1 00:00:08,480 --> 00:00:12,640 Speaker 1: Hey, Daniel, how's our email inbox looking these days? Is happening? 2 00:00:12,800 --> 00:00:15,400 Speaker 1: There are so many fun questions, and there's so many 3 00:00:15,400 --> 00:00:18,919 Speaker 1: people wondering about the mysteries of the universe. Well, do 4 00:00:18,960 --> 00:00:22,320 Speaker 1: you know if any patterns or trends or maybe frequently 5 00:00:22,360 --> 00:00:25,720 Speaker 1: asked questions? Oh for sure. Actually most of the questions 6 00:00:25,760 --> 00:00:28,920 Speaker 1: we get, our questions we have seen before. Yeah. Really 7 00:00:28,960 --> 00:00:31,080 Speaker 1: a lot of people have the same questions. Yeah, just 8 00:00:31,160 --> 00:00:33,640 Speaker 1: the same concepts tend to trip up a lot of people. 9 00:00:34,320 --> 00:00:38,960 Speaker 1: So if you still don't understand quantum mechanics or relativity, 10 00:00:39,080 --> 00:00:41,800 Speaker 1: you're not the only one. No, In fact, you're in 11 00:00:41,960 --> 00:00:44,760 Speaker 1: very good company because I'm still confused about it. May 12 00:00:44,800 --> 00:00:46,479 Speaker 1: you should submit it as a question to our podcast. 13 00:00:46,600 --> 00:01:06,520 Speaker 1: And who's going to answer it? Not me? I am 14 00:01:06,520 --> 00:01:09,480 Speaker 1: more handmade cartoonists and the creator of PhD Comics. Hi, 15 00:01:09,560 --> 00:01:12,760 Speaker 1: I'm Daniel. I'm a particle physicist and I've never stopped 16 00:01:12,880 --> 00:01:16,200 Speaker 1: asking questions about the universe. And welcome to our podcast, 17 00:01:16,280 --> 00:01:18,959 Speaker 1: Daniel and Jorge Explain the Universe, a production of I 18 00:01:19,080 --> 00:01:22,000 Speaker 1: Heart Radio in which we dive deep into your questions 19 00:01:22,040 --> 00:01:25,160 Speaker 1: about the universe and two scientists questions about the universe 20 00:01:25,160 --> 00:01:28,880 Speaker 1: into everybody's questions about the universe. How does it work? 21 00:01:29,120 --> 00:01:31,080 Speaker 1: What is it made of? Why does it work this 22 00:01:31,120 --> 00:01:33,760 Speaker 1: way and not that way? Why don't I have a 23 00:01:33,760 --> 00:01:37,199 Speaker 1: taco stand around my corner? Every deep and important question 24 00:01:37,280 --> 00:01:40,160 Speaker 1: about the universe handled on one podcast. Have you actually 25 00:01:40,240 --> 00:01:43,880 Speaker 1: checked all four corners? I do a scan every day 26 00:01:43,920 --> 00:01:46,319 Speaker 1: for taco chucks, and there's still not one on my corner. 27 00:01:47,560 --> 00:01:49,920 Speaker 1: You live in southern California and you have trouble finding 28 00:01:49,920 --> 00:01:52,800 Speaker 1: a taco truck. You need to get out more man. Yes, 29 00:01:52,840 --> 00:01:55,760 Speaker 1: that's definitely my problem. Yeah, we all have questions, and 30 00:01:56,120 --> 00:01:58,280 Speaker 1: it seems to be kind of a innate part of 31 00:01:58,440 --> 00:02:01,200 Speaker 1: human nature to be cure us about what's going on 32 00:02:01,280 --> 00:02:04,560 Speaker 1: around them and how things work. And fortunately the universe 33 00:02:05,000 --> 00:02:09,160 Speaker 1: is happy to provide mysteries and strange things for us 34 00:02:09,160 --> 00:02:11,720 Speaker 1: to ask questions about. Yeah, we're lucky that the universe 35 00:02:11,800 --> 00:02:16,120 Speaker 1: is both amazing, beautiful and mysterious. Yet it also seems 36 00:02:16,160 --> 00:02:19,720 Speaker 1: to be discoverable that we have this incredible technique for 37 00:02:19,919 --> 00:02:23,760 Speaker 1: divining knowledge from the universe by asking questions and then 38 00:02:23,800 --> 00:02:26,800 Speaker 1: answering them in a structured way. So we're fortunate to 39 00:02:26,840 --> 00:02:30,520 Speaker 1: be surrounded by amazing but accessible mystery yeah, especially you, 40 00:02:30,560 --> 00:02:33,160 Speaker 1: I guess, because you know the universe was simple and 41 00:02:33,360 --> 00:02:35,720 Speaker 1: easy to understand, we might be out of a job, Daniel, 42 00:02:35,960 --> 00:02:38,680 Speaker 1: that's right, especially if the whole field of physics lasted 43 00:02:38,720 --> 00:02:41,240 Speaker 1: like ten minutes of human history. They're like, let's knock 44 00:02:41,280 --> 00:02:45,280 Speaker 1: that off before lunch. We we've done it, we've done it. 45 00:02:45,440 --> 00:02:47,840 Speaker 1: Fire all the physicists put them to work somewhere else 46 00:02:48,000 --> 00:02:51,359 Speaker 1: doing Mataga trunk. You're right, there is a sort of 47 00:02:51,400 --> 00:02:53,960 Speaker 1: exquisite balance there. Physics was too easy, it'd be done 48 00:02:54,000 --> 00:02:56,120 Speaker 1: too soon. If it was too hard, nobody would give 49 00:02:56,160 --> 00:02:58,200 Speaker 1: us any money because we weren't making any progress. So 50 00:02:58,240 --> 00:03:01,120 Speaker 1: it's got to be just part of to be worth doing. 51 00:03:01,200 --> 00:03:04,040 Speaker 1: And so physicists, as part of their jobs, ask questions 52 00:03:04,040 --> 00:03:06,200 Speaker 1: about the universe, and they all have. They have all 53 00:03:06,280 --> 00:03:09,120 Speaker 1: kinds of amazing questions about how things work. And the 54 00:03:09,160 --> 00:03:11,519 Speaker 1: public also has a lot of questions. And sometimes those 55 00:03:11,600 --> 00:03:13,720 Speaker 1: questions are one and the same. That's right, and we 56 00:03:13,840 --> 00:03:17,000 Speaker 1: on this podcast do our best to answer those questions, 57 00:03:17,000 --> 00:03:18,600 Speaker 1: to dig deep, to explain them to you in a 58 00:03:18,639 --> 00:03:22,919 Speaker 1: way that makes sense. But sometimes our explanations inspire more questions. 59 00:03:23,160 --> 00:03:25,240 Speaker 1: We'll talk about a topic like black holes and then 60 00:03:25,240 --> 00:03:28,200 Speaker 1: we'll get five or ten very similar questions about some 61 00:03:28,280 --> 00:03:31,200 Speaker 1: little wrinkle that we didn't cover or something we said 62 00:03:31,240 --> 00:03:33,560 Speaker 1: that didn't quite make sense to a few people, and 63 00:03:33,600 --> 00:03:35,720 Speaker 1: so we thought it'd be fun to dig into some 64 00:03:35,800 --> 00:03:38,760 Speaker 1: of those emails and answer those questions and iron out 65 00:03:38,800 --> 00:03:41,520 Speaker 1: those wrinkles. So today on the podcast, we'll be tackling 66 00:03:46,280 --> 00:03:50,080 Speaker 1: our most common listener questions. That's right. We have a 67 00:03:50,120 --> 00:03:52,960 Speaker 1: series of episodes on this podcast where we talk about 68 00:03:53,000 --> 00:03:55,920 Speaker 1: the most unusual and interesting listener questions, the ones that 69 00:03:55,920 --> 00:03:58,480 Speaker 1: are sort of tricky and hard and require me to 70 00:03:58,480 --> 00:04:00,840 Speaker 1: do a bunch of research. But there's a whole other 71 00:04:00,920 --> 00:04:03,240 Speaker 1: category of questions that we want to share with you, 72 00:04:03,400 --> 00:04:05,560 Speaker 1: and these are the common questions, the one that a 73 00:04:05,600 --> 00:04:07,880 Speaker 1: lot of people are asking. And so today will be 74 00:04:08,000 --> 00:04:10,480 Speaker 1: asking most of a lot of the top questions that 75 00:04:10,520 --> 00:04:14,600 Speaker 1: we get through email, through Twitter, through Instagram. Daniel, do 76 00:04:14,600 --> 00:04:17,480 Speaker 1: you check Instagram? Do you know what Instagram is? Do 77 00:04:17,520 --> 00:04:20,839 Speaker 1: we have a TikTok account too? I don't use grams 78 00:04:20,880 --> 00:04:22,960 Speaker 1: because you know, I'm an American, and so I use 79 00:04:23,040 --> 00:04:26,800 Speaker 1: instat pounds good. That sounds like a bad diet to 80 00:04:26,920 --> 00:04:30,600 Speaker 1: go on. I don't recommend it. Actually, that's the name 81 00:04:30,640 --> 00:04:33,160 Speaker 1: of my taco truck is instat pounds, so we put 82 00:04:33,200 --> 00:04:36,440 Speaker 1: sour cream on everything. Maybe it's good that you don't 83 00:04:36,440 --> 00:04:39,279 Speaker 1: have a taco truck. Then maybe that's why I don't 84 00:04:39,320 --> 00:04:42,240 Speaker 1: have a talk. Yeah. So we're gonna be asking all 85 00:04:42,240 --> 00:04:44,280 Speaker 1: these questions, and they're all great questions, and they have 86 00:04:44,400 --> 00:04:47,240 Speaker 1: to do with the dark matter and black holes and 87 00:04:47,360 --> 00:04:51,039 Speaker 1: particles and all kinds of things, even philosophical questions and 88 00:04:51,240 --> 00:04:54,000 Speaker 1: questions about life and how to get involved in physics. 89 00:04:54,040 --> 00:04:57,120 Speaker 1: So we'll dive right in. Our first question comes from 90 00:04:57,200 --> 00:05:01,440 Speaker 1: Thomas and he us a question about is there a 91 00:05:01,520 --> 00:05:05,720 Speaker 1: dark matter inside of black holes? And what about neutrinos? Now, 92 00:05:05,720 --> 00:05:07,440 Speaker 1: because he asking if there's a dark matter inside of 93 00:05:07,480 --> 00:05:10,320 Speaker 1: neutrinos or is he asking the neutrinos inside of black hole? 94 00:05:10,360 --> 00:05:12,040 Speaker 1: I think he's asking if he can get a side 95 00:05:12,080 --> 00:05:16,120 Speaker 1: of neutrinos with his tacos. Everyone has a side of 96 00:05:16,200 --> 00:05:18,560 Speaker 1: neutrinos and the tacos, don't they. Yeah. I think that 97 00:05:18,640 --> 00:05:21,600 Speaker 1: this question is basically asking, like what kind of stuff 98 00:05:21,680 --> 00:05:24,919 Speaker 1: gets sucked into a black hole? Dark matter, which we 99 00:05:24,960 --> 00:05:28,040 Speaker 1: know is out there, this invisible kind of matter giving 100 00:05:28,080 --> 00:05:31,280 Speaker 1: gravity to the universe, even though we can't see it, 101 00:05:31,360 --> 00:05:34,279 Speaker 1: does that also get sucked into black holes? And that's 102 00:05:34,440 --> 00:05:37,560 Speaker 1: I think also why he's asking about neutrinos, Like neutrinos 103 00:05:37,920 --> 00:05:40,400 Speaker 1: feel hardly anything and have almost no mask, Did they 104 00:05:40,440 --> 00:05:42,479 Speaker 1: also get sucked into black holes? So I think that's 105 00:05:42,480 --> 00:05:45,080 Speaker 1: the origin of the questions. Are black holes sort of 106 00:05:45,360 --> 00:05:48,880 Speaker 1: universal sucker ruppers or do they only eat regular matter 107 00:05:49,520 --> 00:05:51,479 Speaker 1: like the kind that we're made out of. Yeah, And 108 00:05:51,560 --> 00:05:53,560 Speaker 1: the other angle of this question is, you know, what 109 00:05:53,640 --> 00:05:55,680 Speaker 1: are the structures of dark matter? If dark matter is 110 00:05:55,720 --> 00:05:58,279 Speaker 1: here in the universe, is it just big fluffy clouds, 111 00:05:58,320 --> 00:06:00,839 Speaker 1: or is it making like dark plant? It's dark stars, 112 00:06:00,920 --> 00:06:04,440 Speaker 1: dark black holes, and dark podcasts a right, So is 113 00:06:04,480 --> 00:06:07,480 Speaker 1: there dark matter inside a black holes? Daniel almost certainly. Yes. 114 00:06:08,080 --> 00:06:11,320 Speaker 1: Black holes are basically just very strong sources of gravity, 115 00:06:11,320 --> 00:06:14,120 Speaker 1: and they can suck in anything anything that has mass. 116 00:06:14,480 --> 00:06:17,479 Speaker 1: It doesn't matter if you are moving very fast or 117 00:06:17,520 --> 00:06:20,039 Speaker 1: if you're moving very slow, if you're low mass or 118 00:06:20,120 --> 00:06:23,680 Speaker 1: high mass. All forms of energy are trapped by black holes, 119 00:06:24,120 --> 00:06:27,040 Speaker 1: even if they have no other kinds of interactions. Right. 120 00:06:27,080 --> 00:06:29,279 Speaker 1: That's the thing that makes dark matter unique is that 121 00:06:29,320 --> 00:06:32,000 Speaker 1: we think it has no other kinds of interactions that 122 00:06:32,120 --> 00:06:34,640 Speaker 1: we're aware of. But you can still get sucked into 123 00:06:34,640 --> 00:06:37,440 Speaker 1: a black hole, right, Yeah, I guess the question is 124 00:06:37,640 --> 00:06:40,159 Speaker 1: it can only interact with gravity. I think we have 125 00:06:40,200 --> 00:06:42,799 Speaker 1: a podcast that covers that what would keep it inside 126 00:06:42,800 --> 00:06:45,680 Speaker 1: of the black hole. Couldn't it escape if it wasn't 127 00:06:45,680 --> 00:06:48,040 Speaker 1: being crunched down by other stuff. It's not being crunched 128 00:06:48,040 --> 00:06:51,000 Speaker 1: down by the other stuff, but it's gravity that's holding 129 00:06:51,040 --> 00:06:53,800 Speaker 1: things inside a black hole. Remember, these days, we don't 130 00:06:53,800 --> 00:06:56,120 Speaker 1: think about gravity as a force, so you shouldn't think 131 00:06:56,160 --> 00:06:58,880 Speaker 1: about it like tugging on this stuff and keeping it 132 00:06:58,920 --> 00:07:01,840 Speaker 1: in the black hole. We think of gravity as the 133 00:07:01,880 --> 00:07:05,200 Speaker 1: bending of the shape of space. Einstein told us that 134 00:07:05,320 --> 00:07:08,640 Speaker 1: this is some crazy relationship where matter bends space and 135 00:07:08,640 --> 00:07:11,640 Speaker 1: then space tells matter how to move because of its curvature. 136 00:07:11,920 --> 00:07:15,000 Speaker 1: And a black hole is this crazy intense bending of 137 00:07:15,040 --> 00:07:19,120 Speaker 1: space such that essentially becomes one directional inside a black hole, 138 00:07:19,200 --> 00:07:22,360 Speaker 1: you can only move towards the center. Space is one 139 00:07:22,400 --> 00:07:25,280 Speaker 1: directional inside a black hole, sort of the way time 140 00:07:25,440 --> 00:07:28,160 Speaker 1: is one directional outside a black hole. Time only moves 141 00:07:28,200 --> 00:07:31,280 Speaker 1: forward outside a black hole. Space only moves towards the 142 00:07:31,320 --> 00:07:34,320 Speaker 1: center inside a black hole. So it doesn't really matter 143 00:07:34,600 --> 00:07:36,600 Speaker 1: what you are if you have any mass or energy. 144 00:07:36,800 --> 00:07:38,800 Speaker 1: You are moving towards the center of the black hole 145 00:07:38,880 --> 00:07:40,920 Speaker 1: once you fall in, right, But then once it gets 146 00:07:40,920 --> 00:07:42,960 Speaker 1: to the center, wouldn't it come out the other end 147 00:07:43,080 --> 00:07:44,840 Speaker 1: Once it gets to the center, gravity is going to 148 00:07:45,000 --> 00:07:47,200 Speaker 1: keep holding it at the center, right, I mean, unless 149 00:07:47,240 --> 00:07:49,640 Speaker 1: there's like a wormhole at the center attached to a 150 00:07:49,640 --> 00:07:53,840 Speaker 1: white hole or something crazy. But if you follow general relativity, 151 00:07:54,200 --> 00:07:56,240 Speaker 1: and you know, we think general relativity is correct, although 152 00:07:56,240 --> 00:07:58,280 Speaker 1: we don't think it works inside a black hole. But 153 00:07:58,320 --> 00:08:01,200 Speaker 1: if you're assuming the general relativity inside a black hole, 154 00:08:01,560 --> 00:08:03,960 Speaker 1: then once you fall in, you're moving towards a singularity, 155 00:08:04,040 --> 00:08:06,360 Speaker 1: even if you're dark matter. Interesting. I guess if that's 156 00:08:06,400 --> 00:08:09,440 Speaker 1: the case, then wouldn't we expect most black holes to 157 00:08:09,560 --> 00:08:13,240 Speaker 1: be mostly dark matter? Since there's five times more dark 158 00:08:13,280 --> 00:08:16,160 Speaker 1: matter in the universe and regular matter. It's a great question. 159 00:08:16,280 --> 00:08:19,320 Speaker 1: We don't know what fraction of the stuff inside a 160 00:08:19,360 --> 00:08:22,840 Speaker 1: black hole came from dark matter. But remember that dark 161 00:08:22,840 --> 00:08:25,240 Speaker 1: matter is much more diffuse, it's much more spread out 162 00:08:25,240 --> 00:08:28,160 Speaker 1: through the universe. It doesn't clump as much as normal 163 00:08:28,200 --> 00:08:31,239 Speaker 1: matter because it doesn't have those other kinds of interactions 164 00:08:31,280 --> 00:08:34,959 Speaker 1: like dark matter. These big swirling clouds of stuff that's 165 00:08:34,960 --> 00:08:37,760 Speaker 1: surround our galaxy. But it's harder for dark matter to 166 00:08:37,760 --> 00:08:40,800 Speaker 1: make dense structures because to make dense structures you need 167 00:08:40,880 --> 00:08:43,520 Speaker 1: other kinds of interactions. You need other kind of interactions 168 00:08:43,520 --> 00:08:46,760 Speaker 1: to hold stuff together, like the electromagnetic forces a thing 169 00:08:46,800 --> 00:08:50,240 Speaker 1: that's holding you together, not gravity, and you need those 170 00:08:50,240 --> 00:08:53,559 Speaker 1: interactions to sort of radiate away energy and fall in. 171 00:08:54,120 --> 00:08:56,720 Speaker 1: Like the reason something doesn't just orbit a black hole 172 00:08:56,760 --> 00:08:59,320 Speaker 1: forever is that it loses some of its energy and 173 00:08:59,400 --> 00:09:01,400 Speaker 1: falls in. To do that, you have to be able 174 00:09:01,400 --> 00:09:04,280 Speaker 1: to like radiate off a photon or a z or something, 175 00:09:04,320 --> 00:09:07,400 Speaker 1: and dark matter just can't do that. So dark matter 176 00:09:07,480 --> 00:09:09,760 Speaker 1: is much more spread out. So we don't think that 177 00:09:09,880 --> 00:09:13,200 Speaker 1: dark matter is sort of the primary seed for black holes. 178 00:09:13,240 --> 00:09:16,040 Speaker 1: But some of it must have eventually fallen in, but 179 00:09:16,160 --> 00:09:18,319 Speaker 1: maybe not as much as you might think, because it's 180 00:09:18,360 --> 00:09:20,720 Speaker 1: it's kind of hard for it to fall in. Yeah, precisely. 181 00:09:20,920 --> 00:09:23,040 Speaker 1: And if you take, for example, the volume of our 182 00:09:23,080 --> 00:09:26,439 Speaker 1: solar system, the volume of our solar system is mostly 183 00:09:26,880 --> 00:09:29,240 Speaker 1: filled with normal matter. There's a lot of dark matter 184 00:09:29,280 --> 00:09:31,280 Speaker 1: in there, and there's more dark matter in the universe, 185 00:09:31,559 --> 00:09:34,400 Speaker 1: but in the vicinity of our Solar system, it's mostly 186 00:09:34,480 --> 00:09:37,679 Speaker 1: normal matter. So if our star went black hole, it 187 00:09:37,679 --> 00:09:40,280 Speaker 1: would suck in some of the dark matter that's nearby, 188 00:09:40,360 --> 00:09:42,559 Speaker 1: But most of the matter in our solar system is 189 00:09:42,679 --> 00:09:46,280 Speaker 1: normal matter. And what about neutrinos? Can neutrinos fall into 190 00:09:46,320 --> 00:09:48,720 Speaker 1: a black hole? I guess anything. I think what you're 191 00:09:48,760 --> 00:09:51,680 Speaker 1: saying is that black hole has been space and time, 192 00:09:51,760 --> 00:09:54,000 Speaker 1: so it's more like a space trap rather than just 193 00:09:54,040 --> 00:09:56,439 Speaker 1: a gravity trap. Yeah, exactly, it's a space trap. It 194 00:09:56,480 --> 00:09:59,840 Speaker 1: space is gravity. Gravity is space, and so you're exactly right, 195 00:09:59,880 --> 00:10:02,040 Speaker 1: And anything can fall into a black hole and nothing 196 00:10:02,080 --> 00:10:05,600 Speaker 1: can escape. So the answer to your question, can X 197 00:10:05,679 --> 00:10:08,760 Speaker 1: fall into a black hole? Is always yes? Or any X? 198 00:10:09,240 --> 00:10:11,840 Speaker 1: Can the letter X daniel as a concept of fall 199 00:10:11,920 --> 00:10:15,520 Speaker 1: inside of a black hole? Oh? Man, can philosophical ideas 200 00:10:15,800 --> 00:10:18,920 Speaker 1: fall into a black hole? Well? There is this crazy 201 00:10:19,000 --> 00:10:22,680 Speaker 1: theory that information has mass, and you know that's never 202 00:10:22,720 --> 00:10:25,360 Speaker 1: really been proven, but so perhaps, yeah, you come up 203 00:10:25,360 --> 00:10:27,680 Speaker 1: with a crazenough idea that your head becomes a black hole, 204 00:10:27,720 --> 00:10:29,760 Speaker 1: and you were thinking about the letter X, then yeah, 205 00:10:30,400 --> 00:10:33,679 Speaker 1: Well I believe we renamed black holes to space traps. 206 00:10:34,000 --> 00:10:37,640 Speaker 1: I feel like that's more accurate and more descriptive. All right, 207 00:10:37,679 --> 00:10:39,600 Speaker 1: well we'll start using that on the podcast from now 208 00:10:39,600 --> 00:10:44,160 Speaker 1: on and we'll see if it catches on your space trap. 209 00:10:45,559 --> 00:10:48,960 Speaker 1: All right, well, I think that answers the questions forms contraras. 210 00:10:49,080 --> 00:10:51,800 Speaker 1: Thank you for asking the question. Our next question is 211 00:10:51,840 --> 00:10:56,680 Speaker 1: about the universe small topic and whether it's stretching and expanding. 212 00:10:57,080 --> 00:11:01,640 Speaker 1: So Steve slopeck as, if the universe is stretching and expanding, 213 00:11:01,920 --> 00:11:05,440 Speaker 1: what's it expanding into? Now you said, this is another 214 00:11:05,480 --> 00:11:07,640 Speaker 1: common question we get. This is a question we get 215 00:11:07,679 --> 00:11:10,160 Speaker 1: like once a week. People are hearing about how the 216 00:11:10,240 --> 00:11:13,440 Speaker 1: universe is getting bigger, and they're wondering, like, if the 217 00:11:13,520 --> 00:11:16,839 Speaker 1: universe is everything, how can it be getting bigger. Doesn't 218 00:11:16,840 --> 00:11:19,400 Speaker 1: that mean it's sitting inside something else that's holding it 219 00:11:19,440 --> 00:11:22,360 Speaker 1: that it's now like filling up. I think people are imagining, like, 220 00:11:22,760 --> 00:11:26,200 Speaker 1: you know, a blob of molecules inside an empty room 221 00:11:26,280 --> 00:11:28,760 Speaker 1: spreading out to sort of fill out all those corners. 222 00:11:28,840 --> 00:11:32,520 Speaker 1: I have that question, and it's an amazing question. But 223 00:11:32,600 --> 00:11:35,080 Speaker 1: the answer is no, that the universe is not expanding 224 00:11:35,120 --> 00:11:39,040 Speaker 1: into anything, because the expansion is not like relative to 225 00:11:39,120 --> 00:11:44,760 Speaker 1: some outside external space or metric right, The expansion is intrinsic. 226 00:11:45,120 --> 00:11:49,160 Speaker 1: It means that distances between points are getting larger. So 227 00:11:49,200 --> 00:11:52,360 Speaker 1: we don't have our space, you know, our three dimensional 228 00:11:52,440 --> 00:11:56,280 Speaker 1: space sitting inside some other box. It's just stretching, it's 229 00:11:56,320 --> 00:11:59,680 Speaker 1: creating new space between existing points. Well, I feel like 230 00:11:59,679 --> 00:12:02,240 Speaker 1: what you're saying is that there's nothing outside of space. 231 00:12:02,440 --> 00:12:06,560 Speaker 1: But isn't nothing something? There isn't anything outside of space, 232 00:12:06,600 --> 00:12:08,760 Speaker 1: so I avoid saying the word nothing. What do you 233 00:12:08,800 --> 00:12:11,199 Speaker 1: mean What makes you uncomfortable about the word nothing? Well, 234 00:12:11,440 --> 00:12:13,280 Speaker 1: it depends what you mean by space. I mean the 235 00:12:13,320 --> 00:12:17,520 Speaker 1: origin of space was sort of like the backdrop on 236 00:12:17,600 --> 00:12:21,320 Speaker 1: which things happen, you know, you like define distances and 237 00:12:21,360 --> 00:12:23,640 Speaker 1: you could have empty space and then stuff in it. 238 00:12:24,000 --> 00:12:26,960 Speaker 1: Sort of the origin of the concept of space originally. 239 00:12:27,280 --> 00:12:29,080 Speaker 1: But now we know that space is not like that. 240 00:12:29,120 --> 00:12:32,840 Speaker 1: Space is dynamic. It's flexible. It can shimmer and wiggle 241 00:12:32,920 --> 00:12:36,680 Speaker 1: and stretch and grow and bend. Right, But you're tempted 242 00:12:37,000 --> 00:12:40,679 Speaker 1: to put it in some now static, larger space. Right, 243 00:12:40,679 --> 00:12:44,240 Speaker 1: there's nothing on which this like goo of space actually sits. 244 00:12:44,679 --> 00:12:46,760 Speaker 1: But we don't have any evidence that that exists. We 245 00:12:46,760 --> 00:12:50,840 Speaker 1: don't know that there's some other external, true deep meta 246 00:12:50,880 --> 00:12:54,480 Speaker 1: space in which our space exists. It seems like all 247 00:12:54,520 --> 00:12:58,080 Speaker 1: the math is consistent with just our space bending relative 248 00:12:58,160 --> 00:13:01,320 Speaker 1: to itself. But I guess the question is if we 249 00:13:01,400 --> 00:13:05,199 Speaker 1: can expand I think maybe what trips people up is like, 250 00:13:05,240 --> 00:13:09,000 Speaker 1: what are we expanding into? If we're expanding into something, 251 00:13:09,640 --> 00:13:11,959 Speaker 1: then you must be able to measure it, And so 252 00:13:12,280 --> 00:13:15,280 Speaker 1: wouldn't it be like empty space kind of right that 253 00:13:15,360 --> 00:13:18,160 Speaker 1: you can measure. I think the confusion there is expansion, right. 254 00:13:18,160 --> 00:13:22,520 Speaker 1: We're not expanding into anything, We're expanding relative to ourselves. 255 00:13:22,559 --> 00:13:25,880 Speaker 1: So if you have two points in space and you wait, 256 00:13:26,080 --> 00:13:28,920 Speaker 1: you will notice, thanks to dark energy and the expansion 257 00:13:28,920 --> 00:13:31,319 Speaker 1: of the universe, that they are getting further and further apart. 258 00:13:31,800 --> 00:13:33,680 Speaker 1: So you can that's how you measure it. You don't 259 00:13:33,840 --> 00:13:35,920 Speaker 1: step outside of the universe and be like, hey, the 260 00:13:36,000 --> 00:13:39,360 Speaker 1: universe is fourteen inches wide and last year was thirteen 261 00:13:39,640 --> 00:13:42,560 Speaker 1: Look how much it's grown. You measure the points between 262 00:13:42,679 --> 00:13:44,440 Speaker 1: things in space because that's all you can do. You 263 00:13:44,440 --> 00:13:47,280 Speaker 1: can't step outside of space. It doesn't even really mean anything. 264 00:13:48,520 --> 00:13:50,679 Speaker 1: Maybe the way to think about it is that the 265 00:13:50,679 --> 00:13:53,880 Speaker 1: space is not growing. It's almost like it's stayed the 266 00:13:53,920 --> 00:13:56,920 Speaker 1: same size, but we're shrinking inside of it. You know. Actually, 267 00:13:57,080 --> 00:13:59,400 Speaker 1: Dan Hooper, who we've had on the program, a cosmologist, 268 00:13:59,600 --> 00:14:01,560 Speaker 1: likes to make that point that you can't actually tell 269 00:14:01,600 --> 00:14:05,240 Speaker 1: the difference between the expansion of space and the shrinking 270 00:14:05,280 --> 00:14:09,560 Speaker 1: of stuff that looks exactly the same. There you go. 271 00:14:10,040 --> 00:14:13,280 Speaker 1: So maybe that will help people from reading confused, because 272 00:14:13,600 --> 00:14:15,160 Speaker 1: you know, sort of just think about it more like 273 00:14:15,360 --> 00:14:17,640 Speaker 1: we're the same, space is the same, but we're shrinking. 274 00:14:18,520 --> 00:14:20,560 Speaker 1: I mean that invites lots of other questions, like if 275 00:14:20,600 --> 00:14:22,560 Speaker 1: I eat so many tacos, how could I possibly be 276 00:14:22,600 --> 00:14:26,240 Speaker 1: shrinking because the tacas are shrinking. Yeah, that's a that's 277 00:14:26,280 --> 00:14:27,880 Speaker 1: another way to think about it. And you know, remember 278 00:14:27,880 --> 00:14:31,320 Speaker 1: that we don't understand why the universe is expanding. It's 279 00:14:31,320 --> 00:14:34,040 Speaker 1: not something that we understand and can make sense of. 280 00:14:34,120 --> 00:14:36,640 Speaker 1: We don't know why it's happening, why it started happening 281 00:14:36,640 --> 00:14:39,880 Speaker 1: five billion years ago, whether it will continue to happen. 282 00:14:40,200 --> 00:14:43,520 Speaker 1: All we have are these observations that distances between things 283 00:14:43,520 --> 00:14:46,760 Speaker 1: in space are expanding and expanding at an accelerating rate. 284 00:14:47,160 --> 00:14:49,080 Speaker 1: So it's something we observe, and you have to just 285 00:14:49,360 --> 00:14:51,880 Speaker 1: go back to the root experiment, like what is it 286 00:14:51,920 --> 00:14:54,840 Speaker 1: we actually see, rather than you're trying to get tangled 287 00:14:54,920 --> 00:14:58,120 Speaker 1: up in the various theories of cosmological constants. It's almost 288 00:14:58,160 --> 00:15:00,200 Speaker 1: like the opposite of what happens when you grow up. 289 00:15:00,560 --> 00:15:03,400 Speaker 1: Like I feel like when you're a kid, distances seemed huge, 290 00:15:03,800 --> 00:15:07,240 Speaker 1: like sitting in the car for an hour, it takes forever. 291 00:15:07,920 --> 00:15:10,240 Speaker 1: But when you grow up and you're an adult, distance 292 00:15:10,280 --> 00:15:13,120 Speaker 1: this kind of shrink no way, right, like sitting in 293 00:15:13,120 --> 00:15:16,600 Speaker 1: an hour for I think that tour doesn't seem long 294 00:15:16,720 --> 00:15:19,480 Speaker 1: enough actually, and so it's kind of the opposite of that. 295 00:15:19,520 --> 00:15:22,320 Speaker 1: It's almost like relationship that matter has to space is changing. 296 00:15:22,320 --> 00:15:25,240 Speaker 1: And that's what this does mean by its expansion of 297 00:15:25,280 --> 00:15:27,840 Speaker 1: the universe. You're staying in the universe is just growing 298 00:15:27,920 --> 00:15:30,240 Speaker 1: up an eventual it's gonna have a midlife crisis, not 299 00:15:30,440 --> 00:15:34,760 Speaker 1: going down. It's pulling Benjamin button. Do you think for 300 00:15:34,800 --> 00:15:37,560 Speaker 1: the universe, like now a billion years just like flits 301 00:15:37,600 --> 00:15:39,520 Speaker 1: by in a moment, whereas when it was a kid 302 00:15:39,680 --> 00:15:43,160 Speaker 1: it took forever. Yeah, kind of in a way, right, yeah, yeah, 303 00:15:43,160 --> 00:15:47,040 Speaker 1: maybe that that explains time dilation. Man, Man relativity is 304 00:15:47,120 --> 00:15:49,800 Speaker 1: just about getting mature. I'll take the Nobel price right now, 305 00:15:51,520 --> 00:15:55,040 Speaker 1: I'll buy you a taco Alright. We have a lot 306 00:15:55,120 --> 00:15:57,920 Speaker 1: more of these most common questions that we get through 307 00:15:57,960 --> 00:16:14,560 Speaker 1: the inbox, but first let's take a quick break. All right. 308 00:16:14,600 --> 00:16:18,760 Speaker 1: I know we're answering our most common questions that we 309 00:16:18,840 --> 00:16:24,560 Speaker 1: get through the inbox and through Twitter, and we've answered 310 00:16:24,640 --> 00:16:27,680 Speaker 1: questions about black holes and the universe expanding, and we 311 00:16:27,720 --> 00:16:30,120 Speaker 1: also have questions about particles, which is kind of your 312 00:16:30,800 --> 00:16:35,000 Speaker 1: field of expertise particles and tacos. Don't forget, I'm quite 313 00:16:35,040 --> 00:16:40,160 Speaker 1: an expert talca particle, tacas or taco particles. Let's talk 314 00:16:40,280 --> 00:16:45,640 Speaker 1: about it. Is that what a takito is? That's right, 315 00:16:45,840 --> 00:16:49,000 Speaker 1: that's when your tacos exchanged particles with your friends takings. Well, 316 00:16:49,160 --> 00:16:52,480 Speaker 1: that's not that's a no no these days, but that's right. 317 00:16:52,680 --> 00:16:54,880 Speaker 1: Stay safe out there people, all right. So our next 318 00:16:54,920 --> 00:16:59,680 Speaker 1: question is asking about the charge of particles. For example, 319 00:16:59,760 --> 00:17:02,800 Speaker 1: me Brown asked, I was wondering how particles could be 320 00:17:02,880 --> 00:17:06,680 Speaker 1: charged and what that even means? Exclamation point question mark. 321 00:17:06,760 --> 00:17:09,520 Speaker 1: Oh man, I love this question because I have this 322 00:17:09,640 --> 00:17:12,920 Speaker 1: same question and we still don't really know what particle 323 00:17:13,040 --> 00:17:15,640 Speaker 1: charge is. It's very confusing. Yeah, I like how she asked, 324 00:17:15,640 --> 00:17:20,119 Speaker 1: what does that even mean? It's wonderful because you know, 325 00:17:20,280 --> 00:17:23,080 Speaker 1: it's something where that's very familiar. People think about charge 326 00:17:23,119 --> 00:17:25,800 Speaker 1: and electric charge and familiar with lightning and whatever. But 327 00:17:25,920 --> 00:17:28,400 Speaker 1: down at the particle level, like what does it mean 328 00:17:28,440 --> 00:17:31,240 Speaker 1: for a particle to have electric charge? Like is it 329 00:17:31,400 --> 00:17:34,520 Speaker 1: carrying something? Is they're charge like stuffed into it somewhere. 330 00:17:34,800 --> 00:17:36,600 Speaker 1: Why does some of them have it some of them don't. 331 00:17:36,840 --> 00:17:39,520 Speaker 1: It's a great deep question, Yeah, because I guess she's 332 00:17:39,520 --> 00:17:42,840 Speaker 1: really wondering, like because it seems arbitrary, like a particle 333 00:17:42,960 --> 00:17:44,720 Speaker 1: has charged or it doesn't have charge, or it has 334 00:17:44,720 --> 00:17:47,679 Speaker 1: positive charge, or it has a color charge. You know 335 00:17:47,840 --> 00:17:51,159 Speaker 1: what determines that and why do they have it? And 336 00:17:51,200 --> 00:17:53,359 Speaker 1: the answer is that we don't know, and we have 337 00:17:53,440 --> 00:17:55,800 Speaker 1: to just sort of root ourselves and what we have seen. 338 00:17:55,960 --> 00:17:58,840 Speaker 1: Remember that all of these ideas about particle physics and 339 00:17:58,840 --> 00:18:01,880 Speaker 1: the universe they come out of experiments that we've done, 340 00:18:02,040 --> 00:18:04,760 Speaker 1: things we've seen, and that we're trying to describe about 341 00:18:04,800 --> 00:18:07,320 Speaker 1: the universe. We don't always understand what's going on, and 342 00:18:07,320 --> 00:18:10,000 Speaker 1: we're just sort of trying to build a structure that 343 00:18:10,119 --> 00:18:13,239 Speaker 1: let's it all hang together. And for particle charge, the 344 00:18:13,320 --> 00:18:15,960 Speaker 1: root thing that we see is that some little bits 345 00:18:15,960 --> 00:18:19,200 Speaker 1: of matter, some particles, are affected by electric fields and 346 00:18:19,280 --> 00:18:22,840 Speaker 1: magnetic fields. Like you put electrons through an electric field, 347 00:18:23,080 --> 00:18:26,000 Speaker 1: they will get accelerated. You put other particles, you know, 348 00:18:26,040 --> 00:18:28,640 Speaker 1: particles that don't have electric charge through an electric field, 349 00:18:28,760 --> 00:18:31,560 Speaker 1: they don't get accelerated. That's what it means to have 350 00:18:31,680 --> 00:18:34,280 Speaker 1: electric charge. That's the root thing. We've seen that some 351 00:18:34,359 --> 00:18:37,880 Speaker 1: particles are pulled by electric fields and some particles are not. 352 00:18:38,160 --> 00:18:40,760 Speaker 1: That's really what a charge means. So you're saying it's 353 00:18:40,760 --> 00:18:43,760 Speaker 1: part of a philosophical answer, like they have charged because 354 00:18:43,800 --> 00:18:45,560 Speaker 1: we've seen them. I have charged, or at least Daniel 355 00:18:45,560 --> 00:18:47,960 Speaker 1: has seen them. They have charged. Yeah, Well, we see 356 00:18:48,000 --> 00:18:50,320 Speaker 1: that some particles are affected by electric fields, and so 357 00:18:50,400 --> 00:18:53,280 Speaker 1: we say, all right, let's say that those particles are different, 358 00:18:53,280 --> 00:18:56,520 Speaker 1: and we'll create this idea of charge, and we'll use 359 00:18:56,560 --> 00:18:59,640 Speaker 1: that as a description to say which particles are affected 360 00:18:59,640 --> 00:19:01,840 Speaker 1: by elect fields and which ones are not. And then 361 00:19:01,840 --> 00:19:04,280 Speaker 1: we'll look for patterns, and we'll look for trends, and 362 00:19:04,320 --> 00:19:07,280 Speaker 1: we'll look for symmetries, and we'll try to understand that 363 00:19:07,359 --> 00:19:11,560 Speaker 1: more deeply. But fundamentally, it's just really a label for 364 00:19:11,600 --> 00:19:14,560 Speaker 1: the things we've observed. Now, I wonder if what she's 365 00:19:14,560 --> 00:19:18,040 Speaker 1: trying to get at is whether charge is a property 366 00:19:18,160 --> 00:19:22,080 Speaker 1: of particles or the field that make up the particles, 367 00:19:22,200 --> 00:19:23,960 Speaker 1: You know what I mean, Like Is it something that 368 00:19:24,280 --> 00:19:27,240 Speaker 1: gets a sign when the particle pops up, or is 369 00:19:27,280 --> 00:19:29,879 Speaker 1: it something that's just like a property of the field 370 00:19:29,960 --> 00:19:33,240 Speaker 1: that they're part of. Yeah, that's a great question. Mathematically, 371 00:19:33,600 --> 00:19:36,240 Speaker 1: we sort of put it in the middle, like we 372 00:19:36,280 --> 00:19:39,840 Speaker 1: think of particles, you know, as fields. Mathematically we think 373 00:19:39,880 --> 00:19:42,160 Speaker 1: of it's sort of in the middle, like we write 374 00:19:42,160 --> 00:19:44,959 Speaker 1: these things into our theories. And we said that the 375 00:19:45,040 --> 00:19:48,760 Speaker 1: charge is the thing that connects the field with the particle. 376 00:19:49,359 --> 00:19:53,240 Speaker 1: So for example, the photon field only interacts with things 377 00:19:53,280 --> 00:19:56,360 Speaker 1: that have electric charge, and so it's really right there 378 00:19:56,359 --> 00:19:58,440 Speaker 1: in between is how the two talk to each other. 379 00:19:58,440 --> 00:20:00,640 Speaker 1: It's the thing that lets them talk to each other, 380 00:20:00,880 --> 00:20:03,800 Speaker 1: the field and the particle. So it's sort of a 381 00:20:03,800 --> 00:20:06,879 Speaker 1: property of their interaction. Oh, I see, it's kind of 382 00:20:06,960 --> 00:20:10,840 Speaker 1: maybe a property of both, kind of what you're saying, Yeah, exactly. 383 00:20:11,320 --> 00:20:14,400 Speaker 1: And you know, we have noticed some amazing interesting things 384 00:20:14,440 --> 00:20:17,960 Speaker 1: about charge, like charge is conserved. You know, you can't 385 00:20:18,080 --> 00:20:21,719 Speaker 1: create it or destroy it. No matter how many particles 386 00:20:21,800 --> 00:20:25,639 Speaker 1: you create or destroy, the total charge is unchanged. And 387 00:20:25,680 --> 00:20:27,919 Speaker 1: that tells us that it must be something interesting and 388 00:20:27,920 --> 00:20:30,480 Speaker 1: fundamental to the universe, sort of like energy. We think 389 00:20:30,600 --> 00:20:34,000 Speaker 1: energy isn't changed in these interactions, and so that tells 390 00:20:34,040 --> 00:20:36,879 Speaker 1: us it might be something deep, that it's connected somehow 391 00:20:37,240 --> 00:20:40,480 Speaker 1: to something really deep about the universe and particles and fields. 392 00:20:40,640 --> 00:20:42,959 Speaker 1: But the truth is we don't exactly know what. Like 393 00:20:43,000 --> 00:20:44,680 Speaker 1: it could be a thing itself, you know what I mean, 394 00:20:44,720 --> 00:20:46,920 Speaker 1: Like it's like something that's being conserved. So it's kind 395 00:20:46,960 --> 00:20:49,040 Speaker 1: of like something that can be quantified in a way. 396 00:20:49,280 --> 00:20:52,840 Speaker 1: It can definitely can be quantified, yeah, absolutely, And you know, 397 00:20:52,960 --> 00:20:55,720 Speaker 1: there are other kinds of charge also, right, as you 398 00:20:55,720 --> 00:20:59,120 Speaker 1: mentioned earlier, Like the strong force has its own equivalent 399 00:20:59,280 --> 00:21:02,040 Speaker 1: of charge. We call it color to be confusing and 400 00:21:02,080 --> 00:21:05,159 Speaker 1: attempting to be poetic, and it has a lot of 401 00:21:05,240 --> 00:21:08,480 Speaker 1: similar properties to electric charge, and that some particles have it, 402 00:21:08,640 --> 00:21:11,639 Speaker 1: some particles don't. And there's one for the weak force. 403 00:21:11,920 --> 00:21:14,520 Speaker 1: Some particles have it, some particles don't. Whi's one of 404 00:21:14,600 --> 00:21:17,480 Speaker 1: the deep mysteries of physics is of why some particles 405 00:21:17,520 --> 00:21:19,800 Speaker 1: have some of these charges and don't have other charges. 406 00:21:19,920 --> 00:21:22,080 Speaker 1: It's very confusing, and what we're trying to do is 407 00:21:22,119 --> 00:21:25,760 Speaker 1: make a unified vision understand how this all shook out 408 00:21:25,800 --> 00:21:27,600 Speaker 1: and why it's this way and not the other way. 409 00:21:27,640 --> 00:21:29,720 Speaker 1: But the truth is, we just really don't know, it 410 00:21:29,760 --> 00:21:31,720 Speaker 1: sounds like it's almost like that the language of the 411 00:21:31,800 --> 00:21:35,360 Speaker 1: universe is this charge, you know. Yeah, like some particles 412 00:21:35,359 --> 00:21:38,080 Speaker 1: speak like romannitism, so some don't, and that's how they 413 00:21:38,080 --> 00:21:40,560 Speaker 1: interact with the fields around them and other particles. Yeah, 414 00:21:40,560 --> 00:21:42,800 Speaker 1: but why right, Why do some particles feel this and 415 00:21:43,119 --> 00:21:45,199 Speaker 1: others don't? How did that happen? And what does that 416 00:21:45,240 --> 00:21:48,640 Speaker 1: even mean? What does that even mean? Question mark? Exclamation point. 417 00:21:49,040 --> 00:21:50,919 Speaker 1: That's like the reason I got into physics because I 418 00:21:50,920 --> 00:21:53,679 Speaker 1: love asking that question what does that even mean? You know, 419 00:21:53,800 --> 00:21:56,879 Speaker 1: we want to gather together these weird experiments we've seen 420 00:21:57,080 --> 00:21:59,480 Speaker 1: and get some sort of deep understanding, appeal back a 421 00:21:59,560 --> 00:22:02,000 Speaker 1: layer of reality, and reveal the way the universe like 422 00:22:02,240 --> 00:22:06,119 Speaker 1: actually works. Man, you guys used exclamation points and question 423 00:22:06,119 --> 00:22:09,000 Speaker 1: marks at the same time in your physics papers, only 424 00:22:09,040 --> 00:22:13,240 Speaker 1: in the best ones. All right, thanks for that question. 425 00:22:13,600 --> 00:22:16,760 Speaker 1: Our next question is another common question that we get, 426 00:22:16,800 --> 00:22:19,960 Speaker 1: and this one in particular came from Roger Grenna, and 427 00:22:20,000 --> 00:22:22,560 Speaker 1: the question goes, how do particles which I understand, how 428 00:22:22,760 --> 00:22:26,880 Speaker 1: zero volume make up matter? So that stuff has volume. 429 00:22:26,960 --> 00:22:30,720 Speaker 1: That's a great question. If particles have no volume, how 430 00:22:30,720 --> 00:22:32,679 Speaker 1: can we have volume? If the recipe for making of 431 00:22:32,760 --> 00:22:34,679 Speaker 1: you is a bunch of particles and that each have 432 00:22:34,800 --> 00:22:37,320 Speaker 1: zero volume, then why isn't your volume just the sum 433 00:22:37,520 --> 00:22:40,280 Speaker 1: of a bunch of zeros which is zero? Right? Right? Yeah? 434 00:22:40,760 --> 00:22:44,359 Speaker 1: Or I guess maybe is my volume kind of an illusion? 435 00:22:44,480 --> 00:22:46,640 Speaker 1: Kind of like if if you drill down and there's 436 00:22:46,680 --> 00:22:49,280 Speaker 1: no real volume to any of my particles, does that 437 00:22:49,320 --> 00:22:55,080 Speaker 1: mean that I am also devoid of volume? I'll avoid 438 00:22:55,080 --> 00:22:58,440 Speaker 1: a lot of bad jokes there. But if I eat 439 00:22:58,440 --> 00:23:03,200 Speaker 1: a taco, Daniel, how does that effect my volume? Where 440 00:23:03,200 --> 00:23:06,119 Speaker 1: does that taco actually go? Well? And there's lots of 441 00:23:06,160 --> 00:23:09,120 Speaker 1: ways to attack this problem, and the most philosophicals to ask, 442 00:23:09,200 --> 00:23:11,639 Speaker 1: like what do you mean by volume? And we had 443 00:23:11,680 --> 00:23:14,960 Speaker 1: a whole podcast episode about like how small are particles? 444 00:23:15,040 --> 00:23:17,760 Speaker 1: What do we mean by their size? Etcetera, etcetera. But 445 00:23:17,800 --> 00:23:19,639 Speaker 1: that's a whole rabbit hole. Let's put that aside and 446 00:23:19,680 --> 00:23:23,000 Speaker 1: say particles are points. Let's assume for now the particles 447 00:23:23,040 --> 00:23:25,640 Speaker 1: actually have zero volume. Right, it's a good point. Yeah, 448 00:23:27,080 --> 00:23:29,000 Speaker 1: So to try to get to the point here, the 449 00:23:29,040 --> 00:23:32,000 Speaker 1: idea is that you can build something with non zero 450 00:23:32,119 --> 00:23:35,960 Speaker 1: volume out of particles that have zero volume if you 451 00:23:36,040 --> 00:23:38,760 Speaker 1: have a way to space them. There's something keeping them 452 00:23:38,800 --> 00:23:42,240 Speaker 1: from overlapping from crunching on top of each other, and 453 00:23:42,359 --> 00:23:45,600 Speaker 1: you do, and they have forces. They have electric forces, 454 00:23:45,600 --> 00:23:48,000 Speaker 1: for example, And so the reason that, like when you 455 00:23:48,000 --> 00:23:50,800 Speaker 1: build a molecule, the atoms don't just lie on top 456 00:23:50,840 --> 00:23:54,080 Speaker 1: of each other is that there are electrons circling those 457 00:23:54,119 --> 00:23:57,800 Speaker 1: atoms that keep the nuclei apart, and the nuclei are 458 00:23:57,880 --> 00:24:00,520 Speaker 1: positively charged and they keep each other apart. So there 459 00:24:00,520 --> 00:24:02,600 Speaker 1: are forces there that creates sort of like a spacing, 460 00:24:02,680 --> 00:24:05,919 Speaker 1: like a lattice that keeps everything from collapsing into the 461 00:24:06,000 --> 00:24:08,800 Speaker 1: tiniest dunk. I guess that, yeah, you're ready. It does 462 00:24:08,840 --> 00:24:11,480 Speaker 1: depend on what you mean by volume, because if by 463 00:24:11,560 --> 00:24:14,840 Speaker 1: volume mean like when something is there and it's not there, 464 00:24:15,480 --> 00:24:19,720 Speaker 1: then particles almost have zero volume. But they're also kind 465 00:24:19,720 --> 00:24:21,920 Speaker 1: of infinite volume, right because you can feel a particle 466 00:24:22,080 --> 00:24:25,359 Speaker 1: all the way across the galaxy. Technically, yeah, yeah, technically, 467 00:24:25,840 --> 00:24:28,240 Speaker 1: And so you could also say that if you're made 468 00:24:28,240 --> 00:24:31,840 Speaker 1: of zero volume particles, even if they have spacing between them, 469 00:24:31,960 --> 00:24:33,960 Speaker 1: then your real volume is still just the sum of 470 00:24:34,000 --> 00:24:36,480 Speaker 1: all those zeros, even though they're distributed into sort of 471 00:24:36,480 --> 00:24:39,040 Speaker 1: a cloud. And you guy, it's like, well, where do 472 00:24:39,119 --> 00:24:41,360 Speaker 1: you stop if you're made of a bunch of particles 473 00:24:41,359 --> 00:24:43,159 Speaker 1: that are spaced apart, where do you stop. Do you 474 00:24:43,200 --> 00:24:46,360 Speaker 1: stop at the edge of the most like right most particle, 475 00:24:46,920 --> 00:24:49,439 Speaker 1: or where it pushes back, as you were saying, like 476 00:24:49,440 --> 00:24:52,840 Speaker 1: where it feels something and and where it pushes back. 477 00:24:52,960 --> 00:24:55,080 Speaker 1: Is also not very satisfying because then it depends on 478 00:24:55,280 --> 00:24:58,320 Speaker 1: what you're pushing with or against, yeah, or against. If 479 00:24:58,359 --> 00:25:01,000 Speaker 1: you push against dark matter, matter will pass right through 480 00:25:01,040 --> 00:25:04,240 Speaker 1: you like you're not there. If you push against neutrinos, 481 00:25:04,480 --> 00:25:07,240 Speaker 1: it will very lightly touch you. If you push against 482 00:25:07,280 --> 00:25:09,800 Speaker 1: you know, a regular object like a stick, then you're 483 00:25:09,840 --> 00:25:12,520 Speaker 1: pushing against the electromagnetic forces. So it depends on the 484 00:25:12,640 --> 00:25:15,200 Speaker 1: kind of thing you're probing with. So it's not really 485 00:25:15,320 --> 00:25:18,160 Speaker 1: very well defined. But if you just say, like, hey, 486 00:25:18,240 --> 00:25:21,640 Speaker 1: you can make a cloud out of non zero particles 487 00:25:21,640 --> 00:25:24,760 Speaker 1: that keep their spacing because of the forces between them, 488 00:25:24,880 --> 00:25:27,040 Speaker 1: then you get a pretty good sense for why you 489 00:25:27,080 --> 00:25:30,800 Speaker 1: aren't just a tiny dot. Yeah, I guess maybe, like 490 00:25:30,880 --> 00:25:33,040 Speaker 1: if you go by effect and technically we all have 491 00:25:33,080 --> 00:25:36,400 Speaker 1: infinite volume, like you know, if someone across the universe 492 00:25:36,640 --> 00:25:38,800 Speaker 1: feels me in a way and feels the forces that 493 00:25:38,920 --> 00:25:43,399 Speaker 1: like particles exert. But if you talk, if you call volume, 494 00:25:43,480 --> 00:25:47,720 Speaker 1: like where are the particles center that make up rhead? 495 00:25:47,800 --> 00:25:50,040 Speaker 1: Then because I have more than one, then you can 496 00:25:50,040 --> 00:25:53,600 Speaker 1: sort of define a range of space like a volume 497 00:25:53,640 --> 00:25:56,719 Speaker 1: of space, and that's maybe that's volume. Yeah, and so 498 00:25:56,800 --> 00:25:59,840 Speaker 1: it's a slippery topic volume, you know. Microscopically, it does 499 00:26:00,200 --> 00:26:02,680 Speaker 1: really have a great analog to the way we think 500 00:26:02,680 --> 00:26:05,880 Speaker 1: about it, like intuitively and macroscopically. And this is something 501 00:26:05,920 --> 00:26:07,840 Speaker 1: we struggle with all the time when we take our 502 00:26:08,280 --> 00:26:13,320 Speaker 1: common knowledge about how things work mass, volume, velocity, you know, time, 503 00:26:13,400 --> 00:26:15,480 Speaker 1: and we try to apply them to the microscopic where 504 00:26:15,480 --> 00:26:17,960 Speaker 1: the rules are really just totally different, and sometimes the 505 00:26:18,040 --> 00:26:20,960 Speaker 1: very ideas break down and don't really have a great analog. 506 00:26:22,119 --> 00:26:24,960 Speaker 1: All right, mind bending question. All right. Our next question 507 00:26:25,560 --> 00:26:28,080 Speaker 1: from our most common question pile is a bit of 508 00:26:28,200 --> 00:26:32,120 Speaker 1: a career question, and I'm curious that's why you get 509 00:26:32,160 --> 00:26:35,200 Speaker 1: this a lot. So the question goes, I've always loved 510 00:26:35,200 --> 00:26:38,199 Speaker 1: physics but studied something else. Is it too late for 511 00:26:38,200 --> 00:26:42,040 Speaker 1: me to learn physics for real? I'd like to for real. 512 00:26:42,080 --> 00:26:45,200 Speaker 1: At the end, we do get this question a lot, 513 00:26:45,280 --> 00:26:48,200 Speaker 1: and I think that that's because our podcast has attractive 514 00:26:48,240 --> 00:26:51,080 Speaker 1: folks who are really interested in questions of the universe. 515 00:26:51,119 --> 00:26:54,560 Speaker 1: And have a passion for understanding these things, but because 516 00:26:54,560 --> 00:26:56,800 Speaker 1: of whatever happened to them in life, didn't end up 517 00:26:56,840 --> 00:26:59,800 Speaker 1: studying physics. They studied computers or ended up in something 518 00:26:59,800 --> 00:27:02,560 Speaker 1: else in their life. And maybe this has reignited their 519 00:27:02,600 --> 00:27:04,600 Speaker 1: interest a little bit, and they're wondering, like, is the 520 00:27:04,640 --> 00:27:06,720 Speaker 1: door closed? Is there still a path for me to 521 00:27:06,800 --> 00:27:09,159 Speaker 1: like go back to school and get a degree in 522 00:27:09,200 --> 00:27:13,119 Speaker 1: physics and actually do physics for real? Yeah? And the 523 00:27:13,160 --> 00:27:18,200 Speaker 1: answer is no, Right, anyone can study physics even for real. Yeah, 524 00:27:18,200 --> 00:27:21,080 Speaker 1: it's never too late, And it depends on your life 525 00:27:21,080 --> 00:27:23,800 Speaker 1: and your personal situation, of course, and whether you have 526 00:27:23,880 --> 00:27:26,880 Speaker 1: the time available in the financial means to go back 527 00:27:26,920 --> 00:27:30,280 Speaker 1: to school. But there are lots of paths back into physics. 528 00:27:30,640 --> 00:27:32,480 Speaker 1: And something I think that a lot of people don't 529 00:27:32,600 --> 00:27:36,480 Speaker 1: understand is that you don't need like a formal physics 530 00:27:36,640 --> 00:27:41,040 Speaker 1: undergraduate degree from a fancy university to get back into physics. 531 00:27:41,440 --> 00:27:43,680 Speaker 1: I can tell the story of somebody here in Irvine 532 00:27:43,680 --> 00:27:46,560 Speaker 1: who was always interested in physics but ended up in 533 00:27:46,680 --> 00:27:50,080 Speaker 1: computers and working in software for fifteen years and then 534 00:27:50,200 --> 00:27:52,000 Speaker 1: came to me one day to my office and said, look, 535 00:27:52,200 --> 00:27:54,400 Speaker 1: I want to get back into physics. What can I do, 536 00:27:54,920 --> 00:27:57,040 Speaker 1: And he just ended up taking a bunch of classes 537 00:27:57,080 --> 00:27:59,760 Speaker 1: at u C I not as an enrolled student, just 538 00:27:59,800 --> 00:28:02,680 Speaker 1: like taking classes, which you can do at most universities 539 00:28:03,000 --> 00:28:05,280 Speaker 1: without getting into it like a degree program. You don't 540 00:28:05,280 --> 00:28:07,880 Speaker 1: need to apply to become a freshman. You just take 541 00:28:07,920 --> 00:28:10,680 Speaker 1: the classes you need. Then you can apply to graduate 542 00:28:10,720 --> 00:28:13,080 Speaker 1: schools and you can say, look, I've done these courses, 543 00:28:13,280 --> 00:28:16,200 Speaker 1: I've got reasonable grades in them. And that student, for example, 544 00:28:16,440 --> 00:28:19,480 Speaker 1: he's now a grad student at an Ivy League university 545 00:28:19,560 --> 00:28:23,480 Speaker 1: in physics. And so it's totally possible. If you have 546 00:28:23,600 --> 00:28:25,760 Speaker 1: the interest and you can do it in your spare 547 00:28:25,800 --> 00:28:28,440 Speaker 1: time and sort of build up the basic knowledge you need, 548 00:28:28,760 --> 00:28:31,119 Speaker 1: then you can jump right back in and the doors 549 00:28:31,160 --> 00:28:33,159 Speaker 1: can still be open. Yeah, you can still be like 550 00:28:33,680 --> 00:28:36,280 Speaker 1: a physicist at any point in your life. I mean, 551 00:28:36,520 --> 00:28:38,720 Speaker 1: people change careers all the time, And I mean I 552 00:28:38,720 --> 00:28:41,320 Speaker 1: know this one guy who was an engineer but then 553 00:28:41,320 --> 00:28:45,680 Speaker 1: he turned into a cartoonist. It sounds crazy, but you 554 00:28:45,680 --> 00:28:49,240 Speaker 1: can change careers. I heard he's now running a taco Chuck. 555 00:28:49,280 --> 00:28:53,240 Speaker 1: Isn't that true? Unfortunately it doesn't have a happy ending. 556 00:28:54,000 --> 00:28:56,400 Speaker 1: It's actually worse. He's doing a podcast. But the other 557 00:28:56,440 --> 00:28:58,440 Speaker 1: side to This is that you don't need to be 558 00:28:58,560 --> 00:29:02,120 Speaker 1: an official physicist with a hat p to ask interesting 559 00:29:02,200 --> 00:29:04,320 Speaker 1: questions about the universe and to think about it and 560 00:29:04,440 --> 00:29:06,840 Speaker 1: even to make progress. You know, there are lots of 561 00:29:06,840 --> 00:29:09,040 Speaker 1: people out there who have figured this stuff out on 562 00:29:09,080 --> 00:29:12,480 Speaker 1: their own, and physics is not owned by physics professors. 563 00:29:12,520 --> 00:29:15,840 Speaker 1: It belongs to everybody. Wondering and curiosity about the universe 564 00:29:16,040 --> 00:29:18,680 Speaker 1: belongs to everybody. So even if you aren't in a 565 00:29:18,760 --> 00:29:21,040 Speaker 1: situation in your life where you can't go back to 566 00:29:21,080 --> 00:29:24,240 Speaker 1: grad school in physics, you can still enjoy wondering about 567 00:29:24,240 --> 00:29:26,960 Speaker 1: the universe and learning about physics. Al Right, we have 568 00:29:27,000 --> 00:29:30,000 Speaker 1: a couple of more questions here from our most commonly 569 00:29:30,040 --> 00:29:32,960 Speaker 1: Asked Questions pile, and we'll get into them. They're about 570 00:29:33,000 --> 00:29:37,080 Speaker 1: black holes and gravitational waves. But first let's take another 571 00:29:37,200 --> 00:29:52,080 Speaker 1: quick break. All right, Daniel, we are going down our 572 00:29:52,120 --> 00:29:56,360 Speaker 1: list of most commonly asked questions to the podcast, and 573 00:29:56,400 --> 00:29:59,600 Speaker 1: our next question has to do with black holes. Question 574 00:29:59,680 --> 00:30:03,560 Speaker 1: goes do black holes move? And does this moving black 575 00:30:03,600 --> 00:30:08,600 Speaker 1: hole leave any trail quote unquote trail a stretched space? 576 00:30:08,920 --> 00:30:10,800 Speaker 1: And this is a question from a six year old 577 00:30:10,840 --> 00:30:13,200 Speaker 1: in particular. That's right, are you saying that a lot 578 00:30:13,240 --> 00:30:15,880 Speaker 1: of six year olds asked this question, or does this 579 00:30:15,960 --> 00:30:19,560 Speaker 1: six year old ask one of our most common questions. Yeah, 580 00:30:19,600 --> 00:30:22,240 Speaker 1: this six year old put his finger on a question 581 00:30:22,280 --> 00:30:24,320 Speaker 1: that we get a lot, which is, you know our 582 00:30:24,440 --> 00:30:27,240 Speaker 1: black holes sitting around or are they moving? And did 583 00:30:27,240 --> 00:30:29,880 Speaker 1: they leave with some sort of like wake in space 584 00:30:30,000 --> 00:30:32,280 Speaker 1: as they move the way like a boat leaves awake 585 00:30:32,400 --> 00:30:35,200 Speaker 1: in the lake. But I love that this question came 586 00:30:35,240 --> 00:30:38,040 Speaker 1: from a six year old thinking about black hole. So 587 00:30:38,280 --> 00:30:41,959 Speaker 1: congrats to is Sean and to his parents for encouraging 588 00:30:42,320 --> 00:30:45,080 Speaker 1: wonder and curiosity about the universe. Yes, so I guess 589 00:30:45,080 --> 00:30:47,640 Speaker 1: the question is, first of all, can black holes move 590 00:30:48,000 --> 00:30:51,400 Speaker 1: or are they so massive and monumental that they're basically 591 00:30:51,400 --> 00:30:54,080 Speaker 1: static in space? It's a great question, and we have 592 00:30:54,120 --> 00:30:57,120 Speaker 1: to remember, first of all that motion and position is 593 00:30:57,200 --> 00:31:01,040 Speaker 1: always relative, right, so there's no like absolute motion. You 594 00:31:01,080 --> 00:31:04,200 Speaker 1: can't ask is a black hole moving without saying what 595 00:31:04,320 --> 00:31:07,040 Speaker 1: is it moving relative to? The other side of that 596 00:31:07,160 --> 00:31:09,400 Speaker 1: is that black holes follow the same rules as everything else, 597 00:31:09,640 --> 00:31:13,200 Speaker 1: Stars and planets and galaxies, right, They all can move 598 00:31:13,280 --> 00:31:16,360 Speaker 1: through space or relative to each other, just like black holes. 599 00:31:16,600 --> 00:31:20,080 Speaker 1: And sometimes you'll see two black holes that are bound 600 00:31:20,080 --> 00:31:22,960 Speaker 1: to each other and orbiting each other. So yes, they 601 00:31:22,960 --> 00:31:26,240 Speaker 1: definitely can move through space just like everything else. Yeah, 602 00:31:26,240 --> 00:31:28,680 Speaker 1: and they can. I mean they basically add like any 603 00:31:28,720 --> 00:31:33,560 Speaker 1: other object in space to the things around them, right, Like, 604 00:31:33,640 --> 00:31:36,600 Speaker 1: you can have a black hole orbiting our solar system 605 00:31:36,640 --> 00:31:39,960 Speaker 1: for example. Yeah, you can't tell the difference gravitationally between 606 00:31:39,960 --> 00:31:42,840 Speaker 1: a black hole and another object of the same mass. 607 00:31:43,160 --> 00:31:44,960 Speaker 1: If you're at the same distance between those two, you 608 00:31:45,000 --> 00:31:47,959 Speaker 1: just can't tell the difference. They have the same gravitational effect. 609 00:31:48,280 --> 00:31:50,480 Speaker 1: So yeah, we could orbit a black hole the way 610 00:31:50,480 --> 00:31:52,840 Speaker 1: we orbit the Sun. We could have a tiny black 611 00:31:52,920 --> 00:31:55,440 Speaker 1: hole as part of our solar system that we wouldn't 612 00:31:55,480 --> 00:31:57,480 Speaker 1: even have noticed. In fact, there are those folks that 613 00:31:57,520 --> 00:32:01,160 Speaker 1: wonder about Planet nine whether it's a primordial hole that's 614 00:32:01,320 --> 00:32:04,160 Speaker 1: somehow stuck out there in the depth of our solar system. 615 00:32:04,200 --> 00:32:06,840 Speaker 1: So black holes can move through space, and you know, 616 00:32:07,000 --> 00:32:09,520 Speaker 1: there's even the possibility of black hole could move through 617 00:32:09,560 --> 00:32:12,640 Speaker 1: space and come disrupt our solar system. We did a 618 00:32:12,640 --> 00:32:15,120 Speaker 1: whole podcast episode about that. So yeah, they're not like 619 00:32:15,520 --> 00:32:19,000 Speaker 1: nailed in place there. They can move just like everything right. Yeah. 620 00:32:19,000 --> 00:32:20,960 Speaker 1: I wonder if what trips people up is that people 621 00:32:20,960 --> 00:32:23,880 Speaker 1: often talk about black holes or should I say, space 622 00:32:23,920 --> 00:32:28,960 Speaker 1: traps as being kind of these like holes punctured in 623 00:32:29,160 --> 00:32:33,080 Speaker 1: spacetime itself, or like these bubbles of space time. And 624 00:32:33,120 --> 00:32:35,600 Speaker 1: so maybe it's hard to think about it moving around 625 00:32:35,720 --> 00:32:37,880 Speaker 1: because it's I mean, when you punch a hole through 626 00:32:37,880 --> 00:32:39,640 Speaker 1: a piece of paper, it doesn't you can't move it. 627 00:32:40,400 --> 00:32:43,200 Speaker 1: That's a good point, but remember that's true for everything. 628 00:32:43,280 --> 00:32:45,800 Speaker 1: All kinds of matter change the shape of space, they 629 00:32:45,880 --> 00:32:50,160 Speaker 1: change the curvature they bend space, and where that is 630 00:32:50,280 --> 00:32:53,200 Speaker 1: just depends on your frame of reference, and whether it's 631 00:32:53,240 --> 00:32:56,520 Speaker 1: moving depends on whether you're moving. So if you can 632 00:32:56,560 --> 00:32:58,680 Speaker 1: move past a black hole, then a black hole can 633 00:32:58,720 --> 00:33:02,160 Speaker 1: move past you. There's no like absolute frame in which 634 00:33:02,200 --> 00:33:04,880 Speaker 1: these black holes are anchored. All right, Well, I guess 635 00:33:04,880 --> 00:33:08,160 Speaker 1: then the answer is yes, they can move. Space traps 636 00:33:08,720 --> 00:33:10,880 Speaker 1: can move, And so if you're out there in space, 637 00:33:11,240 --> 00:33:14,720 Speaker 1: watch out like you should look both ways before crossing 638 00:33:14,760 --> 00:33:17,240 Speaker 1: the Solar System lane. That's right. And the other part 639 00:33:17,240 --> 00:33:19,560 Speaker 1: of his question was whether or not they like leave 640 00:33:19,640 --> 00:33:22,720 Speaker 1: any trail behind them, and he like wake through space. 641 00:33:23,160 --> 00:33:25,960 Speaker 1: And we said earlier that the location of a black 642 00:33:25,960 --> 00:33:29,680 Speaker 1: hole and its velocity depends just on its frame of reference, 643 00:33:29,720 --> 00:33:32,080 Speaker 1: Like are you moving with respect to it. If so, 644 00:33:32,120 --> 00:33:35,640 Speaker 1: then it has velocity. But if a black hole is accelerating, 645 00:33:35,640 --> 00:33:39,440 Speaker 1: if it's changing its velocity, then it absolutely will leave 646 00:33:39,480 --> 00:33:42,080 Speaker 1: a wake through space the way a boat will when 647 00:33:42,120 --> 00:33:44,640 Speaker 1: it moves through a lake, and those weeks are called 648 00:33:44,680 --> 00:33:48,280 Speaker 1: gravitational waves. They will make these ripples in space. It's 649 00:33:48,320 --> 00:33:51,480 Speaker 1: like the change in velocity of something that is what 650 00:33:51,680 --> 00:33:56,200 Speaker 1: generates a gravitational wave. Yeah, exactly, because these frames of 651 00:33:56,240 --> 00:33:59,200 Speaker 1: reference are called inertial frames of reference, and you can't 652 00:33:59,200 --> 00:34:01,400 Speaker 1: tell the difference mean any of them as long as 653 00:34:01,440 --> 00:34:03,760 Speaker 1: they have no relative acceleration. But as soon as something 654 00:34:03,800 --> 00:34:07,480 Speaker 1: has an acceleration is changing its velocity, then it leaves 655 00:34:07,680 --> 00:34:11,320 Speaker 1: a signal through space. And those signals are these gravitational waves. 656 00:34:11,320 --> 00:34:15,080 Speaker 1: And that's what we've detected. In those underground detectors where 657 00:34:15,080 --> 00:34:17,600 Speaker 1: they have the long laser beams to measure the stretching 658 00:34:17,800 --> 00:34:20,760 Speaker 1: of space itself, they see two black holes, for example, 659 00:34:20,840 --> 00:34:23,920 Speaker 1: orbiting each other and leaving all these ripples in space, 660 00:34:24,440 --> 00:34:27,880 Speaker 1: which leads us to our next question. Speaking of gravitational waves, 661 00:34:27,960 --> 00:34:32,440 Speaker 1: another common question we get is our gravitational waves the 662 00:34:32,560 --> 00:34:36,680 Speaker 1: same as a graviton, meaning is a graviton a gravitational 663 00:34:36,719 --> 00:34:40,600 Speaker 1: wave or Can a gravitational wave be a graviton or 664 00:34:40,760 --> 00:34:43,360 Speaker 1: can just have a wave without a graviton. It's a 665 00:34:43,400 --> 00:34:46,120 Speaker 1: great question, and it's very natural because people think about 666 00:34:46,120 --> 00:34:49,440 Speaker 1: like electromagnetic waves, you know, they think about light, and 667 00:34:49,440 --> 00:34:51,439 Speaker 1: they know that light is made out of photons, these 668 00:34:51,480 --> 00:34:55,600 Speaker 1: little quantized units of electromagnetic radiation, and so it's very 669 00:34:55,680 --> 00:34:58,200 Speaker 1: natural to think about well, for gravity, if you have 670 00:34:58,239 --> 00:35:00,920 Speaker 1: gravitational waves, you know, is at the same thing as 671 00:35:00,920 --> 00:35:04,200 Speaker 1: a graviton, this whole particle wave duality. And the answer 672 00:35:04,320 --> 00:35:07,320 Speaker 1: is no. And the reason basically is that gravitational waves 673 00:35:07,320 --> 00:35:11,560 Speaker 1: are really really big. They're huge effects in gravity, and 674 00:35:11,640 --> 00:35:15,080 Speaker 1: gravitons if they exist, we expect them to be really 675 00:35:15,080 --> 00:35:19,080 Speaker 1: really really small. So a gravitational wave might be made 676 00:35:19,080 --> 00:35:22,879 Speaker 1: out of like zillions and zillions of gravitons the way, 677 00:35:22,920 --> 00:35:25,560 Speaker 1: for example, like a beam of light is made out 678 00:35:25,560 --> 00:35:28,200 Speaker 1: of lots and lots of photons, So they're not the 679 00:35:28,239 --> 00:35:31,640 Speaker 1: same thing. There are different scales and also gravitational waves, 680 00:35:31,680 --> 00:35:35,080 Speaker 1: and we know they exist. Gravitons still totally theoretic, right, 681 00:35:35,320 --> 00:35:37,200 Speaker 1: we don't know if they're actually real because we don't 682 00:35:37,200 --> 00:35:40,080 Speaker 1: know if gravity is quantum, that's right, The only theory 683 00:35:40,120 --> 00:35:43,080 Speaker 1: we have of gravity is this classical theory that says 684 00:35:43,320 --> 00:35:46,280 Speaker 1: that gravity is smooth and continuous. It's not like chopped 685 00:35:46,360 --> 00:35:50,000 Speaker 1: up into little units like everything else is. Like electromagnetic 686 00:35:50,000 --> 00:35:52,840 Speaker 1: waves are made out of little units we call photons. 687 00:35:52,840 --> 00:35:55,200 Speaker 1: You can't have an arbitrarily small size of them. They 688 00:35:55,239 --> 00:35:58,480 Speaker 1: come in discrete bits. And we don't know that about gravity. 689 00:35:58,520 --> 00:36:01,360 Speaker 1: We think probably it is because everything else is, but 690 00:36:01,400 --> 00:36:03,520 Speaker 1: we don't actually know that. We don't have a theory 691 00:36:03,600 --> 00:36:06,799 Speaker 1: for it. So the graviton is the particle you would 692 00:36:06,840 --> 00:36:09,279 Speaker 1: invent if you did have a theory of gravity. But 693 00:36:09,360 --> 00:36:12,600 Speaker 1: we know the gravitational waves are real. So those things 694 00:36:12,640 --> 00:36:14,839 Speaker 1: are out there, we've seen them. We don't know if 695 00:36:14,840 --> 00:36:17,319 Speaker 1: they're made out of tiny little gravitons. Right, it's kind 696 00:36:17,320 --> 00:36:19,640 Speaker 1: of like a water I guess, you know, like a 697 00:36:19,640 --> 00:36:22,360 Speaker 1: a wave in water. That's not the same as a 698 00:36:22,360 --> 00:36:25,960 Speaker 1: molecule of water. Yeah, we'd love to discover those water molecules. 699 00:36:26,000 --> 00:36:28,759 Speaker 1: We'd love to figure out if gravity is quantum and 700 00:36:28,800 --> 00:36:30,919 Speaker 1: if it's made out of gravitons. But we haven't seen 701 00:36:30,920 --> 00:36:34,040 Speaker 1: those yet. And it's really hard because even the gravitational 702 00:36:34,120 --> 00:36:37,000 Speaker 1: waves are hard to spot because gravity is really, really 703 00:36:37,040 --> 00:36:40,120 Speaker 1: weak compared to all the other forces. It's like billions 704 00:36:40,120 --> 00:36:43,279 Speaker 1: and trillions times weaker, which means it's very hard to 705 00:36:43,280 --> 00:36:46,040 Speaker 1: see it effects. And so to see a graviton would 706 00:36:46,040 --> 00:36:48,840 Speaker 1: be to see a even tinier little bit of gravity. 707 00:36:48,840 --> 00:36:51,600 Speaker 1: We're just not nearly sensitive enough, all right, So I 708 00:36:51,600 --> 00:36:54,560 Speaker 1: guess the answer is a gravitational wave is a gravity nut, 709 00:36:55,160 --> 00:36:58,920 Speaker 1: not necessarily graviton. All right. Then I think we have 710 00:36:59,160 --> 00:37:02,640 Speaker 1: time for one more of our most commonly asked question pile, 711 00:37:02,880 --> 00:37:05,640 Speaker 1: and I'm going to pick this one here, which says, 712 00:37:06,280 --> 00:37:10,360 Speaker 1: if he equals mc squared and a photon is massless, 713 00:37:10,560 --> 00:37:13,560 Speaker 1: then how does a photon have any energy? How can 714 00:37:13,600 --> 00:37:16,800 Speaker 1: a photon have energy if it's massless? Yeah, this is 715 00:37:16,800 --> 00:37:18,960 Speaker 1: a great question, and I love that people are doing 716 00:37:19,000 --> 00:37:21,239 Speaker 1: this thinking they're like, I have this one idea and 717 00:37:21,400 --> 00:37:23,799 Speaker 1: this other idea. Can I bring them together? Does this 718 00:37:23,880 --> 00:37:26,920 Speaker 1: make sense? And that's physics, right, that's doing physics. It's 719 00:37:26,960 --> 00:37:30,080 Speaker 1: saying I have this rule, where does it apply? Let 720 00:37:30,120 --> 00:37:32,719 Speaker 1: me check make sure that it applies everywhere I understand it. 721 00:37:33,120 --> 00:37:35,719 Speaker 1: And so it's great. Kudos to everybody who thinks about 722 00:37:35,760 --> 00:37:38,000 Speaker 1: this and to ask this question. This one came from 723 00:37:38,080 --> 00:37:41,600 Speaker 1: James Chad. And so the answer is that the formula 724 00:37:41,640 --> 00:37:43,920 Speaker 1: equals m C squared. It is not false, it's true, 725 00:37:44,000 --> 00:37:47,280 Speaker 1: but it's not the most general formula. It's only talking 726 00:37:47,320 --> 00:37:50,200 Speaker 1: about the energy that you get from mass. And there 727 00:37:50,200 --> 00:37:52,239 Speaker 1: are lots of forms of energy, right, there's energy and 728 00:37:52,280 --> 00:37:56,719 Speaker 1: mass is also energy of motion. Right, there's energy of rotation, 729 00:37:57,040 --> 00:38:01,360 Speaker 1: the energy of vibration. These are are other forms of energy, right, 730 00:38:01,480 --> 00:38:04,000 Speaker 1: But don't they all get lumped at the same energy 731 00:38:04,160 --> 00:38:07,160 Speaker 1: at the end, right, Like if I have a slow 732 00:38:07,200 --> 00:38:10,520 Speaker 1: moving particle and a fast moving particle, then the fast 733 00:38:10,520 --> 00:38:14,920 Speaker 1: moving particle has more energy and can transform into you know, 734 00:38:15,239 --> 00:38:18,120 Speaker 1: heavier particles. Yes, that's true. And so the most general 735 00:38:18,160 --> 00:38:22,319 Speaker 1: expression for energy is not E equals mc squared. That's 736 00:38:22,360 --> 00:38:24,600 Speaker 1: the expression you would use for a particle that's essentially 737 00:38:24,600 --> 00:38:27,879 Speaker 1: not moving. There's a more general expression that says E 738 00:38:27,880 --> 00:38:31,719 Speaker 1: equals mc squared plus momentum times the speed of light 739 00:38:31,880 --> 00:38:36,000 Speaker 1: P time c. So there's another term there. And so 740 00:38:36,120 --> 00:38:38,839 Speaker 1: for a photon, mass is zero. It doesn't have any 741 00:38:38,840 --> 00:38:41,279 Speaker 1: of this rest mass that the other particles have, but 742 00:38:41,400 --> 00:38:45,880 Speaker 1: it does have momentum. Photons are essentially are pure momentum. 743 00:38:46,160 --> 00:38:49,760 Speaker 1: There the wiggle of the electromagnetic field. There are pure motion, 744 00:38:50,000 --> 00:38:52,680 Speaker 1: there's no mass to them. But wait, it doesn't momentum 745 00:38:52,719 --> 00:38:55,920 Speaker 1: imply mass like it. Remember an engineering, when you study momentum, 746 00:38:55,960 --> 00:38:59,719 Speaker 1: it's M times V, so mass times velocity. That's the 747 00:38:59,800 --> 00:39:04,640 Speaker 1: non relativistic expression for momentum M times v. In relativity 748 00:39:04,760 --> 00:39:07,200 Speaker 1: we have a more general expression for momentum, and we 749 00:39:07,200 --> 00:39:09,360 Speaker 1: can dive deeper into that rabbit hole. But now you 750 00:39:09,360 --> 00:39:12,799 Speaker 1: do not have to have mass to have momentum, and 751 00:39:12,840 --> 00:39:15,200 Speaker 1: photons we know have momentum. We talked about for example, 752 00:39:15,239 --> 00:39:19,520 Speaker 1: solar sales. Photons themselves from the Sun can push on something. 753 00:39:19,680 --> 00:39:22,520 Speaker 1: When they bounce off of it, they transfer their momentum 754 00:39:22,560 --> 00:39:25,759 Speaker 1: to the solar sale. So we know physically empirically the 755 00:39:25,800 --> 00:39:30,720 Speaker 1: photons definitely do have momentum and they are essentially pure momentum. 756 00:39:30,800 --> 00:39:33,440 Speaker 1: And so equals mc squared is the best known formula, 757 00:39:33,640 --> 00:39:36,160 Speaker 1: but it's not the most general case, and imparticle physics, 758 00:39:36,160 --> 00:39:40,000 Speaker 1: we use equals mc squared plus pc and so for 759 00:39:40,040 --> 00:39:42,719 Speaker 1: the photon m equal zero and the energy is just 760 00:39:43,000 --> 00:39:45,920 Speaker 1: momentum times the speed of light p time c. So 761 00:39:45,960 --> 00:39:49,520 Speaker 1: it does have energy. Photons have energy, it just doesn't 762 00:39:49,560 --> 00:39:51,919 Speaker 1: come from it having mass. It just comes from its motion. 763 00:39:52,000 --> 00:39:53,920 Speaker 1: That's right. There are other ways to have energy, and 764 00:39:53,920 --> 00:39:56,440 Speaker 1: that's what photons do, and they're weird because they have 765 00:39:56,560 --> 00:39:59,880 Speaker 1: exactly zero mass. And it's more general. Formula applies to 766 00:39:59,920 --> 00:40:03,640 Speaker 1: me in you too, Like my energy is both how 767 00:40:03,719 --> 00:40:06,719 Speaker 1: much I wait, but also how much a movie? Yeah, exactly, 768 00:40:07,000 --> 00:40:08,960 Speaker 1: you have more energy if you're in motion then when 769 00:40:08,960 --> 00:40:13,080 Speaker 1: you're sitting on your couch. Who all right, Well, those 770 00:40:13,120 --> 00:40:16,520 Speaker 1: are some of our most common questions, Daniel. What do 771 00:40:16,520 --> 00:40:19,040 Speaker 1: you sort of make of all these questions? I make 772 00:40:19,080 --> 00:40:21,600 Speaker 1: that we have smart listeners, then that we have people 773 00:40:21,600 --> 00:40:24,440 Speaker 1: out there that are intrigued by the way the universe works, 774 00:40:24,800 --> 00:40:27,560 Speaker 1: and that this stuff is complicated, and that if you 775 00:40:27,600 --> 00:40:30,120 Speaker 1: try to download it into your brain and play around 776 00:40:30,160 --> 00:40:32,560 Speaker 1: with it, you'll find little rough edges that you don't 777 00:40:32,640 --> 00:40:35,640 Speaker 1: quite understand, or little bits that don't quite click together, 778 00:40:36,160 --> 00:40:38,160 Speaker 1: and that that's not unusual, and that there are a 779 00:40:38,160 --> 00:40:40,560 Speaker 1: lot of other people out there wondering about those same 780 00:40:40,600 --> 00:40:43,799 Speaker 1: tricky bits. So I hope that these answers have helped 781 00:40:43,840 --> 00:40:46,840 Speaker 1: a lot of people collect those pieces together, and if not, 782 00:40:47,000 --> 00:40:48,840 Speaker 1: feel free to write into us. We would love to 783 00:40:48,880 --> 00:40:52,239 Speaker 1: help you resolve little questions you have about your understanding 784 00:40:52,360 --> 00:40:54,759 Speaker 1: about the universe. Yeah, and in some cases I feel 785 00:40:54,800 --> 00:40:57,600 Speaker 1: like your answer was we don't know, which means that 786 00:40:57,760 --> 00:41:01,200 Speaker 1: these are questions that physicists are also asking themselves at 787 00:41:01,200 --> 00:41:03,920 Speaker 1: the forefront of science. Yeah. Basically, at the end of 788 00:41:04,000 --> 00:41:06,879 Speaker 1: every question, you could add and what does that even mean? 789 00:41:07,680 --> 00:41:11,120 Speaker 1: Exclamation point question mark? And we'll add a few more 790 00:41:11,200 --> 00:41:12,920 Speaker 1: question marks there at the end. Two. That should be 791 00:41:12,960 --> 00:41:17,560 Speaker 1: the alt title for our podcast exclamation point question mark 792 00:41:18,160 --> 00:41:21,239 Speaker 1: or maybe our next book, Daniel, what does that even mean? 793 00:41:21,719 --> 00:41:25,120 Speaker 1: Exclamation point question mark? To which the answer is the 794 00:41:25,160 --> 00:41:28,600 Speaker 1: title of our first book. We have no idea. It's 795 00:41:28,640 --> 00:41:31,759 Speaker 1: a recursive book. Really, that's right. Book three. Let's just 796 00:41:31,800 --> 00:41:34,440 Speaker 1: go get tacos. Go go back and read our first 797 00:41:34,440 --> 00:41:38,799 Speaker 1: book while eating some tacos and increasing your volume. That's 798 00:41:38,920 --> 00:41:41,760 Speaker 1: all right. Well, we hope you enjoyed that and maybe 799 00:41:41,760 --> 00:41:43,960 Speaker 1: connected a little bit more with people out there, because 800 00:41:44,000 --> 00:41:45,920 Speaker 1: we all have a lot of the same questions about 801 00:41:45,920 --> 00:41:48,160 Speaker 1: the universe and don't be shy about writing to us, 802 00:41:48,200 --> 00:41:51,480 Speaker 1: were engaging with us on Twitter at Daniel and Jorge 803 00:41:51,760 --> 00:41:54,720 Speaker 1: or sending us email to questions at Daniel and Jorge 804 00:41:54,760 --> 00:41:57,720 Speaker 1: dot com. We love your listener questions and we answer 805 00:41:57,840 --> 00:41:59,600 Speaker 1: all of our email. Yeah, and don't be shy but 806 00:41:59,760 --> 00:42:03,480 Speaker 1: ask questions and pursuing knowledge and even maybe getting a 807 00:42:03,600 --> 00:42:08,000 Speaker 1: physics degree late in life. Thanks for joining us, see 808 00:42:08,000 --> 00:42:18,200 Speaker 1: you next time. Thanks for listening, and remember that Daniel 809 00:42:18,239 --> 00:42:20,759 Speaker 1: and Jorge explained The Universe is a production of I 810 00:42:21,000 --> 00:42:24,399 Speaker 1: Heart Radio. For more podcast from my heart Radio, visit 811 00:42:24,440 --> 00:42:27,960 Speaker 1: the I Heart Radio Apple Apple Podcasts, or wherever you 812 00:42:28,040 --> 00:42:29,560 Speaker 1: listen to your favorite shows.