1 00:00:08,800 --> 00:00:12,080 Speaker 1: Jorge, I have an idea for our Daniel and Jorge 2 00:00:12,119 --> 00:00:15,320 Speaker 1: explain the universe food truck. Oh nice, wait, are reactually 3 00:00:15,360 --> 00:00:16,920 Speaker 1: doing that? I thought it was a joke. Well, it 4 00:00:17,000 --> 00:00:19,720 Speaker 1: was a joke, but then our listener Tim Lazarov road 5 00:00:19,760 --> 00:00:21,880 Speaker 1: in to ask when our food truck is going to 6 00:00:21,960 --> 00:00:24,319 Speaker 1: be in his neighborhood. May should be more like a 7 00:00:24,400 --> 00:00:27,120 Speaker 1: food spaceship it would be more appropriate. Well, that goes 8 00:00:27,280 --> 00:00:30,920 Speaker 1: perfectly well with my idea. You see, normal food trucks 9 00:00:31,080 --> 00:00:34,120 Speaker 1: sort of drinks right fluids to wash down their taste treats. 10 00:00:34,880 --> 00:00:39,400 Speaker 1: But our food spaceship should serve super fluids like zero 11 00:00:39,560 --> 00:00:43,280 Speaker 1: viscosity beverages nice, so they go down easier. Or do 12 00:00:43,320 --> 00:00:47,280 Speaker 1: they have Bose Einstein condensation on the outside. I'm thinking 13 00:00:47,320 --> 00:00:49,479 Speaker 1: we should test it on some undergrads, you know, make 14 00:00:49,479 --> 00:00:51,200 Speaker 1: sure it's safe before we sell it to the public. 15 00:00:51,200 --> 00:00:53,199 Speaker 1: I'm sure the FDA is all over that. I don't 16 00:00:53,240 --> 00:00:55,760 Speaker 1: think they have a physics food division yet. That's the 17 00:00:55,840 --> 00:01:14,680 Speaker 1: p d A Physics and Drugs Administration. Hi, I'm or 18 00:01:14,720 --> 00:01:16,760 Speaker 1: hand me a a cartoonists and the co author of Frequently 19 00:01:16,800 --> 00:01:20,160 Speaker 1: Asked Questions about the Universe. Hi I'm Daniel. I'm a 20 00:01:20,200 --> 00:01:24,000 Speaker 1: physics professor and a particle physicist who does research at CERN. 21 00:01:24,319 --> 00:01:26,560 Speaker 1: And every time I'm in a lab, I'm always tempted 22 00:01:26,640 --> 00:01:31,480 Speaker 1: to taste everything that sounds like a terrible Daniel, especially 23 00:01:31,560 --> 00:01:34,480 Speaker 1: if you visit a virology lab. Yeah, but you know 24 00:01:34,520 --> 00:01:37,039 Speaker 1: they got like weird glowing goo. You're like, m I 25 00:01:37,120 --> 00:01:40,000 Speaker 1: wonder what flavor that is. I'm never gonna do it, 26 00:01:40,080 --> 00:01:44,240 Speaker 1: of course, I hope, but you know, the curious mind wonders, right, 27 00:01:44,280 --> 00:01:46,720 Speaker 1: Remind me never to invite you to my lab, otherwise 28 00:01:46,760 --> 00:01:50,600 Speaker 1: you'll be licking everything like a dog or a two 29 00:01:50,680 --> 00:01:52,560 Speaker 1: year old, like that kid in the movie that licks 30 00:01:52,560 --> 00:01:54,920 Speaker 1: the flagpole and wonders if his tongue is really going 31 00:01:55,000 --> 00:01:57,440 Speaker 1: to stick to it. We should get into the physics 32 00:01:57,520 --> 00:02:01,720 Speaker 1: of a Christmas story will shoot your eyes out. But 33 00:02:01,800 --> 00:02:04,520 Speaker 1: welcome to our podcast Daniel and Jorge Explain the Universe, 34 00:02:04,600 --> 00:02:07,080 Speaker 1: a production of I Heart Radio in which we invite 35 00:02:07,120 --> 00:02:10,919 Speaker 1: you to taste the entire universe to enjoy the flavor 36 00:02:10,960 --> 00:02:14,240 Speaker 1: of knowledge as well as ignorance, to take a bite 37 00:02:14,240 --> 00:02:16,760 Speaker 1: out of everything that we do and do not know 38 00:02:16,919 --> 00:02:20,360 Speaker 1: about the universe. We don't shy away from the big mysteries. 39 00:02:20,400 --> 00:02:22,720 Speaker 1: On this podcast. We talk about the smallest things, the 40 00:02:22,840 --> 00:02:26,160 Speaker 1: medium sized things, and even the biggest things, and we 41 00:02:26,240 --> 00:02:29,359 Speaker 1: attack all of them and try to explain them to you. Yeah, 42 00:02:29,400 --> 00:02:32,680 Speaker 1: it is a delicious looking universe, like a giant cosmic 43 00:02:32,720 --> 00:02:36,400 Speaker 1: bouffet of amazing ideas and incredible phenomena that are there 44 00:02:36,480 --> 00:02:40,040 Speaker 1: for us to dig into and fill our bellies with 45 00:02:40,160 --> 00:02:42,919 Speaker 1: amazing knowledge. Yeah. And if you're not a curious person, 46 00:02:43,000 --> 00:02:45,200 Speaker 1: then you wouldn't take a bite to these weird things. 47 00:02:45,240 --> 00:02:47,440 Speaker 1: And I think that's why when I'm in some kind 48 00:02:47,440 --> 00:02:49,799 Speaker 1: of laboratory and I see something weird bubbling in a 49 00:02:49,840 --> 00:02:52,120 Speaker 1: flask and I wonder, I wonder if that would make 50 00:02:52,120 --> 00:02:54,960 Speaker 1: a good soda for our food truck, It's that same 51 00:02:55,040 --> 00:02:57,600 Speaker 1: curiosity that inspires me to try to take a bite 52 00:02:57,600 --> 00:03:00,160 Speaker 1: out of the whole universe because I want to know. 53 00:03:00,280 --> 00:03:02,800 Speaker 1: I want to understand. It's not enough to just say 54 00:03:02,919 --> 00:03:05,880 Speaker 1: I bet that green bubbling thing tastes something like lemon 55 00:03:05,919 --> 00:03:08,679 Speaker 1: lime soda. I want to actually know the truth. I 56 00:03:08,720 --> 00:03:11,200 Speaker 1: think there are easier ways to find out what something is, Daniel, 57 00:03:11,280 --> 00:03:14,000 Speaker 1: rather than bringing it in your mouth and in your body, 58 00:03:14,120 --> 00:03:16,600 Speaker 1: Have you tried asking what it is? It seems like 59 00:03:16,639 --> 00:03:18,360 Speaker 1: the polite thing to do. But then how would they know, 60 00:03:18,560 --> 00:03:21,000 Speaker 1: right if they haven't tasted it. Maybe some questions are 61 00:03:21,000 --> 00:03:23,480 Speaker 1: not meant to be answered, What like, are you curious 62 00:03:23,480 --> 00:03:27,040 Speaker 1: about how sanide tastes? I am curious? Actually, you know, 63 00:03:27,080 --> 00:03:29,560 Speaker 1: I like almond pastries and so hey, maybe you know 64 00:03:29,600 --> 00:03:32,000 Speaker 1: a nice cyanide after flavor is not the worst thing 65 00:03:32,040 --> 00:03:34,080 Speaker 1: in the world. But yeah, I'm curious about all this stuff, 66 00:03:34,120 --> 00:03:36,400 Speaker 1: even the stuff that might kill you to find out 67 00:03:36,440 --> 00:03:40,200 Speaker 1: the answer. It's just this deep desire to know these truths. Well, 68 00:03:40,240 --> 00:03:44,680 Speaker 1: speaking of dark matters like tasting poison, there are amazing 69 00:03:44,720 --> 00:03:47,280 Speaker 1: mysteries out there, including one that is maybe one of 70 00:03:47,320 --> 00:03:49,280 Speaker 1: the biggest mysteries in the universe. At least it's the 71 00:03:49,280 --> 00:03:52,360 Speaker 1: second biggest mystery in the universe by percentage. Boys, right, 72 00:03:52,440 --> 00:03:54,480 Speaker 1: that's right. If the universe was laid out as a buffet, 73 00:03:54,560 --> 00:03:56,920 Speaker 1: most of it would be dark energy, but a huge, 74 00:03:57,200 --> 00:04:01,280 Speaker 1: heaping pile of it would be dark arc matter. Most 75 00:04:01,360 --> 00:04:05,200 Speaker 1: of the actual stuff in the universe, the matter, the things, 76 00:04:05,520 --> 00:04:08,520 Speaker 1: the bits and pieces that move around in our universe, 77 00:04:08,720 --> 00:04:11,120 Speaker 1: are not the things that make up me and you 78 00:04:11,520 --> 00:04:15,800 Speaker 1: and weird beakers of bubbling green goo in chemistry laboratories, 79 00:04:16,040 --> 00:04:19,719 Speaker 1: it's something else, something different, something we do not yet understand, 80 00:04:20,040 --> 00:04:21,920 Speaker 1: but we have a cool name for it. That's right, 81 00:04:21,920 --> 00:04:23,719 Speaker 1: we have a cool name for it. It's dark matter. 82 00:04:23,839 --> 00:04:26,320 Speaker 1: And that is an interesting analogy, Daniel. I guess the 83 00:04:26,400 --> 00:04:29,240 Speaker 1: universe is like a giant buffet, and five percent of 84 00:04:29,240 --> 00:04:33,360 Speaker 1: it is like regular food, right, chicken and bread and 85 00:04:33,560 --> 00:04:37,200 Speaker 1: pasta slad, And about twenty seven percent of that buffet 86 00:04:37,520 --> 00:04:41,920 Speaker 1: is a big giant mystery, some kind of weird dark stuff. 87 00:04:41,960 --> 00:04:44,719 Speaker 1: And I guess you would be right in there tiling 88 00:04:44,760 --> 00:04:46,280 Speaker 1: it on on your plate. Yeah, I don't know if 89 00:04:46,279 --> 00:04:47,800 Speaker 1: I'll go back for seconds. You know, I got to 90 00:04:47,839 --> 00:04:50,240 Speaker 1: try the first serving, but yes, serve me up some 91 00:04:50,360 --> 00:04:52,400 Speaker 1: dark matter. I want to know what it is. Does 92 00:04:52,440 --> 00:04:55,360 Speaker 1: it in the end just taste like chicken? Would it taste? 93 00:04:55,360 --> 00:04:57,680 Speaker 1: I guess it would just go through your tongue, wouldn't it. 94 00:04:57,839 --> 00:05:01,640 Speaker 1: That's right. Dark matter sounds like something black and heavy, 95 00:05:02,080 --> 00:05:06,800 Speaker 1: but actually it's invisible and intangible. Dark matter would pass 96 00:05:07,040 --> 00:05:10,120 Speaker 1: right through you like a cloud of neutrinos, because we 97 00:05:10,160 --> 00:05:12,640 Speaker 1: don't think that it interacts with normal matter in any 98 00:05:12,680 --> 00:05:15,920 Speaker 1: way other than with gravity, and gravity is a very 99 00:05:16,040 --> 00:05:18,760 Speaker 1: very weak force, so you couldn't even like pick up 100 00:05:18,800 --> 00:05:21,360 Speaker 1: a spoon of dark matter. You had like a blob 101 00:05:21,400 --> 00:05:23,679 Speaker 1: of dark matter, and you dropped it, it would fall 102 00:05:23,760 --> 00:05:26,159 Speaker 1: to the center of the Earth, right, And we don't 103 00:05:26,200 --> 00:05:28,120 Speaker 1: even know if it is matter. We don't even know 104 00:05:28,160 --> 00:05:30,400 Speaker 1: if it is stuff. All we know about it is 105 00:05:30,440 --> 00:05:33,120 Speaker 1: its effect on the rest of the universe and the 106 00:05:33,120 --> 00:05:35,240 Speaker 1: rest of the stars and galaxies out there that we 107 00:05:35,240 --> 00:05:38,120 Speaker 1: can see. That's right. We have never confirmed the particle 108 00:05:38,200 --> 00:05:40,640 Speaker 1: nature of dark matter. We don't even really know a 109 00:05:40,720 --> 00:05:42,960 Speaker 1: hundred percent that it's stuff. And we've talked about it 110 00:05:43,000 --> 00:05:44,840 Speaker 1: on the podcast a lot of times and we've said 111 00:05:44,839 --> 00:05:47,520 Speaker 1: that we are pretty sure it's matter, but there are 112 00:05:47,560 --> 00:05:49,800 Speaker 1: some questions that remain. There are some things that we 113 00:05:49,880 --> 00:05:52,159 Speaker 1: see out there in the universe that the idea that 114 00:05:52,240 --> 00:05:55,240 Speaker 1: dark matter is stuff is some kind of invisible new 115 00:05:55,360 --> 00:05:59,320 Speaker 1: matter in the universe doesn't quite explain. And there are 116 00:05:59,360 --> 00:06:02,159 Speaker 1: a few other our ideas, different hypotheses to try to 117 00:06:02,200 --> 00:06:03,839 Speaker 1: explain it. And I know that it's one of the 118 00:06:03,880 --> 00:06:06,560 Speaker 1: favorite pastime of our listeners because they're always writing the 119 00:06:06,600 --> 00:06:09,520 Speaker 1: emails about maybe dark matter is actually this other thing, 120 00:06:09,640 --> 00:06:11,560 Speaker 1: or what if dark matter it could be something else 121 00:06:11,600 --> 00:06:14,560 Speaker 1: totally different. It is one of the biggest most accessible 122 00:06:14,640 --> 00:06:17,960 Speaker 1: mysteries in the universe. That's right. Maybe it is a 123 00:06:18,000 --> 00:06:21,560 Speaker 1: giant tree of some kind of cosmic buffet for some 124 00:06:21,600 --> 00:06:25,719 Speaker 1: giant beings. Perhaps. Yeah, maybe it's just like weird pasta 125 00:06:25,839 --> 00:06:28,360 Speaker 1: instead of squidding, because they put something else into it 126 00:06:28,440 --> 00:06:31,400 Speaker 1: to make it like really dark or invisible. But I 127 00:06:31,440 --> 00:06:33,360 Speaker 1: guess what you mean, right, Yeah, if there's some kind 128 00:06:33,360 --> 00:06:36,119 Speaker 1: of animal, let's bray something that makes it invisible, maybe 129 00:06:36,120 --> 00:06:38,560 Speaker 1: they've just inserted that into the dark matter pasta. Well, 130 00:06:38,600 --> 00:06:40,760 Speaker 1: hopefully it's more like the dessert of the universe, because 131 00:06:40,760 --> 00:06:42,720 Speaker 1: that would be pretty neat, right. A third of the 132 00:06:42,800 --> 00:06:46,280 Speaker 1: universe is just desserts. Does that tell us about your diet? 133 00:06:46,400 --> 00:06:50,120 Speaker 1: Or Hey, are you like desserts? Sure? Why not? I 134 00:06:50,160 --> 00:06:55,920 Speaker 1: guess it all depends on your perspective. Vegetables can't be dessert, right, sure, yeah, 135 00:06:55,960 --> 00:06:58,640 Speaker 1: I guess so I like a nice zucchini bread. Yeah, which, 136 00:06:58,720 --> 00:07:01,040 Speaker 1: it's that's technically what whread you eat at the end? Right, 137 00:07:01,320 --> 00:07:03,840 Speaker 1: sounds good. Well, I'm hoping that we can gobble of 138 00:07:03,960 --> 00:07:06,440 Speaker 1: the mystery of dark matter one day, but until then, 139 00:07:06,800 --> 00:07:09,000 Speaker 1: we have to think carefully about what we have seen, 140 00:07:09,279 --> 00:07:11,800 Speaker 1: what we know, what we can explain, what we can't 141 00:07:11,840 --> 00:07:15,000 Speaker 1: explain and what new ideas we might need to tell 142 00:07:15,000 --> 00:07:18,160 Speaker 1: a complete and true story about everything that's happening out 143 00:07:18,160 --> 00:07:20,800 Speaker 1: there in the universe. Yeah, it is an ongoing debate 144 00:07:20,840 --> 00:07:23,760 Speaker 1: about what dark matter is, and it's an ongoing exploration 145 00:07:23,800 --> 00:07:25,800 Speaker 1: of what it could be. So today we'll be talking 146 00:07:25,840 --> 00:07:29,080 Speaker 1: about one possible idea for dark matter. So today on 147 00:07:29,120 --> 00:07:36,760 Speaker 1: the program, we'll be tackling the question could dark matter 148 00:07:37,160 --> 00:07:41,280 Speaker 1: be a super fluid? And if so, is it's sparkling? 149 00:07:41,640 --> 00:07:43,680 Speaker 1: And will it kill you? I guess if you drink 150 00:07:43,720 --> 00:07:46,120 Speaker 1: it question number two? Right, First, I want to know 151 00:07:46,160 --> 00:07:48,960 Speaker 1: if it's carbonated, and then question number two is can 152 00:07:49,000 --> 00:07:51,720 Speaker 1: I survive drinking it? Well, it dissolve all the carbon 153 00:07:51,800 --> 00:07:54,520 Speaker 1: in your body is the second question. I guess you 154 00:07:54,560 --> 00:07:57,160 Speaker 1: would want to know before you drink anything, unless you're 155 00:07:57,240 --> 00:07:59,800 Speaker 1: Daniel whites It. Yeah, and it's a really interesting question. 156 00:08:00,000 --> 00:08:02,200 Speaker 1: Other dark matter is a super fluid, and you might 157 00:08:02,240 --> 00:08:04,200 Speaker 1: wonder like, why do we care? Why do we think 158 00:08:04,280 --> 00:08:06,600 Speaker 1: it might be a super fluid. And for all the 159 00:08:06,680 --> 00:08:10,119 Speaker 1: successes that dark matter has had in explaining the large 160 00:08:10,120 --> 00:08:13,440 Speaker 1: scale structure of the universe and gravitational lensing and the 161 00:08:13,480 --> 00:08:16,880 Speaker 1: wiggles we see in the cosmic microwave background radiation. We'll 162 00:08:16,880 --> 00:08:18,320 Speaker 1: talk about it in a minute, But there are some 163 00:08:18,400 --> 00:08:21,400 Speaker 1: things that dark matter as a theory of some weird 164 00:08:21,440 --> 00:08:25,240 Speaker 1: invisible particle really struggles to explain in our universe. It 165 00:08:25,280 --> 00:08:27,120 Speaker 1: needs a little bit of help. Yeah, and I feel 166 00:08:27,120 --> 00:08:28,960 Speaker 1: like we maye skipped the question here, Like I feel 167 00:08:28,960 --> 00:08:31,240 Speaker 1: like we never even tackled the question could dark matter 168 00:08:31,280 --> 00:08:33,840 Speaker 1: be a fluid? Like do we even know if it 169 00:08:33,840 --> 00:08:36,440 Speaker 1: could be a fluid or a solid or gas? You will, Actually, 170 00:08:36,480 --> 00:08:40,160 Speaker 1: dark matter already we think is kind of a collisionless fluid, 171 00:08:40,480 --> 00:08:42,440 Speaker 1: sort of like an ideal gas. You know, we think 172 00:08:42,480 --> 00:08:44,680 Speaker 1: about it as these particles flying around in the universe, 173 00:08:44,920 --> 00:08:48,000 Speaker 1: not interacting with each other at all, because again, the 174 00:08:48,000 --> 00:08:51,240 Speaker 1: only interactions we think it has is gravity, and gravity 175 00:08:51,240 --> 00:08:54,240 Speaker 1: between particles is basically zero. So already we think of 176 00:08:54,320 --> 00:08:56,840 Speaker 1: dark matter sort of like a collisionless fluid or an 177 00:08:56,880 --> 00:08:59,240 Speaker 1: ideal gas. So here we're talking about it having like 178 00:08:59,320 --> 00:09:03,480 Speaker 1: special produced from being a super fluid like a superhero. 179 00:09:03,960 --> 00:09:06,959 Speaker 1: But shouldn't be like a super gas then? Yeah, exactly, 180 00:09:07,000 --> 00:09:09,280 Speaker 1: Maybe it gets bitten by a radioactive spider and then 181 00:09:09,320 --> 00:09:12,200 Speaker 1: turns into a super fluid or super gas. Yea radioactive 182 00:09:12,280 --> 00:09:14,520 Speaker 1: fluid spider, I guess it would have to be the 183 00:09:14,559 --> 00:09:17,040 Speaker 1: marvel theory of the universe. Well, as usually, we were 184 00:09:17,080 --> 00:09:19,960 Speaker 1: wondering how many people out there had considered this question 185 00:09:19,960 --> 00:09:23,320 Speaker 1: whether dark matter could be a super fluid. So Daniel 186 00:09:23,320 --> 00:09:25,760 Speaker 1: went out there into the wilds of the internet, or 187 00:09:25,800 --> 00:09:28,640 Speaker 1: maybe the campus of UC Irvine, which one this time? Daniel, 188 00:09:28,760 --> 00:09:32,080 Speaker 1: these are Internet answers, So thanks very much to everybody 189 00:09:32,080 --> 00:09:35,040 Speaker 1: who participates in these and waits patiently for us to 190 00:09:35,120 --> 00:09:37,520 Speaker 1: get to the episode. If you'd like to participate for 191 00:09:37,679 --> 00:09:40,320 Speaker 1: future episodes, please don't be shy right to us. Two 192 00:09:40,440 --> 00:09:43,480 Speaker 1: questions at Daniel and Jorge dot com. So think about 193 00:09:43,480 --> 00:09:46,280 Speaker 1: it for a second. Do you think dark matter could 194 00:09:46,360 --> 00:09:50,040 Speaker 1: be a super fluid? Here's what people had to say. Well, 195 00:09:50,080 --> 00:09:52,000 Speaker 1: I wish I knew what a super fluid was, because 196 00:09:52,240 --> 00:09:54,319 Speaker 1: that sounds like a really awesome thing to get to know. 197 00:09:54,840 --> 00:09:57,240 Speaker 1: The dark matter could be a lot of different things 198 00:09:57,400 --> 00:10:00,599 Speaker 1: still at this point, um, so sure it could be 199 00:10:00,600 --> 00:10:02,560 Speaker 1: a super fluid. It could be a great soft drink 200 00:10:03,240 --> 00:10:06,320 Speaker 1: that sadly just passes right through your body. I don't 201 00:10:06,360 --> 00:10:10,160 Speaker 1: really think that's true because the other superfluids that we've 202 00:10:10,240 --> 00:10:12,800 Speaker 1: created are all made out of hawks, they're just in 203 00:10:12,800 --> 00:10:15,800 Speaker 1: a different arrangement, and I don't think quarks can, you know, 204 00:10:16,040 --> 00:10:19,600 Speaker 1: display the behaviors that dark matter does. So no, I 205 00:10:19,600 --> 00:10:21,920 Speaker 1: don't think that dark matter is a super fluid, but 206 00:10:22,520 --> 00:10:25,959 Speaker 1: who knows, well, what's a super fluid. I believe that's 207 00:10:25,960 --> 00:10:29,240 Speaker 1: material that doesn't lose energy when it's moving, So it 208 00:10:29,320 --> 00:10:31,800 Speaker 1: sounds like document that would really hit that point because 209 00:10:31,800 --> 00:10:34,319 Speaker 1: it doesn't even inter fear with itself. On the other hand, 210 00:10:34,360 --> 00:10:36,880 Speaker 1: we know that doc meto is impacted by gravity, so 211 00:10:36,960 --> 00:10:39,120 Speaker 1: that would speak against it. So I'm not really sure. 212 00:10:39,280 --> 00:10:40,679 Speaker 1: But if I would have to make a bed, I 213 00:10:40,679 --> 00:10:43,520 Speaker 1: would say, yeah, it's a super fluid. I don't see 214 00:10:43,559 --> 00:10:47,720 Speaker 1: how can anything out in space be considered a fluid 215 00:10:48,280 --> 00:10:51,640 Speaker 1: given how low density it is, and if it isn't 216 00:10:51,640 --> 00:10:54,480 Speaker 1: a fluid, it could be a super fluid. No idea. 217 00:10:55,080 --> 00:10:58,400 Speaker 1: That's fascinating. I would not have thought dark matter was 218 00:10:58,440 --> 00:11:00,319 Speaker 1: dense enough to be a fluid in the sense that 219 00:11:00,360 --> 00:11:03,760 Speaker 1: we understand it. Um my understanding that dart matter is 220 00:11:03,760 --> 00:11:07,840 Speaker 1: going to be as diffuse as regular matter and its 221 00:11:07,840 --> 00:11:12,000 Speaker 1: distribution through a nearly infinite universe, so that it's going 222 00:11:12,040 --> 00:11:14,360 Speaker 1: to behave like a guess. I would think if I 223 00:11:14,360 --> 00:11:17,800 Speaker 1: remember correctly, a super fluid doesn't as a fluid fluid 224 00:11:17,840 --> 00:11:22,240 Speaker 1: without viscosity. I think it was viscosity. And well, we 225 00:11:22,360 --> 00:11:25,840 Speaker 1: know dark matter as supposed to interact with matter only 226 00:11:25,880 --> 00:11:29,400 Speaker 1: through gravity. But I suppose if it interacts any through gravity, 227 00:11:29,400 --> 00:11:32,240 Speaker 1: that implies some form of attraction, which means, if we 228 00:11:32,320 --> 00:11:35,120 Speaker 1: regarded as a fluid, it must have some sort of viscosity, which, 229 00:11:35,400 --> 00:11:38,719 Speaker 1: if I remember the definition of a superfluid currictly means 230 00:11:38,760 --> 00:11:41,240 Speaker 1: that can't be a super fluid. Sure, I guess it 231 00:11:41,280 --> 00:11:44,680 Speaker 1: could be anything. We really don't know much about dark 232 00:11:44,720 --> 00:11:49,680 Speaker 1: matter other than it exists and it has gravity. Um, 233 00:11:49,720 --> 00:11:53,120 Speaker 1: so why not? Could be, could be super fluid, could be, 234 00:11:53,840 --> 00:11:58,600 Speaker 1: could be anything? Really m M interesting answers some skepticism. 235 00:11:58,760 --> 00:12:00,480 Speaker 1: Some people were like, I don't know, don't think so 236 00:12:01,800 --> 00:12:04,400 Speaker 1: this one sounds weird to people. I think the idea 237 00:12:04,440 --> 00:12:08,240 Speaker 1: of having like a fluid out in space sounds weird. 238 00:12:08,320 --> 00:12:12,640 Speaker 1: People think of spaces like cold and mostly empty, maybe 239 00:12:12,640 --> 00:12:15,320 Speaker 1: filled with tiny little crystals or particles flying around, But 240 00:12:15,360 --> 00:12:17,120 Speaker 1: like a fluid is a weird thing to think about 241 00:12:17,120 --> 00:12:19,800 Speaker 1: having in space, right, And it seems like a lot 242 00:12:19,800 --> 00:12:21,320 Speaker 1: of people are like, maybe it could be a fluid, 243 00:12:21,360 --> 00:12:23,240 Speaker 1: but a super fluid, I don't know if I would 244 00:12:23,320 --> 00:12:26,360 Speaker 1: give it, you know, supernatural powers. Yeah, well, at least 245 00:12:26,400 --> 00:12:27,920 Speaker 1: one guy is ready to taste it, though, you know 246 00:12:27,960 --> 00:12:31,880 Speaker 1: he's thinking about super soft drinks. Hmm, interesting, super soda, 247 00:12:32,080 --> 00:12:34,960 Speaker 1: super dark soda. Exactly. It's very massive. It's like Coca 248 00:12:35,040 --> 00:12:39,400 Speaker 1: cola dark coke. Give us a call. We got ideas, 249 00:12:39,559 --> 00:12:43,040 Speaker 1: special dark recipe. But a lot of people didn't seem 250 00:12:43,080 --> 00:12:46,040 Speaker 1: to know what even a super fluid is. I guess 251 00:12:46,040 --> 00:12:49,000 Speaker 1: that's not a common word even I'm not sure what 252 00:12:49,040 --> 00:12:51,920 Speaker 1: it quite means. Yeah, super fluids are not the kind 253 00:12:51,960 --> 00:12:54,640 Speaker 1: of thing you have experience with that you don't see 254 00:12:54,679 --> 00:12:56,800 Speaker 1: them in your everyday life. The river that runs through 255 00:12:56,800 --> 00:12:58,640 Speaker 1: the park in the middle of your town doesn't ever 256 00:12:58,720 --> 00:13:01,520 Speaker 1: become a super fluid. You don't make super fluids in 257 00:13:01,559 --> 00:13:05,240 Speaker 1: your kitchen. They're like a weird quantum state of matter 258 00:13:05,360 --> 00:13:09,560 Speaker 1: that we only recently even we're sure could exist. And 259 00:13:09,640 --> 00:13:12,080 Speaker 1: so it's a sort of a new theoretical idea, and 260 00:13:12,080 --> 00:13:15,040 Speaker 1: whenever that happens, people have fun applying into like, oh, 261 00:13:15,120 --> 00:13:17,920 Speaker 1: this is new and cool. Maybe this works also over 262 00:13:17,960 --> 00:13:20,760 Speaker 1: here in this different part of physics where there's something 263 00:13:20,800 --> 00:13:23,080 Speaker 1: we don't understand we have a new hammer. So let's 264 00:13:23,080 --> 00:13:25,120 Speaker 1: see what else could be a nail. Yeah, it seems 265 00:13:25,120 --> 00:13:27,480 Speaker 1: like maybe dark matter being a super fluid could maybe 266 00:13:27,480 --> 00:13:29,839 Speaker 1: explain some of the things we can't quite figure out 267 00:13:29,960 --> 00:13:31,920 Speaker 1: about it. And so Dania, let's step people through this. 268 00:13:32,000 --> 00:13:34,280 Speaker 1: First of all, I guess let's recap what dark matter 269 00:13:34,520 --> 00:13:36,840 Speaker 1: is and what is it that we don't understand about 270 00:13:36,880 --> 00:13:39,360 Speaker 1: it that is making us consider this idea. So we 271 00:13:39,520 --> 00:13:43,120 Speaker 1: think that the universe has a bunch of invisible matter 272 00:13:43,240 --> 00:13:46,040 Speaker 1: in it because we see a lot of gravity out 273 00:13:46,080 --> 00:13:49,640 Speaker 1: there in the universe that we can't explain from visible matter. 274 00:13:49,800 --> 00:13:52,120 Speaker 1: You know, we know that stars are huge balls of 275 00:13:52,200 --> 00:13:54,160 Speaker 1: hydrogen and they have a lot of mass, and so 276 00:13:54,200 --> 00:13:56,480 Speaker 1: they have a lot of gravity, and the Earth spins 277 00:13:56,520 --> 00:13:59,320 Speaker 1: around the Sun, for example, because of the mass of 278 00:13:59,360 --> 00:14:01,760 Speaker 1: all that grab But if you look at a galaxy 279 00:14:01,840 --> 00:14:03,560 Speaker 1: and you add up all of the mass from all 280 00:14:03,600 --> 00:14:06,439 Speaker 1: the stars that you can see, you can't explain all 281 00:14:06,480 --> 00:14:09,920 Speaker 1: the gravity that's happening in the galaxy. Like the galaxy 282 00:14:10,000 --> 00:14:12,760 Speaker 1: is spinning like all galaxies do, and that spinning would 283 00:14:12,800 --> 00:14:15,680 Speaker 1: tend to toss stars into outer space the way like 284 00:14:15,760 --> 00:14:17,760 Speaker 1: ping pong balls on a Merry Go Round. If you spin, 285 00:14:17,840 --> 00:14:20,320 Speaker 1: it would toss those ping pong balls out past the 286 00:14:20,360 --> 00:14:23,160 Speaker 1: Merry Go Round, But the gravity of the galaxy keeps 287 00:14:23,160 --> 00:14:26,000 Speaker 1: those stars in place. That's why this Milky Way is 288 00:14:26,000 --> 00:14:28,360 Speaker 1: not just like throwing all of our stars away. But 289 00:14:28,440 --> 00:14:31,720 Speaker 1: the galaxies are spinning really really fast, and in order 290 00:14:31,720 --> 00:14:34,360 Speaker 1: to hold them in place, they need more gravity than 291 00:14:34,440 --> 00:14:36,840 Speaker 1: we can account for. The gravity from the stars we 292 00:14:36,880 --> 00:14:39,480 Speaker 1: can see doesn't give us enough gravity to hold the 293 00:14:39,480 --> 00:14:42,920 Speaker 1: galaxy together. And on a bigger scale, we also need 294 00:14:43,000 --> 00:14:47,120 Speaker 1: to hold galaxy clusters together. Galaxy clusters are big groups 295 00:14:47,160 --> 00:14:50,400 Speaker 1: of galaxies, and we don't think those galaxies seem to 296 00:14:50,440 --> 00:14:53,920 Speaker 1: have enough mass to hold themselves together. Galaxy clusters are 297 00:14:53,920 --> 00:14:57,040 Speaker 1: also spinning. But if you add a bunch of invisible 298 00:14:57,120 --> 00:15:01,000 Speaker 1: mass to the galaxies, then it all works because it's invisible, 299 00:15:01,120 --> 00:15:04,800 Speaker 1: explains why you can't see it, and it's new matter, 300 00:15:04,960 --> 00:15:08,240 Speaker 1: so it adds more gravity, and so it solves those 301 00:15:08,280 --> 00:15:11,320 Speaker 1: problems if you add this weird new invisible stuff to 302 00:15:11,400 --> 00:15:14,000 Speaker 1: the universe. The weirdest thing about it, though, is that 303 00:15:14,040 --> 00:15:17,040 Speaker 1: you need much more dark matter than visible stuff. It's 304 00:15:17,080 --> 00:15:19,240 Speaker 1: not like you just add a little sprinkling of dark matter. 305 00:15:19,520 --> 00:15:22,240 Speaker 1: You need to take every star and add five stars 306 00:15:22,280 --> 00:15:25,880 Speaker 1: worth of dark matter to explain all the missing gravity. Yeah, 307 00:15:25,880 --> 00:15:28,200 Speaker 1: it's it's almost like dark matter is kind of like 308 00:15:28,240 --> 00:15:31,600 Speaker 1: the missing piece. And what we see of the universe, right, 309 00:15:31,680 --> 00:15:34,160 Speaker 1: and the way the galaxies stick together and the galaxy 310 00:15:34,160 --> 00:15:37,280 Speaker 1: clusters stick together, they stick together more than they should 311 00:15:37,360 --> 00:15:40,640 Speaker 1: given what we can see in them. And so one 312 00:15:40,720 --> 00:15:43,680 Speaker 1: solution is that maybe there's invisible stuff out there that's 313 00:15:43,680 --> 00:15:45,640 Speaker 1: holding it together. Yeah, and this is the kind of 314 00:15:45,640 --> 00:15:48,800 Speaker 1: thing we're always trying to do, is reconcile everything we see. 315 00:15:49,000 --> 00:15:51,600 Speaker 1: We think we understand how gravity works. Let's check it. 316 00:15:51,680 --> 00:15:55,000 Speaker 1: Let's make sure that our explanation makes sense, that it 317 00:15:55,040 --> 00:15:57,160 Speaker 1: works for this scenario. And that's how we discovered oh 318 00:15:57,160 --> 00:15:59,360 Speaker 1: my gosh, it doesn't. And that was the clue that 319 00:15:59,480 --> 00:16:02,280 Speaker 1: maybe it was something else going on, or there was 320 00:16:02,360 --> 00:16:05,880 Speaker 1: something else new out there. But before you believe that, 321 00:16:06,000 --> 00:16:08,800 Speaker 1: just like crazy new idea that the universe is filled 322 00:16:08,800 --> 00:16:11,240 Speaker 1: with a huge amount of invisible stuff you just happened 323 00:16:11,240 --> 00:16:14,200 Speaker 1: and never noticed before, you want other pieces of evidence. 324 00:16:14,200 --> 00:16:17,040 Speaker 1: And so we have other clues that dark matter might 325 00:16:17,040 --> 00:16:19,640 Speaker 1: be real. We see it affecting the way light moves 326 00:16:19,720 --> 00:16:22,760 Speaker 1: through the universe because if it has mass, it changes 327 00:16:22,840 --> 00:16:25,800 Speaker 1: the curvature of space, and so it can lends light. 328 00:16:25,960 --> 00:16:28,480 Speaker 1: We see that it existed in the very early universe 329 00:16:28,480 --> 00:16:32,720 Speaker 1: because it affected the wiggles in the cosmic microwave background radiation, 330 00:16:33,160 --> 00:16:36,440 Speaker 1: these photons from the plasma that filled the universe very 331 00:16:36,520 --> 00:16:38,960 Speaker 1: very early on. And we also know that affected the 332 00:16:38,960 --> 00:16:42,200 Speaker 1: whole way that the universe form, the large scale structure 333 00:16:42,280 --> 00:16:45,320 Speaker 1: of the universe. Galaxies we think wouldn't even exist if 334 00:16:45,400 --> 00:16:49,040 Speaker 1: dark matter hadn't created little gravitational wells to pull stars 335 00:16:49,080 --> 00:16:52,840 Speaker 1: into mostly all hangs together into a very nice story, right, 336 00:16:52,840 --> 00:16:54,560 Speaker 1: But it's kind of interesting. I guess that it's a 337 00:16:54,600 --> 00:16:57,400 Speaker 1: story we made up assuming that what we know of 338 00:16:57,440 --> 00:16:59,960 Speaker 1: the rest of the universe is true. Right, Like, if 339 00:17:00,040 --> 00:17:02,400 Speaker 1: we assume that the laws of fixed work the way 340 00:17:02,400 --> 00:17:04,480 Speaker 1: we think they do, then you sort of need this 341 00:17:04,560 --> 00:17:07,399 Speaker 1: invisible matter to just make what we see make sense. 342 00:17:07,440 --> 00:17:09,560 Speaker 1: But that's only assuming that we're right about the laws 343 00:17:09,560 --> 00:17:13,080 Speaker 1: of physics. Yeah, that's saying gravity works a certain way, 344 00:17:13,200 --> 00:17:15,399 Speaker 1: and so in order to explain this missing gravity, we 345 00:17:15,440 --> 00:17:18,320 Speaker 1: need more mass. But you're right, there are other ideas. 346 00:17:18,400 --> 00:17:21,480 Speaker 1: People have also thought, well, maybe gravity doesn't work the 347 00:17:21,520 --> 00:17:24,120 Speaker 1: way that we thought maybe there isn't any missing gravity. 348 00:17:24,240 --> 00:17:27,560 Speaker 1: It's just signs that our theory of gravity is wrong. 349 00:17:28,160 --> 00:17:31,160 Speaker 1: And people have tried to modify the theory of gravity 350 00:17:31,200 --> 00:17:33,760 Speaker 1: to explain what we see, and this is called Mond 351 00:17:34,320 --> 00:17:38,160 Speaker 1: modified Newtonian dynamics. The theory says that instead of gravity 352 00:17:38,200 --> 00:17:41,920 Speaker 1: going like one over distance square the way Newton said, 353 00:17:42,160 --> 00:17:45,959 Speaker 1: there's another factor there that when things have very low accelerations, 354 00:17:45,960 --> 00:17:48,560 Speaker 1: gravity is a little bit different. It gets a little stronger. 355 00:17:48,640 --> 00:17:51,080 Speaker 1: So if you tweak gravity in just this way, you 356 00:17:51,080 --> 00:17:54,760 Speaker 1: can also explain how galaxies rotate without using dark matter. 357 00:17:55,359 --> 00:17:57,920 Speaker 1: That's really interesting. So it could be that dark matter 358 00:17:58,320 --> 00:18:00,960 Speaker 1: is not dark matter at all, Like maybe we just 359 00:18:01,119 --> 00:18:03,480 Speaker 1: have the laws of physics a little bit wrong. But 360 00:18:03,520 --> 00:18:06,600 Speaker 1: does that explain everything about the way the galaxies stick 361 00:18:06,600 --> 00:18:09,560 Speaker 1: together and even the gravitational lensing. No, So Mond, this 362 00:18:09,680 --> 00:18:13,200 Speaker 1: alternative theory gravity does in fact a better job at 363 00:18:13,240 --> 00:18:16,879 Speaker 1: explaining how galaxies rotate than dark matter does. There's some 364 00:18:16,920 --> 00:18:19,840 Speaker 1: things about galaxy rotations that dark matter just can't seem 365 00:18:19,880 --> 00:18:22,600 Speaker 1: to get right, but it doesn't explain everything else that 366 00:18:22,720 --> 00:18:25,240 Speaker 1: dark matter does. Like Mond does not do a good 367 00:18:25,320 --> 00:18:29,359 Speaker 1: job of describing how galaxy clusters rotate and spin. Around themselves, 368 00:18:29,440 --> 00:18:31,760 Speaker 1: and it's much more difficult for it to explain, like 369 00:18:31,800 --> 00:18:35,520 Speaker 1: the cosmic microwave background and lensing and all sorts of 370 00:18:35,600 --> 00:18:38,600 Speaker 1: other very strong evidence for dark matter. So mond is 371 00:18:38,600 --> 00:18:40,560 Speaker 1: sort of a nice idea you can explain one thing 372 00:18:40,640 --> 00:18:43,480 Speaker 1: actually better than dark matter can. But dark matter is 373 00:18:43,520 --> 00:18:46,399 Speaker 1: sort of like a stronger idea across the board. But 374 00:18:46,480 --> 00:18:48,760 Speaker 1: neither of them, I guess, is perfect. And let's maybe 375 00:18:48,760 --> 00:18:50,520 Speaker 1: dig into that a little bit, like what is it 376 00:18:50,560 --> 00:18:53,280 Speaker 1: about the idea that dark matter is invisible stuff that 377 00:18:53,480 --> 00:18:55,600 Speaker 1: doesn't explain what we see out there? So by now 378 00:18:55,640 --> 00:18:58,200 Speaker 1: we've seen a lot of galaxies, and what we try 379 00:18:58,240 --> 00:19:00,600 Speaker 1: to do is understand like how am my dark matter 380 00:19:00,720 --> 00:19:03,160 Speaker 1: is in a galaxy versus how much normal matter? And 381 00:19:03,400 --> 00:19:05,960 Speaker 1: is that common across galaxies? Like do all galaxies have 382 00:19:06,000 --> 00:19:08,440 Speaker 1: the same amount of dark matter and the same amount 383 00:19:08,440 --> 00:19:11,040 Speaker 1: of normal matter? And we also try to understand how 384 00:19:11,080 --> 00:19:13,520 Speaker 1: that could have happened. You know, if dark matter is 385 00:19:13,560 --> 00:19:16,600 Speaker 1: this weird particle, this new heavy, invisible thing, then it 386 00:19:16,600 --> 00:19:18,879 Speaker 1: would have clustered together and we can make models for 387 00:19:19,080 --> 00:19:21,600 Speaker 1: how that would have happened informed galaxies. We look out 388 00:19:21,600 --> 00:19:24,200 Speaker 1: into the universe, the galaxies we see don't really line 389 00:19:24,280 --> 00:19:26,840 Speaker 1: up with what we expect for dark matter. So one 390 00:19:26,880 --> 00:19:29,760 Speaker 1: thing specifically we look at is a relationship between how 391 00:19:29,800 --> 00:19:33,000 Speaker 1: bright the galaxies are and how fast they are spinning. 392 00:19:33,440 --> 00:19:35,600 Speaker 1: How bright they are is really interesting because it tells 393 00:19:35,640 --> 00:19:37,920 Speaker 1: us like how much normal matter is there, how many stars, 394 00:19:38,400 --> 00:19:41,160 Speaker 1: how fast they're spinning should tell us something about how 395 00:19:41,240 --> 00:19:43,600 Speaker 1: much dark matter there is in the galaxy. And if 396 00:19:43,640 --> 00:19:45,840 Speaker 1: you do a bunch of simulations, then you expect like 397 00:19:46,200 --> 00:19:49,439 Speaker 1: a loose relationship there. You expect, like some galaxies to 398 00:19:49,480 --> 00:19:50,879 Speaker 1: have a lot of dark matter and something to have 399 00:19:50,920 --> 00:19:53,080 Speaker 1: a little bit, but there to be a lot of variation. 400 00:19:53,480 --> 00:19:55,560 Speaker 1: What we see when we look at these galaxies, though, 401 00:19:55,600 --> 00:19:58,280 Speaker 1: is that there's a very very tight relationship. It's like 402 00:19:58,359 --> 00:20:01,600 Speaker 1: almost no variation, like the amount of stars in a 403 00:20:01,640 --> 00:20:03,639 Speaker 1: galaxy and amount of dark matter and the galaxy has 404 00:20:03,680 --> 00:20:06,920 Speaker 1: a very very close relationship, which we think is weird 405 00:20:06,960 --> 00:20:09,359 Speaker 1: and we can't explain with our models. You mean, like 406 00:20:09,400 --> 00:20:11,880 Speaker 1: when you look at the galaxies out there in the universe, 407 00:20:11,920 --> 00:20:14,800 Speaker 1: they almost have the same proportion of regular matter and 408 00:20:14,920 --> 00:20:16,600 Speaker 1: dark matter. I think that's what you're saying, right, Like, 409 00:20:16,640 --> 00:20:18,879 Speaker 1: there aren't galaxies out there with a lot of dark matter, 410 00:20:18,960 --> 00:20:20,720 Speaker 1: and there aren't a lot of galaxies with a little 411 00:20:20,720 --> 00:20:23,160 Speaker 1: bit of dark matter, which is weird. But I guess 412 00:20:23,240 --> 00:20:25,120 Speaker 1: to me, it's weird that you would think it's weird. 413 00:20:25,240 --> 00:20:26,960 Speaker 1: Why wouldn't they all it's sort of the same. But 414 00:20:27,000 --> 00:20:28,800 Speaker 1: they were all made in the Big Bang, you know, 415 00:20:28,960 --> 00:20:32,000 Speaker 1: because there's a random element here, right, Like, how do 416 00:20:32,119 --> 00:20:36,119 Speaker 1: galaxies form? Anyway? It comes from a quantum fluctuation in 417 00:20:36,160 --> 00:20:38,879 Speaker 1: the initial seeds of the universe that gave you a 418 00:20:38,960 --> 00:20:42,720 Speaker 1: slight over density in the dark matter that pulled together 419 00:20:42,760 --> 00:20:45,720 Speaker 1: a little well and then grab some stuff. And you know, 420 00:20:45,760 --> 00:20:48,639 Speaker 1: we do expect some relationship. We expect there to be 421 00:20:48,680 --> 00:20:50,679 Speaker 1: a relationship between the amount of matter and the amount 422 00:20:50,680 --> 00:20:52,840 Speaker 1: of dark matter, because in the beginning we think this 423 00:20:52,880 --> 00:20:56,040 Speaker 1: stuff is mostly evenly spread out. But we also expect 424 00:20:56,080 --> 00:20:58,720 Speaker 1: some variation. And when they do simulations to try to 425 00:20:58,720 --> 00:21:01,240 Speaker 1: predict what kind of variation we see and we run 426 00:21:01,280 --> 00:21:03,119 Speaker 1: all of our laws of physics, we see a much 427 00:21:03,200 --> 00:21:05,960 Speaker 1: wider variation in our simulations than we see out there 428 00:21:06,000 --> 00:21:09,520 Speaker 1: in the actual universe. That tells us like, maybe there's 429 00:21:09,560 --> 00:21:11,840 Speaker 1: something wrong with this theory. That's something that we're putting 430 00:21:11,880 --> 00:21:14,080 Speaker 1: into our simulations that isn't doing a good job of 431 00:21:14,240 --> 00:21:17,399 Speaker 1: describing what we're actually seeing. I think you're saying that 432 00:21:17,440 --> 00:21:21,040 Speaker 1: the ratio between dark matter and regular matter is too constant, 433 00:21:21,119 --> 00:21:25,040 Speaker 1: like it's too consistent across the board of the universe, 434 00:21:25,160 --> 00:21:27,399 Speaker 1: which means that maybe the problem is that what we 435 00:21:27,480 --> 00:21:30,040 Speaker 1: expect to see in the universe is wrong or something. Yeah, 436 00:21:30,560 --> 00:21:32,640 Speaker 1: because for that to happen, you might expect some sort 437 00:21:32,680 --> 00:21:35,080 Speaker 1: of interaction between them, for them to like turn back 438 00:21:35,119 --> 00:21:37,280 Speaker 1: and forth into each other, or interact with each other, 439 00:21:37,520 --> 00:21:40,119 Speaker 1: some process that's keeping them so tightly coupled. But we 440 00:21:40,160 --> 00:21:43,240 Speaker 1: think that dark matter and atomic matter don't interact except 441 00:21:43,240 --> 00:21:46,359 Speaker 1: through gravity, so we don't have a process for making 442 00:21:46,400 --> 00:21:50,960 Speaker 1: this happen. The alternative theory MOND actually predicts this perfectly, 443 00:21:51,480 --> 00:21:54,080 Speaker 1: like Mon says, there is no dark matter, there's just 444 00:21:54,240 --> 00:21:57,760 Speaker 1: normal matter, and gravity changes how things spin, and the 445 00:21:57,840 --> 00:22:01,520 Speaker 1: apparent rotation of velocity of these galaxies should be very 446 00:22:01,600 --> 00:22:05,320 Speaker 1: tightly connected to their brightness because the rotation velocity just 447 00:22:05,480 --> 00:22:08,959 Speaker 1: comes from stars. So the Mond prediction is like bang 448 00:22:09,000 --> 00:22:12,240 Speaker 1: on exactly what we see, whereas the dark matter prediction 449 00:22:12,320 --> 00:22:14,159 Speaker 1: is sort of like scattered all over the place and 450 00:22:14,240 --> 00:22:16,639 Speaker 1: doesn't do a good job of describing what we see. 451 00:22:17,040 --> 00:22:19,320 Speaker 1: For astronomy nerds out there. This is called the Tully 452 00:22:19,400 --> 00:22:22,439 Speaker 1: Fisher relation. M I think you're saying that maybe this 453 00:22:22,520 --> 00:22:25,000 Speaker 1: idea of Mond, that maybe our laws of physics are wrong, 454 00:22:25,600 --> 00:22:29,440 Speaker 1: does a better job of explaining the consistency of what 455 00:22:29,480 --> 00:22:32,080 Speaker 1: we see out there in the galaxies. Like, it makes 456 00:22:32,119 --> 00:22:34,760 Speaker 1: more sense that gravity works differently than we think it does, 457 00:22:35,000 --> 00:22:37,200 Speaker 1: and then it would be for other to be a 458 00:22:37,240 --> 00:22:39,440 Speaker 1: bunch of invisible mass. Yeah, it does a better job 459 00:22:39,480 --> 00:22:43,679 Speaker 1: of explaining the relationship between galaxy brightness and rotation that 460 00:22:43,760 --> 00:22:46,080 Speaker 1: we see in the universe. We see them much more 461 00:22:46,160 --> 00:22:49,080 Speaker 1: tightly coupled and connected in the universe than we would 462 00:22:49,080 --> 00:22:50,919 Speaker 1: expect if it was due to dark matter. If you've 463 00:22:50,960 --> 00:22:52,880 Speaker 1: got like a random sampling of how much dark matter 464 00:22:52,880 --> 00:22:54,760 Speaker 1: and how much normal matter, you expect there to be 465 00:22:54,760 --> 00:22:57,680 Speaker 1: more of a spread. But Mond predicts a very tight 466 00:22:57,720 --> 00:23:00,400 Speaker 1: relationship because there is no dark matter, So it does 467 00:23:00,400 --> 00:23:03,040 Speaker 1: a better job of predicting what we actually see out 468 00:23:03,040 --> 00:23:04,679 Speaker 1: there in the universe. This is like kind of a 469 00:23:04,680 --> 00:23:08,199 Speaker 1: headache for dark matter as a theory. Interesting, like it 470 00:23:08,280 --> 00:23:11,320 Speaker 1: has its failings. The idea that it's invisible matter, and 471 00:23:11,400 --> 00:23:13,600 Speaker 1: this idea that maybe the laws of physics are wrong 472 00:23:13,720 --> 00:23:15,639 Speaker 1: comes in and says, hey, I can fix that, but 473 00:23:15,800 --> 00:23:18,480 Speaker 1: maybe it doesn't fix everything, which is why it's still 474 00:23:18,520 --> 00:23:21,760 Speaker 1: not the prevailing theory. Yeah, exactly, But it's been like 475 00:23:21,800 --> 00:23:23,879 Speaker 1: a real thorn in the side of dark matter for 476 00:23:23,920 --> 00:23:25,680 Speaker 1: a long time and keeps a lot of people, I think, 477 00:23:25,680 --> 00:23:28,640 Speaker 1: from accepting this idea that dark matter might be real. Well, 478 00:23:28,680 --> 00:23:30,960 Speaker 1: there is a new theory, a new idea that maybe 479 00:23:31,080 --> 00:23:33,520 Speaker 1: would make dark matter make more sense, and that's the 480 00:23:33,520 --> 00:23:36,400 Speaker 1: idea that it maybe it's a super fluid. So let's 481 00:23:36,400 --> 00:23:39,120 Speaker 1: get into what a super fluid is and whether dark 482 00:23:39,160 --> 00:23:42,760 Speaker 1: matter could be one of these superpowered fluids. But first 483 00:23:42,800 --> 00:23:57,439 Speaker 1: let's take a quick break. All right, we're asking the question, 484 00:23:57,760 --> 00:24:00,600 Speaker 1: could dark matter be a super fluid? It? And we're 485 00:24:00,600 --> 00:24:02,720 Speaker 1: asking the question because there are some things about dark 486 00:24:02,760 --> 00:24:05,439 Speaker 1: matter that we can't quite explain out there. Even if 487 00:24:05,440 --> 00:24:07,760 Speaker 1: we assume it's some kind of stuff, some kind of particles, 488 00:24:07,800 --> 00:24:11,040 Speaker 1: some kind of fluid, it doesn't quite explain the ratio 489 00:24:11,160 --> 00:24:13,479 Speaker 1: of regular matter and dark matter we see out there 490 00:24:13,480 --> 00:24:15,760 Speaker 1: in the universe. Yeah, that's right, And so people are 491 00:24:15,760 --> 00:24:17,800 Speaker 1: trying to be creative. They're saying, like, dark matter by 492 00:24:17,800 --> 00:24:21,320 Speaker 1: itself doesn't quite work as a theory. Mond by itself 493 00:24:21,400 --> 00:24:23,919 Speaker 1: has lots more problems than dark matter by itself, like, 494 00:24:23,960 --> 00:24:25,919 Speaker 1: neither of them are perfect. Is there some way we 495 00:24:25,920 --> 00:24:28,639 Speaker 1: could take dark matter and make it a little Mond 496 00:24:28,720 --> 00:24:31,200 Speaker 1: dear right, to try to capture some of the things 497 00:24:31,200 --> 00:24:34,159 Speaker 1: that Mond has. Remember, the key feature of minds that 498 00:24:34,240 --> 00:24:38,159 Speaker 1: it changes the effect of gravity over some distances. So 499 00:24:38,200 --> 00:24:40,480 Speaker 1: people were like, well, is there any way we could 500 00:24:40,760 --> 00:24:43,800 Speaker 1: change dark matter or tweak dark matter so that it 501 00:24:44,200 --> 00:24:46,879 Speaker 1: basically has the same effect as Mond, but only in 502 00:24:46,920 --> 00:24:49,879 Speaker 1: these scenarios the hearts of galaxies where dark matter seems 503 00:24:49,920 --> 00:24:52,280 Speaker 1: to be having a problem all right, And so the 504 00:24:52,320 --> 00:24:54,800 Speaker 1: idea is that maybe dark matter is a super fluid, 505 00:24:54,880 --> 00:24:57,800 Speaker 1: which is like a superpowered fluid that was I don't know, 506 00:24:57,920 --> 00:25:01,280 Speaker 1: born in krypton or something inherited power ring from an am. 507 00:25:01,359 --> 00:25:04,120 Speaker 1: The superfluid is not from cartoons and not just from 508 00:25:04,119 --> 00:25:07,040 Speaker 1: science fiction. It's a real thing. A couple of Nobel 509 00:25:07,119 --> 00:25:10,400 Speaker 1: Prizes have been won already because of superfluids, and they're 510 00:25:10,440 --> 00:25:15,160 Speaker 1: called superfluids sort of analogy to superconductors, right. A superconductor 511 00:25:15,240 --> 00:25:18,359 Speaker 1: is something that conducts electricity, so you can send energy 512 00:25:18,480 --> 00:25:21,080 Speaker 1: down a wire if it's superconducting and lose none of 513 00:25:21,119 --> 00:25:23,200 Speaker 1: it right, you don't turn any of it into heat, 514 00:25:23,280 --> 00:25:27,320 Speaker 1: and so super fluid is similar. It's a liquid that flows, 515 00:25:27,320 --> 00:25:30,360 Speaker 1: but without any internal resistance, so the bits just sort 516 00:25:30,359 --> 00:25:33,000 Speaker 1: of slide by each other. It doesn't heat up at 517 00:25:33,040 --> 00:25:35,720 Speaker 1: all as it flows, doesn't lose energy. Like if you 518 00:25:35,760 --> 00:25:37,720 Speaker 1: take a bucket of water and you put your finger 519 00:25:37,760 --> 00:25:39,840 Speaker 1: in it and spin it, you get a little vortex 520 00:25:39,880 --> 00:25:42,840 Speaker 1: that's forming. But eventually that vortex will sort of peter 521 00:25:42,960 --> 00:25:45,280 Speaker 1: out right, the energy will diffuse and the water will 522 00:25:45,280 --> 00:25:48,840 Speaker 1: stop moving. In a superfluid, that doesn't happen. You start 523 00:25:48,880 --> 00:25:52,440 Speaker 1: a vortex and it just spins forever. Wow, it's super interesting. 524 00:25:52,520 --> 00:25:55,840 Speaker 1: I guess that's the idea of zero viscosity, which means 525 00:25:55,840 --> 00:25:58,680 Speaker 1: no friction between the molecules of the fluid. But I 526 00:25:58,680 --> 00:26:01,000 Speaker 1: guess maybe let's dig in a little. This might be interesting. 527 00:26:01,119 --> 00:26:04,320 Speaker 1: What exactly is viscosity or what exactly is friction? Like? 528 00:26:04,359 --> 00:26:06,199 Speaker 1: Where does that come from? So it comes from the 529 00:26:06,240 --> 00:26:09,359 Speaker 1: interaction of the bits inside of it. Right, when we 530 00:26:09,400 --> 00:26:12,680 Speaker 1: talk about like an ideal gas, we're talking about particles 531 00:26:12,720 --> 00:26:15,560 Speaker 1: flying through space, but we ignore the possibility that they 532 00:26:15,560 --> 00:26:18,639 Speaker 1: can bump off each other and exchange energy. In real life, 533 00:26:18,640 --> 00:26:21,040 Speaker 1: the particles inside of gas can bump off each other, 534 00:26:21,119 --> 00:26:23,919 Speaker 1: can exchange energy, and the same thing with a liquid. 535 00:26:23,960 --> 00:26:27,440 Speaker 1: In the case of a zero viscosity liquid a super fluid, 536 00:26:27,560 --> 00:26:29,800 Speaker 1: then the particles don't really bump off each other and 537 00:26:29,800 --> 00:26:33,240 Speaker 1: they can like change places without losing any of their energy. 538 00:26:33,440 --> 00:26:34,959 Speaker 1: What do you mean they don't bump into each other. 539 00:26:35,080 --> 00:26:37,600 Speaker 1: They do bump, but they don't lose energy, or they 540 00:26:37,680 --> 00:26:40,040 Speaker 1: don't bump at all, Like the things inside of the 541 00:26:40,040 --> 00:26:42,440 Speaker 1: liquid don't interact with it with the self. When you're 542 00:26:42,440 --> 00:26:45,160 Speaker 1: thinking about a liquid, it's sort of like an emergent object, 543 00:26:45,320 --> 00:26:47,680 Speaker 1: and it's easiest to think about it like layers of liquid. 544 00:26:47,760 --> 00:26:51,480 Speaker 1: Imagine like two layers of a liquid passing by each other, 545 00:26:51,680 --> 00:26:54,520 Speaker 1: and think about whether there's like friction between those layers. Say, 546 00:26:54,520 --> 00:26:56,840 Speaker 1: for example, say for example, you have a tube and 547 00:26:56,840 --> 00:26:59,359 Speaker 1: you're pushing some liquid through it, right, then if it's 548 00:26:59,359 --> 00:27:01,640 Speaker 1: a very vis gets liquid, it's going to flow more 549 00:27:01,720 --> 00:27:05,280 Speaker 1: rapidly near the center than near the walls, because I 550 00:27:05,280 --> 00:27:08,680 Speaker 1: get the fluid particles near the walls of the tube 551 00:27:08,680 --> 00:27:11,600 Speaker 1: are hitting the particles of the tube, right, and so 552 00:27:11,640 --> 00:27:14,359 Speaker 1: they lose energy. They're like bumping against the wall, and 553 00:27:14,400 --> 00:27:16,080 Speaker 1: it's not just that they're bumping against the wall. Think 554 00:27:16,080 --> 00:27:18,160 Speaker 1: about like, as the layers are passing by each other, 555 00:27:18,280 --> 00:27:21,119 Speaker 1: are the particles grabbing at each other? Like what is 556 00:27:21,160 --> 00:27:24,120 Speaker 1: friction anyway? Like if you run your finger along the surface, 557 00:27:24,160 --> 00:27:26,960 Speaker 1: why is kinetic energy getting turned into heat? Because the 558 00:27:27,000 --> 00:27:30,040 Speaker 1: particles in your finger are grabbing at the particles on 559 00:27:30,080 --> 00:27:33,760 Speaker 1: the table. There's little deformities and there's bonds between them 560 00:27:33,760 --> 00:27:36,560 Speaker 1: that are getting broken and reformed. And the same thing 561 00:27:36,600 --> 00:27:39,480 Speaker 1: happens inside liquid. When you have like layers of liquid 562 00:27:39,520 --> 00:27:42,000 Speaker 1: passing by each other, they have an interaction, then they 563 00:27:42,040 --> 00:27:44,480 Speaker 1: can grab at each other and sort of like slow 564 00:27:44,560 --> 00:27:47,879 Speaker 1: the next layer down and it's super fluid, that doesn't happen, 565 00:27:48,080 --> 00:27:49,800 Speaker 1: and the layers can sort of like pass by each 566 00:27:49,800 --> 00:27:53,000 Speaker 1: other without any friction at all. And why is it? 567 00:27:53,040 --> 00:27:56,080 Speaker 1: I guess it just depends on the interaction between the particles. Right. 568 00:27:56,119 --> 00:27:57,639 Speaker 1: It's not something you can do with the normal liquid 569 00:27:57,720 --> 00:27:59,960 Speaker 1: very easily. It's a quantum property, right, It's not something 570 00:28:00,119 --> 00:28:02,880 Speaker 1: you can really understand at an intuitive level just thinking 571 00:28:02,920 --> 00:28:05,199 Speaker 1: about little balls. Instead, you need to think about these 572 00:28:05,240 --> 00:28:07,960 Speaker 1: objects as quantum objects, which means you think about their 573 00:28:08,000 --> 00:28:11,120 Speaker 1: wave functions and when these things get really really cold, 574 00:28:11,400 --> 00:28:14,439 Speaker 1: then you have very little uncertainty on their temperature that 575 00:28:14,480 --> 00:28:18,320 Speaker 1: their wave functions grow really really wide, because the Heisenberg 576 00:28:18,359 --> 00:28:21,040 Speaker 1: and certainty principle tells you can't know something's momentum and 577 00:28:21,080 --> 00:28:24,200 Speaker 1: its location very very well. So when you cool something down, 578 00:28:24,200 --> 00:28:27,400 Speaker 1: its wave function grows very very large. So now instead 579 00:28:27,400 --> 00:28:29,560 Speaker 1: of having just like a bunch of little particles bouncing 580 00:28:29,560 --> 00:28:31,359 Speaker 1: around that you can sort of think of a particles, 581 00:28:31,440 --> 00:28:34,840 Speaker 1: you have these overlapping wave functions between these objects, and 582 00:28:34,880 --> 00:28:37,520 Speaker 1: they form like one big quantum state, and they tend 583 00:28:37,560 --> 00:28:40,840 Speaker 1: to move like all together instead of interacting with each other, 584 00:28:41,080 --> 00:28:44,160 Speaker 1: so they're like more tightly coupled to each other weirdly, 585 00:28:44,320 --> 00:28:47,400 Speaker 1: which gives this super fluid state. I see, I guess 586 00:28:47,400 --> 00:28:49,520 Speaker 1: that you're saying. I think the cold or something gets 587 00:28:49,600 --> 00:28:52,120 Speaker 1: the bigger the wave function of the particles gets, which 588 00:28:52,160 --> 00:28:54,880 Speaker 1: means that their things get fuzzier almost in a way, 589 00:28:55,000 --> 00:28:57,440 Speaker 1: right like instead of a little tiny ball, suddenly it's 590 00:28:57,480 --> 00:29:00,720 Speaker 1: more like a hazy blob. And it's kind of hard 591 00:29:00,720 --> 00:29:03,280 Speaker 1: maybe for too hazy blobs to really drag on each other. 592 00:29:03,440 --> 00:29:04,880 Speaker 1: Is that kind of what you're saying. Yeah, And it 593 00:29:04,920 --> 00:29:07,760 Speaker 1: acts more coherently instead of individual particles which you can 594 00:29:07,800 --> 00:29:10,280 Speaker 1: grab at each other. Now it's like a huge train 595 00:29:10,320 --> 00:29:13,400 Speaker 1: of particles that tend to move together rather than bumping 596 00:29:13,440 --> 00:29:16,880 Speaker 1: against each other. So it's like it's all much more coordinated. Now. 597 00:29:17,000 --> 00:29:18,920 Speaker 1: It's not like a random crowd of people bumping into 598 00:29:18,960 --> 00:29:21,840 Speaker 1: each other. Now it's like a tightly packed formation of 599 00:29:21,840 --> 00:29:24,080 Speaker 1: a marching band walking down the street. But they don't 600 00:29:24,080 --> 00:29:25,480 Speaker 1: bump into each other at all. They just sort of 601 00:29:25,520 --> 00:29:28,200 Speaker 1: like flu and so this happens. For example, here on Earth, 602 00:29:28,240 --> 00:29:30,760 Speaker 1: of you cool helium a lot, you get a Bose 603 00:29:30,800 --> 00:29:34,160 Speaker 1: Einstein concert which is super fluid. The first demonstration of 604 00:29:34,200 --> 00:29:38,200 Speaker 1: this was in super fluid helium. We get the Nobel 605 00:29:38,280 --> 00:29:40,960 Speaker 1: Prize and Physics at Stanford for that. That wasn't actually 606 00:29:41,000 --> 00:29:44,080 Speaker 1: a Bose Einstein condensate, but it is. A super fluid 607 00:29:44,200 --> 00:29:47,480 Speaker 1: can flow without losing any energy. Another example of a 608 00:29:47,520 --> 00:29:50,840 Speaker 1: super fluid is a Bose Einstein condensate. Another special state 609 00:29:50,880 --> 00:29:53,480 Speaker 1: of matter rape a whole podcast about that again, where 610 00:29:53,480 --> 00:29:56,440 Speaker 1: you're cooling atoms down in a trap to make them 611 00:29:56,520 --> 00:29:58,880 Speaker 1: very very cold and overlapping. So they have other weird 612 00:29:58,960 --> 00:30:02,520 Speaker 1: quantum properties as well, which include being a super fluid. 613 00:30:02,640 --> 00:30:05,120 Speaker 1: We also think we have seen super fluid sort of 614 00:30:05,160 --> 00:30:09,720 Speaker 1: indirectly inside the large Hadron collider. When we smash big 615 00:30:09,760 --> 00:30:13,240 Speaker 1: atoms together, like lead nuclei and gold nuclei, we can 616 00:30:13,280 --> 00:30:16,400 Speaker 1: make this state of matter called a cork gluon plasma. 617 00:30:16,480 --> 00:30:18,240 Speaker 1: And one of the features of it, we think, is 618 00:30:18,240 --> 00:30:20,560 Speaker 1: that there's a little bit of super fluidity, very very 619 00:30:20,600 --> 00:30:23,360 Speaker 1: briefly at the heart of that thing while it exists. 620 00:30:23,520 --> 00:30:25,520 Speaker 1: I mean, when you smash particles together, you get so 621 00:30:25,600 --> 00:30:29,720 Speaker 1: much density of energy, and these particles really packed together 622 00:30:29,760 --> 00:30:32,080 Speaker 1: that they behave like a super fluid for a tiny 623 00:30:32,120 --> 00:30:34,040 Speaker 1: little bit. Yeah, for a tiny little bit, even though 624 00:30:34,040 --> 00:30:37,080 Speaker 1: it's super duper hot. It's also so dense that these 625 00:30:37,080 --> 00:30:40,960 Speaker 1: particles undergo this new phase change into a cork gluon plasma, 626 00:30:41,040 --> 00:30:43,160 Speaker 1: which can also be a super fluid. So a super 627 00:30:43,160 --> 00:30:45,400 Speaker 1: fluid isn't like one unique state of matter. It's like 628 00:30:45,400 --> 00:30:47,560 Speaker 1: a description of a phase of matter, the way like 629 00:30:47,640 --> 00:30:51,240 Speaker 1: some phases of matter conduct electricity and some don't. Some 630 00:30:51,280 --> 00:30:53,880 Speaker 1: phases of matter are fluid and some are super fluid 631 00:30:54,240 --> 00:30:56,880 Speaker 1: and others aren't. So these are just examples of places 632 00:30:56,920 --> 00:31:00,320 Speaker 1: where we have seen super fluidity happening, Like really is 633 00:31:00,360 --> 00:31:02,600 Speaker 1: a thing in the universe. We're sure about that. That's 634 00:31:02,640 --> 00:31:05,400 Speaker 1: not a hypothetical thing, and we think it might even 635 00:31:05,440 --> 00:31:08,320 Speaker 1: be what's happening inside of neutron stars, right, Yeah, the 636 00:31:08,320 --> 00:31:10,480 Speaker 1: inside of neutron stars is a lot like a cork 637 00:31:10,520 --> 00:31:13,640 Speaker 1: glow on plasma. It's very very dense, and the particles 638 00:31:13,640 --> 00:31:16,440 Speaker 1: get squeezed together and their wave functions start to overlap. 639 00:31:16,480 --> 00:31:19,160 Speaker 1: And we don't really know what happens inside a neutron 640 00:31:19,200 --> 00:31:21,840 Speaker 1: star because it's some state of matter that we can't 641 00:31:21,880 --> 00:31:25,280 Speaker 1: really access anywhere else, and all the forces come into play, 642 00:31:25,320 --> 00:31:28,880 Speaker 1: including gravity and the strong force, and it really tests 643 00:31:28,920 --> 00:31:31,840 Speaker 1: our ability to even do calculations or predicular what might happen. 644 00:31:31,960 --> 00:31:34,680 Speaker 1: We think that weird states of matter like nuclear pasta 645 00:31:35,160 --> 00:31:38,360 Speaker 1: might occur, and there might also be super fluid states 646 00:31:38,400 --> 00:31:40,760 Speaker 1: inside the heart of a neutron star. But is there 647 00:31:40,800 --> 00:31:44,240 Speaker 1: generally like a recipe for making super fluids? Like, what's 648 00:31:44,280 --> 00:31:46,800 Speaker 1: the thing that makes all of these different examples? What 649 00:31:46,920 --> 00:31:48,800 Speaker 1: do they have in common? They all have in common 650 00:31:48,920 --> 00:31:52,720 Speaker 1: high density. So you squeeze these particles together basically so 651 00:31:52,800 --> 00:31:55,479 Speaker 1: that their wave functions are overlapping, and that's how you 652 00:31:55,520 --> 00:31:58,239 Speaker 1: achieve it. It's easier to do that if they're very 653 00:31:58,320 --> 00:32:01,120 Speaker 1: very low temperature because they're way from are larger. But 654 00:32:01,160 --> 00:32:03,600 Speaker 1: if you get high enough density, you can also achieve 655 00:32:03,640 --> 00:32:05,880 Speaker 1: it even at high temperatures, like the inside of a 656 00:32:05,880 --> 00:32:09,600 Speaker 1: neutron star. But the crucial thing is density. Wonever. It's like, 657 00:32:09,680 --> 00:32:12,480 Speaker 1: you know, taking a bunch of water balloons. When you 658 00:32:12,520 --> 00:32:16,280 Speaker 1: squeeze them together, they almost become super fluid. Haven't you 659 00:32:16,320 --> 00:32:19,280 Speaker 1: been to a birthday party recently? He saw this happen. Well, like, 660 00:32:19,320 --> 00:32:21,800 Speaker 1: if you have a bunch of water balloons out and 661 00:32:21,840 --> 00:32:24,360 Speaker 1: they're really far spread, far apart, they sort of behaved 662 00:32:24,440 --> 00:32:26,960 Speaker 1: like maybe like little particles, but if you sort of 663 00:32:26,960 --> 00:32:29,160 Speaker 1: packed them together in a bucket, they kind of act 664 00:32:29,200 --> 00:32:31,960 Speaker 1: like a fluid. Right, Yeah, that's true. I never thought 665 00:32:31,960 --> 00:32:34,640 Speaker 1: about what it's like for a bunch of water balloons 666 00:32:34,680 --> 00:32:36,720 Speaker 1: to slide out of a bucket. Have you like dumped 667 00:32:36,760 --> 00:32:39,800 Speaker 1: a bucket of water balloons on somebody's head before? Yeah? Yeah, 668 00:32:39,880 --> 00:32:43,440 Speaker 1: super super flat water balloons. Actually that sounds like super fun. 669 00:32:43,600 --> 00:32:46,320 Speaker 1: But you're exactly right. When simple things come together, they 670 00:32:46,320 --> 00:32:49,560 Speaker 1: can do new, weird things. And that's the whole amazing 671 00:32:49,720 --> 00:32:52,640 Speaker 1: size of chemistry. Right. We have these phases of matter 672 00:32:52,960 --> 00:32:55,120 Speaker 1: that come out of the way, these particles interact with 673 00:32:55,120 --> 00:32:57,600 Speaker 1: each other or don't interact with each other, and generate 674 00:32:57,680 --> 00:33:02,040 Speaker 1: these emergent properties electrical activity or shiny nous or liquid 675 00:33:02,080 --> 00:33:04,880 Speaker 1: phases or other weird phases of matter. It's incredible what 676 00:33:05,040 --> 00:33:07,720 Speaker 1: matter in the universe can do. The variety of things 677 00:33:07,760 --> 00:33:09,800 Speaker 1: that come out just of the basic laws from the 678 00:33:09,840 --> 00:33:13,560 Speaker 1: interactions at the microphysical level. It always amazes me. M Okay, 679 00:33:13,600 --> 00:33:15,800 Speaker 1: So that's what a super fluid is. And now the 680 00:33:15,880 --> 00:33:19,280 Speaker 1: idea is that maybe dark matter could be a super fluid. 681 00:33:19,360 --> 00:33:21,479 Speaker 1: So it's the idea that dark matter is made out 682 00:33:21,520 --> 00:33:23,920 Speaker 1: of little particles and then when you somehow get them 683 00:33:23,920 --> 00:33:26,520 Speaker 1: really close to each other, they behave like a super fluid. Yeah. 684 00:33:26,640 --> 00:33:29,280 Speaker 1: The idea is that dark matter is still dark matter. 685 00:33:29,320 --> 00:33:33,800 Speaker 1: It's still some particle that's invisible and intangible and doesn't 686 00:33:33,840 --> 00:33:37,120 Speaker 1: interact with us except through gravity. But you get enough 687 00:33:37,240 --> 00:33:42,000 Speaker 1: dark matter together under the densest conditions, maybe it's forming 688 00:33:42,080 --> 00:33:45,480 Speaker 1: a super fluid. And now we give it new properties 689 00:33:45,680 --> 00:33:48,120 Speaker 1: like those water balloons in the bucket. It can do 690 00:33:48,360 --> 00:33:50,640 Speaker 1: things when it's all together in those conditions that it 691 00:33:50,720 --> 00:33:53,640 Speaker 1: couldn't do otherwise. And the idea is that this new 692 00:33:53,680 --> 00:33:57,160 Speaker 1: super fluid state of dark matter might explain what's happening 693 00:33:57,320 --> 00:34:01,800 Speaker 1: inside galaxies that currently dark matter as a theory can't explain. 694 00:34:02,440 --> 00:34:05,640 Speaker 1: Interesting But I thought maybe dark matter didn't interact with itself. 695 00:34:05,800 --> 00:34:08,400 Speaker 1: So isn't it already a super fluid that doesn't have 696 00:34:08,400 --> 00:34:11,080 Speaker 1: any internal friction. Yeah, so currently we think that dark 697 00:34:11,120 --> 00:34:14,080 Speaker 1: matter doesn't have any any interactions. So you might think, oh, yeah, 698 00:34:14,120 --> 00:34:16,400 Speaker 1: dark matter out there in space is a collisionless fluid. 699 00:34:16,440 --> 00:34:19,200 Speaker 1: Isn't that also a super fluid, right, Not technically, because 700 00:34:19,200 --> 00:34:22,160 Speaker 1: they don't have overlapping wave functions. Like if you just 701 00:34:22,239 --> 00:34:24,840 Speaker 1: have a really dilute gas of dark matter, like we 702 00:34:24,880 --> 00:34:27,360 Speaker 1: think exists out there at the edge of the galaxy 703 00:34:27,480 --> 00:34:29,880 Speaker 1: and beyond, that's not really a super fluid because the 704 00:34:29,880 --> 00:34:31,960 Speaker 1: particles are just really far away from each other. To 705 00:34:32,000 --> 00:34:34,920 Speaker 1: have a super fluid have these new phenomena emerge, you 706 00:34:34,960 --> 00:34:36,879 Speaker 1: really have to have them close enough to each other, 707 00:34:37,080 --> 00:34:39,960 Speaker 1: so the wave functions overlap. So it's more about the 708 00:34:40,040 --> 00:34:44,520 Speaker 1: quantum overlap of the individual particles and less about the 709 00:34:44,600 --> 00:34:48,520 Speaker 1: kind of frictionless flow of the fluid for dark matter. Yeah, 710 00:34:48,560 --> 00:34:51,200 Speaker 1: And in this case, it's the overlap of those particles 711 00:34:51,200 --> 00:34:54,759 Speaker 1: that generates new phenomena like frictionless flow, and in the 712 00:34:54,760 --> 00:34:57,319 Speaker 1: case of dark matter super fluid, they think it can 713 00:34:57,400 --> 00:35:01,439 Speaker 1: effectively create a new force. What emerges from a dark 714 00:35:01,480 --> 00:35:03,760 Speaker 1: matter super fluid. It's sort of like a new force 715 00:35:03,960 --> 00:35:07,400 Speaker 1: which effectively can change the way that gravity works to 716 00:35:07,480 --> 00:35:10,080 Speaker 1: give you exactly the same behavior that we see in 717 00:35:10,120 --> 00:35:12,960 Speaker 1: the mond theory of dark matter. To me, the question 718 00:35:13,040 --> 00:35:16,400 Speaker 1: should be is dark matter a super duper fluid? All right, Well, 719 00:35:16,480 --> 00:35:19,200 Speaker 1: let's get into how dark matter being a super duper 720 00:35:19,200 --> 00:35:21,600 Speaker 1: fluid at the heart of galaxies could explain some of 721 00:35:21,600 --> 00:35:25,240 Speaker 1: the things we can understand or explain about the current 722 00:35:25,280 --> 00:35:28,640 Speaker 1: model of dark matter. But first let's take another quick break. 723 00:35:41,160 --> 00:35:43,520 Speaker 1: All right, we're asking the question could dark matter be 724 00:35:43,640 --> 00:35:46,000 Speaker 1: a super fluid? And we're asking the question because there 725 00:35:46,040 --> 00:35:49,400 Speaker 1: are things about dark matter that we can't quite explain. 726 00:35:49,880 --> 00:35:51,719 Speaker 1: I mean, we don't know what it is or what 727 00:35:51,840 --> 00:35:54,080 Speaker 1: it could be. But even our idea of it as 728 00:35:54,120 --> 00:35:56,439 Speaker 1: a particle, as a bit of matter, as bits of matter, 729 00:35:56,520 --> 00:35:58,560 Speaker 1: doesn't quite explain some of the things we see out 730 00:35:58,560 --> 00:36:00,200 Speaker 1: there in the universe. And so the idea is that 731 00:36:00,320 --> 00:36:03,120 Speaker 1: maybe dark matter is a super fluid, which might explain 732 00:36:03,160 --> 00:36:05,440 Speaker 1: these things. Yeah, and I think the kernel of the idea. 733 00:36:05,520 --> 00:36:08,400 Speaker 1: What generated it is noticing that dark matter as a 734 00:36:08,520 --> 00:36:12,880 Speaker 1: theory seems to have trouble in the densest situations. It 735 00:36:12,960 --> 00:36:16,919 Speaker 1: works really well between galaxy clusters, it works out there 736 00:36:16,920 --> 00:36:20,480 Speaker 1: in space for gravitational lensing of lots of galaxies. It 737 00:36:20,560 --> 00:36:23,800 Speaker 1: works in the early universe, but inside galaxy is currently 738 00:36:23,800 --> 00:36:26,520 Speaker 1: the densest places in the universe is where it struggles. 739 00:36:26,960 --> 00:36:30,200 Speaker 1: So people thought, well, maybe when dark matter gets denser, 740 00:36:30,280 --> 00:36:32,879 Speaker 1: it forms this new state, this super fluid, and then 741 00:36:32,920 --> 00:36:35,640 Speaker 1: we can figure out how to give this superfluid new properties. 742 00:36:35,760 --> 00:36:38,240 Speaker 1: Maybe you can solve the problems of dark matter inside 743 00:36:38,239 --> 00:36:41,399 Speaker 1: galaxies without breaking with dark matter is already so good 744 00:36:41,400 --> 00:36:44,320 Speaker 1: at explaining everywhere else, right, So the idea is that 745 00:36:44,360 --> 00:36:47,840 Speaker 1: it only forms a super fluid inside the dense environment 746 00:36:47,840 --> 00:36:50,440 Speaker 1: of a galaxy. Everywhere else it's just this normal, boring, 747 00:36:50,480 --> 00:36:53,759 Speaker 1: old dark matter, normal boring, but it's still quite mysterious 748 00:36:54,040 --> 00:36:57,279 Speaker 1: and elusive. They're saying that at the center of galaxies, 749 00:36:57,280 --> 00:37:00,440 Speaker 1: where things are pretty dense anyways, right, there are sometimes 750 00:37:00,440 --> 00:37:02,279 Speaker 1: black holes in the middle of galaxies. There are a 751 00:37:02,280 --> 00:37:05,000 Speaker 1: lot of stars clustered together. The ideas that maybe dark 752 00:37:05,040 --> 00:37:08,480 Speaker 1: matter is super duper compact at the center of galaxies 753 00:37:08,560 --> 00:37:11,200 Speaker 1: more so than like at the edges of galaxies, and 754 00:37:11,280 --> 00:37:13,920 Speaker 1: not just at the center, but yes, definitely denser at 755 00:37:13,920 --> 00:37:16,920 Speaker 1: the center. But essentially we're thinking about galaxies as like 756 00:37:16,960 --> 00:37:19,040 Speaker 1: a dense place in the universe. And as we talked 757 00:37:19,040 --> 00:37:21,480 Speaker 1: about earlier, how do you make a super fluid. You 758 00:37:21,520 --> 00:37:23,719 Speaker 1: need to get the particles close enough so their wave 759 00:37:23,760 --> 00:37:27,160 Speaker 1: functions overlapped and make the super fluid thing happen. And 760 00:37:27,200 --> 00:37:29,520 Speaker 1: so that can happen in a galaxy because there's a 761 00:37:29,520 --> 00:37:32,160 Speaker 1: lot of gravity there, it gathers together a lot of 762 00:37:32,239 --> 00:37:34,719 Speaker 1: dark matter. Another trick they pull is to make dark 763 00:37:34,760 --> 00:37:38,520 Speaker 1: matter very very very very low mass. We know like 764 00:37:38,760 --> 00:37:41,480 Speaker 1: how much mass the dark matter we need, but we 765 00:37:41,480 --> 00:37:44,640 Speaker 1: don't know how much mass each particle has. So if 766 00:37:44,640 --> 00:37:47,520 Speaker 1: you make dark matter out of really massive particles, you 767 00:37:47,560 --> 00:37:49,920 Speaker 1: have fewer of them. If you make dark matter out 768 00:37:49,960 --> 00:37:53,000 Speaker 1: of really low mass particles, you need more of them. 769 00:37:53,040 --> 00:37:54,839 Speaker 1: So the folks who are working on this theory say 770 00:37:55,000 --> 00:37:57,120 Speaker 1: that dark matter is really really low mass, then there's 771 00:37:57,160 --> 00:38:00,680 Speaker 1: a huge number of them, right, And so they're imagining 772 00:38:00,719 --> 00:38:04,400 Speaker 1: the centers of galaxies being swarmed with zillions and zillions 773 00:38:04,440 --> 00:38:07,799 Speaker 1: of very very low mass dark matter particles. That come 774 00:38:07,880 --> 00:38:10,319 Speaker 1: together into a super fluid, and when they do that, 775 00:38:10,400 --> 00:38:13,400 Speaker 1: they get all sorts of new weird behaviors. Cool, well, 776 00:38:13,440 --> 00:38:15,640 Speaker 1: it's getting too a little bit of what those behaviors are, Like, 777 00:38:15,680 --> 00:38:17,840 Speaker 1: what do you think happens when dark matter is that 778 00:38:17,880 --> 00:38:20,719 Speaker 1: close together that the wave funtionings overlap. So it's really 779 00:38:20,719 --> 00:38:23,239 Speaker 1: hard to do these calculations because you're talking about like 780 00:38:23,320 --> 00:38:26,279 Speaker 1: overlapping wave functions of lots and lots and lots and 781 00:38:26,320 --> 00:38:28,520 Speaker 1: lots of particles. So when physics needs to do that, 782 00:38:28,560 --> 00:38:30,680 Speaker 1: they try to describe these new behaviors in terms of 783 00:38:30,719 --> 00:38:33,080 Speaker 1: something they're already familiar with. So the way they usually 784 00:38:33,080 --> 00:38:37,040 Speaker 1: talk about it is in terms of sound waves propagating 785 00:38:37,200 --> 00:38:40,600 Speaker 1: through this super fluid. I think about like shock waves 786 00:38:40,680 --> 00:38:43,439 Speaker 1: moving through it. How if you pull on one part 787 00:38:43,440 --> 00:38:45,160 Speaker 1: of it that would affect the other parts of it. 788 00:38:45,239 --> 00:38:47,239 Speaker 1: And dark matter is this super fluid, so it's like 789 00:38:47,600 --> 00:38:50,600 Speaker 1: weirdly tightly couple that acts like a big coherent blob 790 00:38:50,840 --> 00:38:53,920 Speaker 1: instead of individual pieces. And so they talk about phonons, 791 00:38:53,920 --> 00:38:56,480 Speaker 1: which are like sound waves moving through this super fluid, 792 00:38:56,640 --> 00:38:59,399 Speaker 1: and they build up this whole theory which comes out 793 00:38:59,520 --> 00:39:02,399 Speaker 1: looking a new force sort of like this dark matter 794 00:39:02,400 --> 00:39:04,399 Speaker 1: when it enters this super fluid as a new way 795 00:39:04,400 --> 00:39:07,560 Speaker 1: to interact with itself that it didn't have before. Well, 796 00:39:07,680 --> 00:39:09,759 Speaker 1: I guess maybe one thing that's confusing me is that 797 00:39:09,840 --> 00:39:12,319 Speaker 1: I thought dark matter didn't interact with itself, right like 798 00:39:12,360 --> 00:39:15,280 Speaker 1: it The particles of dark matter don't usually or can't 799 00:39:15,400 --> 00:39:18,640 Speaker 1: bump into themselves. That's what was part of the idea 800 00:39:18,680 --> 00:39:21,399 Speaker 1: of dark matter. So why would bring them together really 801 00:39:21,440 --> 00:39:24,160 Speaker 1: close together make them interact in a different way. But 802 00:39:24,200 --> 00:39:26,520 Speaker 1: if they can't interact with each other, you're right, at 803 00:39:26,520 --> 00:39:28,760 Speaker 1: a particle level, they don't have that kind of interaction. 804 00:39:28,840 --> 00:39:31,759 Speaker 1: We're only talking about gravity, but now we're adding other 805 00:39:31,840 --> 00:39:35,200 Speaker 1: weird quantum effects, and quantum effects when they all work together, 806 00:39:35,440 --> 00:39:37,800 Speaker 1: can make it feel like there's a force. Another example 807 00:39:37,880 --> 00:39:40,680 Speaker 1: is the poly exclusion principle. As someone that tells you that, 808 00:39:40,760 --> 00:39:43,920 Speaker 1: like two fermions can't be in the same location. That's 809 00:39:43,960 --> 00:39:46,880 Speaker 1: the thing that keeps some kinds of stars from collapsing. 810 00:39:47,160 --> 00:39:50,120 Speaker 1: It allows you to resist the force of gravity is 811 00:39:50,160 --> 00:39:52,879 Speaker 1: trying to push it in. It's not technically a force 812 00:39:52,920 --> 00:39:55,520 Speaker 1: at the particle level, there's no force there, but this 813 00:39:55,640 --> 00:39:59,440 Speaker 1: quantum behavior of the objects basically acts as a block 814 00:39:59,560 --> 00:40:03,120 Speaker 1: to g so in the same way, this weird quantum 815 00:40:03,160 --> 00:40:06,200 Speaker 1: behavior of dark matter when it's a super fluid acts 816 00:40:06,320 --> 00:40:09,200 Speaker 1: sort of in a way to change gravity. It's sort 817 00:40:09,200 --> 00:40:11,799 Speaker 1: of like there's a new force. It's not an individual 818 00:40:11,840 --> 00:40:15,240 Speaker 1: new force on the particles. It's a way to describe 819 00:40:15,440 --> 00:40:17,600 Speaker 1: what happens to all these particles when they do this 820 00:40:17,680 --> 00:40:20,400 Speaker 1: new quantum thing. You can tell a story about it 821 00:40:20,440 --> 00:40:23,279 Speaker 1: as if it was a new force. Okay, I think 822 00:40:23,320 --> 00:40:25,160 Speaker 1: maybe I'm starting to get it. Like if I have 823 00:40:25,280 --> 00:40:28,319 Speaker 1: two particles of dark matter, and I have them really 824 00:40:28,360 --> 00:40:30,719 Speaker 1: far apart, then they do interact with each other, and 825 00:40:30,800 --> 00:40:33,239 Speaker 1: not like they can't bump into each other, but they 826 00:40:33,280 --> 00:40:36,680 Speaker 1: can attract each other gravitationally, like there's a gravitational force 827 00:40:36,719 --> 00:40:39,239 Speaker 1: between the two particles of dark matter. I think what 828 00:40:39,280 --> 00:40:41,279 Speaker 1: you're saying is when you bring them really really close 829 00:40:41,320 --> 00:40:43,279 Speaker 1: to each other, so that wave function of these two 830 00:40:43,400 --> 00:40:46,640 Speaker 1: dark matter particles starts overlap, then there are other effects 831 00:40:46,640 --> 00:40:50,160 Speaker 1: that start to kick in, other quantum effects then maybe 832 00:40:50,200 --> 00:40:53,520 Speaker 1: affect the gravity between them. Yeah, that's precisely it. And 833 00:40:53,600 --> 00:40:55,759 Speaker 1: you can talk about those new quantum effects as a 834 00:40:55,840 --> 00:40:59,839 Speaker 1: new force and introduce even like new particles for that force. 835 00:41:00,080 --> 00:41:02,880 Speaker 1: Call these things phone ons, or you could just say, 836 00:41:03,000 --> 00:41:07,440 Speaker 1: maybe that changes the overall effective gravity, right, it changes 837 00:41:07,719 --> 00:41:10,080 Speaker 1: the impact of gravity because now you have to factor 838 00:41:10,080 --> 00:41:12,560 Speaker 1: in this new, weird quantum effect. And the amazing thing 839 00:41:12,640 --> 00:41:14,600 Speaker 1: that comes out of the math is that the change 840 00:41:14,600 --> 00:41:17,080 Speaker 1: it makes to gravity is to make it look exactly 841 00:41:17,160 --> 00:41:21,680 Speaker 1: like Mond predicts. Remember, Mind, is this change in Newtonian 842 00:41:21,719 --> 00:41:25,080 Speaker 1: gravity that would beautifully describe everything we see at the 843 00:41:25,120 --> 00:41:28,000 Speaker 1: hearts of galaxies, but fails everywhere else. It turns out 844 00:41:28,040 --> 00:41:30,800 Speaker 1: if you make dark matter of super fluid, it changes 845 00:41:30,880 --> 00:41:33,439 Speaker 1: the gravity within this dark matter to make it look 846 00:41:33,520 --> 00:41:35,719 Speaker 1: just like Mind. But wait, I thought that you know 847 00:41:35,840 --> 00:41:38,960 Speaker 1: the gravity The gravity is just between the two particles, right, 848 00:41:39,000 --> 00:41:42,000 Speaker 1: Like the gravity between these two dark matter particles maybe 849 00:41:42,080 --> 00:41:44,600 Speaker 1: changes when you bring them closer together, so that maybe 850 00:41:44,600 --> 00:41:47,560 Speaker 1: they feel or not feel more or less gravity. But 851 00:41:47,880 --> 00:41:51,120 Speaker 1: to someone standing far away from these two particles, why 852 00:41:51,160 --> 00:41:53,480 Speaker 1: would they why would the gravity change for them? No, 853 00:41:53,600 --> 00:41:55,760 Speaker 1: it doesn't. You're absolutely right. And so if you're outside 854 00:41:55,760 --> 00:41:58,439 Speaker 1: of a galaxy, it doesn't matter whether the dark matter 855 00:41:58,520 --> 00:42:01,560 Speaker 1: is fluid or not. But we're talking about inside of galaxy. 856 00:42:01,600 --> 00:42:04,759 Speaker 1: We're talking about what's happening internally, how fast things are 857 00:42:04,760 --> 00:42:08,120 Speaker 1: spinning the gravity that like one blob of dark matter 858 00:42:08,200 --> 00:42:10,560 Speaker 1: is feeling on another blob of dark matter inside the 859 00:42:10,600 --> 00:42:14,520 Speaker 1: same galaxy. So this affects how dark matter inside the 860 00:42:14,520 --> 00:42:16,959 Speaker 1: Milky Way, for example, is pulling on other dark matter 861 00:42:17,040 --> 00:42:19,480 Speaker 1: inside the Milky Way, which is exactly what keeps the 862 00:42:19,480 --> 00:42:23,800 Speaker 1: whole galaxy together as it spins. So these quantum effects 863 00:42:24,000 --> 00:42:27,480 Speaker 1: make the gravity stronger of the superfluid or weaker. It 864 00:42:27,520 --> 00:42:30,960 Speaker 1: makes the gravity stronger, right, enhances their gravity. What do 865 00:42:31,000 --> 00:42:33,040 Speaker 1: you mean, like, do you know what the quantum effect 866 00:42:33,120 --> 00:42:35,359 Speaker 1: is or are just kind of postulating that there's maybe 867 00:42:35,440 --> 00:42:38,920 Speaker 1: some quantum effect that would make the gravity stronger. The 868 00:42:38,960 --> 00:42:41,799 Speaker 1: quantum effect comes from these overlapping wave functions, and when 869 00:42:41,800 --> 00:42:43,880 Speaker 1: you put it together and you do the math, and 870 00:42:43,920 --> 00:42:46,759 Speaker 1: you squeeze it theoretically sort of into the box of 871 00:42:46,760 --> 00:42:49,040 Speaker 1: a force and say, how do I interpret this as 872 00:42:49,080 --> 00:42:52,360 Speaker 1: a force. Then the calculations come out to predict a 873 00:42:52,440 --> 00:42:55,279 Speaker 1: change in the force of gravity that looks just like 874 00:42:55,360 --> 00:42:58,080 Speaker 1: the math you get from Mond. It's not just speculation. 875 00:42:58,360 --> 00:43:01,319 Speaker 1: You can go directly from these quantum effects to calculating 876 00:43:01,560 --> 00:43:04,359 Speaker 1: the new effective force of gravity, and it looks just 877 00:43:04,480 --> 00:43:07,360 Speaker 1: like Mon's prediction, which is as we know something that 878 00:43:07,400 --> 00:43:09,759 Speaker 1: works very very well well. But I think what you're 879 00:43:09,760 --> 00:43:12,840 Speaker 1: saying is that the super compact dark matter forms a 880 00:43:12,880 --> 00:43:17,360 Speaker 1: super fluid which has stronger gravity between the dark matter 881 00:43:17,400 --> 00:43:20,040 Speaker 1: particles that are in the super fluid. But with something 882 00:43:20,080 --> 00:43:23,040 Speaker 1: outside of the super fluid, would it feel this extra 883 00:43:23,080 --> 00:43:25,880 Speaker 1: gravity or not? Well, something inside the galaxy would, but 884 00:43:25,960 --> 00:43:30,040 Speaker 1: something outside the galaxy wouldn't. Right, So something outside far 885 00:43:30,120 --> 00:43:32,919 Speaker 1: far away other galaxies in the cluster wouldn't feel any 886 00:43:33,040 --> 00:43:35,480 Speaker 1: change in the effective gravity. And that's key because we 887 00:43:35,480 --> 00:43:37,600 Speaker 1: don't want to change the predictions for dark matter in 888 00:43:37,600 --> 00:43:40,640 Speaker 1: the cluster that already works really really well. The way 889 00:43:40,640 --> 00:43:43,640 Speaker 1: we see the galaxies rotate around each other, and big 890 00:43:43,640 --> 00:43:46,919 Speaker 1: clusters of galaxies rotate around other clusters of galaxies. That's 891 00:43:47,080 --> 00:43:49,600 Speaker 1: very well described by the dark matter theory. So we 892 00:43:49,600 --> 00:43:52,000 Speaker 1: don't want to change that. So the super fluid thing 893 00:43:52,040 --> 00:43:55,600 Speaker 1: only changes what happens inside galaxies, not between galaxies. And 894 00:43:55,600 --> 00:43:57,960 Speaker 1: so how would that explain what we talked about earlier 895 00:43:58,040 --> 00:44:00,359 Speaker 1: was one of the shortcomings of dark matter, which is 896 00:44:00,360 --> 00:44:03,000 Speaker 1: that the proportion of dark matter and regular matter is 897 00:44:03,040 --> 00:44:07,080 Speaker 1: too consistent between galaxies. How would this explain it? Well? Conceptually, 898 00:44:07,120 --> 00:44:09,080 Speaker 1: you can imagine that it gives us away for like 899 00:44:09,160 --> 00:44:11,200 Speaker 1: dark matter and normal matters sort of talk to each 900 00:44:11,200 --> 00:44:14,720 Speaker 1: other more intimately, so effectively it solves a problem by saying, 901 00:44:15,160 --> 00:44:17,399 Speaker 1: you do still have some variation in how much dark 902 00:44:17,440 --> 00:44:20,280 Speaker 1: matter and normal matter you have, but dark matter itself 903 00:44:20,320 --> 00:44:23,720 Speaker 1: acts a little bit differently, so it changes how galaxies rotated, 904 00:44:23,800 --> 00:44:27,239 Speaker 1: changes the effective gravity of that dark matter, and that's 905 00:44:27,280 --> 00:44:30,680 Speaker 1: what determines how fast a galaxy can rotate without tearing 906 00:44:30,680 --> 00:44:33,160 Speaker 1: itself apart. And remember the discrepancy we saw it was 907 00:44:33,200 --> 00:44:36,239 Speaker 1: not actually directly in the dark matter density of these galaxies, 908 00:44:36,239 --> 00:44:39,920 Speaker 1: but the rotation speed of the galaxies versus their brightness. 909 00:44:40,239 --> 00:44:42,399 Speaker 1: So now we have a new way for dark matter 910 00:44:42,440 --> 00:44:44,839 Speaker 1: and normal matter to side interact a little bit more 911 00:44:44,920 --> 00:44:48,120 Speaker 1: strongly because this new force that's inside the dark matter 912 00:44:48,160 --> 00:44:50,440 Speaker 1: super fluid, because we think that's sort of like couples 913 00:44:50,800 --> 00:44:53,600 Speaker 1: the stars and the dark matter a little bit more tightly, 914 00:44:53,960 --> 00:44:56,160 Speaker 1: makes it possible for them to have like more feedback 915 00:44:56,200 --> 00:44:59,400 Speaker 1: mechanisms to potentially explain what we're seeing out there in 916 00:44:59,400 --> 00:45:01,440 Speaker 1: the universe. I think what you're saying is that maybe 917 00:45:01,480 --> 00:45:04,360 Speaker 1: there's like an extra effect here that comes from the 918 00:45:04,400 --> 00:45:09,440 Speaker 1: super fluidity of dark matter that maybe makes it not random, right, 919 00:45:09,440 --> 00:45:12,480 Speaker 1: because before the problem was that we expected the ratio 920 00:45:12,520 --> 00:45:14,320 Speaker 1: of dark matter and normal matter to be is a 921 00:45:14,400 --> 00:45:17,200 Speaker 1: little bit more random, more variation. But maybe this special 922 00:45:17,200 --> 00:45:19,520 Speaker 1: effects kind of acts in a way that gives you 923 00:45:19,600 --> 00:45:22,440 Speaker 1: less variation. Like if you have more dark matter, it 924 00:45:22,520 --> 00:45:24,400 Speaker 1: acts in a way so that you have more regular 925 00:45:24,480 --> 00:45:26,879 Speaker 1: matter as well. And if you have less dark matter, 926 00:45:26,960 --> 00:45:28,839 Speaker 1: then maybe acts in a way to give you less 927 00:45:28,880 --> 00:45:31,680 Speaker 1: regular matter. That's the kind of feedback effect we're looking for. 928 00:45:32,040 --> 00:45:34,360 Speaker 1: We see out there in the universe, this is strangely 929 00:45:34,440 --> 00:45:37,399 Speaker 1: tight relationship between the dark matter and the normal matter. 930 00:45:37,680 --> 00:45:40,440 Speaker 1: We didn't understand that if the only relationship between the 931 00:45:40,440 --> 00:45:43,480 Speaker 1: two was this fairly weak gravity. But if gravity gets 932 00:45:43,480 --> 00:45:46,279 Speaker 1: a little bit stronger, it helps solve those problems. And 933 00:45:46,320 --> 00:45:50,279 Speaker 1: more specifically, we see that the effective gravity inside these 934 00:45:50,280 --> 00:45:54,279 Speaker 1: galaxies now follows exactly the prediction of mind, which, as 935 00:45:54,280 --> 00:45:57,600 Speaker 1: we said before, predicts very precisely the ratio of these 936 00:45:57,680 --> 00:46:00,600 Speaker 1: dark matter to normal matter inside the galaxy. So it 937 00:46:00,640 --> 00:46:04,560 Speaker 1: all clicks very nicely into place. M M. It seems 938 00:46:04,600 --> 00:46:07,800 Speaker 1: like a pretty super idea. This is a super fluid, 939 00:46:08,200 --> 00:46:10,120 Speaker 1: but it also sort of constrains dark matter in a 940 00:46:10,120 --> 00:46:13,960 Speaker 1: bit right like it it depends also, like it can 941 00:46:14,040 --> 00:46:16,600 Speaker 1: only be a super fluid if dark matter is made 942 00:46:16,600 --> 00:46:19,640 Speaker 1: out of really light small particles, right, And there are 943 00:46:19,760 --> 00:46:22,279 Speaker 1: ideas out there for dark matter to be very very 944 00:46:22,360 --> 00:46:24,880 Speaker 1: light particles. The most common idea is a whimp, a 945 00:46:24,920 --> 00:46:28,640 Speaker 1: weekly interacting massive particle where the mass of the particle 946 00:46:28,680 --> 00:46:31,120 Speaker 1: would be like a hundred times the mass of the proton. 947 00:46:31,560 --> 00:46:33,799 Speaker 1: But there are other ideas where dark matter could be 948 00:46:33,880 --> 00:46:36,600 Speaker 1: very very light. We've talked about it before on the podcast, 949 00:46:36,760 --> 00:46:39,160 Speaker 1: the idea of an axion sort of like a photon 950 00:46:39,200 --> 00:46:41,520 Speaker 1: with a little bit of mass to it, And so 951 00:46:41,600 --> 00:46:43,560 Speaker 1: this idea is a little bit more like an axion 952 00:46:43,760 --> 00:46:46,600 Speaker 1: than a whimp, which would also maybe make dark matter 953 00:46:46,719 --> 00:46:51,040 Speaker 1: harder to eventually detect and study right directly, Yeah, a 954 00:46:51,080 --> 00:46:54,279 Speaker 1: lot of our searches for dark batters, these big underground 955 00:46:54,320 --> 00:46:56,680 Speaker 1: tanks that are looking for a dark matter particle to 956 00:46:56,719 --> 00:46:59,399 Speaker 1: come and bounce off a zenon atom for example, are 957 00:46:59,480 --> 00:47:03,040 Speaker 1: not will of sensing dark matter and very very low mass. 958 00:47:03,200 --> 00:47:05,879 Speaker 1: But we have other experiments that are looking for very 959 00:47:05,960 --> 00:47:08,319 Speaker 1: very low mass dark matter particles. But there are also 960 00:47:08,360 --> 00:47:11,040 Speaker 1: other ways to test this theory. People think that if 961 00:47:11,080 --> 00:47:15,080 Speaker 1: this is true, it will also affect like how galaxies merge. 962 00:47:15,360 --> 00:47:17,920 Speaker 1: I mean, if you have two merging galaxies and they 963 00:47:17,960 --> 00:47:21,120 Speaker 1: each have their own halo of dark matter, then what 964 00:47:21,239 --> 00:47:24,400 Speaker 1: happens when they emerge. You will see the super fluidity 965 00:47:24,440 --> 00:47:27,480 Speaker 1: effect because the halos won't merge as fast as they 966 00:47:27,520 --> 00:47:30,640 Speaker 1: would otherwise. Like two halos made of a normal fluid, 967 00:47:30,760 --> 00:47:33,359 Speaker 1: you'll expect a little bit of friction. Two halos made 968 00:47:33,360 --> 00:47:36,439 Speaker 1: of a super fluid, they'll basically pass through each other 969 00:47:36,760 --> 00:47:38,839 Speaker 1: and it'll be gravity that pulls them back, so they 970 00:47:38,840 --> 00:47:42,239 Speaker 1: would like oscillate more times as they merge. If it's 971 00:47:42,239 --> 00:47:45,120 Speaker 1: a super fluid, then if it's just a fluid, So 972 00:47:45,120 --> 00:47:47,959 Speaker 1: if we can like study merging galaxies as a chance, 973 00:47:48,040 --> 00:47:50,720 Speaker 1: we can see whether dark matter is a super fluid 974 00:47:51,040 --> 00:47:54,680 Speaker 1: or a normal fluid. I think we're saying is that 975 00:47:54,800 --> 00:47:57,680 Speaker 1: the dark matter at the outsides and the edges of 976 00:47:57,680 --> 00:48:00,720 Speaker 1: the galaxy, which is not as compact or super fluid, 977 00:48:00,760 --> 00:48:03,520 Speaker 1: would sort of become a superfluid once it crashes into 978 00:48:03,520 --> 00:48:06,480 Speaker 1: another galaxy. I'm saying that we can test the super 979 00:48:06,480 --> 00:48:09,640 Speaker 1: fluidity of dark matter by slamming into another blob of 980 00:48:09,680 --> 00:48:12,280 Speaker 1: super fluid. Dark matter, if it really is super fluid, 981 00:48:12,320 --> 00:48:15,560 Speaker 1: should basically pass right through. If it isn't super fluid, 982 00:48:15,640 --> 00:48:18,160 Speaker 1: then we should see some friction between the two blobs 983 00:48:18,200 --> 00:48:20,400 Speaker 1: of dark matter. And we can't do this very easily, 984 00:48:20,440 --> 00:48:25,000 Speaker 1: but sometimes galaxies collide, right, huge galaxies slam into other galaxies, 985 00:48:25,200 --> 00:48:29,640 Speaker 1: basically testing this hypothesis, doing this experiment of slamming one 986 00:48:29,680 --> 00:48:32,000 Speaker 1: blob of dark matter into another. So if we can 987 00:48:32,040 --> 00:48:34,160 Speaker 1: study those collisions, we might be able to tell the 988 00:48:34,200 --> 00:48:38,080 Speaker 1: difference between super fluid collisions and normal fluid collisions because 989 00:48:38,120 --> 00:48:40,400 Speaker 1: they should look a little bit different. Pretty interesting to 990 00:48:40,440 --> 00:48:44,080 Speaker 1: think that dark matter, which we can see or touch, 991 00:48:44,280 --> 00:48:47,480 Speaker 1: could be doing things that we can maybe imagine and 992 00:48:47,560 --> 00:48:50,120 Speaker 1: even the dunk right and figure out, yeah, because we 993 00:48:50,160 --> 00:48:52,080 Speaker 1: can't see the dark matter directly, but we can see 994 00:48:52,080 --> 00:48:55,160 Speaker 1: it indirectly because of gravitational lensing and because of its 995 00:48:55,200 --> 00:48:58,160 Speaker 1: impact on the other stars. So doing a lot of 996 00:48:58,160 --> 00:49:00,959 Speaker 1: statistics and very careful measurements, we can get a sense 997 00:49:01,000 --> 00:49:03,120 Speaker 1: for where the dark matter is and what's happened to it. 998 00:49:03,360 --> 00:49:05,520 Speaker 1: And then we can check that against our calculations and 999 00:49:05,560 --> 00:49:07,880 Speaker 1: see does it look like it's being a superfluid or 1000 00:49:07,920 --> 00:49:10,239 Speaker 1: a normal fluid? Right, And if you see that it 1001 00:49:10,280 --> 00:49:11,960 Speaker 1: has a cape on it, then you know, like Hey, 1002 00:49:12,000 --> 00:49:14,719 Speaker 1: it definitely has superpowers, right, that's right, And then it 1003 00:49:14,760 --> 00:49:16,799 Speaker 1: needs to stop by our food truck so we can 1004 00:49:16,840 --> 00:49:20,600 Speaker 1: promote our super fluid beverages, which we has not quite 1005 00:49:20,640 --> 00:49:24,719 Speaker 1: passed the p d A approval. Right, that's right. Don't 1006 00:49:24,719 --> 00:49:27,239 Speaker 1: go at drinking any super fluid yet, please people. Yeah, 1007 00:49:27,360 --> 00:49:29,600 Speaker 1: and don't invite Daniel to your lab because he will 1008 00:49:29,640 --> 00:49:34,719 Speaker 1: definitely put his own super fluids on everything. Hey, I'm 1009 00:49:34,719 --> 00:49:36,960 Speaker 1: a curious person. What can I say? All right, Well, 1010 00:49:37,000 --> 00:49:39,960 Speaker 1: another interesting idea about dark matter, the one that could 1011 00:49:39,960 --> 00:49:43,000 Speaker 1: explain what is going on out there, and another example 1012 00:49:43,040 --> 00:49:45,479 Speaker 1: of how this is still work in progress. We don't 1013 00:49:45,480 --> 00:49:47,680 Speaker 1: know what this thing is. We're trying to figure it out, 1014 00:49:47,880 --> 00:49:50,239 Speaker 1: and there are still new ideas coming up that could 1015 00:49:50,280 --> 00:49:53,880 Speaker 1: explain what's going on. Yeah, there are whole categories of ideas. 1016 00:49:53,960 --> 00:49:56,160 Speaker 1: Some of them even try to combine dark matter with 1017 00:49:56,400 --> 00:49:59,280 Speaker 1: mond and say, maybe dark matter is real but also 1018 00:49:59,360 --> 00:50:02,080 Speaker 1: gravity and used to be modified. Lots of people out 1019 00:50:02,120 --> 00:50:04,239 Speaker 1: there trying to make the best of both worlds, and 1020 00:50:04,280 --> 00:50:06,800 Speaker 1: this is like a cool alternative to try to capture 1021 00:50:07,160 --> 00:50:09,200 Speaker 1: all of the best bits of all of those theories. 1022 00:50:09,600 --> 00:50:12,680 Speaker 1: You could make a dark Mond to the theory, right, Yeah, 1023 00:50:12,680 --> 00:50:14,719 Speaker 1: and we could have a dark mond flavored coke. There 1024 00:50:14,760 --> 00:50:17,880 Speaker 1: you go, and you can make a dark Mont Sunday 1025 00:50:17,880 --> 00:50:20,719 Speaker 1: ice cream Sunday as well. All right, well, we hope 1026 00:50:20,719 --> 00:50:23,960 Speaker 1: you enjoyed that. Thanks for joining us, see you next time. 1027 00:50:31,760 --> 00:50:34,600 Speaker 1: Thanks for listening, and remember that Daniel and Jorge explained. 1028 00:50:34,600 --> 00:50:37,480 Speaker 1: The Universe is a production of I heart Radio. For 1029 00:50:37,640 --> 00:50:40,560 Speaker 1: more podcast from my heart Radio, visit the i heart 1030 00:50:40,640 --> 00:50:44,239 Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your 1031 00:50:44,280 --> 00:50:50,640 Speaker 1: favorite shows. Ye