1 00:00:01,000 --> 00:00:03,960 (MYSTERIOUS MUSIC) 2 00:00:12,400 --> 00:00:15,200 - [Narrator] Since the very beginning of time, 3 00:00:15,200 --> 00:00:21,710 man has looked to the night sky and asked the same questions, 4 00:00:22,720 --> 00:00:23,800 where are we? 5 00:00:23,800 --> 00:00:26,430 How far do the stars go? 6 00:00:26,430 --> 00:00:27,430 And are we alone? 7 00:00:30,040 --> 00:00:32,200 Today, these same questions linger 8 00:00:32,200 --> 00:00:35,770 in the minds of every human with an inquisitive nature. 9 00:00:38,440 --> 00:00:42,300 Is our world just a speck in an infinite universe, 10 00:00:42,300 --> 00:00:45,840 surrounded by many other worlds and species? 11 00:00:45,840 --> 00:00:49,400 Or is it possible that we are the only intelligent 12 00:00:49,400 --> 00:00:50,560 life in the universe? 13 00:00:53,800 --> 00:00:56,480 If our universe is truly infinite, 14 00:00:56,480 --> 00:00:59,160 then it is thought that anything that could happen 15 00:00:59,160 --> 00:01:03,670 has happened an infinite number of times. 16 00:01:03,670 --> 00:01:06,390 There will be infinite worlds and infinite 17 00:01:06,390 --> 00:01:08,050 intelligent life forms. 18 00:01:08,050 --> 00:01:10,560 Even infinite copies of ourselves. 19 00:01:13,070 --> 00:01:16,750 But we may also exist in an infinite universe, which 20 00:01:16,750 --> 00:01:20,990 is one of infinitely many universes, each existing in 21 00:01:20,990 --> 00:01:22,730 possibly infinite dimensions. 22 00:01:25,470 --> 00:01:28,910 This series explores the many theories and ideas 23 00:01:28,910 --> 00:01:31,950 as to where we all are in this immense system, which 24 00:01:31,950 --> 00:01:34,430 seem to come from nothing in the Big Bang 25 00:01:34,430 --> 00:01:39,190 13.8 billion years ago. 26 00:01:39,190 --> 00:01:44,350 New understanding says this may not be the full story. 27 00:01:44,350 --> 00:01:46,230 We look at the ideas and theories 28 00:01:46,230 --> 00:01:50,110 from a human perspective, and hear from our best scientific 29 00:01:50,110 --> 00:01:53,310 minds, who spend their lives trying to understand 30 00:01:53,310 --> 00:01:54,570 these monumental concepts. 31 00:01:54,570 --> 00:01:56,470 (EPIC MUSIC) 32 00:01:56,470 --> 00:01:59,950 How do we try and understand what may be simply 33 00:01:59,950 --> 00:02:02,130 beyond human comprehension? 34 00:02:45,600 --> 00:02:48,630 - [Narrator] If our universe is finite, 35 00:02:48,630 --> 00:02:50,110 then it would seem to indicate that 36 00:02:50,110 --> 00:02:52,110 there would be some kind of edge 37 00:02:52,110 --> 00:02:53,680 or boundary to the universe. 38 00:02:53,680 --> 00:02:55,910 (INTRIGUING MUSIC) 39 00:02:55,910 --> 00:02:59,660 If this is the case, what possible shape or reality 40 00:02:59,660 --> 00:03:02,740 would this take? 41 00:03:02,740 --> 00:03:08,940 Is it possible that space could just stop at a certain point? 42 00:03:08,940 --> 00:03:13,170 Is there anything beyond this possible boundary? 43 00:03:13,170 --> 00:03:15,680 - [Speaker 1] Well, we haven't found the edge of space, 44 00:03:15,680 --> 00:03:20,220 so maybe it does go for infinity and we haven't really 45 00:03:20,220 --> 00:03:22,060 found the beginning of space, so maybe 46 00:03:22,060 --> 00:03:23,680 it's been going for infinity. 47 00:03:27,150 --> 00:03:29,380 - [Speaker 2] The idea that the universe 48 00:03:29,380 --> 00:03:32,780 is finite is the biggest problem I 49 00:03:32,780 --> 00:03:33,970 have wrapping my head around. 50 00:03:36,530 --> 00:03:39,860 - [Speaker 3] People thought the universe was simply finite. 51 00:03:39,860 --> 00:03:41,380 You know, you went to the end. 52 00:03:41,380 --> 00:03:42,780 And there's a lot of puzzlement about that 53 00:03:42,780 --> 00:03:44,280 because you're always inclined to wonder, 54 00:03:44,280 --> 00:03:47,000 well, what's beyond the end, if it really is finite? 55 00:03:47,000 --> 00:03:49,100 So that-- that led to a lot of puzzlement, 56 00:03:49,100 --> 00:03:50,900 and that made people think, well, maybe the universe 57 00:03:50,900 --> 00:03:54,670 really is infinite. 58 00:03:54,670 --> 00:03:57,610 - [Speaker 1] If there is an edge to our universe 59 00:03:57,610 --> 00:04:01,770 or our multiverse, I think that means we're held 60 00:04:01,770 --> 00:04:04,390 together by some center. 61 00:04:04,390 --> 00:04:09,100 If there's an edge, to me, there would be a center. 62 00:04:09,100 --> 00:04:11,090 - [Speaker 4] The idea of a boundary is something 63 00:04:11,090 --> 00:04:13,310 that we are all used to. 64 00:04:13,310 --> 00:04:16,110 Everything that we think of your head, this room, 65 00:04:16,110 --> 00:04:19,760 that a car, it has a center and then it has an edge 66 00:04:19,760 --> 00:04:21,110 and everything is inside. 67 00:04:21,110 --> 00:04:22,830 Your brain has a center and an edge. 68 00:04:22,830 --> 00:04:24,850 And then when you say, if it's expanding, 69 00:04:24,850 --> 00:04:27,930 it expands into the surrounding space. 70 00:04:27,930 --> 00:04:30,730 That is the most common thought and the most common 71 00:04:30,730 --> 00:04:32,350 misconception about the universe, 72 00:04:32,350 --> 00:04:35,290 because the universe does not have a center, 73 00:04:35,290 --> 00:04:38,130 therefore it can expand without expanding 74 00:04:38,130 --> 00:04:40,330 into anything around it. 75 00:04:40,330 --> 00:04:41,910 There is no around it. 76 00:04:41,910 --> 00:04:44,930 There is no outside it to expand into. 77 00:04:44,930 --> 00:04:46,630 But you say, it has to have that. 78 00:04:46,630 --> 00:04:49,230 It has to have that because everything I know is like that. 79 00:04:49,230 --> 00:04:53,100 Well, welcome to general relativity. 80 00:04:53,100 --> 00:04:56,440 (ENIGMATIC MUSIC) 81 00:04:56,440 --> 00:04:58,260 - [Narrator] Throughout history, 82 00:04:58,260 --> 00:05:02,040 man has had many ideas as to the extent of the universe, 83 00:05:02,040 --> 00:05:05,320 with an Italian Giordano Bruno being one of the first 84 00:05:05,320 --> 00:05:07,400 to declare that the universe is truly 85 00:05:07,400 --> 00:05:11,720 infinite and that the stars were in fact, 86 00:05:11,720 --> 00:05:12,720 just distant suns. 87 00:05:15,240 --> 00:05:18,310 But what are the alternatives if the universe is bounded? 88 00:05:20,880 --> 00:05:24,080 The most popular theory is that the universe is bounded 89 00:05:24,080 --> 00:05:27,310 by some sort of a sphere. 90 00:05:27,310 --> 00:05:30,660 - [Speaker 3] In the 20th century, with modern cosmology, 91 00:05:30,660 --> 00:05:33,360 people began to pedal back from the idea that the universe was 92 00:05:33,360 --> 00:05:36,800 infinite and think that it was finite, 93 00:05:36,800 --> 00:05:38,260 but nonetheless unbounded. 94 00:05:38,260 --> 00:05:40,340 So just like on the surface of a sphere, 95 00:05:40,340 --> 00:05:42,640 if you kind of walk around on the surface of a sphere 96 00:05:42,640 --> 00:05:45,220 and you stay on the surface, you'll never come to an edge. 97 00:05:45,220 --> 00:05:46,760 You'll never come to a boundary. 98 00:05:46,760 --> 00:05:48,640 But nonetheless, there's a fixed amount of space 99 00:05:48,640 --> 00:05:50,240 on that surface it's finite. 100 00:05:50,240 --> 00:05:51,740 So people thought the universe was like that. 101 00:05:51,740 --> 00:05:53,920 There was a fixed amount of space in it, 102 00:05:53,920 --> 00:05:56,280 a fixed amount of volume in it, but that no matter 103 00:05:56,280 --> 00:05:58,740 how far you traveled, you'd never come to a boundary. 104 00:05:58,740 --> 00:06:00,840 You'd, you know-- you'd just end up in other parts 105 00:06:00,840 --> 00:06:01,910 of this finite space. 106 00:06:04,800 --> 00:06:07,340 - [Speaker 5] The one thing as a physicist, 107 00:06:07,340 --> 00:06:10,380 I can tell you is that the universe, 108 00:06:10,380 --> 00:06:14,640 if it's flat in terms of space time, will go on for infinity. 109 00:06:14,640 --> 00:06:18,920 But what we've measured is that it's pretty flat. 110 00:06:18,920 --> 00:06:21,960 It might have a slight curve, we can't tell. 111 00:06:21,960 --> 00:06:23,560 That means, in just the same way 112 00:06:23,560 --> 00:06:28,400 that the Earth looks pretty flat as I look out around me. 113 00:06:28,400 --> 00:06:31,480 That's because the curvature is enormous 114 00:06:31,480 --> 00:06:32,920 in the sense of the radius of the Earth 115 00:06:32,920 --> 00:06:34,520 is vast on our scales. 116 00:06:34,520 --> 00:06:37,240 And if I can see a slight curve to that, say, a ship going 117 00:06:37,240 --> 00:06:38,800 over the horizon, the base of that ship 118 00:06:38,800 --> 00:06:40,960 disappears from view first, well, I 119 00:06:40,960 --> 00:06:46,040 can see an implication of the curvature of that Earth. 120 00:06:46,040 --> 00:06:51,470 I can't tell the difference between a universe that 121 00:06:51,470 --> 00:06:54,710 goes on forever and one that will 122 00:06:54,710 --> 00:06:59,350 wrap back on itself after some impossibly large 123 00:06:59,350 --> 00:07:01,150 distance traveled. 124 00:07:01,150 --> 00:07:04,590 In the same way that you can walk around the Earth 125 00:07:04,590 --> 00:07:06,470 and you will come back to where you started. 126 00:07:06,470 --> 00:07:10,090 But if I made the Earth a trillion kilometers, 127 00:07:10,090 --> 00:07:13,470 it would really appear to you as if it were infinite. 128 00:07:13,470 --> 00:07:14,950 That curvature of the ground would 129 00:07:14,950 --> 00:07:17,230 be so slight it would take so long 130 00:07:17,230 --> 00:07:19,990 to even notice it was beginning to come back on itself. 131 00:07:19,990 --> 00:07:23,990 To the ability to measure, it would appear the same 132 00:07:23,990 --> 00:07:25,250 as if it were infinite. 133 00:07:28,210 --> 00:07:30,550 - [Narrator] Again, we are up against the limits 134 00:07:30,550 --> 00:07:33,510 of our technology, which leaves an open 135 00:07:33,510 --> 00:07:38,330 question as to the extent of our universe. 136 00:07:38,330 --> 00:07:41,550 - [Speaker 6] We look out as far as we can, 137 00:07:41,550 --> 00:07:46,090 and the universe just stays pretty much the same all over. 138 00:07:46,090 --> 00:07:50,920 We see no sign of an edge or a tailing off. 139 00:07:50,920 --> 00:07:53,220 - [Narrator] Although we cannot be certain, 140 00:07:53,220 --> 00:07:56,220 as we look further into space, it appears 141 00:07:56,220 --> 00:07:58,700 as if the universe is continuing to expand 142 00:07:58,700 --> 00:08:01,780 at an ever-increasing rate. 143 00:08:01,780 --> 00:08:04,420 As it looks to us now, it does seem 144 00:08:04,420 --> 00:08:07,020 to indicate an infinite universe 145 00:08:07,020 --> 00:08:10,250 without an edge or boundary. 146 00:08:10,250 --> 00:08:11,900 - [Speaker 6] You somehow got to contrive 147 00:08:11,900 --> 00:08:17,260 some complicated explanation to make an edge of the universe. 148 00:08:17,260 --> 00:08:20,180 And we have this principle in science, Occam's razor, which 149 00:08:20,180 --> 00:08:23,420 says, on the whole, the simplest explanations 150 00:08:23,420 --> 00:08:25,300 tend to be the right ones. 151 00:08:25,300 --> 00:08:27,600 And the simplest explanation is, 152 00:08:27,600 --> 00:08:29,400 well, when we look at the universe, 153 00:08:29,400 --> 00:08:31,140 it looks the same everywhere. 154 00:08:31,140 --> 00:08:33,860 We don't see any evidence of an edge 155 00:08:33,860 --> 00:08:36,790 or anything slowing down or reducing or anything like that. 156 00:08:36,790 --> 00:08:39,460 So Occam's razor says, well, the simplest explanation is it 157 00:08:39,460 --> 00:08:43,370 just keeps on going as it is. 158 00:08:43,370 --> 00:08:45,380 - [Narrator] This expansion of the universe 159 00:08:45,380 --> 00:08:50,220 is evidence that the universe is getting larger and larger. 160 00:08:50,220 --> 00:08:53,780 But can we rule out some kind of edge or boundary, 161 00:08:53,780 --> 00:08:57,500 as we can only see so far into the universe in what is called 162 00:08:57,500 --> 00:09:00,820 the observable universe? 163 00:09:00,820 --> 00:09:02,700 - [Speaker 7] If we keep on extrapolating what 164 00:09:02,700 --> 00:09:05,620 we've already seen, then the universe gets 165 00:09:05,620 --> 00:09:07,420 bigger and bigger and bigger, and we 166 00:09:07,420 --> 00:09:09,200 keep on multiplying things. 167 00:09:09,200 --> 00:09:10,540 And the older the universe, the bigger 168 00:09:10,540 --> 00:09:12,240 the multiplication factor. 169 00:09:12,240 --> 00:09:16,940 We have already strong evidence of things expanding by at least 170 00:09:16,940 --> 00:09:18,900 30 orders of magnitude. 171 00:09:18,900 --> 00:09:21,740 That's taking something the size of a golf ball 172 00:09:21,740 --> 00:09:23,810 to the size of the current universe. 173 00:09:23,810 --> 00:09:24,980 And we have many reasons to believe 174 00:09:24,980 --> 00:09:26,700 it's even more than that. 175 00:09:26,700 --> 00:09:29,100 Just because we think the universe goes beyond the part 176 00:09:29,100 --> 00:09:30,940 that we can just see, it doesn't suddenly 177 00:09:30,940 --> 00:09:35,860 end just conveniently beyond the 13.8 billion years of it 178 00:09:35,860 --> 00:09:36,880 that we can see. 179 00:09:39,740 --> 00:09:41,700 - [Narrator] Infinity is the concept 180 00:09:41,700 --> 00:09:45,380 of a universe that never ends. 181 00:09:45,380 --> 00:09:48,650 However, what if our universe is in an endless rebirthing 182 00:09:48,650 --> 00:09:53,210 process where one universe dies and another is born 183 00:09:53,210 --> 00:09:55,120 in an infinite cyclic process? 184 00:09:57,770 --> 00:10:01,930 - [Speaker 8] I can imagine the universe as it is now expanding 185 00:10:01,930 --> 00:10:04,050 and expanding and expanding until it gets to the point that 186 00:10:04,050 --> 00:10:06,930 it starts to contract and get smaller again, 187 00:10:06,930 --> 00:10:10,490 and can come down to this infinitesimally small point 188 00:10:10,490 --> 00:10:13,170 and then (IMITATES EPLOSION) explode out again 189 00:10:13,170 --> 00:10:14,260 to create another universe-- 190 00:10:14,260 --> 00:10:15,930 (EXPLOSION) 191 00:10:15,930 --> 00:10:18,190 --that may be entirely different to the-- to the one 192 00:10:18,190 --> 00:10:19,190 that we have now. 193 00:10:22,190 --> 00:10:24,190 - [Speaker 7] I think most people, 194 00:10:24,190 --> 00:10:27,250 including myself, find it very easy of understanding 195 00:10:27,250 --> 00:10:28,470 a cyclic universe. 196 00:10:28,470 --> 00:10:31,330 So it turns out through the equations of general relativity 197 00:10:31,330 --> 00:10:33,690 and the simplest form, you could have 198 00:10:33,690 --> 00:10:35,810 a universe that is finite. 199 00:10:35,810 --> 00:10:39,370 This is a universe that was born in a Big Bang, 200 00:10:39,370 --> 00:10:44,210 it rises and slows down, reaches a maximum size, 201 00:10:44,210 --> 00:10:47,080 starts to collapse and then ends. 202 00:10:47,080 --> 00:10:50,600 And so what happens before the Big Bang 203 00:10:50,600 --> 00:10:54,760 and what happens after the Gnab Gib, the Big Bang in reverse, 204 00:10:54,760 --> 00:10:57,240 well, that's someone's imagination. 205 00:10:57,240 --> 00:11:00,080 And you could imagine that maybe it just keeps on going on 206 00:11:00,080 --> 00:11:01,940 and on and on and on and on. 207 00:11:01,940 --> 00:11:05,380 (DRAMATIC MUSIC) 208 00:11:08,330 --> 00:11:10,760 - [Speaker 9] A long time ago, people thought 209 00:11:10,760 --> 00:11:12,440 that the universe was actually something 210 00:11:12,440 --> 00:11:14,200 called a cyclic universe. 211 00:11:14,200 --> 00:11:16,560 So the Big Bang happened, the big-- the universe 212 00:11:16,560 --> 00:11:20,140 would stop growing, gravity would collapse back on itself, 213 00:11:20,140 --> 00:11:22,100 and then the Big Bang would kind of reunite. 214 00:11:22,100 --> 00:11:25,100 So you get this, you know, boom, boom. 215 00:11:25,100 --> 00:11:28,420 So you just get this kind of oscillating almost universe. 216 00:11:28,420 --> 00:11:31,300 Now, we know that's not true right now, that our universe 217 00:11:31,300 --> 00:11:32,300 isn't doing it. 218 00:11:32,300 --> 00:11:33,460 It's actually speeding up. 219 00:11:33,460 --> 00:11:36,240 So it's growing faster and faster and faster. 220 00:11:36,240 --> 00:11:38,200 But some people have hypothesized that the universe 221 00:11:38,200 --> 00:11:40,870 will grow so much it'll rip itself apart in something 222 00:11:40,870 --> 00:11:41,870 called the Big Rip. 223 00:11:41,870 --> 00:11:42,920 (MYSTERIOUS MUSIC) 224 00:11:42,920 --> 00:11:45,840 Now, if you're ripping the entire amount of the universe, 225 00:11:45,840 --> 00:11:47,320 you're ripping all of the energy 226 00:11:47,320 --> 00:11:49,680 and all of the matter of that universe. 227 00:11:49,680 --> 00:11:52,720 And when that happens, you're actually 228 00:11:52,720 --> 00:11:55,440 creating the conditions of a new Big Bang. 229 00:11:55,440 --> 00:11:59,880 So if our universe rips itself apart, you could in some ways 230 00:11:59,880 --> 00:12:03,240 create a new universe through a new Big Bang. 231 00:12:03,240 --> 00:12:05,430 So you could get this replicating system. 232 00:12:12,110 --> 00:12:15,160 - [Speaker 7] It could well be that the Big Bang was just 233 00:12:15,160 --> 00:12:17,400 one of an infinite number of events 234 00:12:17,400 --> 00:12:18,900 in a much larger universe. 235 00:12:18,900 --> 00:12:22,000 So there are many ways that the universe could have always 236 00:12:22,000 --> 00:12:24,560 existed, or essentially has a time 237 00:12:24,560 --> 00:12:28,550 arrow that goes back to an infinite length into the past. 238 00:12:32,130 --> 00:12:34,600 - [Speaker 10] Once you think that you have 239 00:12:34,600 --> 00:12:37,440 universes giving rise to-- 240 00:12:37,440 --> 00:12:40,600 to new universes in a sort of like a birth like process, 241 00:12:40,600 --> 00:12:43,270 I don't think there's any reason to think, um-- 242 00:12:43,270 --> 00:12:46,790 that-- that process goes back finitely 243 00:12:46,790 --> 00:12:48,170 as opposed to infinitely. 244 00:12:51,550 --> 00:12:54,110 I think at this point, we have no experimental data 245 00:12:54,110 --> 00:12:55,470 because we're positing things that we 246 00:12:55,470 --> 00:12:57,970 no longer can have any kind of experimental access to. 247 00:12:57,970 --> 00:13:01,990 We can only really get to, um, see the stuff that's going 248 00:13:01,990 --> 00:13:03,130 on in our own universe. 249 00:13:03,130 --> 00:13:04,810 And even then, not all of that. 250 00:13:09,660 --> 00:13:11,510 - [Narrator] If an edge or boundary 251 00:13:11,510 --> 00:13:16,430 to the universe exists, then nothing has to exist. 252 00:13:16,430 --> 00:13:19,950 Although saying nothing exists suggests there is something 253 00:13:19,950 --> 00:13:22,750 there in the first place. 254 00:13:22,750 --> 00:13:25,910 Nothing is an equally hard concept for humans 255 00:13:25,910 --> 00:13:28,080 to understand, as is infinity. 256 00:13:28,080 --> 00:13:30,820 (OMINOUS MUSIC) 257 00:13:30,820 --> 00:13:33,210 - [Speaker 1] Beyond the edge of the universe, 258 00:13:33,210 --> 00:13:39,750 if the universe had an edge and there being nothing, I guess 259 00:13:39,750 --> 00:13:42,650 why can't there be nothing? 260 00:13:42,650 --> 00:13:44,420 - [Speaker 2] The idea of nothing is-- 261 00:13:44,420 --> 00:13:50,550 is just as inconceivable and possibly unhelpful as infinity. 262 00:13:50,550 --> 00:13:52,180 - [Speaker 5] Nothing is as hard 263 00:13:52,180 --> 00:13:57,250 a concept to get our heads around as infinitely something. 264 00:13:57,250 --> 00:13:59,860 - [Speaker 7] I find nothingness more 265 00:13:59,860 --> 00:14:01,440 uncomfortable than infinity. 266 00:14:01,440 --> 00:14:03,220 Infinity makes sense to me. 267 00:14:03,220 --> 00:14:05,900 Nothingness having something truly 268 00:14:05,900 --> 00:14:10,460 born out of absolutely nothing, that logically seems-- 269 00:14:10,460 --> 00:14:12,740 does not make sense to me. 270 00:14:12,740 --> 00:14:15,980 - [Narrator] To try to answer the question of whether nothing 271 00:14:15,980 --> 00:14:19,980 exists, scientists conducted experiments where they created 272 00:14:19,980 --> 00:14:23,660 an absolute vacuum in space. 273 00:14:23,660 --> 00:14:27,210 What they discovered was completely unexpected. 274 00:14:27,210 --> 00:14:30,460 - [Speaker 5] We think if you take this pocket in front of me 275 00:14:30,460 --> 00:14:31,720 and you take all those atoms out, 276 00:14:31,720 --> 00:14:35,900 and you keep pumping them out and it looks empty in the most 277 00:14:35,900 --> 00:14:39,080 pure vacuum imaginable, far beyond anything, 278 00:14:39,080 --> 00:14:44,230 even in the depths of space, you take every single atom out, 279 00:14:44,230 --> 00:14:45,890 and then you look and you realize 280 00:14:45,890 --> 00:14:47,940 there's still something there. 281 00:14:50,710 --> 00:14:53,570 - [Speaker 4] There is a seething froth of virtual 282 00:14:53,570 --> 00:14:56,130 particles coming into and out of existence 283 00:14:56,130 --> 00:14:57,510 that's irreducible. 284 00:14:57,510 --> 00:14:58,610 You can't get rid of it. 285 00:14:58,610 --> 00:14:59,910 You know, I could get rid of the sound, 286 00:14:59,910 --> 00:15:01,010 I could get rid of the neutrinos, 287 00:15:01,010 --> 00:15:02,950 I could get rid of the-- the air, 288 00:15:02,950 --> 00:15:06,230 but I cannot get rid of the structure of the vacuum, 289 00:15:06,230 --> 00:15:08,050 which are these irreducible particles coming 290 00:15:08,050 --> 00:15:09,490 into and out of existence. 291 00:15:09,490 --> 00:15:11,290 So the idea of saying that there's nothing there 292 00:15:11,290 --> 00:15:13,310 is kind of a silly old-fashioned thing. 293 00:15:13,310 --> 00:15:14,610 Just throw it out. 294 00:15:14,610 --> 00:15:18,700 There is no such thing as nothing. 295 00:15:18,700 --> 00:15:22,050 - [Narrator] Perhaps this is true within our universe. 296 00:15:22,050 --> 00:15:24,690 But if there was an outside of the universe, 297 00:15:24,690 --> 00:15:28,430 could there be absolute nothingness? 298 00:15:28,430 --> 00:15:32,210 - [Speaker 7] You know, your choice is nothingness in its 299 00:15:32,210 --> 00:15:37,130 absolute form or infinity. 300 00:15:37,130 --> 00:15:40,430 Something just exists forever and always has existed. 301 00:15:40,430 --> 00:15:41,550 Those are your two choices. 302 00:15:41,550 --> 00:15:44,050 They're both uncomfortable. 303 00:15:44,050 --> 00:15:45,480 We have to live with one or the other. 304 00:15:45,480 --> 00:15:48,730 (DEEP LOW HUMMING) 305 00:15:54,690 --> 00:15:56,180 (COSMIC ROARING) 306 00:15:56,180 --> 00:15:59,130 - [Narrator] Infinity is thought to exist in our own 307 00:15:59,130 --> 00:16:01,770 universe inside the very strange phenomenon 308 00:16:01,770 --> 00:16:05,410 known as the black hole. 309 00:16:05,410 --> 00:16:08,050 A black hole is created when a star dies 310 00:16:08,050 --> 00:16:10,290 and collapses in on itself, creating 311 00:16:10,290 --> 00:16:14,370 a center of infinite density. 312 00:16:14,370 --> 00:16:16,810 Everything that gets close to the black hole 313 00:16:16,810 --> 00:16:21,490 gets sucked in and can never escape. 314 00:16:21,490 --> 00:16:24,810 These strange but common holes in space and time 315 00:16:24,810 --> 00:16:29,690 bend all dimensions, and any physical laws we understand 316 00:16:29,690 --> 00:16:33,850 do not apply at the center of a black hole. 317 00:16:33,850 --> 00:16:36,760 Black holes were discovered relatively recently 318 00:16:36,760 --> 00:16:41,030 and have been the fascination of physicists worldwide. 319 00:16:41,030 --> 00:16:43,260 - [Speaker 9] We actually have things that go to infinity 320 00:16:43,260 --> 00:16:44,260 in our own universe. 321 00:16:44,260 --> 00:16:45,360 So black holes. 322 00:16:45,360 --> 00:16:49,040 black holes are a singularity where a star or an object 323 00:16:49,040 --> 00:16:52,680 has collapsed in on itself, and gravity 324 00:16:52,680 --> 00:16:55,640 has increased and increased and increased 325 00:16:55,640 --> 00:16:57,360 as you go to the single singular 326 00:16:57,360 --> 00:16:59,440 point of the black hole. 327 00:16:59,440 --> 00:17:03,540 And at that very singular point, the level, 328 00:17:03,540 --> 00:17:06,010 the strength of gravity is infinite. 329 00:17:06,010 --> 00:17:08,660 (COSMIC ROARING) 330 00:17:08,660 --> 00:17:13,350 - [Narrator] So here we have proof that infinity exists. 331 00:17:13,350 --> 00:17:16,960 A proof of concept, albeit inside a huge black hole 332 00:17:16,960 --> 00:17:21,280 in space where we can never explore. 333 00:17:21,280 --> 00:17:23,880 How can we be sure that infinity truly 334 00:17:23,880 --> 00:17:27,330 exists within a black hole? 335 00:17:27,330 --> 00:17:29,400 - [Speaker 11] What we have in the universe are things which 336 00:17:29,400 --> 00:17:33,000 are consequences of physical laws, and black holes are 337 00:17:33,000 --> 00:17:34,950 consequences of physical laws. 338 00:17:34,950 --> 00:17:37,290 We know that you can create giant stars 339 00:17:37,290 --> 00:17:39,450 and we see giant stars in the universe. 340 00:17:39,450 --> 00:17:41,630 We know that giant stars die, right? 341 00:17:41,630 --> 00:17:44,550 They run out of fuel, their nuclear furnaces go out 342 00:17:44,550 --> 00:17:46,390 and these stars collapse. 343 00:17:46,390 --> 00:17:47,810 What happens when they collapse? 344 00:17:47,810 --> 00:17:51,130 Well, their mass starts to crash down and crash down, 345 00:17:51,130 --> 00:17:53,250 and using our best physical theories, 346 00:17:53,250 --> 00:17:55,910 we ask what happens to that mass, and it just keeps going, 347 00:17:55,910 --> 00:17:59,030 and it crashes down and forms a black hole. 348 00:17:59,030 --> 00:18:02,670 What's not understood is that region at the very center where 349 00:18:02,670 --> 00:18:05,790 things seem to go wrong, where we get our infinities, 350 00:18:05,790 --> 00:18:07,590 and that's the regime where we know 351 00:18:07,590 --> 00:18:12,100 we have to worry about quantum mechanics, as well as gravity. 352 00:18:12,100 --> 00:18:15,470 - [Narrator] So conceptually, there is infinity inside 353 00:18:15,470 --> 00:18:19,070 a black hole, in the same way as infinite 354 00:18:19,070 --> 00:18:24,230 density existed in the birth of our universe, the Big Bang. 355 00:18:24,230 --> 00:18:26,790 Again, we don't have the physics to date 356 00:18:26,790 --> 00:18:30,230 to explore these theoretical infinities, 357 00:18:30,230 --> 00:18:32,790 but we can accurately speculate as 358 00:18:32,790 --> 00:18:35,960 to the behaviors of an object falling into a black hole. 359 00:18:41,060 --> 00:18:45,210 - [Speaker 7] So black holes are a place where, 360 00:18:45,210 --> 00:18:50,160 you know, space and time as we know them come to an end. 361 00:18:52,930 --> 00:18:55,270 - [Speaker 4] Imagine we have a black hole here, 362 00:18:55,270 --> 00:18:57,250 and let's send anybody into this, 363 00:18:57,250 --> 00:18:59,600 and we're going to say, please signal us as you're falling. 364 00:18:59,600 --> 00:19:00,950 Beep-beep, beep-beep, beep-beep. 365 00:19:00,950 --> 00:19:02,050 And they're falling, falling. 366 00:19:02,050 --> 00:19:06,870 And then their beep-beep starting to beep, beep, beep. 367 00:19:06,870 --> 00:19:08,810 And their clocks are getting slower. 368 00:19:08,810 --> 00:19:10,490 You may have seen the movie "Interstellar," 369 00:19:10,490 --> 00:19:14,030 where one hour on the surface of this planet near the event 370 00:19:14,030 --> 00:19:15,910 horizon of a supermassive black hole, 371 00:19:15,910 --> 00:19:19,210 is equivalent to seven years on the spaceship that's orbiting, 372 00:19:19,210 --> 00:19:21,950 that's further away from the black hole. 373 00:19:21,950 --> 00:19:24,450 And, uh, similarly, when you fall into a black hole, 374 00:19:24,450 --> 00:19:26,070 your watch is-- you think, oh, it's just 375 00:19:26,070 --> 00:19:27,250 click, click, click, click. 376 00:19:27,250 --> 00:19:32,740 But viewed from the outside you're seeing beep, beep, beep. 377 00:19:32,740 --> 00:19:34,800 And then when you reach the event horizon, 378 00:19:34,800 --> 00:19:38,740 the black hole, then the person hangs there forever. 379 00:19:38,740 --> 00:19:41,360 From the outside, you cannot fall into a black hole, 380 00:19:41,360 --> 00:19:44,560 but from the viewpoint of that person, you go right into it. 381 00:19:44,560 --> 00:19:48,300 So there's a whole universe inside the event 382 00:19:48,300 --> 00:19:50,460 horizon of a black hole that is disconnected 383 00:19:50,460 --> 00:19:51,980 from our space time. 384 00:19:51,980 --> 00:19:54,320 But you can get to it, but you just can't go back. 385 00:19:54,320 --> 00:19:55,410 It's a one-way entrance. 386 00:19:59,190 --> 00:20:00,650 (COSMIC HUMMING) 387 00:20:00,650 --> 00:20:03,900 - [Speaker 7] When I was a kid, people often described just 388 00:20:03,900 --> 00:20:05,620 black holes as connecting to other 389 00:20:05,620 --> 00:20:10,660 universes or somehow being their own little universe. 390 00:20:10,660 --> 00:20:11,840 An interesting notion. 391 00:20:11,840 --> 00:20:14,980 There's a lot of similarities between the horizon 392 00:20:14,980 --> 00:20:16,800 of a black hole and for example, 393 00:20:16,800 --> 00:20:20,960 the horizon that allows us not to see beyond the universe. 394 00:20:24,600 --> 00:20:27,220 - [Narrator] Many speculations have been posited 395 00:20:27,220 --> 00:20:29,480 as to their purpose in the universe, 396 00:20:29,480 --> 00:20:31,410 and some have thought that they are the portals 397 00:20:31,410 --> 00:20:34,250 to other universes. 398 00:20:34,250 --> 00:20:36,930 Another speculation is that the center of a black hole 399 00:20:36,930 --> 00:20:43,330 creates a new Big Bang, which in turn creates a new universe. 400 00:20:43,330 --> 00:20:45,770 Whatever this bizarre phenomenon is, 401 00:20:45,770 --> 00:20:51,790 we can only speculate about the realities inside a black hole. 402 00:20:51,790 --> 00:20:53,290 - [Speaker 4] Could a black hole be 403 00:20:53,290 --> 00:20:55,530 the machine or process in our universe 404 00:20:55,530 --> 00:20:57,110 that creates another universe? 405 00:20:57,110 --> 00:20:59,170 And that could very well be the case. 406 00:20:59,170 --> 00:21:00,670 We have a big star. 407 00:21:00,670 --> 00:21:02,810 We know that stars more massive than let's say, about 408 00:21:02,810 --> 00:21:04,930 20 solar masses, they go boom. 409 00:21:04,930 --> 00:21:06,330 They don't-- they create a neutron 410 00:21:06,330 --> 00:21:07,790 star and then they create a black hole, 411 00:21:07,790 --> 00:21:09,050 if it's more massive. 412 00:21:09,050 --> 00:21:11,690 And that black hole, there it sits. 413 00:21:11,690 --> 00:21:13,370 And we know that inside of there 414 00:21:13,370 --> 00:21:14,750 is not part of our universe. 415 00:21:14,750 --> 00:21:16,090 We have no way of getting information 416 00:21:16,090 --> 00:21:18,250 from inside the black hole. 417 00:21:18,250 --> 00:21:19,610 That kind is like a free for all 418 00:21:19,610 --> 00:21:21,550 for a theoretical cosmologist to say, 419 00:21:21,550 --> 00:21:24,030 sure, there's a-- there's a whole universe in there. 420 00:21:24,030 --> 00:21:26,310 And matter of fact, my dead grandmother 421 00:21:26,310 --> 00:21:27,310 lives in there or something. 422 00:21:27,310 --> 00:21:28,770 You could invent all kinds of crazy things 423 00:21:28,770 --> 00:21:30,150 because it's kind of hidden away. 424 00:21:32,680 --> 00:21:34,400 We wave our hands an awful lot, try 425 00:21:34,400 --> 00:21:38,160 to be consistent with the physics we do know, but inside, 426 00:21:38,160 --> 00:21:41,870 whether we have a whole new universe, uh, sure, why not? 427 00:21:41,870 --> 00:21:48,870 (LAUGHS) 428 00:21:53,970 --> 00:21:55,600 - [Narrator] A new discovery has 429 00:21:55,600 --> 00:21:59,470 been made in the last 20 years that has science baffled. 430 00:21:59,470 --> 00:22:01,160 (MYSTERIOUS MUSIC) 431 00:22:01,160 --> 00:22:05,520 Everything that we knew of in the universe amounts to only 5% 432 00:22:05,520 --> 00:22:11,760 of everything that there is, leaving a massive 95% of space 433 00:22:11,760 --> 00:22:14,720 unaccounted for. 434 00:22:14,720 --> 00:22:16,680 We now know that space is made up 435 00:22:16,680 --> 00:22:19,960 of two unknown, undefined elements named 436 00:22:19,960 --> 00:22:23,200 dark energy and dark matter. 437 00:22:23,200 --> 00:22:29,520 Dark energy being the most recent discovery in only 1998. 438 00:22:29,520 --> 00:22:32,000 We know they exist because of the effects 439 00:22:32,000 --> 00:22:34,000 that they exert on the universe, 440 00:22:34,000 --> 00:22:38,120 but we can't see or understand their properties. 441 00:22:38,120 --> 00:22:41,960 Dark energy is known to repel the stuff of the universe, 442 00:22:41,960 --> 00:22:45,190 while dark matter is thought to bind galaxies together. 443 00:22:47,720 --> 00:22:52,240 These two elements are thought to make up 95% of everything 444 00:22:52,240 --> 00:22:56,780 in the universe, and we have no idea as to what they are. 445 00:23:02,990 --> 00:23:04,800 - [Speaker 6] We have these two big mysteries 446 00:23:04,800 --> 00:23:06,160 in the universe at the moment. 447 00:23:06,160 --> 00:23:08,020 One is dark matter. 448 00:23:08,020 --> 00:23:10,880 There's something that's binding galaxies and clusters 449 00:23:10,880 --> 00:23:14,900 together at some particle that we don't know about, 450 00:23:14,900 --> 00:23:19,300 but in various supersymmetric theories and so on you can see, 451 00:23:19,300 --> 00:23:20,820 yeah, there's room for particles like that. 452 00:23:20,820 --> 00:23:22,140 We'll probably find them eventually, 453 00:23:22,140 --> 00:23:24,200 and then we'll understand what dark matter is. 454 00:23:24,200 --> 00:23:26,810 And then there's dark energy, which is something else again, 455 00:23:26,810 --> 00:23:29,010 and that's to do with the structure of space and time. 456 00:23:29,010 --> 00:23:30,950 There is something in our universe 457 00:23:30,950 --> 00:23:33,430 which is making the universe accelerate. 458 00:23:33,430 --> 00:23:35,530 And we call it dark energy-- it sounds like we know what it is. 459 00:23:35,530 --> 00:23:36,530 We don't. 460 00:23:36,530 --> 00:23:37,870 No-- we haven't got the foggiest idea 461 00:23:37,870 --> 00:23:39,910 what dark energy is. 462 00:23:39,910 --> 00:23:43,390 Current dark energy is not really a good name 463 00:23:43,390 --> 00:23:44,410 because it's saying-- 464 00:23:44,410 --> 00:23:46,730 it's asserting that we know it's a sort of energy. 465 00:23:46,730 --> 00:23:47,830 We don't even know that. 466 00:23:47,830 --> 00:23:50,070 All we have is an observational effect. 467 00:23:50,070 --> 00:23:53,210 There is something that is making the universe accelerate. 468 00:23:56,610 --> 00:23:59,990 - [Speaker 9] Our universe has grown over the 13.8 billion 469 00:23:59,990 --> 00:24:03,910 years, so much and so fast, that light from 470 00:24:03,910 --> 00:24:06,310 the furthest objects in the universe 471 00:24:06,310 --> 00:24:08,790 can never actually catch up. 472 00:24:08,790 --> 00:24:11,770 So if we have the universe growing like this, 473 00:24:11,770 --> 00:24:16,630 and we have a galaxy over here, well, the universe is growing 474 00:24:16,630 --> 00:24:19,910 and so this light is never going to catch up. 475 00:24:19,910 --> 00:24:21,910 And this is essentially a consequence of something 476 00:24:21,910 --> 00:24:24,810 called dark energy. 477 00:24:24,810 --> 00:24:28,540 - [Speaker 12] We now have been able to detect things like dark 478 00:24:28,540 --> 00:24:31,840 energy, which we only see by their gravitational influence, 479 00:24:31,840 --> 00:24:33,640 so we don't feel it on our hands. 480 00:24:33,640 --> 00:24:36,460 We can't see it with our eyes, but what we can see 481 00:24:36,460 --> 00:24:41,500 is it moving around the things around us. 482 00:24:41,500 --> 00:24:44,340 The analogy I make is with the wind. 483 00:24:44,340 --> 00:24:47,060 We can't see the wind, but we can see the wind pushing 484 00:24:47,060 --> 00:24:49,540 around the leaves of trees. 485 00:24:49,540 --> 00:24:52,140 Now, it's remarkable to think that just 200 years ago, we 486 00:24:52,140 --> 00:24:54,020 didn't know what the wind was. 487 00:24:54,020 --> 00:24:55,840 We didn't have a particle theory of matter. 488 00:24:55,840 --> 00:24:57,240 We didn't have the periodic table. 489 00:24:57,240 --> 00:25:00,120 We didn't know what carbon and oxygen and nitrogen were. 490 00:25:00,120 --> 00:25:03,300 - [Speaker 6] And right now we've got no 491 00:25:03,300 --> 00:25:05,420 really good way of pinning down what 492 00:25:05,420 --> 00:25:07,180 is causing that dark energy. 493 00:25:07,180 --> 00:25:08,900 So there's a few ideas knocking around. 494 00:25:08,900 --> 00:25:11,200 There's a few tests that people are proposing. 495 00:25:11,200 --> 00:25:12,540 There's a lot of people planning 496 00:25:12,540 --> 00:25:15,720 experiments to test those ideas over the next decade or so. 497 00:25:15,720 --> 00:25:17,420 - [Speaker 12] Maybe it will take us another couple 498 00:25:17,420 --> 00:25:19,500 of hundred years, but maybe we'll find out that 499 00:25:19,500 --> 00:25:20,780 there's a whole dark matter chemistry 500 00:25:20,780 --> 00:25:23,960 going on out there that we, uh, have yet to understand. 501 00:25:26,680 --> 00:25:30,300 - [Speaker 5] A few decades ago, the actual extent, 502 00:25:30,300 --> 00:25:33,060 what we thought of as the entirety of the universe, 503 00:25:33,060 --> 00:25:35,760 is now resigned to just 5%. 504 00:25:35,760 --> 00:25:38,440 So that is the atoms, other types of particles 505 00:25:38,440 --> 00:25:41,060 in our standard model. 506 00:25:41,060 --> 00:25:44,460 We have once again undergone this revolution 507 00:25:44,460 --> 00:25:45,860 in our understanding of our place 508 00:25:45,860 --> 00:25:49,020 and really relegated us to a-- 509 00:25:49,020 --> 00:25:51,120 an afterthought, a very interesting, very diverse, 510 00:25:51,120 --> 00:25:54,380 very complex afterthought, but really fundamentally 511 00:25:54,380 --> 00:25:57,380 the universe with a five cents on the dollar, 512 00:25:57,380 --> 00:25:59,870 the bits that make up you and I and all of the stars. 513 00:26:04,060 --> 00:26:06,960 (EXPLOSION) 514 00:26:08,890 --> 00:26:11,380 - [Narrator] Our universe is thought to have burst 515 00:26:11,380 --> 00:26:15,100 into existence 13.8 billion years ago 516 00:26:15,100 --> 00:26:19,100 from basically nothing, no matter 517 00:26:19,100 --> 00:26:23,650 time or space existed before. 518 00:26:23,650 --> 00:26:25,610 But a new theory is emerging that is 519 00:26:25,610 --> 00:26:27,370 gaining more and more acceptance 520 00:26:27,370 --> 00:26:30,730 and is based on solid physics. 521 00:26:30,730 --> 00:26:32,890 It is the theory that our universe is one 522 00:26:32,890 --> 00:26:34,560 of many infinite universes. 523 00:26:34,560 --> 00:26:37,130 (ENIGMATIC MUSIC) 524 00:26:37,130 --> 00:26:39,810 It is thought that these universes may be completely 525 00:26:39,810 --> 00:26:43,010 disconnected from each other, and may have vastly different 526 00:26:43,010 --> 00:26:44,610 properties or dimensions. 527 00:26:47,340 --> 00:26:50,530 - [Speaker 11] The multiverse theory is that our universe is 528 00:26:50,530 --> 00:26:54,210 not alone, that there are a multitude of different 529 00:26:54,210 --> 00:26:57,960 universes out there, hidden in some higher dimensional sort 530 00:26:57,960 --> 00:27:01,170 of space time, and we're just one of almost infinite 531 00:27:01,170 --> 00:27:02,490 number of other universes. 532 00:27:05,010 --> 00:27:08,890 - [Speaker 1] But this idea of infinite universes, 533 00:27:08,890 --> 00:27:11,870 I think is really exciting to contemplate, 534 00:27:11,870 --> 00:27:15,930 and I don't know if we'll find the answer in my lifetime 535 00:27:15,930 --> 00:27:18,890 or not, but I'm very excited about more 536 00:27:18,890 --> 00:27:21,050 people exploring the idea. 537 00:27:21,050 --> 00:27:24,000 - [Speaker 2] Multiverses are both heartening to me 538 00:27:24,000 --> 00:27:26,280 and disappointing because we're just 539 00:27:26,280 --> 00:27:30,880 one of the universe's in an infinite number. 540 00:27:30,880 --> 00:27:33,370 But if there are an infinite number of universes, 541 00:27:33,370 --> 00:27:34,840 that means that there are an infinite number 542 00:27:34,840 --> 00:27:38,800 of possibilities that anything and everything exists. 543 00:27:38,800 --> 00:27:43,360 And that idea is heartening. 544 00:27:43,360 --> 00:27:45,080 - [Narrator] Infinity is already 545 00:27:45,080 --> 00:27:47,440 a concept that is stretching our understanding 546 00:27:47,440 --> 00:27:48,920 to the limits. 547 00:27:48,920 --> 00:27:52,920 But an infinite universe and infinitely many infinite 548 00:27:52,920 --> 00:27:57,280 universes is clearly beyond our science. 549 00:27:57,280 --> 00:27:59,880 What are the possible models or variations 550 00:27:59,880 --> 00:28:04,260 of the multiverse that have been contemplated to date? 551 00:28:04,260 --> 00:28:06,800 - [Speaker 13] I think today a popular 552 00:28:06,800 --> 00:28:11,080 model is that our universe is one amongst many. 553 00:28:11,080 --> 00:28:12,960 If you think of soap bubbles in the sink 554 00:28:12,960 --> 00:28:15,080 when you're washing up in the morning, 555 00:28:15,080 --> 00:28:16,760 you see thousands of soap bubbles 556 00:28:16,760 --> 00:28:19,160 all interlocked and some bubbles are big 557 00:28:19,160 --> 00:28:22,600 and some bubbles are small, and some bubbles are getting bigger 558 00:28:22,600 --> 00:28:24,640 and other bubbles are shrinking. 559 00:28:24,640 --> 00:28:26,200 People think of the universe, maybe 560 00:28:26,200 --> 00:28:29,680 in the same way, that we-- we are one bubble in a very 561 00:28:29,680 --> 00:28:32,240 complex multi-bubble universe. 562 00:28:32,240 --> 00:28:35,880 So our bubble is huge and expanding, 563 00:28:35,880 --> 00:28:36,900 and we know it's expanding. 564 00:28:36,900 --> 00:28:39,360 We even know it's accelerating bubble from work that was done 565 00:28:39,360 --> 00:28:42,040 here in Australia in the 90s. 566 00:28:42,040 --> 00:28:43,640 And so there'll be other bubbles that 567 00:28:43,640 --> 00:28:45,600 may be also expanding near US and other bubbles 568 00:28:45,600 --> 00:28:46,740 that may be shrinking. 569 00:28:46,740 --> 00:28:48,760 So I think people would say that the universe is probably 570 00:28:48,760 --> 00:28:50,940 finite in terms of our universe, 571 00:28:50,940 --> 00:28:52,600 but there are many other universe bubbles 572 00:28:52,600 --> 00:28:55,000 expanding and contracting that go on and on for 573 00:28:55,000 --> 00:28:56,510 presumably forever. 574 00:29:01,080 --> 00:29:03,440 - [Narrator] Another possibility is that other 575 00:29:03,440 --> 00:29:06,660 universes exist alongside our own universe, 576 00:29:06,660 --> 00:29:08,840 but in different dimensions to our three 577 00:29:08,840 --> 00:29:12,610 of space and one of time. 578 00:29:12,610 --> 00:29:16,910 - [Speaker 7] It is possible to have an infinite universe 579 00:29:16,910 --> 00:29:20,630 that is itself embedded in an infinite 580 00:29:20,630 --> 00:29:22,750 sea of infinite universes. 581 00:29:22,750 --> 00:29:26,790 That is all possible, and it seems counterintuitive, 582 00:29:26,790 --> 00:29:29,610 but the universe, if you want to think of it, 583 00:29:29,610 --> 00:29:31,990 just basically imagine our universe 584 00:29:31,990 --> 00:29:35,050 is embedded not in four dimensions, in five dimensions. 585 00:29:35,050 --> 00:29:38,830 So our universe is infinite in those four dimensions, 586 00:29:38,830 --> 00:29:41,190 but then another one is just next door 587 00:29:41,190 --> 00:29:43,270 in the fifth dimension, and again, it's 588 00:29:43,270 --> 00:29:44,850 infinite in its dimensions. 589 00:29:44,850 --> 00:29:46,930 Now, I'm not saying that's the way the universe is, 590 00:29:46,930 --> 00:29:50,350 but that illustrates the possibility of having 591 00:29:50,350 --> 00:29:52,470 an infinite number of universes, 592 00:29:52,470 --> 00:29:58,990 each infinite separated, just need an extra dimension. 593 00:29:59,990 --> 00:30:01,150 - [Speaker 11] When you talk about something like 594 00:30:01,150 --> 00:30:04,150 a multiverse, you could be talking about universes like 595 00:30:04,150 --> 00:30:06,130 our own, which have four dimensions, 596 00:30:06,130 --> 00:30:08,590 three of space and one of time, but embedded 597 00:30:08,590 --> 00:30:10,210 in a higher dimensional space. 598 00:30:10,210 --> 00:30:12,030 So each of those individual universes 599 00:30:12,030 --> 00:30:16,590 could be spatially infinite inside a large volume. 600 00:30:19,560 --> 00:30:22,660 - [Narrator] There is a new theory that universes 601 00:30:22,660 --> 00:30:27,580 are suspended in an even larger structure made up of membranes. 602 00:30:27,580 --> 00:30:33,200 These are known as branes, and they contain universes. 603 00:30:33,200 --> 00:30:36,020 - [Speaker 9] Some very compelling theories, which I-- 604 00:30:36,020 --> 00:30:37,860 I personally believe suggest that there 605 00:30:37,860 --> 00:30:40,440 could be a larger framework, something called a brane. 606 00:30:40,440 --> 00:30:44,180 So a brane, not this brain-- um, 607 00:30:44,180 --> 00:30:47,580 that says there's billions of universes, which each have 608 00:30:47,580 --> 00:30:49,580 billions of galaxies, which each have billions 609 00:30:49,580 --> 00:30:51,140 of stars and planets and planets 610 00:30:51,140 --> 00:30:53,980 and so on and so on and so on. 611 00:30:53,980 --> 00:30:56,460 But then there's no reason to think, well, that brain is 612 00:30:56,460 --> 00:30:58,220 actually a part of a larger framework 613 00:30:58,220 --> 00:31:02,560 called a blaa, which each has billions of brains, 614 00:31:02,560 --> 00:31:03,820 which each have billions of universes 615 00:31:03,820 --> 00:31:04,840 and billions of galaxies. 616 00:31:04,840 --> 00:31:07,470 And so there's always going to be something bigger. 617 00:31:07,470 --> 00:31:10,720 (DEEP SPACE RUMBLING) 618 00:31:12,200 --> 00:31:16,450 - [Narrator] And infinitely many infinite universes makes 619 00:31:16,450 --> 00:31:18,690 everything that could happen happen 620 00:31:18,690 --> 00:31:22,050 an infinite number of times. 621 00:31:22,050 --> 00:31:25,710 This is the many worlds theory, which leads to conclusions 622 00:31:25,710 --> 00:31:30,570 as wild as we all have infinite copies of ourselves living 623 00:31:30,570 --> 00:31:34,210 in infinitely many universes, each with the same 624 00:31:34,210 --> 00:31:37,450 or vastly different outcomes. 625 00:31:37,450 --> 00:31:39,490 Sounds crazy? 626 00:31:39,490 --> 00:31:41,770 Not according to physicists who have 627 00:31:41,770 --> 00:31:45,180 proposed this very outcome. 628 00:31:45,180 --> 00:31:48,050 - [Speaker 2] It wouldn't surprise me if there were 629 00:31:48,050 --> 00:31:50,970 infinite multiverses, an infinite number 630 00:31:50,970 --> 00:31:52,850 of reproductions of Earth and of us 631 00:31:52,850 --> 00:31:56,100 and somewhere Elvis lived. 632 00:31:56,100 --> 00:31:57,540 (DISTANT SHOUTING) 633 00:31:57,540 --> 00:32:00,880 (DISTANT MUSIC PLAYING) 634 00:32:02,230 --> 00:32:05,010 - [Speaker 9] There is probably something having an identical 635 00:32:05,010 --> 00:32:07,980 conversation right now in at least one of hundreds 636 00:32:07,980 --> 00:32:11,190 billion worlds, I would say. 637 00:32:11,190 --> 00:32:13,690 - [Speaker 6] Everything that could conceivably happen, might 638 00:32:13,690 --> 00:32:16,330 happen in some other universe. 639 00:32:16,330 --> 00:32:20,390 I-- I love it because every mistake I've made in my life, 640 00:32:20,390 --> 00:32:21,800 there's some other universe where Reynolds 641 00:32:21,800 --> 00:32:22,800 has made the right decision. 642 00:32:26,930 --> 00:32:29,410 - [Speaker 14] The sort of theories that are proposed 643 00:32:29,410 --> 00:32:32,650 about possible multiple universes where we're all 644 00:32:32,650 --> 00:32:34,890 actually existing in some slightly different form, 645 00:32:34,890 --> 00:32:35,890 and so on. 646 00:32:35,890 --> 00:32:40,430 I mean, they all sound counterintuitive in a sense. 647 00:32:40,430 --> 00:32:44,130 They almost sound crazy, but they're 648 00:32:44,130 --> 00:32:47,170 not being promoted as just some sort of crazy idea. 649 00:32:47,170 --> 00:32:52,090 They are the consequences of analysis of the physics. 650 00:32:52,090 --> 00:32:55,630 And I guess I would just say, well, you know, maybe. 651 00:33:01,550 --> 00:33:03,870 - [Speaker 15] Why do we get infinite copies of things? 652 00:33:03,870 --> 00:33:06,330 Well, basically because quantum mechanics 653 00:33:06,330 --> 00:33:08,850 says that anything can happen. 654 00:33:08,850 --> 00:33:11,720 So if you have a bit of the universe that 655 00:33:11,720 --> 00:33:13,760 looks like our bit, well, there's 656 00:33:13,760 --> 00:33:15,220 nothing special about that. 657 00:33:15,220 --> 00:33:17,860 So that bit of the universe, if you just wait long enough, 658 00:33:17,860 --> 00:33:18,900 will be duplicated. 659 00:33:18,900 --> 00:33:21,240 Very, very low probability, but if you have an infinite amount 660 00:33:21,240 --> 00:33:22,840 of time to wait, then everything that's possible 661 00:33:22,840 --> 00:33:23,840 will happen. 662 00:33:23,840 --> 00:33:27,780 You'll win the lottery, you'll lose the lottery. 663 00:33:27,780 --> 00:33:31,680 - [Speaker 16] And so the idea is that since each of us is 664 00:33:31,680 --> 00:33:34,920 composed of a finite number of atoms, 665 00:33:34,920 --> 00:33:38,720 and these atoms have large but finite number 666 00:33:38,720 --> 00:33:42,200 of configurations, that if you have infinite 667 00:33:42,200 --> 00:33:45,200 number of universes, that the same 668 00:33:45,200 --> 00:33:48,080 configuration exists there. 669 00:33:48,080 --> 00:33:51,160 And so this is the idea of having copies, which could be 670 00:33:51,160 --> 00:33:53,760 slightly different or even identical 671 00:33:53,760 --> 00:33:56,760 if the multiverse exists. 672 00:33:56,760 --> 00:33:58,400 - [Speaker 15] You kind of live forever 673 00:33:58,400 --> 00:34:00,880 because there's always a finite chance that whatever 674 00:34:00,880 --> 00:34:02,180 kills you didn't happen. 675 00:34:02,180 --> 00:34:04,940 Now, that will get rarer and rarer and rarer, 676 00:34:04,940 --> 00:34:06,040 and the chances that you're going 677 00:34:06,040 --> 00:34:08,280 to be the one that lives forever gets less 678 00:34:08,280 --> 00:34:09,940 and less likely each time. 679 00:34:09,940 --> 00:34:12,090 But it's still logically possible, 680 00:34:12,090 --> 00:34:13,940 and everything that's essentially logically 681 00:34:13,940 --> 00:34:15,710 and physically possible will happen 682 00:34:15,710 --> 00:34:17,750 in this vast, large universe. 683 00:34:17,750 --> 00:34:19,710 Once things are infinitely large, 684 00:34:19,710 --> 00:34:22,130 it doesn't only seem possible, it seems inevitable. 685 00:34:24,890 --> 00:34:27,310 - [Speaker 11] So if there are an infinite number of other 686 00:34:27,310 --> 00:34:30,340 universes, then of course, an infinite number of them will, 687 00:34:30,340 --> 00:34:32,420 uh, be dead, but also an infinite 688 00:34:32,420 --> 00:34:33,530 number of them will be alive. 689 00:34:33,530 --> 00:34:35,790 But then you're playing games with infinities, right? 690 00:34:35,790 --> 00:34:37,480 Which is what you can do with infinities. 691 00:34:40,070 --> 00:34:41,710 - [Narrator] And playing games with 692 00:34:41,710 --> 00:34:44,420 infinities is as mind-blowing as any 693 00:34:44,420 --> 00:34:46,830 game we could conceive of. 694 00:34:46,830 --> 00:34:50,450 The following bears testament to this. 695 00:34:50,450 --> 00:34:53,630 - [Speaker 2] If you have infinite possibilities, 696 00:34:53,630 --> 00:34:55,270 then surely one of those possibilities 697 00:34:55,270 --> 00:34:56,750 is a universe in which other infinite 698 00:34:56,750 --> 00:34:59,630 universes cannot occur. 699 00:34:59,630 --> 00:35:02,710 And if our universe exists, then it 700 00:35:02,710 --> 00:35:05,630 must mean that our universe is that universe that excludes 701 00:35:05,630 --> 00:35:08,650 all other infinite universes. 702 00:35:08,650 --> 00:35:11,270 - [Narrator] Concepts like these are not easy to get 703 00:35:11,270 --> 00:35:14,150 your head around, and neither is the idea that 704 00:35:14,150 --> 00:35:15,750 every history event has happened 705 00:35:15,750 --> 00:35:18,190 in an infinite number of ways. 706 00:35:18,190 --> 00:35:20,060 (EXPLOSION) 707 00:35:20,060 --> 00:35:22,800 (OMINOUS MUSIC) 708 00:35:23,800 --> 00:35:25,990 - [Speaker 11] There are infinite numbers of identical 709 00:35:25,990 --> 00:35:28,470 patches, and in those identical patches, 710 00:35:28,470 --> 00:35:31,050 the history of the universe gets played out identically, 711 00:35:31,050 --> 00:35:32,890 and that there would be a patch, in fact, 712 00:35:32,890 --> 00:35:35,150 an infinite number of patches where we're having this 713 00:35:35,150 --> 00:35:36,910 conversation, plus an infinite number 714 00:35:36,910 --> 00:35:38,270 of patches where we're not. 715 00:35:38,270 --> 00:35:41,010 An infinite number of patches, where the lights are on, 716 00:35:41,010 --> 00:35:42,470 and an infinite number of patches 717 00:35:42,470 --> 00:35:43,670 where the lights are off or you're 718 00:35:43,670 --> 00:35:46,350 talking to somebody else. 719 00:35:46,350 --> 00:35:49,390 - [Narrator] The multi-world theory is understandably 720 00:35:49,390 --> 00:35:52,470 a controversial one, so much so that some people 721 00:35:52,470 --> 00:35:55,580 dismiss the whole concept. 722 00:35:55,580 --> 00:35:57,270 - [Speaker 15] These questions about 723 00:35:57,270 --> 00:35:59,850 infinite copies of things do trouble people, 724 00:35:59,850 --> 00:36:01,340 and I think rightly so. 725 00:36:01,340 --> 00:36:02,890 Uh, so some people say, you know what? 726 00:36:02,890 --> 00:36:05,150 It is sufficiently troubling that I want the universe 727 00:36:05,150 --> 00:36:07,620 to, like, be pretty small, because then 728 00:36:07,620 --> 00:36:09,880 you can get away without having copies of things. 729 00:36:09,880 --> 00:36:11,220 But I think a lot of other people 730 00:36:11,220 --> 00:36:14,780 like the excitement of-- of having infinite amount of stuff 731 00:36:14,780 --> 00:36:16,360 in the universe, makes everything possible. 732 00:36:16,360 --> 00:36:19,570 And if everything's possible, that's kind of fun. 733 00:36:19,570 --> 00:36:22,820 - [Speaker 9] I think it is very possible that within 734 00:36:22,820 --> 00:36:25,860 the next century, we will have a good understanding 735 00:36:25,860 --> 00:36:28,220 or evidence that multiverses are really 736 00:36:28,220 --> 00:36:30,660 true in some way or another. 737 00:36:30,660 --> 00:36:34,380 I think our universe is too big to be that boring 738 00:36:34,380 --> 00:36:36,800 and just have one universe. 739 00:36:36,800 --> 00:36:39,020 - [Narrator] Speculations are endless 740 00:36:39,020 --> 00:36:43,740 when it comes to such enormous concepts such as multiverses. 741 00:36:43,740 --> 00:36:45,300 But where does that lead us when 742 00:36:45,300 --> 00:36:49,710 it comes to our own possible infinite universe? 743 00:36:49,710 --> 00:36:52,140 - [Speaker 6] It makes the problem of infinity even worse 744 00:36:52,140 --> 00:36:55,340 that not only do you have to think of our three dimensions, 745 00:36:55,340 --> 00:36:57,460 but you think, well, there might actually be an infinite 746 00:36:57,460 --> 00:36:59,840 number of other universes. 747 00:36:59,840 --> 00:37:02,680 Maybe there's other infinities going off in other dimensions, 748 00:37:02,680 --> 00:37:04,860 and you have to contend with those as well. 749 00:37:04,860 --> 00:37:09,170 So the multiverse makes our problem of conceiving 750 00:37:09,170 --> 00:37:11,130 infinity even worse. 751 00:37:11,130 --> 00:37:12,600 It doesn't help. (LAUGHS) 752 00:37:12,600 --> 00:37:15,340 (CALM MUSIC) 753 00:37:15,340 --> 00:37:18,890 - [Narrator] Our universe consists of four dimensions, 754 00:37:18,890 --> 00:37:22,170 three of space and one of Time. 755 00:37:22,170 --> 00:37:24,490 Is it possible that other dimensions exist 756 00:37:24,490 --> 00:37:26,350 and we are blissfully unaware? 757 00:37:29,090 --> 00:37:32,890 Imagine sitting in a quiet room and all that you hear 758 00:37:32,890 --> 00:37:36,170 is the faint bird sound around you. 759 00:37:36,170 --> 00:37:41,290 But imagine the mass of radio, cell phone and TV signals that 760 00:37:41,290 --> 00:37:45,050 are passing through your body constantly 761 00:37:45,050 --> 00:37:47,370 until you have a radio or TV tuned 762 00:37:47,370 --> 00:37:50,090 into the correct frequency. 763 00:37:50,090 --> 00:37:53,210 Then you would have no idea of these TV, radio 764 00:37:53,210 --> 00:37:55,290 programs or conversations that are 765 00:37:55,290 --> 00:37:57,010 being constantly communicated. 766 00:38:00,450 --> 00:38:03,690 Perhaps there are other entities that are coexisting 767 00:38:03,690 --> 00:38:07,360 that are on completely different dimension to us, 768 00:38:07,360 --> 00:38:09,840 and their existence and conversations 769 00:38:09,840 --> 00:38:13,120 are as silent as the TV signals and radio that 770 00:38:13,120 --> 00:38:14,700 pass through us constantly. 771 00:38:21,440 --> 00:38:24,920 Dimensions could be of such a vastly different nature 772 00:38:24,920 --> 00:38:28,100 or scale that we may never, as humans, 773 00:38:28,100 --> 00:38:29,760 know or understand their existence. 774 00:38:29,760 --> 00:38:32,880 (MYSTERIOUS MUSIC) 775 00:38:32,880 --> 00:38:35,320 - [Speaker 17] Are there even more dimensions beyond 776 00:38:35,320 --> 00:38:36,570 what we imagine already? 777 00:38:36,570 --> 00:38:38,900 Erm, I wouldn't be surprised. 778 00:38:38,900 --> 00:38:41,270 In fact, I'd almost be surprised if they weren't. 779 00:38:41,270 --> 00:38:44,380 - [Speaker 18] The possibilities are all there, 780 00:38:44,380 --> 00:38:47,800 so they can exist in different dimensions 781 00:38:47,800 --> 00:38:48,870 all at the same time. 782 00:38:51,490 --> 00:38:54,120 - [Narrator] Are dimensions simply different versions 783 00:38:54,120 --> 00:38:57,200 of reality that don't interact with us and we 784 00:38:57,200 --> 00:38:59,540 can't interact with them? 785 00:38:59,540 --> 00:39:01,000 - [Speaker 2] You could conjecture 786 00:39:01,000 --> 00:39:04,820 any kind of reality where things don't interact with us. 787 00:39:04,820 --> 00:39:08,720 But it's that if they're not interacting with us, then 788 00:39:08,720 --> 00:39:12,370 it doesn't matter if they're in our world or not. 789 00:39:12,370 --> 00:39:15,600 - [Narrator] However, science is taking the idea of other 790 00:39:15,600 --> 00:39:18,620 dimensions very seriously. 791 00:39:18,620 --> 00:39:21,360 - [Speaker 9] It's nice to think that there could be other 792 00:39:21,360 --> 00:39:26,240 dimensions, and there could be 11 or 12, or however 793 00:39:26,240 --> 00:39:27,880 you want to throw out there. 794 00:39:27,880 --> 00:39:29,600 They very well could exist, and we just 795 00:39:29,600 --> 00:39:31,840 don't realize we're interacting with them 796 00:39:31,840 --> 00:39:33,940 or we haven't figured out how to interact with them. 797 00:39:33,940 --> 00:39:36,740 That's all very true. 798 00:39:36,740 --> 00:39:39,400 - [Narrator] How can we learn more about these 799 00:39:39,400 --> 00:39:43,110 possible other dimensions? 800 00:39:43,110 --> 00:39:45,640 - [Speaker 5] It is mainstream physics to talk 801 00:39:45,640 --> 00:39:47,260 about extra dimensions. 802 00:39:47,260 --> 00:39:50,140 Now, those dimensions can be very small. 803 00:39:50,140 --> 00:39:53,760 They can be wrapped, um, up on themselves essentially. 804 00:39:53,760 --> 00:39:54,960 And that can be of such small scales 805 00:39:54,960 --> 00:39:56,520 that you miss it, that essentially 806 00:39:56,520 --> 00:39:59,240 your hand just passes over and around 807 00:39:59,240 --> 00:40:03,660 this wrapped up dimension. 808 00:40:03,660 --> 00:40:06,030 - [Speaker 12] Extra dimensions are a very serious thing 809 00:40:06,030 --> 00:40:08,550 that's being considered in physics as a possible 810 00:40:08,550 --> 00:40:11,230 explanation for the fundamentals underlying 811 00:40:11,230 --> 00:40:14,700 what we were observing. 812 00:40:14,700 --> 00:40:18,030 - [Narrator] One of science's challenges is understanding 813 00:40:18,030 --> 00:40:23,030 gravity and why it is so weak compared to the other forces. 814 00:40:23,030 --> 00:40:28,690 Could other dimensions explain the gravity anomaly? 815 00:40:28,690 --> 00:40:32,230 - [Speaker 12] Extra dimensions come up as a way to possibly 816 00:40:32,230 --> 00:40:37,270 explain some really interesting physical conundrums, 817 00:40:37,270 --> 00:40:40,310 like trying to link quantum physics and gravity. 818 00:40:40,310 --> 00:40:42,790 People in, uh, the string theory fields 819 00:40:42,790 --> 00:40:44,870 are using extra dimensions to try 820 00:40:44,870 --> 00:40:48,010 to explain the nature of space and time, 821 00:40:48,010 --> 00:40:50,990 so it is genuinely possible that there's other dimensions 822 00:40:50,990 --> 00:40:55,190 that are out there that are either just too small for us 823 00:40:55,190 --> 00:40:59,830 to experience or too large, and we don't have access to them. 824 00:40:59,830 --> 00:41:03,960 So we live in a three dimensions of space world, 825 00:41:03,960 --> 00:41:06,940 but maybe there are other dimensions that are experienced 826 00:41:06,940 --> 00:41:10,860 by the particles that carry gravity, and maybe the charges 827 00:41:10,860 --> 00:41:12,700 that particles have are determined 828 00:41:12,700 --> 00:41:17,500 by the sizes of extra dimensions that they can see. 829 00:41:17,500 --> 00:41:19,500 - [Speaker 5] Certain theories suggest that gravity can have 830 00:41:19,500 --> 00:41:22,440 a wander through these dimensions, 831 00:41:22,440 --> 00:41:25,400 and then come back into our four dimension, 832 00:41:25,400 --> 00:41:28,420 and hence explain why it's so surprisingly weak 833 00:41:28,420 --> 00:41:31,540 relative to the other forces. 834 00:41:31,540 --> 00:41:33,540 There is the exact opposite scale, where 835 00:41:33,540 --> 00:41:36,660 you have larger dimensions. 836 00:41:36,660 --> 00:41:40,180 And in the same way that our universe, our four dimensions, 837 00:41:40,180 --> 00:41:46,180 could indeed be the surface layer of a larger bulk, so 838 00:41:46,180 --> 00:41:49,960 we are the membrane or the brain around a larger bulk, 839 00:41:49,960 --> 00:41:55,100 just as a two-dimensional surface of a balloon 840 00:41:55,100 --> 00:41:58,040 is encompassing this larger third dimension. 841 00:42:02,450 --> 00:42:05,100 - [Narrator] Dimensions could explain a lot about 842 00:42:05,100 --> 00:42:08,200 the things in our universe that at this stage, 843 00:42:08,200 --> 00:42:11,460 simply don't add up. 844 00:42:11,460 --> 00:42:14,260 Another mystery of our universe is how the ingredients 845 00:42:14,260 --> 00:42:16,420 of our universe had to be incredibly 846 00:42:16,420 --> 00:42:22,040 fine tuned for everything that we know to come into existence. 847 00:42:22,040 --> 00:42:25,820 - [Speaker 19] She tasted the porridge in the big bowl, 848 00:42:25,820 --> 00:42:28,060 but it was too hot. 849 00:42:28,060 --> 00:42:31,980 She tasted the porridge in the middle sized bowl, 850 00:42:31,980 --> 00:42:34,460 but it was too cold. 851 00:42:34,460 --> 00:42:38,500 She tasted the porridge in the wee little bowl. 852 00:42:38,500 --> 00:42:39,750 It was just right. 853 00:42:42,970 --> 00:42:47,340 - [Narrator] Our world is in the so-called Goldilocks zone, 854 00:42:47,340 --> 00:42:49,550 just right to support life. 855 00:42:49,550 --> 00:42:52,140 (ENIGMATIC MUSIC) 856 00:42:52,140 --> 00:42:55,280 Had things been even the tiniest bit different, 857 00:42:55,280 --> 00:43:00,840 nothing would exist, stars, planets, or us. 858 00:43:05,570 --> 00:43:08,810 This fine tuning has been compared to the likelihood 859 00:43:08,810 --> 00:43:11,210 of a storm blowing through a junkyard 860 00:43:11,210 --> 00:43:18,210 and producing the space shuttle, 861 00:43:19,270 --> 00:43:24,130 or a golfer who gets a hole in one every single time 862 00:43:24,130 --> 00:43:26,260 for his entire life. 863 00:43:32,050 --> 00:43:36,290 Our world is in the so-called Goldilocks zone, 864 00:43:36,290 --> 00:43:40,330 just right to support life. 865 00:43:40,330 --> 00:43:43,850 Is this fine tuning a pure random coincidence? 866 00:43:43,850 --> 00:43:48,140 Or is this a common outcome in the universe? 867 00:43:48,140 --> 00:43:52,590 - [Speaker 11] There's a whole series of coincidences, 868 00:43:52,590 --> 00:43:57,120 effectively, that seem to have conspired to allow our life 869 00:43:57,120 --> 00:43:59,240 to be here on this planet. 870 00:43:59,240 --> 00:44:01,300 If you mess around with the fundamental constant, 871 00:44:01,300 --> 00:44:03,020 you mess around with the fundamental masses, 872 00:44:03,020 --> 00:44:07,800 it's very easy to create a sterile universe. 873 00:44:07,800 --> 00:44:10,020 I mean, the example is-- is very similar to human 874 00:44:10,020 --> 00:44:11,300 being, right? 875 00:44:11,300 --> 00:44:13,700 You're made of a bunch of atoms, you've got carbon, 876 00:44:13,700 --> 00:44:14,880 you've got iron, you've got lots 877 00:44:14,880 --> 00:44:17,400 of oxygen, lots of hydrogen. 878 00:44:17,400 --> 00:44:20,280 There are many, many ways of arranging those atoms to create 879 00:44:20,280 --> 00:44:22,320 an amorphous dead blob. 880 00:44:22,320 --> 00:44:24,520 There's a very small number of ways to arrange them 881 00:44:24,520 --> 00:44:26,240 to create a living person. 882 00:44:26,240 --> 00:44:28,320 And it's a similar thing with the universe. 883 00:44:28,320 --> 00:44:30,120 If you mess around with the fundamental makeup 884 00:44:30,120 --> 00:44:32,460 of the universe, it's very easy to make a dead one. 885 00:44:32,460 --> 00:44:35,830 (OMINOUS MUSIC) 886 00:44:36,830 --> 00:44:39,180 - [Speaker 4] Is the universe somehow fine tuned? 887 00:44:39,180 --> 00:44:41,800 Is there something special about our universe? 888 00:44:41,800 --> 00:44:43,420 I think the answer to that is no. 889 00:44:43,420 --> 00:44:44,540 There doesn't seem to be one. 890 00:44:44,540 --> 00:44:46,360 I know some of my colleagues think that, oh, 891 00:44:46,360 --> 00:44:49,160 since our universe-- the constants of our universe 892 00:44:49,160 --> 00:44:51,940 seem to have been fine tuned to allow us to exist. 893 00:44:51,940 --> 00:44:52,940 But I don't buy that. 894 00:44:52,940 --> 00:44:55,340 I don't believe it's true because in order 895 00:44:55,340 --> 00:44:56,340 to have fine tuning-- 896 00:44:56,340 --> 00:44:58,440 You know, when you have a radio, you have a knob 897 00:44:58,440 --> 00:45:00,630 and you fine tune it by going like this. 898 00:45:00,630 --> 00:45:02,200 When you do that, you need to know that there's 899 00:45:02,200 --> 00:45:04,480 a range that you can sample. 900 00:45:04,480 --> 00:45:08,880 And the reality is we do not know the range of that knob. 901 00:45:08,880 --> 00:45:10,640 And if you don't know the range, 902 00:45:10,640 --> 00:45:14,620 you can't even assign a meaning to the word fine tuned. 903 00:45:14,620 --> 00:45:17,200 And that's why I think the whole argument falls apart. 904 00:45:17,200 --> 00:45:19,180 And so I don't see any designer there. 905 00:45:19,180 --> 00:45:23,080 I think there's-- things are some way, uh, whether they 906 00:45:23,080 --> 00:45:24,960 could have been otherwise is-- 907 00:45:24,960 --> 00:45:27,340 you know, that's a function of people's imagination. 908 00:45:33,770 --> 00:45:35,040 - [Speaker 13] The universe that 909 00:45:35,040 --> 00:45:37,440 we live in has allowed for human 910 00:45:37,440 --> 00:45:41,400 life to come into existence. 911 00:45:41,400 --> 00:45:43,940 Planet Earth, if it was too much closer to the sun, 912 00:45:43,940 --> 00:45:44,940 it would be too hot. 913 00:45:44,940 --> 00:45:47,200 If it was too further away, it would be too cold. 914 00:45:47,200 --> 00:45:50,180 If it was much more massive, then maybe DNA wouldn't grow. 915 00:45:50,180 --> 00:45:51,300 And if it wasn't massive enough, 916 00:45:51,300 --> 00:45:54,310 it wouldn't hold on to an atmosphere. 917 00:45:54,310 --> 00:45:55,410 We live around the sun. 918 00:45:55,410 --> 00:45:57,330 That's very boring and evolving very slowly, 919 00:45:57,330 --> 00:45:59,870 very quiescent, not too violent, 920 00:45:59,870 --> 00:46:01,730 which is great for life to occur over. 921 00:46:04,630 --> 00:46:06,730 We live in a part of the galaxy that's not too violent. 922 00:46:06,730 --> 00:46:09,400 We're way out in the-- in the outskirts, in the suburbs, 923 00:46:09,400 --> 00:46:10,470 rather than in the center, where 924 00:46:10,470 --> 00:46:11,910 there's a gigantic black hole spewing 925 00:46:11,910 --> 00:46:13,330 out stuff in all directions. 926 00:46:16,630 --> 00:46:18,630 So this idea is that this universe 927 00:46:18,630 --> 00:46:20,310 is just so-- just right to allow 928 00:46:20,310 --> 00:46:21,970 humans to come into existence. 929 00:46:21,970 --> 00:46:23,270 But there could be many other universes 930 00:46:23,270 --> 00:46:25,750 with different parameter sets where you would not 931 00:46:25,750 --> 00:46:27,650 have evolved some sort of intelligent life, 932 00:46:27,650 --> 00:46:29,270 certainly not human life. 933 00:46:29,270 --> 00:46:32,070 So people are attracted to the idea 934 00:46:32,070 --> 00:46:34,870 that our universe is a statistical fluke 935 00:46:34,870 --> 00:46:36,670 that allowed for human life. 936 00:46:36,670 --> 00:46:39,470 And there'll be infinite number of other universes 937 00:46:39,470 --> 00:46:41,630 with different sets of fundamental parameters 938 00:46:41,630 --> 00:46:44,670 of nature that evolve boring universes that collapse 939 00:46:44,670 --> 00:46:47,770 quickly, that evolve universes that get much, much bigger, 940 00:46:47,770 --> 00:46:50,110 accelerate much, much faster, and maybe other 941 00:46:50,110 --> 00:46:52,800 universes beyond that that have seven, eight, 15 or 942 00:46:52,800 --> 00:46:53,960 105 dimensions. 943 00:46:53,960 --> 00:46:54,960 We just don't know. 944 00:47:00,760 --> 00:47:05,300 - [Spekaer 12] Why is our universe hospitable to life? 945 00:47:05,300 --> 00:47:09,500 It would be easy to imagine that if we had a slightly 946 00:47:09,500 --> 00:47:11,060 different speed of light or charge 947 00:47:11,060 --> 00:47:13,700 on the electron or something, then stars couldn't form 948 00:47:13,700 --> 00:47:15,960 and complex chemistry couldn't exist. 949 00:47:15,960 --> 00:47:17,670 It's actually quite finely balanced. 950 00:47:17,670 --> 00:47:19,620 (GENTLE MUSIC) 951 00:47:19,620 --> 00:47:24,300 So to explain that multiverses actually come in handy 952 00:47:24,300 --> 00:47:27,460 because if there's lots of different universes with lots 953 00:47:27,460 --> 00:47:30,000 of different possible constants of nature, 954 00:47:30,000 --> 00:47:32,100 then we would just happen to find ourselves 955 00:47:32,100 --> 00:47:35,100 in the one in which life was possible, because obviously 956 00:47:35,100 --> 00:47:37,220 we're not going to find ourselves in one 957 00:47:37,220 --> 00:47:41,220 in which life was impossible. 958 00:47:41,220 --> 00:47:43,900 So if there's many, many universes, 959 00:47:43,900 --> 00:47:46,700 that would explain, naturally why 960 00:47:46,700 --> 00:47:48,820 we happen to find ourselves in the universe 961 00:47:48,820 --> 00:47:50,140 that's hospitable to life. 962 00:47:53,010 --> 00:47:54,970 - [Narrator] So multiverses could 963 00:47:54,970 --> 00:47:59,690 explain a lot of unanswered questions about our universe. 964 00:47:59,690 --> 00:48:03,050 Whether multiverses exist is still unknown. 965 00:48:03,050 --> 00:48:05,450 But more and more physicists are starting 966 00:48:05,450 --> 00:48:08,810 to embrace the theory. 967 00:48:08,810 --> 00:48:13,690 Maybe one day we will find proof that they exist, 968 00:48:13,690 --> 00:48:18,550 and we will have our minds and reality expanded once again. 969 00:48:22,450 --> 00:48:25,800 (THEME MUSIC)