1 00:00:08,480 --> 00:00:11,119 Speaker 1: Hey, Daniel, do you ever get tired of answering questions 2 00:00:11,160 --> 00:00:11,920 Speaker 1: from listeners? 3 00:00:12,119 --> 00:00:14,560 Speaker 2: Not so far, But you know, ask me again in 4 00:00:14,560 --> 00:00:15,560 Speaker 2: another five years. 5 00:00:15,760 --> 00:00:17,200 Speaker 1: Oh, what's going to happen in five years? 6 00:00:18,880 --> 00:00:19,960 Speaker 2: I might have a different answer. 7 00:00:20,200 --> 00:00:22,480 Speaker 1: Some places you get the same questions over and over. 8 00:00:22,600 --> 00:00:24,680 Speaker 2: You know, there are a lot of common themes in 9 00:00:24,720 --> 00:00:25,880 Speaker 2: these questions, that's true. 10 00:00:25,920 --> 00:00:28,040 Speaker 1: And do you have like pre prepared answers ready to go? 11 00:00:28,160 --> 00:00:31,600 Speaker 2: You can't really do that because every question's a little 12 00:00:31,680 --> 00:00:34,240 Speaker 2: bit different. And for me, the fun part is figuring 13 00:00:34,240 --> 00:00:38,159 Speaker 2: out like what somebody misunderstood to lead to their confusion 14 00:00:38,240 --> 00:00:39,920 Speaker 2: and helping them unravel that. 15 00:00:41,080 --> 00:00:43,159 Speaker 1: So you kind of just like program an AI to 16 00:00:43,240 --> 00:00:45,839 Speaker 1: answer questions for you, kind of like they do now 17 00:00:45,840 --> 00:00:47,280 Speaker 1: with like customer service lines. 18 00:00:47,560 --> 00:00:49,960 Speaker 2: You could definitely program an AI to answer questions, but 19 00:00:50,000 --> 00:00:51,239 Speaker 2: it would generate nonsense. 20 00:00:51,560 --> 00:00:57,480 Speaker 1: Sometimes, isn't the answer nonsense? In physics, especially quantum mechanics, the. 21 00:00:57,480 --> 00:00:59,840 Speaker 2: Most amazing thing about the universe is that it doesn't 22 00:00:59,840 --> 00:01:02,960 Speaker 2: see aim to be nonsense. It seems to actually make sense. 23 00:01:03,200 --> 00:01:05,440 Speaker 1: So far, Maybe I'll ask you again in five years. 24 00:01:06,600 --> 00:01:08,959 Speaker 2: Maybe in five years you'll have replaced me with an AI. 25 00:01:09,760 --> 00:01:12,360 Speaker 1: Maybe in five years will all be replaced by AIS 26 00:01:12,760 --> 00:01:15,199 Speaker 1: and only AIS will be listening to this, but maybe 27 00:01:15,240 --> 00:01:15,840 Speaker 1: not I. 28 00:01:15,840 --> 00:01:31,640 Speaker 2: I Hi. 29 00:01:31,720 --> 00:01:34,120 Speaker 1: I'm Jorge, a me cartoonists and the author of Oliver's 30 00:01:34,200 --> 00:01:36,080 Speaker 1: Great Big Universe him. 31 00:01:36,240 --> 00:01:38,000 Speaker 2: You know, I'm a professor of physics and I do 32 00:01:38,080 --> 00:01:41,600 Speaker 2: experiments at CERN, and I don't think that I'm an AI. 33 00:01:42,720 --> 00:01:44,280 Speaker 1: But you could be. Are you saying. 34 00:01:46,880 --> 00:01:49,880 Speaker 2: We never know philosophically where our consciousness comes from. We 35 00:01:49,920 --> 00:01:51,480 Speaker 2: could all actually be AIS. 36 00:01:51,720 --> 00:01:54,160 Speaker 1: Yeah, we could. I guess there's several possibilities, right, Like 37 00:01:54,200 --> 00:01:55,920 Speaker 1: we could be in a simulation or something and we 38 00:01:55,920 --> 00:01:59,240 Speaker 1: could all be AIS. Or you know, if the people 39 00:01:59,520 --> 00:02:02,200 Speaker 1: were really Jesus, all right, then technically we are kind 40 00:02:02,200 --> 00:02:05,520 Speaker 1: of artificial intelligence because we were made by another intelligence. 41 00:02:05,640 --> 00:02:07,680 Speaker 2: Yeah, it certainly could be. Or we could all just 42 00:02:07,720 --> 00:02:10,760 Speaker 2: be cylons, you know, thinking we're humans, programmed to think 43 00:02:10,880 --> 00:02:14,960 Speaker 2: we are humans, but silicon underneath. Yeah. 44 00:02:15,120 --> 00:02:17,240 Speaker 1: On a TV show that sadly got canceled. 45 00:02:19,320 --> 00:02:20,240 Speaker 2: That was a great show. 46 00:02:20,280 --> 00:02:22,600 Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain 47 00:02:22,680 --> 00:02:25,359 Speaker 1: the Universe, a production of iHeartRadio. 48 00:02:24,720 --> 00:02:28,080 Speaker 2: In which we use our consciousness simulated or not, artificial 49 00:02:28,320 --> 00:02:31,560 Speaker 2: or not, to try to understand the nature of the universe. 50 00:02:31,680 --> 00:02:35,160 Speaker 2: Whether it's real or not, and whether our subjective experience 51 00:02:35,320 --> 00:02:38,519 Speaker 2: is organic or not. We think it's worthwhile to try 52 00:02:38,520 --> 00:02:41,280 Speaker 2: to understand what's out there, to try to make it 53 00:02:41,280 --> 00:02:45,240 Speaker 2: all work in our minds, to ask questions and seek answers, 54 00:02:45,320 --> 00:02:47,120 Speaker 2: and that's what this podcast is all about. 55 00:02:47,280 --> 00:02:49,880 Speaker 1: Yeah, sometimes I feel like by intelligence is simulated, Like 56 00:02:49,919 --> 00:02:51,320 Speaker 1: I'm just pretending to be intelligent. 57 00:02:52,919 --> 00:02:56,240 Speaker 2: What's the difference between being intelligent and effectively pretending? 58 00:02:56,480 --> 00:02:59,200 Speaker 1: Oh? Good point, that's an intelligent answer. And I don't 59 00:02:59,240 --> 00:03:01,280 Speaker 1: mean that in a fix. I mean that in an 60 00:03:01,400 --> 00:03:02,360 Speaker 1: unartificial sense. 61 00:03:04,080 --> 00:03:06,519 Speaker 2: Sometimes I feel like the most important function I serve 62 00:03:06,560 --> 00:03:10,120 Speaker 2: for my students is asking them dumb questions about their research. 63 00:03:10,520 --> 00:03:13,360 Speaker 2: And often I see it spark good ideas. They're like, 64 00:03:13,400 --> 00:03:15,360 Speaker 2: well that doesn't make any sense, but it gives me 65 00:03:15,400 --> 00:03:17,399 Speaker 2: a good idea about something I could do. 66 00:03:18,600 --> 00:03:21,360 Speaker 1: So you're incentivized to ask dumb questions. 67 00:03:21,560 --> 00:03:24,200 Speaker 2: I just simulate knowing what I'm doing, and somehow the 68 00:03:24,200 --> 00:03:25,880 Speaker 2: people around me get stuff done. 69 00:03:26,320 --> 00:03:28,760 Speaker 1: Sounds like you could program an AI to ask dumb 70 00:03:28,880 --> 00:03:31,079 Speaker 1: questions and then you don't have to do anything. 71 00:03:31,200 --> 00:03:33,600 Speaker 2: Yeah, exactly. I think often I could be replaced by 72 00:03:33,600 --> 00:03:36,920 Speaker 2: a cardboard cutout of myself. Just having students explain what 73 00:03:36,960 --> 00:03:39,760 Speaker 2: they're doing to me helps them understand what they're doing wrong. 74 00:03:39,960 --> 00:03:43,440 Speaker 1: Yeah, and it has pre program answers like or questions like, huh, 75 00:03:43,480 --> 00:03:45,880 Speaker 1: that's really interesting. Have you checked the error bars? 76 00:03:47,320 --> 00:03:48,920 Speaker 2: Are you sure about those assumptions? 77 00:03:49,040 --> 00:03:51,360 Speaker 1: That's it. Just have it on loop. People come in, 78 00:03:51,520 --> 00:03:54,800 Speaker 1: they press a button, You're in a Caribbean island doing nothing. 79 00:03:54,840 --> 00:03:56,560 Speaker 2: Yeah. Or they just pull a string behind me, or 80 00:03:56,600 --> 00:03:57,839 Speaker 2: I'm just like a stuffed Teddy bear. 81 00:03:58,720 --> 00:04:00,840 Speaker 1: Yeah, there you go. 82 00:04:00,960 --> 00:04:03,480 Speaker 2: Maybe we should actually make merch stuffed versions of us. 83 00:04:03,480 --> 00:04:05,400 Speaker 2: They pull the back of you and you go hmm, 84 00:04:05,720 --> 00:04:07,440 Speaker 2: and they pull the back of me and it goes chuckle. 85 00:04:07,640 --> 00:04:10,200 Speaker 1: Yeah. Perfect, And then someone could just repidate the entire 86 00:04:10,240 --> 00:04:11,200 Speaker 1: podcast without us. 87 00:04:11,240 --> 00:04:16,440 Speaker 2: There just stings. You could build a robot to pull 88 00:04:16,440 --> 00:04:17,520 Speaker 2: the strings and we'd be done. 89 00:04:18,320 --> 00:04:20,839 Speaker 1: Yeah. Oh man, but I guess you need someone to 90 00:04:21,080 --> 00:04:22,000 Speaker 1: press the record book. 91 00:04:23,760 --> 00:04:25,000 Speaker 2: I have students who can do that. 92 00:04:25,200 --> 00:04:28,200 Speaker 1: Perfect. But yeah, it is a pretty interesting and amazing universe. 93 00:04:28,200 --> 00:04:30,839 Speaker 1: Whether it's simulated or not, or whether we are simulated 94 00:04:30,960 --> 00:04:34,080 Speaker 1: or not, and whether we are artificial or not. We 95 00:04:34,160 --> 00:04:36,799 Speaker 1: have questions about what's going on in this universe, about 96 00:04:36,800 --> 00:04:37,560 Speaker 1: how it all works. 97 00:04:37,720 --> 00:04:40,760 Speaker 2: Scientists have questions and are busy doing experiments to try 98 00:04:40,800 --> 00:04:44,120 Speaker 2: to get answers. But we're not the only ones with questions. 99 00:04:44,200 --> 00:04:46,960 Speaker 2: Everybody out there asks questions about the nature of the 100 00:04:47,040 --> 00:04:49,440 Speaker 2: universe since the first people have looked up in the 101 00:04:49,520 --> 00:04:52,159 Speaker 2: night sky and wondered what all those twinkling lights were. 102 00:04:52,279 --> 00:04:55,320 Speaker 2: Being curious is just part of being human and looking 103 00:04:55,360 --> 00:04:58,200 Speaker 2: for answers is doing science, whether or not you're getting 104 00:04:58,200 --> 00:04:58,640 Speaker 2: paid for it. 105 00:04:58,680 --> 00:05:00,320 Speaker 1: Yeah, it's not just a job of sign this to 106 00:05:00,320 --> 00:05:03,040 Speaker 1: ask questions about geners. It's your job. It's everybody's job 107 00:05:03,040 --> 00:05:05,440 Speaker 1: to look at the cosmos and wonder why it's all 108 00:05:05,440 --> 00:05:06,599 Speaker 1: there and how it all works. 109 00:05:06,720 --> 00:05:08,960 Speaker 2: One of our goals on this podcast is to find 110 00:05:09,040 --> 00:05:12,440 Speaker 2: answers for you, but also to stimulate your questions, to 111 00:05:12,480 --> 00:05:15,360 Speaker 2: get you to think about the things you don't understand, 112 00:05:15,400 --> 00:05:17,280 Speaker 2: to hear what we're saying and then try to click 113 00:05:17,320 --> 00:05:20,480 Speaker 2: it together in your mind and when it doesn't quite fit. 114 00:05:20,600 --> 00:05:22,600 Speaker 2: We love if you reached out to us to ask 115 00:05:22,720 --> 00:05:26,279 Speaker 2: us your questions about the universe. We'll always answer them 116 00:05:26,320 --> 00:05:29,000 Speaker 2: to questions at Danielandjorge dot com. 117 00:05:29,160 --> 00:05:32,560 Speaker 1: Yeah, everybody has questions, the kids, adults, and everyone in between, 118 00:05:32,680 --> 00:05:34,800 Speaker 1: and sometimes we'd like to answer those questions here on 119 00:05:34,839 --> 00:05:35,359 Speaker 1: the podcast. 120 00:05:35,520 --> 00:05:37,680 Speaker 2: We absolutely do, so feel free to write to us 121 00:05:37,720 --> 00:05:40,640 Speaker 2: and ask us your questions. Sometimes I'll get a question 122 00:05:40,680 --> 00:05:42,600 Speaker 2: that I think, hmm, I bet other people want to 123 00:05:42,640 --> 00:05:44,520 Speaker 2: know the answer that, and so we'll answer it here 124 00:05:44,760 --> 00:05:45,599 Speaker 2: on the podcast. 125 00:05:45,680 --> 00:05:47,880 Speaker 1: Do you sometimes think, oh, nobody else wants to know 126 00:05:47,960 --> 00:05:50,640 Speaker 1: the answer to that? Do you have the opposite feeling? 127 00:05:50,760 --> 00:05:53,880 Speaker 2: I do sometimes get personal questions about people's life path 128 00:05:53,960 --> 00:05:57,480 Speaker 2: and stuff like that, and so yeah, that's individualized answers 129 00:05:57,480 --> 00:05:59,080 Speaker 2: that don't need to be on the podcast. 130 00:05:59,200 --> 00:06:01,160 Speaker 1: Do you get a quot question that it's like so 131 00:06:01,560 --> 00:06:05,560 Speaker 1: complicated you don't think anyone else would be interested. 132 00:06:05,680 --> 00:06:07,600 Speaker 2: I get a lot of people sending me their personal 133 00:06:07,680 --> 00:06:10,640 Speaker 2: theories of the universe, and I'm not sure anybody else 134 00:06:10,760 --> 00:06:13,240 Speaker 2: really wants to read those hundreds of pages written by 135 00:06:13,240 --> 00:06:14,240 Speaker 2: retired engineers. 136 00:06:14,839 --> 00:06:17,919 Speaker 1: But what if they're right? Oh? I see, But then 137 00:06:17,920 --> 00:06:21,480 Speaker 1: it becomes your theory, and then you want everyone to 138 00:06:21,520 --> 00:06:21,960 Speaker 1: read about it. 139 00:06:22,080 --> 00:06:24,240 Speaker 2: No. I read those theories and give them critiques, and 140 00:06:24,360 --> 00:06:26,360 Speaker 2: if there was something to it, then yeah, you'd hear 141 00:06:26,360 --> 00:06:27,000 Speaker 2: about it well. 142 00:06:27,000 --> 00:06:29,000 Speaker 1: As Daniel say, we'd like to answer questions here on 143 00:06:29,040 --> 00:06:31,520 Speaker 1: the podcast, and so on. Today's episode will be tackling 144 00:06:36,600 --> 00:06:42,279 Speaker 1: listener questions number forty five, Gravity and black holes. That's 145 00:06:42,320 --> 00:06:44,760 Speaker 1: the theme of the questions today, gravity and black holes. 146 00:06:44,880 --> 00:06:47,600 Speaker 2: Yeah, black holes and gravity seem to be on people's 147 00:06:47,640 --> 00:06:49,800 Speaker 2: minds the week that these questions came in. 148 00:06:50,000 --> 00:06:52,279 Speaker 1: Yeah, and so we have some great questions here about 149 00:06:53,200 --> 00:06:57,680 Speaker 1: famous physics experiments, the event horizons of black holes, and 150 00:06:57,760 --> 00:07:01,800 Speaker 1: what happens since the Big Bang. Pretty deep questions, deep 151 00:07:01,839 --> 00:07:03,920 Speaker 1: in time and space. So we'll just jump right in. 152 00:07:04,080 --> 00:07:06,520 Speaker 1: Our first question comes from Sean from Canada. 153 00:07:06,720 --> 00:07:09,120 Speaker 3: Hey, Daniel and Jorge, this is Sean calling from Canada. 154 00:07:09,720 --> 00:07:12,600 Speaker 3: I have a question about the observer effect. What would 155 00:07:12,640 --> 00:07:16,000 Speaker 3: happen if the observer was on the inside of the 156 00:07:16,040 --> 00:07:19,720 Speaker 3: event horizon of a black hole and the experiment being 157 00:07:19,800 --> 00:07:22,880 Speaker 3: observed was on the outside of the event horizon of 158 00:07:22,920 --> 00:07:27,200 Speaker 3: a black hole? Would it know that it's being observed? 159 00:07:27,360 --> 00:07:31,040 Speaker 3: Would the waves collapse and all that stuff? 160 00:07:31,240 --> 00:07:31,920 Speaker 2: Yeah, let me know. 161 00:07:32,120 --> 00:07:35,640 Speaker 1: Thanks, interesting question. I guess the gist of it is 162 00:07:35,640 --> 00:07:37,840 Speaker 1: that what happens if you're inside of a black hole 163 00:07:38,000 --> 00:07:40,240 Speaker 1: can't tell what's going on outside of the black hole. 164 00:07:40,360 --> 00:07:42,320 Speaker 2: Yeah, there's a lot of really interesting stuff going on 165 00:07:42,400 --> 00:07:45,520 Speaker 2: in this question. It's about black holes, it's about quantum mechanics, 166 00:07:45,680 --> 00:07:48,520 Speaker 2: it's about all that kind of stuff. Of course, inside 167 00:07:48,560 --> 00:07:51,080 Speaker 2: a black hole, you can see things that are happening 168 00:07:51,160 --> 00:07:54,040 Speaker 2: outside a black hole, right. A black hole is where 169 00:07:54,080 --> 00:07:58,160 Speaker 2: information cannot escape from, but new information can always arrive, 170 00:07:58,640 --> 00:08:00,960 Speaker 2: Like photons can fall in do black holes, and if 171 00:08:00,960 --> 00:08:03,520 Speaker 2: you were inside a black hole, those photons could still 172 00:08:03,520 --> 00:08:06,280 Speaker 2: reach you. So from within a black hole, you can 173 00:08:06,480 --> 00:08:09,320 Speaker 2: observe things happening in the outside of the universe. But 174 00:08:09,400 --> 00:08:12,400 Speaker 2: I love this question because it touches on this complicated 175 00:08:12,480 --> 00:08:16,960 Speaker 2: quantum mechanical issue of observing things changing them right. Often 176 00:08:17,000 --> 00:08:20,320 Speaker 2: in quantum mechanics we say that observation changes an experiment, 177 00:08:20,480 --> 00:08:23,600 Speaker 2: And he's wondering, if you're doing that observation while you're 178 00:08:23,680 --> 00:08:26,520 Speaker 2: inside a black hole, can you change an experiment that's 179 00:08:26,560 --> 00:08:27,880 Speaker 2: outside a black hole. 180 00:08:28,760 --> 00:08:32,800 Speaker 1: Because I guess in quantum mechanics, once you observe something 181 00:08:33,000 --> 00:08:35,600 Speaker 1: it like, it changes the wave function of it right exactly. 182 00:08:35,640 --> 00:08:37,920 Speaker 2: And this is something in quantum mechanics that's not very 183 00:08:38,000 --> 00:08:40,719 Speaker 2: well understood. So often when you push the boundaries and 184 00:08:40,760 --> 00:08:43,080 Speaker 2: come up with crazy thought experiments, the answer is we 185 00:08:43,120 --> 00:08:46,679 Speaker 2: don't know or we have no idea because actually our 186 00:08:46,720 --> 00:08:49,760 Speaker 2: theory quantum mechanics doesn't make any sense, so it's probably 187 00:08:49,760 --> 00:08:52,240 Speaker 2: important to like sum up what is the observer effect 188 00:08:52,280 --> 00:08:54,280 Speaker 2: in quantum mechanics what we're talking about here. 189 00:08:55,040 --> 00:08:57,320 Speaker 1: But I guess maybe I have many more basic questions 190 00:08:57,360 --> 00:08:59,959 Speaker 1: about the setup here. So like the observer, you are 191 00:09:00,120 --> 00:09:02,360 Speaker 1: inside the black hole, and this is I guess, assuming 192 00:09:02,400 --> 00:09:04,160 Speaker 1: you survive going into the black hole. 193 00:09:04,000 --> 00:09:06,480 Speaker 2: Right, yeah, I assume. I assume you survive. If you're 194 00:09:06,520 --> 00:09:08,199 Speaker 2: observing the experiment. 195 00:09:07,920 --> 00:09:09,720 Speaker 1: Like you have a camera and you take it inside 196 00:09:09,720 --> 00:09:12,080 Speaker 1: of the black hole and you somehow survive, you would 197 00:09:12,120 --> 00:09:14,720 Speaker 1: still be getting information from outside the black hole, but 198 00:09:14,760 --> 00:09:17,160 Speaker 1: you wouldn't, I guess. See, like the whole universe, like 199 00:09:17,160 --> 00:09:19,400 Speaker 1: I think we've talked about this before, the whole universe 200 00:09:19,440 --> 00:09:21,439 Speaker 1: would look like one pinpoint to you. 201 00:09:21,600 --> 00:09:24,079 Speaker 2: That's right, All light that arrives on the black hole 202 00:09:24,320 --> 00:09:27,600 Speaker 2: would arrive to you and just one point. So like 203 00:09:27,640 --> 00:09:30,600 Speaker 2: the entire event horizon would be collapsed to a single 204 00:09:30,720 --> 00:09:33,960 Speaker 2: point in your vision. The rest every other direction from 205 00:09:33,960 --> 00:09:37,320 Speaker 2: your perspective would be towards the singularity. Because remember that 206 00:09:37,400 --> 00:09:42,080 Speaker 2: black holes are curvatures of space time, and so changing 207 00:09:42,080 --> 00:09:45,200 Speaker 2: the way space is organized inside the black hole. 208 00:09:45,080 --> 00:09:47,160 Speaker 1: Okay, So now the scenario is that there's maybe like 209 00:09:47,200 --> 00:09:50,600 Speaker 1: an electron just outside the black hole, and it's about 210 00:09:50,640 --> 00:09:52,640 Speaker 1: to veer to the right or to the left depending 211 00:09:52,679 --> 00:09:55,400 Speaker 1: on some magnetic field right because it has some quantum 212 00:09:55,480 --> 00:09:58,040 Speaker 1: uncertainty about that. And then the question is could you 213 00:09:58,080 --> 00:10:02,040 Speaker 1: see that, Like, could the photon from that electron reach you? 214 00:10:02,080 --> 00:10:02,760 Speaker 1: Would it reach you? 215 00:10:02,960 --> 00:10:05,800 Speaker 2: So a photon from that electron definitely could reach you. 216 00:10:05,840 --> 00:10:08,000 Speaker 2: If the electron gives off a photon that can fall 217 00:10:08,000 --> 00:10:10,360 Speaker 2: in the black hole, and then it can reach you 218 00:10:10,520 --> 00:10:13,240 Speaker 2: inside the black hole absolutely. 219 00:10:12,679 --> 00:10:15,600 Speaker 1: What about like time, doesn't time slow down at the 220 00:10:15,640 --> 00:10:17,760 Speaker 1: surface of a black hole, or doesn't it stand still? 221 00:10:17,880 --> 00:10:20,560 Speaker 2: So time does get slowed down by gravity. Places that 222 00:10:20,600 --> 00:10:24,240 Speaker 2: have strong curvature feel time going more slowly. So for example, 223 00:10:24,280 --> 00:10:26,040 Speaker 2: if you're near a black hole and you're looking at 224 00:10:26,080 --> 00:10:28,800 Speaker 2: the rest of the universe, your time is going more slowly. 225 00:10:28,800 --> 00:10:30,760 Speaker 2: You see the rest of the universe going more quickly. 226 00:10:31,200 --> 00:10:33,559 Speaker 2: Or if you're watching somebody fall into a black hole, 227 00:10:33,760 --> 00:10:36,720 Speaker 2: you see their time slow down. So from the outside 228 00:10:36,720 --> 00:10:39,400 Speaker 2: you can't actually see somebody fall into a black hole. 229 00:10:39,440 --> 00:10:41,679 Speaker 2: You're right, if time slows down so much as they 230 00:10:41,679 --> 00:10:44,480 Speaker 2: approach the event horizon, that it's not until, like time 231 00:10:44,520 --> 00:10:48,400 Speaker 2: equals infinity, that they actually fall in from your perspective. 232 00:10:48,600 --> 00:10:51,800 Speaker 2: But if you're the person falling into the event horizon, 233 00:10:52,240 --> 00:10:54,400 Speaker 2: then you just fall past the event horizon. You don't 234 00:10:54,440 --> 00:10:55,360 Speaker 2: notice these effects. 235 00:10:55,880 --> 00:10:58,360 Speaker 1: The electron would just fly right in from your perspective 236 00:10:58,400 --> 00:10:58,920 Speaker 1: inside the. 237 00:10:58,840 --> 00:11:00,840 Speaker 2: Black hole, inside the black hole exactly, but. 238 00:11:00,720 --> 00:11:03,480 Speaker 1: Really outside of the black hole, it wouldn't happen for infinity. 239 00:11:03,600 --> 00:11:05,720 Speaker 2: From the point of view of a distant observer watching 240 00:11:05,760 --> 00:11:08,440 Speaker 2: you fall in, it wouldn't happen until time egals infinity, 241 00:11:08,840 --> 00:11:11,680 Speaker 2: or until something else falls in the black hole and 242 00:11:11,800 --> 00:11:14,400 Speaker 2: grows it so that it encompasses you. That's the reason 243 00:11:14,400 --> 00:11:17,160 Speaker 2: that like real black holes in the universe can actually grow, 244 00:11:17,640 --> 00:11:19,640 Speaker 2: that they don't have to wait until time equals infinity 245 00:11:19,679 --> 00:11:21,600 Speaker 2: for things to fall in, because there's a whole series 246 00:11:21,640 --> 00:11:24,880 Speaker 2: of things falling in. Each one grows the event horizon 247 00:11:25,000 --> 00:11:26,000 Speaker 2: for the previous one. 248 00:11:26,520 --> 00:11:29,200 Speaker 1: Okay, so you can get information from inside the black hole, 249 00:11:29,600 --> 00:11:31,760 Speaker 1: and I guess you're not really watching the electron. You're 250 00:11:31,800 --> 00:11:34,520 Speaker 1: just watching whether it veers to the rider to the left, right, 251 00:11:34,640 --> 00:11:37,240 Speaker 1: something to texts the electron going right or left or something. 252 00:11:37,320 --> 00:11:40,040 Speaker 2: Yeah, I think the setupiece interested in is like an 253 00:11:40,080 --> 00:11:42,679 Speaker 2: electron is in a superposition of two possible states, like 254 00:11:42,720 --> 00:11:44,800 Speaker 2: does it go left or right? And somehow you maybe 255 00:11:44,880 --> 00:11:47,720 Speaker 2: use a photon to detect left versus right, and that 256 00:11:47,720 --> 00:11:51,400 Speaker 2: photon falls into the black hole. And he's wondering if 257 00:11:51,559 --> 00:11:55,480 Speaker 2: observing that photon inside the black hole collapses the way 258 00:11:55,559 --> 00:11:57,959 Speaker 2: functioning the experiment outside the black. 259 00:11:57,679 --> 00:12:00,959 Speaker 1: Hole right, because I guess since you're inside the black hole, 260 00:12:01,080 --> 00:12:04,640 Speaker 1: there's like no way for the electron to know whether 261 00:12:04,679 --> 00:12:06,320 Speaker 1: you saw it or not exactly. 262 00:12:06,360 --> 00:12:09,320 Speaker 2: That's where this cool quantum mechanics black hole paradox comes in, 263 00:12:09,520 --> 00:12:11,000 Speaker 2: because if you take away the black hole, we had 264 00:12:11,040 --> 00:12:13,400 Speaker 2: the sort of classic observer effect that the electron can 265 00:12:13,520 --> 00:12:17,360 Speaker 2: still be fifty percent chance left, fifty percent chance right 266 00:12:17,800 --> 00:12:20,600 Speaker 2: until its wave function is collapsed. When does the wave 267 00:12:20,600 --> 00:12:23,520 Speaker 2: function collapse? Well, nobody really knows the answer to that, 268 00:12:23,840 --> 00:12:28,360 Speaker 2: but one ridiculous but standard description or quantum mechanics says 269 00:12:28,520 --> 00:12:32,000 Speaker 2: that the electron's wave function is collapsed when is observed 270 00:12:32,040 --> 00:12:35,280 Speaker 2: by a classical object like a person or a big 271 00:12:35,320 --> 00:12:38,360 Speaker 2: detector or something. So the photon can bounce off of 272 00:12:38,360 --> 00:12:41,280 Speaker 2: the electron without collapsing its wave function because it's still 273 00:12:41,280 --> 00:12:43,880 Speaker 2: a quantum object. But then when that photon carrying that 274 00:12:43,960 --> 00:12:47,240 Speaker 2: information hits a screen or a detector or an eyeball 275 00:12:47,360 --> 00:12:50,079 Speaker 2: or something like that, a classical object, it collapses the 276 00:12:50,120 --> 00:12:53,600 Speaker 2: whole wave function. And that's when the electron decided, okay 277 00:12:53,679 --> 00:12:55,280 Speaker 2: I went left or okay I went right. 278 00:12:55,720 --> 00:12:58,240 Speaker 1: But does it collapse only for the observer or for 279 00:12:58,320 --> 00:13:01,240 Speaker 1: the entire universe? If if you observe it, but I 280 00:13:01,280 --> 00:13:03,440 Speaker 1: don't know what you observe, is it still a quantum 281 00:13:03,520 --> 00:13:04,080 Speaker 1: object to me? 282 00:13:04,320 --> 00:13:07,360 Speaker 2: Oh? Great question? And the answer to that depends on 283 00:13:07,400 --> 00:13:12,400 Speaker 2: your quantum mechanics philosophy. So in standard quantum mechanics Copenhagen interpretation, 284 00:13:12,679 --> 00:13:16,680 Speaker 2: it collapses for everybody, and it collapses instantly across space 285 00:13:16,720 --> 00:13:19,880 Speaker 2: and time. Those two objects are entangled. The photon and 286 00:13:19,920 --> 00:13:23,360 Speaker 2: the electron are quantum mechanically entangled, meaning that they share 287 00:13:23,400 --> 00:13:25,760 Speaker 2: a fate. They're connected to each other. If the electron 288 00:13:25,840 --> 00:13:27,559 Speaker 2: goes left, then the photon looks a certain way, and 289 00:13:27,600 --> 00:13:30,480 Speaker 2: if electron goes right, the photon looks another way. So 290 00:13:30,520 --> 00:13:33,640 Speaker 2: in your standard interpretation, as soon as you observe the photon, 291 00:13:33,920 --> 00:13:37,720 Speaker 2: that collapses the electron for everybody. But in other interpretations, 292 00:13:37,720 --> 00:13:41,960 Speaker 2: to quantum mechanics like Carlo Ravelli's relational quantum mechanics. Then 293 00:13:42,000 --> 00:13:45,079 Speaker 2: it only collapses for the person doing the observation. One 294 00:13:45,160 --> 00:13:47,760 Speaker 2: person can collapse it for themselves, somebody else could have 295 00:13:47,760 --> 00:13:50,280 Speaker 2: it be uncollapsed, and a third person can collapse it 296 00:13:50,360 --> 00:13:53,240 Speaker 2: in another way. So there's different theories of quantum mechanics 297 00:13:53,320 --> 00:13:55,760 Speaker 2: in the standard one that people typically think about and 298 00:13:55,800 --> 00:13:58,240 Speaker 2: we complain about a lot because it doesn't make much sense. 299 00:13:58,600 --> 00:13:59,959 Speaker 2: It's collapsed for everybody. 300 00:14:00,080 --> 00:14:02,360 Speaker 1: It also sort of depends on the idea of short 301 00:14:02,400 --> 00:14:04,800 Speaker 1: Anger's box, right, doesn't it? Like if I wrap a 302 00:14:04,840 --> 00:14:07,679 Speaker 1: box or on you the observer and the electron, like, 303 00:14:07,760 --> 00:14:10,080 Speaker 1: it's still a quantum object to me, no matter whose 304 00:14:10,120 --> 00:14:12,640 Speaker 1: interpretation I think about, does it the cat is both 305 00:14:12,679 --> 00:14:14,400 Speaker 1: alive and dad and you saw it and not saw 306 00:14:14,400 --> 00:14:15,080 Speaker 1: it at the same time. 307 00:14:15,160 --> 00:14:18,120 Speaker 2: Yeah, that is the paradox rate by Schrodinger's box, that 308 00:14:18,200 --> 00:14:21,160 Speaker 2: things can be unobserved but still be classical. So in 309 00:14:21,200 --> 00:14:25,200 Speaker 2: the standard Copenhagen interpretation we say classical objects collapse the 310 00:14:25,240 --> 00:14:27,880 Speaker 2: wave function and quantum objects do not. The problem with 311 00:14:27,880 --> 00:14:30,520 Speaker 2: the standard quantum mechanics is that there's no definition of 312 00:14:30,520 --> 00:14:33,080 Speaker 2: what's a classical and what's a quantum object, so it's 313 00:14:33,120 --> 00:14:36,920 Speaker 2: sort of a useless distinction. But in the standard interpretation 314 00:14:37,480 --> 00:14:40,200 Speaker 2: then you would still become collapse the wave function because 315 00:14:40,200 --> 00:14:43,480 Speaker 2: you'd be a classical object and your observation collapses it. 316 00:14:43,520 --> 00:14:45,560 Speaker 2: Even if I don't know what you've seen before. You're 317 00:14:45,600 --> 00:14:48,080 Speaker 2: not a quantum object, so you can't be in a superposition. 318 00:14:48,200 --> 00:14:50,400 Speaker 1: Okay, so that this is an extra twist to it. Now, 319 00:14:50,480 --> 00:14:52,440 Speaker 1: let's say that you're the observer and you're inside of 320 00:14:52,440 --> 00:14:55,120 Speaker 1: a black hole and you saw the electron go right 321 00:14:55,200 --> 00:14:57,920 Speaker 1: or left. I think Sean is asking, how does that 322 00:14:58,600 --> 00:15:01,320 Speaker 1: affect things that the wavefund collapse for the electron or 323 00:15:01,400 --> 00:15:03,760 Speaker 1: is it still unknown for the rest of the universe. 324 00:15:03,960 --> 00:15:07,200 Speaker 2: This is a really great and very very difficult question, 325 00:15:07,440 --> 00:15:09,160 Speaker 2: and before we answer it, I want to compare it 326 00:15:09,200 --> 00:15:12,720 Speaker 2: to a similar complicated question, which is just about entangled 327 00:15:12,720 --> 00:15:15,840 Speaker 2: objects that are really far apart right. A similar question 328 00:15:15,880 --> 00:15:18,160 Speaker 2: you might ask, is, well, well, if the photon is 329 00:15:18,200 --> 00:15:21,520 Speaker 2: really far away from the electron when it's observed, how 330 00:15:21,560 --> 00:15:25,280 Speaker 2: does the electron know to collapse? If the photon flies 331 00:15:25,360 --> 00:15:28,560 Speaker 2: for a thousand light years before it gets observed, how 332 00:15:28,560 --> 00:15:32,680 Speaker 2: does the electron then collapse instantly across time? These questions 333 00:15:32,720 --> 00:15:35,280 Speaker 2: are related because they have to do with apparently sending 334 00:15:35,320 --> 00:15:39,080 Speaker 2: impossible information. And this is a classic question in quantum 335 00:15:39,080 --> 00:15:41,920 Speaker 2: mechanics theory, right, And this is the paradox posed by 336 00:15:42,000 --> 00:15:44,720 Speaker 2: Einstein decades and decades ago when he can plain the 337 00:15:44,800 --> 00:15:47,920 Speaker 2: quantum mechanics makes no sense because it requires things to 338 00:15:48,000 --> 00:15:52,560 Speaker 2: violate special relativity to collapse instantly across time. Things outside 339 00:15:52,560 --> 00:15:56,120 Speaker 2: of each other's light cones somehow, causing each other to change. 340 00:15:56,720 --> 00:15:59,360 Speaker 1: So, in the case of it entangled quantum paricles, the 341 00:15:59,440 --> 00:16:01,840 Speaker 1: answer that but it does travel faster than light in 342 00:16:01,880 --> 00:16:05,440 Speaker 1: a way, right, Like, once you collapse one half of 343 00:16:05,480 --> 00:16:08,080 Speaker 1: it a few light years away, it sort of instantly 344 00:16:08,280 --> 00:16:10,200 Speaker 1: changes what you have in front of you exactly. 345 00:16:10,240 --> 00:16:13,360 Speaker 2: And there's a really crucial subtlety here. You're totally right 346 00:16:13,400 --> 00:16:16,840 Speaker 2: that the collapse happens instantaneously across space and time. So 347 00:16:16,920 --> 00:16:19,720 Speaker 2: quantum mechanics is what we call non local. And that's 348 00:16:19,760 --> 00:16:22,080 Speaker 2: because the wave function is broad. It doesn't just exist 349 00:16:22,160 --> 00:16:24,840 Speaker 2: in one place. Don't think of it like one particle 350 00:16:24,960 --> 00:16:28,080 Speaker 2: doing something to the other particle. It's one big quantum state, 351 00:16:28,120 --> 00:16:32,080 Speaker 2: and you collapse it anywhere. It collapses everywhere simultaneously. That 352 00:16:32,160 --> 00:16:35,360 Speaker 2: does happen instantaneously across space and time. But and this 353 00:16:35,440 --> 00:16:38,840 Speaker 2: is the crucial nuance, it doesn't send any information. So 354 00:16:38,960 --> 00:16:42,000 Speaker 2: collapsing the wave function with a photon really really far 355 00:16:42,040 --> 00:16:45,840 Speaker 2: apart doesn't send information to the electron. You can't use 356 00:16:45,880 --> 00:16:48,640 Speaker 2: it to like send signals faster than the speed of light. 357 00:16:48,880 --> 00:16:51,560 Speaker 2: Though a lot of people imagine that quantum mechanics entanglement 358 00:16:51,840 --> 00:16:55,440 Speaker 2: can do that, you can't actually send information. Just collapses 359 00:16:55,440 --> 00:16:58,440 Speaker 2: the whole wave function simultaneously. It's not a mechanism for 360 00:16:58,560 --> 00:16:59,840 Speaker 2: information transmission. 361 00:17:00,080 --> 00:17:01,840 Speaker 1: I see. I think what you're saying is that, like 362 00:17:01,880 --> 00:17:04,840 Speaker 1: there's no rule to how big a quantum system can 363 00:17:04,880 --> 00:17:08,240 Speaker 1: be or how far apart its parts can be. So 364 00:17:08,280 --> 00:17:09,920 Speaker 1: like even a half, if I have one half here 365 00:17:09,960 --> 00:17:12,120 Speaker 1: and another half, you know, millions of lighters a way, 366 00:17:12,200 --> 00:17:14,520 Speaker 1: it's just still one quantum system. There's no rule in 367 00:17:14,560 --> 00:17:16,480 Speaker 1: quantum mechanics that says, oh, no, you're too far apart. 368 00:17:16,520 --> 00:17:18,920 Speaker 1: Now you're two separate quantum systems. You're actually like still 369 00:17:18,920 --> 00:17:20,640 Speaker 1: the same system exactly. 370 00:17:20,680 --> 00:17:24,840 Speaker 2: And quantum mechanics explicitly is non local. Stuff can happen 371 00:17:24,960 --> 00:17:27,960 Speaker 2: coordinated across space and time. It doesn't have to be 372 00:17:28,080 --> 00:17:30,600 Speaker 2: like this thing bumps into that thing which is right 373 00:17:30,680 --> 00:17:33,399 Speaker 2: next to it. Very weird property of quantum mechanics that 374 00:17:33,440 --> 00:17:35,280 Speaker 2: we really don't fully understand. 375 00:17:35,760 --> 00:17:38,040 Speaker 1: Okay, and so now the question is, what if half 376 00:17:38,080 --> 00:17:40,320 Speaker 1: of my system is inside of a black hole? Is 377 00:17:40,359 --> 00:17:41,679 Speaker 1: it still one system? 378 00:17:41,840 --> 00:17:44,840 Speaker 2: Great question, and the answer depends on your theory of 379 00:17:44,960 --> 00:17:47,520 Speaker 2: quantum gravity, because now this is a question that involves 380 00:17:47,600 --> 00:17:50,760 Speaker 2: quantum mechanics. We're talking about quantum particles and wave functions, 381 00:17:51,160 --> 00:17:55,240 Speaker 2: and it involves event horizons, so gravitational effects. And the 382 00:17:55,280 --> 00:17:57,959 Speaker 2: truth is we don't know how to marry those two things. 383 00:17:58,320 --> 00:18:01,160 Speaker 2: So I'm sorry, Sean, you're asking a question we don't 384 00:18:01,200 --> 00:18:03,560 Speaker 2: really know the answer to because we don't have a 385 00:18:03,600 --> 00:18:05,440 Speaker 2: theory of quantum gravity. 386 00:18:05,160 --> 00:18:08,440 Speaker 1: Meaning like we don't know how like if you distorted 387 00:18:08,440 --> 00:18:10,400 Speaker 1: gravity a lot, like in a black hole, you don't 388 00:18:10,400 --> 00:18:13,320 Speaker 1: know how it affects this idea of like a quantum 389 00:18:13,359 --> 00:18:16,280 Speaker 1: system being the two halves even though they're far apart exactly. 390 00:18:16,320 --> 00:18:17,720 Speaker 1: We just don't know it might affect it or it 391 00:18:17,800 --> 00:18:18,919 Speaker 1: might not affect it exactly. 392 00:18:19,000 --> 00:18:21,600 Speaker 2: We don't know if gravity collapses wave functions or not, 393 00:18:22,040 --> 00:18:25,159 Speaker 2: or if gravity is fundamentally quantum mechanical and allows things 394 00:18:25,200 --> 00:18:28,679 Speaker 2: to be in superpositions even as they cross event horizons. 395 00:18:28,800 --> 00:18:31,440 Speaker 2: We don't have the answer to that, but I can 396 00:18:31,480 --> 00:18:34,600 Speaker 2: speculate an analogy to the other scenario where you have 397 00:18:34,600 --> 00:18:38,320 Speaker 2: two quantum particles really far apart, basically outside of each 398 00:18:38,320 --> 00:18:41,280 Speaker 2: other's light cones, which is sort of like being outside 399 00:18:41,320 --> 00:18:44,280 Speaker 2: of each other's event horizons. There's still the wave function 400 00:18:44,400 --> 00:18:47,840 Speaker 2: does collapse, but no information is transmitted. So I suspect 401 00:18:47,840 --> 00:18:50,520 Speaker 2: that what happens here is that if you observe the 402 00:18:50,520 --> 00:18:54,359 Speaker 2: photon inside the black hole, it does collapse the wave 403 00:18:54,400 --> 00:18:57,440 Speaker 2: function of the electron outside the black hole, but without 404 00:18:57,480 --> 00:19:01,520 Speaker 2: transmitting any information and so not breaking that rule of 405 00:19:01,560 --> 00:19:02,240 Speaker 2: black holes. 406 00:19:02,840 --> 00:19:06,200 Speaker 1: WHOA Does that mean you could now communicate from inside 407 00:19:06,200 --> 00:19:08,320 Speaker 1: of a black hole to the outside of a black hole. 408 00:19:08,480 --> 00:19:10,800 Speaker 2: No. In the same way that you can't use quantum 409 00:19:10,920 --> 00:19:14,960 Speaker 2: entangled particle collapse to send information, you also can't send 410 00:19:15,040 --> 00:19:18,920 Speaker 2: information from inside and event horizon using the collapse of 411 00:19:18,960 --> 00:19:22,840 Speaker 2: a quantum object across that event horizon. That's the analogy. 412 00:19:23,440 --> 00:19:26,160 Speaker 1: So I wonder for like, practically speaking, you didn't really 413 00:19:26,200 --> 00:19:28,399 Speaker 1: collapse it because you're inside of a black hole and 414 00:19:28,440 --> 00:19:31,400 Speaker 1: nobody will ever know what you saw, So pretty much 415 00:19:31,400 --> 00:19:34,080 Speaker 1: in the rest of the universe. The half that's outside 416 00:19:34,160 --> 00:19:36,040 Speaker 1: is still quantum unknown. 417 00:19:36,160 --> 00:19:39,200 Speaker 2: Yeah, that's very insightful because the reason you can't send 418 00:19:39,280 --> 00:19:43,199 Speaker 2: information across quantum particles faster than light is that you 419 00:19:43,240 --> 00:19:45,760 Speaker 2: can't know whether it's collapsed. Like if I have a 420 00:19:45,800 --> 00:19:48,600 Speaker 2: quantum particle and you have a quantum particle and they're entangled, 421 00:19:48,880 --> 00:19:51,800 Speaker 2: I can measure mine, which would collapse yours if you 422 00:19:51,840 --> 00:19:53,840 Speaker 2: haven't already measured it, But you can't tell if I've 423 00:19:53,840 --> 00:19:55,840 Speaker 2: collapsed at All you can do is measure your particle 424 00:19:55,840 --> 00:19:57,600 Speaker 2: and get like spin up or spin down, or left 425 00:19:57,680 --> 00:20:00,000 Speaker 2: or right. You can never tell that I've collapsed it. 426 00:20:00,320 --> 00:20:03,840 Speaker 2: That information doesn't get transmitted. And so in the same way, 427 00:20:03,880 --> 00:20:06,960 Speaker 2: if somebody observes that photon inside the event horizon, somebody 428 00:20:07,040 --> 00:20:10,120 Speaker 2: else looking at the electron can't tell whether the electrons 429 00:20:10,160 --> 00:20:11,679 Speaker 2: wave function has been collapsed or not. 430 00:20:11,880 --> 00:20:14,560 Speaker 1: Okay, So then the answer for Sean is that we 431 00:20:14,680 --> 00:20:18,080 Speaker 1: have no idea. That's just a comment answer we give 432 00:20:18,080 --> 00:20:21,600 Speaker 1: you on the podcast, because nobody knows how gravity or 433 00:20:21,600 --> 00:20:25,200 Speaker 1: extreme gravity like black holes effects quantum mechanics and quantum 434 00:20:25,240 --> 00:20:27,679 Speaker 1: systems and wave collapse. But our best guess here on 435 00:20:27,720 --> 00:20:30,320 Speaker 1: the podcast is that it probably does collapse it, but 436 00:20:30,480 --> 00:20:32,560 Speaker 1: maybe it doesn't matter, so it doesn't really collapse it. 437 00:20:33,200 --> 00:20:34,920 Speaker 2: Yeah, that's a great summary. 438 00:20:35,040 --> 00:20:37,639 Speaker 1: Well, let's get to our other questions here today about 439 00:20:37,680 --> 00:20:41,520 Speaker 1: black holes and about the big Dang and magnetic fields. 440 00:20:41,720 --> 00:20:43,639 Speaker 1: So let's get to those, but first let's take a 441 00:20:43,760 --> 00:20:59,240 Speaker 1: quick break. Right. We're taking listener questions here today and 442 00:20:59,560 --> 00:21:02,280 Speaker 1: at least trying to answer them. Although sometimes the answer 443 00:21:02,440 --> 00:21:03,680 Speaker 1: is we don't nobody knows. 444 00:21:03,760 --> 00:21:06,080 Speaker 2: Sometimes the answer is, great question, I wish I knew 445 00:21:06,119 --> 00:21:06,560 Speaker 2: the answer. 446 00:21:07,440 --> 00:21:09,679 Speaker 1: Yeah, if you have the answer, write it to us 447 00:21:09,720 --> 00:21:12,240 Speaker 1: in one hundred page summary and then Daniel will read 448 00:21:12,240 --> 00:21:13,000 Speaker 1: it and let you know. 449 00:21:13,359 --> 00:21:16,160 Speaker 2: That's right. Really, the answer some of these questions requires 450 00:21:16,240 --> 00:21:19,119 Speaker 2: us to develop theories of quantum gravity, and to figure 451 00:21:19,119 --> 00:21:21,000 Speaker 2: out how to develop those theories, we want to look 452 00:21:21,000 --> 00:21:24,240 Speaker 2: inside black holes, which is impossible, so we're a little 453 00:21:24,240 --> 00:21:25,359 Speaker 2: bit stuck sometimes. 454 00:21:25,440 --> 00:21:27,159 Speaker 1: Well, you can look inside of a black hole, just 455 00:21:27,160 --> 00:21:28,800 Speaker 1: can't tell anyone what you saw. 456 00:21:30,240 --> 00:21:32,760 Speaker 2: Yeah, that's right. That physicist who fell into a black 457 00:21:32,800 --> 00:21:36,080 Speaker 2: hole knows the answers, just can't get any awards for it. 458 00:21:36,520 --> 00:21:40,359 Speaker 1: Yeah, that physicists solved everything. Let's throw a Nobel Prize 459 00:21:40,359 --> 00:21:46,240 Speaker 1: medal inside the black hole for them that million dollars 460 00:21:46,640 --> 00:21:49,679 Speaker 1: also or million coroner. I'm sure they can find a 461 00:21:49,680 --> 00:21:51,320 Speaker 1: good use for it in there. All right. So our 462 00:21:51,320 --> 00:21:54,760 Speaker 1: second question comes from Ryan, who lives in northern Virginia. 463 00:21:54,800 --> 00:21:57,399 Speaker 4: Hello, Daniel and Hore. My name is Ryan and I 464 00:21:57,480 --> 00:21:59,679 Speaker 4: live in northern Virginia. I have a question for you 465 00:21:59,720 --> 00:22:03,400 Speaker 4: today about black holes, more specifically about their magnetic fields. 466 00:22:03,800 --> 00:22:06,920 Speaker 4: If the Earth's magnetic field comes from its liquid outer core, 467 00:22:07,320 --> 00:22:10,879 Speaker 4: where does a black holes magnetic field come from? Considering 468 00:22:10,880 --> 00:22:13,840 Speaker 4: there's no liquid core in the black hole and nothing 469 00:22:13,920 --> 00:22:16,080 Speaker 4: is supposed to be able to escape the event horizon, 470 00:22:16,560 --> 00:22:18,800 Speaker 4: I'm left to guess that the accretion disk is the 471 00:22:18,840 --> 00:22:21,880 Speaker 4: big driver of the magnetic field. But that's just a guess. 472 00:22:22,280 --> 00:22:24,560 Speaker 4: Thanks for considering my question, Love the show. 473 00:22:24,840 --> 00:22:27,399 Speaker 1: Awesome great question, Ryan. You know I don't know the 474 00:22:27,440 --> 00:22:30,119 Speaker 1: answer here, and I'm gonna guess maybe the answer is again, 475 00:22:30,359 --> 00:22:32,920 Speaker 1: we don't know because it deals with black holes. 476 00:22:33,400 --> 00:22:36,400 Speaker 2: No, this one I think we do know the answer to. Actually, well, 477 00:22:37,320 --> 00:22:40,159 Speaker 2: I know physics knows something, all right. 478 00:22:40,200 --> 00:22:43,200 Speaker 1: Well, let's see. Ryan's question is where does a black 479 00:22:43,240 --> 00:22:46,800 Speaker 1: hole's magnetic field come from? Because I guess black holes 480 00:22:46,800 --> 00:22:49,160 Speaker 1: have a magnetic field. Do we know that for sure. 481 00:22:49,240 --> 00:22:53,080 Speaker 2: Well, we do measure very strong magnetic fields near black holes. 482 00:22:53,240 --> 00:22:54,200 Speaker 1: How do we measure them? 483 00:22:54,280 --> 00:22:56,159 Speaker 2: How do we measure them? Great question? Well, we can 484 00:22:56,240 --> 00:22:59,520 Speaker 2: see the effect, right. Sometimes black holes have enormous jets 485 00:22:59,600 --> 00:23:02,240 Speaker 2: of stuff that shoot up and down on their north 486 00:23:02,280 --> 00:23:05,119 Speaker 2: and south poles, and we think that comes from the 487 00:23:05,160 --> 00:23:08,760 Speaker 2: magnetic field, like funneling particles up and down, sort of 488 00:23:08,760 --> 00:23:11,720 Speaker 2: the same way that the Earth's magnetic field causes northern lights. 489 00:23:12,119 --> 00:23:15,080 Speaker 2: Charged particles coming towards the earth magnetic field get funneled 490 00:23:15,160 --> 00:23:17,680 Speaker 2: up towards the north and south poles. Particles falling into 491 00:23:17,680 --> 00:23:20,400 Speaker 2: a black hole sometimes will miss because the magnetic field 492 00:23:20,440 --> 00:23:23,480 Speaker 2: will deflect them up and down, and you get these enormous, 493 00:23:23,600 --> 00:23:27,000 Speaker 2: like thousands of light years long jets of stuff shooting 494 00:23:27,040 --> 00:23:29,840 Speaker 2: out of black holes. We think from the magnetic fields. 495 00:23:29,920 --> 00:23:31,920 Speaker 1: Well, I guess, first of all, we think those are 496 00:23:32,160 --> 00:23:35,200 Speaker 1: black holes and that those jets are coming from black holes. 497 00:23:35,280 --> 00:23:37,760 Speaker 1: Don't Like, we haven't actually seen the inside of what's 498 00:23:37,800 --> 00:23:38,719 Speaker 1: inside of those jets. 499 00:23:38,800 --> 00:23:40,920 Speaker 2: We've study those jets in some great detail, and we 500 00:23:41,000 --> 00:23:44,240 Speaker 2: have really pretty good models that predict those jets. Recently, 501 00:23:44,280 --> 00:23:47,000 Speaker 2: we imaged a couple of black holes and saw ripples 502 00:23:47,040 --> 00:23:49,320 Speaker 2: in the accretion disk around them, and so we're able 503 00:23:49,400 --> 00:23:52,280 Speaker 2: to like really pin down the details of the magnetic 504 00:23:52,320 --> 00:23:54,919 Speaker 2: field near the black hole. I mean, we'd love to 505 00:23:54,920 --> 00:23:57,320 Speaker 2: send a probe near the black hole and measure those directly, 506 00:23:57,840 --> 00:23:59,760 Speaker 2: but there's a lot of indirect ways to measure those 507 00:23:59,800 --> 00:24:02,520 Speaker 2: magnetic fields, just by seeing the impact to have on 508 00:24:02,680 --> 00:24:04,520 Speaker 2: charge particles near the black hole. 509 00:24:05,040 --> 00:24:06,280 Speaker 1: And I guess the other question is, how do he 510 00:24:06,359 --> 00:24:08,640 Speaker 1: knows those magnetic fields are coming from the black hole 511 00:24:08,760 --> 00:24:10,359 Speaker 1: enough from the stuff around the black hole. 512 00:24:10,440 --> 00:24:12,119 Speaker 2: Yeah, that's a great question, and we don't know the 513 00:24:12,119 --> 00:24:15,159 Speaker 2: answer to that. We're sure that the stuff around the 514 00:24:15,160 --> 00:24:18,440 Speaker 2: black hole can make a magnetic field. Those are charged particles. 515 00:24:18,480 --> 00:24:20,280 Speaker 2: They're moving in a circle, so you have a current 516 00:24:20,359 --> 00:24:22,800 Speaker 2: moving in a circle that always generates a magnetic field. 517 00:24:22,880 --> 00:24:25,440 Speaker 2: The second part is thinking about whether a black hole 518 00:24:25,520 --> 00:24:29,000 Speaker 2: on its own could have a magnetic field even without 519 00:24:29,160 --> 00:24:32,120 Speaker 2: the accretion disc, even without the stuff swirling around it. 520 00:24:32,480 --> 00:24:35,360 Speaker 2: Whether just the black hole itself can have a magnetic 521 00:24:35,359 --> 00:24:36,879 Speaker 2: field is a really interesting question. 522 00:24:37,600 --> 00:24:40,159 Speaker 1: Do we know the answer? Does a black hole on 523 00:24:40,240 --> 00:24:42,520 Speaker 1: its own have an inherent magnetic field? 524 00:24:42,560 --> 00:24:45,320 Speaker 2: So we can answer that question theoretically, We've never seen 525 00:24:45,359 --> 00:24:48,600 Speaker 2: a black hole all by itself, without an accretion disk 526 00:24:48,720 --> 00:24:51,840 Speaker 2: and measured it. But according to general relativity, black holes 527 00:24:51,960 --> 00:24:55,520 Speaker 2: can have magnetic fields. And that's because black holes can 528 00:24:55,560 --> 00:24:58,280 Speaker 2: do two crucial things. One they can have an electric 529 00:24:58,400 --> 00:25:02,200 Speaker 2: charge and two they can can spin. And essentially anything 530 00:25:02,240 --> 00:25:05,240 Speaker 2: with an electric charge that spins has a magnetic field. 531 00:25:05,400 --> 00:25:07,440 Speaker 1: But you're saying it's all theoretical though. 532 00:25:07,520 --> 00:25:10,520 Speaker 2: It's theoretical because we've never observed a black hole without 533 00:25:10,560 --> 00:25:13,480 Speaker 2: any stuff around it and measured its magnetic field. That 534 00:25:13,480 --> 00:25:14,720 Speaker 2: would be an awesome test. 535 00:25:14,520 --> 00:25:16,959 Speaker 1: Of this theory, I see. So basically we don't know. 536 00:25:21,280 --> 00:25:23,880 Speaker 2: Yeah, that's true of lots of things. I suppose. We're 537 00:25:23,920 --> 00:25:25,560 Speaker 2: not sure about it, but we do have a pretty 538 00:25:25,560 --> 00:25:28,200 Speaker 2: good idea. And lots of our models of spinning black 539 00:25:28,200 --> 00:25:31,440 Speaker 2: holes and black holes with charge have been tested indirectly. 540 00:25:31,720 --> 00:25:33,920 Speaker 2: We've never done this exact test. 541 00:25:34,080 --> 00:25:39,120 Speaker 1: Okay, So you're saying theoretically black holes do have magnetic 542 00:25:39,160 --> 00:25:42,159 Speaker 1: fields because they somehow preserve it, right even though you 543 00:25:42,320 --> 00:25:45,240 Speaker 1: when you throw charge particles in it with spin in 544 00:25:45,320 --> 00:25:49,000 Speaker 1: it and magnetic fields, presumably that doesn't get destroyed by. 545 00:25:48,880 --> 00:25:51,359 Speaker 2: The black hole exactly. And Ryan is asking about, like 546 00:25:51,440 --> 00:25:53,960 Speaker 2: where that magnetic field might come from. Because you can't 547 00:25:53,960 --> 00:25:56,720 Speaker 2: see anything beyond the event horizon, So you can't have 548 00:25:56,840 --> 00:26:01,360 Speaker 2: like swirling matter within the event horizon and causing this 549 00:26:01,440 --> 00:26:04,720 Speaker 2: magnetic field. Why not, Because the details of anything like 550 00:26:04,760 --> 00:26:07,639 Speaker 2: that happening within the event horizon is shielded by the 551 00:26:07,680 --> 00:26:10,400 Speaker 2: event horizon. You can only know a few things about 552 00:26:10,400 --> 00:26:13,119 Speaker 2: what's happening inside the event horizon. You can know the 553 00:26:13,119 --> 00:26:16,439 Speaker 2: total mass, you can know the electric charge, and you 554 00:26:16,480 --> 00:26:17,359 Speaker 2: can know the spin. 555 00:26:17,840 --> 00:26:19,800 Speaker 1: Meaning even if there are a bunch of electron spinning 556 00:26:19,840 --> 00:26:22,240 Speaker 1: inside of a black hole, the magnetic field they would 557 00:26:22,240 --> 00:26:25,520 Speaker 1: generate couldn't leak out of the black hole. Is that 558 00:26:25,560 --> 00:26:28,800 Speaker 1: what you're saying, Because the space would just be pointing inwards. 559 00:26:29,080 --> 00:26:31,360 Speaker 2: A lot of the details of what's happening to those 560 00:26:31,400 --> 00:26:34,480 Speaker 2: electrons you wouldn't be sensitive to, Like if one electron 561 00:26:34,840 --> 00:26:37,520 Speaker 2: zigs up or zigs down, you couldn't sense that from 562 00:26:37,520 --> 00:26:40,280 Speaker 2: the outside. You can, however, sense that there are a 563 00:26:40,320 --> 00:26:43,840 Speaker 2: bunch of electrons, and you can sense that they're spinning overall, 564 00:26:43,920 --> 00:26:46,440 Speaker 2: because you can measure the total spin of the black 565 00:26:46,480 --> 00:26:49,560 Speaker 2: hole and the total electric charge of the black hole. 566 00:26:49,720 --> 00:26:53,080 Speaker 2: Like when electron falls into a black hole, just before 567 00:26:53,080 --> 00:26:55,360 Speaker 2: it falls in, it has an electric field, and when 568 00:26:55,359 --> 00:26:57,720 Speaker 2: it falls in, that electric field is now frozen on 569 00:26:57,760 --> 00:27:00,040 Speaker 2: the outside of the black hole. Whatever happened to the 570 00:27:00,040 --> 00:27:02,960 Speaker 2: electron after it falls in can no longer change that 571 00:27:03,040 --> 00:27:05,840 Speaker 2: electric field. It's sort of frozen there. So you can 572 00:27:05,880 --> 00:27:08,680 Speaker 2: tell that something has fallen in and that it had charge, 573 00:27:08,720 --> 00:27:12,240 Speaker 2: but the details what happens afterwards you're shielded from. 574 00:27:12,280 --> 00:27:14,880 Speaker 1: So then are you saying, like, to get the magnetic 575 00:27:14,920 --> 00:27:17,640 Speaker 1: field of a black hole, you just multiply its charged 576 00:27:17,680 --> 00:27:20,360 Speaker 1: by its spin somehow, and that gives you like what 577 00:27:20,440 --> 00:27:22,960 Speaker 1: you would feel as a magnetic field outside of the 578 00:27:22,960 --> 00:27:26,919 Speaker 1: black hole. But those are like overall numbers, not related 579 00:27:26,960 --> 00:27:28,640 Speaker 1: to anything in detail inside of it. 580 00:27:28,760 --> 00:27:31,639 Speaker 2: Exactly in the same way that an electron has a 581 00:27:31,680 --> 00:27:34,280 Speaker 2: little magnetic field. Right where does the magnetic field an 582 00:27:34,280 --> 00:27:37,199 Speaker 2: electron come from. It doesn't have a magnetic charge, It 583 00:27:37,240 --> 00:27:40,720 Speaker 2: has an electric charge, and it has quantum spin. Those 584 00:27:40,760 --> 00:27:43,760 Speaker 2: two things combined to give the electron a tiny little 585 00:27:43,840 --> 00:27:47,600 Speaker 2: magnetic direction, a magnetic dipole. And you can't tell what's 586 00:27:47,600 --> 00:27:49,600 Speaker 2: going on inside the electron. We think maybe it's a 587 00:27:49,600 --> 00:27:52,160 Speaker 2: fundamental particle. We have no idea. We can't see inside, 588 00:27:52,240 --> 00:27:54,639 Speaker 2: and it doesn't matter. We know it has an overall 589 00:27:54,760 --> 00:27:57,480 Speaker 2: charge and an overall spin, and so the overall charge 590 00:27:57,480 --> 00:28:00,520 Speaker 2: and spin of a black hole similarly gives it a 591 00:28:00,560 --> 00:28:02,840 Speaker 2: magnetic moment. It's a magnetic dipole. 592 00:28:03,040 --> 00:28:06,080 Speaker 1: I wonder if, like Ryan's question was more like, you know, 593 00:28:06,119 --> 00:28:08,520 Speaker 1: how can a black hole have a magnetic field if 594 00:28:08,520 --> 00:28:11,000 Speaker 1: nothing can escape it? You know what I mean? Like, 595 00:28:11,440 --> 00:28:14,240 Speaker 1: if the electromagnetic field it has is due to the 596 00:28:14,640 --> 00:28:17,560 Speaker 1: stuff inside of the black hole, how can its magnetism 597 00:28:17,680 --> 00:28:18,600 Speaker 1: escape the black hole? 598 00:28:18,760 --> 00:28:20,880 Speaker 2: Yeah, that's a great question. We have a whole episode 599 00:28:20,920 --> 00:28:24,280 Speaker 2: on how black holes can have magnetic fields and electric 600 00:28:24,320 --> 00:28:28,280 Speaker 2: fields and digs into the details of this question. Very briefly, though, 601 00:28:28,520 --> 00:28:32,679 Speaker 2: The answer is that the overall charge is essentially spread 602 00:28:32,720 --> 00:28:35,720 Speaker 2: out on the event horizon. So something falls into a 603 00:28:35,720 --> 00:28:38,880 Speaker 2: black hole, you're not getting information from within the event horizon. 604 00:28:38,920 --> 00:28:42,240 Speaker 2: You're just getting information from the event horizon. So think 605 00:28:42,240 --> 00:28:45,320 Speaker 2: about the event horizon itself as now having that charge 606 00:28:45,360 --> 00:28:48,040 Speaker 2: and having that spin. There might be crazy stuff going 607 00:28:48,080 --> 00:28:52,240 Speaker 2: on inside, weird quantum effects or singularities orringularities or whatever. 608 00:28:52,680 --> 00:28:55,360 Speaker 2: You can't tell, but you can tell that something charged 609 00:28:55,400 --> 00:28:57,960 Speaker 2: fell in, and you can tell without getting any information 610 00:28:58,000 --> 00:29:00,600 Speaker 2: about what's going on. Inside the event horizon. 611 00:29:01,240 --> 00:29:03,320 Speaker 1: It sort of sounds like you're saying that the black 612 00:29:03,320 --> 00:29:06,640 Speaker 1: hole's magnetic field comes from its surface, Like it's the 613 00:29:06,680 --> 00:29:09,720 Speaker 1: surface of the black hole. That's basically you know, phasing 614 00:29:09,720 --> 00:29:11,719 Speaker 1: out to the rest of the universe, and you know, 615 00:29:12,240 --> 00:29:15,120 Speaker 1: emanating an electric charge and an electric field, and that's 616 00:29:15,120 --> 00:29:15,960 Speaker 1: why we can see it. 617 00:29:16,120 --> 00:29:17,920 Speaker 2: Yeah, that's a good way to think about it. The 618 00:29:17,920 --> 00:29:20,840 Speaker 2: event horizon, or the surface of it equivalently, has three 619 00:29:20,880 --> 00:29:24,920 Speaker 2: properties mass, spin, and charge, and we can measure those 620 00:29:24,960 --> 00:29:26,720 Speaker 2: and those have an effect on the rest of the 621 00:29:26,800 --> 00:29:28,880 Speaker 2: universe right the same way, like the mass of the 622 00:29:28,880 --> 00:29:31,440 Speaker 2: black hole, even though it's contained within the event horizon, 623 00:29:31,640 --> 00:29:34,680 Speaker 2: still curves space outside the event horizon and can affect 624 00:29:34,720 --> 00:29:37,080 Speaker 2: the trajectories of stuff. Think of that as a property 625 00:29:37,200 --> 00:29:40,239 Speaker 2: of the event horizon. It doesn't matter what's going on 626 00:29:40,360 --> 00:29:42,720 Speaker 2: inside behind the screen of the event horizon, if things 627 00:29:42,720 --> 00:29:45,120 Speaker 2: are swirling around or not. All you know is the 628 00:29:45,160 --> 00:29:48,479 Speaker 2: overall mass, the overall charge, and the overall spin, and 629 00:29:48,520 --> 00:29:50,040 Speaker 2: that can create a magnetic field. 630 00:29:50,600 --> 00:29:53,400 Speaker 1: But again, time slows down almost to a standstill near 631 00:29:53,440 --> 00:29:56,720 Speaker 1: the event horizon. How does the magnetic field ever get out? 632 00:29:57,440 --> 00:30:00,320 Speaker 1: Don't have to wait to infinity to feel that magnetic. 633 00:30:00,440 --> 00:30:03,040 Speaker 2: Yes, so time near the black hole is really really 634 00:30:03,120 --> 00:30:06,840 Speaker 2: slowed down, not slowed down totally to infinity. So black 635 00:30:06,840 --> 00:30:10,240 Speaker 2: holes can radiate information for example, like if a black 636 00:30:10,240 --> 00:30:13,360 Speaker 2: hole gets accelerated by another black hole, it can radiate 637 00:30:13,400 --> 00:30:16,360 Speaker 2: a gravitational wave, or if it has charge, it will 638 00:30:16,360 --> 00:30:19,800 Speaker 2: also radiate photons. Again, these are coming from the surface 639 00:30:19,840 --> 00:30:21,960 Speaker 2: of the black hole, not from within it, so we're 640 00:30:22,000 --> 00:30:24,600 Speaker 2: not breaking the rules of black holes, but they can 641 00:30:24,800 --> 00:30:27,520 Speaker 2: radiate that information. And you're right that things near black 642 00:30:27,520 --> 00:30:30,160 Speaker 2: holes are slowed down, and so it does take longer. 643 00:30:30,360 --> 00:30:33,760 Speaker 2: And like those gravitational waves are slowed down by the 644 00:30:33,840 --> 00:30:37,480 Speaker 2: time dilation of the gravitational field. So without that effect, 645 00:30:37,640 --> 00:30:40,720 Speaker 2: those gravitational waves would look much crazier and the photons 646 00:30:40,760 --> 00:30:44,000 Speaker 2: would be much higher frequency. But they're stretched out and 647 00:30:44,080 --> 00:30:46,760 Speaker 2: red shifted by that time dilation, not all the way 648 00:30:46,800 --> 00:30:50,480 Speaker 2: to infinity, because the curvature isn't infinity outside the black hole. 649 00:30:50,520 --> 00:30:52,360 Speaker 1: All right, Well, it sounds like the answer for Ryan 650 00:30:52,520 --> 00:30:55,160 Speaker 1: is that a black hole's magnetic field comes from its surface. 651 00:30:55,200 --> 00:30:58,120 Speaker 1: It's event horizon basically, or at least we can practically 652 00:30:58,120 --> 00:31:00,680 Speaker 1: think of it as coming from the surface and the 653 00:31:00,720 --> 00:31:03,400 Speaker 1: event horizon and that's why we're able to see it 654 00:31:03,480 --> 00:31:07,640 Speaker 1: and experience it. We think, we think we don't know 655 00:31:07,760 --> 00:31:09,960 Speaker 1: for sure because it's a black hole. 656 00:31:10,080 --> 00:31:12,000 Speaker 2: We don't know for sure anything. We don't even know 657 00:31:12,040 --> 00:31:14,760 Speaker 2: if we exist or if this is a simulation. And 658 00:31:14,880 --> 00:31:17,360 Speaker 2: also remember that most of the encnic fields we've measured 659 00:31:17,560 --> 00:31:21,080 Speaker 2: probably do mostly come from the accretion disk of stuff 660 00:31:21,120 --> 00:31:23,480 Speaker 2: around them. But that's where he says we don't know 661 00:31:23,520 --> 00:31:23,880 Speaker 2: for sure. 662 00:31:24,120 --> 00:31:26,440 Speaker 1: All right, Well, let's get to our last question of 663 00:31:26,520 --> 00:31:30,960 Speaker 1: the day, which is about the expanding universe and gravity 664 00:31:31,080 --> 00:31:33,840 Speaker 1: and the Big Bang. But first let's take another quick break. 665 00:31:46,440 --> 00:31:49,960 Speaker 1: All right, we're answering listener questions here, our favorite kind 666 00:31:49,960 --> 00:31:52,760 Speaker 1: of episode where we take your questions that you send 667 00:31:52,800 --> 00:31:55,920 Speaker 1: in and we try to answer them, usually with answers 668 00:31:55,920 --> 00:31:57,080 Speaker 1: that are not we don't know. 669 00:31:58,840 --> 00:31:59,640 Speaker 2: We do our best. 670 00:32:00,120 --> 00:32:03,719 Speaker 1: Sometimes nobody knows which is an answer technically it is. 671 00:32:03,800 --> 00:32:06,800 Speaker 2: And I wonder if that's like really satisfying because it 672 00:32:06,880 --> 00:32:09,040 Speaker 2: means for the listener like, Ooh, I'm at the forefront 673 00:32:09,040 --> 00:32:12,240 Speaker 2: of human knowledge or really disappointing because like the rest 674 00:32:12,240 --> 00:32:14,560 Speaker 2: of humanity is still left unsatisfied. 675 00:32:15,200 --> 00:32:17,200 Speaker 1: Yeah, I guess it is pretty exciting, right to be 676 00:32:17,600 --> 00:32:22,400 Speaker 1: to like come up against the boundary of human knowledge, right, yeah, exactly, 677 00:32:22,520 --> 00:32:23,880 Speaker 1: Like when I ask you a question and you don't 678 00:32:23,920 --> 00:32:25,360 Speaker 1: know the answer, I'm like, Wow, I am at the 679 00:32:25,400 --> 00:32:27,600 Speaker 1: boundary of Daniel's knowledge of the universe. 680 00:32:28,720 --> 00:32:31,320 Speaker 2: Now, the boundary of Daniel's knowledge not the same as 681 00:32:31,320 --> 00:32:34,080 Speaker 2: the boundary knowledge. Let's not make that. 682 00:32:34,080 --> 00:32:38,080 Speaker 1: Mistake, or at least the boundary of the research you've 683 00:32:38,080 --> 00:32:40,720 Speaker 1: been able to do for the last hour before the podcast. 684 00:32:41,240 --> 00:32:43,720 Speaker 2: Exactly, I am at the boundary of human knowledge in 685 00:32:43,760 --> 00:32:47,440 Speaker 2: one time is a little corner of the vast sphere 686 00:32:47,600 --> 00:32:48,720 Speaker 2: of human knowledge. 687 00:32:49,240 --> 00:32:51,200 Speaker 1: Well, we're all here with you, and so our last 688 00:32:51,280 --> 00:32:54,200 Speaker 1: question of the day comes from Argent phor Daniel. 689 00:32:54,440 --> 00:32:57,400 Speaker 5: I have a question. Just got me thinking while I 690 00:32:57,440 --> 00:33:00,720 Speaker 5: was on the shore. We've come to understand that gravity 691 00:33:01,080 --> 00:33:06,240 Speaker 5: is bending of space time, and that's objects which would 692 00:33:06,240 --> 00:33:09,320 Speaker 5: normally travel in a straight line tend to take a 693 00:33:09,360 --> 00:33:12,880 Speaker 5: curve path around the body, which is distorting space time. 694 00:33:13,920 --> 00:33:16,400 Speaker 5: We also know that space itself is expanding in the 695 00:33:16,520 --> 00:33:20,800 Speaker 5: universe for the last ever since Big Bang happened. Do 696 00:33:20,920 --> 00:33:24,440 Speaker 5: we think the effects of gravity have changed over the 697 00:33:24,520 --> 00:33:28,600 Speaker 5: last couple billion years or do we expect it to 698 00:33:28,640 --> 00:33:31,040 Speaker 5: be different later now that we know that space itself 699 00:33:31,120 --> 00:33:34,880 Speaker 5: is expanding or stretching or thinning out, whatever you may 700 00:33:34,880 --> 00:33:38,560 Speaker 5: call it. Will that effect the way gravity acts and 701 00:33:38,600 --> 00:33:41,000 Speaker 5: behaves or has it changed over the years? 702 00:33:41,000 --> 00:33:41,720 Speaker 2: What do you reckon? 703 00:33:42,200 --> 00:33:45,200 Speaker 1: Awesome question? What do we reckon? Daniel? Do we know 704 00:33:45,240 --> 00:33:46,200 Speaker 1: the answer? In this case? 705 00:33:47,200 --> 00:33:49,840 Speaker 2: I reckon that Urgent probably takes really long showers to 706 00:33:49,880 --> 00:33:52,160 Speaker 2: have such deep thoughts about the whole. 707 00:33:51,960 --> 00:33:55,640 Speaker 1: History of the universe, which is awesome. Thank you Argent 708 00:33:55,720 --> 00:33:56,760 Speaker 1: for such a great question. 709 00:33:56,920 --> 00:33:59,880 Speaker 2: So, as usual, we have some ideas about how this works, 710 00:34:00,120 --> 00:34:03,360 Speaker 2: but there's lots that we still don't understand, especially about 711 00:34:03,400 --> 00:34:06,840 Speaker 2: the expanding and the accelerating expansion of the universe. 712 00:34:07,000 --> 00:34:09,399 Speaker 1: Okay, let me see if I understand Argent's question. He's 713 00:34:09,440 --> 00:34:12,600 Speaker 1: in the shower and he's wondering, you know, the universe 714 00:34:12,760 --> 00:34:15,400 Speaker 1: since the Big Bang has, first of all, it expanded 715 00:34:15,440 --> 00:34:18,440 Speaker 1: really fast. Space itself expanded really fast, and space today 716 00:34:18,480 --> 00:34:21,600 Speaker 1: is still expanding, and there's more and more space growing 717 00:34:21,640 --> 00:34:24,279 Speaker 1: and being created. The universe is expanding due to something 718 00:34:24,280 --> 00:34:27,680 Speaker 1: called dark energy. And I think his question is like, 719 00:34:27,960 --> 00:34:31,360 Speaker 1: is gravity affected by this expansion of space? Like do 720 00:34:31,440 --> 00:34:35,120 Speaker 1: we know if gravity itself has been the same and 721 00:34:35,200 --> 00:34:37,520 Speaker 1: for the last fourteen billion years or is there an 722 00:34:37,520 --> 00:34:40,520 Speaker 1: indication that maybe as a universe expands it could be 723 00:34:40,640 --> 00:34:43,920 Speaker 1: changing the effects of gravity like this gravity space dependent. 724 00:34:44,120 --> 00:34:46,520 Speaker 1: What do you reckon, Daniel, I. 725 00:34:46,440 --> 00:34:48,279 Speaker 2: Think there's a crucial piece of the history of the 726 00:34:48,400 --> 00:34:51,440 Speaker 2: universe that you sort of yaddiyauted over there, because you're right, 727 00:34:51,480 --> 00:34:53,960 Speaker 2: the things did expand very quickly in the beginning, but 728 00:34:54,000 --> 00:34:57,680 Speaker 2: then then expansion actually decelerated because the stuff in the 729 00:34:57,760 --> 00:35:01,359 Speaker 2: universe slowed down the expansion. And then later on, like 730 00:35:01,480 --> 00:35:04,400 Speaker 2: six billion years ago, it started picking up again and 731 00:35:04,400 --> 00:35:06,920 Speaker 2: it started to accelerate the expansion. So this is funny, 732 00:35:07,000 --> 00:35:09,240 Speaker 2: sort of like zigzag in the history of the universe. 733 00:35:09,320 --> 00:35:13,080 Speaker 2: It wasn't always just accelerating expansion. It was always expansion, 734 00:35:13,320 --> 00:35:15,680 Speaker 2: but there was a period when that expansion was decelerating. 735 00:35:15,840 --> 00:35:18,280 Speaker 2: I emphasized that not just because it's a cool zigzag, 736 00:35:18,480 --> 00:35:20,760 Speaker 2: but to underline something which I think is in crucial 737 00:35:20,800 --> 00:35:24,400 Speaker 2: to answering Argin's question, which is that's part of gravity. 738 00:35:24,600 --> 00:35:28,440 Speaker 2: Gravity is not just things pulling themselves together, it's also 739 00:35:28,719 --> 00:35:31,920 Speaker 2: space expanding. That is general relativity, our framework that we 740 00:35:32,000 --> 00:35:34,719 Speaker 2: have and what Argent describes as like things moving through 741 00:35:34,760 --> 00:35:38,120 Speaker 2: bent space time that allows for the universe to expand. 742 00:35:38,160 --> 00:35:40,279 Speaker 2: That's sort of part of what gravity is. 743 00:35:40,719 --> 00:35:44,360 Speaker 1: Well, what do you mean, like it's in the equations 744 00:35:44,400 --> 00:35:46,840 Speaker 1: of our theories of gravity for the universe to expand 745 00:35:46,920 --> 00:35:47,880 Speaker 1: due to dark energy. 746 00:35:48,040 --> 00:35:50,920 Speaker 2: It's part of general relativity that the universe can expand 747 00:35:51,120 --> 00:35:54,759 Speaker 2: under certain conditions. So the broad answer to Argent's question is, 748 00:35:54,800 --> 00:35:57,040 Speaker 2: we think the rules of the universe, the rules of 749 00:35:57,040 --> 00:36:00,000 Speaker 2: gravity and space time and general relativity have not changed 750 00:36:00,040 --> 00:36:02,600 Speaker 2: changed over the last fourteen billion years, and we can 751 00:36:02,600 --> 00:36:05,799 Speaker 2: describe all of these weird epics of the universe using 752 00:36:05,880 --> 00:36:08,799 Speaker 2: one consistent framework, and that's sort of amazing. So the 753 00:36:08,880 --> 00:36:11,799 Speaker 2: rules haven't changed, even though the conditions do change from 754 00:36:11,840 --> 00:36:14,080 Speaker 2: year to year and things get further apart and whatever. 755 00:36:14,200 --> 00:36:17,960 Speaker 2: So there are specific conditions under which general relativity predicts 756 00:36:18,000 --> 00:36:21,440 Speaker 2: the universe will expand and that that expansion will accelerate. 757 00:36:22,000 --> 00:36:24,680 Speaker 2: If you have a bunch of energy inherent in space 758 00:36:24,800 --> 00:36:27,759 Speaker 2: stored in a field that has high potential energy, then 759 00:36:27,800 --> 00:36:31,919 Speaker 2: general relativity says space will expand and that expansion will accelerate. 760 00:36:32,000 --> 00:36:34,120 Speaker 2: So we see that happening in the universe. We look 761 00:36:34,160 --> 00:36:36,000 Speaker 2: back at the history of the universe, we see it's 762 00:36:36,040 --> 00:36:39,200 Speaker 2: expanding we see that expansion is accelerating, and so we say, oh, 763 00:36:39,400 --> 00:36:42,400 Speaker 2: there must be some energy stored in a field somewhere 764 00:36:42,400 --> 00:36:45,040 Speaker 2: with a lot of potential energy that's causing this. We 765 00:36:45,080 --> 00:36:46,719 Speaker 2: don't know what that is. We don't know what that 766 00:36:46,760 --> 00:36:49,320 Speaker 2: field is, We have no explanation for it. But general 767 00:36:49,320 --> 00:36:51,319 Speaker 2: relativity can accommodate that well. 768 00:36:51,600 --> 00:36:54,000 Speaker 1: I think what you're saying is that physicists have a 769 00:36:54,040 --> 00:36:57,359 Speaker 1: set of equations that explain the universe, and that set 770 00:36:57,360 --> 00:37:00,200 Speaker 1: of equations has gravity in it, and it also as 771 00:37:00,280 --> 00:37:02,160 Speaker 1: expansion of the universe in it. So it's like they're 772 00:37:02,200 --> 00:37:05,800 Speaker 1: all actually kind of connected already into theories of physics. 773 00:37:05,960 --> 00:37:06,640 Speaker 2: Yes, exactly. 774 00:37:06,640 --> 00:37:08,120 Speaker 1: So it's not like one of them we don't know 775 00:37:08,160 --> 00:37:09,480 Speaker 1: if one of them is doing something the other one 776 00:37:09,520 --> 00:37:09,920 Speaker 1: doesn't know. 777 00:37:10,040 --> 00:37:12,839 Speaker 2: That's right. And when people say gravity colloquially, they mean 778 00:37:12,920 --> 00:37:16,600 Speaker 2: like stuff attracting and things falling towards planets and whatever. 779 00:37:16,920 --> 00:37:19,440 Speaker 2: When physicists say gravity, they mean the whole shebang, They 780 00:37:19,480 --> 00:37:21,520 Speaker 2: mean the whole theory of space, time and all of 781 00:37:21,520 --> 00:37:25,120 Speaker 2: its consequences. Because moving from like a Newtonian view of 782 00:37:25,120 --> 00:37:28,279 Speaker 2: gravity as a force to an Einsteinian view of gravity 783 00:37:28,360 --> 00:37:31,840 Speaker 2: as motion of stuff through space time has all of 784 00:37:31,880 --> 00:37:35,960 Speaker 2: these consequences, not just oh, light is also bent by gravity, 785 00:37:36,080 --> 00:37:39,000 Speaker 2: but also the universe can expand and it could also collapse. 786 00:37:39,080 --> 00:37:42,000 Speaker 2: All of these things are consequences of this geometric view 787 00:37:42,040 --> 00:37:45,319 Speaker 2: of the universe we have from general relativity, and we 788 00:37:45,400 --> 00:37:47,440 Speaker 2: think that those rules have not changed. That the same 789 00:37:47,520 --> 00:37:49,560 Speaker 2: rules applied in the very very beginning and in the 790 00:37:49,560 --> 00:37:52,600 Speaker 2: middle point when things were decelerating, and now when things 791 00:37:52,640 --> 00:37:55,400 Speaker 2: are accelerating. So in the broadest sense, the rules of 792 00:37:55,480 --> 00:37:58,840 Speaker 2: gravity general relativity have not changed over the course of 793 00:37:58,840 --> 00:37:59,440 Speaker 2: the universe. 794 00:38:00,239 --> 00:38:02,560 Speaker 1: I see, like the rules by which you mean the equations, 795 00:38:02,560 --> 00:38:04,600 Speaker 1: But I wonder if Argin means, like, you know, imagine 796 00:38:04,640 --> 00:38:07,200 Speaker 1: there's a term in your equations for gravity. I wonder 797 00:38:07,239 --> 00:38:09,640 Speaker 1: if he could mean that, you know, has that term 798 00:38:09,680 --> 00:38:13,080 Speaker 1: the equation change as the universe grew? Like could it 799 00:38:13,120 --> 00:38:15,680 Speaker 1: that be something the equations don't take into account, or 800 00:38:15,680 --> 00:38:17,680 Speaker 1: it could it be something we haven't noticed. 801 00:38:17,360 --> 00:38:19,719 Speaker 2: Or or what. Yeah, there's a couple of ways in 802 00:38:19,760 --> 00:38:21,760 Speaker 2: which that could be true. First of all, we assume 803 00:38:21,880 --> 00:38:25,040 Speaker 2: that dark energy or whatever this is, this potential field 804 00:38:25,040 --> 00:38:28,160 Speaker 2: that's causing the accelerating expansion in the universe. We assume 805 00:38:28,160 --> 00:38:30,800 Speaker 2: that that's constant everywhere in space and everywhere in time, 806 00:38:31,040 --> 00:38:33,160 Speaker 2: and mostly that works. I mean, it said that we 807 00:38:33,200 --> 00:38:35,160 Speaker 2: can explain the whole history of the universe, and that's 808 00:38:35,200 --> 00:38:38,080 Speaker 2: mostly true, but there are some discrepancies, like we measure 809 00:38:38,080 --> 00:38:39,920 Speaker 2: it early in the universe, we measure it late in 810 00:38:39,920 --> 00:38:42,880 Speaker 2: the universe, and those two numbers don't quite agree. You 811 00:38:42,920 --> 00:38:46,000 Speaker 2: can read more about that. It's called the Hubble tension. Essentially, 812 00:38:46,000 --> 00:38:49,040 Speaker 2: that's predicting the rate of expansion, and different measurements don't 813 00:38:49,080 --> 00:38:51,480 Speaker 2: quite agree. So that's quite interesting. So it might be 814 00:38:51,600 --> 00:38:53,879 Speaker 2: that the dark energy is changing over time, and again 815 00:38:53,920 --> 00:38:55,680 Speaker 2: that wouldn't mean a change in the rules, but it 816 00:38:55,719 --> 00:38:58,320 Speaker 2: would mean some change in the conditions, which is affecting 817 00:38:58,440 --> 00:39:01,960 Speaker 2: like your experience of the Union. And also, maybe more importantly, 818 00:39:02,080 --> 00:39:04,600 Speaker 2: the second sense is that the density of stuff in 819 00:39:04,640 --> 00:39:07,160 Speaker 2: the universe is definitely decreasing. Like things used to be 820 00:39:07,200 --> 00:39:09,600 Speaker 2: really hot and dense and now they're very cold and 821 00:39:09,719 --> 00:39:13,240 Speaker 2: very far apart, and so there's definitely like less sense 822 00:39:13,360 --> 00:39:16,640 Speaker 2: of gravity in the universe. Because the mass density of 823 00:39:16,640 --> 00:39:19,319 Speaker 2: stuff in the universe is going down, space goes up, 824 00:39:19,480 --> 00:39:22,480 Speaker 2: the amount of mass doesn't change, so the density decreases, 825 00:39:22,719 --> 00:39:25,800 Speaker 2: things get further and further apart. You're feeling less gravity 826 00:39:26,080 --> 00:39:29,000 Speaker 2: from distant galaxies than you were before because they're now 827 00:39:29,000 --> 00:39:31,239 Speaker 2: further away from you, and that's going to keep going. 828 00:39:31,480 --> 00:39:34,319 Speaker 1: Mm So I guess technically you would be feeling more 829 00:39:34,360 --> 00:39:37,600 Speaker 1: the gravity of Earth right as the universe gets more 830 00:39:37,719 --> 00:39:40,200 Speaker 1: empty and empty, right, Like, I'm way more in the 831 00:39:40,239 --> 00:39:43,600 Speaker 1: future regardless of what I what I do. 832 00:39:45,000 --> 00:39:47,719 Speaker 2: If you're relying on distant gravities to lift you up 833 00:39:47,719 --> 00:39:49,520 Speaker 2: off the surface of the Earth and make you feel light, 834 00:39:49,880 --> 00:39:51,319 Speaker 2: then I have bad news for you. 835 00:39:51,480 --> 00:39:55,840 Speaker 1: Yes, as my diet plan forget as epic. 836 00:40:00,800 --> 00:40:03,600 Speaker 2: Yeah, exactly, I suggest hitting the gym instead of relying 837 00:40:03,600 --> 00:40:06,600 Speaker 2: on distant galaxies. But I'm not a health expert. Don't 838 00:40:06,600 --> 00:40:07,520 Speaker 2: take advice from me. 839 00:40:07,960 --> 00:40:11,000 Speaker 1: Well, I wonder if Argine's question then maybe more simply 840 00:40:11,200 --> 00:40:13,160 Speaker 1: is like, you know, if I have a black hole 841 00:40:13,280 --> 00:40:16,760 Speaker 1: the same mass and I see it bend light around it, 842 00:40:16,800 --> 00:40:19,200 Speaker 1: is it going to bend light the same way now 843 00:40:19,400 --> 00:40:21,920 Speaker 1: in the future, in the past when the universe was 844 00:40:22,000 --> 00:40:25,040 Speaker 1: maybe more scrunched together, or is that light can we 845 00:40:25,120 --> 00:40:27,680 Speaker 1: bend differently depending on what the universe is doing, Like, 846 00:40:27,760 --> 00:40:29,839 Speaker 1: especially like let's say we're going through a period where 847 00:40:30,080 --> 00:40:33,520 Speaker 1: space is expanding faster and faster, or where we're hitting 848 00:40:33,520 --> 00:40:35,000 Speaker 1: you know, in that zig zag, where we're hitting a 849 00:40:35,000 --> 00:40:37,719 Speaker 1: point of maximum expansion, that light is going to bend 850 00:40:37,719 --> 00:40:39,759 Speaker 1: a little bit differently right than it would in a 851 00:40:39,800 --> 00:40:41,640 Speaker 1: period of not so fast expansion. 852 00:40:41,680 --> 00:40:43,600 Speaker 2: All right, So now you've pushed this into a corner 853 00:40:43,640 --> 00:40:46,040 Speaker 2: of general relativity that we don't understand very well. 854 00:40:46,080 --> 00:40:48,680 Speaker 1: So the answer is we don't know, We don't know. 855 00:40:48,960 --> 00:40:52,200 Speaker 2: And also fascinatingly because we don't even understand our own theory, 856 00:40:52,360 --> 00:40:55,240 Speaker 2: like general relativity has no problem with having black holes 857 00:40:55,280 --> 00:40:57,640 Speaker 2: in an expanding universe, but we don't know how to 858 00:40:57,680 --> 00:41:01,799 Speaker 2: do that. Calculation like Einstein's equation are nasty and they're 859 00:41:01,920 --> 00:41:04,520 Speaker 2: very very difficult to solve. We can only solve them 860 00:41:04,520 --> 00:41:07,800 Speaker 2: in very specialized, simplified settings, like you have a black 861 00:41:07,800 --> 00:41:11,040 Speaker 2: hole in an otherwise empty universe that we can solve, 862 00:41:11,440 --> 00:41:14,040 Speaker 2: or you have a universe that's expanding, but the matter 863 00:41:14,120 --> 00:41:16,960 Speaker 2: in it is totally uniform, like dust sprinkled everywhere. We 864 00:41:17,000 --> 00:41:19,360 Speaker 2: don't know how to solve the equations for a black 865 00:41:19,400 --> 00:41:23,120 Speaker 2: hole in an expanding universe or a universe with like 866 00:41:23,239 --> 00:41:26,120 Speaker 2: chunky stuff in it. So we have all these approximations 867 00:41:26,200 --> 00:41:28,759 Speaker 2: and so the specific question you just asked, like what 868 00:41:28,880 --> 00:41:31,279 Speaker 2: happens to a black hole in an expanding universe? We 869 00:41:31,320 --> 00:41:35,600 Speaker 2: don't know how to do that calculation, but we think 870 00:41:35,640 --> 00:41:38,200 Speaker 2: that the rules are not changing, right, and so for 871 00:41:38,320 --> 00:41:40,960 Speaker 2: a black hole, gravity is basically the same as it 872 00:41:41,080 --> 00:41:43,360 Speaker 2: was a billion years ago and five billion years ago, 873 00:41:43,560 --> 00:41:46,520 Speaker 2: Like the nature of space itself is not changing. It 874 00:41:46,520 --> 00:41:49,000 Speaker 2: doesn't thin out, you know, as the universe expands, and 875 00:41:49,040 --> 00:41:51,319 Speaker 2: that expansion accelerats, you just get more space, and that 876 00:41:51,360 --> 00:41:54,600 Speaker 2: space behaves, we think, according to the same rules, and 877 00:41:54,640 --> 00:41:57,040 Speaker 2: so Bend's light the same way as it always did. 878 00:41:57,120 --> 00:41:59,480 Speaker 1: All right, Well, then the answer origin seems to be 879 00:41:59,560 --> 00:42:01,720 Speaker 1: that you don't think that the rules of the universe 880 00:42:01,760 --> 00:42:04,520 Speaker 1: are changing, meaning like what the physicists would consider to 881 00:42:04,520 --> 00:42:06,719 Speaker 1: be gravity, which is the whole set of equations. You 882 00:42:06,719 --> 00:42:09,560 Speaker 1: don't think that's changing. But maybe the effects of a 883 00:42:09,600 --> 00:42:12,000 Speaker 1: black hole might be changing, except you don't know how 884 00:42:12,040 --> 00:42:12,680 Speaker 1: to calculate it. 885 00:42:12,880 --> 00:42:14,520 Speaker 2: That's right. And there was even this fast on any 886 00:42:14,560 --> 00:42:17,480 Speaker 2: paper a few months ago about how like black holes 887 00:42:17,560 --> 00:42:20,120 Speaker 2: might be driving the expansion of the universe, right, that 888 00:42:20,280 --> 00:42:23,480 Speaker 2: black holes might actually be like weird clusters of dark energy. 889 00:42:23,640 --> 00:42:27,120 Speaker 2: So just to highlight like how little we understand the 890 00:42:27,200 --> 00:42:29,960 Speaker 2: expansion of the universe, and how tricky it is to 891 00:42:30,000 --> 00:42:33,000 Speaker 2: do these kind of calculations in any sort of realistic setting. 892 00:42:33,280 --> 00:42:34,360 Speaker 1: Yeah, or in the shower. 893 00:42:36,200 --> 00:42:38,840 Speaker 2: The shower is probably the best place to do these calculations. 894 00:42:39,640 --> 00:42:42,080 Speaker 1: Yeah. Well, if it wasn't for gravity, you couldn't take 895 00:42:42,080 --> 00:42:44,560 Speaker 1: a shower. You definitely any gravity to shower. 896 00:42:44,640 --> 00:42:47,120 Speaker 2: Oh my gosh, wow, thank you gravity. We should be 897 00:42:47,120 --> 00:42:48,880 Speaker 2: saying every time we have a shower. Yeah. 898 00:42:48,960 --> 00:42:51,160 Speaker 1: If not for gravity, we'd all be a little bit stinkier, 899 00:42:51,600 --> 00:42:55,200 Speaker 1: or we'd all have to take baths in zero gravity, 900 00:42:55,200 --> 00:42:57,680 Speaker 1: which I think is dangerous, isn't it, Like you would 901 00:42:57,800 --> 00:43:00,799 Speaker 1: you would very quickly drown because the water would just sing. 902 00:43:00,880 --> 00:43:04,000 Speaker 2: Golf you maybe, But again, don't take health advice from 903 00:43:04,000 --> 00:43:06,960 Speaker 2: this podcast. That is outside our area of expertise. 904 00:43:07,920 --> 00:43:10,799 Speaker 1: Yeah, don't take health advice from a cartoonist, a physicist. 905 00:43:12,840 --> 00:43:15,480 Speaker 2: Stay on your diet whatever it was before this podcast. 906 00:43:15,800 --> 00:43:21,280 Speaker 1: That's right. Listen to a real doctor, not the academic kind, exactly. 907 00:43:21,680 --> 00:43:22,960 Speaker 2: You know what the best thing about. 908 00:43:22,800 --> 00:43:25,040 Speaker 1: Getting your PhD is, there's the best thing. 909 00:43:25,920 --> 00:43:27,840 Speaker 2: Every meeting is now a doctor's appointment. 910 00:43:28,120 --> 00:43:32,839 Speaker 1: There you go. I'm sure everyone loves doctor's appointments. Does 911 00:43:32,840 --> 00:43:35,680 Speaker 1: that mean that this podcast is a doctor's appointment for 912 00:43:35,800 --> 00:43:37,319 Speaker 1: the thousands of people who listen to. 913 00:43:37,280 --> 00:43:42,239 Speaker 2: Us, I guess so. Yeah, oh man, keep your pants on, everyone, Yeah, 914 00:43:42,360 --> 00:43:42,919 Speaker 2: keep your pants. 915 00:43:42,960 --> 00:43:45,600 Speaker 1: How I'm not gonna grab anything or ask you to cough. 916 00:43:46,320 --> 00:43:48,560 Speaker 2: No, the only things we're probing are the nature of 917 00:43:48,600 --> 00:43:52,080 Speaker 2: the universe. The only black holes we're investigating are the 918 00:43:52,080 --> 00:43:54,120 Speaker 2: theoretical kind. That's right. 919 00:43:54,200 --> 00:43:59,279 Speaker 1: That's right, only only physical dark matter that we're interested in. 920 00:43:59,760 --> 00:44:03,800 Speaker 1: All right, Well, that answers Arjie's question and everybody's question again, 921 00:44:03,840 --> 00:44:07,560 Speaker 1: and another interesting journey to the edge of human knowledge 922 00:44:07,600 --> 00:44:10,120 Speaker 1: and the realization of how much we know and still 923 00:44:10,160 --> 00:44:12,919 Speaker 1: have yet to know about the universe, which is kind 924 00:44:12,920 --> 00:44:13,440 Speaker 1: of exciting. 925 00:44:13,800 --> 00:44:16,680 Speaker 2: That's right. So keep asking questions. You'll be surprised how 926 00:44:16,760 --> 00:44:18,120 Speaker 2: quickly you can get. 927 00:44:18,040 --> 00:44:20,400 Speaker 1: To the edge of human knowledge or the edge of 928 00:44:20,400 --> 00:44:21,160 Speaker 1: a black hole. 929 00:44:21,000 --> 00:44:23,879 Speaker 2: Apparently, or the edge of this doctor's appointment, or. 930 00:44:23,800 --> 00:44:27,160 Speaker 1: The edge of this podcast. So we hope you enjoyed that. 931 00:44:27,440 --> 00:44:29,640 Speaker 1: Thanks for joining us, See you next time. 932 00:44:35,080 --> 00:44:38,239 Speaker 2: For more science and curiosity. Come find us on social media, 933 00:44:38,360 --> 00:44:42,920 Speaker 2: where we answer questions and post videos. We're on Twitter, disport, Instant, 934 00:44:43,000 --> 00:44:46,240 Speaker 2: and now TikTok and remember that. Daniel and Jorge Explain 935 00:44:46,280 --> 00:44:50,239 Speaker 2: the Universe is a production of iHeartRadio. For more podcasts 936 00:44:50,320 --> 00:44:54,960 Speaker 2: from iHeartRadio, visit the iHeartRadio Apple Apple Podcasts, or wherever 937 00:44:55,040 --> 00:44:57,080 Speaker 2: you listen to your favorite shows. 938 00:45:00,520 --> 00:45:00,560 Speaker 3: Th