1 00:00:08,520 --> 00:00:10,480 Speaker 1: Hey, Daniel, I heard you grew up in Los Alamos, 2 00:00:10,560 --> 00:00:14,080 Speaker 1: New Mexico, home of the Manhattan Project. Oh yeah, that's true. 3 00:00:14,200 --> 00:00:17,400 Speaker 1: But before you ask, our high school mascot was not 4 00:00:17,640 --> 00:00:22,360 Speaker 1: the atomic bomb. It wasn't a Tommy or hydrogen. That 5 00:00:22,360 --> 00:00:24,480 Speaker 1: would be in bad taste. No, but we did bomb 6 00:00:24,480 --> 00:00:28,240 Speaker 1: at all of our home football games. Oh that's a 7 00:00:28,320 --> 00:00:31,000 Speaker 1: radioactive topic. But I do have a question for you. 8 00:00:31,120 --> 00:00:34,360 Speaker 1: All right, The people in Los Alamos glow in the dark, 9 00:00:34,479 --> 00:00:36,960 Speaker 1: you know, because of all that radiation. No, though that 10 00:00:37,000 --> 00:00:39,159 Speaker 1: would be useful at night. But I do have an 11 00:00:39,159 --> 00:00:41,640 Speaker 1: extra eyeball that I try to keep closed in the public. 12 00:00:43,040 --> 00:00:45,440 Speaker 1: Does that give you extra death perceptive or lets you 13 00:00:45,479 --> 00:00:47,960 Speaker 1: keep an eye on your kids more easily? Lets me 14 00:00:48,000 --> 00:00:50,360 Speaker 1: see the world in three D? Cool? But I guess 15 00:00:50,360 --> 00:01:09,759 Speaker 1: that makes getting glasses kind of paine. Hi'm more handmade 16 00:01:09,760 --> 00:01:12,640 Speaker 1: cartoonist and the creator of PhD comments. Hi, I'm Daniel. 17 00:01:12,680 --> 00:01:15,679 Speaker 1: I'm a particle physicist, and I don't really glow in 18 00:01:15,720 --> 00:01:18,400 Speaker 1: the dark. Really what spectrum? Though? Don't you glow in 19 00:01:18,440 --> 00:01:21,280 Speaker 1: the darkness certain spectrums of light? No, I absolutely do. 20 00:01:21,319 --> 00:01:23,280 Speaker 1: I should have said I'm a particle physicist and I 21 00:01:23,360 --> 00:01:25,440 Speaker 1: do actually glow in the dark, just the way I 22 00:01:25,520 --> 00:01:28,040 Speaker 1: do and you do and everybody does. We all glow 23 00:01:28,160 --> 00:01:32,080 Speaker 1: in the infrared. Yes, if we all had I guess 24 00:01:32,080 --> 00:01:34,800 Speaker 1: special night goggles, we would all see each other glow 25 00:01:34,800 --> 00:01:37,080 Speaker 1: in at night. Yeah. Or if we had evolved eyeballs 26 00:01:37,120 --> 00:01:39,880 Speaker 1: that could see in the infrared. Oh, that would be cool. Yeah, 27 00:01:40,040 --> 00:01:41,600 Speaker 1: we would be able to tell when people are sick 28 00:01:41,600 --> 00:01:44,080 Speaker 1: and everything, right, kind of, they have a fever, that's right, 29 00:01:44,120 --> 00:01:46,240 Speaker 1: we could spot the virus with our naked eyes. Are 30 00:01:46,240 --> 00:01:48,800 Speaker 1: you saying everybody has an aura about them kind of 31 00:01:48,920 --> 00:01:52,400 Speaker 1: in some frequencies of light. The physics of aura's exactly. 32 00:01:52,560 --> 00:01:55,280 Speaker 1: Welcome to our podcast. Daniel and Jorge explain the university 33 00:01:55,360 --> 00:01:57,600 Speaker 1: production of I Heart Radio, in which we'd like to 34 00:01:57,640 --> 00:02:00,160 Speaker 1: talk about the physics of the crazy, the insane, in 35 00:02:00,160 --> 00:02:03,240 Speaker 1: the quantum mechanical, the black holes, the neutron stars, the 36 00:02:03,280 --> 00:02:06,040 Speaker 1: centers of galaxies. But we also like to talk about 37 00:02:06,120 --> 00:02:09,280 Speaker 1: the physics of the every day. Doing physics about the 38 00:02:09,320 --> 00:02:13,280 Speaker 1: universe means understanding everything we see around us, Understanding the 39 00:02:13,360 --> 00:02:17,680 Speaker 1: microscopic mechanisms that determine everything that happens inside our bodies 40 00:02:17,720 --> 00:02:20,880 Speaker 1: and outside our bodies. Yeah, because physics is all around us. 41 00:02:20,919 --> 00:02:23,200 Speaker 1: It's not just out there in space and the farthest 42 00:02:23,200 --> 00:02:26,600 Speaker 1: reaches of the cosmos and black holes and stars and planets. 43 00:02:26,600 --> 00:02:29,600 Speaker 1: It's also right here all around us, and the things 44 00:02:29,639 --> 00:02:31,320 Speaker 1: that you touch every day, and the things that you 45 00:02:31,520 --> 00:02:34,240 Speaker 1: play with and activate every day, and like you said, 46 00:02:34,240 --> 00:02:36,679 Speaker 1: in our own bodies as well. Yeah, I think it's 47 00:02:36,680 --> 00:02:39,920 Speaker 1: sort of amazing and beautiful. How physics. Let's just like 48 00:02:40,040 --> 00:02:43,360 Speaker 1: peel back a layer of reality and see the tiny 49 00:02:43,440 --> 00:02:46,840 Speaker 1: little microscopic things that are causing that behavior. You know, 50 00:02:46,880 --> 00:02:49,800 Speaker 1: the reasons that metals are shiny, or that liquids flow, 51 00:02:49,960 --> 00:02:52,600 Speaker 1: or that gases burn. All of its physics at the 52 00:02:52,639 --> 00:02:55,640 Speaker 1: lowest level, the rules that govern those tiny little particles 53 00:02:55,880 --> 00:02:59,560 Speaker 1: eventually bubble up and determine basically everything about the universe. 54 00:02:59,800 --> 00:03:02,080 Speaker 1: And it's cool to go in both directions to see 55 00:03:02,160 --> 00:03:04,760 Speaker 1: something you don't understand and take it apart into its 56 00:03:04,800 --> 00:03:07,480 Speaker 1: microscopic little components, and to go to the other direction 57 00:03:07,560 --> 00:03:10,160 Speaker 1: and to understand from the bottom up how the rules 58 00:03:10,160 --> 00:03:13,200 Speaker 1: of the universe determine our experience. Did you say physics 59 00:03:13,320 --> 00:03:16,120 Speaker 1: is at the lowest levels or at the glowest levels? 60 00:03:17,800 --> 00:03:21,040 Speaker 1: Was that a little unintentional slip there, that's right? Halloween 61 00:03:21,120 --> 00:03:23,000 Speaker 1: is coming, and so I have glow in the dark 62 00:03:23,080 --> 00:03:25,800 Speaker 1: things in my mind. Your kids have those, like glowing 63 00:03:25,840 --> 00:03:28,240 Speaker 1: the dark stars up in their ceilings. They do, but 64 00:03:28,320 --> 00:03:31,040 Speaker 1: they're getting fainter and fainter every year, maybe because of 65 00:03:31,120 --> 00:03:35,640 Speaker 1: dark energy. Oh, interesting, I don't think that's the thing 66 00:03:35,760 --> 00:03:39,400 Speaker 1: is Oh? I see? Are you saying that the room 67 00:03:39,440 --> 00:03:42,680 Speaker 1: is getting bigger and bigger and so therefore the stars 68 00:03:42,720 --> 00:03:45,520 Speaker 1: are getting fainter and fainter. No, the universe is getting 69 00:03:45,560 --> 00:03:48,800 Speaker 1: darker and darker because galaxies are accelerating away from us 70 00:03:48,840 --> 00:03:51,720 Speaker 1: faster and faster every year, and so our actual night 71 00:03:51,760 --> 00:03:55,040 Speaker 1: sky is getting darker and darker. And my kids cheap 72 00:03:55,080 --> 00:03:57,520 Speaker 1: o glow in the dark stars are also fading, but 73 00:03:57,720 --> 00:04:02,080 Speaker 1: for a different reason. So they are acci dentally, scientifically accurate. Well, 74 00:04:02,080 --> 00:04:04,520 Speaker 1: that is something that is in our everyday lives, especially 75 00:04:04,600 --> 00:04:07,440 Speaker 1: around this time of Halloween. Glow in the dark things, 76 00:04:08,000 --> 00:04:10,600 Speaker 1: things that glow into dark that people make, little like 77 00:04:10,680 --> 00:04:13,080 Speaker 1: ghosts and decorations that glow in the dark. That's right. 78 00:04:13,120 --> 00:04:15,000 Speaker 1: And if you have physics on the brain and then 79 00:04:15,040 --> 00:04:17,480 Speaker 1: you look at that and you wonder, how does that happen? 80 00:04:17,600 --> 00:04:19,600 Speaker 1: And I got a lot of questions from listeners who 81 00:04:19,640 --> 00:04:22,520 Speaker 1: want to understand the very basics of how light works, 82 00:04:22,640 --> 00:04:25,240 Speaker 1: how photons bounce off of things and sometimes reflect and 83 00:04:25,279 --> 00:04:28,040 Speaker 1: sometimes absorb, and how you get mirrors, and why things 84 00:04:28,040 --> 00:04:30,640 Speaker 1: look like different colors. And this is a very basic 85 00:04:30,720 --> 00:04:32,840 Speaker 1: question I remember wondering about as a kid, you know, 86 00:04:32,920 --> 00:04:36,200 Speaker 1: like how light travels and why things are various colors 87 00:04:36,279 --> 00:04:38,800 Speaker 1: and how that all works. Yeah. I do remember in 88 00:04:38,880 --> 00:04:41,040 Speaker 1: the mid eighties, like getting my first glow in the 89 00:04:41,160 --> 00:04:43,640 Speaker 1: dark thing. I think it was a frisbee maybe or 90 00:04:43,760 --> 00:04:46,279 Speaker 1: something in a T shirt, and I just remember thinking like, Wow, 91 00:04:46,320 --> 00:04:49,160 Speaker 1: that's amazing, that's like magic. How does that work? That's right? 92 00:04:49,200 --> 00:04:52,839 Speaker 1: And the answer is always physics. Well, I have to say, 93 00:04:52,960 --> 00:04:55,040 Speaker 1: when I grew up, I stop wondering about it because 94 00:04:55,040 --> 00:04:58,280 Speaker 1: I just look at that and think, oh, that's just chemistry. 95 00:04:58,680 --> 00:05:01,200 Speaker 1: Just chemistry, right, all you chemists out there, you just 96 00:05:01,240 --> 00:05:06,400 Speaker 1: got like totally dissed ambating YouTube. No, it's the wonderful 97 00:05:06,480 --> 00:05:11,120 Speaker 1: world of chemistry, the magnificent questions answered by chemistry. No, 98 00:05:11,279 --> 00:05:13,280 Speaker 1: chemistry is too complicated for me. I can't think about 99 00:05:13,279 --> 00:05:16,200 Speaker 1: all those particles at the same time. I see you 100 00:05:16,320 --> 00:05:18,960 Speaker 1: like to drill down to the individual party. I have 101 00:05:19,240 --> 00:05:22,400 Speaker 1: utmost respect for chemists and biologists who can think about 102 00:05:22,400 --> 00:05:25,159 Speaker 1: such complex systems. I like to take things apart and 103 00:05:25,200 --> 00:05:28,560 Speaker 1: think about a single particle interacting with one other particle. Well, 104 00:05:28,600 --> 00:05:31,040 Speaker 1: that is a pretty interesting question. How did glow in 105 00:05:31,080 --> 00:05:33,640 Speaker 1: the dark? Things glow? And I wish we could we 106 00:05:33,640 --> 00:05:36,040 Speaker 1: could go back in time and tell my eighties kid 107 00:05:36,160 --> 00:05:38,479 Speaker 1: self about it. So it's on the podcast. We'll be 108 00:05:38,520 --> 00:05:47,120 Speaker 1: talking about why do things glow in the dark? And 109 00:05:47,160 --> 00:05:49,560 Speaker 1: I guess you mean, like certain things? Why do all 110 00:05:49,600 --> 00:05:51,080 Speaker 1: things glow in the dark? Or why do you like 111 00:05:51,120 --> 00:05:53,279 Speaker 1: glow in the dark? Things glow in the dark? Yeah, well, 112 00:05:53,320 --> 00:05:55,760 Speaker 1: some things glow in the visible, other things glow in 113 00:05:55,800 --> 00:05:58,680 Speaker 1: the invisible. And it turns out almost everything in the 114 00:05:58,760 --> 00:06:02,240 Speaker 1: universe glows in some way or another. And there's a 115 00:06:02,279 --> 00:06:05,240 Speaker 1: lot of really subtle physics going on about how things 116 00:06:05,240 --> 00:06:08,239 Speaker 1: absorbed light when they decide to give it off, what's 117 00:06:08,240 --> 00:06:10,800 Speaker 1: going on in between, and whether or not we could 118 00:06:10,839 --> 00:06:14,719 Speaker 1: use that to understand things like black holes. Mm. Interesting, 119 00:06:14,839 --> 00:06:16,600 Speaker 1: I guess all things glow in the dark, or at 120 00:06:16,680 --> 00:06:20,320 Speaker 1: least all things that have a temperature other than zero kelvin, right, 121 00:06:20,360 --> 00:06:23,880 Speaker 1: technically they glow in the dark. Almost almost all things 122 00:06:23,880 --> 00:06:27,480 Speaker 1: that have a temperature things interesting. But I guess what 123 00:06:27,520 --> 00:06:29,960 Speaker 1: we mean today is how do things that glow in 124 00:06:30,000 --> 00:06:33,039 Speaker 1: the visible light spectrum? Those things that glow without any 125 00:06:33,040 --> 00:06:35,800 Speaker 1: electricity or any kind of a battery source, How did 126 00:06:35,839 --> 00:06:39,000 Speaker 1: those glow in the dark? Exactly? What is the physics 127 00:06:39,000 --> 00:06:40,720 Speaker 1: of that? So it's usually we'll be were wondering how 128 00:06:40,720 --> 00:06:43,320 Speaker 1: many people out there have thought about this question looking 129 00:06:43,360 --> 00:06:46,440 Speaker 1: at their star stickies in their ceiling or a Halloween 130 00:06:46,480 --> 00:06:49,400 Speaker 1: decorations and wondered what makes something glow in the dark. 131 00:06:49,600 --> 00:06:51,279 Speaker 1: So Daniel went out there into the wilds of the 132 00:06:51,279 --> 00:06:55,040 Speaker 1: internet to ask people this question. So thanks everybody who volunteered. 133 00:06:55,120 --> 00:06:57,440 Speaker 1: And if you would like to participate and hear your 134 00:06:57,560 --> 00:06:59,599 Speaker 1: voice on the podcast and you think you have some 135 00:06:59,680 --> 00:07:02,200 Speaker 1: good is there is, please write to us two questions 136 00:07:02,240 --> 00:07:05,560 Speaker 1: at Daniel and Jorge dot com. Everybody is very welcome. 137 00:07:05,920 --> 00:07:08,479 Speaker 1: So think about it for a second. Did you owe 138 00:07:08,560 --> 00:07:11,560 Speaker 1: a glow worm when you were a kid, and ever 139 00:07:11,680 --> 00:07:15,080 Speaker 1: wonder how it works. Here's what people had to say. 140 00:07:15,240 --> 00:07:19,160 Speaker 1: I'm inclined to say temperature is what makes the things 141 00:07:19,200 --> 00:07:23,680 Speaker 1: glow in the dark, but in case of bioluminouscence in 142 00:07:24,000 --> 00:07:26,520 Speaker 1: like fireflies or something, it's probably something else. It might 143 00:07:26,560 --> 00:07:32,280 Speaker 1: be something involving some biological compound combined with electricity. I'm 144 00:07:32,280 --> 00:07:36,360 Speaker 1: not sure how that works, really, but I'd say temperature 145 00:07:36,440 --> 00:07:39,000 Speaker 1: is the usual suspect. The first thing that comes to 146 00:07:39,120 --> 00:07:43,400 Speaker 1: mind is bioluminouscence. I'm sorry if I'm saying that wrong. 147 00:07:43,720 --> 00:07:45,920 Speaker 1: I don't know how to pronounce that in English correctly. 148 00:07:46,640 --> 00:07:50,200 Speaker 1: But it's like some fish in the deep water, they 149 00:07:50,240 --> 00:07:53,400 Speaker 1: create kind of their own light. We also see that 150 00:07:53,520 --> 00:07:56,880 Speaker 1: sometimes with algae in the ocean, but I don't know 151 00:07:57,040 --> 00:08:02,000 Speaker 1: how that works. I'm guessing it's a mixture of chemicals. 152 00:08:02,400 --> 00:08:04,960 Speaker 1: I've never thought about that. I know that there are 153 00:08:05,520 --> 00:08:12,440 Speaker 1: certain chemical processes that can excite electrons in the correct way, 154 00:08:12,440 --> 00:08:17,400 Speaker 1: and there's also bioluminescence that some organisms have. I think 155 00:08:17,760 --> 00:08:20,320 Speaker 1: to glow in the dark, you have to be able 156 00:08:20,400 --> 00:08:25,960 Speaker 1: to generate your own form of energy and admit that 157 00:08:26,000 --> 00:08:28,760 Speaker 1: in some way. But I'm not sure of any other specifics. 158 00:08:29,840 --> 00:08:32,559 Speaker 1: Interesting a lot of answers here the point to biology. 159 00:08:32,840 --> 00:08:37,640 Speaker 1: They skip right over chemistry and went to bioluminescence. Man, 160 00:08:37,760 --> 00:08:41,200 Speaker 1: that's a double insult there. No, it's all part of 161 00:08:41,200 --> 00:08:43,920 Speaker 1: the same wonderful spectrum of science. But does make you 162 00:08:43,960 --> 00:08:46,000 Speaker 1: realize that there are lots of ways that things glow 163 00:08:46,040 --> 00:08:48,280 Speaker 1: in the dark. You know, they're like algae that glow 164 00:08:48,280 --> 00:08:50,600 Speaker 1: in the ocean and their fish. And then there's also 165 00:08:50,760 --> 00:08:52,679 Speaker 1: you know those watches that have like glow in the 166 00:08:52,800 --> 00:08:55,320 Speaker 1: dark hands, And I remember as a kid thinking that 167 00:08:55,360 --> 00:08:57,599 Speaker 1: those were amazing and wondering why they faded as the 168 00:08:57,679 --> 00:08:59,840 Speaker 1: night went on. It was sort of like they captured 169 00:09:00,200 --> 00:09:03,200 Speaker 1: sunlight and they were like slowly releasing it later, Like 170 00:09:03,200 --> 00:09:06,160 Speaker 1: how do you capture photons? It's like I always imagined, 171 00:09:06,200 --> 00:09:08,880 Speaker 1: like are their photons running around in circles inside those 172 00:09:08,880 --> 00:09:11,520 Speaker 1: little watch hands? And there's also those glow sticks, right, 173 00:09:11,559 --> 00:09:13,200 Speaker 1: I mean I don't go to a lot of raves, 174 00:09:13,320 --> 00:09:16,400 Speaker 1: but I've heard that they use sticks a lot in those, 175 00:09:16,559 --> 00:09:18,520 Speaker 1: and they're used a lot in like, you know, the 176 00:09:18,559 --> 00:09:21,520 Speaker 1: Halloween too, right, Yeah, absolutely, we always deck our kids 177 00:09:21,520 --> 00:09:23,400 Speaker 1: out with glowing stuff so they don't get run over. 178 00:09:23,520 --> 00:09:26,000 Speaker 1: So there's lots of ways that you can emit light. 179 00:09:26,160 --> 00:09:28,040 Speaker 1: You know, I think we should distinguish between things that 180 00:09:28,080 --> 00:09:31,400 Speaker 1: like just reflect light and things that actually give off 181 00:09:31,480 --> 00:09:34,280 Speaker 1: their own light, right because I guess, you know, like 182 00:09:34,320 --> 00:09:37,400 Speaker 1: the moon doesn't midlight by itself, we only see it 183 00:09:37,440 --> 00:09:41,000 Speaker 1: at night because it's reflecting light from the sun. That's right. 184 00:09:41,120 --> 00:09:44,439 Speaker 1: Most of the light that you see is actually reflected, right, 185 00:09:44,520 --> 00:09:46,120 Speaker 1: all the light from the sun. When you look at 186 00:09:46,120 --> 00:09:48,880 Speaker 1: the ground, you're looking at reflected light from the sun. 187 00:09:49,080 --> 00:09:51,520 Speaker 1: The ground is not like glowing in the visible light. 188 00:09:51,840 --> 00:09:53,880 Speaker 1: And if you turned off the sun, the ground would 189 00:09:53,880 --> 00:09:55,640 Speaker 1: be dark, right. And the same thing with the moon. 190 00:09:55,720 --> 00:09:57,880 Speaker 1: The moon has a dark side and a light side, 191 00:09:57,880 --> 00:09:59,760 Speaker 1: and you only see the light side because you were 192 00:09:59,800 --> 00:10:03,080 Speaker 1: see light reflected off the moon from the sun in 193 00:10:03,080 --> 00:10:06,280 Speaker 1: the visible light spectrum. Again, right in the visible light spectrum. Yeah, 194 00:10:06,360 --> 00:10:09,680 Speaker 1: so you know moonlight is actually just sunlight, right, that's 195 00:10:09,679 --> 00:10:12,160 Speaker 1: been reflected off of the moon. Which makes me wonder 196 00:10:12,160 --> 00:10:14,719 Speaker 1: about all those creatures that you know, like only can 197 00:10:14,800 --> 00:10:17,880 Speaker 1: live in the moonlight or whatever, like vampires. Wait, what 198 00:10:18,320 --> 00:10:21,719 Speaker 1: are creatures we can only live in the moonlight on 199 00:10:21,760 --> 00:10:25,439 Speaker 1: the moon or here on earth, nodological creatures. Don't vampires 200 00:10:25,520 --> 00:10:29,719 Speaker 1: turn to stone in sunlight or something? Oh boy, you're 201 00:10:29,720 --> 00:10:33,000 Speaker 1: really confusing me here today with chemistry and biology and 202 00:10:33,120 --> 00:10:37,400 Speaker 1: mythical creatures and visible light, we're doing the plasics of 203 00:10:37,480 --> 00:10:41,359 Speaker 1: vampires today from Daniel takes apart The science of vampires 204 00:10:41,640 --> 00:10:44,199 Speaker 1: and you know, the Sun itself is actually glowing, it's 205 00:10:44,280 --> 00:10:47,000 Speaker 1: actually emitting light. But the Earth and the Moon and 206 00:10:47,120 --> 00:10:49,480 Speaker 1: all the planets, like when you look at Jupiter, right, 207 00:10:49,520 --> 00:10:52,080 Speaker 1: that is reflected light from the Sun. Those photons have 208 00:10:52,200 --> 00:10:54,559 Speaker 1: all shot out from the Sun, hit Jupiter and then 209 00:10:54,640 --> 00:10:58,080 Speaker 1: come back to your eyeball. Right, Yeah, that's pretty cool 210 00:10:58,280 --> 00:11:00,000 Speaker 1: to think about it. But then do the photons became 211 00:11:00,080 --> 00:11:03,720 Speaker 1: um Jupiter photons? You know, like technically right, it's not 212 00:11:03,800 --> 00:11:06,600 Speaker 1: the same photons that came from the Sun, Like Jupiter 213 00:11:06,640 --> 00:11:09,480 Speaker 1: absorbed those photons from the Sun, did some something that 214 00:11:09,520 --> 00:11:13,560 Speaker 1: we might talk about later, and then emitted its own photons. Yeah, 215 00:11:13,600 --> 00:11:16,760 Speaker 1: it's complicated actually, Um, what happens when a photon hits 216 00:11:16,760 --> 00:11:19,960 Speaker 1: the surface, it can either get absorbed and then later 217 00:11:20,160 --> 00:11:22,839 Speaker 1: re emitted, but that you would really call emission, or 218 00:11:22,920 --> 00:11:27,040 Speaker 1: can actually get reflected right and quantum mechanically to understand 219 00:11:27,040 --> 00:11:30,320 Speaker 1: what happens during reflection is a whole other rabbit hole, 220 00:11:30,320 --> 00:11:32,600 Speaker 1: which would take a whole other podcast, which we're planning 221 00:11:32,679 --> 00:11:34,960 Speaker 1: to do in a few weeks actually. But so those 222 00:11:34,960 --> 00:11:38,680 Speaker 1: photons are sort of really just still like stellar photons 223 00:11:38,800 --> 00:11:42,040 Speaker 1: that have been reflected off of Jupiter. If something absorbs 224 00:11:42,120 --> 00:11:44,560 Speaker 1: the photons and then like gets hotter and emits it. 225 00:11:44,840 --> 00:11:47,280 Speaker 1: That's really a different kind of process. They are pretty 226 00:11:47,280 --> 00:11:52,560 Speaker 1: stellar photons. They're fantastic, fantastic. But you know, like you 227 00:11:52,600 --> 00:11:55,560 Speaker 1: see from stars, that's actually emitted from that star, right, 228 00:11:55,640 --> 00:11:58,080 Speaker 1: those stars are glowing. And so when we say something 229 00:11:58,200 --> 00:12:00,520 Speaker 1: is glowing, you really mean it's emitting its own photons. 230 00:12:00,559 --> 00:12:03,800 Speaker 1: It's not just like reflecting somebody else's photons. But today 231 00:12:03,800 --> 00:12:06,000 Speaker 1: we're sort of talking about things here on Earth that 232 00:12:06,120 --> 00:12:08,320 Speaker 1: sort of glow into visible light spectrum sort of on 233 00:12:08,360 --> 00:12:10,600 Speaker 1: their own, without any kind of battery or any light 234 00:12:10,679 --> 00:12:12,800 Speaker 1: reflecting on them. And so we're going to start with 235 00:12:12,880 --> 00:12:17,360 Speaker 1: things in chemistry and biology because we love chemistry and biology. 236 00:12:17,600 --> 00:12:20,680 Speaker 1: We do love chemistry and biology and chemists and biologists, right, 237 00:12:20,720 --> 00:12:25,640 Speaker 1: they're wonderful people. It's funny how we have to say 238 00:12:25,640 --> 00:12:29,880 Speaker 1: that physics. I'm not overcompensate anying at all. You know, 239 00:12:30,400 --> 00:12:33,000 Speaker 1: they're lovely people. But yes, there are things in biology 240 00:12:33,120 --> 00:12:35,360 Speaker 1: that glow in the dark, like algae, right, and and 241 00:12:35,520 --> 00:12:40,040 Speaker 1: some fungi absolutely, And so this is what we call bioluminescence. 242 00:12:40,400 --> 00:12:43,640 Speaker 1: And this is essentially just like some critter that has 243 00:12:43,760 --> 00:12:46,640 Speaker 1: energy stored inside of it and then releasing that energy 244 00:12:46,679 --> 00:12:49,440 Speaker 1: in terms of a photon. All right. Photons are just 245 00:12:49,520 --> 00:12:52,920 Speaker 1: like little units of energy, and when a chemical reaction 246 00:12:52,960 --> 00:12:55,400 Speaker 1: happens and energy is released, it can be released in 247 00:12:55,440 --> 00:12:57,960 Speaker 1: lots of ways. It can like heat up you know, 248 00:12:58,000 --> 00:13:01,280 Speaker 1: other molecules, or you can actually also just emit a photon. 249 00:13:01,480 --> 00:13:04,959 Speaker 1: And so that's what's happening in most cases inside these 250 00:13:05,000 --> 00:13:09,280 Speaker 1: bioluminescent properties, and they have a chemical reaction. Actually it's happening, 251 00:13:09,280 --> 00:13:13,360 Speaker 1: so it's biochemistry, and usually it's like oxygen reacting with 252 00:13:13,400 --> 00:13:17,280 Speaker 1: this thing called lucifering. It's the enzyme, and there's lucifer 253 00:13:17,360 --> 00:13:21,079 Speaker 1: in and lucifer aise and these things interact with oxygen 254 00:13:21,280 --> 00:13:25,400 Speaker 1: and then release a photon and form some new chemical compounds, well, 255 00:13:25,440 --> 00:13:29,320 Speaker 1: like lucifer like the fallen angel, or like lucid like light. 256 00:13:29,679 --> 00:13:31,840 Speaker 1: I think there's a connection there, Yeah, I think they 257 00:13:31,840 --> 00:13:35,160 Speaker 1: have the same route. All right. Interesting, So, like all 258 00:13:35,520 --> 00:13:41,040 Speaker 1: bioluminescences is evils what you're saying, or at least this 259 00:13:41,280 --> 00:13:44,400 Speaker 1: ends I'm called lucifer Ese. This is a surprisingly HALLOWEENI 260 00:13:44,480 --> 00:13:46,920 Speaker 1: themed episode, isn't it. Oh my goodness, are you in 261 00:13:46,960 --> 00:13:50,520 Speaker 1: costume right now? I'm dressed up as a physicist today. 262 00:13:51,360 --> 00:13:55,480 Speaker 1: Could let me get sandals, shorts, a T shirt or 263 00:13:55,559 --> 00:13:57,760 Speaker 1: is a T shirt optional? No comment? But you know 264 00:13:57,840 --> 00:14:00,480 Speaker 1: this happens in lots of different kinds of creature. You 265 00:14:00,520 --> 00:14:03,080 Speaker 1: have like bacteria that can do it. You have bugs 266 00:14:03,080 --> 00:14:05,719 Speaker 1: that can do it, like fireflies. You have fung gui 267 00:14:05,920 --> 00:14:08,600 Speaker 1: that can do it. A deep sea squids can do it. 268 00:14:08,760 --> 00:14:10,920 Speaker 1: You've probably seen pictures of those fish that have like 269 00:14:10,960 --> 00:14:13,600 Speaker 1: a little lantern that they have in front of themselves 270 00:14:13,600 --> 00:14:15,880 Speaker 1: to attract craters to eat. Yeah. Are you saying that 271 00:14:15,920 --> 00:14:19,000 Speaker 1: those all work with the same mechanism, the same enzyme 272 00:14:19,200 --> 00:14:22,080 Speaker 1: or like a similar enzyme. They're all very similar. There's 273 00:14:22,120 --> 00:14:26,640 Speaker 1: like forty different ways that this has evolved independently, and 274 00:14:26,680 --> 00:14:29,640 Speaker 1: they all use some variety of a lucifer in or 275 00:14:29,640 --> 00:14:33,400 Speaker 1: a lucifer ase, though it varies pretty widely between the species. Well, 276 00:14:33,400 --> 00:14:35,280 Speaker 1: it's pretty cool, and I think the point is that 277 00:14:35,320 --> 00:14:38,640 Speaker 1: they're expending energy, right. There's like using oxygen and they're 278 00:14:38,640 --> 00:14:40,800 Speaker 1: probably using some kind of sugar right to sort of 279 00:14:40,840 --> 00:14:43,760 Speaker 1: make this chemical reaction work. Yeah, Usually it starts out 280 00:14:43,800 --> 00:14:46,640 Speaker 1: with you know, your typical energy carrying molecule a t 281 00:14:46,840 --> 00:14:49,440 Speaker 1: P in the body and then it just converts that 282 00:14:49,600 --> 00:14:52,560 Speaker 1: energy into something else, which becomes a photon. And I 283 00:14:52,600 --> 00:14:54,480 Speaker 1: guess a big question is kind of why they do 284 00:14:54,560 --> 00:14:56,600 Speaker 1: those things. I guess just to sort of see things 285 00:14:56,800 --> 00:14:59,520 Speaker 1: in the dark or be able to communicate in the dark. 286 00:14:59,720 --> 00:15:02,760 Speaker 1: It's thing that the biologists speculate a lot. In some cases, 287 00:15:02,880 --> 00:15:05,880 Speaker 1: they do it to communicate like toxicity, the way like 288 00:15:05,960 --> 00:15:08,440 Speaker 1: a plant might be brightly colored or an insect might 289 00:15:08,480 --> 00:15:10,520 Speaker 1: be brightly colored to say like hey, watch out, stay 290 00:15:10,560 --> 00:15:12,880 Speaker 1: away from me. In other cases, they use it to 291 00:15:12,920 --> 00:15:15,960 Speaker 1: attract prey, like the lantern fish, you know, use it 292 00:15:16,000 --> 00:15:18,840 Speaker 1: to draw things to it because some microbes are attracted 293 00:15:18,840 --> 00:15:21,560 Speaker 1: to light. And so there's lots of different reasons, you know, 294 00:15:21,600 --> 00:15:24,080 Speaker 1: some of them to use this to communicate, like fireflies 295 00:15:24,160 --> 00:15:26,440 Speaker 1: or you know, for mating dances. So there's a really 296 00:15:26,480 --> 00:15:29,720 Speaker 1: wide variety of uses across the various creatures that do 297 00:15:29,840 --> 00:15:34,000 Speaker 1: bioluminous Interesting and you're saying they all evolved this independently, 298 00:15:34,200 --> 00:15:36,040 Speaker 1: like they all came up with the same solution, but 299 00:15:36,160 --> 00:15:38,600 Speaker 1: they hadn't talked to each other about it. Yeah, they 300 00:15:38,600 --> 00:15:41,600 Speaker 1: don't have a single common evolutionary history, which means that 301 00:15:41,640 --> 00:15:44,720 Speaker 1: it's something that's not that hard to evolve or something 302 00:15:44,760 --> 00:15:47,400 Speaker 1: that's pretty useful, And it's something I think biologists have 303 00:15:47,440 --> 00:15:50,000 Speaker 1: sort of learned to hack to write, Like they can 304 00:15:50,040 --> 00:15:53,520 Speaker 1: now like tweet the DNA of something or bacteria or 305 00:15:53,520 --> 00:15:56,080 Speaker 1: something and make it glow right, Yeah, exactly. It's not 306 00:15:56,160 --> 00:15:58,800 Speaker 1: that complicated a process, so they can sort of engineer 307 00:15:58,840 --> 00:16:01,120 Speaker 1: it into something, which means in the future, you know, 308 00:16:01,160 --> 00:16:03,680 Speaker 1: maybe you'll be able to bio hack your body into 309 00:16:03,680 --> 00:16:06,880 Speaker 1: glowing in the dark if you'd want that, or your 310 00:16:06,960 --> 00:16:10,160 Speaker 1: kids so you can keep on hall. That would be 311 00:16:10,200 --> 00:16:13,160 Speaker 1: pretty useful, just like give him a quick drink thank 312 00:16:13,160 --> 00:16:14,920 Speaker 1: you in the dark. Probably there's be an app on 313 00:16:14,960 --> 00:16:16,920 Speaker 1: your phone you can like turn your kid various colors, 314 00:16:16,960 --> 00:16:19,120 Speaker 1: you know, like where's my kid? Where is the playground 315 00:16:19,240 --> 00:16:22,080 Speaker 1: or something? Yeah, and you can change their color on 316 00:16:22,120 --> 00:16:25,240 Speaker 1: the app. That would be pretty handy. I know. Then 317 00:16:25,280 --> 00:16:28,920 Speaker 1: hackers take over and everybody's kids are just like blinking constantly. 318 00:16:29,200 --> 00:16:31,240 Speaker 1: That would be crazy. It seems like a bad idea, 319 00:16:31,720 --> 00:16:33,760 Speaker 1: or you get a raise on everyone's like as these 320 00:16:33,800 --> 00:16:38,280 Speaker 1: fun patterns in your skin, But there are actual technological applications. 321 00:16:38,360 --> 00:16:41,520 Speaker 1: It turns out that miners knew that some fish had 322 00:16:41,520 --> 00:16:44,400 Speaker 1: a very faint glow in them, and even after the 323 00:16:44,440 --> 00:16:48,240 Speaker 1: fish were dead, this process continued in their skins, and 324 00:16:48,280 --> 00:16:51,800 Speaker 1: so miners used to take dried fish skins down into 325 00:16:51,840 --> 00:16:54,440 Speaker 1: the mines with them as a sort of very very 326 00:16:54,520 --> 00:16:57,640 Speaker 1: faint lamp. And your eyeballs are so powerful that even 327 00:16:57,680 --> 00:17:00,440 Speaker 1: a very small source of light and a deep dark 328 00:17:00,760 --> 00:17:02,920 Speaker 1: is enough to sort of show you how to get around. 329 00:17:02,960 --> 00:17:05,359 Speaker 1: And an advantage of course in the deep caves not 330 00:17:05,440 --> 00:17:08,320 Speaker 1: to have like an open flame something that's consuming oxygen 331 00:17:08,359 --> 00:17:12,399 Speaker 1: and making smoke. Oh interesting, Yeah, although I imagine, you know, 332 00:17:12,440 --> 00:17:15,600 Speaker 1: taking dead fish into a very close and cramped quarter, 333 00:17:16,320 --> 00:17:19,000 Speaker 1: probably it becomes a bad idea in a short while. 334 00:17:19,119 --> 00:17:22,520 Speaker 1: There's always trade offs, all right. So that's bioluminescence, how 335 00:17:23,200 --> 00:17:25,640 Speaker 1: living creatures make light in the dark. But there's also 336 00:17:25,720 --> 00:17:27,800 Speaker 1: sort of the chemistry of it, right, Like we can 337 00:17:27,840 --> 00:17:31,080 Speaker 1: have glowst eggs, and we can have those sticky things 338 00:17:31,119 --> 00:17:33,600 Speaker 1: that glow in the dark and glow in the dark, 339 00:17:33,640 --> 00:17:36,040 Speaker 1: skulls and that that Halloween. How do those work? There's 340 00:17:36,040 --> 00:17:39,800 Speaker 1: a lot of ways that you can have chemo luminescence. Essentially, 341 00:17:39,840 --> 00:17:43,159 Speaker 1: you just need any sort of reaction that releases energy, 342 00:17:43,560 --> 00:17:45,879 Speaker 1: and sometimes it releases energy in terms of light and 343 00:17:45,880 --> 00:17:48,840 Speaker 1: not just heat. And so these are pretty simple reactions. 344 00:17:48,960 --> 00:17:51,439 Speaker 1: What's happening inside those things that you have like a 345 00:17:51,440 --> 00:17:55,240 Speaker 1: little glass vial that's separating two different chemicals that when 346 00:17:55,240 --> 00:17:57,720 Speaker 1: they come together, they react and they give off some 347 00:17:57,800 --> 00:18:01,280 Speaker 1: of their energy. Typically it's like hydrogen peroxide and then 348 00:18:01,400 --> 00:18:03,760 Speaker 1: some sort of activator chemical, and so you know how 349 00:18:03,840 --> 00:18:05,800 Speaker 1: you have to like bend those things and snap them 350 00:18:06,160 --> 00:18:08,359 Speaker 1: so that the two things then mix and form that 351 00:18:08,480 --> 00:18:11,879 Speaker 1: chemical reaction. Interesting, and so what's happening, Like the molecules 352 00:18:11,880 --> 00:18:15,520 Speaker 1: of one chemical are reacting with the other molecules, and 353 00:18:15,520 --> 00:18:19,280 Speaker 1: then somehow that process, as they rearranged themselves somehow releases 354 00:18:19,480 --> 00:18:23,359 Speaker 1: a photon. The end product requires less energy to build 355 00:18:23,640 --> 00:18:27,239 Speaker 1: than the actual ingredients, and so you've left over energy. Right, 356 00:18:27,240 --> 00:18:29,520 Speaker 1: It's like these two things have like fallen in together 357 00:18:29,680 --> 00:18:32,760 Speaker 1: into like a little potential. Well, so there's leftover energy 358 00:18:32,800 --> 00:18:34,840 Speaker 1: which is admitted in terms of a photon, and so 359 00:18:34,880 --> 00:18:37,800 Speaker 1: that's chemo and bioluminescence. That's pretty cool, all right, So 360 00:18:37,880 --> 00:18:41,000 Speaker 1: let's get into the things that glow in the dark 361 00:18:41,040 --> 00:18:44,199 Speaker 1: in other ways using physics. But first let's take a 362 00:18:44,240 --> 00:19:00,320 Speaker 1: quick break. All right, we're talking about things that glow 363 00:19:00,440 --> 00:19:02,760 Speaker 1: in the dark in a fun, fun way, right, not 364 00:19:02,800 --> 00:19:06,000 Speaker 1: in a scary way, that's right, and a sort of joyful, 365 00:19:06,040 --> 00:19:07,760 Speaker 1: you're gonna eat chocolate at the end of this night, 366 00:19:07,800 --> 00:19:11,480 Speaker 1: halloweeny sort of way. Yeah, probably too much. So we 367 00:19:11,520 --> 00:19:14,600 Speaker 1: talked about animals and bacteria and fun guy that glow 368 00:19:14,640 --> 00:19:16,600 Speaker 1: in the dark and how to do that with chemicals. 369 00:19:16,720 --> 00:19:18,920 Speaker 1: But then there's also things that seem to glow in 370 00:19:18,960 --> 00:19:21,800 Speaker 1: the dark without any kind of reactive reaction or any 371 00:19:21,840 --> 00:19:25,000 Speaker 1: kind of consumption of sugars or energy. Which are you know, 372 00:19:25,080 --> 00:19:28,000 Speaker 1: glow in the dark stickers and glow in the dark, 373 00:19:28,200 --> 00:19:30,520 Speaker 1: you know, decals and T shirts and things like that. 374 00:19:30,560 --> 00:19:32,960 Speaker 1: How did those work? Those are more physics, right, Yeah, 375 00:19:33,040 --> 00:19:35,200 Speaker 1: these are more physicals. And these are really cool because 376 00:19:35,200 --> 00:19:38,560 Speaker 1: they really are like little batteries. They're like storing the 377 00:19:38,720 --> 00:19:41,960 Speaker 1: energy from the sun and then slowly emitting its slowly 378 00:19:42,040 --> 00:19:44,280 Speaker 1: releasing it. So it really is sort of cool. Like 379 00:19:44,320 --> 00:19:45,960 Speaker 1: you know how you can charge these up? Right? You 380 00:19:45,960 --> 00:19:48,159 Speaker 1: put it in sunlight and then you rush into the 381 00:19:48,200 --> 00:19:50,639 Speaker 1: closet and it seems to glow really brightly and then 382 00:19:50,680 --> 00:19:53,240 Speaker 1: it fades very gradually, but it takes a long time, 383 00:19:53,400 --> 00:19:56,040 Speaker 1: and so it's i think of it like delayed reflection, 384 00:19:56,160 --> 00:19:58,600 Speaker 1: rather than just immediately reflecting all the light from the sun, 385 00:19:59,000 --> 00:20:01,119 Speaker 1: like it gathers at holds it, and it sort of 386 00:20:01,160 --> 00:20:03,280 Speaker 1: meters it out for you, the same way. You know 387 00:20:03,320 --> 00:20:05,520 Speaker 1: on Halloween you get a huge bucket of candy, but 388 00:20:05,560 --> 00:20:07,600 Speaker 1: your mom only lets you have one or two pieces 389 00:20:07,640 --> 00:20:10,480 Speaker 1: every day. We have two very different moms. I guess 390 00:20:10,760 --> 00:20:14,840 Speaker 1: my mom was not that concerned about my candy consumpt Yeah, 391 00:20:15,040 --> 00:20:17,840 Speaker 1: did you just eat it all herself? We just had 392 00:20:17,880 --> 00:20:21,800 Speaker 1: no rules, I think, Alis, I don't remember having any rules. 393 00:20:21,880 --> 00:20:23,480 Speaker 1: And is that the way you're raising your kids? Eat 394 00:20:23,520 --> 00:20:25,159 Speaker 1: as much candi as you like. Whenever you're like no, 395 00:20:25,359 --> 00:20:28,200 Speaker 1: of course he turned into the worst of yourself as 396 00:20:28,240 --> 00:20:30,560 Speaker 1: a parent. We we meet her up throughout the year. 397 00:20:30,640 --> 00:20:32,639 Speaker 1: All right, well, there you go. That's a good model 398 00:20:32,720 --> 00:20:36,159 Speaker 1: for the phosphorescence process which is happening and glow in 399 00:20:36,200 --> 00:20:38,439 Speaker 1: the dark toys. So what's happening here is that the 400 00:20:38,480 --> 00:20:41,320 Speaker 1: photon is hitting the object and it's in some low 401 00:20:41,440 --> 00:20:44,560 Speaker 1: energy state and absorbs that photon. R It doesn't just reflected, 402 00:20:44,520 --> 00:20:47,320 Speaker 1: it absorbs it, which means that like some electron in 403 00:20:47,359 --> 00:20:50,320 Speaker 1: that material now has more energy than it did before. 404 00:20:50,520 --> 00:20:53,000 Speaker 1: And that's not that unusual. But what happens here is 405 00:20:53,000 --> 00:20:57,120 Speaker 1: that the electron doesn't just immediately then release that energy. Instead, 406 00:20:57,160 --> 00:20:59,600 Speaker 1: it gets trapped. It's sort of like you've pushed the 407 00:20:59,640 --> 00:21:02,160 Speaker 1: electro up a hill and then before it can roll 408 00:21:02,200 --> 00:21:05,080 Speaker 1: back down, it gets caught on some ledge or something 409 00:21:05,080 --> 00:21:06,720 Speaker 1: and it has to hang out there for a while, 410 00:21:06,880 --> 00:21:09,080 Speaker 1: and it's very hard for it to get off that ledge. 411 00:21:09,280 --> 00:21:11,600 Speaker 1: And so you have this like pile of electrons stuck 412 00:21:11,640 --> 00:21:14,280 Speaker 1: up on that ledge, storing that energy, and occasionally one 413 00:21:14,320 --> 00:21:18,040 Speaker 1: will drop down and give off a photon. Interesting, and now, 414 00:21:18,119 --> 00:21:21,239 Speaker 1: is it like one photon per atom, or like one 415 00:21:21,280 --> 00:21:24,640 Speaker 1: electron per atom, or can like an atom store multiple 416 00:21:25,000 --> 00:21:27,159 Speaker 1: photon You can't really think about it in terms of 417 00:21:27,200 --> 00:21:29,960 Speaker 1: atoms because these are objects. So it's really like a lattice, 418 00:21:30,240 --> 00:21:32,600 Speaker 1: and the electrons are not really like held onto an 419 00:21:32,600 --> 00:21:36,440 Speaker 1: individual atom. So these electrons are like flowing around this crystal, 420 00:21:36,480 --> 00:21:39,120 Speaker 1: this lattice of whatever material it is that that you're 421 00:21:39,160 --> 00:21:41,280 Speaker 1: thinking about. You know, when we think about crystal, you 422 00:21:41,280 --> 00:21:44,040 Speaker 1: think of like a really hard firm object, but really 423 00:21:44,080 --> 00:21:46,119 Speaker 1: any solid you can think about in terms of a 424 00:21:46,160 --> 00:21:49,240 Speaker 1: crystal or a lattice. It's like a mesh of atoms 425 00:21:49,240 --> 00:21:52,600 Speaker 1: that are all woven together, and the electrons jump happily around. 426 00:21:52,760 --> 00:21:55,560 Speaker 1: And so what happens here is like an individual electron 427 00:21:55,800 --> 00:21:58,639 Speaker 1: gets energy and then it's like flowing freely, but it 428 00:21:58,680 --> 00:22:01,280 Speaker 1: can get stuck, like the is a defect in the lattice, 429 00:22:01,440 --> 00:22:04,000 Speaker 1: or you know, whether bonds are not perfect, or there's 430 00:22:04,040 --> 00:22:06,600 Speaker 1: like some doping materials some other kind of thing which 431 00:22:06,600 --> 00:22:09,439 Speaker 1: sort of breaks the lattice, and electrons can get stuck 432 00:22:09,440 --> 00:22:11,600 Speaker 1: in those little holes and then they have to wait 433 00:22:11,600 --> 00:22:13,480 Speaker 1: for like a little bit of heat or something else 434 00:22:13,520 --> 00:22:15,320 Speaker 1: to sort of knock them out of that hole and 435 00:22:15,440 --> 00:22:17,680 Speaker 1: down to a lower energy so they can give off 436 00:22:17,720 --> 00:22:22,240 Speaker 1: that light. And that's why the light is emitted over time. Interesting, 437 00:22:22,359 --> 00:22:25,440 Speaker 1: But then what happens to the photons? Do they like disappear, 438 00:22:25,520 --> 00:22:28,320 Speaker 1: they get transformed into a different kind of energy. What 439 00:22:28,480 --> 00:22:31,120 Speaker 1: what happens to the actual photon? So the initial photon, 440 00:22:31,280 --> 00:22:33,840 Speaker 1: it goes into the energy of the electron, right, and 441 00:22:33,880 --> 00:22:36,879 Speaker 1: then the electron has more energy, is like whizzing around 442 00:22:36,920 --> 00:22:39,240 Speaker 1: inside the lattice. When we say it's trapped, we don't 443 00:22:39,280 --> 00:22:42,600 Speaker 1: mean it's like physically stuck in a particular physical state. 444 00:22:42,640 --> 00:22:45,359 Speaker 1: We mean that it's like stuck in a higher energy state, 445 00:22:45,760 --> 00:22:48,720 Speaker 1: like can't release its energy. It's a it's stuck in 446 00:22:48,760 --> 00:22:51,760 Speaker 1: a state where it's very difficult to transition back down 447 00:22:51,800 --> 00:22:54,000 Speaker 1: to the lower state. You know, you can think about 448 00:22:54,000 --> 00:22:56,119 Speaker 1: these quantum states is sort of like a ladder, but 449 00:22:56,280 --> 00:22:58,800 Speaker 1: really it's not always easy to go up or down 450 00:22:59,119 --> 00:23:02,080 Speaker 1: the connections tween these two ladders. So weach require some 451 00:23:02,200 --> 00:23:05,400 Speaker 1: kind of interaction, you know, some sort of forces involved 452 00:23:05,440 --> 00:23:07,480 Speaker 1: in going from one part of the ladder to the 453 00:23:07,480 --> 00:23:09,880 Speaker 1: other part of the ladder, and sometimes those things are 454 00:23:09,960 --> 00:23:12,520 Speaker 1: difficult to happen, and so you can get stuck in 455 00:23:12,560 --> 00:23:15,800 Speaker 1: an upper state and very slowly the electrons can leak 456 00:23:15,880 --> 00:23:18,160 Speaker 1: down to the lower state. So that's what's happening here, 457 00:23:18,200 --> 00:23:20,400 Speaker 1: is that the process that takes the electron, that lets 458 00:23:20,440 --> 00:23:23,240 Speaker 1: it release its energy down to the lower state, is rare. 459 00:23:23,280 --> 00:23:25,760 Speaker 1: It's not like it could happen all the time, and 460 00:23:25,800 --> 00:23:27,919 Speaker 1: so a lot of the electrons are just like, you know, 461 00:23:28,040 --> 00:23:30,479 Speaker 1: whizzing around really excited, like kids that have had too 462 00:23:30,560 --> 00:23:33,920 Speaker 1: much candy, and they can't let that energy go. I see. 463 00:23:33,960 --> 00:23:36,600 Speaker 1: It's like it captures electrons easily, but it sort of 464 00:23:36,680 --> 00:23:39,440 Speaker 1: doles them out more rarely, and so that's why you 465 00:23:39,440 --> 00:23:42,280 Speaker 1: can sort of store light in a way, like you 466 00:23:42,400 --> 00:23:43,960 Speaker 1: charge in it in the sunlight and then you take 467 00:23:43,960 --> 00:23:46,239 Speaker 1: it into the dark room and it slowly gives us 468 00:23:46,320 --> 00:23:50,000 Speaker 1: those photons it absorbed. Yeah, Like imagine a huge bowl 469 00:23:50,160 --> 00:23:52,159 Speaker 1: with a tiny little hole at the bottom and you 470 00:23:52,200 --> 00:23:54,239 Speaker 1: fill it with ping pong balls. You're not gonna get 471 00:23:54,280 --> 00:23:56,199 Speaker 1: all the ping pong balls out at once. They're all 472 00:23:56,200 --> 00:23:58,040 Speaker 1: going to dribble out one at a time because the 473 00:23:58,040 --> 00:23:59,960 Speaker 1: size of the hole is small. And so that's the said, 474 00:24:00,000 --> 00:24:02,040 Speaker 1: see what's happening. And so that's how most glow in 475 00:24:02,080 --> 00:24:04,480 Speaker 1: the dark toys and stickers work. They all use the 476 00:24:04,520 --> 00:24:07,040 Speaker 1: same material or are there different materials that do this? 477 00:24:07,200 --> 00:24:08,960 Speaker 1: There are lots of different materials that can do this. 478 00:24:09,200 --> 00:24:12,680 Speaker 1: But the process in general is called phosphorescence. It's called 479 00:24:12,760 --> 00:24:16,160 Speaker 1: fluorescence if you just absorb and immediately re emit. It's 480 00:24:16,200 --> 00:24:19,239 Speaker 1: called phosphorescence if you absorb and you hang onto it 481 00:24:19,280 --> 00:24:21,560 Speaker 1: for a little while and then you emit. And so 482 00:24:21,600 --> 00:24:24,480 Speaker 1: it's phosphorescence that makes like the hands on your watch 483 00:24:24,520 --> 00:24:27,600 Speaker 1: glow or your little plastic toy glow or whatever it is. 484 00:24:27,600 --> 00:24:32,240 Speaker 1: Anything that needs to be charged by sunlight is phosphorescence. Interesting, 485 00:24:32,320 --> 00:24:35,520 Speaker 1: is it related to phosphor. Yeah, well, confusingly, something which 486 00:24:35,560 --> 00:24:40,120 Speaker 1: is a phosphor is anything which is either fluorescent or phosphorescent. 487 00:24:40,600 --> 00:24:43,720 Speaker 1: So that's a confusing set of names there. But the 488 00:24:43,720 --> 00:24:47,040 Speaker 1: phosphor is anything essentially that just glows. And I guess 489 00:24:47,040 --> 00:24:50,720 Speaker 1: can it trap energy in other ways or only through sunlight? Like? 490 00:24:50,800 --> 00:24:53,480 Speaker 1: Can I stick it in the microwave and then they'll glow, 491 00:24:53,600 --> 00:24:55,520 Speaker 1: or rub it really hard or put it over a 492 00:24:55,560 --> 00:24:57,760 Speaker 1: flame and they'll glow, you know what I mean? Or 493 00:24:57,920 --> 00:25:00,760 Speaker 1: is it only able to store energy from sunlight? That's 494 00:25:00,800 --> 00:25:02,879 Speaker 1: the most efficient way for it to happen, because what 495 00:25:02,960 --> 00:25:05,080 Speaker 1: you want is for the electrons to get their energy. 496 00:25:05,359 --> 00:25:07,879 Speaker 1: You don't want to break up the lattice itself. If 497 00:25:07,920 --> 00:25:09,720 Speaker 1: you put this thing in the microwave, you're gonna melt it. 498 00:25:09,720 --> 00:25:12,199 Speaker 1: You're gonna change the chemical composition. It's no longer going 499 00:25:12,240 --> 00:25:15,119 Speaker 1: to be that lattice that can hold that energy in 500 00:25:15,119 --> 00:25:17,680 Speaker 1: this particular state and admit it over time. So you 501 00:25:17,720 --> 00:25:20,040 Speaker 1: can destroy by heating it up. Yes, you will be 502 00:25:20,080 --> 00:25:23,200 Speaker 1: giving energy to those electrons, but the whole process relies 503 00:25:23,200 --> 00:25:25,480 Speaker 1: on the electrons moving through this lattice, and if you 504 00:25:25,520 --> 00:25:28,760 Speaker 1: destroy that lattice, then you've you've messed it up. I see. 505 00:25:28,800 --> 00:25:30,439 Speaker 1: So don't stick your glow in the darks in the 506 00:25:30,440 --> 00:25:34,880 Speaker 1: microwave is the main takeaway here today. That's right. Physics 507 00:25:34,880 --> 00:25:37,199 Speaker 1: tells you don't mark or weave random stuff, all right. 508 00:25:37,240 --> 00:25:39,600 Speaker 1: So those are phosphorescent glow in the dark toys. But 509 00:25:39,640 --> 00:25:41,840 Speaker 1: there are other ways in which physics can make you 510 00:25:41,840 --> 00:25:43,640 Speaker 1: glow in the dark, right, And some of them are 511 00:25:43,840 --> 00:25:45,919 Speaker 1: kind of intense, that's right. If you have like an 512 00:25:45,960 --> 00:25:49,000 Speaker 1: old fashioned glow in the dark, watch it might have 513 00:25:49,119 --> 00:25:51,920 Speaker 1: hands that glow in the dark all the time without 514 00:25:52,040 --> 00:25:54,920 Speaker 1: needing to be charged by sunlight. And that's particular and 515 00:25:55,000 --> 00:25:59,240 Speaker 1: kind of scary process because that's actually radioactive decay, you know. 516 00:25:59,320 --> 00:26:04,040 Speaker 1: That's something Some elements are not stable, like uranium. For example. 517 00:26:04,359 --> 00:26:06,480 Speaker 1: Uranium hangs out, but it doesn't hang out for the 518 00:26:06,520 --> 00:26:09,399 Speaker 1: whole life of the universe. Eventually it falls apart, and 519 00:26:09,480 --> 00:26:12,359 Speaker 1: it falls apart and gives off some energy. And in 520 00:26:12,400 --> 00:26:15,760 Speaker 1: some cases when these things decay, they emit very high 521 00:26:15,920 --> 00:26:20,480 Speaker 1: energy photons like cobalt sixty or nickel sixty. These are 522 00:26:20,600 --> 00:26:23,960 Speaker 1: unstable isotopes and when they decay they give off gamma 523 00:26:24,040 --> 00:26:26,520 Speaker 1: raise whoa. And they used to put this in like 524 00:26:26,920 --> 00:26:30,400 Speaker 1: regular watches for people. Yeah, regular watches for people. And 525 00:26:30,480 --> 00:26:32,600 Speaker 1: so you know, they wouldn't put like cobalt or nickel, 526 00:26:32,600 --> 00:26:35,480 Speaker 1: but they would use things like radium, which is pretty prevalent, 527 00:26:35,800 --> 00:26:39,439 Speaker 1: and a little bit of radium would give off essentially radiation, 528 00:26:39,720 --> 00:26:42,200 Speaker 1: and you know, gamma rays you can't see with your eyes. 529 00:26:42,240 --> 00:26:45,440 Speaker 1: These are photons, but they're very very high energy, which 530 00:26:45,440 --> 00:26:47,840 Speaker 1: means they're small wavelengths, so you can't see them. So 531 00:26:47,880 --> 00:26:50,600 Speaker 1: they would mix this with something else which can absorb 532 00:26:50,680 --> 00:26:53,840 Speaker 1: gamma raise and then emits at a different frequency, So 533 00:26:53,880 --> 00:26:58,199 Speaker 1: it's called wavelength shifting, like absorbs photon avoiding frequency, and 534 00:26:58,240 --> 00:27:01,440 Speaker 1: then it gives off photons of a ower frequency, which 535 00:27:01,480 --> 00:27:04,399 Speaker 1: you can see. It's like little physics batteries, right. You know, 536 00:27:04,440 --> 00:27:06,880 Speaker 1: you have energy stored in this radium and it's slowly 537 00:27:06,960 --> 00:27:09,879 Speaker 1: leaking out and gets transformed into visible light that your 538 00:27:09,880 --> 00:27:13,600 Speaker 1: eyeballs can see. WHOA, but aren't these watches dangerous? Like 539 00:27:13,640 --> 00:27:16,760 Speaker 1: doesn't the rada activity give you some sort of mutation 540 00:27:16,800 --> 00:27:19,000 Speaker 1: in your genes and stuff like that? Yeah? Absolutely, And 541 00:27:19,040 --> 00:27:21,280 Speaker 1: that's why they're not doing it so much anymore. You know, 542 00:27:21,480 --> 00:27:24,159 Speaker 1: these things I've been phased out. But radium used to 543 00:27:24,160 --> 00:27:26,520 Speaker 1: be treated a lot more casually. You know, the experiments 544 00:27:26,520 --> 00:27:29,919 Speaker 1: that Marie Curie did decades and decades ago, and she 545 00:27:30,040 --> 00:27:32,280 Speaker 1: worked in her lab for a long time, and now 546 00:27:32,320 --> 00:27:34,840 Speaker 1: her lab is so radioactive that you can't even go 547 00:27:34,880 --> 00:27:37,719 Speaker 1: inside it. So we're taking radiation much more seriously than 548 00:27:37,760 --> 00:27:39,720 Speaker 1: people used to. And so yeah, now we don't just 549 00:27:39,760 --> 00:27:43,600 Speaker 1: like casually paint things with radioactive paint because it's basically 550 00:27:43,640 --> 00:27:47,000 Speaker 1: cancer paint, well, or cancer at least in other ways. 551 00:27:48,440 --> 00:27:51,280 Speaker 1: There are still pretty dangerous chemicals and some paints. But 552 00:27:51,320 --> 00:27:54,439 Speaker 1: I guess the question is, like is all radiation dangerous? Like, 553 00:27:54,480 --> 00:27:57,920 Speaker 1: if it's just radiating photons, that's probably okay, right, It's 554 00:27:57,960 --> 00:28:01,480 Speaker 1: like when they radiate other heavier particles that that's the problem. 555 00:28:01,520 --> 00:28:04,040 Speaker 1: That's the part that gives you cancer. Right, Well, it 556 00:28:04,080 --> 00:28:06,560 Speaker 1: depends on whether or not it has enough energy to 557 00:28:06,600 --> 00:28:09,639 Speaker 1: penetrate your skin. Are various kinds of radiation. You can 558 00:28:09,760 --> 00:28:12,720 Speaker 1: radiate electrons, or you can really like a helium nucleus, 559 00:28:12,800 --> 00:28:15,200 Speaker 1: or you can radiate a photon. You might think how 560 00:28:15,280 --> 00:28:18,000 Speaker 1: dangerous could a photon B? But if a photon is 561 00:28:18,000 --> 00:28:20,240 Speaker 1: a gamma ray, which means it has a lot of energy, 562 00:28:20,440 --> 00:28:23,200 Speaker 1: then you can really penetrate your body, just like X rays. 563 00:28:23,440 --> 00:28:26,760 Speaker 1: X rays are also photons, but we're very careful with 564 00:28:26,960 --> 00:28:29,560 Speaker 1: X rays because we know that they cause mutations and 565 00:28:29,640 --> 00:28:32,239 Speaker 1: too many X rays will give you cancer, and so 566 00:28:32,280 --> 00:28:34,879 Speaker 1: you wouldn't want like something on your wrist which emits 567 00:28:35,000 --> 00:28:37,080 Speaker 1: X rays all the time. Gamma rays are in the 568 00:28:37,160 --> 00:28:40,360 Speaker 1: same category. They're ionizing radiation that can penetrate your body 569 00:28:40,360 --> 00:28:42,760 Speaker 1: and they can do damage right or like UV rays 570 00:28:42,840 --> 00:28:45,960 Speaker 1: right from the sun. That's why you need sun block. You. 571 00:28:46,080 --> 00:28:48,120 Speaker 1: V are a little bit lower energy than gamma rays, 572 00:28:48,160 --> 00:28:50,320 Speaker 1: but still dangerous, all right. So that's another way to 573 00:28:50,440 --> 00:28:53,280 Speaker 1: have something glow in the dark is they get radioactive 574 00:28:53,480 --> 00:28:55,400 Speaker 1: and have that radio activity kind of work it so 575 00:28:55,440 --> 00:28:58,440 Speaker 1: that it somehow emits visible light photons. Yeah, and there's 576 00:28:58,480 --> 00:29:00,800 Speaker 1: lots of different ways you can take advantage of radioactivity. 577 00:29:00,960 --> 00:29:04,080 Speaker 1: Remember that some of our awesome like robotic explorers around 578 00:29:04,080 --> 00:29:06,640 Speaker 1: the Solar System take advantage of the same property. They 579 00:29:06,640 --> 00:29:09,520 Speaker 1: have a chunk of radioactive material which is slowly decaying 580 00:29:09,880 --> 00:29:13,040 Speaker 1: and giving off energy in terms of photons or other radiation, 581 00:29:13,320 --> 00:29:16,240 Speaker 1: which is then captured and turned into electricity empowers those 582 00:29:16,360 --> 00:29:19,400 Speaker 1: rovers and those satellites. So it's also kind of awesome. 583 00:29:19,600 --> 00:29:21,880 Speaker 1: It's just not something you should have close to people, right, 584 00:29:21,960 --> 00:29:23,880 Speaker 1: And those that don't glow in the dark, right, like 585 00:29:23,920 --> 00:29:26,520 Speaker 1: they're in case in all this sort of material inside 586 00:29:26,520 --> 00:29:28,320 Speaker 1: of the battery, that's right. I don't think that those 587 00:29:28,360 --> 00:29:29,960 Speaker 1: things glow in the dark. That would be pretty cool 588 00:29:30,000 --> 00:29:32,080 Speaker 1: to glow in the dark, Mars Rover. I think it 589 00:29:32,080 --> 00:29:36,320 Speaker 1: has the flashlights, so it can't technically glow in the dark. 590 00:29:36,720 --> 00:29:39,120 Speaker 1: All right, Well, what's another way in which physics can 591 00:29:39,200 --> 00:29:41,880 Speaker 1: make things glow in the dark. As we were saying earlier, 592 00:29:41,920 --> 00:29:45,960 Speaker 1: almost everything in the universe does already actually glow, It 593 00:29:46,080 --> 00:29:48,880 Speaker 1: just might not be hot enough to glow in the 594 00:29:49,040 --> 00:29:51,760 Speaker 1: visible light spectrum. This is something in physics we call 595 00:29:51,920 --> 00:29:55,480 Speaker 1: black body radiation. By black body, we just mean something 596 00:29:55,480 --> 00:29:58,280 Speaker 1: that doesn't reflect any light, which absorbs all of the 597 00:29:58,400 --> 00:30:00,560 Speaker 1: energy of the light that hits it, and then amidst 598 00:30:00,640 --> 00:30:04,000 Speaker 1: light based on its temperature. And you're saying, everything in 599 00:30:04,040 --> 00:30:06,720 Speaker 1: the universe does this, right, Everything in the universe does 600 00:30:06,800 --> 00:30:09,440 Speaker 1: this exactly, And it depends on your temperature. The hotter 601 00:30:09,560 --> 00:30:13,000 Speaker 1: you are, the higher the frequency of the photons you emit. 602 00:30:13,200 --> 00:30:15,760 Speaker 1: The colder you are, the lower the frequency of the 603 00:30:16,040 --> 00:30:19,440 Speaker 1: photons you emit, and that's why, for example, the Earth glows, 604 00:30:19,640 --> 00:30:21,840 Speaker 1: but it doesn't glow in the visible spectrum like the 605 00:30:21,880 --> 00:30:26,520 Speaker 1: Sun does. The Sun very very hot on its surface 606 00:30:26,920 --> 00:30:30,360 Speaker 1: and it glows in the visible light. The Earth also glows, 607 00:30:30,720 --> 00:30:33,840 Speaker 1: but only in the infrareds. You need like special cameras 608 00:30:33,880 --> 00:30:36,840 Speaker 1: to see the Earth's glow. And I glow like That's 609 00:30:36,840 --> 00:30:38,680 Speaker 1: why you can see me in ninth vision, and I 610 00:30:38,720 --> 00:30:41,680 Speaker 1: look different from things around me because I'm hotter and 611 00:30:41,720 --> 00:30:44,920 Speaker 1: the spectrum that I emit has a higher frequency than 612 00:30:45,000 --> 00:30:48,360 Speaker 1: like the table next to me or the ground beneath me. Mmmm. 613 00:30:48,760 --> 00:30:50,920 Speaker 1: Just seeing like so like to an alien who could 614 00:30:50,960 --> 00:30:53,400 Speaker 1: see in the infrared, Earth would look like a star 615 00:30:53,560 --> 00:30:55,640 Speaker 1: kind of them one, but it would still glow in 616 00:30:55,680 --> 00:30:58,360 Speaker 1: the sky exactly. And that's why we build the James 617 00:30:58,400 --> 00:31:01,080 Speaker 1: web Space Telescope, which is gonna low very soon and 618 00:31:01,200 --> 00:31:03,240 Speaker 1: can see in the infrared, because we want to see 619 00:31:03,240 --> 00:31:06,080 Speaker 1: those planets. We don't just want to study things in 620 00:31:06,120 --> 00:31:08,240 Speaker 1: the universe that glow in the visible. We want to 621 00:31:08,240 --> 00:31:10,840 Speaker 1: see things that glow in infra red. So that's an 622 00:31:10,880 --> 00:31:13,800 Speaker 1: awesome telescope that's kept very very very cold, so it 623 00:31:13,840 --> 00:31:17,240 Speaker 1: can be sensitive to these very low energy photons coming 624 00:31:17,280 --> 00:31:20,320 Speaker 1: from for example, exo planets, so we can see how 625 00:31:20,320 --> 00:31:23,200 Speaker 1: hot those agians are, whether they're hot or not. That's right. 626 00:31:23,320 --> 00:31:25,479 Speaker 1: And you know you know this already because you know 627 00:31:25,560 --> 00:31:28,640 Speaker 1: that things glow different colors as they get hotter. Like 628 00:31:28,720 --> 00:31:30,800 Speaker 1: you have a chunk of metal, it can get red 629 00:31:30,800 --> 00:31:33,000 Speaker 1: hot and then it can get white hot. Right, so 630 00:31:33,040 --> 00:31:35,240 Speaker 1: we have a very intuitive sense for how things glow 631 00:31:35,320 --> 00:31:38,240 Speaker 1: differently as they get hot. And it just turns out 632 00:31:38,280 --> 00:31:41,000 Speaker 1: that that continues. You know, something that's super duper hot, 633 00:31:41,000 --> 00:31:43,600 Speaker 1: it starts to glow in the UV or starts to 634 00:31:43,640 --> 00:31:46,840 Speaker 1: give off X rays. You know why does the gas 635 00:31:46,920 --> 00:31:49,880 Speaker 1: around a black hole give off X rays because it's 636 00:31:49,920 --> 00:31:52,840 Speaker 1: super duper crazy hot. Well, I guess the question is 637 00:31:52,880 --> 00:31:55,720 Speaker 1: what's that mechanism? Like why is temperature related to the 638 00:31:55,720 --> 00:31:58,600 Speaker 1: freuencular light that's emitted by something? Or I guess even 639 00:31:58,600 --> 00:32:01,400 Speaker 1: a step further back, like why do things that are 640 00:32:01,400 --> 00:32:03,960 Speaker 1: hot glow at all? Yeah, it's a great question. It's 641 00:32:04,040 --> 00:32:06,920 Speaker 1: just basically entropy. You have a bunch of energy in 642 00:32:06,960 --> 00:32:09,600 Speaker 1: a small space and you have stuff nearby that doesn't 643 00:32:09,600 --> 00:32:12,200 Speaker 1: have as much energy, then that energy is going to transfer. 644 00:32:12,600 --> 00:32:15,120 Speaker 1: And one way for that to happen is for things 645 00:32:15,120 --> 00:32:18,320 Speaker 1: to emit photons. So basically, everything that has charged particles 646 00:32:18,320 --> 00:32:21,959 Speaker 1: inside of it, electrons or atoms or whatever, is constantly 647 00:32:22,000 --> 00:32:24,760 Speaker 1: just giving off photons. And so if you have something 648 00:32:24,840 --> 00:32:27,880 Speaker 1: nearby that isn't as hot, then it's going to be 649 00:32:27,960 --> 00:32:31,640 Speaker 1: accepting those photons. So basically, you know, electrons as they 650 00:32:31,680 --> 00:32:36,200 Speaker 1: move around are constantly just radiating away photons just because 651 00:32:36,200 --> 00:32:38,720 Speaker 1: their decaying, like decays is it's sort of like a 652 00:32:38,760 --> 00:32:42,000 Speaker 1: decaying process, like the electrons just suddenly like, hey, I 653 00:32:42,040 --> 00:32:44,880 Speaker 1: give up, I'm done with this universe. I'll just chill 654 00:32:44,920 --> 00:32:46,840 Speaker 1: out in a mid of photon sort of. It's sort 655 00:32:46,840 --> 00:32:49,520 Speaker 1: of like, you know, like a bath. You know, electrons 656 00:32:49,560 --> 00:32:52,400 Speaker 1: aren't just like flying around holding onto their energy. They're 657 00:32:52,400 --> 00:32:54,760 Speaker 1: constantly like transferring it back and forth to each other 658 00:32:54,800 --> 00:32:57,600 Speaker 1: and between themselves and the atoms nearby. And if you're 659 00:32:57,640 --> 00:33:00,320 Speaker 1: at an edge of an object, then some of those photons, 660 00:33:00,320 --> 00:33:02,959 Speaker 1: instead of getting like absorbed by another atom or absorbed 661 00:33:03,000 --> 00:33:06,000 Speaker 1: by another electron, just fly out into the universe with 662 00:33:06,160 --> 00:33:08,760 Speaker 1: the electron at the photon the photon. It's sort of 663 00:33:08,800 --> 00:33:10,880 Speaker 1: like if you're you know, if there's a party, everybody's 664 00:33:10,880 --> 00:33:12,640 Speaker 1: talking to each other everybody's sort of in the middle 665 00:33:12,680 --> 00:33:15,040 Speaker 1: of this soup of conversation. If you're in the outside 666 00:33:15,040 --> 00:33:16,800 Speaker 1: of the party, you're gonna hear some of that conversation 667 00:33:16,840 --> 00:33:20,000 Speaker 1: because some of those voices are pointed in your direction Accidentally, 668 00:33:20,240 --> 00:33:21,840 Speaker 1: it's not going to be as intense as if you're 669 00:33:21,840 --> 00:33:24,960 Speaker 1: actually inside of it. But always leaks out. Energy, always 670 00:33:25,000 --> 00:33:27,520 Speaker 1: spreads out through the universe, and this is just, you know, 671 00:33:27,560 --> 00:33:29,400 Speaker 1: another way for that to happen. But yeah, I guess 672 00:33:29,440 --> 00:33:30,960 Speaker 1: if you're at like at the edge of that party, 673 00:33:31,080 --> 00:33:32,880 Speaker 1: not that many people are talking to you, so you 674 00:33:32,960 --> 00:33:34,680 Speaker 1: might be like, yeah, I'll just go home and watch 675 00:33:34,720 --> 00:33:37,720 Speaker 1: some Netflix, and so you leave the party and so 676 00:33:37,840 --> 00:33:40,560 Speaker 1: like eventually the whole party sort of evaporates, Right, that's 677 00:33:40,560 --> 00:33:42,640 Speaker 1: the idea. Everybody just goes home and eat their Halloween 678 00:33:42,640 --> 00:33:45,200 Speaker 1: candy and silence eventually. Yeah, So that's kind of what's 679 00:33:45,240 --> 00:33:47,800 Speaker 1: what's happening in your body right now, which is like, 680 00:33:47,960 --> 00:33:50,840 Speaker 1: you know, some of the atoms and electrons at the surface, 681 00:33:50,880 --> 00:33:54,480 Speaker 1: they're just like, you know, spontaneously giving off photons. Yeah, 682 00:33:54,480 --> 00:33:57,880 Speaker 1: it's a spontaneous process of just like the radiative distribution 683 00:33:58,040 --> 00:34:02,120 Speaker 1: of entropy. Why does hotter body correspond to a higher 684 00:34:02,160 --> 00:34:04,800 Speaker 1: frequency of the light, did you emit Because higher frequency 685 00:34:04,920 --> 00:34:08,000 Speaker 1: is higher energy. So as the body gets hotter, right, is, 686 00:34:08,040 --> 00:34:10,840 Speaker 1: there's more energy stored inside of it than it's possible 687 00:34:10,880 --> 00:34:13,480 Speaker 1: for it to admit photons at higher energy. So it's 688 00:34:13,480 --> 00:34:15,600 Speaker 1: actually a whole spectrum. It's not like there's a single 689 00:34:15,600 --> 00:34:18,400 Speaker 1: wavelength emitted by a certain object based on its temperature. 690 00:34:18,520 --> 00:34:21,160 Speaker 1: It's a whole spectrum. Something it's really hot emits at 691 00:34:21,400 --> 00:34:25,239 Speaker 1: low frequencies and at high frequencies. Something that's cold only 692 00:34:25,280 --> 00:34:28,240 Speaker 1: emits the lower frequencies because it doesn't hap enough photons 693 00:34:28,280 --> 00:34:31,480 Speaker 1: inside of it to emit at the higher frequencies. Interesting. 694 00:34:31,640 --> 00:34:33,399 Speaker 1: So this is where it gets a little bit confusing too, 695 00:34:33,400 --> 00:34:36,160 Speaker 1: because sometimes what people call a star is really just 696 00:34:36,200 --> 00:34:39,840 Speaker 1: like a hot bodying space. Yeah, exactly. The future of 697 00:34:39,920 --> 00:34:43,040 Speaker 1: our star is to become something called a white dwarf. 698 00:34:43,360 --> 00:34:46,160 Speaker 1: When all the fusion has finished and it's blown out 699 00:34:46,160 --> 00:34:48,399 Speaker 1: a huge amount of its mass into space, the core 700 00:34:48,480 --> 00:34:51,319 Speaker 1: of it will collapse into a very heavy blov of 701 00:34:51,360 --> 00:34:54,640 Speaker 1: stuff that's not capable of fusing anymore, but it will 702 00:34:54,680 --> 00:34:57,319 Speaker 1: still be super duper hot. And this is what we 703 00:34:57,360 --> 00:34:59,480 Speaker 1: call a white dwarf. And you know, we call it 704 00:34:59,520 --> 00:35:01,760 Speaker 1: a star, or some people call it a stellar remnant. 705 00:35:01,960 --> 00:35:03,960 Speaker 1: It's gonna be really hot, and it's called a white 706 00:35:04,040 --> 00:35:06,840 Speaker 1: dwarf because it's gonna glow white hot. You know, I 707 00:35:06,880 --> 00:35:10,040 Speaker 1: think it's gonna be tens of thousands of degrees and 708 00:35:10,080 --> 00:35:12,239 Speaker 1: so it's going to be glowing into the universe and 709 00:35:12,280 --> 00:35:15,600 Speaker 1: looking like a star. But no fusion is happening inside 710 00:35:15,600 --> 00:35:18,440 Speaker 1: of it. It's just because it's hot, right, It's just 711 00:35:18,480 --> 00:35:20,600 Speaker 1: glowing because it's hot, the same way that like, you know, 712 00:35:20,719 --> 00:35:23,000 Speaker 1: metal that you've taken out of a forge glows because 713 00:35:23,040 --> 00:35:25,960 Speaker 1: it's hot, or a light bulb glows because it's hot. Right, 714 00:35:26,040 --> 00:35:28,920 Speaker 1: And but technically there is some sort of reaction going on, right, 715 00:35:28,920 --> 00:35:31,960 Speaker 1: things are breaking down, and so that's why it's emitting light. Well, 716 00:35:32,000 --> 00:35:35,400 Speaker 1: it's just sort of this spontaneous redistribution of energy. You know, 717 00:35:35,480 --> 00:35:37,640 Speaker 1: anything that's hot is going to glow and give off 718 00:35:37,680 --> 00:35:40,440 Speaker 1: its energy and cool down essentially, And the future of 719 00:35:40,480 --> 00:35:43,399 Speaker 1: these white dwarves is not that they're going to chemically change, right, 720 00:35:43,440 --> 00:35:45,800 Speaker 1: they have a lump of iron. It's gonna stay iron, 721 00:35:46,040 --> 00:35:48,759 Speaker 1: but they will cool down and in trillions of years 722 00:35:48,800 --> 00:35:53,160 Speaker 1: eventually become black dwarves. Well, so ironically, it'll still have 723 00:35:53,200 --> 00:35:56,120 Speaker 1: the same meaning. It will literally become a black body eventually. 724 00:35:56,200 --> 00:35:58,160 Speaker 1: All right, well, let's take it up a notch, Daniel, 725 00:35:58,200 --> 00:36:01,160 Speaker 1: and let's talk about bigger and crazier things in the 726 00:36:01,239 --> 00:36:03,800 Speaker 1: universe that glow in the dark, like black holes in 727 00:36:03,880 --> 00:36:19,120 Speaker 1: dark matter. But first, let's take another quick break. All right, 728 00:36:19,200 --> 00:36:23,080 Speaker 1: we're talking about things that glow in the dark, and ironically, 729 00:36:23,239 --> 00:36:25,880 Speaker 1: in this universe, things that have the name black and 730 00:36:26,000 --> 00:36:29,319 Speaker 1: dark also glow in the dark. That's right, it's weird 731 00:36:29,360 --> 00:36:31,680 Speaker 1: to think about black body is something that glows in 732 00:36:31,719 --> 00:36:35,319 Speaker 1: the dark, like the Sun is an almost perfect black body. Right. 733 00:36:35,480 --> 00:36:37,960 Speaker 1: It's just another example of physics using words that we 734 00:36:38,040 --> 00:36:41,000 Speaker 1: find familiar in ways that make no sense. What I mean, 735 00:36:41,040 --> 00:36:42,840 Speaker 1: the sun is a black body. The sun is a 736 00:36:42,880 --> 00:36:45,080 Speaker 1: black body. What they mean by that is that the 737 00:36:45,120 --> 00:36:47,920 Speaker 1: Sun absorbs almost any light that hits it. It doesn't 738 00:36:47,960 --> 00:36:51,759 Speaker 1: reflect any light. Black body just means no reflection. You 739 00:36:51,760 --> 00:36:54,600 Speaker 1: can absorb light, and you can admit light because you're hot, 740 00:36:54,760 --> 00:36:57,520 Speaker 1: but there's no reflection. So when you say we model 741 00:36:57,600 --> 00:36:59,640 Speaker 1: this as a black body, we just mean that there's 742 00:36:59,640 --> 00:37:02,480 Speaker 1: no selection and the Sun absorbs almost any light that 743 00:37:02,560 --> 00:37:04,879 Speaker 1: hits it. The Sun is not a good mirror. Yeah, 744 00:37:04,920 --> 00:37:07,040 Speaker 1: I guess any light that hits it just goes into 745 00:37:07,080 --> 00:37:09,919 Speaker 1: that crazy plasma that is inside of it, right, Yeah, 746 00:37:10,000 --> 00:37:12,040 Speaker 1: and heats it up and then it will emit again. 747 00:37:12,400 --> 00:37:14,680 Speaker 1: But it's not a reflection. All right. Well, I think 748 00:37:14,680 --> 00:37:17,279 Speaker 1: you're telling me earlier that black holes also glow in 749 00:37:17,280 --> 00:37:20,160 Speaker 1: the dark. Black holes do glow, which is super awesome, 750 00:37:20,280 --> 00:37:22,600 Speaker 1: And people might be familiar with this because the whole 751 00:37:22,640 --> 00:37:25,400 Speaker 1: idea of Hawking radiation. But I think it's interesting to 752 00:37:25,480 --> 00:37:28,680 Speaker 1: understand the origin of this idea, Like how did Hawking 753 00:37:28,800 --> 00:37:31,399 Speaker 1: come up with the concept that black holes might give 754 00:37:31,440 --> 00:37:34,920 Speaker 1: off radiation? And it came from thinking about the temperature 755 00:37:34,920 --> 00:37:38,319 Speaker 1: of things and how things glow, this connection between how 756 00:37:38,560 --> 00:37:41,640 Speaker 1: things that have temperature seemed to glow. So he and 757 00:37:41,719 --> 00:37:44,880 Speaker 1: his student, whose named Bekenstein, we're thinking about this, like 758 00:37:45,239 --> 00:37:49,719 Speaker 1: what is the thermodynamics of black holes? And so Hawkings 759 00:37:49,760 --> 00:37:52,960 Speaker 1: contributions to physics and the black holes is much more 760 00:37:52,960 --> 00:37:55,680 Speaker 1: than just like realizing that there might be some radiation 761 00:37:55,800 --> 00:37:58,680 Speaker 1: leaking at the side, is from thinking about black holes 762 00:37:58,719 --> 00:38:02,680 Speaker 1: in terms of thermodynamic quantities, like what is its temperature 763 00:38:02,840 --> 00:38:06,160 Speaker 1: and what is its entropy? And very quickly they realize 764 00:38:06,200 --> 00:38:09,480 Speaker 1: that black holes have to have some entropy because entropy 765 00:38:09,600 --> 00:38:12,520 Speaker 1: is conservad entry always increases in the universe, and when 766 00:38:12,520 --> 00:38:15,440 Speaker 1: something falls into a black hole, you can't just like 767 00:38:15,600 --> 00:38:18,200 Speaker 1: delete its entropy, which means the black holes have to 768 00:38:18,280 --> 00:38:21,160 Speaker 1: hold some entropy. And if they have an entropy, then 769 00:38:21,200 --> 00:38:23,759 Speaker 1: they have to have temperature. You're using entropy sort of 770 00:38:23,760 --> 00:38:26,839 Speaker 1: as a standing for like heat and energy. Well, they're 771 00:38:26,840 --> 00:38:30,319 Speaker 1: definitely connected, right. Remember, entropy is like a measure of 772 00:38:30,360 --> 00:38:32,960 Speaker 1: the disorder of a system sort of. It's like the 773 00:38:33,080 --> 00:38:36,960 Speaker 1: number of ways you can rearrange the microscopic state of 774 00:38:36,960 --> 00:38:40,360 Speaker 1: an object to be consistent with its macroscopic state. And 775 00:38:40,400 --> 00:38:42,920 Speaker 1: so something that has a lot of temperature is going 776 00:38:42,960 --> 00:38:44,480 Speaker 1: to have a lot of entropy because it'll be a 777 00:38:44,520 --> 00:38:46,799 Speaker 1: lot of different ways you can rearrange it. And so 778 00:38:46,880 --> 00:38:49,239 Speaker 1: if you have something and falls into a black hole, 779 00:38:49,560 --> 00:38:51,960 Speaker 1: it carries with it some entropy. It's sort of like 780 00:38:52,200 --> 00:38:55,160 Speaker 1: thinking about information, right, you know, where's the information for 781 00:38:55,280 --> 00:38:57,440 Speaker 1: something that falls into a black hole? Goes into the 782 00:38:57,440 --> 00:39:00,440 Speaker 1: black hole. So black holes have to have in formation, 783 00:39:00,520 --> 00:39:03,560 Speaker 1: and the folks that work on the black hole information paradox, 784 00:39:03,640 --> 00:39:06,640 Speaker 1: this question about what happens to information that falls inside 785 00:39:06,640 --> 00:39:08,400 Speaker 1: the black hole. They tend to think about it in 786 00:39:08,520 --> 00:39:11,400 Speaker 1: terms of entropy. Also basically talking said that, you know, 787 00:39:11,400 --> 00:39:13,600 Speaker 1: black holes are not just like a spot of nothing. 788 00:39:13,680 --> 00:39:15,839 Speaker 1: They have something to them, They have something to them, 789 00:39:16,000 --> 00:39:18,719 Speaker 1: they have some entropy, They have to have some temperature, 790 00:39:19,040 --> 00:39:21,360 Speaker 1: and if they have some temperature, they have to glow. 791 00:39:21,600 --> 00:39:26,000 Speaker 1: Because everything in the universe that interacts electromagnetically, right, everything 792 00:39:26,000 --> 00:39:29,160 Speaker 1: in the universe that has some energy localized into it 793 00:39:29,200 --> 00:39:31,840 Speaker 1: tends to give off some of that tends to radiate 794 00:39:31,880 --> 00:39:34,440 Speaker 1: that a way, just like a white dwarf, or just 795 00:39:34,520 --> 00:39:37,320 Speaker 1: like the sun, or just like that piece of metal 796 00:39:37,400 --> 00:39:39,560 Speaker 1: you stuck in a forge, or just like the Earth, 797 00:39:39,680 --> 00:39:42,200 Speaker 1: everything should glow. And so to sort of makes sense 798 00:39:42,200 --> 00:39:46,120 Speaker 1: of this, mathematically invented this whole field of black hole thermodynamics, 799 00:39:46,120 --> 00:39:49,120 Speaker 1: and out of it came this concept of Hawking radiation, 800 00:39:49,160 --> 00:39:51,840 Speaker 1: that even black holes give off radiation because they have 801 00:39:51,920 --> 00:39:55,200 Speaker 1: a non zero temperature. Right. But I guess the problem 802 00:39:55,280 --> 00:39:57,480 Speaker 1: is that, you know, black holes are supposed to be 803 00:39:57,480 --> 00:39:59,759 Speaker 1: things out of which nothing can come out. So even 804 00:39:59,800 --> 00:40:03,280 Speaker 1: if has you know, information or entroprety or energy inside 805 00:40:03,280 --> 00:40:06,560 Speaker 1: of it, how does that energy get out If nothing 806 00:40:06,600 --> 00:40:09,279 Speaker 1: can come out of a black hole? Right, and classically 807 00:40:09,320 --> 00:40:12,359 Speaker 1: according to general relativity, which is a classical theory, meaning 808 00:40:12,440 --> 00:40:16,040 Speaker 1: that ignores quantum mechanics. You're right, and classical black holes 809 00:40:16,160 --> 00:40:19,120 Speaker 1: do not emit anything. They're just one way doors of 810 00:40:19,200 --> 00:40:22,560 Speaker 1: information and objects. And so the way we usually talk 811 00:40:22,600 --> 00:40:25,200 Speaker 1: about black holes on this podcast is in the realm 812 00:40:25,200 --> 00:40:27,839 Speaker 1: of general relativity, because it's the only idea we have 813 00:40:28,200 --> 00:40:31,880 Speaker 1: to describe black holes. But we know that general relativity 814 00:40:32,000 --> 00:40:36,160 Speaker 1: isn't right because general relativity is not consistent with quantum mechanics, 815 00:40:36,160 --> 00:40:38,680 Speaker 1: which are pretty sure is the law of the universe. 816 00:40:38,840 --> 00:40:40,719 Speaker 1: And so what Hawking tried to do was like take 817 00:40:40,760 --> 00:40:44,320 Speaker 1: first steps towards a theory of quantum gravity, a quantum 818 00:40:44,360 --> 00:40:48,000 Speaker 1: mechanically consistent description of black holes. He wasn't able to 819 00:40:48,080 --> 00:40:50,240 Speaker 1: do that. We don't have a theory of quantum gravity. 820 00:40:50,360 --> 00:40:52,160 Speaker 1: What he did was sort of take general relativity and 821 00:40:52,200 --> 00:40:53,799 Speaker 1: try to tweak a little bit to make it a 822 00:40:53,920 --> 00:40:57,759 Speaker 1: little bit quantum mechanical. It's like semi classical now, and 823 00:40:57,800 --> 00:41:00,319 Speaker 1: so he's got sort of like a patched up version 824 00:41:00,320 --> 00:41:04,840 Speaker 1: of a theory of black holes that's not like general relativity, 825 00:41:05,080 --> 00:41:08,279 Speaker 1: but also not fully consistent with quantum mechanics. He still 826 00:41:08,360 --> 00:41:10,560 Speaker 1: has holes in his theory, that's what you're saying about 827 00:41:10,560 --> 00:41:13,480 Speaker 1: black holes. Yeah, and that's why, for example, we don't 828 00:41:13,520 --> 00:41:17,800 Speaker 1: have a good microscopic understanding of Hawking radiation. People talk about, 829 00:41:17,800 --> 00:41:20,480 Speaker 1: you know, virtual particles being produced at the edge of 830 00:41:20,480 --> 00:41:23,200 Speaker 1: a black hole, and there's some hand wavy stories which 831 00:41:23,200 --> 00:41:25,480 Speaker 1: we've given sometimes on this podcast, But the truth is 832 00:41:25,520 --> 00:41:28,040 Speaker 1: none of those are correct. They're sort of like hand 833 00:41:28,080 --> 00:41:30,120 Speaker 1: wavy stories that give you a sense for what might 834 00:41:30,160 --> 00:41:33,320 Speaker 1: be happening, but we don't have a good microscopic understanding 835 00:41:33,320 --> 00:41:36,160 Speaker 1: of what's going on because we don't understand the gravity 836 00:41:36,160 --> 00:41:39,080 Speaker 1: of quantum particles. So Hawking has sort of like a 837 00:41:39,120 --> 00:41:43,040 Speaker 1: statistical argument for why black holes should emit radiation, which 838 00:41:43,080 --> 00:41:46,280 Speaker 1: comes from them having temperature and therefore needing to radiate, 839 00:41:46,560 --> 00:41:49,040 Speaker 1: but it doesn't have like a good quantum description of 840 00:41:49,080 --> 00:41:51,960 Speaker 1: what's actually happened to these particles near the edge of 841 00:41:51,960 --> 00:41:53,680 Speaker 1: the black hole. We don't have that because we don't 842 00:41:53,719 --> 00:41:55,719 Speaker 1: have a theory of quantum gravity. He has sort of 843 00:41:55,760 --> 00:41:58,279 Speaker 1: like a band aid on top of general relativity that 844 00:41:58,360 --> 00:42:01,120 Speaker 1: lets him do a few character lations. But you know, 845 00:42:01,200 --> 00:42:03,359 Speaker 1: later people are going to realize that it's like an 846 00:42:03,360 --> 00:42:06,479 Speaker 1: approximation of the true theory. So he predicts that black 847 00:42:06,480 --> 00:42:09,080 Speaker 1: holes will glow in the dark, but we don't know 848 00:42:09,120 --> 00:42:11,160 Speaker 1: how they would fill in the dark. But have we 849 00:42:11,320 --> 00:42:13,400 Speaker 1: actually seen a black hole glow in the dark or 850 00:42:13,440 --> 00:42:16,640 Speaker 1: is this all still a prediction. We have not. Nobody's 851 00:42:16,680 --> 00:42:20,240 Speaker 1: ever observed hawking radiation. Remember, it would be really really faint. 852 00:42:20,520 --> 00:42:24,640 Speaker 1: Hawking radiation happens more dramatically for smaller black holes, so 853 00:42:24,719 --> 00:42:27,040 Speaker 1: for large black holes, like the few that we have seen, 854 00:42:27,480 --> 00:42:30,520 Speaker 1: it would be really really faint, and large black holes 855 00:42:30,560 --> 00:42:33,440 Speaker 1: tend to be surrounded by other things that glow very brightly, 856 00:42:33,640 --> 00:42:36,600 Speaker 1: like accretion disks a very very hot gas, so it 857 00:42:36,640 --> 00:42:39,680 Speaker 1: would be very difficult to observe hawking radiation. The best 858 00:42:39,680 --> 00:42:41,800 Speaker 1: way to do it would be to create a tiny 859 00:42:41,840 --> 00:42:44,439 Speaker 1: black hole, like a really small one that we could 860 00:42:44,480 --> 00:42:47,359 Speaker 1: study here in the laboratory before gob will up the earth, 861 00:42:47,520 --> 00:42:50,319 Speaker 1: because it would evaporate rather quickly and it would give 862 00:42:50,320 --> 00:42:52,400 Speaker 1: off a lot of Hawking radiation. So no, we have 863 00:42:52,480 --> 00:42:55,160 Speaker 1: never seen hawking radiation. So it's still just a theory, 864 00:42:55,239 --> 00:42:57,879 Speaker 1: but it's very convincing and it lets people do lots 865 00:42:57,880 --> 00:43:00,400 Speaker 1: of other calculations about black hole holes, and so the 866 00:43:00,640 --> 00:43:02,640 Speaker 1: whole theory built on top of it, all right. So 867 00:43:02,680 --> 00:43:05,439 Speaker 1: that's one way in which black holes can technically glow 868 00:43:05,520 --> 00:43:07,399 Speaker 1: in the dark. But they also sort of glow because 869 00:43:07,400 --> 00:43:09,280 Speaker 1: they have all this gas around them, right that it's 870 00:43:09,719 --> 00:43:11,759 Speaker 1: a lot of radiation, that's right, Yeah, And so that's 871 00:43:11,760 --> 00:43:14,040 Speaker 1: sort of like the black hole system. The black hole itself, 872 00:43:14,080 --> 00:43:16,879 Speaker 1: of course doesn't glow, but the stuff around it that's 873 00:43:16,920 --> 00:43:19,319 Speaker 1: getting like squeezed by all the energy from the black 874 00:43:19,320 --> 00:43:22,040 Speaker 1: hole does glow, all right. And so the other big 875 00:43:22,200 --> 00:43:26,200 Speaker 1: universe thing that glows is dark matter. Dark matter itself 876 00:43:26,239 --> 00:43:29,120 Speaker 1: also glows. You're saying, we don't know if dark matter glows. 877 00:43:29,120 --> 00:43:32,040 Speaker 1: It's really a fascinating question because we say that everything 878 00:43:32,040 --> 00:43:35,480 Speaker 1: in the universe that has the temperature glows, right, But 879 00:43:36,040 --> 00:43:38,480 Speaker 1: the caveat there is that it has to have some 880 00:43:38,520 --> 00:43:42,239 Speaker 1: sort of electromagnetic interaction. Like why do things glow, as 881 00:43:42,280 --> 00:43:44,400 Speaker 1: we were saying before, because the electrons inside them are 882 00:43:44,400 --> 00:43:46,920 Speaker 1: whizzing around and giving off photons. But if you're made 883 00:43:46,960 --> 00:43:49,640 Speaker 1: of things that don't interact with photons, like dark matter, 884 00:43:49,960 --> 00:43:52,719 Speaker 1: then you can't give off photons. So it might be 885 00:43:52,800 --> 00:43:55,200 Speaker 1: the dark matter has a temperature, like we know it 886 00:43:55,360 --> 00:43:58,120 Speaker 1: has a temperature, it moves it has a speed. But 887 00:43:58,200 --> 00:44:00,239 Speaker 1: it might be that it doesn't glow. It could the 888 00:44:00,320 --> 00:44:03,120 Speaker 1: only thing in the universe that has a temperature but 889 00:44:03,200 --> 00:44:07,120 Speaker 1: doesn't glowing, right, because it doesn't know how to talk 890 00:44:07,160 --> 00:44:10,160 Speaker 1: to the electromagnetic radiation. It doesn't interact with it or 891 00:44:10,520 --> 00:44:13,120 Speaker 1: know how to talk in that language or give it off, 892 00:44:13,160 --> 00:44:15,560 Speaker 1: and so it has all this energy, and so how 893 00:44:15,600 --> 00:44:17,920 Speaker 1: can it be glowing in a sort of energy sense. 894 00:44:18,080 --> 00:44:20,640 Speaker 1: It depends on how dark matter interacts. We know that 895 00:44:20,760 --> 00:44:23,840 Speaker 1: dark matter feels gravity, can talk to things via gravity. 896 00:44:24,080 --> 00:44:25,880 Speaker 1: It might be that it has some other force, like 897 00:44:25,920 --> 00:44:29,319 Speaker 1: there's some weird new dark electromagnetic force we had never 898 00:44:29,400 --> 00:44:32,960 Speaker 1: heard before, and maybe it can glow using dark photons, right, 899 00:44:32,960 --> 00:44:35,520 Speaker 1: But that's all speculations, so put that aside for now. 900 00:44:35,719 --> 00:44:37,880 Speaker 1: We do know that it feels gravity, and so it 901 00:44:38,000 --> 00:44:42,480 Speaker 1: might be that dark matter can glow gravitationally. Right. For example, 902 00:44:42,760 --> 00:44:45,799 Speaker 1: black holes that interact with each other and combine, they 903 00:44:45,840 --> 00:44:50,560 Speaker 1: give off gravitational radiation that's gravitational waves, and so dark 904 00:44:50,600 --> 00:44:52,880 Speaker 1: matter might be able to give off like very faint 905 00:44:53,000 --> 00:44:56,400 Speaker 1: gravitational waves as it's just sort of sitting around, slashing 906 00:44:56,440 --> 00:44:59,240 Speaker 1: around the universe. That's sort of like a faint glow, 907 00:44:59,440 --> 00:45:02,799 Speaker 1: not info tons in terms of other kinds of radiation. Right, 908 00:45:02,840 --> 00:45:06,240 Speaker 1: and interesting because I think we can detect gravitational waves, 909 00:45:06,400 --> 00:45:09,120 Speaker 1: but only from like these incredible events like two black 910 00:45:09,120 --> 00:45:13,040 Speaker 1: holes colliding, because that's how faint gravitational waves are. Are 911 00:45:13,040 --> 00:45:15,799 Speaker 1: you saying that dark matter might be giving off also 912 00:45:15,880 --> 00:45:19,839 Speaker 1: gravitational waves, but they would be so small and indetectable 913 00:45:19,880 --> 00:45:22,520 Speaker 1: that we would maybe never see them. You and I 914 00:45:22,560 --> 00:45:25,799 Speaker 1: are giving off gravitational waves. Anybody in the universe that 915 00:45:25,880 --> 00:45:29,440 Speaker 1: has mass and accelerates gives off gravitational waves. But as 916 00:45:29,440 --> 00:45:31,960 Speaker 1: you say, because gravity is so weak, that's undetectable. You 917 00:45:31,960 --> 00:45:35,880 Speaker 1: have to be an incredible mass undergoing incredible acceleration to 918 00:45:36,000 --> 00:45:38,640 Speaker 1: feel those gravitational waves. Wait, you and I are are 919 00:45:38,680 --> 00:45:42,319 Speaker 1: glowing in the gravitationals feel but only if we move 920 00:45:42,400 --> 00:45:44,560 Speaker 1: though if we stay still, we don't, Or do we 921 00:45:44,719 --> 00:45:47,200 Speaker 1: Or are you saying our atoms are emitting gravitational waves 922 00:45:47,239 --> 00:45:49,960 Speaker 1: all of those Yet if we accelerate in any way, 923 00:45:50,160 --> 00:45:52,440 Speaker 1: then we are giving off gravitational waves. So as we 924 00:45:52,480 --> 00:45:55,839 Speaker 1: move around the Sun, that's circular motion, that's acceleration. As 925 00:45:55,920 --> 00:45:57,960 Speaker 1: the Sun moves around the center of the galaxy, it's 926 00:45:58,000 --> 00:46:01,719 Speaker 1: glowing gravitationally. But these things are very faint, and even 927 00:46:01,719 --> 00:46:04,040 Speaker 1: the atoms in our body which do that, which accelerated 928 00:46:04,040 --> 00:46:07,239 Speaker 1: in any way, they give out gravitational radiation. We have 929 00:46:07,560 --> 00:46:11,160 Speaker 1: a podcast episode you might remember about the cosmic gravitational background. 930 00:46:11,480 --> 00:46:14,640 Speaker 1: That's like the sum of all these little gravitational waves 931 00:46:14,640 --> 00:46:17,320 Speaker 1: that you can't really discern because they're all so dim. 932 00:46:17,640 --> 00:46:19,759 Speaker 1: They just add up to like a general hum. But 933 00:46:19,840 --> 00:46:21,920 Speaker 1: I guess what you're saying is, like, you know, the 934 00:46:21,960 --> 00:46:24,400 Speaker 1: fact that we have a temperature means that our molecules 935 00:46:24,400 --> 00:46:29,480 Speaker 1: are vibrating. In that vibration, they are emitting gravitational waves. Yes, absolutely, 936 00:46:29,480 --> 00:46:34,280 Speaker 1: they are very very faint, probably never detectable, but technically, yes, whoa, 937 00:46:34,560 --> 00:46:38,359 Speaker 1: that's pretty cool. So we're all hot and glowy in 938 00:46:38,440 --> 00:46:40,960 Speaker 1: some sense exactly, and so even dark matter, which we 939 00:46:41,000 --> 00:46:44,640 Speaker 1: can see with photons, might be glowing gravitationally. And this 940 00:46:44,680 --> 00:46:47,480 Speaker 1: also gets into quantum mechanics, right, there's something called the 941 00:46:47,600 --> 00:46:51,279 Speaker 1: ultra violet catastrophe. Yes, the ultra violet catastrophe was one 942 00:46:51,280 --> 00:46:54,640 Speaker 1: of the first clues that told us about quantum mechanics. 943 00:46:55,000 --> 00:46:58,840 Speaker 1: When we people first calculated how black bodies might radiate 944 00:46:58,920 --> 00:47:03,239 Speaker 1: like at what equency should an object radiate given its temperature. 945 00:47:03,560 --> 00:47:07,000 Speaker 1: They did some basic calculations using electromagneticism, and they got 946 00:47:07,000 --> 00:47:10,200 Speaker 1: these crazy predictions. You know. They predicted, for example, that 947 00:47:10,280 --> 00:47:13,600 Speaker 1: an object at a thousand degrees kelvin should emit an 948 00:47:13,640 --> 00:47:16,719 Speaker 1: infinite amount of energy because there's an infinite number of 949 00:47:16,760 --> 00:47:19,399 Speaker 1: ways for a photon to glow. There's an infinite number 950 00:47:19,400 --> 00:47:22,480 Speaker 1: of like different wavelengths of photon could have. They fought, 951 00:47:22,760 --> 00:47:25,280 Speaker 1: and so they got all these crazy numbers, which obviously 952 00:47:25,400 --> 00:47:27,879 Speaker 1: didn't agree with their experiments. You know, you put something 953 00:47:27,880 --> 00:47:32,040 Speaker 1: in the toaster, it doesn't like explode with infinite energy, right, 954 00:47:32,280 --> 00:47:35,080 Speaker 1: the Sun is not exploding with infinite energy. It depends 955 00:47:35,120 --> 00:47:38,399 Speaker 1: on what you put into that the toaster oven. Put 956 00:47:38,400 --> 00:47:40,640 Speaker 1: in too much Halloween candy and pop rocks, it might 957 00:47:40,719 --> 00:47:43,520 Speaker 1: explode with energy. Yeah, some mento, some coke, who knows. 958 00:47:43,600 --> 00:47:46,200 Speaker 1: But this was known as the ultra violet catastrophe like 959 00:47:46,239 --> 00:47:49,160 Speaker 1: a twenty years ago because people didn't understand why this 960 00:47:49,239 --> 00:47:52,760 Speaker 1: wasn't happening. The calculations suggested it should. Obviously it wasn't, 961 00:47:52,920 --> 00:47:55,680 Speaker 1: And it wasn't until a young physicist named Max Plunk 962 00:47:56,040 --> 00:47:59,920 Speaker 1: realized that if you made this weird assumption that photons 963 00:48:00,000 --> 00:48:03,160 Speaker 1: couldn't have just any arbitrary energy, but that they came 964 00:48:03,200 --> 00:48:05,760 Speaker 1: in steps, that they were like quantized units of energy. 965 00:48:06,040 --> 00:48:08,160 Speaker 1: Then that killed the problem because it meant that there 966 00:48:08,160 --> 00:48:11,200 Speaker 1: weren't an infinite number of modes for photons to have. 967 00:48:11,320 --> 00:48:13,759 Speaker 1: They're just a finite ladder. And the way the math 968 00:48:13,800 --> 00:48:15,960 Speaker 1: worked out, that meant that it solved the problem and 969 00:48:15,960 --> 00:48:19,680 Speaker 1: it predicted perfectly the experiments, and so Plank was like, oh, well, 970 00:48:19,880 --> 00:48:23,480 Speaker 1: maybe things are quantized. Interesting. So actually quantum mechanics sort 971 00:48:23,480 --> 00:48:26,319 Speaker 1: of limits how things glow in the dark, like things 972 00:48:26,360 --> 00:48:28,040 Speaker 1: would glow in the dark more if it wasn't for 973 00:48:28,120 --> 00:48:31,080 Speaker 1: quantum mechanics. Yes, exactly, quantum mechanics limits how things glow. 974 00:48:31,280 --> 00:48:33,279 Speaker 1: And things glowing in the dark was one of our 975 00:48:33,400 --> 00:48:36,880 Speaker 1: very first clues that the universe is quantum mechanical. And 976 00:48:36,920 --> 00:48:39,680 Speaker 1: it was Einstein actually who recognized this. Plank just said like, 977 00:48:39,880 --> 00:48:41,759 Speaker 1: I don't know what this means, but if you make 978 00:48:41,800 --> 00:48:45,000 Speaker 1: this assumption, the math all works out, and Einstein is thinking, 979 00:48:45,440 --> 00:48:47,799 Speaker 1: and he read about the photo electric effect. Check out 980 00:48:47,800 --> 00:48:50,319 Speaker 1: a whole podcast about the discovery the photon. It was 981 00:48:50,360 --> 00:48:52,800 Speaker 1: Einstein who put it all together and said, oh, maybe 982 00:48:52,840 --> 00:48:56,120 Speaker 1: photons travel in chunks that they are quantized in units. 983 00:48:56,280 --> 00:48:58,080 Speaker 1: I guess it's all that. This ties it all back. 984 00:48:58,360 --> 00:49:00,640 Speaker 1: Things glow in the dark at the end of the day. 985 00:49:00,680 --> 00:49:04,000 Speaker 1: It is a very fundamental and quantum mechanical process. Yeah, 986 00:49:04,080 --> 00:49:06,920 Speaker 1: And asking questions about why things glow and why they 987 00:49:06,960 --> 00:49:08,920 Speaker 1: don't glow and why they don't explode when you put 988 00:49:08,920 --> 00:49:12,480 Speaker 1: them in toaster can sometimes reveal crazy secrets about the 989 00:49:12,560 --> 00:49:15,760 Speaker 1: nature of the universe, like quantum mechanics, and so asking 990 00:49:15,840 --> 00:49:18,800 Speaker 1: questions about like dark matter glowing and black holes glowing 991 00:49:18,920 --> 00:49:21,239 Speaker 1: might help us in our struggles to understand the big 992 00:49:21,320 --> 00:49:24,040 Speaker 1: questions of today's physics. What's the universe made out of? 993 00:49:24,080 --> 00:49:27,759 Speaker 1: And what is the quantum mechanical description of space and time? Yeah, 994 00:49:27,800 --> 00:49:29,480 Speaker 1: and so I guess it reminds you a little bit 995 00:49:29,480 --> 00:49:32,319 Speaker 1: that the universe is kind of speaking to us all 996 00:49:32,360 --> 00:49:34,360 Speaker 1: the time, even in the dark. You know, even in 997 00:49:34,400 --> 00:49:38,400 Speaker 1: the dark. You know, animals and bacteria and and creatures glow, 998 00:49:38,640 --> 00:49:41,520 Speaker 1: and you can mix chemicals to glow as well. And 999 00:49:42,000 --> 00:49:44,000 Speaker 1: things that they're in space are glowing all the time. 1000 00:49:44,040 --> 00:49:47,680 Speaker 1: And even yourself within you are glowing, that's right, And 1001 00:49:47,960 --> 00:49:50,000 Speaker 1: all those stars out there in the universe that are 1002 00:49:50,040 --> 00:49:52,879 Speaker 1: sending you photons, They're telling you about themselves. They're telling 1003 00:49:52,880 --> 00:49:55,239 Speaker 1: you stories about what they are burning and what they 1004 00:49:55,239 --> 00:49:58,640 Speaker 1: are made out of. The University is like screaming information 1005 00:49:58,640 --> 00:50:00,319 Speaker 1: at us. And to me, the frustrating thing is that 1006 00:50:00,360 --> 00:50:03,160 Speaker 1: most of the time we aren't listening. Yeah, except they're saying, 1007 00:50:03,400 --> 00:50:07,839 Speaker 1: eat more candy, eat more candy. So maybe it's good 1008 00:50:07,840 --> 00:50:10,440 Speaker 1: that we don't listen to them all the time. I 1009 00:50:10,440 --> 00:50:12,120 Speaker 1: think you should give your kids an extra piece of 1010 00:50:12,120 --> 00:50:14,600 Speaker 1: candy for this podcast. Oh yeah, I'm sure they sneak 1011 00:50:14,680 --> 00:50:17,560 Speaker 1: some anyways. All right, Well, we hope you enjoyed that, 1012 00:50:17,719 --> 00:50:20,959 Speaker 1: and maybe this Halloween or in general, look at things 1013 00:50:20,960 --> 00:50:23,600 Speaker 1: in the dark a little bit differently because everything is 1014 00:50:23,960 --> 00:50:27,320 Speaker 1: glowing in the dark and trying to tell you answers 1015 00:50:27,400 --> 00:50:30,040 Speaker 1: to the secrets of the universe. Thanks for joining us, 1016 00:50:30,320 --> 00:50:40,400 Speaker 1: See you next time. Thanks for listening, and remember that 1017 00:50:40,520 --> 00:50:43,279 Speaker 1: Daniel and Jorge Explain the Universe is a production of 1018 00:50:43,400 --> 00:50:46,760 Speaker 1: I Heart Radio or more podcast for my Heart Radio, 1019 00:50:46,880 --> 00:50:50,480 Speaker 1: visit the I Heart Radio app, Apple Podcasts, or wherever 1020 00:50:50,600 --> 00:51:01,200 Speaker 1: you listen to your favorite shows.