1 00:00:08,600 --> 00:00:10,720 Speaker 1: Hey, Daniel, how do you like your coffee? Oh? I 2 00:00:10,800 --> 00:00:15,000 Speaker 1: like it very dark, basically black. What about your chocolate? 3 00:00:15,440 --> 00:00:20,320 Speaker 1: Also pretty dark? Maybe? Like? What about your wine? How 4 00:00:20,360 --> 00:00:22,640 Speaker 1: do you drink your wine? Well? I like a pretty 5 00:00:22,720 --> 00:00:25,959 Speaker 1: dark cabernet. Actually, now, are you optimistic about the fate 6 00:00:26,000 --> 00:00:28,480 Speaker 1: of humanity? You know, I'll be honest until we start 7 00:00:28,520 --> 00:00:31,480 Speaker 1: dismantling more nuclear weapons. I have a pretty dark view 8 00:00:31,520 --> 00:00:36,120 Speaker 1: of our future. You kind of a dark physicist. Maybe 9 00:00:36,120 --> 00:00:38,760 Speaker 1: you should lighten up a little, you know, try some dessert, wine, 10 00:00:38,800 --> 00:00:42,440 Speaker 1: some rose, maybe maybe even some white chocolate. No, no, no, man, 11 00:00:42,520 --> 00:00:45,760 Speaker 1: we live in a dark universe where dominated by dark matter, 12 00:00:45,920 --> 00:00:49,800 Speaker 1: dark energy, and dark chocolate. You know what Yoda says, 13 00:00:50,200 --> 00:00:53,599 Speaker 1: once you go into the dark side, forever your destiny 14 00:00:54,040 --> 00:00:59,160 Speaker 1: well dominate. Do you think Yoda like dark chocolate? I 15 00:00:59,200 --> 00:01:18,120 Speaker 1: always knew you were a dark fisicist. Daniel. Hi am 16 00:01:18,120 --> 00:01:21,120 Speaker 1: poor handmade cartoonists and the creator of PhD comics. Hi, 17 00:01:21,280 --> 00:01:24,840 Speaker 1: I'm Daniel. I'm a particle physicist and a professor UC Irvine. 18 00:01:25,000 --> 00:01:28,160 Speaker 1: And white chocolate is not chocolate. It is chocolate. Then 19 00:01:28,200 --> 00:01:31,320 Speaker 1: it's made from chocolate, made from chocolate, not the same 20 00:01:31,360 --> 00:01:35,800 Speaker 1: as chocolate. You just don't like it. You still want 21 00:01:35,800 --> 00:01:38,680 Speaker 1: to categorize this chocolate, But scientifically, I think if you 22 00:01:38,800 --> 00:01:41,399 Speaker 1: asked a you know, chemist, they would say it's a 23 00:01:41,480 --> 00:01:43,880 Speaker 1: it's chocolate. I don't know. I think it doesn't have 24 00:01:43,920 --> 00:01:47,160 Speaker 1: any cocoa in it. It can't be chocolate. Doesn't taste 25 00:01:47,200 --> 00:01:49,680 Speaker 1: like chocolate. You know, white chocolate is chocolate the same 26 00:01:49,720 --> 00:01:52,200 Speaker 1: way deep dish pizza is pizza. But you do know 27 00:01:52,240 --> 00:01:54,320 Speaker 1: it's made from chocolate, right, Like I think it uses 28 00:01:54,360 --> 00:01:57,560 Speaker 1: like the cocoa butter from chocolate beans. Yeah, it's sort 29 00:01:57,560 --> 00:02:00,280 Speaker 1: of like hangs around when chocolate is made, sort calls 30 00:02:00,320 --> 00:02:05,480 Speaker 1: itself chocolate nearby it's chocolate and I'll give it that much. 31 00:02:05,600 --> 00:02:07,640 Speaker 1: Oh man, how can it be a jacent if it 32 00:02:07,680 --> 00:02:10,040 Speaker 1: comes from chocolated Daniel, I think you're stretching things a 33 00:02:10,080 --> 00:02:13,200 Speaker 1: little bit here. My kids are coming from chocolate, but 34 00:02:13,240 --> 00:02:16,720 Speaker 1: they're not chocolate, right. You should be more candy inclusive, Tenny, 35 00:02:17,960 --> 00:02:20,440 Speaker 1: white chocolate is delicious. It's just not chocolate. But welcome 36 00:02:20,440 --> 00:02:23,239 Speaker 1: to our podcast. Daniel and jorhead the Bait Chocolate apparently 37 00:02:23,360 --> 00:02:26,240 Speaker 1: for an hour instead of talking about physics and explain 38 00:02:26,320 --> 00:02:29,320 Speaker 1: the universe, in which we explore all the questions out there, 39 00:02:29,360 --> 00:02:32,160 Speaker 1: the dark ones, the white ones, the milky ones, all 40 00:02:32,200 --> 00:02:34,840 Speaker 1: the questions of the universe that are rattling around in 41 00:02:34,960 --> 00:02:38,880 Speaker 1: your brain and in hours, the questions that make us human, 42 00:02:38,960 --> 00:02:41,960 Speaker 1: the questions that make us wonder why the universe is 43 00:02:42,040 --> 00:02:44,240 Speaker 1: this way and not some other way? Could it have 44 00:02:44,320 --> 00:02:46,200 Speaker 1: been this way? Did it have to turn out in 45 00:02:46,200 --> 00:02:49,240 Speaker 1: this particular manner? What are the rules of this universe? 46 00:02:49,280 --> 00:02:51,760 Speaker 1: And is it possible for them to make sense to us? 47 00:02:51,840 --> 00:02:54,160 Speaker 1: And is it possible for Daniel and Jorge to explain 48 00:02:54,200 --> 00:02:57,800 Speaker 1: them to you in less than an hour while eating chocolates? Apparently, 49 00:02:57,919 --> 00:03:00,600 Speaker 1: but only dark or milk? What about chocolate? Are you 50 00:03:00,639 --> 00:03:03,160 Speaker 1: a fan of milk chocolate? Milk chocolate is chocolate. But 51 00:03:03,320 --> 00:03:07,359 Speaker 1: I'm not a fan, I see, And there are different 52 00:03:07,360 --> 00:03:09,840 Speaker 1: categories here of exclusion for you. Oh yeah, I got 53 00:03:09,880 --> 00:03:12,160 Speaker 1: a whole matrix going here. But it is an amazing 54 00:03:12,160 --> 00:03:15,480 Speaker 1: and beautiful and sometimes even delicious universe, full of amazing 55 00:03:15,520 --> 00:03:19,359 Speaker 1: mysteries and tantalizing questions to answer and discover out there, 56 00:03:19,480 --> 00:03:21,720 Speaker 1: and fortunately humans are here for all of it, to 57 00:03:21,760 --> 00:03:25,320 Speaker 1: answer these questions and to wonder about the amazing things 58 00:03:25,400 --> 00:03:27,200 Speaker 1: that are out there. That's right, and one of the 59 00:03:27,200 --> 00:03:30,240 Speaker 1: most basic questions we ask about the universe is just 60 00:03:30,600 --> 00:03:33,760 Speaker 1: what's in it? What's out there in the universe sharing 61 00:03:33,840 --> 00:03:36,200 Speaker 1: this cosmos with us. There's this sense that if you 62 00:03:36,200 --> 00:03:38,880 Speaker 1: could like make an accounting of all the stuff, all 63 00:03:38,960 --> 00:03:41,040 Speaker 1: the forces in the matter, and all the particles in 64 00:03:41,040 --> 00:03:44,560 Speaker 1: the universe, you'd get a sense for why the universe 65 00:03:44,760 --> 00:03:47,480 Speaker 1: is the way that it is the way. For example, 66 00:03:47,480 --> 00:03:49,640 Speaker 1: if you'd like looked at the ingredients of a pizza, 67 00:03:49,880 --> 00:03:51,480 Speaker 1: you can get a sense for, like what makes a 68 00:03:51,520 --> 00:03:54,440 Speaker 1: pizza a pizza. Yeah, because for thousands of years, we 69 00:03:54,480 --> 00:03:56,640 Speaker 1: thought that, you know, the stuff that we were made 70 00:03:56,640 --> 00:03:59,360 Speaker 1: out of was all there was too stuff, you know, 71 00:03:59,440 --> 00:04:02,360 Speaker 1: the electron and corks and protons and neutrons that we're 72 00:04:02,400 --> 00:04:04,000 Speaker 1: made out of. We thought that was the whole thing 73 00:04:04,080 --> 00:04:06,400 Speaker 1: that was in the universe. But actually it turns out 74 00:04:06,400 --> 00:04:09,280 Speaker 1: that most of the universe is made out of something else, 75 00:04:09,600 --> 00:04:13,200 Speaker 1: something dark and mysterious. Yes, And the history of physics 76 00:04:13,320 --> 00:04:16,200 Speaker 1: is these waves of realization, discovering that we are not 77 00:04:16,320 --> 00:04:18,320 Speaker 1: at the center of the universe, we are not at 78 00:04:18,360 --> 00:04:20,400 Speaker 1: the center of the Solar system, we are not really 79 00:04:20,400 --> 00:04:22,960 Speaker 1: at the center of anything, and then discovering that our 80 00:04:23,080 --> 00:04:25,599 Speaker 1: kind of matter is not even that special that we 81 00:04:25,680 --> 00:04:29,840 Speaker 1: make up a tiny little fraction of this incredible universe pizza. 82 00:04:29,880 --> 00:04:32,880 Speaker 1: Oh boy, Daniel, are you saying we are universe at Jason. 83 00:04:32,960 --> 00:04:34,680 Speaker 1: We're not really part of the universe. We're not really 84 00:04:34,839 --> 00:04:39,320 Speaker 1: universe material. We're sort of dark matter adjacent, right, We're 85 00:04:39,360 --> 00:04:42,760 Speaker 1: around when the dark matter formed all this structure. We 86 00:04:42,880 --> 00:04:45,680 Speaker 1: sort of like we're followers, but we're not dark matter. Yeah. 87 00:04:46,160 --> 00:04:48,400 Speaker 1: Do you think there's some snob courmet I don't know, 88 00:04:48,640 --> 00:04:52,080 Speaker 1: universe eater out there judging us talking down about the 89 00:04:52,160 --> 00:04:55,680 Speaker 1: humanity and all the stars and planets and galaxies in 90 00:04:55,720 --> 00:04:58,640 Speaker 1: the universe, saying that's not really universe. Yeah, I hope. So, 91 00:04:58,680 --> 00:05:00,440 Speaker 1: I hope that there are some dark a adans out 92 00:05:00,440 --> 00:05:03,599 Speaker 1: there made of dark matter, with their incredibly dark dark 93 00:05:03,680 --> 00:05:05,719 Speaker 1: chocolate made of dark matter, and they're looking at our 94 00:05:05,800 --> 00:05:09,880 Speaker 1: dark chocolate. They're like, that's ridiculous. Well, I guess the 95 00:05:09,880 --> 00:05:12,000 Speaker 1: good news is they they're not gonna eat us, because 96 00:05:12,000 --> 00:05:16,040 Speaker 1: if they're there's nobby about it, like you are white chocolate. 97 00:05:16,160 --> 00:05:18,279 Speaker 1: That's good news for the white chocolate. Yeah. Here ago 98 00:05:18,400 --> 00:05:21,279 Speaker 1: you can turn anything into positive news. I appreciate that. Yeah, 99 00:05:21,279 --> 00:05:23,080 Speaker 1: but there is a lot of dark matter in the universe. 100 00:05:23,120 --> 00:05:25,120 Speaker 1: In fact, it's most of the stuff in the universe 101 00:05:25,360 --> 00:05:27,760 Speaker 1: is dark matter. Of the stuff in the universe. I mean, 102 00:05:27,839 --> 00:05:30,240 Speaker 1: that's right. Even though we can't see it directly, we 103 00:05:30,279 --> 00:05:32,560 Speaker 1: can tell that dark matter is there, that it's a 104 00:05:32,640 --> 00:05:35,480 Speaker 1: thing that is affecting the whole shape of the universe. 105 00:05:35,520 --> 00:05:38,400 Speaker 1: It affected their universe early on and its little wiggles 106 00:05:38,400 --> 00:05:41,600 Speaker 1: and jiggles. It affected the formation of structure in the universe. 107 00:05:41,640 --> 00:05:44,920 Speaker 1: It even shapes how galaxies spin today. So we know 108 00:05:45,040 --> 00:05:46,880 Speaker 1: that it's there, we know that it's out there, and 109 00:05:46,920 --> 00:05:49,360 Speaker 1: we know that it dominates the universe in terms of 110 00:05:49,400 --> 00:05:52,520 Speaker 1: like the budget of the universe is mostly dark matter, 111 00:05:52,839 --> 00:05:56,240 Speaker 1: not what we used to call normal matter. I e us. Yeah, 112 00:05:56,240 --> 00:05:58,920 Speaker 1: it's something like, what's the exact budget percentage of dark 113 00:05:58,920 --> 00:06:00,920 Speaker 1: matter in the universe compared to the regular stuff we're 114 00:06:00,920 --> 00:06:03,640 Speaker 1: made out of. It's about five to one dark matter 115 00:06:03,720 --> 00:06:06,080 Speaker 1: to normal matter, all right, So then that's like eight 116 00:06:06,200 --> 00:06:09,120 Speaker 1: percent of the universe is sort of dark matter. Yeah, 117 00:06:09,160 --> 00:06:12,000 Speaker 1: eighty percent of the universe. So you could almost neglect 118 00:06:12,279 --> 00:06:13,920 Speaker 1: our part of the universe and you still got to 119 00:06:14,040 --> 00:06:20,799 Speaker 1: be on your exam Befo, bueno, that's right, bueno. Barry 120 00:06:20,880 --> 00:06:23,279 Speaker 1: on is exactly. Yeah, you could ignore all the atoms 121 00:06:23,279 --> 00:06:25,880 Speaker 1: in the universe and that would only be five percent 122 00:06:26,000 --> 00:06:28,520 Speaker 1: of the energy in the universe or twenty percent of 123 00:06:28,560 --> 00:06:30,840 Speaker 1: the matter in the universe. So in some sense, the 124 00:06:30,920 --> 00:06:33,800 Speaker 1: question what is the universe made out of? What is 125 00:06:33,839 --> 00:06:36,800 Speaker 1: all this crazy stuff? Tells you that what we're made 126 00:06:36,800 --> 00:06:38,279 Speaker 1: out of is not a big part of it is 127 00:06:38,320 --> 00:06:41,839 Speaker 1: not a central element in the structure of the universe. Right, 128 00:06:41,920 --> 00:06:44,920 Speaker 1: And just to clarify, most of this stuff and energy 129 00:06:44,920 --> 00:06:48,040 Speaker 1: in the universe is dark energy, which is something totally different. 130 00:06:48,240 --> 00:06:50,520 Speaker 1: But if we're just talking about stuff like matter, things 131 00:06:50,520 --> 00:06:53,880 Speaker 1: that feel gravity, then most of it is dark matter. 132 00:06:54,080 --> 00:06:56,840 Speaker 1: That's right. The matter portion of the universe is about 133 00:06:57,640 --> 00:07:02,719 Speaker 1: and of that thirty percent, eight percent that is dark matter. 134 00:07:03,080 --> 00:07:06,039 Speaker 1: So if the matter portion of the universe it is 135 00:07:06,120 --> 00:07:08,560 Speaker 1: dark matter, well that's pretty amazing. It's almost like most 136 00:07:08,600 --> 00:07:10,520 Speaker 1: of the stuff in the universe is this other stuff 137 00:07:10,640 --> 00:07:13,600 Speaker 1: called dark matter, but we don't know actually what it is, right, 138 00:07:13,600 --> 00:07:16,120 Speaker 1: It's pretty mysterious. We've only know it's there, we haven't 139 00:07:16,160 --> 00:07:19,320 Speaker 1: actually seen it directly because it's dark. Yeah, but it's 140 00:07:19,320 --> 00:07:22,280 Speaker 1: a great story. You know. I got into physics for 141 00:07:22,360 --> 00:07:26,160 Speaker 1: exactly these kinds of realizations, discovering that the universe out 142 00:07:26,160 --> 00:07:28,040 Speaker 1: there is not the one that you thought it was, 143 00:07:28,160 --> 00:07:31,160 Speaker 1: or that scientists and deep thinkers for thousands of years 144 00:07:31,360 --> 00:07:34,400 Speaker 1: hadn't known the true picture of the universe. You know. 145 00:07:34,480 --> 00:07:38,080 Speaker 1: Physics is this incredible technique to like reveal the truth 146 00:07:38,200 --> 00:07:42,240 Speaker 1: about the universe, to methodically build up knowledge and tell 147 00:07:42,320 --> 00:07:44,920 Speaker 1: us what's actually out there. So for it to discover 148 00:07:45,080 --> 00:07:48,440 Speaker 1: something shocking, like an enormous plot twist, like wow, it 149 00:07:48,560 --> 00:07:50,560 Speaker 1: turns out most of the stuff in the universe out 150 00:07:50,560 --> 00:07:52,960 Speaker 1: there is something you never heard about or thought about 151 00:07:53,040 --> 00:07:56,320 Speaker 1: or felt before. That's fantastic and it's exactly the kind 152 00:07:56,360 --> 00:07:58,720 Speaker 1: of thing that I hope happens, you know, again and again, 153 00:07:58,880 --> 00:08:01,680 Speaker 1: overturning everything we thought we knew about the universe. Yeah, 154 00:08:01,760 --> 00:08:04,440 Speaker 1: we know you went into physics for dark reasons. Daniels 155 00:08:06,640 --> 00:08:09,160 Speaker 1: that it's pretty close to home, given that a group 156 00:08:09,160 --> 00:08:11,680 Speaker 1: in Los Almos where they invented nuclear weapons which are 157 00:08:11,680 --> 00:08:15,880 Speaker 1: now being used to threaten genocide against civilian populations. So yeah, 158 00:08:15,880 --> 00:08:17,840 Speaker 1: that one stings a little bit, but it might say 159 00:08:17,960 --> 00:08:20,560 Speaker 1: humanity even if the media ever comes towards Earth and 160 00:08:20,680 --> 00:08:23,000 Speaker 1: we you know, break it up with nuclear weapons, then 161 00:08:23,040 --> 00:08:25,880 Speaker 1: then your parents would be heroes. There you go. All right, 162 00:08:25,960 --> 00:08:28,800 Speaker 1: So in some scenario we are saving the Earth instead 163 00:08:28,800 --> 00:08:31,400 Speaker 1: of destroying it. You know, you apply the quantum physics principle. 164 00:08:31,520 --> 00:08:35,079 Speaker 1: You know, it's all true. It's just the different probabilities. 165 00:08:35,160 --> 00:08:38,680 Speaker 1: There's a little white chocolate lining to that dark chocolate cloud. 166 00:08:38,960 --> 00:08:42,720 Speaker 1: Oh no, that ruins it for you though. It doesn't 167 00:08:42,720 --> 00:08:44,960 Speaker 1: taste as good, but it goes down easier. Yeah. Yeah, 168 00:08:44,960 --> 00:08:46,719 Speaker 1: So most of the stuff in the universe is made 169 00:08:46,720 --> 00:08:48,400 Speaker 1: out of dark matter, and so it kind of makes 170 00:08:48,400 --> 00:08:51,680 Speaker 1: you wonder if that's all that's dark in the universe. 171 00:08:51,720 --> 00:08:54,280 Speaker 1: Could there be other things in the universe that we're 172 00:08:54,320 --> 00:08:57,160 Speaker 1: not seeing or that we can't see. And it's certainly 173 00:08:57,200 --> 00:08:59,800 Speaker 1: true that most of the universe are things that you 174 00:09:00,080 --> 00:09:02,680 Speaker 1: cannot see directly. If you look out in front of you, 175 00:09:02,880 --> 00:09:05,359 Speaker 1: the information that's coming to you is just from photons, 176 00:09:05,360 --> 00:09:09,000 Speaker 1: and photons can only interact with things that have electric charges. 177 00:09:09,400 --> 00:09:12,360 Speaker 1: For example, there are particles flying right in front of 178 00:09:12,360 --> 00:09:15,760 Speaker 1: you right now that you cannot see. Billions of neutrinos 179 00:09:15,800 --> 00:09:19,280 Speaker 1: coming from the Sun raining down constantly in every square 180 00:09:19,320 --> 00:09:22,120 Speaker 1: centimeter per second, but they are invisible to you. So 181 00:09:22,160 --> 00:09:25,800 Speaker 1: the true universe out there. The actual reality of the 182 00:09:25,920 --> 00:09:29,400 Speaker 1: universe outside your skull is vastly different from the tiny 183 00:09:29,520 --> 00:09:31,840 Speaker 1: slice of it that you can see. Yeah, because if 184 00:09:31,840 --> 00:09:34,920 Speaker 1: we can't see of the stuff in the universe, it 185 00:09:35,080 --> 00:09:37,280 Speaker 1: kind of makes me wonder what else it's doing or 186 00:09:37,320 --> 00:09:40,640 Speaker 1: what else it can do, like is it maybe radiating 187 00:09:40,880 --> 00:09:44,840 Speaker 1: dark forces or dark light? Exactly? Because our kind of 188 00:09:44,880 --> 00:09:47,560 Speaker 1: matter does all sorts of complicated things. It doesn't just 189 00:09:47,760 --> 00:09:50,360 Speaker 1: sit there right. It shoots off photons at each other. 190 00:09:50,360 --> 00:09:53,440 Speaker 1: It has electromagnetic forces and strong forces and weak forces, 191 00:09:53,440 --> 00:09:56,680 Speaker 1: and forms complicated things like ice cream and pizza and chocolate, 192 00:09:56,720 --> 00:09:58,960 Speaker 1: and so a natural question is what's going on with 193 00:09:59,000 --> 00:10:01,920 Speaker 1: the dark matter? What else can it do? Can it 194 00:10:02,040 --> 00:10:05,160 Speaker 1: interact with itself in some way? So today on the podcast, 195 00:10:05,160 --> 00:10:14,320 Speaker 1: we'll be asking the question what is dark radiation? Now, Daniel, 196 00:10:14,320 --> 00:10:16,440 Speaker 1: this sort of sounds like an oxy moron, you know, 197 00:10:16,440 --> 00:10:19,800 Speaker 1: you're almost asking like, what is not light light? Exactly? 198 00:10:19,840 --> 00:10:21,280 Speaker 1: But this is the kind of game we play in 199 00:10:21,280 --> 00:10:23,560 Speaker 1: physics all the time. We don't really know how to 200 00:10:23,559 --> 00:10:26,319 Speaker 1: grapple with the unknown, so we tend to explore it 201 00:10:26,400 --> 00:10:30,240 Speaker 1: in terms of the known. Like when we think about photons, 202 00:10:30,440 --> 00:10:32,600 Speaker 1: we don't really know how to deal with the quantum objects. 203 00:10:32,600 --> 00:10:34,400 Speaker 1: We say, is it a particle? Is it a wave? 204 00:10:34,440 --> 00:10:36,679 Speaker 1: It's kind of both. That's kind of the same. It's 205 00:10:36,679 --> 00:10:39,320 Speaker 1: a contradiction there, right, and so here that's what we're doing. 206 00:10:39,320 --> 00:10:41,800 Speaker 1: We're saying, well, we know about photons, is there like 207 00:10:41,960 --> 00:10:45,800 Speaker 1: another kind of like dark matter version of the photon. 208 00:10:46,040 --> 00:10:50,280 Speaker 1: Were extrapolating from what we know into what we don't know. Interesting, well, 209 00:10:50,320 --> 00:10:52,960 Speaker 1: it sounds like the plot device for a great science 210 00:10:52,960 --> 00:10:55,800 Speaker 1: fic to novel or the next Marvel movie. You know, 211 00:10:56,000 --> 00:10:59,199 Speaker 1: dark radiation. That's how you know Stephen Strange gets his 212 00:10:59,280 --> 00:11:01,320 Speaker 1: powers or something. That's right. And if they are like 213 00:11:01,360 --> 00:11:05,160 Speaker 1: what ten avengers made of normal matter, there should be like, 214 00:11:05,240 --> 00:11:08,679 Speaker 1: you know, forty avengers made of dark matter, the dark avengers, 215 00:11:09,200 --> 00:11:13,520 Speaker 1: Oh many, they can make another gazillion dark billions of dollars. 216 00:11:13,679 --> 00:11:15,480 Speaker 1: That's right, and my one percent cut of that is 217 00:11:15,480 --> 00:11:19,400 Speaker 1: going to be pretty sweet. Hopefully not you don't like 218 00:11:19,440 --> 00:11:22,959 Speaker 1: sweet things exactly, it'll be pretty dark. Pile up those 219 00:11:23,040 --> 00:11:25,439 Speaker 1: dark dollars in my dark bank account. Only pay Daniel 220 00:11:25,440 --> 00:11:29,400 Speaker 1: with bitter dollars. We should start some sort of dark 221 00:11:29,480 --> 00:11:35,480 Speaker 1: matter currency, that's right, dark chocolate coin. But it is 222 00:11:35,520 --> 00:11:38,360 Speaker 1: a real question in physics, what is going on with 223 00:11:38,400 --> 00:11:41,600 Speaker 1: the dark matter? Is it interacting with itself? Are dark 224 00:11:41,840 --> 00:11:45,960 Speaker 1: matter particles shooting dark photons at each other? We just 225 00:11:46,000 --> 00:11:49,199 Speaker 1: don't know. It is a dark question. And so as usual, 226 00:11:49,240 --> 00:11:51,160 Speaker 1: we were wondering how many people out there had thought 227 00:11:51,200 --> 00:11:55,160 Speaker 1: about this question or even know what these two words 228 00:11:55,200 --> 00:11:57,559 Speaker 1: put together could mean. So, as usual, Daniel went out 229 00:11:57,559 --> 00:12:01,559 Speaker 1: there into the Internet to ask people what is dark radiation? 230 00:12:01,720 --> 00:12:04,040 Speaker 1: And I'm very grateful to those of you who volunteered 231 00:12:04,040 --> 00:12:06,800 Speaker 1: to try to answer this question without having the opportunity 232 00:12:06,840 --> 00:12:09,160 Speaker 1: to look it up or Google or get a PhD 233 00:12:09,200 --> 00:12:11,640 Speaker 1: in physics first, And so thank you to all of 234 00:12:11,640 --> 00:12:13,680 Speaker 1: those of you who volunteered. And if you would like 235 00:12:13,760 --> 00:12:17,360 Speaker 1: to hear your voice speculating baselessly on the podcast, please 236 00:12:17,400 --> 00:12:20,200 Speaker 1: don't be shy right to me. Two questions at Daniel 237 00:12:20,240 --> 00:12:23,400 Speaker 1: and Jorge dot com. Has anyone tried that? They're like, oh, 238 00:12:23,520 --> 00:12:25,640 Speaker 1: that's a great question, give me a seven years, I'll 239 00:12:25,679 --> 00:12:27,360 Speaker 1: come back with a PhD and answer. Or is that 240 00:12:27,400 --> 00:12:29,880 Speaker 1: what you do to your grad students every day? Yeah? 241 00:12:29,920 --> 00:12:31,520 Speaker 1: I take the answers people give me. I'm like, oh, 242 00:12:31,559 --> 00:12:33,200 Speaker 1: that's a good idea for a project, and then I 243 00:12:33,200 --> 00:12:36,360 Speaker 1: go write a grand proposal based on it nice, and 244 00:12:36,360 --> 00:12:39,240 Speaker 1: then you get dark bitter money for it, and my 245 00:12:39,280 --> 00:12:41,920 Speaker 1: grad students spend dark bitter years working on it. Yeah. 246 00:12:41,960 --> 00:12:44,080 Speaker 1: So here's what people had to say. When I figure 247 00:12:44,080 --> 00:12:48,640 Speaker 1: of radiation, I think of waves being admitted from something, 248 00:12:48,679 --> 00:12:50,840 Speaker 1: so that could be heat radiation, or it could be 249 00:12:50,920 --> 00:12:56,000 Speaker 1: light radiation. And even when something is invisible light to 250 00:12:56,160 --> 00:13:01,160 Speaker 1: humans radiation, UM, it's still quote unquote light. So dark 251 00:13:01,280 --> 00:13:05,240 Speaker 1: radiation I imagine. I think it has something to do 252 00:13:05,280 --> 00:13:09,120 Speaker 1: with dark energy. Probably I have to give all credit 253 00:13:09,360 --> 00:13:11,640 Speaker 1: to no Degress Tyson for why I know this. But 254 00:13:12,320 --> 00:13:17,000 Speaker 1: dark radiation is the mediator of dark matter particle interaction. 255 00:13:17,480 --> 00:13:21,760 Speaker 1: Say that five times fast. The best analogy for it is, um, 256 00:13:21,760 --> 00:13:24,320 Speaker 1: it's the dark matter equivalent of a photon. I think 257 00:13:24,520 --> 00:13:28,760 Speaker 1: dark radiation is radiation coming from dark matter right away. 258 00:13:28,800 --> 00:13:31,880 Speaker 1: It makes me think of dark matter and dark energy, 259 00:13:31,960 --> 00:13:34,720 Speaker 1: and I know they both interact with regular matter only 260 00:13:34,720 --> 00:13:39,360 Speaker 1: through gravity. So I would guess that it has something 261 00:13:39,400 --> 00:13:45,520 Speaker 1: to do with how dark matter radiates away or evaporates 262 00:13:45,559 --> 00:13:48,360 Speaker 1: in the same manner regular mass does with like a 263 00:13:48,360 --> 00:13:52,720 Speaker 1: black hole. All right, some pretty good answers here, mostly questions. 264 00:13:53,160 --> 00:13:55,960 Speaker 1: I feel like people answered back with some questions too. Yeah, 265 00:13:55,960 --> 00:13:57,800 Speaker 1: and people get the sense that it has something to 266 00:13:57,880 --> 00:14:00,720 Speaker 1: do with dark matter or dark inner g right, because 267 00:14:00,760 --> 00:14:03,760 Speaker 1: people have this concept that radiation energy, and so maybe 268 00:14:03,760 --> 00:14:06,760 Speaker 1: it falls into the like energy category rather than the 269 00:14:06,840 --> 00:14:10,000 Speaker 1: dark matter category. So yeah, some great answers. Yeah, I 270 00:14:10,040 --> 00:14:13,040 Speaker 1: feel like you've really sort of branded that word dark, 271 00:14:13,200 --> 00:14:15,840 Speaker 1: Like people automatically anything you associated with the word dark, 272 00:14:15,920 --> 00:14:18,560 Speaker 1: people know it's oh dark matter or dark energy. Yeah. 273 00:14:18,559 --> 00:14:20,920 Speaker 1: The funny thing is that the word dark and physics 274 00:14:21,000 --> 00:14:23,800 Speaker 1: just means we don't know anything about it. It's like 275 00:14:24,000 --> 00:14:27,200 Speaker 1: hidden from us, something we can't see, and so like 276 00:14:27,240 --> 00:14:30,680 Speaker 1: the only relationship between dark matter and dark energy really 277 00:14:30,760 --> 00:14:33,000 Speaker 1: is that we're pretty clueless about both of them. Well, 278 00:14:33,040 --> 00:14:34,920 Speaker 1: my question is, what's gonna happen when you do discover 279 00:14:35,000 --> 00:14:36,680 Speaker 1: what it is and when you can see it. Do 280 00:14:36,720 --> 00:14:39,120 Speaker 1: you need to change the name. Oh, that's a great question. 281 00:14:39,280 --> 00:14:42,880 Speaker 1: It depends, I suppose, on whether it remains dark or not. 282 00:14:43,080 --> 00:14:45,280 Speaker 1: You know, if we find some way to communicate with 283 00:14:45,600 --> 00:14:48,840 Speaker 1: the dark sector with these dark particles, then they won't 284 00:14:48,960 --> 00:14:52,200 Speaker 1: any longer be totally dark. So yeah, because it depends 285 00:14:52,320 --> 00:14:54,640 Speaker 1: specifically on what we figure out about it. Well, you 286 00:14:54,720 --> 00:14:56,440 Speaker 1: just said that it's you call it dark when you 287 00:14:56,480 --> 00:14:58,120 Speaker 1: don't know anything about it. So if you do know 288 00:14:58,200 --> 00:15:00,600 Speaker 1: something about it and can't see it, maybe think about 289 00:15:00,640 --> 00:15:03,400 Speaker 1: changing the name to like, you know, Horhi matter or 290 00:15:03,760 --> 00:15:06,480 Speaker 1: cam matter, just saying, you know, some suggestions. We'll put 291 00:15:06,520 --> 00:15:08,680 Speaker 1: that on the list, right next to white chocolate matter. Yeah, 292 00:15:08,960 --> 00:15:10,520 Speaker 1: I just realized its kind of running for a guy 293 00:15:10,600 --> 00:15:13,760 Speaker 1: named white sun. It sounds like you have some father issues. Yeah, 294 00:15:13,840 --> 00:15:18,360 Speaker 1: self loathing matter, that's what it is. That's that's pretty dark. 295 00:15:18,480 --> 00:15:21,440 Speaker 1: That's pretty dark. I'm gonna go in some more dark 296 00:15:21,520 --> 00:15:23,880 Speaker 1: chocolate and now feel better. Alright, So Daniel, we're going 297 00:15:23,920 --> 00:15:26,280 Speaker 1: to answer this question. What is dark radiation? Which is 298 00:15:26,560 --> 00:15:30,239 Speaker 1: sounds very tantalizing, it sounds cool. It sounds maybe dangerous 299 00:15:30,560 --> 00:15:32,880 Speaker 1: dark radiation, or maybe dark radiation is good for you 300 00:15:32,920 --> 00:15:36,040 Speaker 1: because it's the opposite of regular radiation. It's not like 301 00:15:36,400 --> 00:15:39,080 Speaker 1: entire radiation like that. What you need is a dose 302 00:15:39,120 --> 00:15:41,600 Speaker 1: of dark radiation that'll cure Peter Parker, right, he'll no 303 00:15:41,640 --> 00:15:44,880 Speaker 1: longer be Spider Man. The you know, damage right out 304 00:15:44,880 --> 00:15:49,960 Speaker 1: of you. No, dark radiation is an analog to radiation, 305 00:15:50,400 --> 00:15:52,800 Speaker 1: but in dark matter. So in our kind of matter, 306 00:15:52,960 --> 00:15:55,240 Speaker 1: we have you know, electrons and quarks, and they can 307 00:15:55,480 --> 00:15:59,600 Speaker 1: radiate things like photons because there are forces between these particles, 308 00:15:59,720 --> 00:16:03,920 Speaker 1: and so dark radiation would imagine that between dark matter 309 00:16:04,000 --> 00:16:07,840 Speaker 1: particles there might be some new dark force, and that 310 00:16:07,960 --> 00:16:11,280 Speaker 1: new dark force would be capable of generating dark radiation. 311 00:16:12,400 --> 00:16:15,120 Speaker 1: But you know, I think technically in physics you use 312 00:16:15,160 --> 00:16:19,120 Speaker 1: the word radiation for basically any particle, any quantum particle 313 00:16:19,200 --> 00:16:21,360 Speaker 1: moving in a quantum field, right, I think that's isn't 314 00:16:21,400 --> 00:16:24,520 Speaker 1: that the technical definition? Unfortunately, we're not totally consistent that 315 00:16:24,680 --> 00:16:27,640 Speaker 1: when we talk about radiation. When we talk about radiation 316 00:16:27,680 --> 00:16:30,760 Speaker 1: sort of chemically like what is producing radiation, that can 317 00:16:30,800 --> 00:16:33,760 Speaker 1: include things like photons, but also, as you say, high 318 00:16:33,840 --> 00:16:36,800 Speaker 1: energy particles. Here, when we talk about radiation and we 319 00:16:36,840 --> 00:16:39,880 Speaker 1: distinguish it from matter, we're talking about the particles that 320 00:16:39,880 --> 00:16:43,160 Speaker 1: are associated with forces rather than the particles that are 321 00:16:43,160 --> 00:16:46,720 Speaker 1: associated with matter. So for example, a photon would be radiation, 322 00:16:47,000 --> 00:16:49,480 Speaker 1: whereas a cork would be matter. Even if a cork 323 00:16:49,560 --> 00:16:52,440 Speaker 1: moving at high speed, a chemist would call it radiation. 324 00:16:52,600 --> 00:16:55,000 Speaker 1: Oh I see, So if we're going with the chemist definition, 325 00:16:55,040 --> 00:16:58,360 Speaker 1: then radiation is just any particle moving kind of what 326 00:16:58,480 --> 00:17:01,200 Speaker 1: if you're going, if you're going with the day annual interpretation. Here, 327 00:17:01,400 --> 00:17:04,479 Speaker 1: radiation just means a force particle or like a particle 328 00:17:04,520 --> 00:17:07,480 Speaker 1: associated with a force moving through space. The idea is 329 00:17:07,520 --> 00:17:11,760 Speaker 1: that maybe dark matter also produces dark radiation. That's the idea, 330 00:17:11,840 --> 00:17:15,520 Speaker 1: and it's a really interesting area to study because you know, 331 00:17:15,560 --> 00:17:17,960 Speaker 1: we don't know what's going on with dark matter. We 332 00:17:18,040 --> 00:17:20,360 Speaker 1: just know that there's a lot of it in the universe. 333 00:17:20,560 --> 00:17:23,359 Speaker 1: But it's tempting to extrapolate from the kind of matter 334 00:17:23,400 --> 00:17:25,280 Speaker 1: that we have, right, the kind of matter we have 335 00:17:25,400 --> 00:17:28,520 Speaker 1: does all sorts of interesting crazy stuff. It feels forces, 336 00:17:28,800 --> 00:17:32,240 Speaker 1: it forms complex objects like ice cream and chocolate and pizza. 337 00:17:32,680 --> 00:17:34,800 Speaker 1: So we don't know what's going on with the dark matter. 338 00:17:35,000 --> 00:17:37,600 Speaker 1: There's various possibilities all the way from like it's totally 339 00:17:37,600 --> 00:17:39,920 Speaker 1: inert it feels no forces. It just sort of sits 340 00:17:39,960 --> 00:17:43,840 Speaker 1: there and feels gravity too. It has like seventy five 341 00:17:43,960 --> 00:17:47,520 Speaker 1: new forces we haven't even imagined. They're capable of forming intricate, 342 00:17:47,560 --> 00:17:52,040 Speaker 1: complex things that would blow our minds. And in that scenario, 343 00:17:52,280 --> 00:17:55,320 Speaker 1: those forces would be mediated by dark particles, and so 344 00:17:55,359 --> 00:17:58,040 Speaker 1: those would be dark radiation, right, Because I think all 345 00:17:58,080 --> 00:18:00,320 Speaker 1: we know about dark matter is that it it sort 346 00:18:00,359 --> 00:18:03,280 Speaker 1: of looks like it's a big giant, fuzzy clump. But 347 00:18:03,359 --> 00:18:04,879 Speaker 1: that's just what we can see of it. You know, 348 00:18:04,960 --> 00:18:08,359 Speaker 1: it could be something really detailed and organized. We just 349 00:18:08,400 --> 00:18:11,080 Speaker 1: have a very unfocused view of it. That's right, And 350 00:18:11,119 --> 00:18:13,840 Speaker 1: that's because so far, our only way to learn things 351 00:18:13,880 --> 00:18:16,800 Speaker 1: about dark matter, to interact with dark matter so as 352 00:18:16,840 --> 00:18:19,120 Speaker 1: to figure out like where it is and what it's doing, 353 00:18:19,560 --> 00:18:23,159 Speaker 1: is through gravity, and gravity is the weakest force in 354 00:18:23,200 --> 00:18:25,960 Speaker 1: the universe we've discovered, and not by a little bit, 355 00:18:26,000 --> 00:18:28,600 Speaker 1: but by like ten to the thirty six. It's like 356 00:18:28,720 --> 00:18:31,520 Speaker 1: super duper crazy week. So it's like trying to look 357 00:18:31,600 --> 00:18:35,040 Speaker 1: at dark matter, but you're looking through very very dark glasses, 358 00:18:35,080 --> 00:18:37,080 Speaker 1: so you can just barely see it. You can only 359 00:18:37,119 --> 00:18:39,520 Speaker 1: see huge clumps of it, and that gives us a 360 00:18:39,600 --> 00:18:42,199 Speaker 1: very fuzzy view of what's going on. The glasses are 361 00:18:42,240 --> 00:18:44,600 Speaker 1: made out of dark matter. I'm a little confused here. 362 00:18:44,960 --> 00:18:50,760 Speaker 1: They filter dark radiation. I think you mean like fuzzy glasses. Yeah, yeah, 363 00:18:50,880 --> 00:18:52,520 Speaker 1: all right, Well maybe for the people who are not 364 00:18:52,560 --> 00:18:55,080 Speaker 1: familiar with dark matter, maybe give us a quick refresher 365 00:18:55,200 --> 00:18:56,840 Speaker 1: of what it is and how we know it's there. 366 00:18:57,000 --> 00:18:59,040 Speaker 1: So we don't know that much about dark matter, but 367 00:18:59,080 --> 00:19:01,439 Speaker 1: we do know that it makes up most of the 368 00:19:01,480 --> 00:19:04,200 Speaker 1: stuff in the universe, and it's some kind of matter 369 00:19:04,520 --> 00:19:07,560 Speaker 1: by which we mean that it provides gravity. And you know, 370 00:19:07,600 --> 00:19:11,040 Speaker 1: we invented the idea of dark matter to explain why 371 00:19:11,080 --> 00:19:15,119 Speaker 1: there was gravity in the universe that we couldn't otherwise explain. So, 372 00:19:15,160 --> 00:19:18,600 Speaker 1: for example, we see that galaxies are rotating really really fast, 373 00:19:18,920 --> 00:19:21,960 Speaker 1: and there's apparently enough gravity to hold them together to 374 00:19:22,040 --> 00:19:24,920 Speaker 1: keep the stars from going out into interstellar space being 375 00:19:24,960 --> 00:19:27,760 Speaker 1: tossed out. But we can't explain where that gravity is 376 00:19:27,800 --> 00:19:30,840 Speaker 1: coming from, so we say probably dark matter. And if 377 00:19:30,840 --> 00:19:33,520 Speaker 1: we want to understand the structure of the universe, how 378 00:19:33,560 --> 00:19:36,439 Speaker 1: it got to have these galaxies and these superclusters and 379 00:19:36,440 --> 00:19:38,720 Speaker 1: all of this stuff. If you run a simulation of 380 00:19:38,760 --> 00:19:42,080 Speaker 1: the universe without dark matter, then it just doesn't form 381 00:19:42,160 --> 00:19:45,520 Speaker 1: galaxies and stars this quickly. You need more gravity to 382 00:19:45,600 --> 00:19:48,479 Speaker 1: pull that stuff together. So we need dark matter not 383 00:19:48,560 --> 00:19:51,399 Speaker 1: just to explain how galaxies are spinning, but also the 384 00:19:51,440 --> 00:19:54,440 Speaker 1: whole structure of the universe. And if we look in 385 00:19:54,520 --> 00:19:57,240 Speaker 1: the very early ever beginnings of the universe and we 386 00:19:57,280 --> 00:20:00,159 Speaker 1: see like how wiggles in the first plasma of the 387 00:20:00,280 --> 00:20:03,720 Speaker 1: universe formed, and how those wiggles propagated, they don't really 388 00:20:03,760 --> 00:20:07,720 Speaker 1: make sense unless you add dark matter to our calculations. 389 00:20:07,720 --> 00:20:09,560 Speaker 1: So we have a lot of evidence that dark matter 390 00:20:09,600 --> 00:20:11,880 Speaker 1: is a thing, that it's out there, that it clumps 391 00:20:11,960 --> 00:20:15,640 Speaker 1: together in these big structures that shaped our whole universe. 392 00:20:15,840 --> 00:20:18,040 Speaker 1: We just don't really know what it's made out of 393 00:20:18,040 --> 00:20:20,879 Speaker 1: other than something that gives gravity. Yeah, we we know 394 00:20:20,960 --> 00:20:22,880 Speaker 1: it's there and it has to be there to explain 395 00:20:22,960 --> 00:20:25,320 Speaker 1: what we see. But I think that's the crazy things 396 00:20:25,359 --> 00:20:27,840 Speaker 1: that we don't know what it is, Like, we really 397 00:20:27,840 --> 00:20:29,800 Speaker 1: have no idea, Like it could be a totally new 398 00:20:29,880 --> 00:20:32,240 Speaker 1: kind of thing that's not even a particle, or even 399 00:20:32,320 --> 00:20:35,040 Speaker 1: something sort of like cohesive. It could be anything, right, Yeah, 400 00:20:35,040 --> 00:20:37,440 Speaker 1: And we've done a lot of podcast episodes diving into 401 00:20:37,480 --> 00:20:40,560 Speaker 1: some of those examples. Sort Of the mainstream idea is 402 00:20:40,600 --> 00:20:44,439 Speaker 1: a whim weakly interacting massive particle that's sort of like, 403 00:20:44,520 --> 00:20:47,679 Speaker 1: you know, a generic idea like what's the simplest possible 404 00:20:47,680 --> 00:20:50,680 Speaker 1: explanation for dark matter? But there's lots of other more 405 00:20:50,720 --> 00:20:54,800 Speaker 1: exotic and fascinating ideas, from things like axions, these weird 406 00:20:54,920 --> 00:20:59,240 Speaker 1: heavy photons, to things like primordial black holes formed very 407 00:20:59,359 --> 00:21:02,480 Speaker 1: very early in the universe to things like super duper 408 00:21:02,560 --> 00:21:07,199 Speaker 1: long wave photons generated by dark stars. So we just 409 00:21:07,280 --> 00:21:08,880 Speaker 1: don't really know what it is. And as you say, 410 00:21:08,920 --> 00:21:12,200 Speaker 1: it might not even be a particle. It might be 411 00:21:12,280 --> 00:21:15,159 Speaker 1: that this whole idea of particles and fields and quantum 412 00:21:15,240 --> 00:21:18,000 Speaker 1: forces only applies to the little bit of the universe 413 00:21:18,040 --> 00:21:20,160 Speaker 1: that we've been studying for the last few hundred years, 414 00:21:20,200 --> 00:21:22,399 Speaker 1: and that you can't extrapolate to the rest of the 415 00:21:22,480 --> 00:21:24,679 Speaker 1: universe the same way you can't, like look at an 416 00:21:24,720 --> 00:21:27,159 Speaker 1: elephant's tail and assume the rest of the elephant is 417 00:21:27,200 --> 00:21:29,320 Speaker 1: like the tail. So it might be that we have 418 00:21:29,560 --> 00:21:33,160 Speaker 1: dramatic mind blowing lessons to be learned about dark matter, 419 00:21:33,560 --> 00:21:35,400 Speaker 1: or it could be super boring and just be one 420 00:21:35,440 --> 00:21:38,760 Speaker 1: particle that doesn't do anything. Some pretty extreme possibilities there. 421 00:21:39,119 --> 00:21:41,000 Speaker 1: But but are you saying that maybe, like maybe even 422 00:21:41,080 --> 00:21:44,400 Speaker 1: quantum mechanics only applies to a small part of the universe. 423 00:21:44,640 --> 00:21:46,560 Speaker 1: I think that's true. Yeah, All of the tests that 424 00:21:46,600 --> 00:21:49,879 Speaker 1: we've done of quantum mechanics use our kind of matter 425 00:21:50,080 --> 00:21:52,320 Speaker 1: and our kind of forces, and so we have a 426 00:21:52,320 --> 00:21:56,000 Speaker 1: pretty good quantum description of quantum particles, but we don't 427 00:21:56,000 --> 00:21:59,399 Speaker 1: really have a quantum description of gravity and gravity is 428 00:21:59,440 --> 00:22:01,439 Speaker 1: our poor to dark matter. The only thing we know 429 00:22:01,480 --> 00:22:04,359 Speaker 1: about dark matter is that it does feel gravity, and 430 00:22:04,400 --> 00:22:06,800 Speaker 1: so it could be some other new, weird kind of 431 00:22:06,920 --> 00:22:11,119 Speaker 1: thing that generates gravity but doesn't otherwise follow the rules 432 00:22:11,119 --> 00:22:15,520 Speaker 1: of quantum mechanics. Well, all right, so that's a dark matter. Now, 433 00:22:15,560 --> 00:22:18,800 Speaker 1: what would you say is a dark force? Besides the 434 00:22:18,840 --> 00:22:22,600 Speaker 1: obvious Star Wars reference, a dark force would be anybody 435 00:22:22,600 --> 00:22:26,280 Speaker 1: who tries to force me to eat white chocolate, the 436 00:22:26,400 --> 00:22:29,320 Speaker 1: dark force in my life. Now, a dark force would 437 00:22:29,320 --> 00:22:32,159 Speaker 1: be in the assumption that dark matter is made of 438 00:22:32,200 --> 00:22:36,280 Speaker 1: particles that follow the rules of quantum mechanics like our particles, 439 00:22:36,720 --> 00:22:39,240 Speaker 1: then you might imagine that they also feel some dark 440 00:22:39,320 --> 00:22:43,000 Speaker 1: forces between them. You know that too. Dark matter particles 441 00:22:43,000 --> 00:22:47,040 Speaker 1: can exchange some like dark photon or dark z boson 442 00:22:47,240 --> 00:22:50,199 Speaker 1: or dark higgs boson that they can like push or 443 00:22:50,240 --> 00:22:52,159 Speaker 1: pull on each other. They can do more than just 444 00:22:52,280 --> 00:22:55,679 Speaker 1: feel each other's gravity. Maybe there's some additional dark forces 445 00:22:55,760 --> 00:22:58,200 Speaker 1: and they're passing particles back and forth as a way 446 00:22:58,200 --> 00:23:01,040 Speaker 1: to mediate those forces. Rights. Even the matter in our 447 00:23:01,119 --> 00:23:04,280 Speaker 1: universe is sort of selective about which forces it feels 448 00:23:04,359 --> 00:23:07,760 Speaker 1: or which forces they give out, right, Like some particles 449 00:23:07,800 --> 00:23:11,679 Speaker 1: in our type of matter only feel like the magnetic forces, 450 00:23:11,800 --> 00:23:14,159 Speaker 1: or they don't feel the strong force and things like that. Right, 451 00:23:14,280 --> 00:23:17,800 Speaker 1: that's exactly right. Neutrinos, for example, only feel the weak force. 452 00:23:17,960 --> 00:23:22,440 Speaker 1: They ignore the strong force, they ignore electromagnetism. Electrons they 453 00:23:22,560 --> 00:23:25,719 Speaker 1: do feel electromagnetism and the weak force, but they ignore 454 00:23:25,760 --> 00:23:28,680 Speaker 1: the strong force. Only the corks feel all of the forces, 455 00:23:28,800 --> 00:23:32,040 Speaker 1: including the strong force. And so for an individual particle, 456 00:23:32,119 --> 00:23:34,680 Speaker 1: you can ask, like whether it has a charge for 457 00:23:34,760 --> 00:23:38,720 Speaker 1: that force. So electromagnetism only interact with particles that have 458 00:23:38,840 --> 00:23:41,960 Speaker 1: electric charges. For example, we know that dark matter doesn't 459 00:23:41,960 --> 00:23:44,600 Speaker 1: have electric charges, and it doesn't have weak charges, or 460 00:23:44,640 --> 00:23:47,680 Speaker 1: it doesn't have strong charges, but it might have charges 461 00:23:47,760 --> 00:23:51,199 Speaker 1: for other forces we haven't yet discovered. Wow, like there 462 00:23:51,240 --> 00:23:54,000 Speaker 1: could be a whole different category of forces that we 463 00:23:54,119 --> 00:23:56,680 Speaker 1: just don't happen to feel in our kind of matter, 464 00:23:57,040 --> 00:23:59,359 Speaker 1: but that maybe dark matter it does feel exactly So 465 00:23:59,400 --> 00:24:02,359 Speaker 1: there could be like one or forty new forces that 466 00:24:02,400 --> 00:24:05,480 Speaker 1: we haven't yet discovered because our particles don't feel those, 467 00:24:05,800 --> 00:24:09,000 Speaker 1: or maybe more, not just forty, maybe four thousand exactly. 468 00:24:11,119 --> 00:24:13,200 Speaker 1: All right, Well, let's dig into what this new kind 469 00:24:13,200 --> 00:24:16,000 Speaker 1: of force might be, this dark force and what it 470 00:24:16,080 --> 00:24:17,960 Speaker 1: could all mean and whether or not we can never 471 00:24:18,000 --> 00:24:20,760 Speaker 1: hope to see it or feel it. But first let's 472 00:24:20,760 --> 00:24:35,920 Speaker 1: take a quick break. All right, we're talking about dark radiation, 473 00:24:36,080 --> 00:24:37,919 Speaker 1: and in this case, the word radiation sort of is 474 00:24:37,920 --> 00:24:40,920 Speaker 1: associated with the word force. So really we're asking does 475 00:24:41,000 --> 00:24:45,080 Speaker 1: dark matter feel dark forces that maybe are out there, 476 00:24:45,080 --> 00:24:47,399 Speaker 1: but that we in our kind of matter can feel 477 00:24:47,480 --> 00:24:49,960 Speaker 1: or touch or detect. But then maybe it is maybe 478 00:24:50,160 --> 00:24:53,720 Speaker 1: organizing dark matter into structures or maybe you know, even 479 00:24:53,800 --> 00:24:57,400 Speaker 1: making dark matter particles and Adams exactly. And it's part 480 00:24:57,440 --> 00:25:00,439 Speaker 1: of this imagination game we play, you know, we wonder 481 00:25:00,520 --> 00:25:03,320 Speaker 1: what's going on out there in the dark universe. Is 482 00:25:03,320 --> 00:25:06,600 Speaker 1: it simple, is it fascinating, is it complex? What is 483 00:25:06,640 --> 00:25:09,320 Speaker 1: going on? What is they're out there to learn? And 484 00:25:09,560 --> 00:25:11,879 Speaker 1: usually when we go out and explore the universe, we 485 00:25:11,960 --> 00:25:16,120 Speaker 1: find that things are crazier and more fascinating and richer 486 00:25:16,280 --> 00:25:19,120 Speaker 1: than we ever imagined. And so we're at this point 487 00:25:19,160 --> 00:25:21,240 Speaker 1: where we really don't know about most of the universe. 488 00:25:21,280 --> 00:25:22,840 Speaker 1: But at some point in the future, I hope a 489 00:25:22,920 --> 00:25:25,000 Speaker 1: hundred years, five hundred years from now, we will know 490 00:25:25,040 --> 00:25:27,600 Speaker 1: what's going on in the dark sector and those people 491 00:25:27,680 --> 00:25:31,159 Speaker 1: will look back at our ideas as ridiculous. Probably you 492 00:25:31,240 --> 00:25:34,080 Speaker 1: might think of us as the Dark Ages physics. They 493 00:25:34,280 --> 00:25:36,800 Speaker 1: like the really dark ages, not that the trial run 494 00:25:36,840 --> 00:25:40,760 Speaker 1: in the Middle Ages, but more serious. Yes, back when 495 00:25:40,760 --> 00:25:45,359 Speaker 1: people ate white chocolate, that's right. Maybe we're looking forward 496 00:25:45,400 --> 00:25:50,000 Speaker 1: to an age of dark enlightenment, in the age of oxymorons. 497 00:25:50,160 --> 00:25:52,719 Speaker 1: But yeah, So in our kind of matter, we feel 498 00:25:52,880 --> 00:25:56,879 Speaker 1: the electromagnetic force, which is what basically holds our atoms together. 499 00:25:57,040 --> 00:25:58,760 Speaker 1: And what you know when you touch something, when you 500 00:25:58,800 --> 00:26:01,199 Speaker 1: touch the table or you hold the banana, that's the 501 00:26:01,200 --> 00:26:04,479 Speaker 1: force you're feeling. And that force is transmitted by a 502 00:26:04,520 --> 00:26:07,199 Speaker 1: particle called the photon. So the photon is not just 503 00:26:07,320 --> 00:26:10,960 Speaker 1: lighted Tosso what transmits the electromagnetic force? And so the 504 00:26:11,040 --> 00:26:13,919 Speaker 1: question daniel I guess is does dark matter have the 505 00:26:13,960 --> 00:26:17,520 Speaker 1: equivalent of a photon or at least an electromagnetic force field. 506 00:26:17,680 --> 00:26:20,000 Speaker 1: We just don't know, and so we're playing this game 507 00:26:20,040 --> 00:26:22,639 Speaker 1: of trying to extrapolate from what we do know. And 508 00:26:22,640 --> 00:26:25,280 Speaker 1: in the same way that we imagine maybe dark matter 509 00:26:25,560 --> 00:26:28,399 Speaker 1: is made of a particle, because we're made of particles, 510 00:26:28,520 --> 00:26:31,480 Speaker 1: we wonder if there are dark forces that look like 511 00:26:31,600 --> 00:26:34,800 Speaker 1: our forces. And so one of the simplest forces to 512 00:26:34,880 --> 00:26:38,520 Speaker 1: understand is electromagnetism because it just has like one particle 513 00:26:38,600 --> 00:26:41,159 Speaker 1: and it interacts with lots of stuff, and so a 514 00:26:41,280 --> 00:26:44,600 Speaker 1: simple proposals to say, well, what if dark matter has 515 00:26:44,640 --> 00:26:48,840 Speaker 1: a dark electromagnetism, meaning a dark photon. This would be 516 00:26:48,880 --> 00:26:51,399 Speaker 1: a particle that has a lot of properties similar to 517 00:26:51,560 --> 00:26:54,639 Speaker 1: our photon, but it would be different. You know, those 518 00:26:54,720 --> 00:26:58,160 Speaker 1: dark matter particles would have like a dark electric charge 519 00:26:58,480 --> 00:27:01,080 Speaker 1: and the dark photon, but only interact with particles with 520 00:27:01,160 --> 00:27:04,760 Speaker 1: a dark electric charge, not ones with our electric charge 521 00:27:05,040 --> 00:27:09,080 Speaker 1: and our normal vanilla photons wouldn't interact with dark matter 522 00:27:09,160 --> 00:27:12,040 Speaker 1: because they don't have an electric charge, only a dark 523 00:27:12,160 --> 00:27:16,080 Speaker 1: electric charge. But it wouldn't necessarily be the same or 524 00:27:16,119 --> 00:27:19,000 Speaker 1: the sort of the analog of light. Right you're just 525 00:27:19,000 --> 00:27:21,199 Speaker 1: saying like, maybe it's a force, and let's why not 526 00:27:21,359 --> 00:27:23,960 Speaker 1: let's qual it the dark electromagnetic force. It doesn't have 527 00:27:24,040 --> 00:27:26,040 Speaker 1: to be, and it could be the dark matter fields 528 00:27:26,080 --> 00:27:28,439 Speaker 1: forces that are more similar to like our weak force, 529 00:27:28,800 --> 00:27:31,040 Speaker 1: or forces that are more similar to our strong force, 530 00:27:31,400 --> 00:27:34,000 Speaker 1: or forces that are totally different from these forces and 531 00:27:34,080 --> 00:27:37,560 Speaker 1: have other new weird capacities. Right before we discovered the 532 00:27:37,600 --> 00:27:41,399 Speaker 1: strong force, who could have imagined this crazy force, you know, 533 00:27:41,440 --> 00:27:43,960 Speaker 1: where it gets stronger as things get further apart, and 534 00:27:43,960 --> 00:27:46,639 Speaker 1: it has like eight different kinds of gluons pulling it together. 535 00:27:46,920 --> 00:27:49,640 Speaker 1: It's bonkers. Nobody would have written that into the script. 536 00:27:49,880 --> 00:27:52,320 Speaker 1: So it's possible that there are other kinds of forces. 537 00:27:52,440 --> 00:27:54,960 Speaker 1: But if there is a dark force that's very similar 538 00:27:55,040 --> 00:27:58,360 Speaker 1: to electromagnetism, then that dark photon would have properties very 539 00:27:58,359 --> 00:28:01,399 Speaker 1: similar to our photon, because those properties come from the 540 00:28:01,400 --> 00:28:04,800 Speaker 1: structure of the force, all right. And also it makes 541 00:28:04,800 --> 00:28:07,560 Speaker 1: for a cool name, dark photon, because it kind of 542 00:28:07,600 --> 00:28:09,840 Speaker 1: it trips up your brain, right, Like, how can a 543 00:28:09,840 --> 00:28:13,080 Speaker 1: photon which transmits light be dark? That's right, because it 544 00:28:13,119 --> 00:28:18,200 Speaker 1: transmits dark light into dark eyeballs. Oh yeah, I feel 545 00:28:18,200 --> 00:28:20,119 Speaker 1: like you should maybe just call it something different. What 546 00:28:20,160 --> 00:28:23,240 Speaker 1: would you call it the dark on the invisible photon? 547 00:28:23,320 --> 00:28:25,240 Speaker 1: I don't know, dark on is good, But then what 548 00:28:25,280 --> 00:28:27,679 Speaker 1: do you find another force? Yeah, we'll have to be 549 00:28:27,720 --> 00:28:30,320 Speaker 1: even more creative with our names. We'll just have, you know, 550 00:28:30,400 --> 00:28:32,560 Speaker 1: a brainstorming session with lots of chocolate, and we'll come 551 00:28:32,640 --> 00:28:35,080 Speaker 1: up with something good and then and then who knows 552 00:28:35,080 --> 00:28:36,840 Speaker 1: what you'll get out of it? Maybe a heart attack, 553 00:28:37,080 --> 00:28:39,640 Speaker 1: all right? So dark matter might feel this new kind 554 00:28:39,680 --> 00:28:42,360 Speaker 1: of or strange new kind of force, a dark force. 555 00:28:42,600 --> 00:28:44,960 Speaker 1: So how would we ever detected Daniel, would we ever 556 00:28:45,000 --> 00:28:47,480 Speaker 1: hope to feel it or you know, know it's there 557 00:28:47,520 --> 00:28:49,600 Speaker 1: if we can't touch it or see it. So in 558 00:28:49,640 --> 00:28:53,080 Speaker 1: the end, this question is really asking what dark matter 559 00:28:53,200 --> 00:28:56,640 Speaker 1: does to itself? You know, can we speculate about what's 560 00:28:56,640 --> 00:28:59,400 Speaker 1: going on in the dark sector beyond these particles existing 561 00:28:59,680 --> 00:29:02,920 Speaker 1: can like touch each other and become sticky and do stuff, 562 00:29:03,000 --> 00:29:05,160 Speaker 1: And so we have sort of two ways to probe this. 563 00:29:05,360 --> 00:29:07,400 Speaker 1: The first category is sort of like indirect ways to 564 00:29:07,440 --> 00:29:10,120 Speaker 1: look at it, and broadly speaking, we can tell that 565 00:29:10,240 --> 00:29:13,040 Speaker 1: dark matter is doing things because of its gravity. And 566 00:29:13,240 --> 00:29:15,840 Speaker 1: even though it's not a great way to study dark matter, 567 00:29:16,120 --> 00:29:19,040 Speaker 1: we can use its gravitational effects to ask questions like 568 00:29:19,440 --> 00:29:22,680 Speaker 1: is it clumping? Is it interacting with itself? Because if 569 00:29:22,680 --> 00:29:25,400 Speaker 1: it interacts with itself, it forms sort of different structures 570 00:29:25,400 --> 00:29:27,840 Speaker 1: that have different gravity. So we can sort of ask 571 00:29:27,920 --> 00:29:30,800 Speaker 1: questions about whether dark matter is feeling itself by trying 572 00:29:30,840 --> 00:29:33,960 Speaker 1: to look to see how it organizes itself in the universe. 573 00:29:34,240 --> 00:29:36,840 Speaker 1: I see, we can't maybe see it directly or touch 574 00:29:37,000 --> 00:29:40,200 Speaker 1: dark matter, but if we can somehow kind of know 575 00:29:40,280 --> 00:29:42,120 Speaker 1: what it's doing, And if we see it doing stuff 576 00:29:42,120 --> 00:29:44,400 Speaker 1: to itself, then we know that it's there must be 577 00:29:44,440 --> 00:29:47,280 Speaker 1: some kind of force that it does interact with exactly. 578 00:29:47,360 --> 00:29:50,080 Speaker 1: For example, if dark matter felt a version of the 579 00:29:50,120 --> 00:29:53,120 Speaker 1: strong force, if it interacted with itself very very strongly 580 00:29:53,200 --> 00:29:56,400 Speaker 1: and could like clump together very very very sticky ways, 581 00:29:56,600 --> 00:29:59,200 Speaker 1: then it would form much denser objects than we see 582 00:29:59,240 --> 00:30:03,000 Speaker 1: currently in the universe. Currently, dark matter looks really big 583 00:30:03,040 --> 00:30:06,640 Speaker 1: and fluffy, like the dark matter in our galaxy isn't 584 00:30:06,640 --> 00:30:09,400 Speaker 1: nearly as compact as the normal matter in our galaxy. 585 00:30:09,440 --> 00:30:12,320 Speaker 1: It spreads out much further out. It's a big, fluffy 586 00:30:12,360 --> 00:30:16,000 Speaker 1: cloud hasn't collapsed nearly as much, and we think that's 587 00:30:16,040 --> 00:30:19,640 Speaker 1: because it's not as sticky as our matter. We think 588 00:30:19,640 --> 00:30:22,400 Speaker 1: that it doesn't feel like a super powerful force that 589 00:30:22,520 --> 00:30:25,000 Speaker 1: sticks it together, because that would help it like form 590 00:30:25,120 --> 00:30:28,640 Speaker 1: denser objects like dark planets and dark stars. So we 591 00:30:28,680 --> 00:30:32,520 Speaker 1: already know very broadly something about how dark matter can't 592 00:30:32,640 --> 00:30:35,840 Speaker 1: feel itself because it stays sort of fluffy and doesn't 593 00:30:35,880 --> 00:30:38,040 Speaker 1: seem to clump as much as normal matter. Right, But 594 00:30:38,080 --> 00:30:40,160 Speaker 1: I wonder you know it sort of looks fluffy to 595 00:30:40,240 --> 00:30:42,280 Speaker 1: us because we don't have a good way of seeing it. 596 00:30:42,360 --> 00:30:44,560 Speaker 1: You know, we talked earlier about having we kind of 597 00:30:44,600 --> 00:30:47,000 Speaker 1: have a fuzzy lens when we look at dark matter 598 00:30:47,360 --> 00:30:50,040 Speaker 1: because we can only see it through gravity. You know, 599 00:30:50,160 --> 00:30:52,600 Speaker 1: is it maybe even possible that there are dark matter 600 00:30:52,640 --> 00:30:55,760 Speaker 1: stars out there, which is don't have the resolution to 601 00:30:55,840 --> 00:30:58,040 Speaker 1: see them. You know, absolutely, there's a very big loophole 602 00:30:58,040 --> 00:30:59,840 Speaker 1: in this argument that you allude to, which is that 603 00:31:00,040 --> 00:31:02,040 Speaker 1: you can see sort of the bulk of dark matter, 604 00:31:02,080 --> 00:31:04,960 Speaker 1: but we can't tell what it's doing in detail. In 605 00:31:04,960 --> 00:31:08,040 Speaker 1: an episode recently about where is the dark matter, and 606 00:31:08,080 --> 00:31:09,880 Speaker 1: we talked about how we can tell sort of the 607 00:31:10,000 --> 00:31:12,600 Speaker 1: dark matters in these big fluffy clouds, but we also 608 00:31:12,720 --> 00:31:15,280 Speaker 1: can't really tell if it is forming clumps. So you 609 00:31:15,280 --> 00:31:17,920 Speaker 1: could imagine that dark matter maybe it's made out of 610 00:31:17,960 --> 00:31:20,320 Speaker 1: a few different kinds of things. So most of it, 611 00:31:20,360 --> 00:31:22,160 Speaker 1: maybe like you know, half of the dark matter or 612 00:31:22,160 --> 00:31:24,440 Speaker 1: three fourths of the dark matter, is some big, fluffy 613 00:31:24,480 --> 00:31:26,840 Speaker 1: stuff that hardly interacts with itself. But there could be 614 00:31:26,880 --> 00:31:30,160 Speaker 1: a component of the dark matter that does do interesting, 615 00:31:30,280 --> 00:31:34,280 Speaker 1: complicated things and has crazy interactions and forms dark stars 616 00:31:34,280 --> 00:31:36,760 Speaker 1: and dark planets and dark life, and that would not 617 00:31:36,920 --> 00:31:39,920 Speaker 1: mess up the distribution of dark matter, because remember, there's 618 00:31:40,000 --> 00:31:43,360 Speaker 1: like so much dark matter out there that even like 619 00:31:43,640 --> 00:31:46,640 Speaker 1: if a quarter of it does more interesting stuff, that's 620 00:31:46,680 --> 00:31:49,320 Speaker 1: still more than all of our kind of matter. So 621 00:31:49,360 --> 00:31:51,760 Speaker 1: there's plenty of room to have like a component that 622 00:31:51,800 --> 00:31:55,760 Speaker 1: has complex interactions without missing up these constraints about the 623 00:31:55,840 --> 00:31:58,120 Speaker 1: big picture of dark matter. So I feel like dark 624 00:31:58,120 --> 00:31:59,960 Speaker 1: matter could be in the shape of I don't know, 625 00:32:00,120 --> 00:32:03,640 Speaker 1: like rubber duckies. It's just that they're sort of distributed 626 00:32:03,640 --> 00:32:06,440 Speaker 1: out in space, these rubber duckies, and to us it 627 00:32:06,440 --> 00:32:08,920 Speaker 1: just seems like a big fluffy cloud. Yeah, most of 628 00:32:08,960 --> 00:32:10,840 Speaker 1: it has to be pretty big and fluffy to form 629 00:32:10,880 --> 00:32:13,720 Speaker 1: that big fluffy cloud. It can't stick to itself. But 630 00:32:13,800 --> 00:32:16,480 Speaker 1: it could be that inside that big fluffy cloud there 631 00:32:16,520 --> 00:32:19,040 Speaker 1: are like rubber duckies made out of like a special 632 00:32:19,160 --> 00:32:21,080 Speaker 1: kind of dark matter, you know, the way they like 633 00:32:21,160 --> 00:32:23,800 Speaker 1: our matter. There's lots of different kinds is electrons, is 634 00:32:23,840 --> 00:32:27,360 Speaker 1: different kinds of quarks. Right, we have twelve different matter particles. 635 00:32:27,720 --> 00:32:30,240 Speaker 1: Dark matter could have like fifty different kinds of particles, 636 00:32:30,240 --> 00:32:32,520 Speaker 1: and maybe most of them don't interact and make a 637 00:32:32,520 --> 00:32:35,160 Speaker 1: big fluffy cloud, but one or two of them form 638 00:32:35,320 --> 00:32:37,840 Speaker 1: dark rubber duckies that are floating out there in the universe, 639 00:32:37,840 --> 00:32:40,080 Speaker 1: and we couldn't tell the difference because the only way 640 00:32:40,120 --> 00:32:43,640 Speaker 1: we can see them is through their overall gravitational interaction. 641 00:32:43,680 --> 00:32:46,240 Speaker 1: I'm pretty sure that's what dark Vader uses in his bathtuff. 642 00:32:46,560 --> 00:32:48,760 Speaker 1: But I guess the question is, you know, isn't the 643 00:32:48,800 --> 00:32:51,000 Speaker 1: fact that dark matter does seem to be sort of 644 00:32:51,040 --> 00:32:53,720 Speaker 1: fluffy and doesn't seem to stick to itself. Is that 645 00:32:53,760 --> 00:32:57,120 Speaker 1: evidence that maybe it doesn't interact with itself other than 646 00:32:57,160 --> 00:32:59,880 Speaker 1: with gravity. It's evidence that it doesn't interact with itself 647 00:33:00,160 --> 00:33:03,200 Speaker 1: very very strongly. But again, the loophole is that some 648 00:33:03,360 --> 00:33:05,880 Speaker 1: component of it might be able to Now. The way 649 00:33:05,880 --> 00:33:08,080 Speaker 1: to probe that a little bit more deeply is to 650 00:33:08,080 --> 00:33:11,040 Speaker 1: do experiments. Is to take like two big clouds of 651 00:33:11,120 --> 00:33:13,960 Speaker 1: dark matter and throw them against each other and see 652 00:33:14,320 --> 00:33:16,560 Speaker 1: if they pass right through each other, or if maybe 653 00:33:16,560 --> 00:33:19,200 Speaker 1: they stick together and make them like dark explosions. That 654 00:33:19,280 --> 00:33:22,080 Speaker 1: kind of experiment is pretty tough to do, but we 655 00:33:22,080 --> 00:33:24,320 Speaker 1: were lucky and the universe did it for us. It 656 00:33:24,480 --> 00:33:28,760 Speaker 1: collided two huge clusters of galaxies, each of which have 657 00:33:28,880 --> 00:33:32,320 Speaker 1: their own dark matter associated with them, smashed them together 658 00:33:32,400 --> 00:33:34,200 Speaker 1: millions of years ago, and we got to see what 659 00:33:34,280 --> 00:33:36,400 Speaker 1: happened and what did happen, and so this is called 660 00:33:36,400 --> 00:33:38,200 Speaker 1: the bullet cluster. You can go ahead and look at 661 00:33:38,240 --> 00:33:41,480 Speaker 1: these pictures online if you're interested. It's really beautiful. What 662 00:33:41,600 --> 00:33:44,880 Speaker 1: happened is that the stars in these galaxy clusters mostly 663 00:33:44,920 --> 00:33:47,920 Speaker 1: passed through themselves because stars are pretty sparse, so it's 664 00:33:47,920 --> 00:33:50,480 Speaker 1: like two clouds of sand passing through each other. The 665 00:33:50,600 --> 00:33:53,320 Speaker 1: gas and the dust that were in these galaxies smashed 666 00:33:53,360 --> 00:33:55,800 Speaker 1: together and admitted a lot of light and radiation. But 667 00:33:55,840 --> 00:33:59,120 Speaker 1: the dark matter looks like it basically passed right through itself. 668 00:33:59,520 --> 00:34:01,360 Speaker 1: You might ask school like, how could we know where 669 00:34:01,360 --> 00:34:03,240 Speaker 1: the dark matter is? We can see the dark matter 670 00:34:03,280 --> 00:34:06,040 Speaker 1: because it distorts the stuff behind it. From the dark 671 00:34:06,080 --> 00:34:09,240 Speaker 1: matter is matter, it feels gravity, so it bends space 672 00:34:09,280 --> 00:34:12,759 Speaker 1: a little bit, which creates like gravitational distortions in the 673 00:34:12,840 --> 00:34:15,960 Speaker 1: light that passes through it. So from this bullet cluster, 674 00:34:16,040 --> 00:34:18,719 Speaker 1: it looks like these two clouds mostly passed right through 675 00:34:18,760 --> 00:34:21,840 Speaker 1: each other. So not it doesn't have any strong interactions 676 00:34:21,840 --> 00:34:24,200 Speaker 1: with itself, but it could still have some interactions with itself, 677 00:34:24,239 --> 00:34:27,200 Speaker 1: which would maybe give rise to something like a dark photon. 678 00:34:27,360 --> 00:34:30,000 Speaker 1: That's right, and so people often cite the bullet cluster 679 00:34:30,080 --> 00:34:32,760 Speaker 1: is evidence that dark matter can't feel anything with itself, 680 00:34:32,840 --> 00:34:35,600 Speaker 1: and that's not exactly true, because, as you say, there's 681 00:34:35,600 --> 00:34:38,240 Speaker 1: still room in there for some kind of interaction. Because 682 00:34:38,320 --> 00:34:41,640 Speaker 1: remember that the stars, which do definitely feel each other, 683 00:34:41,800 --> 00:34:45,040 Speaker 1: also passed right through themselves. Right. The star is hardly collided, 684 00:34:45,280 --> 00:34:47,960 Speaker 1: and that's just because it's pretty sparse, and so could 685 00:34:48,000 --> 00:34:50,719 Speaker 1: be that dark matter forms the structures, but they didn't 686 00:34:50,719 --> 00:34:53,439 Speaker 1: collide with each other because just like the stars, they're 687 00:34:53,480 --> 00:34:56,160 Speaker 1: pretty sparse and space is pretty big. And it could 688 00:34:56,200 --> 00:34:58,919 Speaker 1: also be that some components of the dark matter did 689 00:34:58,960 --> 00:35:01,600 Speaker 1: collide with itself, did get stuck sort of in the 690 00:35:01,600 --> 00:35:04,080 Speaker 1: middle there. But we don't really have the resolution to tell. 691 00:35:04,160 --> 00:35:07,600 Speaker 1: We can't very precisely measure how much dark matter passed 692 00:35:07,600 --> 00:35:09,640 Speaker 1: through and how much stuck. We can just tell that 693 00:35:09,680 --> 00:35:12,600 Speaker 1: a lot of it passed through, but some component could 694 00:35:12,600 --> 00:35:14,920 Speaker 1: have gotten stuck and could be doing like crazy stuff 695 00:35:14,920 --> 00:35:17,000 Speaker 1: there in the middle. I see, like maybe the Rubert 696 00:35:17,040 --> 00:35:19,279 Speaker 1: duckies didn't all crash into each other, but some just 697 00:35:19,360 --> 00:35:22,040 Speaker 1: kept going. I think the key point to understand is 698 00:35:22,040 --> 00:35:25,080 Speaker 1: that there's so much dark matter out there that even 699 00:35:25,080 --> 00:35:27,680 Speaker 1: if a tiny fraction of it is doing interesting things 700 00:35:28,000 --> 00:35:30,520 Speaker 1: we couldn't tell, and that tiny fraction would still be 701 00:35:30,560 --> 00:35:32,960 Speaker 1: more stuff than all of the stars and gas and 702 00:35:33,040 --> 00:35:34,920 Speaker 1: dust in the universe that we know. All right, well, 703 00:35:35,000 --> 00:35:36,680 Speaker 1: let's get into other ways that we might be able 704 00:35:36,719 --> 00:35:39,839 Speaker 1: to detect this dark radiation and maybe even see these 705 00:35:39,920 --> 00:35:42,319 Speaker 1: dark or not see these dark photons. I'm a little 706 00:35:42,320 --> 00:35:44,960 Speaker 1: confused about how he might see are not photon But 707 00:35:45,000 --> 00:35:59,799 Speaker 1: first let's take another quick break. All right, we're talking 708 00:35:59,800 --> 00:36:03,560 Speaker 1: abot dark gradiation and dark photons, which it might be 709 00:36:03,680 --> 00:36:06,560 Speaker 1: what dark matter sees and feels with itself when dark 710 00:36:06,600 --> 00:36:08,319 Speaker 1: matter looks in the mirror. That's what they would see 711 00:36:08,400 --> 00:36:12,440 Speaker 1: dark photons. Yeah, exactly. I hope they haven't eating too 712 00:36:12,480 --> 00:36:15,000 Speaker 1: much dark chocolate. But to us it's pretty elusive because 713 00:36:15,000 --> 00:36:18,279 Speaker 1: we can see or feel the dark matter or maybe 714 00:36:18,320 --> 00:36:20,719 Speaker 1: even these forces. So, Daniel, what are some of the 715 00:36:20,760 --> 00:36:23,360 Speaker 1: other ways that we might hope to detect whether or 716 00:36:23,360 --> 00:36:26,200 Speaker 1: not dark matter has these dark interactions. There are a 717 00:36:26,320 --> 00:36:30,360 Speaker 1: couple other indirect ways, basically again using gravity. One of 718 00:36:30,360 --> 00:36:34,360 Speaker 1: them is looking at neutron stars. Neutron stars are these 719 00:36:34,440 --> 00:36:37,880 Speaker 1: crazy dense objects that are the remnants of stars that 720 00:36:37,920 --> 00:36:40,640 Speaker 1: have blown up and left this very very compact core, 721 00:36:41,200 --> 00:36:44,399 Speaker 1: and sometimes neutron stars come in pairs and then those 722 00:36:44,440 --> 00:36:47,279 Speaker 1: pairs spin around each other in this sort of like 723 00:36:47,360 --> 00:36:50,400 Speaker 1: death spiral before they collide, and when they do that, 724 00:36:50,440 --> 00:36:53,839 Speaker 1: they create gravitational waves that we can see here from Earth. 725 00:36:53,880 --> 00:36:57,239 Speaker 1: This is like the shaking of space itself. If you're 726 00:36:57,520 --> 00:36:59,200 Speaker 1: interested in learning more about that, we have a couple 727 00:36:59,200 --> 00:37:02,239 Speaker 1: of episodes about gravitational waves. It's really cool because the 728 00:37:02,280 --> 00:37:06,360 Speaker 1: gravitational waves reveal in detail how these stars are spiraling 729 00:37:06,480 --> 00:37:09,560 Speaker 1: towards the center, how they're losing energy, and we can 730 00:37:09,560 --> 00:37:12,520 Speaker 1: calculate with great precision how fast they should be going 731 00:37:12,560 --> 00:37:14,960 Speaker 1: and how much energy they're losing. And so this is 732 00:37:14,960 --> 00:37:17,120 Speaker 1: a really nice test of sort of like what's going 733 00:37:17,200 --> 00:37:19,840 Speaker 1: on with this kind of matter, Because if these neutron 734 00:37:19,960 --> 00:37:24,080 Speaker 1: stars were capable, for example, of feeling this dark radiation 735 00:37:24,200 --> 00:37:27,320 Speaker 1: at some level, if the particles in there could feel 736 00:37:27,320 --> 00:37:29,839 Speaker 1: this force at all, then they would radiate a little 737 00:37:29,840 --> 00:37:32,400 Speaker 1: bit of those dark photons and it would change the 738 00:37:32,440 --> 00:37:34,920 Speaker 1: way this inspiral happens, and we would be able to 739 00:37:34,920 --> 00:37:37,880 Speaker 1: see that by looking at the gravitational waves. Wait, so 740 00:37:38,000 --> 00:37:40,439 Speaker 1: these neutron stars would be made out of regular matter, 741 00:37:40,560 --> 00:37:42,160 Speaker 1: the kind we're made out of. But you're saying that 742 00:37:42,200 --> 00:37:45,240 Speaker 1: even though the regular matter it might admit this dark radiation, 743 00:37:45,560 --> 00:37:48,200 Speaker 1: how is that possible. It might be that our matter 744 00:37:48,480 --> 00:37:50,920 Speaker 1: can feel these sort of like new forces, just at 745 00:37:50,960 --> 00:37:53,440 Speaker 1: a very very low level. We don't know, and so 746 00:37:53,520 --> 00:37:55,480 Speaker 1: this is like, you know, one way to look for 747 00:37:55,560 --> 00:37:57,840 Speaker 1: it under the assumption that our kind of matter could 748 00:37:57,880 --> 00:38:00,239 Speaker 1: feel these dark forces, which is not something we know. 749 00:38:00,280 --> 00:38:02,000 Speaker 1: It's just sort of like a guess. We do this 750 00:38:02,080 --> 00:38:04,279 Speaker 1: in physics a lot. We're like, we don't know if 751 00:38:04,280 --> 00:38:06,479 Speaker 1: it's possible to see it this way, but let's check, 752 00:38:06,600 --> 00:38:09,360 Speaker 1: because if it does feel this force, if neutron stars 753 00:38:09,440 --> 00:38:12,239 Speaker 1: can make these dark photons, we would be able to 754 00:38:12,280 --> 00:38:15,160 Speaker 1: see that. I see neutron stars are so it's such 755 00:38:15,200 --> 00:38:17,320 Speaker 1: an extreme event when they crash into each other that 756 00:38:17,320 --> 00:38:21,120 Speaker 1: that's one possible, you know, crazy scenario where it might 757 00:38:21,200 --> 00:38:23,440 Speaker 1: make dark gradiations exactly. And it's a place where we 758 00:38:23,440 --> 00:38:26,920 Speaker 1: can make very very precise calculations about the gravitational waves 759 00:38:26,920 --> 00:38:29,960 Speaker 1: and compare them to very very detailed data. So it's 760 00:38:29,960 --> 00:38:33,200 Speaker 1: an opportunity to look for like very small deviations, you know, 761 00:38:33,320 --> 00:38:35,320 Speaker 1: things that the neutron stars are doing that we can't 762 00:38:35,360 --> 00:38:40,399 Speaker 1: otherwise explain that might be explainable through dark photons. I see, 763 00:38:40,480 --> 00:38:42,440 Speaker 1: all right, what are some other ways we could maybe 764 00:38:42,520 --> 00:38:45,160 Speaker 1: feel this dark force? All the most generic ways you 765 00:38:45,320 --> 00:38:47,800 Speaker 1: just use gravity the kind of tests that we did before, 766 00:38:47,960 --> 00:38:49,680 Speaker 1: But there are some other approaches to look for these 767 00:38:49,719 --> 00:38:53,160 Speaker 1: dark photons, hoping that there's some connection between our kind 768 00:38:53,160 --> 00:38:56,120 Speaker 1: of matter and the dark matter, Like hoping that somehow 769 00:38:56,200 --> 00:39:00,680 Speaker 1: maybe these dark photons can turn into normal photon very 770 00:39:00,800 --> 00:39:04,120 Speaker 1: very rarely, and then we could detect that what how 771 00:39:04,120 --> 00:39:06,600 Speaker 1: can a dark photon turn into a regular photon. It 772 00:39:06,640 --> 00:39:09,000 Speaker 1: turns out that if you have another kind of force 773 00:39:09,040 --> 00:39:11,319 Speaker 1: that's very similar to the photon, has sort of like 774 00:39:11,480 --> 00:39:15,560 Speaker 1: a similar mathematical structure, that these forces like to talk 775 00:39:15,600 --> 00:39:17,960 Speaker 1: to each other, that there's like it's very easy to 776 00:39:18,000 --> 00:39:20,960 Speaker 1: build a physics model in which another kind of photon 777 00:39:21,120 --> 00:39:25,640 Speaker 1: can turn into our photon wha like spontaneously or only 778 00:39:25,680 --> 00:39:29,040 Speaker 1: in like high energy completions or you know, moments where 779 00:39:29,040 --> 00:39:32,240 Speaker 1: you have kind of this a state of pure energy. 780 00:39:32,320 --> 00:39:34,799 Speaker 1: It would be spontaneous, and in order for that to happen, 781 00:39:34,840 --> 00:39:37,160 Speaker 1: they would have to be some kind of particle in 782 00:39:37,200 --> 00:39:41,280 Speaker 1: the universe that has both kinds of charges. So imagine 783 00:39:41,360 --> 00:39:44,839 Speaker 1: some new kind, very very rare dark matter that does 784 00:39:44,960 --> 00:39:48,160 Speaker 1: have electric charges and also has some new kind of 785 00:39:48,280 --> 00:39:51,839 Speaker 1: dark electric charge. That particle could effectively be like a 786 00:39:51,880 --> 00:39:56,040 Speaker 1: portal that connects our photons to these other photons, and 787 00:39:56,080 --> 00:39:58,759 Speaker 1: it might be that these particles never really exist in 788 00:39:58,800 --> 00:40:01,960 Speaker 1: the universe, the way like top corks almost never exist 789 00:40:02,000 --> 00:40:04,400 Speaker 1: in the universe on their own, but they're sort of 790 00:40:04,440 --> 00:40:07,000 Speaker 1: like on the list of possibilities. As long as it's 791 00:40:07,000 --> 00:40:10,759 Speaker 1: on the list of possibilities, then dark photons can use 792 00:40:10,800 --> 00:40:14,640 Speaker 1: that as a portal to become normal photons and vice versa. 793 00:40:14,760 --> 00:40:18,160 Speaker 1: This allows them to spontaneously turn from one into the other. Whoa, 794 00:40:18,320 --> 00:40:21,680 Speaker 1: So that wouldn't make dark matter not dark, right, It 795 00:40:21,680 --> 00:40:23,680 Speaker 1: would mean that you can sort of see them. It would, 796 00:40:23,680 --> 00:40:25,920 Speaker 1: but these particles again wouldn't actually have to exist in 797 00:40:25,960 --> 00:40:29,279 Speaker 1: the universe. So imagine now the dark sector is some 798 00:40:29,360 --> 00:40:31,840 Speaker 1: kind of particle that's actually out there, that most of 799 00:40:31,840 --> 00:40:33,920 Speaker 1: the dark matter is made out of this particle. And 800 00:40:33,960 --> 00:40:37,040 Speaker 1: then there's the possibility for this other particle that has 801 00:40:37,160 --> 00:40:40,239 Speaker 1: electric charges and dark charges, even though it's never really 802 00:40:40,239 --> 00:40:43,080 Speaker 1: out there in the universe, as long as the possibility 803 00:40:43,200 --> 00:40:46,360 Speaker 1: for it to exist is part of sort of nature's menu. 804 00:40:47,000 --> 00:40:50,879 Speaker 1: That possibility allows dark photons to turn into photons. It's 805 00:40:50,880 --> 00:40:54,759 Speaker 1: called kinetic mixing because we see it happening with regular matter, right, 806 00:40:54,840 --> 00:40:57,520 Speaker 1: Like our photons turned into other kinds of stuff all 807 00:40:57,560 --> 00:41:00,400 Speaker 1: the time, yes, exactly, Like photons turned into pairs of 808 00:41:00,480 --> 00:41:04,239 Speaker 1: particles electrons and positrons, and then those can turn into 809 00:41:04,320 --> 00:41:08,680 Speaker 1: z bosons, right because z's also interact with electrons impositron. 810 00:41:08,800 --> 00:41:11,520 Speaker 1: So even if there weren't a single electron or positron 811 00:41:11,560 --> 00:41:14,239 Speaker 1: in the universe, a photon could still turn into a 812 00:41:14,320 --> 00:41:17,080 Speaker 1: z boson. And in the same way, as long as 813 00:41:17,120 --> 00:41:20,319 Speaker 1: there's the possibility for some virtual particle that connects these 814 00:41:20,320 --> 00:41:23,480 Speaker 1: two forces to exist, then photons could turn into dark 815 00:41:23,480 --> 00:41:26,840 Speaker 1: photons and vice versa. And that's kind of our only 816 00:41:26,880 --> 00:41:29,799 Speaker 1: hope of seeing this dark force directly. That's the best 817 00:41:29,840 --> 00:41:32,960 Speaker 1: way to see these dark forces directly, exactly, And so 818 00:41:33,080 --> 00:41:35,440 Speaker 1: people have built really cool experiments to try to like 819 00:41:35,880 --> 00:41:38,560 Speaker 1: make this happen more often, try to like create the 820 00:41:38,640 --> 00:41:43,319 Speaker 1: scenarios that would help induce dark photons to spontaneously turn 821 00:41:43,400 --> 00:41:47,040 Speaker 1: into photons. They have these resonant cavities at Fermilab, for example, 822 00:41:47,160 --> 00:41:50,000 Speaker 1: that should enhance the rate of this happening. If you 823 00:41:50,120 --> 00:41:52,719 Speaker 1: like build something with the right shape and size, it 824 00:41:52,760 --> 00:41:56,319 Speaker 1: creates a situation where this kind of spontaneous transformation is 825 00:41:56,320 --> 00:41:58,759 Speaker 1: more likely to happen. And so they look for this 826 00:41:58,880 --> 00:42:02,360 Speaker 1: kind of signature. Wait, that's being built right now, Like 827 00:42:02,400 --> 00:42:06,480 Speaker 1: there are people building basically dark forest boxes. These things 828 00:42:06,520 --> 00:42:09,360 Speaker 1: exist already and they are being run and they're just 829 00:42:09,400 --> 00:42:11,080 Speaker 1: building them bigger and bigger. It's sort of like the 830 00:42:11,080 --> 00:42:13,000 Speaker 1: way people are looking for a dark matter. They look 831 00:42:13,040 --> 00:42:15,480 Speaker 1: in these containers underground, and they started with small ones, 832 00:42:15,480 --> 00:42:17,480 Speaker 1: and then they're making bigger and bigger and bigger ones. 833 00:42:17,719 --> 00:42:20,359 Speaker 1: Nobody's seeing a dark photon yet, but they're hoping as 834 00:42:20,360 --> 00:42:23,760 Speaker 1: they make these cavities more precise and larger to induce 835 00:42:23,800 --> 00:42:27,200 Speaker 1: a dark photon to turn into a normal photon. Cool, 836 00:42:27,360 --> 00:42:29,160 Speaker 1: and how else can you look for these? Another way 837 00:42:29,160 --> 00:42:32,000 Speaker 1: to look for these is to look for particles appearing 838 00:42:32,040 --> 00:42:34,480 Speaker 1: where they shouldn't be. So one of my favorite kind 839 00:42:34,480 --> 00:42:37,520 Speaker 1: of experiments, it's called a beam dump experiment, where you 840 00:42:37,560 --> 00:42:39,479 Speaker 1: take a particle beam you were using for something else 841 00:42:39,520 --> 00:42:41,480 Speaker 1: and you dump it, meaning you just like shoot it 842 00:42:41,480 --> 00:42:45,000 Speaker 1: into a huge block of concrete or into a mountain side, 843 00:42:45,280 --> 00:42:47,000 Speaker 1: just because you know, it's got to go somewhere. You 844 00:42:47,000 --> 00:42:50,080 Speaker 1: don't want to like sprayed over the neighborhood because it's dangerous, right, 845 00:42:50,120 --> 00:42:51,840 Speaker 1: just shoot it through the earth at people on the 846 00:42:51,880 --> 00:42:54,120 Speaker 1: other side of the earth. Is that what you're saying, Yeah, exactly. 847 00:42:54,520 --> 00:42:56,319 Speaker 1: And so Sho didn't do a mountain. It was on 848 00:42:56,360 --> 00:42:59,799 Speaker 1: the other side of Daniel. It's not California, is I'm 849 00:43:00,000 --> 00:43:02,480 Speaker 1: to have to look that up. But if you shoot 850 00:43:02,520 --> 00:43:05,239 Speaker 1: this particle beam into a mountain, for example, and then 851 00:43:05,280 --> 00:43:08,200 Speaker 1: you put a particle detector on the other side of 852 00:43:08,280 --> 00:43:10,919 Speaker 1: the mountain, none of the particles should make it through 853 00:43:10,920 --> 00:43:14,319 Speaker 1: the mountain, but you might see particles appearing in your 854 00:43:14,360 --> 00:43:16,920 Speaker 1: detector on the other side of the mountain, because dark 855 00:43:17,000 --> 00:43:19,960 Speaker 1: photons might make it through the mountain because they basically 856 00:43:20,000 --> 00:43:22,600 Speaker 1: see the mountain is invisible as transparent. The ideas if 857 00:43:22,640 --> 00:43:27,600 Speaker 1: your beam sometimes occasionally produces dark photons, those dark photons 858 00:43:27,600 --> 00:43:30,359 Speaker 1: would make it through the mountain. And so essentially it's 859 00:43:30,480 --> 00:43:33,520 Speaker 1: like looking for light shining through walls or I see 860 00:43:33,520 --> 00:43:35,359 Speaker 1: so many the ideas that you send this beam out 861 00:43:35,360 --> 00:43:38,520 Speaker 1: into the mountain, some of it turns into dark photons, 862 00:43:38,760 --> 00:43:42,040 Speaker 1: and then somehow it turns back into regular photons before 863 00:43:42,080 --> 00:43:44,640 Speaker 1: it hits your detector. Yeah, that's exactly right. And so 864 00:43:44,800 --> 00:43:48,399 Speaker 1: you're hoping that sometimes those dark photons turned back into 865 00:43:48,440 --> 00:43:51,040 Speaker 1: normal photons. So you're assuming a lot of things here. 866 00:43:51,080 --> 00:43:54,319 Speaker 1: You're assuming that maybe sometimes dark photons are created in 867 00:43:54,320 --> 00:43:57,640 Speaker 1: your beam, and that sometimes they turn back into normal photons. Right, 868 00:43:57,640 --> 00:43:59,799 Speaker 1: But if they turn back into regular photons, how would 869 00:43:59,840 --> 00:44:02,120 Speaker 1: you know they turned into dark photons in the middle. Yeah, 870 00:44:02,160 --> 00:44:04,160 Speaker 1: you wouldn't know for sure. You would just know that 871 00:44:04,440 --> 00:44:07,680 Speaker 1: something passed through the mountain that typically shouldn't be able to. 872 00:44:07,920 --> 00:44:10,839 Speaker 1: So you calculate, like how often should particles be able 873 00:44:10,840 --> 00:44:14,399 Speaker 1: to pass through the mountain and turn into photons? And 874 00:44:14,520 --> 00:44:17,319 Speaker 1: if that happens more often than you expect, then you 875 00:44:17,320 --> 00:44:20,040 Speaker 1: know there's something else and new there, maybe a dark photon, 876 00:44:20,120 --> 00:44:22,399 Speaker 1: maybe something else. But you know, that's often the case 877 00:44:22,440 --> 00:44:25,680 Speaker 1: with particle physics. We find something new, we're not exactly 878 00:44:25,719 --> 00:44:28,480 Speaker 1: sure what it is, and then we study it in detail, 879 00:44:28,520 --> 00:44:30,839 Speaker 1: we try to characterize exactly what it is, just like 880 00:44:31,040 --> 00:44:33,719 Speaker 1: with the Higgs boson. First thing, we saw some new 881 00:44:33,760 --> 00:44:36,960 Speaker 1: particle decaying into two photons, and we weren't sure is 882 00:44:37,000 --> 00:44:38,759 Speaker 1: this the Higgs boson or is it something else? We 883 00:44:38,760 --> 00:44:41,200 Speaker 1: didn't expect, and over decades of study we sort of 884 00:44:41,239 --> 00:44:43,160 Speaker 1: pinned down what it must be because of all of 885 00:44:43,200 --> 00:44:45,880 Speaker 1: its behaviors. I see, it's like, the only way it 886 00:44:45,880 --> 00:44:48,839 Speaker 1: could have made it through the mountain to and out 887 00:44:48,880 --> 00:44:51,760 Speaker 1: into California to hit us it was if it turned 888 00:44:51,760 --> 00:44:56,520 Speaker 1: into something invisible like dark photons somewhere in the middle. 889 00:44:56,760 --> 00:44:58,719 Speaker 1: Otherwise it wouldn't have made it through. Exactly, I have 890 00:44:58,840 --> 00:45:01,120 Speaker 1: to phase through the mountain by turning into something that 891 00:45:01,160 --> 00:45:04,040 Speaker 1: doesn't interact with mountains. All right, cool, Well, what are 892 00:45:04,120 --> 00:45:05,800 Speaker 1: some other ways we might be able to see these 893 00:45:05,880 --> 00:45:08,400 Speaker 1: dark forces? A lot of the other experiments are very similar. 894 00:45:08,680 --> 00:45:13,279 Speaker 1: There's one at CERN called Phaser Forward Search Experiment. It's 895 00:45:13,320 --> 00:45:16,520 Speaker 1: a pretty tortured acronym, but a really cool idea for 896 00:45:17,480 --> 00:45:19,720 Speaker 1: I don't even know what is there an A actually 897 00:45:19,760 --> 00:45:23,080 Speaker 1: in the name, there's an A and forward and an 898 00:45:23,239 --> 00:45:27,760 Speaker 1: R experiment. Oh man, it's a really cool idea because 899 00:45:27,800 --> 00:45:31,400 Speaker 1: they're taking an already existing experiment Atlas where we collide 900 00:45:31,400 --> 00:45:35,040 Speaker 1: protons together and they're wondering like maybe dark photons are 901 00:45:35,040 --> 00:45:37,680 Speaker 1: created and shoot down the beam. So they built a 902 00:45:37,719 --> 00:45:41,160 Speaker 1: detector like really far down along the beam past where 903 00:45:41,160 --> 00:45:44,000 Speaker 1: the collisions happen to see if maybe dark photons are 904 00:45:44,040 --> 00:45:47,040 Speaker 1: created in those collisions and then fly along the beam 905 00:45:47,160 --> 00:45:49,680 Speaker 1: and then turn into something that they can see sort 906 00:45:49,680 --> 00:45:53,319 Speaker 1: of downstream. So they added this little bit to the 907 00:45:53,360 --> 00:45:55,960 Speaker 1: detector that can do something totally novel and new. It's 908 00:45:55,960 --> 00:45:58,240 Speaker 1: actually led by a team here at you see Irvine, 909 00:45:58,360 --> 00:46:00,480 Speaker 1: m M, I see. But we don't actually know if 910 00:46:00,560 --> 00:46:03,440 Speaker 1: dark matter can switch back and forth that easily, right, 911 00:46:03,640 --> 00:46:05,640 Speaker 1: We don't know. And again, it could be that dark 912 00:46:05,640 --> 00:46:09,160 Speaker 1: matter is only some inert particle that feels gravity and 913 00:46:09,200 --> 00:46:11,319 Speaker 1: nothing else and there are no dark forces and no 914 00:46:11,440 --> 00:46:14,360 Speaker 1: way to interact. It could also be that dark matter 915 00:46:14,480 --> 00:46:17,640 Speaker 1: does feel some new dark force, but can only interact 916 00:46:17,680 --> 00:46:20,359 Speaker 1: with itself, and none of those dark forces can ever 917 00:46:20,520 --> 00:46:24,480 Speaker 1: turn into normal matter or normal photons. Here, we're just guessing. 918 00:46:24,480 --> 00:46:27,640 Speaker 1: We're trying to like study the various possibilities in the 919 00:46:27,719 --> 00:46:32,080 Speaker 1: various ways that those possibilities might manifesto well, And so 920 00:46:32,160 --> 00:46:33,960 Speaker 1: what does it all mean? Do you think we will 921 00:46:34,000 --> 00:46:37,399 Speaker 1: find it has interactions with itself or do you think 922 00:46:37,440 --> 00:46:40,279 Speaker 1: it just represents this whole part of the universe that 923 00:46:40,320 --> 00:46:42,759 Speaker 1: we will never be able to see or touch or 924 00:46:42,800 --> 00:46:45,319 Speaker 1: even confirm that it's there. You know, like we could 925 00:46:45,320 --> 00:46:50,120 Speaker 1: be swimming in dark rubber duckies and never ever ever, Yeah, 926 00:46:50,239 --> 00:46:52,120 Speaker 1: part of it comes down to what you think is 927 00:46:52,160 --> 00:46:54,440 Speaker 1: more natural. Does it make sense to you to have 928 00:46:54,560 --> 00:46:57,920 Speaker 1: a huge component of the universe be sort of simple 929 00:46:58,160 --> 00:47:00,960 Speaker 1: and inert and not really doing any being interesting, or 930 00:47:01,000 --> 00:47:03,680 Speaker 1: does this seem more natural for it to be complex 931 00:47:03,680 --> 00:47:06,680 Speaker 1: and interactive the way that our matter is. Now, what 932 00:47:06,800 --> 00:47:09,239 Speaker 1: I know is that the universe doesn't follow what we 933 00:47:09,360 --> 00:47:12,600 Speaker 1: think is natural. Our conceptions of how the universe should 934 00:47:12,640 --> 00:47:14,680 Speaker 1: work don't seem to be very well aligned with how 935 00:47:14,719 --> 00:47:17,440 Speaker 1: it usually does work, and so I suspect there are 936 00:47:17,480 --> 00:47:19,880 Speaker 1: some surprises out there. The other side of that question 937 00:47:19,960 --> 00:47:22,120 Speaker 1: is what you asked, is might we ever be able 938 00:47:22,160 --> 00:47:24,160 Speaker 1: to tell? And it could be that dark matter doesn't 939 00:47:24,160 --> 00:47:26,240 Speaker 1: feel any of our forces, and none of these forces 940 00:47:26,239 --> 00:47:28,560 Speaker 1: can talk to our forces, and we can never find 941 00:47:28,719 --> 00:47:31,840 Speaker 1: these dark rubber duckies. But I have faith in physicists 942 00:47:31,880 --> 00:47:34,640 Speaker 1: and engineers to come up with clever ways to probe 943 00:47:34,680 --> 00:47:37,799 Speaker 1: these things, ways that we can't even today. Imagine kinds 944 00:47:37,840 --> 00:47:40,439 Speaker 1: of experiments that people might think of in ten years 945 00:47:40,520 --> 00:47:43,200 Speaker 1: or twenty years, experiments thought up by you know, clever 946 00:47:43,320 --> 00:47:46,560 Speaker 1: Listeners to this podcast who aren't constrained by the kind 947 00:47:46,560 --> 00:47:49,359 Speaker 1: of thinking that academic physicists have been trained to do. 948 00:47:49,560 --> 00:47:51,120 Speaker 1: I think I know how you can do it, Daniel, 949 00:47:51,239 --> 00:47:54,960 Speaker 1: Dark Chocolate collisions. You just gotta want it enough. You know, 950 00:47:55,320 --> 00:47:58,360 Speaker 1: you have to really want it, because, as Yoda says, 951 00:47:58,400 --> 00:48:01,960 Speaker 1: you know, wanting these to pain and pain needs to suffering, 952 00:48:02,680 --> 00:48:05,359 Speaker 1: and suffering leads to the dark side, and so that's 953 00:48:05,360 --> 00:48:07,560 Speaker 1: that's how you can get there faster. Maybe, Yeah, there 954 00:48:07,640 --> 00:48:09,640 Speaker 1: is no try. I should just do it, that's right, 955 00:48:09,719 --> 00:48:15,120 Speaker 1: Just I mean, do it? You should, yes, all right. 956 00:48:15,160 --> 00:48:16,439 Speaker 1: I don't know why I didn't think of that before. 957 00:48:16,480 --> 00:48:18,040 Speaker 1: I'm just gonna go do it right after we're done 958 00:48:18,080 --> 00:48:20,239 Speaker 1: with this podcast, or not do it. I guess we're 959 00:48:20,239 --> 00:48:23,040 Speaker 1: doing in the dark. Gosh, I'm so confused. But to me, 960 00:48:23,080 --> 00:48:25,840 Speaker 1: it really touches on these deep mysteries of physics that 961 00:48:25,960 --> 00:48:28,520 Speaker 1: we know the universe out there is telling stories that 962 00:48:28,560 --> 00:48:31,200 Speaker 1: we haven't heard yet. We're desperate to hear those stories. 963 00:48:31,480 --> 00:48:33,760 Speaker 1: We have hints that we know the shape of those stories, 964 00:48:33,760 --> 00:48:35,759 Speaker 1: but we don't know any of the details yet, and 965 00:48:35,840 --> 00:48:37,480 Speaker 1: I just hope that one day we'll be able to 966 00:48:37,520 --> 00:48:39,839 Speaker 1: fill those in. Yeah, it's almost like there's a whole 967 00:48:39,960 --> 00:48:42,440 Speaker 1: universe out there, sitting right in front of us that 968 00:48:42,520 --> 00:48:45,480 Speaker 1: we have yet to discover, and that anyone listening to 969 00:48:45,520 --> 00:48:47,840 Speaker 1: this could become part of that search. That's right. So 970 00:48:47,880 --> 00:48:50,560 Speaker 1: there's plenty more of the universe to find out, and 971 00:48:50,560 --> 00:48:54,120 Speaker 1: we desperately need new ideas. And whether the universe counts 972 00:48:54,120 --> 00:48:56,960 Speaker 1: as dark chocolate or not, that's for other people to debate. 973 00:48:57,719 --> 00:49:00,440 Speaker 1: That's right. And if you love white chocolate, take my apologies. 974 00:49:00,480 --> 00:49:03,440 Speaker 1: I love all of them. You love listeners more than 975 00:49:03,480 --> 00:49:07,239 Speaker 1: you love your chocolate, exactly, And if you eat white 976 00:49:07,280 --> 00:49:11,000 Speaker 1: chocolate while listen to this podcast, I forgive you because 977 00:49:11,120 --> 00:49:13,440 Speaker 1: he can't see your or feel you, so it doesn't 978 00:49:13,440 --> 00:49:17,799 Speaker 1: matter to exactly. Please accept my dark apologies. All right, Well, 979 00:49:17,840 --> 00:49:20,239 Speaker 1: we hope you enjoyed that. Thanks for joining us, See 980 00:49:20,239 --> 00:49:30,680 Speaker 1: you next time. Thanks for listening, and remember that Daniel 981 00:49:30,719 --> 00:49:33,239 Speaker 1: and Jorge Explain the Universe is a production of I 982 00:49:33,480 --> 00:49:36,919 Speaker 1: Heart Radio. For more podcast for my heart Radio, visit 983 00:49:36,920 --> 00:49:40,440 Speaker 1: the I heart Radio app, Apple Podcasts, or wherever you 984 00:49:40,520 --> 00:49:47,799 Speaker 1: listen to your favorite shows. Yeah,