1 00:00:08,360 --> 00:00:11,200 Speaker 1: Hey, Jorge, are you a hoarder or do you like 2 00:00:11,280 --> 00:00:15,680 Speaker 1: to throw things away? We keep everything, we have, every drawing, 3 00:00:15,680 --> 00:00:20,320 Speaker 1: my kids ever made. Man, not me. I value space 4 00:00:20,560 --> 00:00:24,400 Speaker 1: more than stuff. I love to throw things away. Wow, 5 00:00:24,440 --> 00:00:26,320 Speaker 1: what does your family give you for your birthday? Then? 6 00:00:26,600 --> 00:00:30,200 Speaker 1: Empty space? Actually, my wife rent a dumpster and says 7 00:00:30,240 --> 00:00:33,320 Speaker 1: I can throw out anything I want. It's like a 8 00:00:33,360 --> 00:00:36,600 Speaker 1: negative present. Hey, space is precious. You know you can't 9 00:00:36,640 --> 00:00:38,680 Speaker 1: have too much of it. You can't have too much 10 00:00:38,760 --> 00:00:42,519 Speaker 1: nothing said nobody never, Nothing is better than nothing. This 11 00:00:42,640 --> 00:01:00,600 Speaker 1: is the best nothing I ever got. Hi more handmade 12 00:01:00,600 --> 00:01:04,000 Speaker 1: cartoonists and the creator of PhD comics. Hi. I'm Daniel, 13 00:01:04,080 --> 00:01:07,399 Speaker 1: I'm a particle physicist and I really do love space. 14 00:01:07,720 --> 00:01:10,080 Speaker 1: And Welcome to our podcast. Daniel and Jorge explain the 15 00:01:10,160 --> 00:01:13,160 Speaker 1: university production of I Heart Radio, in which we explore 16 00:01:13,319 --> 00:01:17,240 Speaker 1: all the stuff in space, empty space, not so empty space, 17 00:01:17,319 --> 00:01:20,840 Speaker 1: space builled with really crazy bonk, or stuff that's hard 18 00:01:20,880 --> 00:01:24,960 Speaker 1: to understand, and sometimes even the very nature of space. 19 00:01:25,120 --> 00:01:27,200 Speaker 1: We talk about all of these things in this podcast, 20 00:01:27,280 --> 00:01:29,080 Speaker 1: and we break them down, and our goal is to 21 00:01:29,200 --> 00:01:31,960 Speaker 1: deliver them to you in a way that actually makes sense, 22 00:01:31,959 --> 00:01:34,840 Speaker 1: so you go away thinking, huh, I get it, or 23 00:01:34,880 --> 00:01:37,760 Speaker 1: at least I get it as much as scientists get it, 24 00:01:37,800 --> 00:01:40,720 Speaker 1: which sometimes isn't that much. And sometimes it feels like 25 00:01:40,760 --> 00:01:43,760 Speaker 1: we're talking about a whole lot of nothing, and sometimes 26 00:01:43,800 --> 00:01:46,400 Speaker 1: we are literally talking about nothing, and sometimes we're trying 27 00:01:46,400 --> 00:01:51,360 Speaker 1: to figure out what is nothing exactly right. Yeah, deep questions, now, Daniel, 28 00:01:51,400 --> 00:01:53,040 Speaker 1: when you say you love space, do you mean like 29 00:01:53,120 --> 00:01:56,720 Speaker 1: you love, you know, just space travel, like where the 30 00:01:56,760 --> 00:01:59,240 Speaker 1: planets are, or did you just like, you know, having 31 00:01:59,520 --> 00:02:02,120 Speaker 1: the idea of space in your life. I love all 32 00:02:02,160 --> 00:02:04,639 Speaker 1: of it. I love outer space, I love deep space. 33 00:02:04,680 --> 00:02:07,160 Speaker 1: I live near space. I also love having space in 34 00:02:07,160 --> 00:02:09,480 Speaker 1: my living room, Like it's not unusual for me to 35 00:02:09,480 --> 00:02:11,240 Speaker 1: toss out a piece of furniture and go, you know what, 36 00:02:11,560 --> 00:02:14,240 Speaker 1: the room is just better with nothing there. You like 37 00:02:14,280 --> 00:02:16,840 Speaker 1: everything about space. There's nothing negative about space for you. 38 00:02:17,800 --> 00:02:20,040 Speaker 1: I'm pretty pro space. Yeah. Absolutely, you would live in 39 00:02:20,080 --> 00:02:23,480 Speaker 1: an empty box if you could, exactly. I'm like a 40 00:02:23,520 --> 00:02:26,840 Speaker 1: cat that way. Are you looking forward and to your 41 00:02:26,919 --> 00:02:29,519 Speaker 1: children leaving the house then, because that's just more space, 42 00:02:30,400 --> 00:02:32,680 Speaker 1: is more space. I'm not looking for to them leaving, 43 00:02:32,840 --> 00:02:34,560 Speaker 1: but if they do, I'm looking forward to throwing all 44 00:02:34,560 --> 00:02:37,520 Speaker 1: their stuff away. Oh man, that's going to come back 45 00:02:37,560 --> 00:02:40,720 Speaker 1: to want you. They're like, why did you throw away 46 00:02:40,760 --> 00:02:45,119 Speaker 1: my comic book collection that's worth three million dollars? Now, yeah, exactly, 47 00:02:45,160 --> 00:02:48,079 Speaker 1: but this space is priceless, right, Well, we like to 48 00:02:48,120 --> 00:02:51,520 Speaker 1: talk about space in this podcast and also about what 49 00:02:51,639 --> 00:02:53,880 Speaker 1: it represents, what it means, because it's kind of a 50 00:02:54,000 --> 00:02:57,760 Speaker 1: topic that businesses don't have a super clear idea about. 51 00:02:57,880 --> 00:03:00,320 Speaker 1: That's right. It's one of these really fun quite in 52 00:03:00,360 --> 00:03:03,240 Speaker 1: physics because only recently did we figure out that it's 53 00:03:03,280 --> 00:03:05,720 Speaker 1: a question that sort of has an answer. It's a 54 00:03:05,800 --> 00:03:08,720 Speaker 1: question that's worth asking. It's one of these questions that's 55 00:03:08,760 --> 00:03:11,000 Speaker 1: so basic that we just sort of assumed we knew 56 00:03:11,040 --> 00:03:13,520 Speaker 1: the answer. You know, space is space. It's the nothing, 57 00:03:13,560 --> 00:03:16,840 Speaker 1: it's the emptiness. And only recently have we realized, Wow, 58 00:03:16,880 --> 00:03:19,639 Speaker 1: space could be much more than that, and it really 59 00:03:19,680 --> 00:03:23,160 Speaker 1: deserves our attention. Right. Even more important is this sort 60 00:03:23,160 --> 00:03:27,080 Speaker 1: of idea that maybe we don't need space, Like maybe 61 00:03:27,160 --> 00:03:30,080 Speaker 1: it's just sort of like an add on to the universe. Yeah, 62 00:03:30,200 --> 00:03:32,640 Speaker 1: is it at the foundation of reality or is it 63 00:03:32,720 --> 00:03:35,800 Speaker 1: just something that fills up something else? You know, imagine 64 00:03:35,840 --> 00:03:37,560 Speaker 1: what it would have been like to be a person 65 00:03:37,640 --> 00:03:40,600 Speaker 1: ten thousand years ago. You never would have experienced reality 66 00:03:40,640 --> 00:03:43,880 Speaker 1: without air, for example, So the concept of like a vacuum, 67 00:03:43,880 --> 00:03:46,040 Speaker 1: a place where there was no air would have been 68 00:03:46,080 --> 00:03:48,640 Speaker 1: totally alien to you. So now, of course we know 69 00:03:48,720 --> 00:03:50,920 Speaker 1: that that's possible. It seems obvious that air is not 70 00:03:51,040 --> 00:03:53,560 Speaker 1: a fundamental property of the universe. But we're at the 71 00:03:53,600 --> 00:03:56,640 Speaker 1: next level and wondering, like, well, is space fundamental? Could 72 00:03:56,640 --> 00:03:59,240 Speaker 1: you take it apart? Do you really need it? Yeah? 73 00:03:59,480 --> 00:04:02,280 Speaker 1: In fact, so the universe, it doesn't have any air 74 00:04:02,360 --> 00:04:06,120 Speaker 1: in it, right, most of the universe is pretty empty. Yeah, 75 00:04:06,240 --> 00:04:08,320 Speaker 1: from that point of view, exactly, we were dealing with 76 00:04:08,360 --> 00:04:11,720 Speaker 1: a very unrepresentative example. And we do this all the 77 00:04:11,800 --> 00:04:15,000 Speaker 1: time in science. We assume that the things we experience 78 00:04:15,080 --> 00:04:18,400 Speaker 1: our universal and we can generalize from these examples to 79 00:04:18,480 --> 00:04:21,039 Speaker 1: the whole universe. We're doing this all the time, left 80 00:04:21,080 --> 00:04:23,760 Speaker 1: and right without even realizing it. So now we're asking 81 00:04:23,760 --> 00:04:27,200 Speaker 1: a similar question about space. You know, our our assumptions 82 00:04:27,200 --> 00:04:30,160 Speaker 1: about space valid. Can we break it apart? Do we 83 00:04:30,240 --> 00:04:32,120 Speaker 1: even need it? Is it possible for it to have 84 00:04:32,200 --> 00:04:35,640 Speaker 1: bubbled up from something else? Yeah, it's a space topic. 85 00:04:35,839 --> 00:04:37,800 Speaker 1: But space is pretty empty. I think we have a 86 00:04:37,800 --> 00:04:40,599 Speaker 1: whole podcast episode about that, right, Like, what's the average 87 00:04:40,640 --> 00:04:43,040 Speaker 1: density of the universe or like how much stuff is 88 00:04:43,080 --> 00:04:46,560 Speaker 1: there really on a like cubic foot Yeah, we do 89 00:04:46,640 --> 00:04:48,960 Speaker 1: have a whole podcast about how empty spaces and we 90 00:04:49,000 --> 00:04:50,640 Speaker 1: take you on a journey from the top of the 91 00:04:50,680 --> 00:04:54,520 Speaker 1: atmosphere into the Solar System and then out into interstellar 92 00:04:54,560 --> 00:04:58,520 Speaker 1: space and then finally into intergalactic space. And mostly space 93 00:04:58,680 --> 00:05:02,640 Speaker 1: is intergalactic space, right, Like there are these huge streams 94 00:05:02,680 --> 00:05:06,520 Speaker 1: of galactic clusters of galaxies swinging around each other, but 95 00:05:06,640 --> 00:05:09,480 Speaker 1: between them there are these vast bubbles and voids that 96 00:05:09,720 --> 00:05:12,720 Speaker 1: don't have galaxies in them. So most of the universe 97 00:05:12,760 --> 00:05:17,120 Speaker 1: sort of by volume, is this intergalactic space, which is 98 00:05:17,120 --> 00:05:19,120 Speaker 1: not totally empty. There's still stuff in there. That's a 99 00:05:19,160 --> 00:05:22,120 Speaker 1: little bit of dark matter, there's definitely dark energy. But 100 00:05:22,400 --> 00:05:24,839 Speaker 1: it's most of the universe and it's pretty empty, but 101 00:05:25,040 --> 00:05:28,280 Speaker 1: not down to zero. Yeah, and there's a lot of 102 00:05:28,320 --> 00:05:31,400 Speaker 1: it space, I mean, in the universe, there's a whole 103 00:05:31,400 --> 00:05:32,800 Speaker 1: bunch of it. Like if you are going at the 104 00:05:32,800 --> 00:05:35,240 Speaker 1: speed of light, it would still take you as far 105 00:05:35,279 --> 00:05:37,799 Speaker 1: as we know right now, you know, tens of billions 106 00:05:37,880 --> 00:05:40,040 Speaker 1: of years just to go from one side to the other. 107 00:05:40,480 --> 00:05:42,760 Speaker 1: That's a lot of time. Absolutely, And remember the speed 108 00:05:42,760 --> 00:05:45,080 Speaker 1: of light is like mind boggling lee fast, right, It's 109 00:05:45,120 --> 00:05:49,440 Speaker 1: incredibly fast. And yet these distances, even inside our Solar 110 00:05:49,480 --> 00:05:53,080 Speaker 1: System are incredible, Like it takes minutes for light to 111 00:05:53,120 --> 00:05:55,880 Speaker 1: get from here just to Mars, which is our neighbor, 112 00:05:56,360 --> 00:05:58,839 Speaker 1: and hours to get out to the outer Solar system. 113 00:05:59,000 --> 00:06:01,960 Speaker 1: You know, when we communicate with probes and rovers and 114 00:06:02,000 --> 00:06:04,600 Speaker 1: stuff on other planets, the reason you can't drive them 115 00:06:04,680 --> 00:06:07,400 Speaker 1: is because they are so far away. You can't do 116 00:06:07,480 --> 00:06:09,880 Speaker 1: real time driving because the lag is too long. And 117 00:06:09,880 --> 00:06:13,200 Speaker 1: that's just inside our Solar system. So the distances to 118 00:06:13,320 --> 00:06:16,880 Speaker 1: other galaxies millions of light years and deeper into space 119 00:06:16,960 --> 00:06:19,040 Speaker 1: billions of light years, they're hard for us to get 120 00:06:19,080 --> 00:06:22,200 Speaker 1: our mind around. So, yeah, space is pretty spacious. I 121 00:06:22,200 --> 00:06:23,960 Speaker 1: guess I hadn't thought about it before. Like if even 122 00:06:24,000 --> 00:06:26,720 Speaker 1: if you're Superman or Superwoman and you're traveling, you can 123 00:06:26,800 --> 00:06:28,200 Speaker 1: you're able to fly at the speed of light, it 124 00:06:28,200 --> 00:06:31,039 Speaker 1: would still take you like a billion years just to 125 00:06:31,320 --> 00:06:33,880 Speaker 1: you know, go to the other galaxies out there in 126 00:06:33,880 --> 00:06:36,560 Speaker 1: the universe. Yeah, well that's an interesting question. Does Superman 127 00:06:36,640 --> 00:06:38,440 Speaker 1: have to travel at the speed of light? Can he 128 00:06:38,520 --> 00:06:41,880 Speaker 1: be superluminal? I mean, how far away is his home 129 00:06:41,920 --> 00:06:44,640 Speaker 1: planet anyway, I don't know you're the physicist. I just 130 00:06:44,640 --> 00:06:47,760 Speaker 1: read the comic books. I don't dissect them scientifically. I'll 131 00:06:47,800 --> 00:06:49,880 Speaker 1: go find out exactly where his home planet is and 132 00:06:49,920 --> 00:06:52,360 Speaker 1: figure out if he broke the law on the way here, 133 00:06:52,360 --> 00:06:54,560 Speaker 1: and if so, I'll issue him a physics ticket. Well, 134 00:06:54,560 --> 00:06:56,600 Speaker 1: he can just bring it up with his heat visioned Daniel. 135 00:06:57,040 --> 00:06:58,600 Speaker 1: And also, how are you going to arrest him? Good 136 00:06:58,680 --> 00:07:04,719 Speaker 1: luck with that, citizens arrest Mr Superman. But yeah, there's 137 00:07:04,760 --> 00:07:06,719 Speaker 1: a lot of space out there. It's definitely not a 138 00:07:06,760 --> 00:07:09,360 Speaker 1: small part of the universe. But I guess the question 139 00:07:09,520 --> 00:07:13,280 Speaker 1: is it a necessary part of the universe. So today 140 00:07:13,280 --> 00:07:20,960 Speaker 1: on the podcast, we'll be asking the question can the 141 00:07:21,080 --> 00:07:27,520 Speaker 1: universe exist without space? Space? Space? Space space? That question 142 00:07:27,600 --> 00:07:29,840 Speaker 1: is so profound it needs an echo. It echoes through 143 00:07:29,840 --> 00:07:33,480 Speaker 1: the vacuum of infinity, through the vacuum of our understanding 144 00:07:33,600 --> 00:07:36,800 Speaker 1: of the universe. Absolutely, through the empty space in my head. 145 00:07:37,560 --> 00:07:39,800 Speaker 1: But it's a fun question, and it sort of mirrors 146 00:07:39,840 --> 00:07:42,120 Speaker 1: the way I treat furniture. You know, I look around 147 00:07:42,160 --> 00:07:44,440 Speaker 1: my house and I asked myself, do we need that chair? 148 00:07:44,520 --> 00:07:46,760 Speaker 1: Nobody ever sits there and we get rid of it. 149 00:07:46,800 --> 00:07:49,880 Speaker 1: We're like, ah, it's better off. And now we're cycling 150 00:07:49,880 --> 00:07:52,400 Speaker 1: through modern physics and we're like, m, do we really 151 00:07:52,440 --> 00:07:55,560 Speaker 1: need the whole concept of space? Like is it really 152 00:07:55,920 --> 00:07:58,400 Speaker 1: have to be included in the sort of fundamental list 153 00:07:58,440 --> 00:08:00,960 Speaker 1: of things you need to build a universe or is 154 00:08:00,960 --> 00:08:03,840 Speaker 1: it like you know, ice cubes or atoms or hurricanes, 155 00:08:04,200 --> 00:08:07,560 Speaker 1: something that you know comes from your more basic ingredients. 156 00:08:07,680 --> 00:08:09,320 Speaker 1: I would hate to be a furniture in your house. 157 00:08:09,360 --> 00:08:12,400 Speaker 1: I feel like I would live in constant fear. Yes, absolutely, 158 00:08:12,520 --> 00:08:15,840 Speaker 1: you must constantly justify your existence in my house, or 159 00:08:16,000 --> 00:08:19,640 Speaker 1: you're on the trashy. It's like huff Post reporters. You know, 160 00:08:19,920 --> 00:08:23,160 Speaker 1: hopefully that's just for your furniture, not your family as well. 161 00:08:23,320 --> 00:08:26,960 Speaker 1: Or pets. Absolutely, living creatures definitely belong to the family. 162 00:08:27,040 --> 00:08:29,360 Speaker 1: Chairs not so much so if you could have a 163 00:08:29,360 --> 00:08:31,920 Speaker 1: bigger house, would you have a bigger house? No? No, 164 00:08:32,000 --> 00:08:33,960 Speaker 1: I don't need a bigger house. In fact, I had 165 00:08:34,040 --> 00:08:36,120 Speaker 1: some friends who once moved to a bigger house and 166 00:08:36,120 --> 00:08:38,360 Speaker 1: I almost ruin their marriage because they ended up shouting 167 00:08:38,400 --> 00:08:41,439 Speaker 1: each other from different rooms across the house. And they 168 00:08:41,480 --> 00:08:43,040 Speaker 1: did better when they had to, you know, share a 169 00:08:43,040 --> 00:08:45,640 Speaker 1: small apartment. Yeah, we talked about this and I offered 170 00:08:45,640 --> 00:08:49,760 Speaker 1: the better solution of just getting an intercom system. You 171 00:08:49,800 --> 00:08:52,079 Speaker 1: are going to engineer everybody's marriage. Huh. I'm gonna go 172 00:08:52,120 --> 00:08:54,840 Speaker 1: to your your couple's counseling. There's a solution for everything 173 00:08:54,840 --> 00:08:58,280 Speaker 1: in engineering, marital engineering. Wow, that's a better name for therapist. 174 00:08:58,760 --> 00:09:00,840 Speaker 1: But anyways, Yeah, it's a big question whether or not 175 00:09:00,960 --> 00:09:04,240 Speaker 1: we need space in the universe. It seems pretty fundamental, 176 00:09:04,480 --> 00:09:07,280 Speaker 1: you know, like, how can you have a universe without space? Like, 177 00:09:07,400 --> 00:09:10,440 Speaker 1: isn't space the universe? Yeah, but just because it's hard 178 00:09:10,440 --> 00:09:13,640 Speaker 1: to imagine doesn't mean it's not reality. Right. A lot 179 00:09:13,720 --> 00:09:16,320 Speaker 1: of what reality is was difficult for us to wrap 180 00:09:16,360 --> 00:09:19,040 Speaker 1: our minds around. So when you do this kind of exploration, 181 00:09:19,040 --> 00:09:21,480 Speaker 1: you got to sort of be willing to give up 182 00:09:21,559 --> 00:09:25,400 Speaker 1: something you thought was fundamental, something you assumed was inherent, 183 00:09:25,480 --> 00:09:28,760 Speaker 1: and ask your question whether it can come from something else. 184 00:09:28,880 --> 00:09:31,080 Speaker 1: All right, Well, as usual, we were wondering how many 185 00:09:31,080 --> 00:09:34,440 Speaker 1: people out there have thought about this spacious question, whether 186 00:09:34,559 --> 00:09:37,760 Speaker 1: or not we need space. So Daniel went out there 187 00:09:37,840 --> 00:09:40,480 Speaker 1: into the well to the internet to ask people is 188 00:09:40,520 --> 00:09:43,679 Speaker 1: it possible to have a universe without space. Here's what 189 00:09:43,720 --> 00:09:47,240 Speaker 1: they had to say. Oh, that's a good question. I 190 00:09:47,280 --> 00:09:52,120 Speaker 1: don't think, so okay, why, Well, I don't know. I 191 00:09:52,280 --> 00:09:54,520 Speaker 1: don't know. I don't know. I don't know why. I 192 00:09:54,640 --> 00:09:59,400 Speaker 1: just know I think space is only one of the dimensions, right, 193 00:10:00,160 --> 00:10:01,920 Speaker 1: you can probably have a universe. It's just time and 194 00:10:01,960 --> 00:10:06,760 Speaker 1: maybe not space. I'm gonna say yes. Well, my understanding 195 00:10:06,840 --> 00:10:11,360 Speaker 1: is that, yeah, I guess you can. Um. I mean, 196 00:10:11,520 --> 00:10:14,600 Speaker 1: was this space when the Big Bang occurred in the 197 00:10:14,640 --> 00:10:17,560 Speaker 1: moments after that, or was it all dense metal with 198 00:10:17,679 --> 00:10:22,080 Speaker 1: zero space? But my understanding is that if you have 199 00:10:22,120 --> 00:10:24,680 Speaker 1: a different universe that could operate off a completely different 200 00:10:24,679 --> 00:10:27,800 Speaker 1: set of physical laws. So I guess never say never 201 00:10:27,880 --> 00:10:32,480 Speaker 1: in that regard. You can have a universe without space. 202 00:10:34,120 --> 00:10:41,720 Speaker 1: Our situation with matter having out competed antimatter, I think 203 00:10:41,920 --> 00:10:48,960 Speaker 1: is actually pretty unique. Um there, and I would I 204 00:10:49,000 --> 00:10:52,840 Speaker 1: think they're a little universe blips all over where universe 205 00:10:52,920 --> 00:10:58,320 Speaker 1: pops into existence and annihilates and no spaces created. I 206 00:10:58,320 --> 00:11:02,880 Speaker 1: guess you can have universe with out just this dimension space, 207 00:11:04,160 --> 00:11:08,640 Speaker 1: and you can have all the other dimensions possible, but 208 00:11:09,600 --> 00:11:12,720 Speaker 1: it will be crowded. I guess it would mean what 209 00:11:12,800 --> 00:11:16,920 Speaker 1: you mean by universe, because before the Big Bang all 210 00:11:17,000 --> 00:11:20,200 Speaker 1: the universe was there. It was just compressed and to 211 00:11:20,320 --> 00:11:23,520 Speaker 1: my knowledge, there was no space. So if you can't 212 00:11:23,559 --> 00:11:26,959 Speaker 1: that just the universe then yeah, all right, some mixed 213 00:11:27,000 --> 00:11:29,559 Speaker 1: reactions here. Some people could live without it, some people 214 00:11:29,640 --> 00:11:32,079 Speaker 1: could really want it. Yeah. It basically wraps up the 215 00:11:32,120 --> 00:11:35,280 Speaker 1: whole question of what spaces and where it comes from 216 00:11:35,280 --> 00:11:38,160 Speaker 1: and all these answers I see echoes of general relativity 217 00:11:38,160 --> 00:11:41,880 Speaker 1: and quantum mechanical perspectives on this question. So good job listeners, 218 00:11:42,160 --> 00:11:44,199 Speaker 1: And to those of you who would like to participate 219 00:11:44,240 --> 00:11:48,200 Speaker 1: in future rounds of answer random questions for the podcast, 220 00:11:48,280 --> 00:11:51,079 Speaker 1: please write to us two questions at Daniel and Jorge 221 00:11:51,120 --> 00:11:53,000 Speaker 1: dot com. There's a lot of reference here and the 222 00:11:53,000 --> 00:11:55,640 Speaker 1: answers to the Big Bang to write that's something I 223 00:11:55,640 --> 00:11:58,560 Speaker 1: hadn't thought about before. Was their space before the Big Bang? 224 00:11:58,640 --> 00:12:01,600 Speaker 1: At the Big Bang? Or was space created at some 225 00:12:01,720 --> 00:12:05,760 Speaker 1: point in the history of the universe? Yeah, space and time? Right, 226 00:12:06,000 --> 00:12:08,840 Speaker 1: all right, Well, let's dig into it, Daniel. Let's start 227 00:12:08,840 --> 00:12:11,280 Speaker 1: with maybe the basic stuff, like what is space? How 228 00:12:11,320 --> 00:12:15,000 Speaker 1: do physicists think about what space is? Yeah, this is 229 00:12:15,000 --> 00:12:18,440 Speaker 1: a great question, and we have sort of two answers 230 00:12:18,520 --> 00:12:22,040 Speaker 1: for what space is based on whether you're thinking about 231 00:12:22,040 --> 00:12:24,400 Speaker 1: it from the point of view of like quantum mechanics 232 00:12:24,760 --> 00:12:26,400 Speaker 1: or whether you're thinking about it from the point of 233 00:12:26,440 --> 00:12:29,480 Speaker 1: view of general relativity. And remember that these are the 234 00:12:29,520 --> 00:12:33,320 Speaker 1: two pillars of thinking in modern physics, too great ways 235 00:12:33,360 --> 00:12:37,160 Speaker 1: to describe parts of the experiments we've done. Quantum Mechanics 236 00:12:37,240 --> 00:12:40,280 Speaker 1: describes basically everything that has to do with little particles 237 00:12:40,280 --> 00:12:43,280 Speaker 1: at small scales and all the forces that were familiar 238 00:12:43,320 --> 00:12:46,640 Speaker 1: with except for gravity, and general relativity talks about how 239 00:12:46,720 --> 00:12:49,320 Speaker 1: space is curved and it's bent, and that's really what 240 00:12:49,520 --> 00:12:52,200 Speaker 1: gravity is. And so the answer to the question what 241 00:12:52,440 --> 00:12:55,440 Speaker 1: is space sort of depends on whose perspective you want 242 00:12:55,480 --> 00:12:57,360 Speaker 1: to take first? What do you mean, how can something 243 00:12:57,440 --> 00:13:00,400 Speaker 1: depend on your perspective? Aren't you looking for like one answer? 244 00:13:00,559 --> 00:13:03,400 Speaker 1: We are absolutely looking for one answer, but we don't 245 00:13:03,480 --> 00:13:06,640 Speaker 1: have one answer. We have two theories, quantum mechanics and 246 00:13:06,679 --> 00:13:10,480 Speaker 1: general relativity. They treat space very differently and we haven't 247 00:13:10,480 --> 00:13:12,880 Speaker 1: been able to unify them. So the short answer is 248 00:13:13,000 --> 00:13:15,000 Speaker 1: we don't know what space is because we don't have 249 00:13:15,040 --> 00:13:18,400 Speaker 1: a single coherent theory for the whole universe, and the 250 00:13:18,440 --> 00:13:21,760 Speaker 1: two theories we do have disagree about what space is, 251 00:13:21,800 --> 00:13:23,959 Speaker 1: all right, So what are the two theories about space? 252 00:13:24,240 --> 00:13:27,160 Speaker 1: And is there enough space between them to tell the difference. Well, 253 00:13:27,200 --> 00:13:30,920 Speaker 1: you know, let's start with quantum mechanics. Quantum mechanics is 254 00:13:30,960 --> 00:13:34,240 Speaker 1: the theory that tells us how electromagnetism works, how the 255 00:13:34,280 --> 00:13:37,440 Speaker 1: weak force works, you know, how photons move, and it 256 00:13:37,520 --> 00:13:41,840 Speaker 1: tells us that space is fundamental. It assumes that space 257 00:13:41,880 --> 00:13:44,320 Speaker 1: exists and it adds stuff to it. So if you're 258 00:13:44,320 --> 00:13:47,280 Speaker 1: gonna build a universe using at least our current theory 259 00:13:47,320 --> 00:13:49,960 Speaker 1: of quantum mechanics, then you start from space. You say, 260 00:13:50,080 --> 00:13:52,600 Speaker 1: let's assume there's a space, and then at every point 261 00:13:52,640 --> 00:13:54,560 Speaker 1: in that space, I'm gonna say whether or not there's 262 00:13:54,559 --> 00:13:56,840 Speaker 1: a quantum field and how much energy it has. But 263 00:13:56,960 --> 00:13:59,160 Speaker 1: it's sort of like at the bedrock of the whole theory, 264 00:13:59,240 --> 00:14:03,040 Speaker 1: just like assuming that space and time are things that 265 00:14:03,120 --> 00:14:05,480 Speaker 1: you can put fields in them, right, because that's kind 266 00:14:05,520 --> 00:14:08,680 Speaker 1: of baked into the definition of a field, right, Like 267 00:14:08,760 --> 00:14:11,280 Speaker 1: you can't have a field without space, like a field 268 00:14:11,440 --> 00:14:15,240 Speaker 1: is by definition like how things vary in a space. 269 00:14:15,360 --> 00:14:17,920 Speaker 1: That's right exactly. And we'll talk later about whether you 270 00:14:17,920 --> 00:14:21,600 Speaker 1: can generalize that to like abstract spaces rather than physical 271 00:14:21,680 --> 00:14:24,160 Speaker 1: spaces and what that means. But you're right for the 272 00:14:24,160 --> 00:14:26,600 Speaker 1: physical fields that we're talking about, you know, like the 273 00:14:26,600 --> 00:14:30,560 Speaker 1: photon field. It's just a value all through space. But 274 00:14:30,640 --> 00:14:32,800 Speaker 1: as you say, space is fundamental to that. You need 275 00:14:32,880 --> 00:14:35,320 Speaker 1: to know like there's a certain value of field here 276 00:14:35,440 --> 00:14:39,160 Speaker 1: and over there at a different location in space, it 277 00:14:39,240 --> 00:14:41,560 Speaker 1: has a different value. And for example, the shrouding your 278 00:14:41,600 --> 00:14:46,080 Speaker 1: equation tells us how a wave function exists across space, 279 00:14:46,120 --> 00:14:49,120 Speaker 1: and how that wave function evolves through time it spreads 280 00:14:49,120 --> 00:14:52,880 Speaker 1: out through space, for example. So it's pretty deeply baked in. 281 00:14:53,120 --> 00:14:55,680 Speaker 1: So quantum field theory sort of the modern version of it, 282 00:14:55,720 --> 00:14:57,960 Speaker 1: as we think about it, doesn't really have an answer 283 00:14:58,000 --> 00:15:00,800 Speaker 1: to the question of what is space. It just sort 284 00:15:00,800 --> 00:15:03,840 Speaker 1: of like assumes it exists and starts from there. It's 285 00:15:03,880 --> 00:15:06,640 Speaker 1: like the basical list of ingredients. Would you say then 286 00:15:06,640 --> 00:15:10,600 Speaker 1: that maybe quantum fields defined space or do you think 287 00:15:10,840 --> 00:15:14,000 Speaker 1: space could exist without quantum fields. Well, that's a great question. 288 00:15:14,200 --> 00:15:17,880 Speaker 1: In our current theory, you can't have space without quantum fields, 289 00:15:17,880 --> 00:15:21,240 Speaker 1: Like quantum fields filled the entire universe. There's no sense 290 00:15:21,280 --> 00:15:23,280 Speaker 1: in which you could have space without them. That's just 291 00:15:23,280 --> 00:15:26,520 Speaker 1: sort of according to the theory. But do they define space? 292 00:15:27,040 --> 00:15:30,200 Speaker 1: I think they're deeply coupled to it. Yeah, absolutely, so 293 00:15:30,200 --> 00:15:32,680 Speaker 1: I think it's definitely part of the inherent nature of 294 00:15:32,720 --> 00:15:36,080 Speaker 1: space in quantum field theory that you have these fields 295 00:15:36,120 --> 00:15:38,480 Speaker 1: that live on top of it. But remember that quantum 296 00:15:38,520 --> 00:15:41,400 Speaker 1: field theory can also have stuff in it that doesn't 297 00:15:41,400 --> 00:15:43,920 Speaker 1: sort of come into the very beginning, right, Like we 298 00:15:43,960 --> 00:15:47,400 Speaker 1: can talk about the very basic ingredients of the universe, 299 00:15:47,680 --> 00:15:50,840 Speaker 1: space and quantum fields, but we don't add to that 300 00:15:50,920 --> 00:15:53,840 Speaker 1: things like you know the atom, right, The atom is 301 00:15:53,880 --> 00:15:56,760 Speaker 1: not a required element of the definition of the universe. 302 00:15:56,960 --> 00:16:00,040 Speaker 1: It comes from that other stuff. So the ad and 303 00:16:00,200 --> 00:16:02,920 Speaker 1: we think it exists, but it's not like fundamental. And 304 00:16:03,000 --> 00:16:04,920 Speaker 1: remember the goal of physics, as you say, is to 305 00:16:05,000 --> 00:16:09,040 Speaker 1: come to one theory, one explanation, one most basic list 306 00:16:09,120 --> 00:16:11,760 Speaker 1: of ingredients and the rules for combining them that then 307 00:16:11,840 --> 00:16:16,040 Speaker 1: explains everything else. So we're constantly trying to throw stuff 308 00:16:16,120 --> 00:16:18,680 Speaker 1: out on purpose so we can get like the minimal 309 00:16:18,760 --> 00:16:22,160 Speaker 1: list of fundamental things that can then explain everything else. 310 00:16:22,600 --> 00:16:25,320 Speaker 1: As emergent. We want to explain ice cream and atoms 311 00:16:25,320 --> 00:16:28,800 Speaker 1: and hurricanes in terms of the simpler, more basic elements. 312 00:16:28,880 --> 00:16:30,840 Speaker 1: Do you guys want the dumpster then too, so you 313 00:16:30,880 --> 00:16:34,640 Speaker 1: can throw out theories. I definitely want to throw space 314 00:16:34,680 --> 00:16:37,800 Speaker 1: out on the physics dumpster. I would love to explain 315 00:16:37,880 --> 00:16:40,920 Speaker 1: space in terms of something more basic and fundamental and say, man, 316 00:16:40,960 --> 00:16:43,760 Speaker 1: remember when we had space criming in here and we 317 00:16:43,800 --> 00:16:46,920 Speaker 1: had no space because we had so much space. But 318 00:16:46,960 --> 00:16:49,080 Speaker 1: then if there's no space, then there's no space in 319 00:16:49,080 --> 00:16:53,640 Speaker 1: the dumpster either, Daniel, where would you throw it out? Oh? Man, 320 00:16:53,760 --> 00:16:55,880 Speaker 1: I'll get a bigger dumpster, all right, So then that's 321 00:16:56,080 --> 00:16:59,960 Speaker 1: quantum mechanics. But then general relativity has a different view 322 00:17:00,160 --> 00:17:03,640 Speaker 1: of space. Yeah, General relativity tells us that space is 323 00:17:03,640 --> 00:17:06,560 Speaker 1: not something which is just like inherent and that you 324 00:17:06,600 --> 00:17:11,000 Speaker 1: can assume. General relativity tells us that space is really different. 325 00:17:11,200 --> 00:17:14,960 Speaker 1: It's dynamical. It's not like the backdrop for everything. Instead, 326 00:17:14,960 --> 00:17:17,479 Speaker 1: it's in this dance with matter. Right. When you have 327 00:17:17,600 --> 00:17:21,320 Speaker 1: matter and energy around, space bends and it curves, and 328 00:17:21,359 --> 00:17:24,040 Speaker 1: it can do weird things like it can ripple, right, 329 00:17:24,119 --> 00:17:26,240 Speaker 1: and it can expand. And this is the things that 330 00:17:26,280 --> 00:17:29,280 Speaker 1: we see, like we see ripples in space. We know 331 00:17:29,400 --> 00:17:32,879 Speaker 1: that this general relativity picture is at least approximately correct. 332 00:17:32,880 --> 00:17:35,400 Speaker 1: It might not be the fundamental theory of the universe, 333 00:17:35,560 --> 00:17:39,000 Speaker 1: but it's really accurate. It predicts these gravitational waves and 334 00:17:39,040 --> 00:17:42,600 Speaker 1: we see them. It can accommodate at least the accelerated 335 00:17:42,640 --> 00:17:46,200 Speaker 1: expansion of the universe in terms of a cosmological constant. 336 00:17:46,320 --> 00:17:49,359 Speaker 1: We don't understand why that's there, what's happening, etcetera, but 337 00:17:49,400 --> 00:17:52,119 Speaker 1: it can be accommodated in general relativity. So it's very 338 00:17:52,119 --> 00:17:56,159 Speaker 1: successful description of how matter and space interact. And it 339 00:17:56,280 --> 00:17:58,399 Speaker 1: suggests that space is not fundamental, that it sort of 340 00:17:58,400 --> 00:18:00,800 Speaker 1: states at the same level as matter our energy, because 341 00:18:00,840 --> 00:18:03,600 Speaker 1: the too sort of have this feedback loop between each other. 342 00:18:04,000 --> 00:18:06,600 Speaker 1: Basically says that space is a thing, right like, it's 343 00:18:06,600 --> 00:18:10,919 Speaker 1: not static, it doesn't exist, it doesn't ignore matter, you know, 344 00:18:11,040 --> 00:18:13,600 Speaker 1: like it responds to matter, and you know, it's not 345 00:18:13,680 --> 00:18:16,760 Speaker 1: independent of matter exactly. And you can do these weird 346 00:18:16,800 --> 00:18:19,160 Speaker 1: things that we never imagined that it could do, which 347 00:18:19,200 --> 00:18:21,679 Speaker 1: means it might be able to do other weird things 348 00:18:21,760 --> 00:18:25,240 Speaker 1: we also hadn't yet had the imagination to do. Anytime, 349 00:18:25,240 --> 00:18:28,080 Speaker 1: we're limited by our imagination. I'm always skeptical that we've 350 00:18:28,160 --> 00:18:31,399 Speaker 1: thought of everything. I know, the theorists are very smart, 351 00:18:31,440 --> 00:18:33,800 Speaker 1: and even our science fiction authors are always pushing the 352 00:18:33,840 --> 00:18:36,520 Speaker 1: boundaries of creativity when it comes to like, you know, 353 00:18:36,600 --> 00:18:40,159 Speaker 1: intellectual concepts. But there's always the possibility that there's always 354 00:18:40,160 --> 00:18:42,240 Speaker 1: something else out there we just haven't thought of that 355 00:18:42,280 --> 00:18:44,960 Speaker 1: could be happening in our universe. So space could have 356 00:18:45,080 --> 00:18:49,040 Speaker 1: really weird properties that we never imagined. Imagine, for example, 357 00:18:49,119 --> 00:18:52,480 Speaker 1: being a scientist that's a fish swimming through water all 358 00:18:52,520 --> 00:18:54,920 Speaker 1: the time and not realizing, you know, that space could end, 359 00:18:55,280 --> 00:18:58,040 Speaker 1: or that your water wasn't actually fundamental, and they could 360 00:18:58,040 --> 00:19:00,760 Speaker 1: do other weird things like boil and turn into a gas. 361 00:19:01,200 --> 00:19:03,920 Speaker 1: You know, space like that could have other phases, other 362 00:19:03,960 --> 00:19:06,840 Speaker 1: weird properties we just haven't observed yet, and so we 363 00:19:06,880 --> 00:19:09,440 Speaker 1: assume are impossible because I guess, once you can get 364 00:19:09,600 --> 00:19:12,560 Speaker 1: space to bend or ripple or expand then who knows 365 00:19:12,560 --> 00:19:14,399 Speaker 1: what you can make it do? Who knows what you 366 00:19:14,440 --> 00:19:17,399 Speaker 1: can make it do exactly? And the solutions to general 367 00:19:17,400 --> 00:19:19,959 Speaker 1: relativity are so complicated and difficult, and that it's not 368 00:19:20,040 --> 00:19:23,600 Speaker 1: possible to conceive of all the possible configurations that are 369 00:19:23,600 --> 00:19:26,080 Speaker 1: consistent with it. Those are the two views of space. 370 00:19:26,160 --> 00:19:28,879 Speaker 1: One says that it's something that you know, can't touch 371 00:19:29,080 --> 00:19:31,080 Speaker 1: or that you live on top of, and the other 372 00:19:31,119 --> 00:19:33,120 Speaker 1: one says that it's something that it's more of a thing, 373 00:19:33,200 --> 00:19:36,280 Speaker 1: like it's dynamic and you can manipulate it and it 374 00:19:36,359 --> 00:19:39,240 Speaker 1: can change, So that those are the two basic views 375 00:19:39,240 --> 00:19:41,679 Speaker 1: about space, right, But it doesn't sort of explain what 376 00:19:41,840 --> 00:19:45,000 Speaker 1: space is. It's just sort of like how you regard space. Yeah, 377 00:19:45,000 --> 00:19:47,479 Speaker 1: but that's sort of what space is. You know, space 378 00:19:47,560 --> 00:19:50,199 Speaker 1: is how we treat it. Some people might say space 379 00:19:50,280 --> 00:19:54,000 Speaker 1: is just like a mathematical construct in our minds. You know, 380 00:19:54,080 --> 00:19:57,600 Speaker 1: that's not actually something that's physical. For example, in quantum mechanics, 381 00:19:57,720 --> 00:20:01,240 Speaker 1: we never deal with space itself directly, right, All we 382 00:20:01,320 --> 00:20:04,280 Speaker 1: ever do is deal with the fields in space. We 383 00:20:04,400 --> 00:20:07,600 Speaker 1: never like interact with space itself, and so it's sort 384 00:20:07,600 --> 00:20:10,359 Speaker 1: of like just an abstraction. It's just like a way 385 00:20:10,359 --> 00:20:13,800 Speaker 1: of thinking about organizing these fields. Whereas in general relativity, 386 00:20:13,920 --> 00:20:16,439 Speaker 1: like spaces the thing. It's the thing that's keeping us 387 00:20:16,480 --> 00:20:19,520 Speaker 1: on the Earth. It explains gravity, which is pretty important. 388 00:20:19,640 --> 00:20:22,119 Speaker 1: So you know, how we represent them in our theories 389 00:20:22,200 --> 00:20:24,040 Speaker 1: goes a long way to telling you what we think 390 00:20:24,080 --> 00:20:26,159 Speaker 1: they are. All right, Well, I think that sets the 391 00:20:26,200 --> 00:20:30,080 Speaker 1: space for a deeper discussion about space and whether or 392 00:20:30,119 --> 00:20:32,280 Speaker 1: not Daniel can through it in the dumpster or not. 393 00:20:32,480 --> 00:20:36,639 Speaker 1: Please please please, please, please please please. I would be 394 00:20:36,680 --> 00:20:40,240 Speaker 1: so offended if I was space right now, I would 395 00:20:40,359 --> 00:20:43,760 Speaker 1: limit your space Daniel. But let's get into that question 396 00:20:43,800 --> 00:20:46,440 Speaker 1: and also whether or not we will ever be able 397 00:20:46,520 --> 00:20:49,560 Speaker 1: to know what the answer is. But first, let's take 398 00:20:49,600 --> 00:21:05,119 Speaker 1: a quick break. All right, we're talking about space and 399 00:21:05,160 --> 00:21:07,560 Speaker 1: whether or not we can just toss it out, Daniel, 400 00:21:07,800 --> 00:21:10,840 Speaker 1: I feel like that's so unappreciative. How can you just 401 00:21:11,000 --> 00:21:14,439 Speaker 1: throw the thing out that you know you grew up in. Well, 402 00:21:14,480 --> 00:21:16,320 Speaker 1: you know, let's make a distinction here. We are, of 403 00:21:16,359 --> 00:21:19,880 Speaker 1: course searching to explain space, to figure out whether it's 404 00:21:19,920 --> 00:21:23,160 Speaker 1: the basic ingredient of the universe or whether it emerges 405 00:21:23,200 --> 00:21:25,320 Speaker 1: from something else. But that's not to say the things 406 00:21:25,359 --> 00:21:29,760 Speaker 1: that emerge are uninteresting or unimportant. Right, Like, the entire 407 00:21:29,800 --> 00:21:34,320 Speaker 1: field of biology is emergent in the sense that you could, 408 00:21:34,359 --> 00:21:38,080 Speaker 1: in principle, calculated all from fundamental particles. But that's not 409 00:21:38,160 --> 00:21:41,439 Speaker 1: like a smart way to do biology. Nobody would anybody 410 00:21:41,520 --> 00:21:44,160 Speaker 1: does do biology from the particle perspective. I just want 411 00:21:44,160 --> 00:21:46,440 Speaker 1: to make sure people don't think that we're being negative 412 00:21:46,440 --> 00:21:50,239 Speaker 1: about emergent phenomena. They're fascinating, they're amazing, they're incredible. We 413 00:21:50,280 --> 00:21:52,639 Speaker 1: are emergent phenomena. It's just, you know, part of this 414 00:21:52,760 --> 00:21:55,359 Speaker 1: question of getting down, drilling down to the deepest nature 415 00:21:55,400 --> 00:21:58,520 Speaker 1: of reality is to ask what's fundamental and what's emergent, 416 00:21:58,680 --> 00:22:00,720 Speaker 1: not necessarily to judge them. You just want to add 417 00:22:00,720 --> 00:22:03,960 Speaker 1: your bets and not offend your spouse's biologist. I have 418 00:22:04,040 --> 00:22:07,320 Speaker 1: the deepest of respects for my spouse and also for biology, 419 00:22:07,359 --> 00:22:10,760 Speaker 1: which is not your furniture. Just not my furniture, absolutely 420 00:22:11,560 --> 00:22:14,000 Speaker 1: all right. So there are two perspectives about space. It 421 00:22:14,040 --> 00:22:17,240 Speaker 1: seems like quantum mechanics doesn't say anything about space other 422 00:22:17,280 --> 00:22:20,040 Speaker 1: than it's there and you can't mess with it, and 423 00:22:20,119 --> 00:22:22,640 Speaker 1: general relativity says that it's something that you can sort 424 00:22:22,640 --> 00:22:25,160 Speaker 1: of mess with and change and bend. And I guess 425 00:22:25,200 --> 00:22:29,159 Speaker 1: the question is are those two things incompatible or is 426 00:22:29,160 --> 00:22:31,200 Speaker 1: there a sort of a fundamental conflict about them? Like 427 00:22:31,240 --> 00:22:35,200 Speaker 1: couldn't you have quantum mechanics sit on top of general relativity? Yeah, exactly, 428 00:22:35,560 --> 00:22:38,960 Speaker 1: And people are working on exactly that, trying to unify 429 00:22:39,240 --> 00:22:43,320 Speaker 1: general relativity and quantum mechanics in several different ways, and 430 00:22:43,359 --> 00:22:46,560 Speaker 1: in doing so, they're giving us hints about answers to 431 00:22:46,600 --> 00:22:50,119 Speaker 1: this question about whether space is fundamental or not. Like 432 00:22:50,119 --> 00:22:52,399 Speaker 1: when they put these two things together, they basically have 433 00:22:52,480 --> 00:22:54,640 Speaker 1: to make a decision like, well, do we have spaces 434 00:22:54,680 --> 00:22:56,919 Speaker 1: the list of fundamental ingredients in our new theory of 435 00:22:57,200 --> 00:23:01,160 Speaker 1: quantum gravity or not. And there's a couple of different approaches. 436 00:23:01,359 --> 00:23:04,439 Speaker 1: One is sort of like make gravity a quantum theory, 437 00:23:04,560 --> 00:23:07,600 Speaker 1: thinking about it as like just another quantum force that 438 00:23:07,880 --> 00:23:12,320 Speaker 1: exchanges particles the gravitons in order to make gravity happen, 439 00:23:12,440 --> 00:23:15,200 Speaker 1: and sort of making quantum mechanics primary. And the other 440 00:23:15,359 --> 00:23:18,120 Speaker 1: is to try to quantize gravity itself, you know, either 441 00:23:18,200 --> 00:23:21,840 Speaker 1: make the universe into little pixels or take the gravitational 442 00:23:21,920 --> 00:23:24,359 Speaker 1: field and make a discreet and so that would make 443 00:23:24,359 --> 00:23:27,600 Speaker 1: a general relativity sort of at the primary foundational level 444 00:23:27,760 --> 00:23:30,640 Speaker 1: of these new theories of quantum gravity, and which direction 445 00:23:30,680 --> 00:23:33,760 Speaker 1: you go sort of dictates the fate of the idea 446 00:23:33,880 --> 00:23:37,160 Speaker 1: of space and whether it's fundamental or emergent. I guess 447 00:23:37,200 --> 00:23:40,080 Speaker 1: maybe one difference is that like in general relativity, if 448 00:23:40,080 --> 00:23:43,240 Speaker 1: you have a speck of dust, it's technically bending the 449 00:23:43,280 --> 00:23:45,760 Speaker 1: space around it. But in quantum mechanics, if you have 450 00:23:45,840 --> 00:23:48,600 Speaker 1: like a proton or an electron, it's not really bending 451 00:23:48,640 --> 00:23:50,879 Speaker 1: space around it. Right, In quantum mechanics, we have no 452 00:23:51,000 --> 00:23:55,800 Speaker 1: description of the curvature of space that works, right, So yeah, absolutely, 453 00:23:55,800 --> 00:23:59,159 Speaker 1: we don't have a quantum mechanical description of gravity or 454 00:23:59,240 --> 00:24:02,119 Speaker 1: the bending of space, so we can't describe how space 455 00:24:02,160 --> 00:24:04,480 Speaker 1: has bent around of dust particle. We know that it 456 00:24:04,640 --> 00:24:06,840 Speaker 1: is though, right we think that that's true. One of 457 00:24:06,880 --> 00:24:09,720 Speaker 1: the difficulties is that we can't test these things very 458 00:24:09,760 --> 00:24:13,520 Speaker 1: well because particles have very very small amounts of gravity. 459 00:24:13,800 --> 00:24:17,040 Speaker 1: Member gravity so much weaker than all the other forces, 460 00:24:17,119 --> 00:24:20,320 Speaker 1: like ten to the thirty times weaker. So we can't 461 00:24:20,359 --> 00:24:23,160 Speaker 1: really test these things because all the other forces dominate. 462 00:24:23,320 --> 00:24:25,760 Speaker 1: Two protons, for example, coming together, the large Hage and 463 00:24:25,800 --> 00:24:29,000 Speaker 1: collider feel almost no gravity in comparison to the strong 464 00:24:29,080 --> 00:24:32,080 Speaker 1: and the weak and the electromagnetic forces, So it's very 465 00:24:32,080 --> 00:24:34,439 Speaker 1: hard to do an experiment at the particle level that 466 00:24:34,560 --> 00:24:37,280 Speaker 1: tests gravity. I guess maybe then to get back to 467 00:24:37,280 --> 00:24:40,119 Speaker 1: our question, then what do these two theories say about 468 00:24:40,200 --> 00:24:44,080 Speaker 1: the idea of having no space? Like could you have 469 00:24:44,160 --> 00:24:47,720 Speaker 1: no space in plantum mechanics or general relativity or is 470 00:24:47,720 --> 00:24:50,280 Speaker 1: that impossible according to the theories. So there are now 471 00:24:50,440 --> 00:24:54,480 Speaker 1: really fun ideas about how space might not be fundamental, 472 00:24:54,520 --> 00:24:59,280 Speaker 1: how you could have a universe without space in quantum mechanics. 473 00:24:59,359 --> 00:25:01,800 Speaker 1: And I think these ideas are really cool because they 474 00:25:01,840 --> 00:25:04,159 Speaker 1: make us think about quantum mechanics sort of at a 475 00:25:04,200 --> 00:25:07,560 Speaker 1: more basic level. You know, we think about the wave function. 476 00:25:07,640 --> 00:25:10,320 Speaker 1: For example. Wave function is like this basic element of 477 00:25:10,359 --> 00:25:13,600 Speaker 1: quantum mechanics. It tells you what's going to happen to 478 00:25:13,640 --> 00:25:16,720 Speaker 1: a particle, or for example, where a particle might be. 479 00:25:16,960 --> 00:25:19,440 Speaker 1: If you have a question about the outcome of your experiment, 480 00:25:19,600 --> 00:25:22,400 Speaker 1: the wave function tells you this outcome has a certain probability, 481 00:25:22,440 --> 00:25:25,800 Speaker 1: and that outcome has another probability. And typically we think 482 00:25:25,840 --> 00:25:29,399 Speaker 1: about the wave function as distributed across space, like is 483 00:25:29,440 --> 00:25:32,080 Speaker 1: the electron here or is the electron there, But in 484 00:25:32,119 --> 00:25:36,359 Speaker 1: principle it can be distributed across abstract states also, you know, 485 00:25:36,440 --> 00:25:40,160 Speaker 1: like the electron spin or the outcome of your experiment, 486 00:25:40,320 --> 00:25:43,040 Speaker 1: or all sorts of other kinds of things. And so 487 00:25:43,080 --> 00:25:45,399 Speaker 1: it's not hard for us to sort of augment the 488 00:25:45,520 --> 00:25:49,240 Speaker 1: current concept of space with these like abstract spaces. We 489 00:25:49,280 --> 00:25:52,639 Speaker 1: call them Hilbert spaces in which the wave function lives. 490 00:25:52,880 --> 00:25:55,560 Speaker 1: And it might be that those Hilbert spaces are the 491 00:25:55,600 --> 00:25:58,199 Speaker 1: actual primary thing that we can sort of let go 492 00:25:58,840 --> 00:26:02,080 Speaker 1: of these concepts of position and based the whole existence 493 00:26:02,080 --> 00:26:04,880 Speaker 1: of the universe just on those sort of abstract spaces 494 00:26:04,920 --> 00:26:07,160 Speaker 1: than the ones that are not physical, that don't represent 495 00:26:07,240 --> 00:26:10,640 Speaker 1: actual locations, that are not anywhere. I think what you're 496 00:26:10,640 --> 00:26:13,960 Speaker 1: saying is that, like maybe space, according to the theory, 497 00:26:14,119 --> 00:26:17,879 Speaker 1: is not like a physical thing or physical space, but 498 00:26:17,960 --> 00:26:21,159 Speaker 1: it's rather just sort of like a mathematical concept or 499 00:26:21,520 --> 00:26:23,800 Speaker 1: set of relationships. Is that what you mean. Yeah, we 500 00:26:23,880 --> 00:26:26,560 Speaker 1: know that it's a set of relationships. As we said earlier, 501 00:26:26,600 --> 00:26:30,280 Speaker 1: in quantum mechanics, we never actually interact with space. All 502 00:26:30,320 --> 00:26:33,120 Speaker 1: we do is we see sort of the propagation of 503 00:26:33,359 --> 00:26:37,760 Speaker 1: information through fields as that information moves through space. But 504 00:26:37,880 --> 00:26:40,600 Speaker 1: really that information is moving through the field, and so 505 00:26:40,640 --> 00:26:42,880 Speaker 1: you can think about it in terms of like pieces 506 00:26:42,920 --> 00:26:45,200 Speaker 1: of space that are sort of woven together. So it's 507 00:26:45,240 --> 00:26:49,239 Speaker 1: like the relationships between different elements of the field, and 508 00:26:49,280 --> 00:26:52,240 Speaker 1: the space itself is really just like the relationship between 509 00:26:52,280 --> 00:26:55,080 Speaker 1: those elements. So this one is far away from that one, 510 00:26:55,160 --> 00:26:57,879 Speaker 1: or this one is close to that one. So you 511 00:26:57,880 --> 00:26:59,919 Speaker 1: don't have to have those bits of the field like 512 00:27:00,359 --> 00:27:04,240 Speaker 1: hanging in an absolute, actually existing space. It might just 513 00:27:04,320 --> 00:27:07,520 Speaker 1: be that they have those relationships in another way and 514 00:27:07,560 --> 00:27:10,240 Speaker 1: woven together that gives the same effect as if they 515 00:27:10,240 --> 00:27:12,680 Speaker 1: were actually in a space. I wonder if it's sort 516 00:27:12,680 --> 00:27:15,760 Speaker 1: of like the concept of money. You know, like something 517 00:27:16,240 --> 00:27:18,719 Speaker 1: is worth more or has a bigger price on it 518 00:27:18,840 --> 00:27:21,439 Speaker 1: just because it doesn't mean that it has more energy 519 00:27:21,480 --> 00:27:23,800 Speaker 1: to it or more matter to it, or you know, 520 00:27:23,960 --> 00:27:26,800 Speaker 1: sits closer to you, or you can do more things 521 00:27:26,800 --> 00:27:29,200 Speaker 1: with it. It's just so happens that this thing has 522 00:27:29,240 --> 00:27:31,240 Speaker 1: a labeled with a big price on it, and that 523 00:27:31,240 --> 00:27:33,239 Speaker 1: that one has a labeled with a lower price on it. 524 00:27:33,560 --> 00:27:35,280 Speaker 1: Is that kind of what you mean, Like, maybe space 525 00:27:35,359 --> 00:27:39,360 Speaker 1: is really just like the economy of the yeah, exactly. 526 00:27:39,359 --> 00:27:41,159 Speaker 1: And you can also think about it in terms of 527 00:27:41,160 --> 00:27:44,439 Speaker 1: like your networks. Think about your relationships with your family. 528 00:27:44,440 --> 00:27:47,240 Speaker 1: Who are you close to We even use that word close, right, 529 00:27:47,560 --> 00:27:50,399 Speaker 1: Even if you're physically far away from somebody else, you 530 00:27:50,480 --> 00:27:53,600 Speaker 1: have a network of people that you interact with who 531 00:27:53,800 --> 00:27:55,960 Speaker 1: know you very well, and then people who are distant, 532 00:27:56,000 --> 00:27:59,000 Speaker 1: and then people who are basically super impossibly far away. Well, 533 00:27:59,000 --> 00:28:01,120 Speaker 1: it might be that that sort of like the fundamental 534 00:28:01,160 --> 00:28:04,520 Speaker 1: definition of who you are and what your spaces rather 535 00:28:04,560 --> 00:28:07,360 Speaker 1: than like where you actually are sitting in your bedroom 536 00:28:07,480 --> 00:28:10,920 Speaker 1: or in Los Angeles or in Germany or wherever. Maybe 537 00:28:10,920 --> 00:28:13,400 Speaker 1: space is just an emotional space, you know what I mean? 538 00:28:13,520 --> 00:28:19,000 Speaker 1: Like space is really just the emotional currency of your relationships. Yeah, 539 00:28:19,040 --> 00:28:21,159 Speaker 1: and these are just analogies we're using to try to 540 00:28:21,320 --> 00:28:24,480 Speaker 1: get your mind away from this primacy of space that 541 00:28:24,480 --> 00:28:27,240 Speaker 1: we've been assuming and thinking about the universe as built 542 00:28:27,240 --> 00:28:29,920 Speaker 1: out of things that don't hang in space but still 543 00:28:30,000 --> 00:28:33,600 Speaker 1: have relationships with each other, and then those relationships are 544 00:28:33,640 --> 00:28:36,159 Speaker 1: what space emerges from. And we can actually do this 545 00:28:36,240 --> 00:28:40,200 Speaker 1: not just by doing analogies to social media, but actually mathematically, 546 00:28:40,200 --> 00:28:42,880 Speaker 1: and people have taken the way function of the universe. 547 00:28:42,920 --> 00:28:45,680 Speaker 1: For example, think about, like what is a quantum mechanical 548 00:28:45,680 --> 00:28:48,720 Speaker 1: description of the whole universe? Can you describe everything in 549 00:28:48,760 --> 00:28:51,200 Speaker 1: the universe and you don't have to necessarily put them 550 00:28:51,240 --> 00:28:54,320 Speaker 1: in a location, you know, just say there's a probability 551 00:28:54,400 --> 00:28:56,760 Speaker 1: for this particle and probably for that particle, and then 552 00:28:56,840 --> 00:28:59,840 Speaker 1: link them together and say, well, this one is entangled 553 00:29:00,120 --> 00:29:03,760 Speaker 1: that one. This concept of quantum entanglement of particles having 554 00:29:03,800 --> 00:29:06,200 Speaker 1: like their fates connected to each other because they have 555 00:29:06,240 --> 00:29:10,040 Speaker 1: a common past. This entanglement might provide that weave, It 556 00:29:10,080 --> 00:29:13,040 Speaker 1: might provide the connection between like the bits of the 557 00:29:13,120 --> 00:29:16,240 Speaker 1: universe that when you weave them together, some things are 558 00:29:16,240 --> 00:29:19,600 Speaker 1: more entangled than others, and so they seem closer together, 559 00:29:19,680 --> 00:29:22,480 Speaker 1: and other things are less entangled, and so they seem 560 00:29:22,520 --> 00:29:25,120 Speaker 1: more distant. It might be that this quantum entanglement are 561 00:29:25,160 --> 00:29:28,520 Speaker 1: those same relationships that connect these bits of the wave 562 00:29:28,560 --> 00:29:31,040 Speaker 1: function that make it seem as if it is hanging 563 00:29:31,040 --> 00:29:33,840 Speaker 1: in some space. And this sort of set of relationships 564 00:29:33,920 --> 00:29:37,600 Speaker 1: or currency or valuations, that's what you call these Hilbert 565 00:29:37,640 --> 00:29:40,160 Speaker 1: spaces or is that different? The Hilbert space is the 566 00:29:40,200 --> 00:29:43,040 Speaker 1: set of possible wave functions that you can have, and 567 00:29:43,080 --> 00:29:46,800 Speaker 1: then the relationships between the different wave functions that are disconnected, 568 00:29:46,920 --> 00:29:49,560 Speaker 1: those are the entanglements. Those come together to make this 569 00:29:49,600 --> 00:29:52,680 Speaker 1: sort of like grand weave that we call space. And 570 00:29:52,680 --> 00:29:54,440 Speaker 1: if this is true, it doesn't mean that space is 571 00:29:54,480 --> 00:29:57,840 Speaker 1: not like real. It just means that it comes from 572 00:29:57,960 --> 00:30:00,520 Speaker 1: something else, you know, that it bubbles up from something 573 00:30:00,560 --> 00:30:03,680 Speaker 1: more primary, just like air is real, even if it's 574 00:30:03,680 --> 00:30:06,239 Speaker 1: not fundamental to the universe. You can still breathe it. 575 00:30:06,240 --> 00:30:09,120 Speaker 1: It's still very nice on a nice, fresh windy day 576 00:30:09,200 --> 00:30:12,520 Speaker 1: in Los Angeles. Come on, never happens. But I guess 577 00:30:12,520 --> 00:30:15,840 Speaker 1: maybe a question is what's the difference? You know, like 578 00:30:15,880 --> 00:30:18,239 Speaker 1: the word Hilbert space still has the word space in it, 579 00:30:19,000 --> 00:30:21,520 Speaker 1: So like what would be the difference between a Hilbert 580 00:30:21,520 --> 00:30:26,320 Speaker 1: space or these abstract connection space and maybe a more 581 00:30:26,400 --> 00:30:31,239 Speaker 1: regular definition of space. Well, our four dimensional space has 582 00:30:31,280 --> 00:30:34,239 Speaker 1: certain properties. You know, information transforms through it in a 583 00:30:34,240 --> 00:30:36,400 Speaker 1: certain way. It follows the speed of light. There are 584 00:30:36,480 --> 00:30:40,520 Speaker 1: four dimensions, including time. An abstract Hilbert space is much 585 00:30:40,560 --> 00:30:43,320 Speaker 1: broader and more general, like it can be infinite dimensional. 586 00:30:43,680 --> 00:30:47,440 Speaker 1: You can have complex values, you know, imaginary numbers, all 587 00:30:47,480 --> 00:30:49,400 Speaker 1: sorts of things. So this is sort of like a 588 00:30:49,480 --> 00:30:52,760 Speaker 1: subset of all the possible Hilbert spaces. It's like it 589 00:30:52,840 --> 00:30:55,760 Speaker 1: turns out that the relationship between all these quantum wave 590 00:30:55,800 --> 00:30:59,760 Speaker 1: functions can be described in this sort of simpler subspace, 591 00:31:00,120 --> 00:31:03,440 Speaker 1: this four dimensional subspace, in which all that information can 592 00:31:03,480 --> 00:31:06,400 Speaker 1: be mapped onto the whole hill of beans. It's the 593 00:31:06,400 --> 00:31:09,040 Speaker 1: whole hill of beans. But it also means other interesting things. 594 00:31:09,080 --> 00:31:11,640 Speaker 1: If this is true. It means that, for example, you 595 00:31:11,680 --> 00:31:15,800 Speaker 1: could have different spaces inside this, like larger Hilbert space. 596 00:31:15,800 --> 00:31:18,200 Speaker 1: You can have like our chunk of space which is 597 00:31:18,200 --> 00:31:20,920 Speaker 1: all woven together, and you could have another one somewhere 598 00:31:20,920 --> 00:31:24,440 Speaker 1: else was also emerged and is totally disconnected from ours, 599 00:31:24,600 --> 00:31:27,840 Speaker 1: and you could have maybe parts of it without these relationships, right, 600 00:31:27,880 --> 00:31:30,320 Speaker 1: Like you could have a whole bunch of people with 601 00:31:30,360 --> 00:31:34,560 Speaker 1: no friends on Facebook exactly, or even parts of the 602 00:31:34,600 --> 00:31:38,240 Speaker 1: world where there is no Facebook. Hard to imagine, right, 603 00:31:38,640 --> 00:31:41,240 Speaker 1: but it might be true. And so if this picture 604 00:31:41,320 --> 00:31:43,920 Speaker 1: is accurate, then the answer is absolutely you can have 605 00:31:43,960 --> 00:31:46,600 Speaker 1: the universe without space. It's not necessarily clear that you 606 00:31:46,680 --> 00:31:49,000 Speaker 1: need space to have the universe. And you can have 607 00:31:49,040 --> 00:31:51,280 Speaker 1: parts of the universe with space, parts of the universe 608 00:31:51,320 --> 00:31:54,560 Speaker 1: without space, and other parts of the universe you know 609 00:31:54,640 --> 00:31:56,960 Speaker 1: that have different kinds of spaces. And you might be thinking, 610 00:31:57,040 --> 00:31:59,240 Speaker 1: hold on, he's saying the word parts. What does he 611 00:31:59,320 --> 00:32:02,600 Speaker 1: mean if there's no space, what parts is he talking about? 612 00:32:02,720 --> 00:32:05,920 Speaker 1: And again, you know, these parts don't necessarily have like 613 00:32:05,960 --> 00:32:08,680 Speaker 1: a spatial relationship. You can't say this one is here 614 00:32:08,880 --> 00:32:11,000 Speaker 1: and that one is there in the sense of like 615 00:32:11,280 --> 00:32:14,239 Speaker 1: where is your family? You know, you guys might be 616 00:32:14,240 --> 00:32:17,800 Speaker 1: physically somewhere, but the actual relationships between you, those connections 617 00:32:17,800 --> 00:32:20,600 Speaker 1: that tie you together, like where is that It isn't 618 00:32:20,640 --> 00:32:23,320 Speaker 1: really anywhere, It just sort of in your emotional space. Yes, 619 00:32:23,360 --> 00:32:25,440 Speaker 1: if you can't find your family, that's a whole different 620 00:32:25,480 --> 00:32:28,920 Speaker 1: problem there, and a whole different type of podcast. There's 621 00:32:28,920 --> 00:32:30,520 Speaker 1: the whole genre for that. But that's sort of the 622 00:32:30,600 --> 00:32:33,840 Speaker 1: quantum mechanical view. If you say quantum mechanics is primary 623 00:32:34,120 --> 00:32:36,200 Speaker 1: and the way function for the universe is the most 624 00:32:36,200 --> 00:32:39,600 Speaker 1: basic thing, then can you build up a universe without spaces? 625 00:32:39,640 --> 00:32:42,880 Speaker 1: Space necessary? That's the quantum mechanical path, right, And it 626 00:32:42,880 --> 00:32:44,959 Speaker 1: sounds like the answer is sort of yes, Like if 627 00:32:45,040 --> 00:32:48,000 Speaker 1: quantum mechanics is all there is, then it might be 628 00:32:48,120 --> 00:32:51,760 Speaker 1: possible to see how you could not have space absolutely. 629 00:32:51,840 --> 00:32:54,640 Speaker 1: And there's some really fun recent ideas things called like 630 00:32:54,920 --> 00:32:59,160 Speaker 1: condensate cosmology, where space condenses in these like steam like 631 00:32:59,360 --> 00:33:03,080 Speaker 1: droplets from these weird fun spin networks that are more fundamental, 632 00:33:03,160 --> 00:33:05,360 Speaker 1: but we're gonna do a whole podcast about that sometime 633 00:33:05,400 --> 00:33:07,560 Speaker 1: in the future. Well all right, well then, and now, 634 00:33:07,600 --> 00:33:10,960 Speaker 1: what does general relativity say about not having any space? 635 00:33:11,040 --> 00:33:13,960 Speaker 1: Is that possible? According to that view, general relativity really 636 00:33:14,000 --> 00:33:18,720 Speaker 1: has no problem with space not existing because in our 637 00:33:18,880 --> 00:33:23,280 Speaker 1: general relativistic understanding of the universe, think about what happens 638 00:33:23,280 --> 00:33:25,880 Speaker 1: in the history, Right, we have the current universe. We 639 00:33:25,960 --> 00:33:28,440 Speaker 1: look back in time and we see the universe getting 640 00:33:28,440 --> 00:33:31,640 Speaker 1: more and more compact, and we propagate back and further 641 00:33:31,720 --> 00:33:36,240 Speaker 1: and further and further and approaches this special moment, this singularity, 642 00:33:36,480 --> 00:33:40,280 Speaker 1: this time before which space does not exist. And you know, 643 00:33:40,320 --> 00:33:42,640 Speaker 1: there are various ideas for how to tackle that and 644 00:33:42,680 --> 00:33:44,560 Speaker 1: what that means and if it's a breakdown of the 645 00:33:44,560 --> 00:33:46,760 Speaker 1: theory and if it needs to be replaced by something else. 646 00:33:47,080 --> 00:33:52,240 Speaker 1: But in our current albeit imperfect, non quantum mechanical general relativity, 647 00:33:52,280 --> 00:33:55,640 Speaker 1: there is this concept that there is no space before 648 00:33:55,840 --> 00:33:59,520 Speaker 1: the Big Bang, there's no space or it was just 649 00:33:59,600 --> 00:34:03,080 Speaker 1: super compressed. It's super compressed in the very first moments 650 00:34:03,120 --> 00:34:07,200 Speaker 1: of the universe, but before that, before the singularity itself, right, 651 00:34:07,240 --> 00:34:10,560 Speaker 1: this moment of infinite density, that space did not exist. 652 00:34:10,560 --> 00:34:13,640 Speaker 1: That it doesn't make sense to ask where is something 653 00:34:13,760 --> 00:34:16,800 Speaker 1: or when is something because the whole notion of space 654 00:34:16,840 --> 00:34:20,319 Speaker 1: and time came into existence then, like there is no 655 00:34:20,440 --> 00:34:22,959 Speaker 1: space and time before then. And this is not something 656 00:34:23,000 --> 00:34:25,279 Speaker 1: that's very easy to think about because we don't think 657 00:34:25,280 --> 00:34:28,840 Speaker 1: about space and definitely not time beginning right, But a 658 00:34:28,880 --> 00:34:31,440 Speaker 1: whole other podcast episode about whether you need time and 659 00:34:31,480 --> 00:34:34,680 Speaker 1: if time is an emergent phenomena. It's a whole even 660 00:34:34,760 --> 00:34:37,279 Speaker 1: more difficult question to grapple with because you have to 661 00:34:37,320 --> 00:34:39,839 Speaker 1: think about, like, could there be a time before which 662 00:34:39,880 --> 00:34:42,640 Speaker 1: there was no time. But putting that aside for the 663 00:34:42,719 --> 00:34:45,520 Speaker 1: time being, at least, it's hard still to think about 664 00:34:45,560 --> 00:34:48,200 Speaker 1: a universe existing without space. But if you can still 665 00:34:48,200 --> 00:34:50,760 Speaker 1: have time, right, if you say time exists, but maybe 666 00:34:50,800 --> 00:34:53,759 Speaker 1: space is not fundamental, it might make sense to you 667 00:34:53,760 --> 00:34:56,399 Speaker 1: to think about like space itself is this weird thing 668 00:34:56,440 --> 00:34:59,279 Speaker 1: we talked about, this weird do that does stuff, and 669 00:34:59,320 --> 00:35:01,920 Speaker 1: it can bubble and it can expand. It's being created 670 00:35:02,040 --> 00:35:04,720 Speaker 1: right now. If it's being created, then you know, maybe 671 00:35:04,719 --> 00:35:07,480 Speaker 1: there was a moment before it was created, or you know, 672 00:35:07,560 --> 00:35:10,200 Speaker 1: you can think about what is there when it's not 673 00:35:10,280 --> 00:35:13,560 Speaker 1: being created right and there's there's no space, if there's 674 00:35:13,560 --> 00:35:16,080 Speaker 1: no space being created exactly, and it might be that 675 00:35:16,280 --> 00:35:19,120 Speaker 1: you can have a universe before space is created. Might 676 00:35:19,120 --> 00:35:22,040 Speaker 1: be the time existed before the Big Bang, but just 677 00:35:22,080 --> 00:35:26,840 Speaker 1: not space. And there's some like conditions required for space 678 00:35:26,880 --> 00:35:29,680 Speaker 1: to be created for it to expand. Like you might 679 00:35:29,680 --> 00:35:32,080 Speaker 1: think it's a weird concept for space to be created, 680 00:35:32,080 --> 00:35:35,000 Speaker 1: but remember that it's happening right now. You know, the 681 00:35:35,000 --> 00:35:38,440 Speaker 1: expansion of the universe is not the motion of stuff 682 00:35:38,560 --> 00:35:42,040 Speaker 1: through the universe. It's the creation of new space between 683 00:35:42,160 --> 00:35:45,280 Speaker 1: us and other galaxies, between you and your couch between 684 00:35:45,280 --> 00:35:48,719 Speaker 1: everything and everything else. So it's happening right now. And 685 00:35:49,080 --> 00:35:51,840 Speaker 1: it's just that we have only recently realized that space 686 00:35:51,960 --> 00:35:54,480 Speaker 1: is this bizarre fabric that can do these things like 687 00:35:54,680 --> 00:35:59,480 Speaker 1: be created spontaneously everywhere simultaneously, that we've come to ask 688 00:35:59,520 --> 00:36:01,360 Speaker 1: these quests, and so we just really don't have a 689 00:36:01,440 --> 00:36:05,359 Speaker 1: notion and understanding of what space is even in general relativity. 690 00:36:05,480 --> 00:36:07,720 Speaker 1: But it's certainly is possible that it can be created. 691 00:36:07,719 --> 00:36:09,960 Speaker 1: And so yeah, you can imagine there being a pre 692 00:36:10,160 --> 00:36:13,040 Speaker 1: Big Bang moment when there was a universe but just 693 00:36:13,160 --> 00:36:16,120 Speaker 1: no space. All right, Well, it sounds like both theories 694 00:36:16,320 --> 00:36:19,120 Speaker 1: are pretty cool with the idea of not having space. 695 00:36:19,320 --> 00:36:22,520 Speaker 1: They can both take it or leave it. Yeah, absolutely, 696 00:36:22,680 --> 00:36:27,000 Speaker 1: variations of quantum mechanics can accommodate space not being fundamental 697 00:36:27,239 --> 00:36:29,680 Speaker 1: even though our current quantum field theory sort of assumes 698 00:36:29,680 --> 00:36:32,319 Speaker 1: that it's there. You can build these extensions that sort 699 00:36:32,320 --> 00:36:34,840 Speaker 1: of make it possible for space to be emergent, for 700 00:36:34,880 --> 00:36:37,880 Speaker 1: it to bubble up, rather than just being an assumed 701 00:36:37,960 --> 00:36:41,080 Speaker 1: property of the universe. Alright, so space, take it or 702 00:36:41,160 --> 00:36:44,319 Speaker 1: leave it? Leave it? All right, Let's get into how 703 00:36:44,360 --> 00:36:48,879 Speaker 1: we would ever know if space is or not disposable 704 00:36:49,040 --> 00:36:51,839 Speaker 1: or dispensable. But speaking of time, it's time to take 705 00:36:51,880 --> 00:37:08,239 Speaker 1: another quick break, all right, Daniel. It sounds like physicists 706 00:37:08,239 --> 00:37:10,479 Speaker 1: could take space or leave it. It sounds like both 707 00:37:10,520 --> 00:37:14,799 Speaker 1: theories about the universe would be okay. They wouldn't break 708 00:37:14,800 --> 00:37:17,600 Speaker 1: down if you suddenly got rid of space. Yeah. And 709 00:37:17,640 --> 00:37:20,080 Speaker 1: I think if you took a survey of physicists right 710 00:37:20,120 --> 00:37:23,600 Speaker 1: now and you ask them if space was fundamental or emergent, 711 00:37:23,640 --> 00:37:26,319 Speaker 1: if it came from something else more fundamental, I bet 712 00:37:26,320 --> 00:37:29,239 Speaker 1: you get like saying that it's an emergent, that it's 713 00:37:29,360 --> 00:37:32,239 Speaker 1: not fundamental, that it's comes up from something else, which 714 00:37:32,280 --> 00:37:34,440 Speaker 1: means that you could have a universe without it, or 715 00:37:34,560 --> 00:37:37,200 Speaker 1: portions of the universe without it. I think that's the 716 00:37:37,280 --> 00:37:39,920 Speaker 1: current mainstream thinking. And as we all know, the universe 717 00:37:40,000 --> 00:37:44,160 Speaker 1: works democratically, so whatever the majority says must be true. No, 718 00:37:44,280 --> 00:37:48,040 Speaker 1: we're definitely capable of being misled and having the wrong idea. 719 00:37:48,120 --> 00:37:50,120 Speaker 1: But I think it's sort of exciting that it's widespread. 720 00:37:50,160 --> 00:37:51,759 Speaker 1: It means that lots of people are working on it, 721 00:37:51,920 --> 00:37:54,920 Speaker 1: People are developing new ways of thinking about these really 722 00:37:54,960 --> 00:37:57,960 Speaker 1: really basic questions, and people out there also should be 723 00:37:58,000 --> 00:38:00,680 Speaker 1: excited it means that, like we're just the beginning of 724 00:38:00,719 --> 00:38:04,600 Speaker 1: asking questions about the universe and tackling them. If you 725 00:38:04,640 --> 00:38:07,000 Speaker 1: are excited about questions like you know, what is the 726 00:38:07,120 --> 00:38:09,360 Speaker 1: universe and where did they come from? And what's it 727 00:38:09,480 --> 00:38:12,440 Speaker 1: really made out of? Remember that there are huge tracts 728 00:38:12,560 --> 00:38:15,719 Speaker 1: of questions that are just really being explored by This 729 00:38:15,840 --> 00:38:17,880 Speaker 1: is just now, and so there's plenty of room to 730 00:38:17,960 --> 00:38:22,279 Speaker 1: make like really fundamental Einstein level discoveries about the nature 731 00:38:22,320 --> 00:38:24,360 Speaker 1: of the universe. Right. I think what you're saying is 732 00:38:24,360 --> 00:38:27,439 Speaker 1: that there's an electoral college in the universe, and who knows, 733 00:38:27,560 --> 00:38:31,120 Speaker 1: who knows what the rules are for that? That's right. Fortunately, 734 00:38:31,160 --> 00:38:35,480 Speaker 1: physics is easier to calculate than the electoral college. All right, 735 00:38:35,520 --> 00:38:38,279 Speaker 1: I guess maybe now the big question is how would 736 00:38:38,360 --> 00:38:41,720 Speaker 1: we know or not whether space is fundamental or whether 737 00:38:41,800 --> 00:38:44,640 Speaker 1: or not it's like an add on or like an 738 00:38:44,640 --> 00:38:48,319 Speaker 1: optional preference in the universe you could live in. Is 739 00:38:48,320 --> 00:38:50,120 Speaker 1: there a way for us to test it because we 740 00:38:50,200 --> 00:38:53,279 Speaker 1: live in this space that we're trying to test. Is 741 00:38:53,320 --> 00:38:56,200 Speaker 1: it possible to I don't know, create an experiment where 742 00:38:56,200 --> 00:38:59,440 Speaker 1: you have no space? Yeah, there's really two steps to that. First, 743 00:38:59,560 --> 00:39:02,759 Speaker 1: is we gotta make more theoretical progress and then we 744 00:39:02,840 --> 00:39:06,000 Speaker 1: got to do some experiments. So on the theoretical side, 745 00:39:06,040 --> 00:39:09,960 Speaker 1: what we really need is a unification of quantum mechanics 746 00:39:09,960 --> 00:39:13,040 Speaker 1: and general relativity. We need a theory of quantum gravity 747 00:39:13,080 --> 00:39:15,960 Speaker 1: that tells us how the universe works, so that we 748 00:39:16,000 --> 00:39:19,280 Speaker 1: can think about, like what is space, and this theory 749 00:39:19,600 --> 00:39:21,880 Speaker 1: if it all hangs together and like does everything it 750 00:39:21,960 --> 00:39:25,160 Speaker 1: has to do, meaning it can describe everything that gravity 751 00:39:25,200 --> 00:39:27,799 Speaker 1: can do, and they can describe all the tiny fundamental 752 00:39:27,840 --> 00:39:30,960 Speaker 1: particles and it brings those together in a way that 753 00:39:31,080 --> 00:39:33,359 Speaker 1: makes sense that you know, they don't disagree with each 754 00:39:33,400 --> 00:39:36,239 Speaker 1: other like the current quantum mechanics and general relativity do. 755 00:39:36,719 --> 00:39:39,000 Speaker 1: Then we can ask questions of that theory. So first 756 00:39:39,000 --> 00:39:41,480 Speaker 1: we've got to make progress. Theoretically, we need like an 757 00:39:41,520 --> 00:39:44,359 Speaker 1: actual theory that totally works. Before the break, we talked 758 00:39:44,400 --> 00:39:47,480 Speaker 1: about a few possibilities like directions people are going. These 759 00:39:47,520 --> 00:39:51,000 Speaker 1: are like half formed ideas. People are like building scaffolding. 760 00:39:51,080 --> 00:39:53,120 Speaker 1: You can see the outlines of a structure of people 761 00:39:53,120 --> 00:39:55,840 Speaker 1: are trying to make work, but nobody has an actual 762 00:39:55,920 --> 00:39:59,040 Speaker 1: functioning theory of quantum gravity where we can ask these 763 00:39:59,120 --> 00:40:01,560 Speaker 1: kind of questions and get answers. I guess you need 764 00:40:01,680 --> 00:40:03,600 Speaker 1: some sort of theory first, right, Like, you can't just 765 00:40:03,680 --> 00:40:06,319 Speaker 1: take out space and measure it and not measure it. 766 00:40:06,480 --> 00:40:08,680 Speaker 1: How do you measure not space? Well, we have done 767 00:40:08,680 --> 00:40:11,560 Speaker 1: a lot of really cool experiments about space, right, Like 768 00:40:11,640 --> 00:40:15,720 Speaker 1: seeing gravitational waves is incredible. It tells us that space 769 00:40:15,840 --> 00:40:19,279 Speaker 1: really is sort of fungible and dynamic. And measuring the 770 00:40:19,280 --> 00:40:22,000 Speaker 1: expansion of the universe that's also kind of an experiment 771 00:40:22,080 --> 00:40:24,440 Speaker 1: that tells us what's going on with space. And a 772 00:40:24,440 --> 00:40:27,360 Speaker 1: lot of times experiment informs us. Remember that we didn't 773 00:40:27,360 --> 00:40:30,960 Speaker 1: expect the universe to be expanding in an accelerating manner 774 00:40:31,040 --> 00:40:33,600 Speaker 1: until we saw it, and it totally shocked us and 775 00:40:33,640 --> 00:40:36,799 Speaker 1: surprised us. So sometimes experiments can inform us. I think 776 00:40:36,800 --> 00:40:40,120 Speaker 1: in this case, we really need theory to tell us, 777 00:40:40,160 --> 00:40:42,960 Speaker 1: like how we can do experiments to answer this question, 778 00:40:43,000 --> 00:40:46,200 Speaker 1: because currently the only experiments I can think of are 779 00:40:46,280 --> 00:40:48,280 Speaker 1: ones that are like at the center of a black 780 00:40:48,320 --> 00:40:52,560 Speaker 1: hole or requires super colliders the size of a solar system, 781 00:40:52,800 --> 00:40:56,200 Speaker 1: not things we can get done tomorrow. No, exactly, because 782 00:40:56,239 --> 00:41:00,000 Speaker 1: for example, general relativity and quantum mechanics they disagree about 783 00:41:00,040 --> 00:41:01,840 Speaker 1: what's at the center of a black hole. You know, 784 00:41:01,960 --> 00:41:05,840 Speaker 1: general relativity says, oh, there's a singularity there, but quantum 785 00:41:05,840 --> 00:41:08,120 Speaker 1: mechanics says, you can't have a singularity because that's too 786 00:41:08,200 --> 00:41:11,640 Speaker 1: much information isolated in one little spot and it violates 787 00:41:11,680 --> 00:41:14,640 Speaker 1: the Heisenberg uncertainty principle. And so if you could see 788 00:41:14,680 --> 00:41:16,440 Speaker 1: what was going on inside the black hole, you can 789 00:41:16,480 --> 00:41:18,720 Speaker 1: get great clues as to how to build your theory 790 00:41:18,719 --> 00:41:22,200 Speaker 1: of quantum gravity. Or if you could somehow do tests 791 00:41:22,239 --> 00:41:26,200 Speaker 1: of particles feeling gravitational forces by building a super huge 792 00:41:26,239 --> 00:41:30,120 Speaker 1: collider and smashing those particles together at crazy high energies 793 00:41:30,360 --> 00:41:33,440 Speaker 1: enough energy where like gravity is as powerful as the 794 00:41:33,480 --> 00:41:35,560 Speaker 1: other forces, that maybe you could get a clue as 795 00:41:35,600 --> 00:41:37,640 Speaker 1: to how to build your theory of quantum gravity. But 796 00:41:37,680 --> 00:41:40,640 Speaker 1: we can't do either of those experiments today, And so 797 00:41:40,680 --> 00:41:43,080 Speaker 1: I think what we need is some inside from the 798 00:41:43,080 --> 00:41:45,800 Speaker 1: theory to tell us, well, look, here's how the universe 799 00:41:45,920 --> 00:41:48,320 Speaker 1: is put together. Here's our theory of what spaces, and 800 00:41:48,920 --> 00:41:51,359 Speaker 1: this theory gives us a clue about how to look 801 00:41:51,400 --> 00:41:53,920 Speaker 1: for evidence that the theory is correct. You know, there's 802 00:41:53,960 --> 00:41:57,160 Speaker 1: some like wrinkles, some experiment we can predict the outcome 803 00:41:57,200 --> 00:41:59,719 Speaker 1: of that can tell you whether or not this is right. 804 00:41:59,840 --> 00:42:01,640 Speaker 1: It's like if only you can break the loss of 805 00:42:01,680 --> 00:42:06,560 Speaker 1: physics so that you could figure out the laws of exactly. 806 00:42:06,800 --> 00:42:08,799 Speaker 1: And there's maybe one more hint of something that we 807 00:42:08,800 --> 00:42:11,359 Speaker 1: can do, which is that we can look for more 808 00:42:11,440 --> 00:42:14,719 Speaker 1: evidence of this creation of space. We can look for 809 00:42:14,880 --> 00:42:18,280 Speaker 1: evidence of those first moments just after the Big Bang 810 00:42:18,440 --> 00:42:22,319 Speaker 1: and trying to find some gravitational radiation from the Big 811 00:42:22,320 --> 00:42:24,759 Speaker 1: Bang itself. But what do you mean, like a shock wave, 812 00:42:24,880 --> 00:42:28,719 Speaker 1: or like actual radiation, or like gravitons. Yes, exactly all 813 00:42:28,760 --> 00:42:31,880 Speaker 1: of those things. You know that we have microwave background 814 00:42:31,960 --> 00:42:35,239 Speaker 1: radiation from about four hundred thousand years after the Big Bang, 815 00:42:35,280 --> 00:42:38,640 Speaker 1: when this hot plasma cooled and became transparent. We see 816 00:42:38,640 --> 00:42:42,120 Speaker 1: those photons, and people often say that that radiation is 817 00:42:42,200 --> 00:42:44,880 Speaker 1: like from the Big Bang itself. It's not quite as 818 00:42:44,920 --> 00:42:47,840 Speaker 1: from you know, four hundred thousand years after the Big Bang, 819 00:42:48,239 --> 00:42:51,120 Speaker 1: when the universe became transparent and that light is now 820 00:42:51,160 --> 00:42:54,160 Speaker 1: still propagating around. We'd love to see earlier. We'd have 821 00:42:54,239 --> 00:42:57,760 Speaker 1: to look further back to the actual creation of the universe, 822 00:42:57,800 --> 00:43:00,279 Speaker 1: whatever happened there, And so it might be Passe will 823 00:43:00,320 --> 00:43:03,800 Speaker 1: do that by looking for gravitational waves that were created 824 00:43:03,840 --> 00:43:07,320 Speaker 1: in those very first moments when the universe was expanding 825 00:43:07,360 --> 00:43:10,759 Speaker 1: so rapidly, we think that gravitational waves were made. So 826 00:43:10,800 --> 00:43:14,880 Speaker 1: there's another kind of radiation called the cosmic gravitational background 827 00:43:15,320 --> 00:43:17,880 Speaker 1: that might have clues as to what the nature of 828 00:43:17,920 --> 00:43:20,760 Speaker 1: spaces and whether it was created in those first moments, 829 00:43:20,800 --> 00:43:23,640 Speaker 1: if we could see it like the echoes of the 830 00:43:23,640 --> 00:43:26,600 Speaker 1: creation of space, yes, exactly, and so we have theories 831 00:43:26,600 --> 00:43:29,840 Speaker 1: about what that might look like under various configurations. And 832 00:43:29,880 --> 00:43:33,200 Speaker 1: you might remember several years ago people didn't experiment where 833 00:43:33,200 --> 00:43:36,280 Speaker 1: they thought they measured those waves. It was called BICEP two. 834 00:43:36,320 --> 00:43:38,000 Speaker 1: But then it turns out that they were mistaken and 835 00:43:38,000 --> 00:43:40,640 Speaker 1: they were actually just measuring dust between galaxies. So that 836 00:43:40,680 --> 00:43:43,600 Speaker 1: was disappointing, But it might still be possible with a 837 00:43:43,640 --> 00:43:46,680 Speaker 1: better round of experiments, more precision and control of that dust, 838 00:43:46,920 --> 00:43:49,719 Speaker 1: to see the actual radiation from the early universe and 839 00:43:49,800 --> 00:43:52,560 Speaker 1: get a glimmour as to whether space was created or 840 00:43:52,560 --> 00:43:55,960 Speaker 1: whether it had always been there. And there's another possibility 841 00:43:56,160 --> 00:43:58,640 Speaker 1: right us to whether or not we can confirm this 842 00:43:58,920 --> 00:44:02,120 Speaker 1: existence or the tendency of space, and that is that 843 00:44:02,320 --> 00:44:04,760 Speaker 1: maybe in the future there might not be any space. 844 00:44:04,920 --> 00:44:08,200 Speaker 1: Right exactly, are we going to run out of space 845 00:44:08,520 --> 00:44:12,280 Speaker 1: or are we just gonna, you know, get a victim 846 00:44:12,280 --> 00:44:14,560 Speaker 1: from our house. No, you're absolutely right. And some of 847 00:44:14,560 --> 00:44:18,680 Speaker 1: these theories of loop quantum gravity, for example, they predict 848 00:44:18,960 --> 00:44:21,719 Speaker 1: that the universe's expansion will stop and it will turn 849 00:44:21,760 --> 00:44:25,040 Speaker 1: around and it will compactify, so that space is like 850 00:44:25,120 --> 00:44:28,160 Speaker 1: being destroyed instead of being created, and we'll have like 851 00:44:28,200 --> 00:44:31,440 Speaker 1: a reverse big bang, this big crunch, And it's not 852 00:44:31,480 --> 00:44:33,560 Speaker 1: clear what would happen after that. Would we get another 853 00:44:33,600 --> 00:44:36,200 Speaker 1: big bang? Would we just have no space for a while? 854 00:44:36,280 --> 00:44:39,120 Speaker 1: But does time even exist anymore? We don't know. So yeah, 855 00:44:39,239 --> 00:44:41,640 Speaker 1: stick around another few trillion years and the question might 856 00:44:41,680 --> 00:44:44,239 Speaker 1: just answer itself. Yeah, things might get a little bit 857 00:44:44,280 --> 00:44:48,120 Speaker 1: more crowded or were space and cluttered? All right? Well, 858 00:44:48,200 --> 00:44:50,680 Speaker 1: it sounds like it is possible for the universe to 859 00:44:50,800 --> 00:44:53,120 Speaker 1: not have any space, But we may not find out 860 00:44:53,120 --> 00:44:56,560 Speaker 1: any time, you know, unless we observe something incredible or 861 00:44:56,680 --> 00:44:58,840 Speaker 1: we make a breakthrough in one of these theories that 862 00:44:59,000 --> 00:45:01,959 Speaker 1: let us look or you know, kinks that we can 863 00:45:02,160 --> 00:45:05,120 Speaker 1: use this evidence that space cannot exist. Yes, and I 864 00:45:05,160 --> 00:45:07,560 Speaker 1: think that there will be theoretical progress. People are working 865 00:45:07,600 --> 00:45:10,239 Speaker 1: really hard on this stuff. Black hole information paradox is 866 00:45:10,280 --> 00:45:12,600 Speaker 1: giving us some clues. So there's a lot of really 867 00:45:12,680 --> 00:45:15,319 Speaker 1: smart people working really hard on these questions, and I 868 00:45:15,360 --> 00:45:17,239 Speaker 1: think in the next five or ten years we'll see 869 00:45:17,239 --> 00:45:21,400 Speaker 1: some really clever, fascinating, mind blowing theories coming out to 870 00:45:21,480 --> 00:45:24,360 Speaker 1: explain our bunkers universe. They just need a little space, 871 00:45:25,160 --> 00:45:28,880 Speaker 1: you know, no pressure. All right, Well, we hope you 872 00:45:28,960 --> 00:45:33,080 Speaker 1: enjoyed that discussion. Thanks for joining us, see you next time. 873 00:45:40,800 --> 00:45:43,600 Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain 874 00:45:43,680 --> 00:45:46,640 Speaker 1: the Universe is a production of I Heart Radio or 875 00:45:46,719 --> 00:45:49,640 Speaker 1: more podcast from my heart Radio visit the I heart 876 00:45:49,719 --> 00:45:53,319 Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your 877 00:45:53,360 --> 00:46:04,319 Speaker 1: favorite shows.