1 00:00:07,880 --> 00:00:11,119 Speaker 1: Physicists talk a lot about what happened in the first 2 00:00:11,400 --> 00:00:16,480 Speaker 1: moments of the universe. Non physicists sometimes ask, why do 3 00:00:16,560 --> 00:00:20,919 Speaker 1: you all care so much? Why should anyone care this question? 4 00:00:21,360 --> 00:00:25,160 Speaker 1: Flabber gasks me, of course we should care. Who wouldn't 5 00:00:25,239 --> 00:00:30,320 Speaker 1: want to know? It's the literal cosmological context of our lives. 6 00:00:31,200 --> 00:00:33,680 Speaker 1: Knowing what happened in the early universe would be a 7 00:00:33,800 --> 00:00:36,960 Speaker 1: huge clue in all sorts of late night dorm room 8 00:00:37,040 --> 00:00:40,640 Speaker 1: conversations about why are we here? And it could inform 9 00:00:40,760 --> 00:00:43,640 Speaker 1: you know how we should live our lives. How is 10 00:00:43,680 --> 00:00:47,120 Speaker 1: it possible, I wonder for people to walk around not 11 00:00:47,360 --> 00:00:51,080 Speaker 1: caring about the early universe, not wanting to know about 12 00:00:51,080 --> 00:00:54,280 Speaker 1: the origin of the cosmos. If you were expecting me 13 00:00:54,360 --> 00:00:57,520 Speaker 1: at this point to drop some personal growth story where 14 00:00:57,560 --> 00:01:00,080 Speaker 1: I came to realize that not everyone cares about the 15 00:01:00,200 --> 00:01:04,440 Speaker 1: things I'm going to disappoint you. I'm still totally flabbergasted 16 00:01:04,720 --> 00:01:08,760 Speaker 1: if people aren't interested in the early universe, because we 17 00:01:08,920 --> 00:01:12,040 Speaker 1: think there are so many answers to the big questions 18 00:01:12,319 --> 00:01:16,000 Speaker 1: waiting for us there. When the universe was hot and dense, 19 00:01:16,080 --> 00:01:19,760 Speaker 1: it behaved differently. The forces were unified and things were 20 00:01:19,800 --> 00:01:24,840 Speaker 1: harmonious described by a grand unified theory, which we hope 21 00:01:24,880 --> 00:01:30,240 Speaker 1: has mathematical beauty enough to transcend its unfortunate acronym gut. 22 00:01:30,800 --> 00:01:34,240 Speaker 1: As the universe cooled, these symmetries cracked and broke into 23 00:01:34,240 --> 00:01:38,080 Speaker 1: the laws that we have today. On today's episode, we're 24 00:01:38,080 --> 00:01:40,920 Speaker 1: going to be digging into those first few moments, explaining 25 00:01:41,160 --> 00:01:44,800 Speaker 1: how forces can be unified and what it means for 26 00:01:44,880 --> 00:01:49,640 Speaker 1: them to break apart. We'll take a journey through time, space, energy, 27 00:01:50,080 --> 00:01:56,320 Speaker 1: and ugly acronyms. Welcome to Daniel and Kelly's Extraordinary acronymical Universe. 28 00:02:09,440 --> 00:02:09,760 Speaker 2: Hello. 29 00:02:09,800 --> 00:02:13,240 Speaker 3: I'm Kelly Widersmith. I study parasites and space, and gut 30 00:02:13,320 --> 00:02:15,760 Speaker 3: is an acronym in animal behavior as well, but for 31 00:02:15,840 --> 00:02:17,480 Speaker 3: us it means giving up time. 32 00:02:20,720 --> 00:02:20,919 Speaker 2: Hi. 33 00:02:21,040 --> 00:02:24,280 Speaker 1: I'm Daniel. I'm a particle physicist who also likes thinking 34 00:02:24,400 --> 00:02:27,800 Speaker 1: about aliens, and I'm in a hot competition to be 35 00:02:27,960 --> 00:02:31,600 Speaker 1: vice provost for GUT research at the Whitsun Institute. 36 00:02:31,919 --> 00:02:34,480 Speaker 3: Oh, but that means something totally that's not an acronym 37 00:02:34,520 --> 00:02:37,320 Speaker 3: at all, though, Right, that's just straight up guts. No 38 00:02:37,320 --> 00:02:40,600 Speaker 3: one's giving up over there, there's no depressing, giving up. 39 00:02:40,720 --> 00:02:45,360 Speaker 1: No Katrina studies literal actual guts, and I study hypothetical 40 00:02:45,400 --> 00:02:48,640 Speaker 1: potential Grand unified theories, and I feel like, you know, 41 00:02:48,880 --> 00:02:51,280 Speaker 1: maybe that's more important. I don't know. We argue about it. 42 00:02:51,320 --> 00:02:53,280 Speaker 3: Now you're wrong. You're wrong. Giving up time has to 43 00:02:53,280 --> 00:02:55,600 Speaker 3: do with eating though. It's about like, how long do 44 00:02:55,639 --> 00:02:58,320 Speaker 3: you forage in a certain patch before you decide that 45 00:02:58,440 --> 00:03:00,520 Speaker 3: your payoff would be higher if you went to go 46 00:03:00,919 --> 00:03:03,640 Speaker 3: forge in a different patch? Oh wow, because you know 47 00:03:03,960 --> 00:03:05,520 Speaker 3: the cost of being in that patch and the amount 48 00:03:05,560 --> 00:03:08,720 Speaker 3: of food available, et cetera. It's actually very mathy. A 49 00:03:08,720 --> 00:03:11,040 Speaker 3: lot of math goes into figuring out giving up time. 50 00:03:11,320 --> 00:03:14,880 Speaker 1: But anyway, well, maybe the Grand Unified theory all along 51 00:03:15,040 --> 00:03:17,200 Speaker 1: was how we're going to unify all of our science 52 00:03:17,240 --> 00:03:21,840 Speaker 1: into one acronym. Whoa, yeah, I guess the meta acronym. 53 00:03:21,919 --> 00:03:25,320 Speaker 3: Yeah, yeah, I feel like it should be something funny. 54 00:03:25,800 --> 00:03:26,880 Speaker 3: Maybe gut is not going. 55 00:03:26,800 --> 00:03:27,080 Speaker 1: To be it. 56 00:03:27,120 --> 00:03:29,280 Speaker 3: But here's my question for you. So, say we're talking 57 00:03:29,320 --> 00:03:32,079 Speaker 3: a lot about the Big Bang or the BB. 58 00:03:34,160 --> 00:03:37,080 Speaker 1: The BB. No, that's terrible. 59 00:03:37,840 --> 00:03:41,000 Speaker 3: Your outline says BB throughout. And so I assumed that 60 00:03:41,120 --> 00:03:44,360 Speaker 3: was like a field. Is that just a Daniel laziness thing? 61 00:03:44,560 --> 00:03:48,160 Speaker 1: Nobody ever pronounces that acronym the BB. Nobody refers to 62 00:03:48,160 --> 00:03:52,080 Speaker 1: the Big Thing as the BB, although maybe now they will. 63 00:03:52,120 --> 00:03:54,320 Speaker 1: And though I've written that many many times, I've never 64 00:03:54,400 --> 00:03:57,360 Speaker 1: even mentally thought of it out loud as like the BB. 65 00:03:58,360 --> 00:04:01,160 Speaker 3: All right, well, I am a real trendsetter, and so 66 00:04:01,400 --> 00:04:03,520 Speaker 3: I suspect from now on when you go to conferences, 67 00:04:03,560 --> 00:04:07,440 Speaker 3: it's gonna be the BB, no said quickly, just like that. 68 00:04:08,680 --> 00:04:11,160 Speaker 3: But so here's my question for you. So, you know, 69 00:04:11,200 --> 00:04:14,400 Speaker 3: we talk regularly about how we know what it was 70 00:04:14,520 --> 00:04:17,039 Speaker 3: like like at the moment of the Big Bang and 71 00:04:17,080 --> 00:04:19,560 Speaker 3: then moving forward, But we can't know what it was 72 00:04:19,640 --> 00:04:22,359 Speaker 3: like before the Big Bang because we can only see 73 00:04:22,480 --> 00:04:25,839 Speaker 3: what happened at the Big Bang and then afterwards. But 74 00:04:26,200 --> 00:04:28,840 Speaker 3: what do you think it was like before the Big Bang? 75 00:04:28,839 --> 00:04:31,440 Speaker 3: Because surely you have like smoked some banana peels and 76 00:04:31,440 --> 00:04:34,240 Speaker 3: thought about that, and so what like if you had 77 00:04:34,279 --> 00:04:37,000 Speaker 3: to guess, what would you guess? What is your like 78 00:04:37,200 --> 00:04:40,080 Speaker 3: sleepy time dreaming? What is what was it like before 79 00:04:40,080 --> 00:04:40,400 Speaker 3: the BB? 80 00:04:41,160 --> 00:04:45,480 Speaker 1: Yeah, great question, the pre BB. Yeah, that's a good question. 81 00:04:45,600 --> 00:04:47,839 Speaker 1: You know, I really don't know, but I do have 82 00:04:48,000 --> 00:04:51,840 Speaker 1: a mental image for placeholders. Okay, Like if I don't know, 83 00:04:52,120 --> 00:04:55,680 Speaker 1: my brain conjures up this like black and gray fuzz 84 00:04:55,680 --> 00:04:59,159 Speaker 1: where you can just make out the outlines of huge 85 00:04:59,200 --> 00:05:02,839 Speaker 1: purple dragon really, which in my mind represent like the 86 00:05:03,200 --> 00:05:08,000 Speaker 1: crazy unknown thing we might discover. Who knows, Like, you know, 87 00:05:08,040 --> 00:05:09,880 Speaker 1: when we turn on the large hay drunk collider, who 88 00:05:09,920 --> 00:05:12,919 Speaker 1: knows what's gonna come out? Maybe huge purple dragons. And 89 00:05:12,960 --> 00:05:15,800 Speaker 1: obviously I don't expect literal purple dragons, which just sort 90 00:05:15,800 --> 00:05:18,240 Speaker 1: of like a stand in, and then my mind just 91 00:05:18,279 --> 00:05:21,440 Speaker 1: sort of goes there visually. Also, so if I rewind 92 00:05:21,640 --> 00:05:25,640 Speaker 1: past The Big Bang, I literally imagine a dark cosmos 93 00:05:25,760 --> 00:05:26,920 Speaker 1: with purple dragons in it. 94 00:05:27,080 --> 00:05:27,599 Speaker 2: I love that. 95 00:05:28,080 --> 00:05:29,680 Speaker 3: Does that have anything to do with like I think 96 00:05:29,720 --> 00:05:32,120 Speaker 3: in maps, when we didn't know what there was, we 97 00:05:32,240 --> 00:05:33,880 Speaker 3: used to write here there be dragons. 98 00:05:34,200 --> 00:05:34,960 Speaker 1: Oh was that? 99 00:05:35,160 --> 00:05:36,719 Speaker 3: No, that's not where that came from. 100 00:05:36,720 --> 00:05:38,920 Speaker 1: Though if I was smarter and more literate, then I 101 00:05:38,960 --> 00:05:42,279 Speaker 1: would claim that that was inspired by there be dragons. Yes, 102 00:05:42,680 --> 00:05:44,240 Speaker 1: would make me sound a lot smarter. 103 00:05:44,760 --> 00:05:46,719 Speaker 3: Well, I could be totally wrong about that. Maybe that 104 00:05:46,800 --> 00:05:49,640 Speaker 3: might be some like intranet lore that I picked up somewhere, 105 00:05:49,680 --> 00:05:52,520 Speaker 3: but I liked it so it stuck and Okay that's 106 00:05:52,600 --> 00:05:53,080 Speaker 3: very cool. 107 00:05:53,680 --> 00:05:55,800 Speaker 1: Yeah, Well there you go a little insight into Daniel's 108 00:05:55,839 --> 00:05:56,720 Speaker 1: banana peel brain. 109 00:05:56,960 --> 00:05:59,839 Speaker 3: Yeah, I don't have a brain that makes pictures quite 110 00:06:00,080 --> 00:06:02,400 Speaker 3: hm as much as yours does, I think. 111 00:06:02,600 --> 00:06:06,560 Speaker 1: All right, So then in Kelly's brain, what's the Prebb 112 00:06:07,000 --> 00:06:07,400 Speaker 1: look like? 113 00:06:07,720 --> 00:06:10,200 Speaker 3: I do? I haven't really thought about what the prebbe. 114 00:06:10,240 --> 00:06:12,800 Speaker 3: I mean, I don't have as much like information to 115 00:06:14,200 --> 00:06:16,000 Speaker 3: But I guess you would say that you also don't 116 00:06:16,000 --> 00:06:18,920 Speaker 3: have information to inform what the Prebb was like. So 117 00:06:18,960 --> 00:06:21,120 Speaker 3: none of us do, and so I don't know. Maybe 118 00:06:21,160 --> 00:06:23,200 Speaker 3: just pure darkness. 119 00:06:23,480 --> 00:06:23,720 Speaker 2: Hmm. 120 00:06:24,400 --> 00:06:26,800 Speaker 1: Interesting, that's like the default state of the universe. 121 00:06:26,960 --> 00:06:29,840 Speaker 3: Yeah, I don't know. I like the idea of dragons. 122 00:06:30,880 --> 00:06:32,640 Speaker 1: Well, let's dig into the episode and maybe at the 123 00:06:32,720 --> 00:06:34,359 Speaker 1: end of it we can check in with Kelly to 124 00:06:34,360 --> 00:06:38,200 Speaker 1: see if it's changed her mental picture of the Prebb. Okay, 125 00:06:38,279 --> 00:06:40,960 Speaker 1: but today's episode is actually inspired by a listener who 126 00:06:41,000 --> 00:06:44,080 Speaker 1: watched a YouTube video about the early Universe and the 127 00:06:44,120 --> 00:06:48,000 Speaker 1: grain unified Force and how it broke into four other forces, 128 00:06:48,279 --> 00:06:51,960 Speaker 1: didn't really understand it and wanted more details. Here's a 129 00:06:52,080 --> 00:06:55,560 Speaker 1: question I got from de Layer Mustafa from New South Wales. 130 00:06:55,800 --> 00:06:59,520 Speaker 2: Hi, Danielle and Kelly. My understanding is that after the 131 00:06:59,560 --> 00:07:04,040 Speaker 2: big bad. There was one grand unified force and then 132 00:07:04,160 --> 00:07:08,200 Speaker 2: this force started breaking down to the four forces which 133 00:07:08,200 --> 00:07:12,320 Speaker 2: we know now. My question is what was there when 134 00:07:12,400 --> 00:07:16,160 Speaker 2: this force was around in terms of energy and particles, 135 00:07:16,280 --> 00:07:18,200 Speaker 2: like what was the form of energy? Was it in 136 00:07:18,280 --> 00:07:22,480 Speaker 2: form of photon or whatever type of energy? And also 137 00:07:22,600 --> 00:07:28,000 Speaker 2: what particles bosone or fermion and so on, and what 138 00:07:28,440 --> 00:07:32,360 Speaker 2: caused this force to break down? And if you can explain, 139 00:07:32,720 --> 00:07:35,880 Speaker 2: what were the steps of this breakdown, what happened first 140 00:07:35,880 --> 00:07:41,080 Speaker 2: and so on, and which particles or energies resulted from 141 00:07:41,160 --> 00:07:47,120 Speaker 2: these transitions steps, and also what forces and particles and 142 00:07:47,320 --> 00:07:50,680 Speaker 2: energy we have today. Thank you very much, Daniel and Kelly. 143 00:07:51,400 --> 00:07:53,080 Speaker 3: There's a lot of questions in that question. 144 00:07:54,680 --> 00:07:57,000 Speaker 1: There are, and this happens a lot that people watch 145 00:07:57,000 --> 00:08:01,320 Speaker 1: a video or listen to some other podcast and they 146 00:08:01,320 --> 00:08:03,000 Speaker 1: don't quite get it, and they write to us and 147 00:08:03,000 --> 00:08:05,840 Speaker 1: they're like, what does this mean? And I'm not mad 148 00:08:05,880 --> 00:08:08,800 Speaker 1: about that at all. I'm very glad that people are 149 00:08:09,040 --> 00:08:12,080 Speaker 1: watching videos and listening to a science podcasts. I'm also 150 00:08:12,080 --> 00:08:13,960 Speaker 1: glad that they reach out when they don't get it, 151 00:08:14,440 --> 00:08:16,160 Speaker 1: that they come to us, because it means that they 152 00:08:16,240 --> 00:08:17,640 Speaker 1: think will answer, because we do. 153 00:08:17,800 --> 00:08:20,240 Speaker 3: Yes and that's an honor I think to be the 154 00:08:20,280 --> 00:08:22,360 Speaker 3: person that people go to when they're like, oh, I 155 00:08:22,440 --> 00:08:25,560 Speaker 3: was still confused. Can you break this down? Even more so, 156 00:08:25,640 --> 00:08:27,880 Speaker 3: thank you for trusting us with your questions. 157 00:08:28,120 --> 00:08:30,240 Speaker 1: And this is a super fun topic and what I 158 00:08:30,280 --> 00:08:32,680 Speaker 1: really did want to dig into because it's an opportunity 159 00:08:32,720 --> 00:08:35,280 Speaker 1: to clear up I think a lot of misconceptions about 160 00:08:35,280 --> 00:08:38,480 Speaker 1: what it means to unify forces and how things break 161 00:08:38,480 --> 00:08:40,839 Speaker 1: in the universe and how the universe has changed over 162 00:08:40,920 --> 00:08:43,840 Speaker 1: time and what that really means, and dig into the 163 00:08:43,840 --> 00:08:46,760 Speaker 1: sort of philosophical underpinnings of effective theories which I always 164 00:08:46,800 --> 00:08:49,600 Speaker 1: want to talk about. But before we get there, and 165 00:08:49,640 --> 00:08:52,400 Speaker 1: before Kelly has to rein me in, I checked in 166 00:08:52,440 --> 00:08:55,360 Speaker 1: with the Extraordinaries to hear what they thought about this topic. 167 00:08:55,800 --> 00:08:59,679 Speaker 1: I asked our cadre of volunteers, what broke the Grand 168 00:08:59,800 --> 00:09:04,680 Speaker 1: un Force in the early Universe. If you enjoy hearing 169 00:09:04,679 --> 00:09:06,840 Speaker 1: this segment and want to add your voice to it, 170 00:09:06,880 --> 00:09:09,400 Speaker 1: please don't be shy. We would welcome you in this chorus. 171 00:09:09,400 --> 00:09:13,720 Speaker 1: Write to us two questions at Danielankelly dot org. Here's 172 00:09:13,760 --> 00:09:16,760 Speaker 1: what listeners had to say about what broke the Grand 173 00:09:16,840 --> 00:09:19,040 Speaker 1: Unified Force in the early universe. 174 00:09:19,400 --> 00:09:20,920 Speaker 2: Which force are we talking about again? 175 00:09:21,360 --> 00:09:22,400 Speaker 3: The ark energy? 176 00:09:22,760 --> 00:09:26,240 Speaker 2: I think the overall energy drops below a certain threshold 177 00:09:26,320 --> 00:09:28,320 Speaker 2: and that's what broke it. I would say that the 178 00:09:28,360 --> 00:09:31,480 Speaker 2: grand unified force broke itself in the same way then 179 00:09:31,480 --> 00:09:33,840 Speaker 2: egg breaks when the chicken cracks out of it. 180 00:09:33,960 --> 00:09:37,199 Speaker 1: Something to do with the balance between matter and anti matter. 181 00:09:37,679 --> 00:09:43,040 Speaker 1: As this is Daniel Kelly's extraordinarily fecal at times universe. 182 00:09:43,360 --> 00:09:45,600 Speaker 1: It might be pooh, did a cat knock it off 183 00:09:45,600 --> 00:09:49,360 Speaker 1: the shelf? I think the emergence of light Chuck Norris 184 00:09:49,920 --> 00:09:53,400 Speaker 1: expanded no more unified force? Does it have anything to 185 00:09:53,440 --> 00:09:54,880 Speaker 1: do with Plank's constant. 186 00:09:55,080 --> 00:09:57,920 Speaker 2: We don't have a grand unified theory yet. 187 00:09:58,080 --> 00:10:02,440 Speaker 3: Some kind of symmetry violation that only manifests below a 188 00:10:02,480 --> 00:10:07,679 Speaker 3: certain energy threshold. It wasn't me, honest, oh man, Chuck 189 00:10:07,720 --> 00:10:10,120 Speaker 3: Norris rest in peace. I gotta be honest. I don't 190 00:10:10,160 --> 00:10:13,320 Speaker 3: know anything about Chuck Norris the man, but I knew 191 00:10:13,360 --> 00:10:16,280 Speaker 3: a lot about Chuck Norris the myth. I really loved 192 00:10:16,280 --> 00:10:19,360 Speaker 3: those Chuck Norris jokes at some point in my life. 193 00:10:19,800 --> 00:10:22,240 Speaker 3: And Chuck Norris is no more. 194 00:10:24,080 --> 00:10:25,480 Speaker 1: He lives on forever in you. 195 00:10:25,640 --> 00:10:28,240 Speaker 3: Kelly, Ah, okay, that. 196 00:10:28,280 --> 00:10:30,520 Speaker 1: Makes you uncomfortable. 197 00:10:31,720 --> 00:10:33,480 Speaker 3: If that's the case, I probably should learn a little 198 00:10:33,480 --> 00:10:35,480 Speaker 3: bit more about the man. But I enjoyed the. 199 00:10:35,480 --> 00:10:39,520 Speaker 1: Jokes or maybe some martial arts. Yeah, but we're not 200 00:10:39,600 --> 00:10:43,160 Speaker 1: talking about Chuck Norris. Mostly today we're talking about the universe, 201 00:10:43,480 --> 00:10:46,280 Speaker 1: and we're talking about how the universe changes over time. 202 00:10:47,000 --> 00:10:49,360 Speaker 1: And before we dig into what are the fundamental forces 203 00:10:49,400 --> 00:10:52,280 Speaker 1: and how do they unify high energy and then walking 204 00:10:52,320 --> 00:10:55,199 Speaker 1: through the timeline of the very early universe to explain 205 00:10:55,240 --> 00:10:56,960 Speaker 1: all of that, I want to spend a minute on 206 00:10:56,960 --> 00:11:00,160 Speaker 1: the big picture of what it means to how the 207 00:11:00,240 --> 00:11:03,040 Speaker 1: laws of physics change, because that's what we're talking about. 208 00:11:03,040 --> 00:11:06,920 Speaker 1: The grand unified force broke into other forces, and what 209 00:11:06,960 --> 00:11:08,680 Speaker 1: does it mean to have one set of forces and 210 00:11:08,679 --> 00:11:10,880 Speaker 1: then later another set of forces. How does the universe 211 00:11:11,000 --> 00:11:13,240 Speaker 1: change its forces? Is that going to happen in the 212 00:11:13,280 --> 00:11:15,920 Speaker 1: future of what's going on here? And so I want 213 00:11:15,920 --> 00:11:19,440 Speaker 1: to remind everybody that there might be some fundamental theory 214 00:11:19,520 --> 00:11:22,760 Speaker 1: of the universe that describes everything that's happening and controls 215 00:11:22,800 --> 00:11:25,880 Speaker 1: everything that's happening. We don't know what that is. We 216 00:11:25,960 --> 00:11:28,679 Speaker 1: don't have it right. It's not something we possess now. 217 00:11:28,679 --> 00:11:31,360 Speaker 1: We can't write it down. And even if we did, 218 00:11:31,480 --> 00:11:34,559 Speaker 1: even if like advanced aliens showed up and they told 219 00:11:34,640 --> 00:11:38,160 Speaker 1: us here's the equation of the universe, it might not 220 00:11:38,280 --> 00:11:42,319 Speaker 1: be very useful. Right the way, like even particle physics today, 221 00:11:42,480 --> 00:11:45,280 Speaker 1: which describes a lot of the quantum mechanical details of 222 00:11:45,320 --> 00:11:48,640 Speaker 1: our universe, is not all that useful. You don't use 223 00:11:48,679 --> 00:11:51,600 Speaker 1: it to predict how a ball flies across your backyard, 224 00:11:51,800 --> 00:11:55,120 Speaker 1: or whether Tesla stock is going to go up or down, 225 00:11:55,280 --> 00:11:57,319 Speaker 1: or whether this hurricane is going to be your left 226 00:11:57,400 --> 00:12:00,000 Speaker 1: or right. It's not very useful because it's very dis 227 00:12:00,080 --> 00:12:03,160 Speaker 1: connected from those level of details you need to simulate 228 00:12:03,240 --> 00:12:06,480 Speaker 1: like ten to the thirty seven electrons to predict what's 229 00:12:06,520 --> 00:12:08,800 Speaker 1: going to happen in that hurricane. It's it's not a 230 00:12:08,920 --> 00:12:11,160 Speaker 1: useful theory. So number one, we don't have it, and 231 00:12:11,280 --> 00:12:13,439 Speaker 1: number two, even if we had it, it wouldn't be the 232 00:12:13,480 --> 00:12:16,600 Speaker 1: kind of thing we needed to describe the universe we experience. 233 00:12:16,880 --> 00:12:17,679 Speaker 1: Does that make sense? 234 00:12:18,040 --> 00:12:21,320 Speaker 3: It does? So this sort of sounded familiar, and so 235 00:12:21,520 --> 00:12:24,240 Speaker 3: is this what we were talking about with Ethan Siegel 236 00:12:24,600 --> 00:12:27,720 Speaker 3: when we were talking about single unified theories in physics 237 00:12:27,800 --> 00:12:30,320 Speaker 3: when we had them on the show on October fifteenth, 238 00:12:30,360 --> 00:12:31,160 Speaker 3: twenty twenty five. 239 00:12:31,440 --> 00:12:33,520 Speaker 1: Oh my gosh, what a photographic memory. 240 00:12:33,240 --> 00:12:34,400 Speaker 3: No, no, no, no, looked it up. 241 00:12:34,440 --> 00:12:38,280 Speaker 1: Looked it up, it looked it up in advance. Even 242 00:12:38,320 --> 00:12:41,240 Speaker 1: look at that doing your homework. Yes, exactly. We were 243 00:12:41,240 --> 00:12:43,920 Speaker 1: talking about whether there is an underlying theory or not. 244 00:12:44,679 --> 00:12:47,000 Speaker 1: Because we don't have that theory. What we do have 245 00:12:47,320 --> 00:12:50,360 Speaker 1: are what we call effective theories that are useful in 246 00:12:50,440 --> 00:12:53,920 Speaker 1: various situations. So we don't think and don't pretend our 247 00:12:53,960 --> 00:12:57,439 Speaker 1: fundamental theories of the universe. There are approximate theories that 248 00:12:57,520 --> 00:13:00,360 Speaker 1: help us out in certain situations. The way, for sample, 249 00:13:00,600 --> 00:13:03,840 Speaker 1: Newton's laws can predict what happens when you throw a 250 00:13:03,840 --> 00:13:07,600 Speaker 1: ball across your backyard. Nobody thinks Newton's laws are written 251 00:13:07,600 --> 00:13:11,120 Speaker 1: in the cosmos right, that they're fundamental in some way. 252 00:13:11,440 --> 00:13:14,920 Speaker 1: But they work. They're effective. They're an approximate description of 253 00:13:14,960 --> 00:13:18,000 Speaker 1: physics at this scale, and they work. But they work 254 00:13:18,040 --> 00:13:20,800 Speaker 1: within boundaries. If your ball goes near the speed of light, 255 00:13:20,840 --> 00:13:23,160 Speaker 1: it doesn't really work anymore. If your ball goes near 256 00:13:23,160 --> 00:13:25,760 Speaker 1: a black hole, it doesn't really work anymore. And so 257 00:13:25,960 --> 00:13:29,079 Speaker 1: rather than having a deep fundamental theory that isn't useful 258 00:13:29,120 --> 00:13:32,160 Speaker 1: for anything, we have a patchwork of effective theories that 259 00:13:32,160 --> 00:13:35,560 Speaker 1: are each useful for something. And I think maybe an 260 00:13:35,600 --> 00:13:37,640 Speaker 1: illustrated way to think about this is to think about 261 00:13:37,640 --> 00:13:40,920 Speaker 1: the phases of water. Like, we have a theory that 262 00:13:40,960 --> 00:13:43,959 Speaker 1: describes how water behaves when it's a vapor, the ideal 263 00:13:44,000 --> 00:13:47,480 Speaker 1: gas law. We have a different theory that describes how 264 00:13:47,520 --> 00:13:51,000 Speaker 1: water behaves when it's a fluid, right, fluid dynamics. Very 265 00:13:51,000 --> 00:13:54,280 Speaker 1: different set of equations, right, they both describe water. It's 266 00:13:54,280 --> 00:13:58,040 Speaker 1: the same stuff, right, Probably in the core of the 267 00:13:58,120 --> 00:14:01,080 Speaker 1: universe there are fundamental laws that are determining what's happening 268 00:14:01,080 --> 00:14:04,360 Speaker 1: to water molecules in both scenarios. But when you zoom out, 269 00:14:04,480 --> 00:14:07,559 Speaker 1: you end up with very different effective laws, and if 270 00:14:07,559 --> 00:14:09,600 Speaker 1: you freeze it, you get an even different set of 271 00:14:09,600 --> 00:14:13,400 Speaker 1: effective laws. Right, So what's happening there? The universe is 272 00:14:13,440 --> 00:14:17,800 Speaker 1: not changing the rules. We are changing how we describe 273 00:14:17,960 --> 00:14:21,080 Speaker 1: the universe because we want a useful theory, and the 274 00:14:21,200 --> 00:14:24,720 Speaker 1: useful theory is different in each situation, frozen water, liquid water, 275 00:14:24,960 --> 00:14:25,800 Speaker 1: gaseous water. 276 00:14:26,440 --> 00:14:30,040 Speaker 3: Does this reflect that we are missing something? And if 277 00:14:30,040 --> 00:14:33,840 Speaker 3: we were like smarter, we could have an equation that 278 00:14:33,880 --> 00:14:37,280 Speaker 3: would describe what's happening in all of those situations or 279 00:14:37,400 --> 00:14:40,560 Speaker 3: is this just the nature of the universe there are 280 00:14:40,600 --> 00:14:44,680 Speaker 3: like discontinuities and you need different equations to describe things 281 00:14:44,720 --> 00:14:47,760 Speaker 3: at different times, or yeah, what do you think is 282 00:14:47,760 --> 00:14:48,320 Speaker 3: going on there? 283 00:14:48,680 --> 00:14:50,840 Speaker 1: Yeah, we don't know, right, We don't know if there 284 00:14:50,840 --> 00:14:54,200 Speaker 1: really is a deep truth. It could be that all 285 00:14:54,240 --> 00:14:58,560 Speaker 1: there is are these effective theories, these approximate patchworks that 286 00:14:58,720 --> 00:15:01,440 Speaker 1: maybe come together, or so maybe there are gaps between them. 287 00:15:01,680 --> 00:15:04,600 Speaker 1: We don't know. If in Siegel believes strongly that there 288 00:15:04,760 --> 00:15:07,880 Speaker 1: is a fundamental theory and that all of these effective 289 00:15:07,880 --> 00:15:10,800 Speaker 1: theories are just approximate versions of it, and he might 290 00:15:10,800 --> 00:15:13,720 Speaker 1: be right, but we don't know. And even if we did, 291 00:15:13,800 --> 00:15:16,200 Speaker 1: we probably wouldn't use it right because it wouldn't be 292 00:15:16,280 --> 00:15:18,480 Speaker 1: very useful. Like if I could tell you that the 293 00:15:18,560 --> 00:15:21,920 Speaker 1: universe is made out of Squigglyon's right, now, doesn't mean 294 00:15:21,960 --> 00:15:25,120 Speaker 1: I could calculate the flow of sewage through pipes using 295 00:15:25,160 --> 00:15:28,200 Speaker 1: squiggly on physics, right, because it would take like an 296 00:15:28,280 --> 00:15:31,080 Speaker 1: enormous number of calculations and be dependent on all these details. 297 00:15:31,280 --> 00:15:34,880 Speaker 1: I would probably still use Bernoulli's equation or whatever fluid 298 00:15:34,960 --> 00:15:38,600 Speaker 1: dynamics people use, right, because that's effective. That's very useful. 299 00:15:39,040 --> 00:15:42,040 Speaker 1: So these effective theories are very powerful, and as the 300 00:15:42,120 --> 00:15:46,200 Speaker 1: situation changes, as the phase changes in water, you change 301 00:15:46,240 --> 00:15:49,240 Speaker 1: your effective theory. And this is I think it really 302 00:15:49,240 --> 00:15:51,920 Speaker 1: helps you understand what's going on in physics. A lot 303 00:15:51,960 --> 00:15:54,840 Speaker 1: of the time that we summarize a lot of the 304 00:15:54,880 --> 00:15:58,080 Speaker 1: microscopic details we don't know, often in terms of one 305 00:15:58,280 --> 00:16:02,120 Speaker 1: like unexplained number. Give you another example. We often talk 306 00:16:02,280 --> 00:16:06,280 Speaker 1: about light flowing through a material and moving it slower 307 00:16:06,320 --> 00:16:08,840 Speaker 1: than the speed of light. Right, people say, light moves 308 00:16:08,880 --> 00:16:10,840 Speaker 1: through a vacuum of the speed of light, but through 309 00:16:10,880 --> 00:16:14,160 Speaker 1: glass it's a little bit slower, and through other materials 310 00:16:14,160 --> 00:16:16,360 Speaker 1: it's at a different speed. And there's a number of 311 00:16:16,360 --> 00:16:19,840 Speaker 1: the index of refraction that tells you how light bends 312 00:16:19,840 --> 00:16:22,480 Speaker 1: at also the speed of light through that material. And 313 00:16:22,520 --> 00:16:24,320 Speaker 1: that's confusing to people because they're like, how do you 314 00:16:24,320 --> 00:16:27,120 Speaker 1: slow down a photon? What's going on? And that's an 315 00:16:27,160 --> 00:16:31,000 Speaker 1: example of an effective theory. It's not that photons are 316 00:16:31,040 --> 00:16:34,520 Speaker 1: slowing down and moving its slower than the speed of light. Instead, 317 00:16:34,560 --> 00:16:37,600 Speaker 1: it's as if light was moving slower. It's not that 318 00:16:37,600 --> 00:16:39,880 Speaker 1: that's what's happening. But if you describe it that way, 319 00:16:40,160 --> 00:16:43,280 Speaker 1: all the predictions come out. So if you really want 320 00:16:43,320 --> 00:16:45,680 Speaker 1: to zoom in on the microscopic details, you see light 321 00:16:45,800 --> 00:16:48,160 Speaker 1: never moves that's slower than the speed of light. It 322 00:16:48,320 --> 00:16:50,800 Speaker 1: like zaps between atom and atom, and there's an excited 323 00:16:50,880 --> 00:16:53,240 Speaker 1: wave of electrons that move through the material. It's very, 324 00:16:53,320 --> 00:16:57,000 Speaker 1: very complicated. The microphysics of light moving through material super 325 00:16:57,080 --> 00:16:59,840 Speaker 1: duper complicated. If you don't know how that works, or 326 00:16:59,840 --> 00:17:02,320 Speaker 1: you don't care, you can just zoom out and say, 327 00:17:02,600 --> 00:17:04,920 Speaker 1: it's kind of like light moves a little bit slower 328 00:17:04,960 --> 00:17:07,480 Speaker 1: than the speed of light, and all the numbers work out. 329 00:17:07,800 --> 00:17:11,320 Speaker 1: All those microphysics get wrapped up in this one number. 330 00:17:11,359 --> 00:17:14,440 Speaker 1: You can measure the index of refraction. It's the same 331 00:17:14,480 --> 00:17:17,840 Speaker 1: thing for like friction. Friction is super duper complicated. You 332 00:17:17,840 --> 00:17:20,800 Speaker 1: have two surfaces, they're sliding over each other. How they 333 00:17:20,840 --> 00:17:24,040 Speaker 1: interact depends on lots of details. You can sum it 334 00:17:24,080 --> 00:17:26,199 Speaker 1: all up in one number. It's called the coefficient of 335 00:17:26,240 --> 00:17:29,320 Speaker 1: friction point seven or point four to two or whatever 336 00:17:29,640 --> 00:17:32,199 Speaker 1: tells you how two things slide across each other. If 337 00:17:32,240 --> 00:17:35,160 Speaker 1: you don't know or care about the microphysics. So often 338 00:17:35,160 --> 00:17:37,480 Speaker 1: we have these effective theories where a lot of the 339 00:17:37,560 --> 00:17:40,760 Speaker 1: high end details are bundled up into a single number. 340 00:17:40,800 --> 00:17:43,520 Speaker 1: We just measure that encapsulates all those details we either 341 00:17:43,560 --> 00:17:46,400 Speaker 1: don't know or don't care about. So as we move 342 00:17:46,480 --> 00:17:48,679 Speaker 1: through the timeline of the universe and we talk about 343 00:17:48,840 --> 00:17:51,200 Speaker 1: we're using this theory, or now we have two forces, 344 00:17:51,240 --> 00:17:54,000 Speaker 1: now we have four forces, what was changing was not 345 00:17:54,040 --> 00:17:57,720 Speaker 1: how the universe works. There's still that fundamental law perhaps 346 00:17:57,720 --> 00:18:01,360 Speaker 1: that Ethan Siegel believes in. What is changing is how 347 00:18:01,440 --> 00:18:04,800 Speaker 1: we effectively describe the universe because the phase of the 348 00:18:04,920 --> 00:18:08,359 Speaker 1: universe changes. The universe goes from very hot to very cold, 349 00:18:08,720 --> 00:18:11,840 Speaker 1: and as it goes through those temperature changes, the effective 350 00:18:11,960 --> 00:18:17,040 Speaker 1: laws change. What's useful, what's practical for describing the universe changes. 351 00:18:17,640 --> 00:18:19,520 Speaker 3: I'm going to go ahead and admit that I was 352 00:18:20,000 --> 00:18:23,400 Speaker 3: moderately quiet during the conversation that you and Ethan had 353 00:18:23,440 --> 00:18:26,200 Speaker 3: because I was, you know, not I didn't have much 354 00:18:26,200 --> 00:18:28,520 Speaker 3: to add, let's say, but I thought that I remembered 355 00:18:28,560 --> 00:18:33,720 Speaker 3: Ethan arguing that there was like a unified thing that 356 00:18:33,800 --> 00:18:37,679 Speaker 3: was happening at the early universe, but then something about 357 00:18:37,800 --> 00:18:41,200 Speaker 3: like the energy state went down over time, and then 358 00:18:41,359 --> 00:18:45,280 Speaker 3: the unified thing broke down as the energy changed phase 359 00:18:45,400 --> 00:18:48,639 Speaker 3: or there was less of it, And so what was 360 00:18:48,680 --> 00:18:52,520 Speaker 3: he saying, and how does it differ from what you believe? 361 00:18:52,520 --> 00:18:55,040 Speaker 3: Because I remembered you two didn't quite agree on something. 362 00:18:57,200 --> 00:19:00,000 Speaker 1: Yeah, good memory. There's something else really cool that happened. 363 00:19:00,080 --> 00:19:03,520 Speaker 1: And as you increase the temperature of the universe, you 364 00:19:03,600 --> 00:19:06,960 Speaker 1: go to hotter and hotter phases of the universe. Then 365 00:19:07,000 --> 00:19:11,040 Speaker 1: the differences between the various effective theories tend to sort 366 00:19:11,080 --> 00:19:13,520 Speaker 1: of wash out, that become irrelevant, sort of like you 367 00:19:13,560 --> 00:19:15,560 Speaker 1: know the way the shape of a mountain matters a 368 00:19:15,560 --> 00:19:17,719 Speaker 1: lot if you're climbing over it, but if you're flying 369 00:19:17,760 --> 00:19:20,520 Speaker 1: over it, it doesn't really matter so much. And so 370 00:19:20,680 --> 00:19:23,360 Speaker 1: we'll go into detail about exactly that. But I think 371 00:19:23,359 --> 00:19:25,280 Speaker 1: Ethan and I had a different concept of what it 372 00:19:25,320 --> 00:19:28,560 Speaker 1: meant to unify physics. He was thinking about the very 373 00:19:28,600 --> 00:19:31,760 Speaker 1: early universe, when things are very hot, can you ignore 374 00:19:31,800 --> 00:19:35,720 Speaker 1: the details between all the forces in your effective theory? 375 00:19:36,240 --> 00:19:38,800 Speaker 1: And I was thinking about whether there's an underlying theory 376 00:19:38,880 --> 00:19:42,720 Speaker 1: even now that does unify everything, but maybe isn't a 377 00:19:42,800 --> 00:19:43,879 Speaker 1: useful effective theory? 378 00:19:44,280 --> 00:19:47,240 Speaker 3: Got it all right, Let's take a break, and when 379 00:19:47,280 --> 00:19:50,720 Speaker 3: we get back, let's remind ourselves what the five forces 380 00:19:50,760 --> 00:20:14,240 Speaker 3: are today and talk about how we might unify them. 381 00:20:14,320 --> 00:20:17,400 Speaker 3: All right, we're back and Daniel, it's physics one oh one. 382 00:20:18,040 --> 00:20:21,080 Speaker 3: What are the five forces that we recognize today? 383 00:20:21,520 --> 00:20:23,399 Speaker 1: All right, this is a lot of fun, and already 384 00:20:23,400 --> 00:20:26,520 Speaker 1: people will disagree because some people say there aren't five forces, 385 00:20:26,560 --> 00:20:29,320 Speaker 1: there are four forces that have three forces. Whatever. Let's 386 00:20:29,359 --> 00:20:34,600 Speaker 1: start with the broadest categorization and say electricity, right, that's 387 00:20:34,640 --> 00:20:38,280 Speaker 1: the thing that power is your laptop. And then magnetism, 388 00:20:38,480 --> 00:20:42,200 Speaker 1: which will count separately and then unify later. A magnetism, 389 00:20:42,200 --> 00:20:45,560 Speaker 1: of course, is you know, refrigerator magnets and loadstones and 390 00:20:45,600 --> 00:20:50,879 Speaker 1: compasses and stuff like that. Then there's the weak nuclear force, right, 391 00:20:50,960 --> 00:20:54,280 Speaker 1: which is responsible for like radioactive decay. It doesn't play 392 00:20:54,280 --> 00:20:57,119 Speaker 1: a big role in our lives, but it's there and important. 393 00:20:57,720 --> 00:21:01,639 Speaker 1: Then there's this strong nuclear force that's very important for 394 00:21:01,760 --> 00:21:04,640 Speaker 1: fusion and holding the nucleus together. So those are the 395 00:21:04,680 --> 00:21:09,800 Speaker 1: four quantum fundamental forces. And then there's gravity, which seems 396 00:21:09,840 --> 00:21:11,840 Speaker 1: like a force to us and I think deserves to 397 00:21:11,840 --> 00:21:14,760 Speaker 1: be included on this list because we hope to unify 398 00:21:14,800 --> 00:21:18,520 Speaker 1: it with these four eventually. But that's the starting point 399 00:21:18,600 --> 00:21:22,000 Speaker 1: sort of. Historically, humans have been poking around and noticing 400 00:21:22,040 --> 00:21:26,239 Speaker 1: stuff happening, and we built up this sort of phenomenological history, like, 401 00:21:26,800 --> 00:21:28,720 Speaker 1: we see this kind of stuff, let's call it one thing. 402 00:21:28,760 --> 00:21:30,680 Speaker 1: We see that kind of stuff, let's call it one thing. 403 00:21:30,920 --> 00:21:34,960 Speaker 1: We started out with basically five fundamental forces, and so 404 00:21:35,160 --> 00:21:37,800 Speaker 1: first we can talk about how we unify them as 405 00:21:37,800 --> 00:21:40,080 Speaker 1: we go backwards in time, and then in the next segment, 406 00:21:40,160 --> 00:21:42,600 Speaker 1: let's walk through the history of the early universe and 407 00:21:42,600 --> 00:21:44,920 Speaker 1: see them breaking as time goes forwards. 408 00:21:45,280 --> 00:21:47,720 Speaker 3: Okay, real quick, before we do that, do we think 409 00:21:47,760 --> 00:21:50,760 Speaker 3: that we've got all of the forces that matter or 410 00:21:50,800 --> 00:21:56,960 Speaker 3: because we don't understand dark matter or is it dark energy? 411 00:21:56,960 --> 00:21:58,160 Speaker 3: Which one do we not understand? 412 00:21:58,240 --> 00:21:59,800 Speaker 1: Both neither need to understand. 413 00:22:00,440 --> 00:22:02,719 Speaker 3: Okay, are there Is it possible if there's more forces 414 00:22:02,760 --> 00:22:04,960 Speaker 3: we're gonna have to unify once we understand things better. 415 00:22:05,000 --> 00:22:06,920 Speaker 3: And these are just the five we're working with right now. 416 00:22:07,359 --> 00:22:09,919 Speaker 1: Oh yes, and I hope so Okay, there could definitely 417 00:22:10,000 --> 00:22:12,520 Speaker 1: be more forces involved in the dark sector. If there 418 00:22:12,520 --> 00:22:14,800 Speaker 1: are lots of dark particles out there, they could interact 419 00:22:14,840 --> 00:22:18,040 Speaker 1: with each other using new dark forces. There could be 420 00:22:18,480 --> 00:22:21,080 Speaker 1: dark photons and dark w's and dark z's and all 421 00:22:21,119 --> 00:22:22,920 Speaker 1: sorts of stuff. There could be a dark strong force, 422 00:22:23,520 --> 00:22:26,119 Speaker 1: and dark energy could be the product of another force. 423 00:22:26,200 --> 00:22:28,400 Speaker 1: We don't know about it either. It's really a big 424 00:22:28,480 --> 00:22:33,440 Speaker 1: question mark. It's basically flying purple dragons where physics is concerned. So, yes, 425 00:22:33,480 --> 00:22:35,160 Speaker 1: these are the ones we know today. Good point. 426 00:22:35,440 --> 00:22:37,720 Speaker 3: And I love the idea of a dark sector. I 427 00:22:37,760 --> 00:22:40,440 Speaker 3: feel like that needs to be in someone's books somewhere. 428 00:22:40,480 --> 00:22:42,640 Speaker 3: But okay, so how do we unify them? 429 00:22:43,000 --> 00:22:46,400 Speaker 1: Yeah? So what we do is we notice that forces 430 00:22:46,440 --> 00:22:49,560 Speaker 1: have things in common, right, but that doesn't mean they 431 00:22:49,560 --> 00:22:52,000 Speaker 1: have to be the same. When we unify forces, we 432 00:22:52,040 --> 00:22:56,199 Speaker 1: don't say electricity and magnetism are the same thing. What 433 00:22:56,280 --> 00:22:58,720 Speaker 1: we do is we notice that there are two sides 434 00:22:58,760 --> 00:23:02,399 Speaker 1: of a coherent hole that they make more sense to 435 00:23:02,480 --> 00:23:06,119 Speaker 1: click together than to keep track of them separately. Like 436 00:23:06,160 --> 00:23:09,240 Speaker 1: if you have literally two sides of a coin and 437 00:23:09,320 --> 00:23:12,159 Speaker 1: you never noticed that heads and tails are related to 438 00:23:12,200 --> 00:23:14,359 Speaker 1: each other, and you kept track of like heads and 439 00:23:14,400 --> 00:23:17,520 Speaker 1: tails separately, and somebody told you, oh, did you realize 440 00:23:17,520 --> 00:23:20,000 Speaker 1: that heads and tails are literally two sides of the 441 00:23:20,040 --> 00:23:23,160 Speaker 1: same coin. That's where the expression comes from. Right, It's 442 00:23:23,240 --> 00:23:25,960 Speaker 1: much simpler because then you notice patterns like you can 443 00:23:26,000 --> 00:23:28,119 Speaker 1: only see heads or tails. You can't see them at 444 00:23:28,119 --> 00:23:31,040 Speaker 1: the same time. Right, there's a relationship between them. If 445 00:23:31,040 --> 00:23:33,280 Speaker 1: you add up the number of heads and tails, you 446 00:23:33,320 --> 00:23:35,880 Speaker 1: get the number of flips you made for example. Right. 447 00:23:36,280 --> 00:23:38,879 Speaker 1: So that doesn't require heads and tails to be the 448 00:23:38,920 --> 00:23:42,000 Speaker 1: same thing. It requires them to be two parts of 449 00:23:42,040 --> 00:23:45,719 Speaker 1: a larger hole. It's the same with like elephants. If 450 00:23:45,760 --> 00:23:48,679 Speaker 1: you study elephant trunks and you study elphint tails and 451 00:23:48,760 --> 00:23:51,359 Speaker 1: you don't think about the relationship between them, you're missing 452 00:23:51,359 --> 00:23:54,120 Speaker 1: out in the bigger picture, and your theory of elephant 453 00:23:54,160 --> 00:23:57,000 Speaker 1: tails and trunks is not nearly as good as a 454 00:23:57,200 --> 00:24:01,680 Speaker 1: unified theory of elephants that includes tails and trunks. Right. So, again, 455 00:24:02,080 --> 00:24:04,640 Speaker 1: that's not saying tales and trunks are the same. It's 456 00:24:04,640 --> 00:24:07,200 Speaker 1: saying that they're part of a larger hole. Got it. 457 00:24:07,280 --> 00:24:08,960 Speaker 3: Yeah, you don't want to miss the whole elephant because 458 00:24:08,960 --> 00:24:09,639 Speaker 3: it could squish you. 459 00:24:12,320 --> 00:24:14,439 Speaker 1: That's right. And we made a lot of progress early 460 00:24:14,480 --> 00:24:19,639 Speaker 1: on in finding connections between the electricity and magnetism. With Maxwell. 461 00:24:20,119 --> 00:24:23,440 Speaker 1: There were these different observations of electricity and magnetism, and 462 00:24:23,480 --> 00:24:25,840 Speaker 1: people had the various laws about it, Gauss's law and 463 00:24:25,960 --> 00:24:30,560 Speaker 1: Peer's law, etc. And Maxwell put together the four laws 464 00:24:30,880 --> 00:24:33,600 Speaker 1: that related these things, and he saw a bunch of 465 00:24:33,640 --> 00:24:37,000 Speaker 1: symmetries here, and he noted that the equations were very 466 00:24:37,040 --> 00:24:41,240 Speaker 1: similar from the magnetic and electrical points of view. Basically, 467 00:24:41,320 --> 00:24:44,920 Speaker 1: you could swap the electric fields and the magnetic fields 468 00:24:44,920 --> 00:24:47,879 Speaker 1: in the equations and they wouldn't change. There was a 469 00:24:47,920 --> 00:24:50,399 Speaker 1: symmetry there right, that they were playing like the same 470 00:24:50,560 --> 00:24:55,280 Speaker 1: role asterisk right almost. He actually noticed that there was 471 00:24:55,320 --> 00:25:00,040 Speaker 1: a gap. That symmetry almost worked, and he wanted it to. 472 00:25:00,280 --> 00:25:02,119 Speaker 1: He's like, oh, this would be so much prettier if 473 00:25:02,160 --> 00:25:05,720 Speaker 1: it did work. So he penciled in the missing term 474 00:25:05,840 --> 00:25:09,200 Speaker 1: that would be needed to provide this symmetry. There was 475 00:25:09,240 --> 00:25:12,159 Speaker 1: no evidence for this term in the universe yet. He 476 00:25:12,280 --> 00:25:15,880 Speaker 1: just said, hmm, boy, this would be more symmetric if 477 00:25:15,920 --> 00:25:17,480 Speaker 1: it was there, And then he went out and looked 478 00:25:17,480 --> 00:25:20,840 Speaker 1: for it and founded that's displacement current. And so that 479 00:25:20,960 --> 00:25:23,359 Speaker 1: shows you, like, wow, there really is some symmetry in 480 00:25:23,359 --> 00:25:26,600 Speaker 1: the universe. You know, following mathematical symmetries leads you to 481 00:25:26,600 --> 00:25:30,600 Speaker 1: physical discoveries. I love that. And so we know now 482 00:25:30,640 --> 00:25:34,080 Speaker 1: that electricity and magnetism have a very close relationship. You know, 483 00:25:34,560 --> 00:25:37,880 Speaker 1: if you have electric charges and they move, that gives 484 00:25:37,920 --> 00:25:40,919 Speaker 1: you magnetic fields, or if you have magnetic fields that 485 00:25:41,080 --> 00:25:44,480 Speaker 1: change that can generate electric fields, so the two are 486 00:25:44,640 --> 00:25:46,879 Speaker 1: very closely coupled. One can make the other. 487 00:25:46,800 --> 00:25:53,919 Speaker 3: One okay, But sometimes the universe has mathematical symmetry and 488 00:25:54,040 --> 00:25:58,040 Speaker 3: other times it doesn't. Yes, so it's nice that it's here. 489 00:25:59,160 --> 00:26:02,120 Speaker 3: But then we find that, like water, needs different equations 490 00:26:02,119 --> 00:26:05,360 Speaker 3: for different phases, and that doesn't feel very satisfactory. And 491 00:26:05,440 --> 00:26:08,760 Speaker 3: so I guess I'd like a whole episode on when 492 00:26:08,760 --> 00:26:11,080 Speaker 3: you should expect the world to be beautiful and symmetrical 493 00:26:11,119 --> 00:26:13,000 Speaker 3: and when you shouldn't. And I'm guessing the answer is 494 00:26:13,080 --> 00:26:13,520 Speaker 3: we don't know. 495 00:26:13,920 --> 00:26:17,359 Speaker 1: Yeah. Well, even within electricity magnetism, the universe seems to 496 00:26:17,359 --> 00:26:21,520 Speaker 1: reject perfect symmetries because you can't actually just swap electric 497 00:26:21,520 --> 00:26:24,720 Speaker 1: fields and magnetic fields in Maxwell's equations because they have 498 00:26:24,720 --> 00:26:27,439 Speaker 1: a really big difference. And that is that we have 499 00:26:27,600 --> 00:26:32,160 Speaker 1: sources of electric fields, like particles with charges are sources 500 00:26:32,160 --> 00:26:35,600 Speaker 1: of electric fields. Right. An electron just sitting there makes 501 00:26:35,600 --> 00:26:39,840 Speaker 1: an electric field, but there is no such source of 502 00:26:39,880 --> 00:26:45,439 Speaker 1: a magnetic field. Magnetic fields only come from charges in motion. 503 00:26:46,200 --> 00:26:50,520 Speaker 1: There's no like equivalent of the electron, no magnetron, or 504 00:26:50,560 --> 00:26:54,399 Speaker 1: we call it in particlehysics a magnetic monopole. So one 505 00:26:54,440 --> 00:26:56,919 Speaker 1: of Maxwell's equations has a zero in it to reflect 506 00:26:56,960 --> 00:26:59,720 Speaker 1: the fact that there are no sources of magnetic fields, 507 00:27:00,040 --> 00:27:02,680 Speaker 1: and another one has a non zero to count the 508 00:27:02,760 --> 00:27:05,800 Speaker 1: number of electric charges. So there is a fundamental difference 509 00:27:05,840 --> 00:27:08,600 Speaker 1: there between electricity and magnetism. So they don't have to 510 00:27:08,600 --> 00:27:11,480 Speaker 1: be identical. They just have to play nicely together. 511 00:27:11,920 --> 00:27:14,480 Speaker 3: Okay, so they're linked, but they're not like a gradient 512 00:27:14,840 --> 00:27:15,760 Speaker 3: from one to the other. 513 00:27:16,160 --> 00:27:19,679 Speaker 1: That's right exactly, though there is some evidence that the 514 00:27:19,720 --> 00:27:22,399 Speaker 1: dotted line we draw between them is a little bit 515 00:27:22,520 --> 00:27:26,760 Speaker 1: arbitrary because, for example, in a given situation, whether or 516 00:27:26,800 --> 00:27:29,800 Speaker 1: not there is a magnetic field depends on who's looking 517 00:27:29,840 --> 00:27:32,600 Speaker 1: at it. Like if you have an electron and you're 518 00:27:32,600 --> 00:27:35,440 Speaker 1: holding it in your hand, it makes an electric field, 519 00:27:35,440 --> 00:27:38,680 Speaker 1: but no magnetic field. If I'm driving by in the 520 00:27:38,720 --> 00:27:40,959 Speaker 1: highway at one hundred miles an hour, I look at 521 00:27:40,960 --> 00:27:43,640 Speaker 1: that electron, I see that as a charge in motion 522 00:27:43,920 --> 00:27:46,800 Speaker 1: because it has a velocity relative to me. Charges in 523 00:27:46,840 --> 00:27:50,760 Speaker 1: motion make magnetic fields. So my compass would measure a 524 00:27:50,800 --> 00:27:54,119 Speaker 1: magnetic field from your electron. Your compass would measure no 525 00:27:54,200 --> 00:27:58,000 Speaker 1: magnetic field. Is the magnetic field there or not. It's 526 00:27:58,080 --> 00:28:01,960 Speaker 1: frame dependent, it's observer. So where you draw that dotted 527 00:28:02,000 --> 00:28:05,640 Speaker 1: line depends on the observer, which is a strong argument 528 00:28:06,000 --> 00:28:09,600 Speaker 1: that it doesn't make sense to account for these things separately. Right, 529 00:28:09,720 --> 00:28:10,919 Speaker 1: These things really are. 530 00:28:10,880 --> 00:28:15,200 Speaker 3: Deeply linked, and that is why you say that they're linked. 531 00:28:15,200 --> 00:28:17,360 Speaker 3: But you said there's five charges, and you gave them 532 00:28:17,480 --> 00:28:21,000 Speaker 3: separate counts because they're linked, but they're different. 533 00:28:21,400 --> 00:28:24,040 Speaker 1: They are different, and historically they were separate, and then 534 00:28:24,040 --> 00:28:26,800 Speaker 1: we brought them together. And there's a really powerful lesson 535 00:28:26,880 --> 00:28:29,879 Speaker 1: in how we brought them together. Because another factor in 536 00:28:30,160 --> 00:28:34,040 Speaker 1: electricity and magnetism is the strength of the force. Like 537 00:28:34,119 --> 00:28:36,800 Speaker 1: if you're just sitting around at low speeds, electricity is 538 00:28:36,880 --> 00:28:40,720 Speaker 1: much more powerful than magnetism. There's a law, the Lorentz 539 00:28:40,760 --> 00:28:43,560 Speaker 1: force law, that tells you the force on a particle 540 00:28:43,880 --> 00:28:46,960 Speaker 1: based on the electric field and the magnetic field and 541 00:28:47,080 --> 00:28:50,520 Speaker 1: the magnetic fields. Another factor in it, it's velocity. Right, 542 00:28:50,560 --> 00:28:54,440 Speaker 1: If there's no velocity, there's no force from a magnetic field. 543 00:28:54,720 --> 00:28:56,680 Speaker 3: Okay, yeah, all right, that makes sense because you said 544 00:28:56,680 --> 00:29:00,240 Speaker 3: if you've got to be moving in that prior example, But. 545 00:29:00,240 --> 00:29:02,560 Speaker 1: What happens if you're moving at the speed of light. 546 00:29:02,920 --> 00:29:04,920 Speaker 1: If you're moving at the speed of light, that velocity 547 00:29:05,000 --> 00:29:07,720 Speaker 1: term we write the speed of light as speed equals one, 548 00:29:08,160 --> 00:29:11,120 Speaker 1: and so now the two things are totally equal. So 549 00:29:11,240 --> 00:29:14,520 Speaker 1: magnetic fields are much weaker at low speeds, but at 550 00:29:14,560 --> 00:29:18,600 Speaker 1: high speeds they become just as powerful as electric fields. 551 00:29:19,000 --> 00:29:22,320 Speaker 1: So at very high speeds, very high temperatures, if you 552 00:29:22,360 --> 00:29:24,760 Speaker 1: have a gas of particles whose particles are moving near 553 00:29:24,800 --> 00:29:27,400 Speaker 1: the speed of light, the magnetic fields are equally as 554 00:29:27,440 --> 00:29:30,200 Speaker 1: powerful as the electric fields. This is the kind of 555 00:29:30,240 --> 00:29:34,680 Speaker 1: thing we mean by unification at high energies. At high energies, 556 00:29:34,680 --> 00:29:38,240 Speaker 1: the differences between electric and magnetic fields start to wash out, 557 00:29:38,240 --> 00:29:40,520 Speaker 1: they become less important. 558 00:29:40,000 --> 00:29:42,160 Speaker 3: Are we going to find that at all of our 559 00:29:42,200 --> 00:29:44,760 Speaker 3: forces at high energy they become the same. 560 00:29:45,200 --> 00:29:47,600 Speaker 1: That's the trend. It's very tantalizing. It's the kind of 561 00:29:47,600 --> 00:29:50,520 Speaker 1: thing that make particle physicists feel like it's possible to 562 00:29:50,680 --> 00:29:54,160 Speaker 1: unify all the forces. Definitely happens here, and it happens 563 00:29:54,400 --> 00:29:57,240 Speaker 1: every time we unify a force. We find that it 564 00:29:57,320 --> 00:29:58,720 Speaker 1: happens at higher energies. 565 00:29:59,000 --> 00:30:00,960 Speaker 3: Okay, well, then let's jump to the weak and the 566 00:30:00,960 --> 00:30:01,600 Speaker 3: strong force. 567 00:30:01,640 --> 00:30:06,160 Speaker 1: Then exactly so we have electromagnetism. It's unified, and the 568 00:30:06,200 --> 00:30:09,720 Speaker 1: particle that mediate's electromagnetism is the photon, right, there's a 569 00:30:09,720 --> 00:30:15,000 Speaker 1: photon field the electromagnetic field, right, And we did that 570 00:30:15,040 --> 00:30:18,520 Speaker 1: by putting electricity and magnetism into a single framework. Well, 571 00:30:18,560 --> 00:30:20,960 Speaker 1: it turns out you can do the same with electromagnetism 572 00:30:21,280 --> 00:30:24,080 Speaker 1: and the weak force. You can put those into a 573 00:30:24,160 --> 00:30:27,200 Speaker 1: larger mathematical framework that in the same way makes a 574 00:30:27,240 --> 00:30:30,720 Speaker 1: lot more sense to keep track of and to think about, 575 00:30:30,880 --> 00:30:35,280 Speaker 1: like rotations and velocity dependence. It all works really really 576 00:30:35,320 --> 00:30:39,160 Speaker 1: well and explains a lot, but again it doesn't work perfectly. 577 00:30:39,280 --> 00:30:43,200 Speaker 1: There are still differences between electromagnetism and the weak force, 578 00:30:43,440 --> 00:30:45,520 Speaker 1: and the most important one being the weak force is 579 00:30:45,560 --> 00:30:49,000 Speaker 1: really weak. It's a weak because the particles that carry it, 580 00:30:49,320 --> 00:30:52,680 Speaker 1: the W and the Z, are really really massive, like 581 00:30:52,720 --> 00:30:55,760 Speaker 1: the W and Z way eighty and ninety times the 582 00:30:55,800 --> 00:30:59,160 Speaker 1: mass of a proton, whereas the photon is mass lists 583 00:31:00,040 --> 00:31:03,160 Speaker 1: photon can fly forever through the universe, whereas then W 584 00:31:03,320 --> 00:31:05,840 Speaker 1: and the Z are very short range because of their mass. 585 00:31:05,920 --> 00:31:08,240 Speaker 1: So it's a very weak force. So this is a 586 00:31:08,240 --> 00:31:12,000 Speaker 1: symmetry between electromagnetism and the weak force, but it's a broken. 587 00:31:11,600 --> 00:31:14,280 Speaker 3: Symmetry, all right, So what do we do to the 588 00:31:14,320 --> 00:31:16,600 Speaker 3: weak force to make the mass not matter. 589 00:31:17,240 --> 00:31:20,800 Speaker 1: We crank up the energy because the mass of the 590 00:31:20,880 --> 00:31:23,520 Speaker 1: W and Z only matter if you don't have a 591 00:31:23,520 --> 00:31:26,560 Speaker 1: lot of energy around. If everything has a huge amount 592 00:31:26,600 --> 00:31:28,240 Speaker 1: of energy, the fact that one of them has some 593 00:31:28,360 --> 00:31:31,800 Speaker 1: mass doesn't matter anymore. At the speed of light, the 594 00:31:31,840 --> 00:31:34,880 Speaker 1: mass of these particles doesn't matter. So if you crank 595 00:31:34,960 --> 00:31:38,280 Speaker 1: up the energy, then the weak force becomes stronger. It 596 00:31:38,320 --> 00:31:42,400 Speaker 1: becomes just as strong as electricity and as magnetism, and 597 00:31:42,440 --> 00:31:46,480 Speaker 1: those three strands all unifying to one beautiful theory called 598 00:31:46,520 --> 00:31:52,120 Speaker 1: the electro weak theory, which unifies electricity and magnetism us 599 00:31:52,200 --> 00:31:55,400 Speaker 1: this group theory, which French mathematical nerds invented one hundred 600 00:31:55,480 --> 00:31:58,080 Speaker 1: years earlier just because they were having fun with numbers, 601 00:31:58,440 --> 00:32:00,600 Speaker 1: and turned out to be Yeah, turned out to be 602 00:32:00,920 --> 00:32:04,920 Speaker 1: foundational in building our modern understanding of the universe. Another 603 00:32:05,000 --> 00:32:08,640 Speaker 1: reason why you should give nerds money and leave them alone. 604 00:32:08,920 --> 00:32:09,240 Speaker 3: Amen. 605 00:32:09,560 --> 00:32:11,400 Speaker 1: And this all works really well, but you know, one 606 00:32:11,440 --> 00:32:15,320 Speaker 1: obstacle is like, well, why is the weak force different 607 00:32:15,840 --> 00:32:19,280 Speaker 1: than the other forces? And that's the Higgs boson. Peter 608 00:32:19,360 --> 00:32:22,560 Speaker 1: Higgs was like, how can you put these things together 609 00:32:22,840 --> 00:32:25,720 Speaker 1: but also break that symmetry. You got to build the 610 00:32:25,760 --> 00:32:28,440 Speaker 1: symmetry and then break it. So the Higgs boson is 611 00:32:28,440 --> 00:32:31,520 Speaker 1: a thing that breaks the symmetry. It interacts with the 612 00:32:31,680 --> 00:32:34,280 Speaker 1: W and the Z bosons and gives them mass, but 613 00:32:34,480 --> 00:32:37,400 Speaker 1: doesn't interact with the photon and so leaves it massless. 614 00:32:38,000 --> 00:32:41,040 Speaker 1: So not only can we unify electricity and magnetism into 615 00:32:41,080 --> 00:32:44,120 Speaker 1: one force that's beautiful and wonderful, and high energies they 616 00:32:44,160 --> 00:32:47,800 Speaker 1: all act the same, we can also explain how at 617 00:32:47,920 --> 00:32:49,800 Speaker 1: low energies they are different. 618 00:32:50,640 --> 00:32:52,480 Speaker 3: And the reason you have to be able to do 619 00:32:52,800 --> 00:32:56,520 Speaker 3: both of these things is because we're pretty convinced at 620 00:32:56,520 --> 00:32:59,600 Speaker 3: the Big Bang all of the forces were the same, 621 00:33:00,040 --> 00:33:02,880 Speaker 3: and we know that now there are situations where they're 622 00:33:03,400 --> 00:33:05,720 Speaker 3: clearly doing different things, and so we need to be 623 00:33:05,760 --> 00:33:08,880 Speaker 3: able to explain how both of those things can happen. 624 00:33:09,440 --> 00:33:09,840 Speaker 3: Is that right? 625 00:33:09,960 --> 00:33:12,480 Speaker 1: A plus Kelly, that's right. We live in a cold 626 00:33:12,680 --> 00:33:15,880 Speaker 1: universe where things don't have the energy to fly near 627 00:33:15,920 --> 00:33:18,240 Speaker 1: the speed of light, and so these differences matter. The 628 00:33:18,240 --> 00:33:22,120 Speaker 1: weak force is measurably weaker than electricity and magnetism today 629 00:33:22,280 --> 00:33:25,280 Speaker 1: right now, but we do think in the early universe 630 00:33:25,640 --> 00:33:27,640 Speaker 1: it had more energy and it was able to ignore 631 00:33:27,960 --> 00:33:31,200 Speaker 1: essentially the Higgs field. It didn't really matter, because yeah, 632 00:33:31,240 --> 00:33:33,000 Speaker 1: you get a little bit of mass, but who cares. 633 00:33:33,520 --> 00:33:36,480 Speaker 1: You know, it's like giving a speeding ticket to a billionaire, right, 634 00:33:37,360 --> 00:33:38,760 Speaker 1: billionaires blow them down. 635 00:33:40,480 --> 00:33:43,480 Speaker 3: They're always going too fast, all right, So. 636 00:33:43,520 --> 00:33:46,480 Speaker 1: Things are going great, right. We were using group theory 637 00:33:46,520 --> 00:33:49,200 Speaker 1: and mathematics to unify these things. As we crank up 638 00:33:49,200 --> 00:33:53,080 Speaker 1: the temperature, things seem to unify beautifully. It's amazing. So 639 00:33:53,160 --> 00:33:56,280 Speaker 1: let's get to the strong force, and here we're stuck. 640 00:33:57,120 --> 00:34:01,800 Speaker 1: We would love to unify the strong into some grand 641 00:34:02,040 --> 00:34:04,959 Speaker 1: unified theory of physics that brings together all of our 642 00:34:05,040 --> 00:34:08,040 Speaker 1: quantum theories, but nobody's been able to make it work 643 00:34:08,120 --> 00:34:12,240 Speaker 1: so far. This is a target of physicists for decades 644 00:34:12,239 --> 00:34:15,000 Speaker 1: and decades, even putting aside gravity, right, we haven't even 645 00:34:15,000 --> 00:34:18,160 Speaker 1: gotten to gravity yet. We don't know how to unify 646 00:34:18,239 --> 00:34:21,080 Speaker 1: the strong force with the electro weak force. So we 647 00:34:21,160 --> 00:34:24,440 Speaker 1: really only have two quantum forces at this point, electroweek 648 00:34:24,840 --> 00:34:27,439 Speaker 1: and the strong force, and we would love to stick 649 00:34:27,480 --> 00:34:27,960 Speaker 1: them together. 650 00:34:28,440 --> 00:34:31,080 Speaker 3: And I don't want to make light of the suffering 651 00:34:31,120 --> 00:34:34,319 Speaker 3: of physicists, but I'm just going to note that electroweek 652 00:34:34,400 --> 00:34:38,240 Speaker 3: appears to be abbreviated as OW and grand unified theory 653 00:34:38,280 --> 00:34:41,879 Speaker 3: appears to be abbreviated as GUT, and so your notes say, 654 00:34:42,080 --> 00:34:46,879 Speaker 3: we cannot yet unify U into GUT. And so that's 655 00:34:46,920 --> 00:34:48,960 Speaker 3: the kind of problem you guys are working on right now. 656 00:34:49,200 --> 00:34:51,440 Speaker 1: Maybe somebody needs to come up with like a blah 657 00:34:51,520 --> 00:34:53,600 Speaker 1: theory or like a vomit. 658 00:34:53,280 --> 00:34:57,440 Speaker 3: Theory or something, and then the dragons can get cleared away. 659 00:34:58,160 --> 00:35:01,719 Speaker 1: The theory of dragon vomit's going to bring us. And 660 00:35:01,760 --> 00:35:04,680 Speaker 1: so there are obstacles here, And one obstacle is that 661 00:35:04,760 --> 00:35:08,279 Speaker 1: what happens when you turn up the energy, then the 662 00:35:08,280 --> 00:35:11,000 Speaker 1: strength of these forces changes. So all these forces have 663 00:35:11,040 --> 00:35:15,320 Speaker 1: a strength that depends on the energy. And with electricity 664 00:35:15,400 --> 00:35:18,960 Speaker 1: and magnetism, as you crank up the energy, the two 665 00:35:19,160 --> 00:35:22,080 Speaker 1: come together that the same strength, and the weak force 666 00:35:22,160 --> 00:35:26,879 Speaker 1: also merges together into one single strength. Really beautiful. As 667 00:35:26,880 --> 00:35:29,600 Speaker 1: you crank up the energy, the strong force also changes, 668 00:35:29,640 --> 00:35:32,360 Speaker 1: but it doesn't seem to grow together with the electroweak force. 669 00:35:32,680 --> 00:35:35,920 Speaker 1: It's like a parallel line. It's not coming together. So 670 00:35:35,960 --> 00:35:39,240 Speaker 1: that made people wonder like, hmmm, is there something missing. 671 00:35:39,719 --> 00:35:41,200 Speaker 1: And you know, we've talked a lot of times on 672 00:35:41,239 --> 00:35:44,280 Speaker 1: the show about the theory of supersymmetry. So the theory 673 00:35:44,320 --> 00:35:47,040 Speaker 1: that suggests that for every particle, there's a new kind 674 00:35:47,040 --> 00:35:50,480 Speaker 1: of mirror particle called the super particle, and it was 675 00:35:50,520 --> 00:35:54,200 Speaker 1: created for other reasons to explain why the Higgs mass 676 00:35:54,239 --> 00:35:56,719 Speaker 1: is so small, which is a mystery we don't understand. 677 00:35:57,239 --> 00:36:00,319 Speaker 1: And it's also this like beautiful example symmetry and the 678 00:36:00,320 --> 00:36:02,040 Speaker 1: math nerds love it and they would love for it 679 00:36:02,120 --> 00:36:04,480 Speaker 1: to be true in the universe. We've never seen any 680 00:36:04,520 --> 00:36:08,880 Speaker 1: evidence of it. But if you add supersymmetry to the theory, 681 00:36:08,920 --> 00:36:11,840 Speaker 1: then as you crank up the temperature, these forces do 682 00:36:11,960 --> 00:36:15,400 Speaker 1: grow together. Oh so it's like maybe we have a 683 00:36:15,400 --> 00:36:17,680 Speaker 1: missing piece. All this a piece over here that people 684 00:36:17,719 --> 00:36:20,640 Speaker 1: in bend for other reasons. If we stick it in boom, 685 00:36:20,760 --> 00:36:25,120 Speaker 1: then at high temperatures, everything comes together. Oh that's amazing. 686 00:36:25,160 --> 00:36:28,040 Speaker 1: Wouldn't that be beautiful. That was a real motivating factor 687 00:36:28,040 --> 00:36:33,799 Speaker 1: for people believing in supersymmetry. It felt like a huge clue. Unfortunately, 688 00:36:33,880 --> 00:36:37,040 Speaker 1: we turned on the large Handrun collider we didn't see supersymmetry. 689 00:36:37,239 --> 00:36:41,279 Speaker 1: So yeah, that would have been nice, But for now 690 00:36:41,320 --> 00:36:44,239 Speaker 1: we don't know how to unify the strong force with 691 00:36:44,320 --> 00:36:47,279 Speaker 1: the electroweak force. It might happen, It might be then 692 00:36:47,320 --> 00:36:50,120 Speaker 1: the early universe something happened to bring these together, but 693 00:36:50,239 --> 00:36:53,560 Speaker 1: we don't know how. And so we can theorize about 694 00:36:53,680 --> 00:36:56,600 Speaker 1: a gut theory, a grand unified theory, but we don't 695 00:36:56,640 --> 00:36:57,880 Speaker 1: know yet what that would look like. 696 00:36:58,160 --> 00:37:00,640 Speaker 3: But looking ahead to when we do, what will the 697 00:37:00,680 --> 00:37:03,960 Speaker 3: acronym be, will it be ooze electro week? 698 00:37:04,120 --> 00:37:08,520 Speaker 1: Strong Ooze Ooze I think is going to be a 699 00:37:08,520 --> 00:37:10,360 Speaker 1: strong contendert right. 700 00:37:10,200 --> 00:37:14,520 Speaker 3: It's important to figure this out, or so strong electro week? 701 00:37:14,719 --> 00:37:16,400 Speaker 3: I don't know, all right, Anyway, we can move on, 702 00:37:16,440 --> 00:37:18,520 Speaker 3: I guess to more important things. And if I am 703 00:37:18,560 --> 00:37:21,600 Speaker 3: remembering our list of five correctly. The last one is 704 00:37:21,680 --> 00:37:22,960 Speaker 3: gravity that we haven't. 705 00:37:22,760 --> 00:37:27,040 Speaker 1: Gotten to yet exactly. And this one is even harder because, 706 00:37:27,600 --> 00:37:31,239 Speaker 1: you know, unifying the strong force with electroweek is challenging 707 00:37:31,360 --> 00:37:33,960 Speaker 1: because they look different and the details are different. But 708 00:37:33,960 --> 00:37:36,560 Speaker 1: at least they're both quantum forces. You know, there are 709 00:37:36,560 --> 00:37:40,240 Speaker 1: fields involved, there's momentum propagating through those fields, all that stuff. 710 00:37:40,560 --> 00:37:43,680 Speaker 1: Gravity is a real head scratcher because it's a classical theory. 711 00:37:44,120 --> 00:37:47,200 Speaker 1: You know. Einstein tells us that mass bends space and 712 00:37:47,239 --> 00:37:49,960 Speaker 1: that space tells mass how to move, but it requires 713 00:37:50,040 --> 00:37:52,120 Speaker 1: like mass to have a location and to have a 714 00:37:52,160 --> 00:37:55,399 Speaker 1: classical trajectory to always have a place and a time 715 00:37:55,440 --> 00:37:57,319 Speaker 1: where it is, and to go from here to there 716 00:37:57,680 --> 00:38:02,000 Speaker 1: by going through space from here two there, and quantum 717 00:38:02,000 --> 00:38:03,759 Speaker 1: objects don't behave like that, so we just don't know 718 00:38:03,800 --> 00:38:06,840 Speaker 1: how to interface it with gravity. The search for quantum 719 00:38:06,880 --> 00:38:11,200 Speaker 1: gravity is, like, you know, the most frustrating and exciting 720 00:38:11,440 --> 00:38:15,279 Speaker 1: and terrifying and challenging thing happening in physics in the 721 00:38:15,360 --> 00:38:17,760 Speaker 1: last hundred years. We talked about a lot of times 722 00:38:17,760 --> 00:38:20,240 Speaker 1: on the show. If you could unify a gut theory 723 00:38:20,239 --> 00:38:22,960 Speaker 1: with gravity, you'd have a theory of everything, so you'd 724 00:38:22,960 --> 00:38:25,480 Speaker 1: have a toe and then you could make the theory 725 00:38:25,520 --> 00:38:26,840 Speaker 1: called the toe ooze. 726 00:38:26,960 --> 00:38:30,239 Speaker 3: I guess nice, I've already lost. What does toe stand for? 727 00:38:30,360 --> 00:38:32,440 Speaker 1: Again? Theory of every. 728 00:38:32,239 --> 00:38:33,640 Speaker 3: Theory of everything? Got it? 729 00:38:33,760 --> 00:38:33,960 Speaker 1: Gut? 730 00:38:34,040 --> 00:38:36,560 Speaker 3: And how is that different than the Grand unified theory? 731 00:38:36,840 --> 00:38:39,879 Speaker 1: Grand unified theory doesn't include gravity, So Grand unified theory 732 00:38:39,960 --> 00:38:41,400 Speaker 1: is electro week plus strong. 733 00:38:41,560 --> 00:38:41,840 Speaker 3: Okay. 734 00:38:42,000 --> 00:38:44,279 Speaker 1: If I want to add gravity, that's a theory of. 735 00:38:44,239 --> 00:38:47,160 Speaker 3: Everything, got it? Got it? Okay? So gravity is the 736 00:38:47,239 --> 00:38:50,560 Speaker 3: queen of the purple dragons exactly. 737 00:38:51,160 --> 00:38:57,000 Speaker 1: So force unification is very exciting and promising. Electromagnetism unified beautifully, 738 00:38:57,160 --> 00:38:59,920 Speaker 1: the weak force added beautifully, lots of Nobel prices won. 739 00:39:00,040 --> 00:39:03,719 Speaker 1: And beyond that is speculative, so grain unified theory that 740 00:39:03,800 --> 00:39:07,840 Speaker 1: includes the strong force, speculative quantum gravity that includes everything, 741 00:39:07,880 --> 00:39:11,520 Speaker 1: a theory of everything. Still very speculative, but we're hopeful 742 00:39:11,560 --> 00:39:12,600 Speaker 1: maybe we'll figure it out. 743 00:39:12,920 --> 00:39:16,640 Speaker 3: Okay, and we need to figure it out to really 744 00:39:16,880 --> 00:39:20,120 Speaker 3: understand the Big Bang? Is that fair to say? 745 00:39:20,440 --> 00:39:21,120 Speaker 1: Yeah? I think so. 746 00:39:21,520 --> 00:39:23,520 Speaker 3: Okay, All right, then let's take a break and when 747 00:39:23,560 --> 00:39:25,279 Speaker 3: we get back, we're gonna sort of go through the 748 00:39:25,280 --> 00:39:27,440 Speaker 3: timeline of the universe to try to understand how this 749 00:39:27,520 --> 00:39:29,720 Speaker 3: all played out. So we're gonna play it all going forward. 750 00:39:49,680 --> 00:39:52,680 Speaker 3: We're back, and Daniel's gonna start with the Big Bang 751 00:39:52,719 --> 00:39:54,880 Speaker 3: and take us forward and tell us about how these 752 00:39:54,920 --> 00:39:58,480 Speaker 3: forces split up question mark exactly. 753 00:39:59,040 --> 00:40:01,560 Speaker 1: So we've been telling them story sort of backwards. We've 754 00:40:01,600 --> 00:40:06,000 Speaker 1: been talking about taking the current universe at very low temperature, 755 00:40:06,040 --> 00:40:09,200 Speaker 1: everything is very cold, and heating it up to unify things. 756 00:40:09,640 --> 00:40:12,640 Speaker 1: But time flows forwards, right, and so let's instead tell 757 00:40:12,680 --> 00:40:15,400 Speaker 1: the story forwards also because that's the only chance we 758 00:40:15,480 --> 00:40:18,600 Speaker 1: have to potentially maybe answer Delayer's question, which was the 759 00:40:18,640 --> 00:40:21,520 Speaker 1: whole point of this podcast, and so we're going to 760 00:40:21,560 --> 00:40:24,200 Speaker 1: talk about the timeline of the early universe, and we're 761 00:40:24,200 --> 00:40:27,000 Speaker 1: going to use some crazy numbers to talk about time. 762 00:40:27,640 --> 00:40:30,640 Speaker 1: And so what do these times mean. Remember that we 763 00:40:30,719 --> 00:40:33,400 Speaker 1: don't have a lot of data for these very early moments. 764 00:40:33,760 --> 00:40:35,799 Speaker 1: You mentioned at the top of the podcast how we've 765 00:40:36,000 --> 00:40:38,279 Speaker 1: seen the Big Bang. We've actually only seen back to 766 00:40:38,320 --> 00:40:41,160 Speaker 1: like three hundred and eighty thousand years after the Big Bang, 767 00:40:41,320 --> 00:40:44,279 Speaker 1: that's when photons were made. So a lot of this 768 00:40:44,320 --> 00:40:47,600 Speaker 1: stuff is speculated. But essentially, you take our current model 769 00:40:47,640 --> 00:40:51,520 Speaker 1: of the universe expanding, you run it backwards to predict 770 00:40:51,520 --> 00:40:55,200 Speaker 1: what would have happened deep, deep in early history. So 771 00:40:55,560 --> 00:40:58,080 Speaker 1: let's go as far back as we can. If you 772 00:40:58,160 --> 00:41:00,759 Speaker 1: run the clock back thirteen point eight billion years, you 773 00:41:00,760 --> 00:41:03,240 Speaker 1: get to a place where you would need quantum gravity 774 00:41:03,280 --> 00:41:05,759 Speaker 1: to continue. Like, we don't know how to predict what 775 00:41:05,800 --> 00:41:10,040 Speaker 1: would happen, because quantum mechanics is relevant and gravity is relevant. 776 00:41:10,520 --> 00:41:13,200 Speaker 1: And so we call this time before the Plank time, 777 00:41:13,239 --> 00:41:15,560 Speaker 1: because you know, Plank is one of the grandfathers of 778 00:41:15,640 --> 00:41:18,800 Speaker 1: quantum physics, or this is the Plank epoch. So before 779 00:41:19,239 --> 00:41:22,440 Speaker 1: ten to the minus forty three seconds in the universe, 780 00:41:22,480 --> 00:41:24,800 Speaker 1: you can't go all the way back to T equals zero, 781 00:41:25,280 --> 00:41:27,120 Speaker 1: because we don't know how to do that, right, Like 782 00:41:27,400 --> 00:41:31,080 Speaker 1: general relativity predicts a singularity, quantum mechanics says you can't 783 00:41:31,080 --> 00:41:33,200 Speaker 1: have that, So like, how do you even get to 784 00:41:33,200 --> 00:41:36,040 Speaker 1: T equals zero? So before ten of the minus forty 785 00:41:36,040 --> 00:41:38,840 Speaker 1: three seconds, we say that's the Plank epoch. And the 786 00:41:38,960 --> 00:41:42,160 Speaker 1: laws that are involved are some theory of everything, some 787 00:41:42,400 --> 00:41:46,400 Speaker 1: quantum gravity that we don't know. It's all the forces all. 788 00:41:46,360 --> 00:41:55,880 Speaker 3: Unified, so it's zero point forty three zeros one seconds before. Okay, 789 00:41:55,880 --> 00:41:59,120 Speaker 3: all right, so we're really close to zero and all 790 00:41:59,120 --> 00:42:01,799 Speaker 3: the forces need to beied, so we don't know what's 791 00:42:01,840 --> 00:42:03,839 Speaker 3: going on, but that's where we need to get that's right. 792 00:42:03,880 --> 00:42:06,080 Speaker 1: And Delai are also asked like what is the content 793 00:42:06,160 --> 00:42:08,480 Speaker 1: of the universe at every moment here? Which I think 794 00:42:08,520 --> 00:42:11,479 Speaker 1: is a really fun question. And at this early point 795 00:42:11,480 --> 00:42:14,319 Speaker 1: in the universe, it's not meaningful to talk about particles 796 00:42:14,800 --> 00:42:17,040 Speaker 1: because we don't think of the universe as filled with 797 00:42:17,120 --> 00:42:20,520 Speaker 1: quantum fields. I remember here, we're always talking effective theories, right, 798 00:42:20,600 --> 00:42:23,960 Speaker 1: what is a useful way to describe the universe and 799 00:42:24,040 --> 00:42:27,520 Speaker 1: to talk about particles? You need energy in quantum fields 800 00:42:27,520 --> 00:42:30,840 Speaker 1: to be a useful description of the universe, and we 801 00:42:30,880 --> 00:42:33,520 Speaker 1: don't know what quantum gravity will look like like, maybe 802 00:42:33,560 --> 00:42:35,439 Speaker 1: it gets rid of quantum fields, maybe it has something 803 00:42:35,480 --> 00:42:38,320 Speaker 1: completely different. It's totally new and it tells a different 804 00:42:38,360 --> 00:42:41,320 Speaker 1: story about the universe. So we can't even talk about, 805 00:42:41,360 --> 00:42:45,120 Speaker 1: like what particles were around, because particles are excitations in 806 00:42:45,160 --> 00:42:47,120 Speaker 1: a quantum field, and we don't know if those are 807 00:42:47,160 --> 00:42:48,879 Speaker 1: going to be part of the theory. We don't have 808 00:42:48,960 --> 00:42:51,840 Speaker 1: the theory at all, so we don't know what effective 809 00:42:51,840 --> 00:42:54,040 Speaker 1: descriptions are going to emerge. We don't know what the 810 00:42:54,040 --> 00:42:57,759 Speaker 1: fundamental theory is. We don't know what the useful calculational 811 00:42:57,800 --> 00:43:00,000 Speaker 1: tools are. We can't even really tell you. 812 00:43:00,160 --> 00:43:02,120 Speaker 3: Wow, okay, quite exciting, big. 813 00:43:02,040 --> 00:43:06,120 Speaker 1: Question mark, big purple dragons, all right. So as the 814 00:43:06,200 --> 00:43:09,759 Speaker 1: universe expands, it cools, and so in the next era, 815 00:43:09,840 --> 00:43:12,440 Speaker 1: which we call the gut epic nice, which is between 816 00:43:12,440 --> 00:43:14,360 Speaker 1: ten of the minus forty three seconds and ten of 817 00:43:14,360 --> 00:43:17,960 Speaker 1: the minus thirty six seconds. This is after the threshold 818 00:43:17,960 --> 00:43:19,960 Speaker 1: of ten of the minus forty three seconds, when the 819 00:43:20,040 --> 00:43:23,600 Speaker 1: universe has cooled enough that gravity splits off from the 820 00:43:23,640 --> 00:43:24,320 Speaker 1: other forces. 821 00:43:24,680 --> 00:43:27,399 Speaker 3: So we have in our heads an order in which 822 00:43:27,440 --> 00:43:31,759 Speaker 3: we expect the forces. Yeah, to stop unifying, and we 823 00:43:31,800 --> 00:43:35,880 Speaker 3: expect gravity to be one of the first to stop yesterrying. Okay, 824 00:43:35,880 --> 00:43:39,640 Speaker 3: why because it's so weird and has always been the troublemaker. 825 00:43:40,440 --> 00:43:43,040 Speaker 1: This is speculative, right. It could be that we're wrong 826 00:43:43,080 --> 00:43:46,000 Speaker 1: about this. It's just that in our heads it makes 827 00:43:46,040 --> 00:43:49,279 Speaker 1: more sense to combine them in the reverse order, like 828 00:43:49,360 --> 00:43:52,120 Speaker 1: to combine the strong force with electri week and then 829 00:43:52,280 --> 00:43:55,200 Speaker 1: unify all the quantum theories with gravity. But we could 830 00:43:55,239 --> 00:43:57,520 Speaker 1: be wrong, okay, and it could be that, like you know, 831 00:43:57,560 --> 00:43:59,600 Speaker 1: we got to do this in another order. So everything 832 00:43:59,600 --> 00:44:01,880 Speaker 1: here is still very very speculative, right, depends on the 833 00:44:01,880 --> 00:44:05,000 Speaker 1: details of quantic gravity, which we don't have. This next 834 00:44:05,000 --> 00:44:07,399 Speaker 1: segment depends on the details of the gut theory, which 835 00:44:07,480 --> 00:44:09,560 Speaker 1: we don't have. So this is one way it could 836 00:44:09,600 --> 00:44:13,600 Speaker 1: have gone, not necessarily definitive at all, okay, right, But 837 00:44:13,960 --> 00:44:17,080 Speaker 1: in this version, then you know, the universe cools to 838 00:44:17,120 --> 00:44:19,520 Speaker 1: a point where we can start to ignore gravity and 839 00:44:19,560 --> 00:44:22,040 Speaker 1: we can only worry about the quantum forces when we're 840 00:44:22,040 --> 00:44:25,560 Speaker 1: making predictions. Right, and gravity is the weakest of all 841 00:44:25,600 --> 00:44:28,439 Speaker 1: these things. And as the universe gets less and less dense, 842 00:44:28,480 --> 00:44:31,400 Speaker 1: gravity gets less and less relevant, and so it breaks 843 00:44:31,440 --> 00:44:34,480 Speaker 1: off faster, right, that makes sense. And at this point 844 00:44:34,520 --> 00:44:38,080 Speaker 1: here we have gravity, which we know, plus all the 845 00:44:38,160 --> 00:44:41,360 Speaker 1: quantum forces unified into one force, which we don't have 846 00:44:41,400 --> 00:44:44,520 Speaker 1: a theory for. We just have like a policeholder for it. 847 00:44:44,640 --> 00:44:47,359 Speaker 1: But we can't talk about particles now because we have 848 00:44:47,640 --> 00:44:51,160 Speaker 1: the universe mostly dominated by quantum fields. But we don't 849 00:44:51,160 --> 00:44:53,799 Speaker 1: know what those fields are, right, They're the fields that 850 00:44:53,840 --> 00:44:57,040 Speaker 1: are part of some theory. We don't have the gut field, right, 851 00:44:57,120 --> 00:45:00,279 Speaker 1: And we talk about particles in those fields. We call 852 00:45:00,360 --> 00:45:02,960 Speaker 1: them the x boson the y boson. There might be 853 00:45:03,000 --> 00:45:06,480 Speaker 1: some unified gut force, and these are the mediators of it. 854 00:45:06,560 --> 00:45:08,880 Speaker 1: I'm sounding like I'm waving my hands a lot because 855 00:45:08,880 --> 00:45:11,160 Speaker 1: we don't really know because again we don't know how 856 00:45:11,200 --> 00:45:13,279 Speaker 1: to unify the strong force. So this is just like 857 00:45:13,480 --> 00:45:15,680 Speaker 1: a placeholder for what might have happened. 858 00:45:15,960 --> 00:45:18,760 Speaker 3: But like the creation of the universe is so beautiful, 859 00:45:18,760 --> 00:45:21,640 Speaker 3: and you all came up with the gut force, like 860 00:45:22,280 --> 00:45:25,080 Speaker 3: I just I you know, every time you'll have a 861 00:45:25,160 --> 00:45:28,239 Speaker 3: chance to impress, but it's a gut to then just 862 00:45:28,360 --> 00:45:31,160 Speaker 3: stick with grand unified force and never allow yourself to 863 00:45:31,239 --> 00:45:32,080 Speaker 3: use the acronym. 864 00:45:32,239 --> 00:45:34,799 Speaker 1: But right, anyway, I'll call it the grand ut force 865 00:45:35,000 --> 00:45:35,279 Speaker 1: of that. 866 00:45:35,480 --> 00:45:38,040 Speaker 3: Now, forget it. It's too late. It's too late. You 867 00:45:38,080 --> 00:45:39,360 Speaker 3: already did it? Move on? 868 00:45:40,080 --> 00:45:43,600 Speaker 1: Gun, Yeah, I know, all right. So at this stage 869 00:45:43,680 --> 00:45:46,160 Speaker 1: we think we have a gut force, a single unified 870 00:45:46,200 --> 00:45:49,400 Speaker 1: force carried by X and Y bosons, but we don't 871 00:45:49,440 --> 00:45:53,080 Speaker 1: really know, right, It's it's speculative. The universe continues to 872 00:45:53,120 --> 00:45:56,280 Speaker 1: expand continues to cool ten to minus thirty six seconds. 873 00:45:56,840 --> 00:45:59,839 Speaker 1: Now the strong force breaks off from the electra week 874 00:46:00,040 --> 00:46:02,960 Speaker 1: and that we have two forces, right, And this is 875 00:46:03,000 --> 00:46:06,360 Speaker 1: the era that we can describe very accurately with our physics, 876 00:46:06,400 --> 00:46:08,520 Speaker 1: because we know about the electroweak force, and we know 877 00:46:08,560 --> 00:46:11,640 Speaker 1: about the strong force, and the universe is cooled, and 878 00:46:11,680 --> 00:46:14,440 Speaker 1: as it cools, these two forces start to behave differently. 879 00:46:14,840 --> 00:46:19,200 Speaker 1: So again, the fundamental, true, underlying reality is not changing 880 00:46:19,200 --> 00:46:22,440 Speaker 1: the laws of physics somehow, but how we describe it 881 00:46:22,480 --> 00:46:25,200 Speaker 1: effectively changes. Like, it makes sense now to talk about 882 00:46:25,200 --> 00:46:28,840 Speaker 1: the strong force is different from the electroweak force because 883 00:46:28,880 --> 00:46:32,120 Speaker 1: the universe is cooler. We're in a different phase where 884 00:46:32,120 --> 00:46:34,480 Speaker 1: the strong force acts very different, and so it makes 885 00:46:34,520 --> 00:46:38,600 Speaker 1: sense to treat those calculations separately, right, instead of unifying them. 886 00:46:38,840 --> 00:46:41,040 Speaker 1: The elephant's tail has run off by itself. 887 00:46:42,120 --> 00:46:45,480 Speaker 3: Okay, but so now we would still have elementary particles 888 00:46:45,520 --> 00:46:48,840 Speaker 3: and antiparticles, and do we know what kind of fields 889 00:46:48,840 --> 00:46:51,560 Speaker 3: we're dealing with here? Is stuff pretty normal? 890 00:46:51,880 --> 00:46:55,239 Speaker 1: Yes? So now the content of the universe are particles 891 00:46:55,280 --> 00:46:59,000 Speaker 1: we're familiar with. They are the electroweak particles, the W, 892 00:46:59,320 --> 00:47:03,439 Speaker 1: the Z, the photon. There are matter particles, quarks, electrons, 893 00:47:03,719 --> 00:47:07,240 Speaker 1: all these kind of familiar particles. Right, So the universe 894 00:47:07,280 --> 00:47:10,000 Speaker 1: is cooled and broken into these familiar fields, and we 895 00:47:10,040 --> 00:47:13,000 Speaker 1: have ripples in those fields. It's the content of the universe. 896 00:47:13,760 --> 00:47:18,800 Speaker 1: Then something crazy happens. The universe starts to inflate, meaning 897 00:47:19,360 --> 00:47:22,239 Speaker 1: very very rapid expansion. So we were expanding before. Now 898 00:47:22,280 --> 00:47:24,799 Speaker 1: we have kicked it into high gear. And this part 899 00:47:24,960 --> 00:47:28,480 Speaker 1: also very speculative, but we think the universe expanded by 900 00:47:28,480 --> 00:47:31,239 Speaker 1: a factor of like ten to the thirty in a 901 00:47:31,480 --> 00:47:34,520 Speaker 1: very very short window of time. That's the equivalent of 902 00:47:34,560 --> 00:47:37,400 Speaker 1: taking like a cantelope and expanding it to the size 903 00:47:37,440 --> 00:47:41,359 Speaker 1: of the observable universe. So like really big deal. 904 00:47:41,640 --> 00:47:41,799 Speaker 3: Yea. 905 00:47:42,120 --> 00:47:44,480 Speaker 1: And remember we don't know the size of the universe. 906 00:47:44,680 --> 00:47:47,279 Speaker 1: So the universe could be infinite, which means it went 907 00:47:47,320 --> 00:47:52,360 Speaker 1: from infinite to more infinite, right, or it could have 908 00:47:52,360 --> 00:47:55,280 Speaker 1: been finite, so that it went from small or large 909 00:47:55,320 --> 00:47:58,319 Speaker 1: and finite to bigger. Right, We just don't know it 910 00:47:58,400 --> 00:48:01,680 Speaker 1: was the universe is infinite or fine. And exactly when 911 00:48:01,680 --> 00:48:05,480 Speaker 1: this happened depends on the details of your grain unified theory, etcetera, etc. 912 00:48:06,120 --> 00:48:09,280 Speaker 1: But the crucial thing is that the universe became very dilute, 913 00:48:09,600 --> 00:48:12,320 Speaker 1: like you had those particles already, and then the universe 914 00:48:12,360 --> 00:48:16,920 Speaker 1: spread out massively, so now there's just not a lot 915 00:48:16,960 --> 00:48:19,360 Speaker 1: of particles out there, and so the universe is suddenly 916 00:48:19,440 --> 00:48:24,600 Speaker 1: very very cold, right, very very dilute. Then inflation ends, 917 00:48:24,719 --> 00:48:27,720 Speaker 1: So all this energy does powering the expansion of the universe, 918 00:48:27,800 --> 00:48:31,719 Speaker 1: the inflation that gets dumped into the other quantum fields. 919 00:48:32,239 --> 00:48:35,760 Speaker 1: That energy gets dumped into quark fields and photon fields 920 00:48:35,800 --> 00:48:38,360 Speaker 1: and all sorts of stuff. And so now the universe 921 00:48:38,400 --> 00:48:42,000 Speaker 1: becomes very very dense and hot. Again. This is called reheating, 922 00:48:42,719 --> 00:48:44,799 Speaker 1: and this is really the beginning of what we call 923 00:48:44,880 --> 00:48:49,200 Speaker 1: the hot Big Bang. Before that, very very uncertain. After that, 924 00:48:49,560 --> 00:48:52,719 Speaker 1: things are described very very well. Everything we just just 925 00:48:52,760 --> 00:48:55,800 Speaker 1: set up to now is speculative and could be totally wrong. 926 00:48:56,480 --> 00:48:58,799 Speaker 1: Everything we're going to say from now on is very 927 00:48:58,880 --> 00:49:01,480 Speaker 1: very well established what we mean when we say the 928 00:49:01,520 --> 00:49:06,000 Speaker 1: Big Bang from this moment somehow, maybe via inflation, dumping 929 00:49:06,080 --> 00:49:09,040 Speaker 1: all the energy and reheating all the fields. The universe 930 00:49:09,120 --> 00:49:12,239 Speaker 1: is very dense and very filled with familiar particles. 931 00:49:12,520 --> 00:49:16,920 Speaker 3: And are we still dealing with the first second of existence. 932 00:49:17,520 --> 00:49:20,080 Speaker 1: We are up to ten to the minus twelve. 933 00:49:19,960 --> 00:49:23,360 Speaker 3: Seconds, so still the first second. 934 00:49:23,440 --> 00:49:26,040 Speaker 1: We're still dealing with the first trillionth of a second. 935 00:49:26,200 --> 00:49:28,480 Speaker 3: Yeah, so that's pretty amazing that. 936 00:49:28,840 --> 00:49:31,200 Speaker 1: Yes, yeah, a lot of stuff has happened so far, 937 00:49:31,680 --> 00:49:35,000 Speaker 1: just a few ticks on the clock, absolutely, and then 938 00:49:35,040 --> 00:49:38,000 Speaker 1: something really exciting happens, which is look, you've created all 939 00:49:38,000 --> 00:49:41,160 Speaker 1: these particles. You have matter particles, you have anti matter particles. 940 00:49:41,440 --> 00:49:45,399 Speaker 1: Most of those annihilate, so universe filled with matter, and 941 00:49:45,440 --> 00:49:49,040 Speaker 1: then those particles find each other annihilate, and now the 942 00:49:49,120 --> 00:49:53,000 Speaker 1: universe mostly filled with radiation, with a little bit of 943 00:49:53,000 --> 00:49:55,640 Speaker 1: matter left over because you had a little bit more 944 00:49:55,680 --> 00:49:58,880 Speaker 1: matter than you had antimatter, and that little bit of 945 00:49:58,920 --> 00:50:01,680 Speaker 1: extra is what turned in into me and you and 946 00:50:01,760 --> 00:50:04,840 Speaker 1: most of the stuff in the universe is time little 947 00:50:04,840 --> 00:50:07,360 Speaker 1: extra bit of matter. We don't know why there was 948 00:50:07,400 --> 00:50:11,000 Speaker 1: that asymmetry. We can't understand it. We have some explanations 949 00:50:11,000 --> 00:50:13,720 Speaker 1: for it, but not nearly enough to explain what we see. 950 00:50:13,840 --> 00:50:16,000 Speaker 3: Wait, so that tiny little bit of matter is all 951 00:50:16,040 --> 00:50:18,279 Speaker 3: of the matter that still exists today. That seems like 952 00:50:18,280 --> 00:50:19,000 Speaker 3: a lot of matter. 953 00:50:19,760 --> 00:50:21,840 Speaker 1: It's a lot of matter, but it's a tiny fraction 954 00:50:22,160 --> 00:50:23,560 Speaker 1: of the original amount of matter. 955 00:50:23,640 --> 00:50:25,480 Speaker 3: All right, I guess it's all about perspective. 956 00:50:25,640 --> 00:50:29,799 Speaker 1: But the universe was dominated by radiation, like most of 957 00:50:29,840 --> 00:50:31,799 Speaker 1: the energy in the universe at that time was in 958 00:50:31,880 --> 00:50:37,400 Speaker 1: photons from annihilation. Okay, And so then things keep cooling, 959 00:50:37,880 --> 00:50:40,200 Speaker 1: and when we get to ten of the minus twelve seconds, 960 00:50:40,480 --> 00:50:44,040 Speaker 1: this is another phase transition of the universe where we're 961 00:50:44,040 --> 00:50:48,120 Speaker 1: now cool enough that it matters that the weak force 962 00:50:48,320 --> 00:50:51,520 Speaker 1: has heavy massive bosons. And so now we say the 963 00:50:51,520 --> 00:50:55,120 Speaker 1: weak force breaks off from electromagnetism, by which we mean, 964 00:50:55,400 --> 00:50:57,239 Speaker 1: you know, none of the fundamental rules have changed. The 965 00:50:57,280 --> 00:50:59,360 Speaker 1: only thing that's changed is the temperature of the universe. 966 00:50:59,760 --> 00:51:02,040 Speaker 1: But now it doesn't make sense to treat these two 967 00:51:02,040 --> 00:51:05,200 Speaker 1: things together because it matters that one of them has 968 00:51:05,239 --> 00:51:08,000 Speaker 1: really massive bosons and the other one has a massless boson. 969 00:51:08,360 --> 00:51:11,160 Speaker 1: They start to act very differently. Right, We're now hiking 970 00:51:11,200 --> 00:51:13,640 Speaker 1: over those mountains instead of flying over them, and it 971 00:51:13,760 --> 00:51:16,680 Speaker 1: matters if you're carrying a really heavy pack or not. 972 00:51:17,520 --> 00:51:20,480 Speaker 1: And so we break those up and we treat them differently. 973 00:51:20,920 --> 00:51:21,720 Speaker 1: Does that make sense? 974 00:51:21,880 --> 00:51:25,160 Speaker 3: How did this all happen in a second? My brain 975 00:51:25,239 --> 00:51:27,200 Speaker 3: is kind of prepped on something else. How did this 976 00:51:27,200 --> 00:51:29,800 Speaker 3: all happen in a second? And how did we figure 977 00:51:29,840 --> 00:51:33,799 Speaker 3: out the timing down to the point? Oh oh oh? 978 00:51:33,880 --> 00:51:35,680 Speaker 3: But like wow, I. 979 00:51:35,560 --> 00:51:37,560 Speaker 1: Know it takes me like an hour to get up 980 00:51:37,560 --> 00:51:39,880 Speaker 1: and have coffee even think about getting anything done, and 981 00:51:39,920 --> 00:51:43,719 Speaker 1: by that time, the universe is already done all this stuff. Yeah, 982 00:51:43,719 --> 00:51:46,200 Speaker 1: it's crazy, and it's a fair question. How do we 983 00:51:46,239 --> 00:51:49,880 Speaker 1: know this stuff? We know this bike extrapolating our model 984 00:51:49,960 --> 00:51:53,240 Speaker 1: backwards in time. And these models we've built from lots 985 00:51:53,239 --> 00:51:57,200 Speaker 1: of moths of observations, the cosmic, microwave, background radiation, large 986 00:51:57,200 --> 00:52:00,600 Speaker 1: scale structure bearing on acoustic oscillation, and we've talked about 987 00:52:00,600 --> 00:52:02,880 Speaker 1: all those things in the podcast dig into those. We 988 00:52:02,920 --> 00:52:05,480 Speaker 1: have really really well constrained models for a lot of 989 00:52:05,520 --> 00:52:08,000 Speaker 1: this stuff. Those models don't work perfectly. There's still like 990 00:52:08,040 --> 00:52:11,040 Speaker 1: mysteries right now about that expansion. It's called the hubble tension. 991 00:52:11,600 --> 00:52:14,480 Speaker 1: So there's definitely things to learn. But it's a pretty 992 00:52:14,480 --> 00:52:16,880 Speaker 1: well established timeline after the reheating. 993 00:52:17,360 --> 00:52:19,520 Speaker 3: That's incredible. That was one hot second. 994 00:52:19,840 --> 00:52:23,719 Speaker 1: Yeah, it was, and it's still going. Between ten of 995 00:52:23,760 --> 00:52:26,040 Speaker 1: the minus twelve seconds and ten of the minus six 996 00:52:26,440 --> 00:52:28,680 Speaker 1: you still have enough stuff in the universe to have 997 00:52:28,719 --> 00:52:32,080 Speaker 1: a quark gluon plasma. Things are still pretty dense, so 998 00:52:32,200 --> 00:52:34,839 Speaker 1: quarks and gluons are floating around, and it's still hot 999 00:52:35,000 --> 00:52:38,120 Speaker 1: enough that they're not bound into objects, right, they can 1000 00:52:38,239 --> 00:52:41,160 Speaker 1: just smooth around, like at the heart of a neutron star. 1001 00:52:41,920 --> 00:52:44,240 Speaker 1: And then around ten of the minus six seconds, things 1002 00:52:44,280 --> 00:52:48,000 Speaker 1: cool down and you form protons and neutrons, and then 1003 00:52:48,080 --> 00:52:52,320 Speaker 1: for like literally two minutes, there's enough heat and temperature 1004 00:52:52,320 --> 00:52:54,960 Speaker 1: in the universe for fusion to happen, like the kind 1005 00:52:54,960 --> 00:52:57,080 Speaker 1: of fusion at the heart of stars that like makes 1006 00:52:57,120 --> 00:53:01,320 Speaker 1: heavy stuff. That happened in the universe for a hot minute, 1007 00:53:01,560 --> 00:53:03,239 Speaker 1: and it made it a little bit of helium and 1008 00:53:03,280 --> 00:53:07,439 Speaker 1: a little bit of lithium, and that's called Big Bang nucleosynthesis. 1009 00:53:07,840 --> 00:53:10,799 Speaker 1: And that's very very sensitive to loss of the details. 1010 00:53:11,000 --> 00:53:13,600 Speaker 1: How hot was it, how many quarks were there. We 1011 00:53:13,719 --> 00:53:16,440 Speaker 1: know a lot about the early universe just from measuring 1012 00:53:16,520 --> 00:53:20,200 Speaker 1: how much helium and lithium was made in that first minute, 1013 00:53:20,520 --> 00:53:23,759 Speaker 1: super duper powerful test of the early universe. And then 1014 00:53:23,880 --> 00:53:27,239 Speaker 1: four hundred thousand years later, of course things cool down 1015 00:53:27,360 --> 00:53:30,160 Speaker 1: and electrons find their protons and we get neutral atoms, 1016 00:53:30,160 --> 00:53:33,040 Speaker 1: and the universe becomes transparent and we see the cosmic 1017 00:53:33,080 --> 00:53:36,600 Speaker 1: microwave background radiation. So that's the sort of timeline in 1018 00:53:36,640 --> 00:53:39,120 Speaker 1: the universe from the beginning when it was really hot, 1019 00:53:39,440 --> 00:53:43,760 Speaker 1: cooling down and we enter different phases of effective descriptions 1020 00:53:43,840 --> 00:53:44,719 Speaker 1: of the universe. 1021 00:53:45,320 --> 00:53:47,920 Speaker 3: It feels like the universe like burned out, like it 1022 00:53:47,960 --> 00:53:50,600 Speaker 3: had its first second was really really active, and then 1023 00:53:50,600 --> 00:53:52,879 Speaker 3: it was like, ah, you know what I did too much? 1024 00:53:53,080 --> 00:53:55,520 Speaker 3: I did too much, and then it just really slows down, 1025 00:53:55,680 --> 00:53:57,880 Speaker 3: and yeah, I. 1026 00:53:57,880 --> 00:54:00,680 Speaker 1: Don't think it has any regrets. You know, what happened 1027 00:54:00,719 --> 00:54:03,759 Speaker 1: in the universe is beautiful, Yes it is. So back 1028 00:54:03,800 --> 00:54:07,160 Speaker 1: to Delair's question, he asked, what was the form of energy? 1029 00:54:07,320 --> 00:54:10,400 Speaker 1: Was it in photons? And so you know, when the 1030 00:54:10,440 --> 00:54:13,200 Speaker 1: grain unified theory was ruling as the effective theory of 1031 00:54:13,239 --> 00:54:14,960 Speaker 1: the universe, we don't know because we don't know what 1032 00:54:14,960 --> 00:54:17,040 Speaker 1: the theory looked like. We call it the X and 1033 00:54:17,080 --> 00:54:20,440 Speaker 1: the Y particles, just the sort of placeholders because some 1034 00:54:20,560 --> 00:54:23,879 Speaker 1: candidates have those two bosons in them, but we don't know. 1035 00:54:24,480 --> 00:54:27,799 Speaker 1: He asks, what caused the force to break down? It's 1036 00:54:27,840 --> 00:54:30,400 Speaker 1: just that the universe cools, and so then the rules 1037 00:54:30,440 --> 00:54:33,560 Speaker 1: you would use to describe things in a useful way change, 1038 00:54:34,040 --> 00:54:36,840 Speaker 1: not that the rules of the underlying universe have changed, 1039 00:54:37,000 --> 00:54:40,400 Speaker 1: just to our effective theories, our descriptions of the universe change. 1040 00:54:41,120 --> 00:54:43,799 Speaker 1: He asked, what were the steps of the breakdown? So 1041 00:54:43,840 --> 00:54:46,040 Speaker 1: we think the gravity broke off first, and then the 1042 00:54:46,040 --> 00:54:50,239 Speaker 1: strong force, and then the weak force, and now electromagnetism. 1043 00:54:50,640 --> 00:54:53,320 Speaker 1: He asks, also, is there any relationship between the breakdown 1044 00:54:53,320 --> 00:54:56,319 Speaker 1: of this force and the inflation? Did one cause the other? 1045 00:54:56,960 --> 00:54:58,799 Speaker 1: So we don't know for sure, because a lot of 1046 00:54:58,800 --> 00:55:01,000 Speaker 1: this is before the time that we can study really 1047 00:55:01,000 --> 00:55:05,160 Speaker 1: really well. Inflation is still speculative, and how grand unified 1048 00:55:05,160 --> 00:55:08,720 Speaker 1: theories treat inflation depends on the particular grand unified theory. 1049 00:55:09,200 --> 00:55:11,520 Speaker 1: So there's a complicated interplay there that we just don't 1050 00:55:11,520 --> 00:55:13,160 Speaker 1: know about really concretely. 1051 00:55:14,000 --> 00:55:17,279 Speaker 3: So what I got from your conversation with Ethan was 1052 00:55:17,280 --> 00:55:19,640 Speaker 3: that there's maybe a lot of disagreement about a lot 1053 00:55:19,640 --> 00:55:24,319 Speaker 3: of stuff. And so if I talked to, you know, 1054 00:55:24,640 --> 00:55:27,560 Speaker 3: ten different people who had the same job as you, 1055 00:55:28,080 --> 00:55:29,839 Speaker 3: and they were given the same set of I know 1056 00:55:30,120 --> 00:55:33,120 Speaker 3: none of them as good as you, of course, of course, uh, 1057 00:55:33,160 --> 00:55:33,520 Speaker 3: And they were. 1058 00:55:33,480 --> 00:55:35,320 Speaker 1: Given you're going to talk to other particle physicists. 1059 00:55:35,400 --> 00:55:40,080 Speaker 3: Never, no, never, never. I promise you're being very controlling, Daniel. 1060 00:55:41,800 --> 00:55:43,320 Speaker 1: I suddenly have this feelings of jealousy. 1061 00:55:43,320 --> 00:55:45,239 Speaker 3: Oh my god, I'll get over it all right. So 1062 00:55:46,320 --> 00:55:48,520 Speaker 3: that if those sets of questions got sent to ten 1063 00:55:48,640 --> 00:55:54,040 Speaker 3: other particle physicists, would they give a roughly similar description 1064 00:55:54,440 --> 00:55:56,640 Speaker 3: or talk as you gave, or would they have a 1065 00:55:56,800 --> 00:56:00,239 Speaker 3: very different sense of like what we know in where 1066 00:56:00,280 --> 00:56:01,239 Speaker 3: the uncertainties are. 1067 00:56:01,640 --> 00:56:04,240 Speaker 1: I think that we would all agree on the later 1068 00:56:04,320 --> 00:56:07,120 Speaker 1: stages because those are things we've measured. We are pretty 1069 00:56:07,120 --> 00:56:11,759 Speaker 1: confident about the very early universe stuff inflation and before that, 1070 00:56:12,280 --> 00:56:16,040 Speaker 1: very speculative. You might get different opinions about what's most 1071 00:56:16,120 --> 00:56:19,640 Speaker 1: likely to work out eventually as a model, And I 1072 00:56:19,680 --> 00:56:22,880 Speaker 1: think probably I have an unusual philosophical take for a 1073 00:56:22,920 --> 00:56:27,919 Speaker 1: particle physicists thinking about emergence and effective theories differently than 1074 00:56:28,280 --> 00:56:32,759 Speaker 1: many particle physicists. But I'm not sure. Okay, maybe I'll 1075 00:56:32,760 --> 00:56:35,359 Speaker 1: ask them over lunch and try not to disturb their 1076 00:56:35,400 --> 00:56:36,960 Speaker 1: guts with too many ease. 1077 00:56:39,719 --> 00:56:42,120 Speaker 3: Well, I hope that goes well. Let me know, this 1078 00:56:42,320 --> 00:56:44,200 Speaker 3: was a ton of fun and we learned a bunch. 1079 00:56:44,400 --> 00:56:46,360 Speaker 3: Let's hear what our listener has to say. 1080 00:56:46,640 --> 00:56:50,319 Speaker 2: Thank you Daniel and Kelly for answering my question. That 1081 00:56:50,520 --> 00:56:53,680 Speaker 2: was really great. I have a better understanding now of 1082 00:56:54,239 --> 00:56:57,160 Speaker 2: the early stages of the universe, and I think what 1083 00:56:57,320 --> 00:57:01,680 Speaker 2: health in that clarification is that two approaches you used 1084 00:57:01,680 --> 00:57:04,640 Speaker 2: to address the issues or the questions. One is the 1085 00:57:04,760 --> 00:57:07,560 Speaker 2: energy level, what happens when we crank up the energy, 1086 00:57:08,160 --> 00:57:12,280 Speaker 2: And the second approach was the chronologically how the universe 1087 00:57:12,360 --> 00:57:18,280 Speaker 2: evolved and the forces got broken down, and also what 1088 00:57:19,160 --> 00:57:24,640 Speaker 2: helped understanding it also the example of the different phases 1089 00:57:24,680 --> 00:57:27,280 Speaker 2: of the water. So looking at the universe and the 1090 00:57:27,320 --> 00:57:30,960 Speaker 2: forces in that way also may it makes it easier 1091 00:57:31,040 --> 00:57:34,920 Speaker 2: to understand. And also I like very much the clarifying 1092 00:57:35,000 --> 00:57:38,800 Speaker 2: question by Kelly. It seemed like she was channeling my questions. 1093 00:57:38,920 --> 00:57:43,080 Speaker 2: So that was really very very great help in getting 1094 00:57:43,160 --> 00:57:46,640 Speaker 2: Daniel to explain the answers in a very clear way 1095 00:57:46,960 --> 00:57:50,800 Speaker 2: and very logically. So once again, thank you very much. 1096 00:57:50,880 --> 00:57:54,920 Speaker 2: It was really fun listening to it and I enjoyed it. 1097 00:57:54,960 --> 00:57:57,720 Speaker 1: Thank you by all right. Thank you very much Delaire 1098 00:57:57,760 --> 00:58:00,600 Speaker 1: for sending in your question and for writing with us 1099 00:58:00,600 --> 00:58:03,920 Speaker 1: on this journey back in time to unifying all the 1100 00:58:03,960 --> 00:58:07,000 Speaker 1: forces and then forward again to breaking them up to 1101 00:58:07,080 --> 00:58:09,440 Speaker 1: explain the universe we know and love today. 1102 00:58:09,800 --> 00:58:12,200 Speaker 3: Thanks for joining us everyone, until next time. 1103 00:58:18,680 --> 00:58:21,080 Speaker 1: Thanks everybody for listening. Please go and do us a 1104 00:58:21,120 --> 00:58:24,360 Speaker 1: favor and rate the show on whatever podcast app you're using. 1105 00:58:24,440 --> 00:58:26,040 Speaker 1: It really helps people find us. 1106 00:58:26,560 --> 00:58:30,480 Speaker 3: Daniel and Kelly's Extraordinary Universe is edited by the amazing 1107 00:58:30,520 --> 00:58:31,240 Speaker 3: Matt Kesselman. 1108 00:58:31,480 --> 00:58:34,720 Speaker 1: He really is a wizard. You can also find us 1109 00:58:34,840 --> 00:58:39,880 Speaker 1: online on Blue Sky, Instagram and x D and K Universe. 1110 00:58:39,960 --> 00:58:41,200 Speaker 1: Come engage with us. 1111 00:58:41,440 --> 00:58:44,800 Speaker 3: You can email us at questions at Danielankelly dot org. 1112 00:58:44,880 --> 00:58:46,240 Speaker 3: We really do want to. 1113 00:58:46,160 --> 00:58:48,720 Speaker 1: Hear from you, and you can find our website www 1114 00:58:48,800 --> 00:58:52,520 Speaker 1: dot danieland Kelly dot org, where you'll also find an 1115 00:58:52,520 --> 00:58:56,120 Speaker 1: invitation to join our discord where everybody comes and talks 1116 00:58:56,160 --> 00:58:57,680 Speaker 1: about the amazing universe. 1117 00:58:58,040 --> 00:59:02,000 Speaker 3: And we also have the most amazing operators. This is 1118 00:59:02,000 --> 00:59:04,560 Speaker 3: an iHeart podcast. Thanks for joining us.