ki kul roshni kam hoti jaayegi. But voids will 1374 01:40:20.210 --> 01:40:23.529 keep on increasing. The fewer structures there will be, the 1375 01:40:23.630 --> 01:40:26.869 more emptiness will be seen. And perhaps this will be 1376 01:40:26.890 --> 01:40:30.600 the biggest change in the future. Today we recognize the 1377 01:40:30.659 --> 01:40:36.720 universe through structures. Galaxies, nebulae, star clusters and superclusters. But 1378 01:40:36.739 --> 01:40:39.500 in the very distant future, the universe will probably be 1379 01:40:39.520 --> 01:40:42.399 recognized by its empty areas. What was once present in 1380 01:40:43.199 --> 01:40:47.670 the middle of structures, will become the most prominent thing. 1381 01:40:48.619 --> 01:40:52.470 This thought takes us to another possibility called heat death. 1382 01:40:53.270 --> 01:40:56.229 Heat death does not mean any explosion or destruction. It 1383 01:40:56.329 --> 01:41:00.109 is a very slow process. So slow that in comparison 1384 01:41:00.130 --> 01:41:02.689 to it, human history seems like a moment. In this state, 1385 01:41:02.710 --> 01:41:07.359 the use of cosmic energy loses its difference. The temperature 1386 01:41:07.399 --> 01:41:13.840 becomes almost the same. The creation of new structures stops. 1387 01:41:13.899 --> 01:41:21.279 Is it? Stars end. Galaxies calm down. And the universe 1388 01:41:21.939 --> 01:41:24.539 slowly moves towards a stable state. If such a future 1389 01:41:24.560 --> 01:41:28.060 really comes, then voids will have changed into huge structures 1390 01:41:28.439 --> 01:41:32.289 by that time. They will not just remain empty. They 1391 01:41:32.369 --> 01:41:35.710 will become the main reflection of the universe. But there 1392 01:41:35.729 --> 01:41:39.229 is also a calm beauty hidden in this whole thought. 1393 01:41:46.890 --> 01:41:51.229 We often consider

emptiness to be an absence. We feel 1394 01:41:51.250 --> 01:41:54.369 that where there is nothing, there is no importance. But 1395 01:41:54.409 --> 01:41:57.569 voids teach us something different. They tell us that sometimes 1396 01:41:57.590 --> 01:42:01.060 the biggest structure is the one which is not visible. 1397 01:42:01.069 --> 01:42:03.659 Sometimes the biggest effect is of the same thing which 1398 01:42:03.680 --> 01:42:07.579 seems almost absent. And maybe that's why scientists study voids 1399 01:42:08.060 --> 01:42:18.689 with so much interest. Because they don't just show the future. 1400 01:42:18.710 --> 01:42:22.270 They show the direction of the universe. They tell us 1401 01:42:22.289 --> 01:42:28.670 how the seven elements of time are arranged. How gravity 1402 01:42:28.750 --> 01:42:31.789 and expansion make a balance with each other. How empty 1403 01:42:31.869 --> 01:42:38.149 areas slowly grow. And how in billions of years the 1404 01:42:38.270 --> 01:42:43.720 entire cosmic landscape changes. If we look at the present 1405 01:42:43.760 --> 01:42:48.909 from that far-off future, then today's universe will seem to 1406 01:42:48.930 --> 01:42:55.260 be living in an extraordinary way. Today, countless galaxies are present. Today, 1407 01:42:55.659 --> 01:43:00.899 stars are being born. Today, the cosmic web is clearly visible. Today, 1408 01:43:00.920 --> 01:43:06.970 there are voids, but they do not dominate the entire universe. 1409 01:43:06.979 --> 01:43:09.350 We are living in an era where structure and emptiness 1410 01:43:09.789 --> 01:43:14.449 are both present together, in a balance. But with time, 1411 01:43:14.470 --> 01:43:19.810 this balance will change. And finally, emptiness will become more prominent. Here, 1412 01:43:19.899 --> 01:43:23.460 the story of voids is not just the story of astronomy. 1413 01:43:23.560 --> 01:43:26.899 It becomes the story of time. It becomes the story 1414 01:43:26.920 --> 01:43:29.680 of change. And it takes us to a thought that 1415 01:43:29.699 --> 01:43:34.189 goes a little further than science. When we look at 1416 01:43:34.199 --> 01:43:43.430 the largest empty areas of the universe, then we are 1417 01:43:43.890 --> 01:43:47.750 not only looking at the universe. We are also looking 1418 01:43:47.789 --> 01:43:49.989 at the question that has always been with man. What 1419 01:43:50.029 --> 01:43:53.050 is the actual meaning of emptiness? Is emptiness just the 1420 01:43:54.090 --> 01:43:57.670 absence of something? Or is there some deep peace hidden 1421 01:43:57.689 --> 01:44:01.220 within it? This question takes us beyond the physical structure 1422 01:44:01.300 --> 01:44:04.100 of the universe and leads us to a more peaceful 1423 01:44:04.119 --> 01:44:14.090 and spiritual journey. where the void is not just a 1424 01:44:14.130 --> 01:44:20.310 space of space, but becomes a thought. A thought that 1425 01:44:20.380 --> 01:44:23.779 has attracted the human mind for thousands of years, where 1426 01:44:24.300 --> 01:44:28.140 the void is not just a space of space, but 1427 01:44:28.579 --> 01:44:32.619 becomes a thought. A thought that has attracted the human 1428 01:44:32.680 --> 01:44:37.770 mind for thousands of years. When we think about the 1429 01:44:37.810 --> 01:44:41.949 largest voids of the universe, in the beginning they are 1430 01:44:41.989 --> 01:44:45.890 only astronomy ka vishay lagte hain. Vih galaxies ke beech 1431 01:44:45.930 --> 01:44:51.000 phailay huay, khali kshetra hain. Aise sthan, jahan bahut kam 1432 01:44:51.039 --> 01:44:55.279 taare hain, bahut kam prakash hain, aur bahut kam padarth hain. 1433 01:44:56.180 --> 01:44:58.819 Lekin jaise jaise hum is vichar ke saath thoda samay 1434 01:44:58.859 --> 01:45:02.750 batate hain, ek alag ahsas paida honi lagta hain. Hum 1435 01:45:02.770 --> 01:45:06.229 mehsoos karte hain ki khalipan keval antariksh mein hi nahi hain. 1436 01:45:06.989 --> 01:45:10.250 Khalipan ek anubhav bhi hain, ek vichar bhi hain, aur 1437 01:45:10.350 --> 01:45:14.760 shayad ek shikshak bhi hain. In human history, almost every 1438 01:45:14.779 --> 01:45:18.479 civilization has tried to understand the meaning of emptiness in 1439 01:45:18.649 --> 01:45:24.229 some form or another. Some people saw it as fear, 1440 01:45:24.250 --> 01:45:29.649 some considered it a mystery, and some found peace in it. 1441 01:45:29.689 --> 01:45:32.670 Seeing the vast voids of the universe, this becomes even 1442 01:45:32.689 --> 01:45:38.079 more interesting. Because there, to some extent, the same situation 1443 01:45:38.140 --> 01:45:42.399 is seen, about which the philosophical and spiritual traditions have 1444 01:45:42.439 --> 01:45:47.479 been talking for thousands of years. When we look at 1445 01:45:47.930 --> 01:45:51.529 a huge galaxy cluster, then there is movement, there is movement, 1446 01:45:51.550 --> 01:45:56.989 there are clashes, there are both creation and destruction. But 1447 01:45:57.010 --> 01:46:00.949 there is silence in the voids. And sometimes, silence also 1448 01:46:00.970 --> 01:46:05.890 gives a kind of information. In Buddhist darshan, there is 1449 01:46:05.909 --> 01:46:10.039 a thought, which is called zero. This does not mean 1450 01:46:10.060 --> 01:46:13.229 that nothing is present. This does not mean that the 1451 01:46:13.289 --> 01:46:18.109 world is meaningless. Rather, this means that things are not stationary. 1452 01:46:18.130 --> 01:46:22.050 They keep changing. They are connected to each other. And 1453 01:46:22.069 --> 01:46:27.569 their existence depends on many reasons and situations. If we 1454 01:46:27.590 --> 01:46:31.260 look at the universe, then something looks the same. Galaxies 1455 01:46:31.270 --> 01:46:41.220 are not stationary. Stars are not stable. Planets are not stable. 1456 01:46:41.239 --> 01:46:43.560 Even the biggest cosmic structures are not stable. Everything keeps 1457 01:46:44.220 --> 01:46:46.840 changing

in millions of years. What is present today will 1458 01:46:47.579 --> 01:46:52.529 change one day. What is shining today will become calm 1459 01:46:52.550 --> 01:46:56.390 one day. And what is created today can become part 1460 01:46:56.409 --> 01:47:00.029 of another creation in the future. Voids remind us of 1461 01:47:00.069 --> 01:47:08.409 this change. They show us that Brahmand keval padarth se 1462 01:47:08.430 --> 01:47:12.609 nahi bana. Vah khali sthan se bhi bana hai. Aur kabhi-kabhi, 1463 01:47:13.069 --> 01:47:17.390 vahhi khali sthan sabse adhik mahatva poon hota hai. Stoic 1464 01:47:17.430 --> 01:47:21.829 darshan me bhi ek rochak vichar milta hai. Prachin Stoic 1465 01:47:21.869 --> 01:47:25.350 vicharko ka maanna tha ki, manushri ko un cheezo ko 1466 01:47:25.409 --> 01:47:29.600 swikar karna seekhna chahiye, jo uske niyantran se bahar hai. 1467 01:47:30.300 --> 01:47:34.140 Brahmand ka akar hamare niyantran me nahi hai. Samay ka 1468 01:47:34.159 --> 01:47:38.090 pravah hamare niyantran me nahi hai. The birth and death 1469 01:47:38.470 --> 01:47:40.170 of galaxies is not in our control. But we can 1470 01:47:40.189 --> 01:47:42.310 try to understand them. We can see them. We can 1471 01:47:42.390 --> 01:47:45.470 feel surprised about them. And maybe this is enough. When 1472 01:47:45.510 --> 01:47:49.289 we think about a huge void, which has been spreading 1473 01:47:50.369 --> 01:47:53.369 for hundreds of millions of light years, then we also 1474 01:47:53.390 --> 01:47:55.430 remember the dimension of our life. Our life is of 1475 01:47:55.449 --> 01:48:08.210 a few decades. A civilization can last for a few 1476 01:48:08.229 --> 01:48:12.489 thousand years. But voids tell the story of billions of years. 1477 01:48:12.520 --> 01:48:16.039 They are present at times when it is difficult to understand. Still, 1478 01:48:16.500 --> 01:48:22.859 there is a strange thing. such a vast difference, we 1479 01:48:22.899 --> 01:48:27.979 can feel their connection. Because man has always been looking 1480 01:48:28.000 --> 01:48:31.199 towards the sky. Thousands of years ago, people used to 1481 01:48:31.699 --> 01:48:34.960 look at the stars at night. They still do today. 1482 01:48:35.000 --> 01:48:39.899 And perhaps, even after thousands of years, Koi na koi 1483 01:48:40.260 --> 01:48:45.609 unhe dekh raha hoga. Aakash badalta hai, lekin jiggyasa bani 1484 01:48:45.630 --> 01:48:50.149 rehti hai. Shayad, yahi waha cheez hai jo hume brahmand 1485 01:48:50.189 --> 01:48:55.010 se jodti hai. Voids ki kahaani bhi antata jiggyasa ki 1486 01:48:55.029 --> 01:49:00.159 kahaani hai. Jab vaigyanikon ne pehli baar Botes Void khoja tha, 1487 01:49:00.680 --> 01:49:03.840 toh ne vishwas nahi hua tha ki itna bada khali 1488 01:49:03.859 --> 01:49:07.859 kshetra vastav me maujood ho sakta hai. Phir aur avlokan hua. 1489 01:49:08.630 --> 01:49:12.390 aur adhik voids mile. Phir unse jode naye prashna saamne aaye. 1490 01:49:13.069 --> 01:49:19.960

Dark matter, dark energy, cosmic expansion, Hubble tension, observable universe. 1491 01:49:21.020 --> 01:49:24.260 Har uttar ne ek naya prashna paida kiya. Aur yahi 1492 01:49:24.279 --> 01:49:29.109 vigyan ka swabhav hai. Vigyan keval uttaron ka sangreh nahi hai. 1493 01:49:29.710 --> 01:49:34.210 Vah prashna, poochne ki kala bhi hai. Voids hume yeh 1494 01:49:34.229 --> 01:49:37.869 baat bahut sundar tarike se sikhate hain. Because they are 1495 01:49:37.890 --> 01:49:41.170 like questions themselves. When we look at a galaxy, we 1496 01:49:41.189 --> 01:49:43.300 see something. But when we look at a void, we 1497 01:49:43.380 --> 01:49:48.699 think about something that is not visible. And sometimes, absence 1498 01:49:48.720 --> 01:49:52.779 is as important as presence. If there are only sounds 1499 01:49:52.819 --> 01:49:55.220 in a music, and there is no rest between them, 1500 01:49:55.239 --> 01:50:06.840 then it will not seem like music. If there is 1501 01:50:06.939 --> 01:50:12.020 only colour in a picture and there is no empty space, 1502 01:50:12.039 --> 01:50:15.819 then it will be difficult to understand it. Similarly, voids 1503 01:50:15.899 --> 01:50:18.390 are also necessary in the universe. They are not just 1504 01:50:18.430 --> 01:50:21.050 empty areas. They are part of the entire cosmic structure. 1505 01:50:21.090 --> 01:50:24.930 They give meaning to galaxies. They give shape to filaments. 1506 01:50:24.970 --> 01:50:27.630 They help us understand where the matter is and where 1507 01:50:27.689 --> 01:50:31.350 it is not. And perhaps for this reason, emptiness is 1508 01:50:32.170 --> 01:50:39.380 only kami ke roop mein nahin dekhna chahiye. Kabhi-kabhi khalipan 1509 01:50:39.420 --> 01:50:43.680 sambhavana bhi hota hai, kabhi-kabhi khalipan santulan bhi hota hai, 1510 01:50:44.260 --> 01:50:48.199 aur kabhi-kabhi khalipan shanti bhi hota hai. Yadhi hum kalpna 1511 01:50:48.239 --> 01:50:50.600 karen ki hum kisi vishal void ke beech mein tair 1512 01:50:50.619 --> 01:50:54.289 rahe hain, to shayad shurwaat mein hume akela pan mehsoos ho. 1513 01:50:54.890 --> 01:50:59.689 Charon aur andhkar, door-door tak koi galaxy nahi, koi chamak nahi, 1514 01:51:00.069 --> 01:51:03.649 koi parichit sanrachna nahi. But if we look at that 1515 01:51:03.670 --> 01:51:08.510 scene a little longer, then maybe another feeling will be born. 1516 01:51:09.029 --> 01:51:11.989 A deep stability. A peace that cannot be found in 1517 01:51:12.010 --> 01:51:15.770 any city. A silence in which only the existence of 1518 01:51:16.050 --> 01:51:18.939 the universe is left. And maybe this is the reason 1519 01:51:19.199 --> 01:51:21.699 why the story of Voids is not only scientific. It 1520 01:51:21.720 --> 01:51:25.100 also has an emotional side. It reminds us of our limits. 1521 01:51:25.119 --> 01:51:33.020 It makes us humble. It shows us how small we are. 1522 01:51:33.090 --> 01:51:38.189 But at the same time, it also shows us how 1523 01:51:38.270 --> 01:51:42.930 big our curiosity is. We are a species living on 1524 01:51:42.949 --> 01:51:46.989 a small planet. Still, we can study billions of light-years 1525 01:51:47.050 --> 01:51:51.449 distant civilizations. We can think about those areas where perhaps 1526 01:51:51.510 --> 01:51:53.510 no human being will ever reach. We can imagine the 1527 01:51:53.529 --> 01:52:02.090 largest empty areas of the universe. And this is a 1528 01:52:02.109 --> 01:52:06.649 wonderful thing in itself. Perhaps this is the greatest lesson 1529 01:52:06.729 --> 01:52:11.109 of words. Emptiness is not always absent. Sometimes it begins 1530 01:52:11.130 --> 01:52:14.729 to understand. Sometimes it tells us to slow down. Sometimes 1531 01:52:14.770 --> 01:52:18.529 it teaches us to listen. And sometimes it makes us 1532 01:52:18.550 --> 01:52:22.329 feel that our place in the vast universe is so 1533 01:52:22.369 --> 01:52:34.029 small but so unique. The more we understand the universe, 1534 01:52:34.689 --> 01:52:38.659 the more we feel that we are not different from it. 1535 01:52:38.689 --> 01:52:43.680 We are also a part of the same universe, made 1536 01:52:44.359 --> 01:52:47.600 of the same material, a part of the same history, 1537 01:52:47.680 --> 01:52:50.899 and a small part of the same peaceful universe story, 1538 01:52:50.920 --> 01:52:54.810 which began billions of years ago and continues today. Now, 1539 01:52:54.859 --> 01:52:57.939 at the end of this long journey, when we have 1540 01:52:57.960 --> 01:53:02.399 reached the end of the universe sabse bade voids tak 1541 01:53:02.420 --> 01:53:07.760 ki kahaani dekh li hai. Jab humne dark matter, dark energy, samay, 1542 01:53:08.100 --> 01:53:11.800 bhavishya aur khalipan ke arth par vichar kar liya hai. 1543 01:53:12.260 --> 01:53:15.779 Tab dheere dheere humare drishti phir se untaaro ki aur 1544 01:53:15.840 --> 01:53:19.279 lautti hai, jin se yeh poori kahaani shuru hoi thi. 1545 01:53:20.199 --> 01:53:24.210 Untaaro ki aur, jin ke bina na galaxies hoti, na grah, 1546 01:53:24.689 --> 01:53:27.970 aur na hi hum. Untaaro ki aur, jin ke bina 1547 01:53:28.010 --> 01:53:32.699 na galaxies hoti, na grah, and neither did we. When 1548 01:53:32.720 --> 01:53:36.479 we were at the beginning of this journey, we had 1549 01:53:36.579 --> 01:53:40.680 imagined the largest empty areas in the universe. We thought 1550 01:53:40.699 --> 01:53:44.010 that voids are only places where there is almost nothing. 1551 01:53:44.029 --> 01:53:46.829 But during this long journey, it became clear that voids 1552 01:53:46.869 --> 01:53:49.250 are not just empty places. They are an essential part 1553 01:53:49.289 --> 01:53:52.329 of the story of the universe. Galaxies tell us that 1554 01:53:59.300 --> 01:54:03.020 Where is matter present? But voids tell us that matter 1555 01:54:03.140 --> 01:54:06.699 is not present. It is. And by looking at these 1556 01:54:06.720 --> 01:54:10.239 two together, we

can understand the real picture of the universe. 1557 01:54:10.300 --> 01:54:14.380 We saw the cosmic web. We saw those huge filaments 1558 01:54:14.479 --> 01:54:16.640 which have been spread for billions of light years. We 1559 01:54:16.659 --> 01:54:21.979 traveled through the Boter's Void. We imagined those areas where 1560 01:54:22.010 --> 01:54:26.109 the number of galaxies is surprisingly low. We also saw 1561 01:54:29.289 --> 01:54:33.630 that how dark matter and dark energy are shaping the 1562 01:54:33.649 --> 01:54:39.550 structure of the entire universe. We also saw the future, 1563 01:54:39.569 --> 01:54:43.369 the time when galaxies will go far away, when voids 1564 01:54:43.390 --> 01:54:46.710 will grow bigger, when the universe will look much calmer 1565 01:54:46.930 --> 01:54:50.369 and more vibrant than before. But the most beautiful thing 1566 01:54:50.390 --> 01:54:55.060 in this whole story is that we ourselves are also 1567 01:54:55.100 --> 01:54:58.960 part of this universe. Many times when we think about 1568 01:54:59.000 --> 01:55:01.529 the huge size of the universe, we feel our existence 1569 01:55:01.590 --> 01:55:04.729 is very small. And this is true. A person lives 1570 01:55:05.390 --> 01:55:09.529 on a planet. That planet revolves around a star. That 1571 01:55:09.550 --> 01:55:12.609 star is a part of a galaxy. That galaxy is 1572 01:55:12.680 --> 01:55:15.359 a small part of the universe with billions of galaxies. 1573 01:55:15.380 --> 01:55:17.880 We are actually very small on this scale. But there 1574 01:55:18.640 --> 01:55:26.350 is a second side to the story. Hum chhote ho 1575 01:55:26.359 --> 01:55:30.949 sakte hain, lekin hum jagrook hain. Hum prashna pooch sakte hain. 1576 01:55:31.890 --> 01:55:36.630 Hum taaro ko dekh sakte hain. Hum brahmand ko samajhne 1577 01:55:36.649 --> 01:55:40.550 ki koshish kar sakte hain. Aur shayad, yahi baat hume 1578 01:55:40.609 --> 01:55:45.689 vishesh banati hain. Kyuki, jahan tak hume pata hai, iss 1579 01:55:45.770 --> 01:55:49.029 vishal brahmand mein hum hi aise prani hain, jo uske 1580 01:55:49.069 --> 01:55:53.569 baare mein soch sakte hain. Aap abhi, You can imagine 1581 01:55:53.609 --> 01:55:57.430 the largest voids of the universe on a small planet. 1582 01:55:57.449 --> 01:56:01.810 You can imagine the largest voids of the universe on 1583 01:56:01.829 --> 01:56:03.850 a small planet. You can imagine the largest voids of 1584 01:56:03.869 --> 01:56:09.279 the universe on a small planet. You can imagine the 1585 01:56:09.319 --> 01:56:12.659 largest voids of the universe on a small planet. You 1586 01:56:12.680 --> 01:56:17.100 can imagine the largest voids of the universe on a 1587 01:56:17.119 --> 01:56:28.989 small planet. is not a poetic statement. It is the truth. Carbon, oxygen, 1588 01:56:29.560 --> 01:56:34.439 calcium and other elements in our body were once formed 1589 01:56:34.479 --> 01:56:38.340 inside a star. A long time ago. That star fulfilled 1590 01:56:38.359 --> 01:56:41.000 its life. It spread matter in space. From that matter, 1591 01:56:41.439 --> 01:56:45.270 new stars were formed. New planets were formed. And finally, 1592 01:56:45.989 --> 01:56:47.970 we were formed. If we see it in one meaning, 1593 01:56:48.289 --> 01:56:51.189 then the universe is trying to understand itself. Because we 1594 01:56:51.770 --> 01:56:55.369 usi brahmand ka hissa hai. Jab hum aakash ki aur 1595 01:56:55.409 --> 01:56:59.069 dekhte hai, to dekhne wala bhi brahmand hai, aur jise 1596 01:56:59.130 --> 01:57:03.510 dekha ja raha hai, waha bhi brahmand hai. Shayad yahi 1597 01:57:03.550 --> 01:57:07.760 vichar is puri yatra ka sabse shant aur sundar nishkarsh hai. 1598 01:57:08.579 --> 01:57:12.560 Voids hume khalipan ke baare me sikhate hai. Galaxies hume 1599 01:57:12.840 --> 01:57:16.699 sanrachna ke baare me sikhate hai. Stars hume utpatti ke 1600 01:57:16.739 --> 01:57:20.850 baare me sikhate hai. Aur pura brahmand, He teaches us 1601 01:57:20.869 --> 01:57:23.829 about humility. The more we learn, the more we realize 1602 01:57:23.869 --> 01:57:26.340 that there is so much to know. Every search gives 1603 01:57:26.359 --> 01:57:28.979 birth to a new question. Behind every answer, a new 1604 01:57:29.000 --> 01:57:32.359 mystery is hidden. And perhaps this is the reason why 1605 01:57:32.380 --> 01:57:35.819 the universe never seems to rise. Its story does not end. 1606 01:57:35.920 --> 01:57:53.060 It continues to move forward. When you are listening to this, 1607 01:57:53.100 --> 01:57:57.630 new stars will be born somewhere far away. Galaxies will 1608 01:57:57.689 --> 01:58:01.069 be coming to each other somewhere. Black holes will be 1609 01:58:01.090 --> 01:58:04.489 melting the matter somewhere. And somewhere, huge voids will be 1610 01:58:04.489 --> 01:58:09.810 getting bigger and bigger. All this is happening without our knowledge. 1611 01:58:09.810 --> 01:58:12.869 The universe does not need our presence. Still, we are 1612 01:58:12.909 --> 01:58:15.720 fortunate that we can see it. We can understand it. 1613 01:58:15.770 --> 01:58:19.609 And we can feel surprised about it. Now, slowly, this 1614 01:58:19.649 --> 01:58:30.399 journey ends. Kalpana kijiye ki aap raat ke shant aakash 1615 01:58:30.420 --> 01:58:34.560 ke neeche khade hain. Upar asankhya taare hain. Un taaron 1616 01:58:34.579 --> 01:58:39.060 ke beech vishal doori hai. Un dooriyon ke beech galaxies hain. 1617 01:58:39.079 --> 01:58:42.840 Aur galaxies ke beech aise voids hain jo itne bade 1618 01:58:42.859 --> 01:58:46.479 hain ki maanav kalpana bhi unhe puri tarah nahi samajh sakti. 1619 01:58:47.159 --> 01:58:50.479 Phir bhi, yeh sab ek hi brahmand ka hissa hai. 1620 01:58:51.270 --> 01:58:55.409 Ek aisa brahmand jo arbon varshon se vikasit ho raha hai. 1621 01:58:56.069 --> 01:58:59.590 Ek aisa brahmand Jismein sanrachna bhi hai aur khalipan bhi. 1622 01:59:00.130 --> 01:59:03.510 Prakash bhi hai aur andhkar bhi. Prashna bhi hai aur 1623 01:59:03.569 --> 01:59:07.909 rahasya bhi. Aur shayad iss sari vishalta ke beech sabse 1624 01:59:07.949 --> 01:59:11.210 sundar baat yeh hai ki hum yahan hai. Hum isse 1625 01:59:11.229 --> 01:59:13.529 dekh rahe hain. Hum iske baare mein soch rahe hain. 1626 01:59:13.789 --> 01:59:16.989 Aur kuch kshano ke liye hum iss anant kahani ka 1627 01:59:17.029 --> 01:59:20.680 hissa ban rahe hain. Ab brahmand apni shant gati se 1628 01:59:20.699 --> 01:59:26.359 chalta rahega. Taare chamakte rahenge. Galaxies apni yatraayen jaari rakhenge. 1629 01:59:26.960 --> 01:59:31.380 Voids will spread slowly. And amidst this immense peace, the 1630 01:59:31.920 --> 01:59:36.720 night sky will always be spread over us. Peaceful, vast 1631 01:59:36.800 --> 01:59:41.100 and full of mysteries. If you liked this peaceful space 1632 01:59:41.119 --> 01:59:44.909 journey of Sleepy Space Science, then don't forget to like 1633 01:59:45.369 --> 01:59:49.449 the video. If you like to watch such long and 1634 01:59:49.890 --> 01:59:56.789 relaxing space documentaries, then subscribe to Sleepy Space Science so 1635 01:59:56.810 --> 01:59:58.600 that you can join us in our next space journey. 1636 01:59:58.649 --> 02:00:03.060 And before going to sleep, do let us know in 1637 02:00:03.100 --> 02:00:06.720 the comments, what should be the next documentary on. Do 1638 02:00:06.739 --> 02:00:09.960 you want to hear about the journey inside the black holes? 1639 02:00:10.000 --> 02:00:13.520 The whole secret of dark matter? The last future of 1640 02:00:13.649 --> 02:00:19.869 the universe? Or some other amazing cosmic mystery story? It 1641 02:00:20.949 --> 02:00:23.890 always feels good to read your suggestions. Now rest well. 1642 02:00:26.899 --> 02:00:30.970 aur brahmand ki iss shant yatra ko apne sapno me 1643 02:00:31.210 --> 02:00:33.960 aage badne dijiye. Shubh ratri.