WEBVTT - A discounted dark matter discovery 0:00:08.480 --> 0:00:11.559 Hey, Daniel, as a particle physicist, what's the one thing 0:00:11.680 --> 0:00:14.760 you would most like to discover? If I could pick 0:00:14.880 --> 0:00:17.840 just one thing to discover? Yeah, like go wild? What's 0:00:17.880 --> 0:00:20.959 your biggest scientific ambition. Well that's a great question, but 0:00:21.120 --> 0:00:23.360 it's not actually that hard to pick. I would want 0:00:23.400 --> 0:00:27.080 to discover dark matter because it's such a big mystery. Yeah, 0:00:27.080 --> 0:00:30.160 it's one of the biggest open questions in modern science, 0:00:30.200 --> 0:00:32.919 and I personally really want to know the answer. Right, 0:00:32.960 --> 0:00:35.319 But here's a catch. What have you discovered what it is? 0:00:35.560 --> 0:00:39.480 But nobody believes you? Are you still interested? Oh? Man, 0:00:39.600 --> 0:00:43.280 like a modern day physics Cassandra. That sounds a little 0:00:43.280 --> 0:00:45.560 bit like torture. But you know, as long as I 0:00:45.640 --> 0:00:48.240 know the answer to the questions about the universe, I 0:00:48.280 --> 0:00:50.360 would still want to find out. So it's all about you. 0:00:51.880 --> 0:01:09.959 Science is personal. Hi am or handmade cartoonists and the 0:01:10.000 --> 0:01:13.200 creator of PhD comment. Hi, I'm Daniel. I'm a particle 0:01:13.240 --> 0:01:17.160 physicist and I'm desperately seeking dark matter. How desperate are you, Daniel? 0:01:17.360 --> 0:01:20.440 Not desperate enough to make up my data, but desperate 0:01:20.520 --> 0:01:23.119 enough to consider almost anything. You're desperate enough to move 0:01:23.160 --> 0:01:26.320 to Italy maybe to do your research. I do like 0:01:26.440 --> 0:01:29.160 that black pasta to have over there, so called that 0:01:29.240 --> 0:01:34.000 dark matter. Than yeah, it's called squid in tasta. Well 0:01:34.000 --> 0:01:38.040 they've discovered something delicious at the very least. But welcome 0:01:38.040 --> 0:01:40.440 to our podcast Daniel and Jorge Explain the Universe, a 0:01:40.560 --> 0:01:43.039 production of our Heart Radio in which we take a 0:01:43.080 --> 0:01:47.040 bite out of the tastiest intellectual questions of the universe. 0:01:47.160 --> 0:01:50.640 We true, we swallow. We explain all of it to you. Sorry, 0:01:50.680 --> 0:01:53.240 we serve it up on a dish and hope that 0:01:53.320 --> 0:01:55.559 you slurp it all up so you can think about 0:01:55.600 --> 0:01:58.440 the universe and everything in it. Because everything about the 0:01:58.520 --> 0:02:01.600 universe is wondrous and hazing, and it makes us curious. 0:02:01.640 --> 0:02:04.080 But it doesn't just make scientists curious. We think it 0:02:04.120 --> 0:02:08.040 makes everybody curious. That curiosity is wonderful and we want 0:02:08.080 --> 0:02:10.920 to cherish it and satisfy it by explaining to you 0:02:11.080 --> 0:02:13.520 some of the mysteries of the universe. And there are 0:02:13.560 --> 0:02:15.720 still a lot of mysteries out there. There are big 0:02:15.840 --> 0:02:18.120 chunks of the universe we don't know anything about, and 0:02:18.160 --> 0:02:21.359 there are big questions about the very nature of our 0:02:21.400 --> 0:02:24.840 cosmos and where we came from, and also what is 0:02:25.000 --> 0:02:28.119 even in it. That's right, Recently, scientists have cracked open 0:02:28.160 --> 0:02:30.239 the universe and discovered that there's a lot of stuff 0:02:30.280 --> 0:02:32.919 out there that we don't know, that we don't understand. 0:02:32.960 --> 0:02:35.680 There are new kinds of stuff out there, and it 0:02:35.720 --> 0:02:39.000 makes us desperately curious. What is it? Why is it? 0:02:39.120 --> 0:02:41.280 Why is there so much more of it than our 0:02:41.440 --> 0:02:44.720 kind of stuff? So many questions, so few answers. And 0:02:44.880 --> 0:02:48.080 is it delicious? Also? It's a big question, and everybody's fine, 0:02:48.120 --> 0:02:49.840 how much of it should you have on top of 0:02:49.840 --> 0:02:52.280 your pasta? And can you put cheese on it? Are 0:02:52.320 --> 0:02:55.280 there rules for what you can put parmes on cheese on? Absolutely, 0:02:55.320 --> 0:02:57.720 you can put parmesan cheese on everything. That's the rule, 0:02:57.800 --> 0:03:00.000 even sea food pasta. I feel like that's an unstage 0:03:00.000 --> 0:03:03.840 it a rule that's a whole other podcast episode. We 0:03:03.840 --> 0:03:05.639 can't get into that today. Man, We have to stay 0:03:05.639 --> 0:03:10.320 on topic seafood matter, seafood matters. But anyways, a big 0:03:10.360 --> 0:03:12.960 bite of the universe that we don't know anything about 0:03:13.360 --> 0:03:16.960 is a big mystery called dark matter. Of all of 0:03:17.000 --> 0:03:19.440 the energy and matter in the universe is something called 0:03:19.520 --> 0:03:21.880 dark matter, but we don't know what it is, and 0:03:21.919 --> 0:03:23.920 we would love to understand it. We would love to 0:03:23.960 --> 0:03:26.480 break it apart and figure out isn't made out of 0:03:26.520 --> 0:03:29.280 some tiny little particle we've never seen before. Is it 0:03:29.400 --> 0:03:32.280 lots of different particles? Is it something else which isn't 0:03:32.320 --> 0:03:35.520 even a particle. So physicists all over the world are 0:03:35.560 --> 0:03:38.520 using lots of different techniques to try to isolate dark 0:03:38.560 --> 0:03:41.400 matter and figure out what kind of particle it is. Yeah, 0:03:41.440 --> 0:03:44.440 because it's sweating all around us, right like it's it's everywhere. 0:03:44.560 --> 0:03:47.080 In fact, probably when you eat pasta you are taking 0:03:47.120 --> 0:03:50.240 big bite fools of dark matter at the same time. 0:03:50.600 --> 0:03:52.840 That's right, but fortunately your body doesn't digest it, so 0:03:52.880 --> 0:03:56.200 you don't gain all of that mass. But yes, dark matter, 0:03:56.320 --> 0:03:59.320 we think is all around us. It's part of the universe, 0:03:59.360 --> 0:04:02.520 but it's not. And evenly through the universe it's clumped together, 0:04:02.920 --> 0:04:05.800 just like our matter. So we think that our galaxy 0:04:05.880 --> 0:04:09.440 is swimming in a massive halo of dark matter, and 0:04:09.480 --> 0:04:12.720 that the Earth is flying through a wind of dark matter. 0:04:13.200 --> 0:04:15.880 And so physicists are using lots of techniques to try 0:04:15.880 --> 0:04:18.680 to discover this, looking at it colliding with itself in 0:04:18.720 --> 0:04:21.120 the center of the galaxy. We're trying to make it 0:04:21.160 --> 0:04:25.159 in underground collisions at the Large Hadron collider and also 0:04:25.240 --> 0:04:28.120 we're trying to detect this dark matter wind. Yeah, everybody 0:04:28.160 --> 0:04:30.000 seems to be looking for it, but it's really hard 0:04:30.000 --> 0:04:33.480 because you can't touch it or see it, and so 0:04:33.520 --> 0:04:36.960 far nobody has really got in a chest to figure 0:04:36.960 --> 0:04:39.080 out what it is, or have they. It's been an 0:04:39.080 --> 0:04:42.679 open puzzle for decades now in physics what is dark matter? 0:04:42.760 --> 0:04:45.200 What is it made out of? And everybody knows that 0:04:45.200 --> 0:04:47.800 the people who figure that out will go down in 0:04:48.000 --> 0:04:52.080 history as having answered one of the biggest questions in physics. 0:04:52.520 --> 0:04:55.240 And so it's definitely a big fat prize out there 0:04:55.279 --> 0:04:57.960 waiting for somebody to win. Yeah, and in fact, there 0:04:58.080 --> 0:05:00.880 is somebody out there who believe eves they've seen it 0:05:01.160 --> 0:05:03.800 and maybe even know what it is, and in fact 0:05:03.800 --> 0:05:07.479 they've been certain about this for about twenty years. That's right. 0:05:07.600 --> 0:05:09.400 Of all the folks out there looking for dark matter, 0:05:09.520 --> 0:05:12.400 there's a group in Italy that are very confident in 0:05:12.440 --> 0:05:15.839 their signal they've seen something that they think can only 0:05:15.880 --> 0:05:19.400 be explained by dark matter. Well, Italians being confident about 0:05:19.400 --> 0:05:23.600 something Danna that feels like pretty on brand. Yeah, So 0:05:23.880 --> 0:05:27.159 the big question is why doesn't anybody believe this experiment 0:05:27.240 --> 0:05:29.960 and the results they found. So today on the podcast 0:05:29.960 --> 0:05:37.880 will be tackling the question why doesn't anybody believe the 0:05:38.000 --> 0:05:41.800 DAMA experiment. Now, Daniel, this is DAMA, d A m 0:05:41.920 --> 0:05:45.719 A not Dharma experiment. Like in the TV series Lost, 0:05:45.960 --> 0:05:49.440 I feel like maybe there's a conspiracy here, Maybe the 0:05:49.440 --> 0:05:52.240 to are connected. Maybe Lost was actually about dark matter 0:05:52.400 --> 0:05:56.760 the whole time. Maybe yeah, yes, the monster watch me 0:05:56.839 --> 0:05:58.839 to ad have like this dark cloud, it could have 0:05:58.839 --> 0:06:00.679 been dark matter, It could have been in dark matter. 0:06:00.800 --> 0:06:03.360 They were physicists the whole time, and we finally put 0:06:03.360 --> 0:06:05.840 it together right here on the podcast and unlocked the 0:06:05.880 --> 0:06:10.360 mister Jack never had a chance. That's right now. It's 0:06:10.400 --> 0:06:14.359 the DAMA experiment, and it's had several iterations. It's called Dama, 0:06:14.360 --> 0:06:17.320 it's called Dama slash libra, but they're all fundamentally the 0:06:17.360 --> 0:06:21.279 same experiment in the same location, seeing the same amazing 0:06:21.400 --> 0:06:25.080 signal that looks like dark matter. But nobody seems to 0:06:25.120 --> 0:06:27.800 believe that. The consensus in the particle physics community is 0:06:27.839 --> 0:06:31.520 that DAMA has not discovered dark matter, and other experiments 0:06:31.560 --> 0:06:34.240 continue to hunt for dark matter in lots of different ways. 0:06:34.680 --> 0:06:37.960 So it's a fascinating question when one group sees something 0:06:37.960 --> 0:06:40.680 but nobody else believes it. What do you do? Wow? 0:06:41.279 --> 0:06:43.960 What does DAMA stand for? The d A comes from 0:06:44.080 --> 0:06:46.720 dark and the m a comes from matter, so da 0:06:46.839 --> 0:06:49.919 mash is just short for dark matter. You know, people 0:06:49.920 --> 0:06:52.440 can't be bothered to say the whole name dark matter, 0:06:52.480 --> 0:06:56.280 so they just squished it together into DAMA. Okay, they've 0:06:56.320 --> 0:06:59.960 just appropriated the first two letters for the acronym. That's right, 0:07:00.160 --> 0:07:02.559 and the follow up experiment will appropriate the other letters. 0:07:02.600 --> 0:07:07.839 It will be alright. So these folks in Italy twenty 0:07:07.920 --> 0:07:11.600 years ago claim they have found a signal for dark matter, 0:07:12.400 --> 0:07:14.800 and they've been pretty confident about it, but nobody in 0:07:14.800 --> 0:07:17.320 the field believed them. And I was wondering whether people 0:07:17.400 --> 0:07:20.239 outside the field have followed this, if it's trickled through 0:07:20.280 --> 0:07:23.920 into mainstream media, if people are aware of this incredible, 0:07:24.040 --> 0:07:27.520 unexplained signal and a dark matter experiment, because usual Daniel 0:07:27.520 --> 0:07:29.360 went out there into the wilds of the Internet to 0:07:29.400 --> 0:07:34.840 ask people, why does nobody believe the DAMA experiment discovered 0:07:35.040 --> 0:07:37.160 dark matter? So thank you to those of you who 0:07:37.160 --> 0:07:40.520 are willing to speculate on a physics question without googling. 0:07:40.840 --> 0:07:44.280 If you'd like to participate, and here your uninformed speculation 0:07:44.360 --> 0:07:47.400 on the podcast, Please write to us two questions at 0:07:47.520 --> 0:07:50.400 Daniel and Jorge dot com. Here's what people had to say. 0:07:50.640 --> 0:07:53.320 I'm not sure I've never heard of this experiment before. 0:07:53.480 --> 0:07:57.680 Then there are so many experiments right now and I'm 0:07:57.680 --> 0:08:02.200 not sure I heard about this one. I don't know. 0:08:04.040 --> 0:08:07.960 Um is it? Has there been no further evidence of 0:08:08.160 --> 0:08:11.240 dark matter that's been found? Have they not been able 0:08:11.240 --> 0:08:13.840 to replicate it? I imagine it's something like that, or 0:08:13.840 --> 0:08:15.840 maybe they like look back at the results and we're like, no, 0:08:16.000 --> 0:08:19.560 this could just be interference. Um, I don't I don't know. 0:08:20.000 --> 0:08:22.800 I would assume that the discovery of dark matter would 0:08:22.840 --> 0:08:25.800 be on par with the photo the first photo of 0:08:25.840 --> 0:08:28.800 the black hole ever taken, and that was from Page News. 0:08:29.080 --> 0:08:33.480 And because I haven't heard anything about dark matter being discovered, 0:08:34.000 --> 0:08:37.760 that maybe they didn't discover it, there was noise in 0:08:37.800 --> 0:08:40.679 the data, or they're still taking their time to calculate 0:08:40.679 --> 0:08:43.800 the results. If the Deema experiment did discover a dark matter, 0:08:44.679 --> 0:08:48.400 you think that we have more information about what it is, 0:08:48.720 --> 0:08:52.120 all right? Not a lot of brand recognition for Doma. No, 0:08:52.760 --> 0:08:54.320 I don't know. That means they should have chosen a 0:08:54.320 --> 0:08:57.120 better name, or they just need a better pr team. 0:08:57.160 --> 0:09:00.400 But because nobody in physics has really accepted their result, 0:09:00.440 --> 0:09:03.240 it doesn't seem to have trickled out to the wider community. 0:09:03.400 --> 0:09:05.120 I like this answer that somebody said, there are so 0:09:05.120 --> 0:09:07.560 many experiments right now, I'm not sure I've heard about 0:09:07.600 --> 0:09:10.240 this one, Like, do you feel like maybe you saturated 0:09:10.240 --> 0:09:13.960 the market with acronym experiments. Oh, there are a lot 0:09:14.160 --> 0:09:17.200 of dark matter experiments, you know, and they have crazy names. 0:09:17.400 --> 0:09:21.160 There's Zenon, there's lux those LZ, this co signed, this cogent, 0:09:21.240 --> 0:09:24.600 there's Zeppelin, this coupe, there's dark Side. These are just like, 0:09:24.640 --> 0:09:26.760 you know, half of the dark matter experiments out there. 0:09:26.840 --> 0:09:29.720 It's an enormous race. It's like a land grab. You know. 0:09:29.800 --> 0:09:33.120 Everybody's rushing to figure out what dark matter is, knowing 0:09:33.160 --> 0:09:35.240 that one of these groups might figure it out and 0:09:35.600 --> 0:09:38.200 not only win a Noel Prize, but you know, answer 0:09:38.240 --> 0:09:41.440 a deep question about the universe. So it's very tempting. 0:09:41.480 --> 0:09:44.240 It's a very hot area of research. Yeah, and it's 0:09:44.280 --> 0:09:47.439 a big part of the universe. It's twenty seven that's right. 0:09:47.480 --> 0:09:50.199 If you add up all the energy in like a 0:09:50.320 --> 0:09:54.720 random cube of space, then twenty seven percent of that 0:09:54.880 --> 0:09:58.600 energy is devoted to making dark matter, whereas only five 0:09:58.720 --> 0:10:00.839 percent of that energy is a the stuff you and 0:10:00.880 --> 0:10:03.520 I are made out of, and stars and dust and 0:10:03.559 --> 0:10:05.760 gas and most of the stuff that we think about 0:10:05.840 --> 0:10:08.840 in the universe. It's just a tiny little fraction. So 0:10:08.920 --> 0:10:13.080 discovering dark matter doesn't just like answer some abstract physics question. 0:10:13.160 --> 0:10:15.360 It tells us what the universe is, because it's much 0:10:15.400 --> 0:10:18.439 more than just what we're made at. Yeah, all right, 0:10:18.480 --> 0:10:21.559 So these folks have discovered dark matter, or claim to 0:10:21.600 --> 0:10:24.480 have discovered it, but nobody believes them. Daniel, Is that 0:10:24.600 --> 0:10:26.960 like a night mer scenario for you as a scientist, 0:10:27.080 --> 0:10:29.880 Like to discover something amazing and then have everybody think 0:10:29.880 --> 0:10:32.200 that you're crazy. It's one of several nightmares, you know. 0:10:32.280 --> 0:10:35.840 Other varieties of those nightmares are like you see something amazing, 0:10:36.000 --> 0:10:38.440 you published something, it makes a big splash, and then 0:10:38.520 --> 0:10:41.280 you realize that it was wrong. That's the kind of 0:10:41.280 --> 0:10:43.560 thing that happened to the Opera experiment that claimed that 0:10:43.640 --> 0:10:46.400 neutrinos were going faster than light, and then it turns 0:10:46.400 --> 0:10:49.320 out they had miscalibrated because one of their cables wasn't 0:10:49.440 --> 0:10:52.120 jiggled in the right way. They were Italian too, weren't 0:10:52.160 --> 0:10:56.840 they They were also Italian, although you know that could 0:10:56.920 --> 0:11:00.360 just be coincidence on not casting expersions on the Italian 0:11:00.360 --> 0:11:04.240 physics community. Lots of wonderful Italian collaborators on the outlets 0:11:04.280 --> 0:11:07.160 experiment with me. But yeah, that's one nightmare, and the 0:11:07.200 --> 0:11:09.719 other one is that nobody reproduces your result, and so 0:11:09.880 --> 0:11:12.720 nobody believes your result and you're left there with data 0:11:12.760 --> 0:11:15.240 that you believe that you just can't convince your colleagues, 0:11:15.480 --> 0:11:19.560 because remember, science is a human endeavor. It's by people 0:11:19.640 --> 0:11:21.599 and four people, and in the end you have to 0:11:21.640 --> 0:11:24.480 convince the community that what you've done holds up, that 0:11:24.520 --> 0:11:27.480 you've uncracked something real about the universe and not just 0:11:27.520 --> 0:11:30.720 an artifact of how you've done your experience. Yeah, I 0:11:30.720 --> 0:11:33.319 feel like that's that's a similar nightmare for cartoonist. It's 0:11:33.320 --> 0:11:35.840 like you write the perfect joke and nobody gets it. 0:11:37.320 --> 0:11:39.319 Would I still be satisfied? Like, I think maybe I 0:11:39.320 --> 0:11:41.840 would still be satisfied. I'd be like, yes, I wrote 0:11:41.880 --> 0:11:45.040 the best joke, but everyone else is a fool. Well, 0:11:45.080 --> 0:11:47.080 that's a good question for you as a cartoonist. Is 0:11:47.080 --> 0:11:50.240 there any correlation between how popular our cartoon is and 0:11:50.240 --> 0:11:54.679 how much you like. Alright, So Dama claims they saw 0:11:54.800 --> 0:11:57.560 dark matter and measured it. So Daniel step us through it. 0:11:57.640 --> 0:12:00.680 What exactly did they see? So what are doing is 0:12:00.720 --> 0:12:04.400 they're looking for a tiny little particles of dark matter. 0:12:04.720 --> 0:12:07.720 Now we don't know that dark matter is a particle, 0:12:08.000 --> 0:12:10.000 but it's just sort of the best idea we have 0:12:10.280 --> 0:12:12.240 is that matter is made of particles, and so we 0:12:12.280 --> 0:12:15.480 figure maybe dark matter is also made out of dark 0:12:15.559 --> 0:12:19.560 matter particles, some new kind of particle we haven't seen before. 0:12:19.920 --> 0:12:21.880 Now we think that dark matter is made out of 0:12:21.960 --> 0:12:25.480 matter because we see that it affects the rotation of galaxies. 0:12:25.840 --> 0:12:28.880 Galaxies are spinning really really fast, and without dark matter 0:12:29.080 --> 0:12:32.640 they would tear themselves apart and throw stars into interstellar space. 0:12:33.040 --> 0:12:35.520 So we think dark matter is real. It's made of matter. 0:12:36.040 --> 0:12:37.880 We're pretty sure that it's not made of any kind 0:12:37.880 --> 0:12:40.320 of matter we're familiar with. It's not made out of 0:12:40.400 --> 0:12:43.280 quarks or leptons, because if so, we would have seen 0:12:43.320 --> 0:12:45.240 it already and it would have affected the way the 0:12:45.360 --> 0:12:48.280 universe formed in very early moments. So we think that 0:12:48.400 --> 0:12:51.320 dark matter has stuff to it. We think it's probably 0:12:51.360 --> 0:12:54.800 made of particles. We think it's a new kind of particle. 0:12:55.280 --> 0:12:57.000 But the thing that makes it hard to find is 0:12:57.040 --> 0:12:59.520 that it doesn't really interact in the ways that we're 0:12:59.559 --> 0:13:02.720 familiar with. Yeah, because everything that has matter that we 0:13:02.760 --> 0:13:05.360 know about is a particle, right, Like, can you think 0:13:05.400 --> 0:13:08.040 of a way in which something could have matter but 0:13:08.240 --> 0:13:11.839 not like a particle or a particle field. Actually, there 0:13:11.840 --> 0:13:16.160 are a set of really fascinating ideas about unparticle matter, 0:13:16.600 --> 0:13:19.520 matter that's made us something that's smooth and continuous. We're 0:13:19.559 --> 0:13:21.400 going to dig into that in a podcast in a 0:13:21.400 --> 0:13:24.280 few weeks, which is really fascinating. But it's hard to 0:13:24.280 --> 0:13:27.200 think about. It's harder to think about than particle matter. 0:13:27.720 --> 0:13:30.040 And when you don't know what you're doing in physics, 0:13:30.080 --> 0:13:32.120 what you do is you start with the familiar, and 0:13:32.200 --> 0:13:34.680 until you've ruled that out as a possibility, you don't 0:13:34.679 --> 0:13:37.960 really take steps into the weirder, crazier options. And so 0:13:38.000 --> 0:13:40.320 we start with the simplest idea that, since everything we 0:13:40.360 --> 0:13:42.920 know is made of particles, maybe dark matter is also 0:13:43.080 --> 0:13:45.880 made of particles, but we don't actually know that. It's 0:13:45.880 --> 0:13:48.040 like you have to check off the obvious first. Yeah, 0:13:48.200 --> 0:13:51.080 you start with the simplest explanation. It's easiest, you know 0:13:51.160 --> 0:13:53.480 how to do it. It makes the most sense, and 0:13:53.559 --> 0:13:55.440 so you start there, you know. But we have a 0:13:55.520 --> 0:13:58.280 variety of folks working in a variety of different ideas, 0:13:58.280 --> 0:14:00.480 but this is sort of the main us. That's the 0:14:00.480 --> 0:14:04.040 first time I hear that phrase on particle matter. What 0:14:04.160 --> 0:14:06.880 did you just call it? Like smooth matter or creamy matter? 0:14:07.520 --> 0:14:09.520 Creamy matter sounds like something I would like to put 0:14:09.559 --> 0:14:12.840 on top of my pasta about dark creamy matter even better? 0:14:13.800 --> 0:14:15.840 Oh yeah, that sounds like something my wife would study. 0:14:16.520 --> 0:14:18.679 But the thing that we don't know about dark matter 0:14:19.120 --> 0:14:22.520 is how to see it. Because dark matter doesn't give 0:14:22.560 --> 0:14:26.640 off light, it doesn't reflect light. It's basically totally transparent 0:14:26.800 --> 0:14:28.520 to matter. You might think of dark matter and think 0:14:28.520 --> 0:14:31.360 of something black or dark that you couldn't see through, 0:14:31.680 --> 0:14:34.880 but it's the opposite. It's something invisible. Life passes right 0:14:34.920 --> 0:14:37.840 through it without interacting, except of course, that dark matter 0:14:37.880 --> 0:14:40.720 has gravity, and so it can bend space and slightly 0:14:40.760 --> 0:14:43.240 distort the path of light. Right, So dark matter doesn't 0:14:43.240 --> 0:14:46.880 interact with us. Our devices are stuff in the usual 0:14:46.920 --> 0:14:50.520 ways through electromagnetic forces. But people think that it may 0:14:50.560 --> 0:14:53.720 interact with us through other forces like the weak force. Yeah, 0:14:53.920 --> 0:14:57.120 we hope that dark matter has some way of interacting 0:14:57.160 --> 0:14:59.680 with our kind of matter, not just because we want 0:14:59.680 --> 0:15:02.200 to feel connected to dark matter, but because all of 0:15:02.200 --> 0:15:05.120 our experiments are made of our kind of matter, and 0:15:05.160 --> 0:15:07.240 so if we're gonna try to catch some dark matter, 0:15:07.520 --> 0:15:09.760 that we have to build our experiments out of something 0:15:10.080 --> 0:15:13.680 that matter will interact with. You Imagine like dark matter 0:15:13.760 --> 0:15:15.760 is flying through the room and you're trying to catch one, 0:15:16.120 --> 0:15:18.880 but you're using a catcher's mit that dark matter flies 0:15:19.000 --> 0:15:21.560 right through. Now you have no chance to catch a 0:15:21.600 --> 0:15:25.160 particle of dark matter. So we hope that dark matter 0:15:25.280 --> 0:15:28.280 does have some kind of interaction with our kind of matter. 0:15:28.360 --> 0:15:31.160 We don't know exactly what kind of interaction that would be. 0:15:31.400 --> 0:15:34.680 We're pretty sure it's not electromagnetic. We know it doesn't 0:15:34.760 --> 0:15:37.960 use the strong force. We're almost certain it doesn't use 0:15:38.000 --> 0:15:40.520 the weak nuclear force. So we're hoping there might be 0:15:40.600 --> 0:15:44.080 a new force, an undiscovered force, that connects dark matter 0:15:44.200 --> 0:15:46.640 with our kind of matter. It's like trying to catch 0:15:46.640 --> 0:15:50.120 a ghost exactly. It's trying to catch a tiny, tiny 0:15:50.120 --> 0:15:53.160 little ghost with a super tiny little catcher's mit. Alright, 0:15:53.200 --> 0:15:55.880 so then how did this DAMA experiment work? What are 0:15:55.920 --> 0:15:59.560 they using to claim to have caught dark matter. So 0:15:59.560 --> 0:16:02.320 there's a whole category of experiments looking for dark matter 0:16:02.360 --> 0:16:05.080 that are called direct detection. And what they do is 0:16:05.080 --> 0:16:08.280 they set up a big lump of material, usually very 0:16:08.360 --> 0:16:11.920 quiet material that doesn't interact very much with things normally, 0:16:12.280 --> 0:16:14.520 and they let it sit there underground under a bunch 0:16:14.560 --> 0:16:17.080 of shielding, and they hope that a piece of dark 0:16:17.120 --> 0:16:20.320 matter will fly through the Earth and bounce into a 0:16:20.440 --> 0:16:24.160 molecule in their lump of stuff. And when that happens, 0:16:24.160 --> 0:16:26.240 they'll get a little flash of light or in some 0:16:26.280 --> 0:16:29.400 cases a wiggle of an electron. And so they've built, 0:16:29.440 --> 0:16:31.840 you know, essentially a big catcher's mitt and they hope 0:16:31.880 --> 0:16:34.480 that a piece of dark matter will bump into it 0:16:34.640 --> 0:16:36.920 and give them a little signal. So that's the whole 0:16:37.000 --> 0:16:40.520 category of these kinds of experiments. And people use different 0:16:40.600 --> 0:16:43.920 kinds of material. Some use liquid zen on, some people 0:16:44.000 --> 0:16:48.480 use super cool semiconductors. This experiment is using crystals, crystals 0:16:48.480 --> 0:16:51.920 of sodium iodide, and so you put them on in 0:16:52.040 --> 0:16:53.880 like a box and your hope is that the dark 0:16:53.880 --> 0:16:57.040 matter goes through the box. But then somehow, you know, 0:16:57.080 --> 0:17:00.560 it causes your crystalline sodium to spark somehow, Yeah, you're 0:17:00.600 --> 0:17:03.800 hoping that dark matter can interact with the protons or 0:17:03.840 --> 0:17:07.879 the neutrons inside the atoms of these crystals, and then occasionally, 0:17:08.080 --> 0:17:10.560 one out of a trillion times, or ten trillion times, 0:17:10.600 --> 0:17:13.200 or a hundred trillion times, it will bump into one 0:17:13.200 --> 0:17:15.719 of those protons and give it a little boost. And 0:17:15.760 --> 0:17:19.199 the reason they choose this sodium idied crystal is that 0:17:19.240 --> 0:17:21.920 it has a special property. When it does get bumped, 0:17:22.160 --> 0:17:25.159 it tends to resettle back into its old situation, and 0:17:25.160 --> 0:17:27.720 it does so by giving off a little photon. So 0:17:27.760 --> 0:17:30.800 as you say it sparks, and physics we call that scintillation, 0:17:31.119 --> 0:17:33.440 So sends off a little photon and then you can 0:17:33.480 --> 0:17:36.720 catch that with these photo multiplier tubes. So you're basically 0:17:36.720 --> 0:17:40.000 looking at a dark crystal underground hoping to see a 0:17:40.040 --> 0:17:44.760 flash of mine, sorry, scintillating. Daniel and so Doma claimed 0:17:44.760 --> 0:17:47.240 that they've seen dark matter, that they have a signal 0:17:47.280 --> 0:17:50.080 for dark matter, but nobody seems to believe them. So 0:17:50.200 --> 0:17:53.880 let's dig into what they actually saw and why it's 0:17:53.880 --> 0:17:57.080 so hard to accept. But first let's take a quick 0:17:57.080 --> 0:18:12.000 break a right, Daniel, we're talking about the Dama experiment 0:18:12.000 --> 0:18:14.600 in Italy who have been claiming for twenty years that 0:18:14.640 --> 0:18:17.960 they found dark matter, but nobody believes them. And so 0:18:18.520 --> 0:18:22.040 they they have a big vat of crystalline sodium underground, 0:18:22.160 --> 0:18:25.720 shielded and they've seen it maybe interact with dark matter. 0:18:25.880 --> 0:18:28.199 So what exactly have they seen? Yeah, so what they 0:18:28.240 --> 0:18:31.840 see is really striking because what they're looking for are 0:18:31.880 --> 0:18:34.760 these little flashes of light. But of course dark matter 0:18:34.800 --> 0:18:37.000 is not the only thing that might give you those 0:18:37.040 --> 0:18:40.560 flashes of light. You could have like radioactive decay in 0:18:40.600 --> 0:18:43.760 the rock. This thing is underground in the Grand Sasso 0:18:43.880 --> 0:18:47.080 mind in Italy, and you know, the rocks nearby can 0:18:47.160 --> 0:18:50.280 have a little bit of radioactive decay or muans can 0:18:50.320 --> 0:18:52.560 penetrate the rock is sometimes and get all the way 0:18:52.600 --> 0:18:54.760 down to your experiment. So you have some sources of 0:18:54.800 --> 0:18:57.400 background that are not dark mattered. Isn't it shielded? Don't 0:18:57.440 --> 0:19:00.119 they put it behind big thick walls or something? And 0:19:00.160 --> 0:19:01.879 first of all, they have buried it in this mind 0:19:01.960 --> 0:19:05.160 under like you know, miles of marble and granite, which 0:19:05.200 --> 0:19:08.080 is awesome shielding. But then yes, absolutely they have the 0:19:08.080 --> 0:19:11.320 things surrounded by concrete and they have fiberglass. They do 0:19:11.400 --> 0:19:13.600 their best to shield it, but you can't always shield 0:19:13.600 --> 0:19:17.240 things completely perfectly, there will always be some level of background. 0:19:17.680 --> 0:19:19.840 So what they do is they look for something that 0:19:20.000 --> 0:19:22.600 only the dark matter could do, a signal that would 0:19:22.600 --> 0:19:24.919 look different if it was dark matter or if it 0:19:25.000 --> 0:19:28.320 was one of these normal everyday backgrounds. And the idea 0:19:28.359 --> 0:19:32.080 they had is to look for seasonal variations, like in 0:19:32.080 --> 0:19:34.800 in the fall, it tastes a little bit like pumpking spice, 0:19:34.960 --> 0:19:38.920 and then in the winter it tastes. In the spring 0:19:38.960 --> 0:19:41.000 it smells a little bit like flowers. No, they have 0:19:41.119 --> 0:19:43.719 this idea of taking advantage of the fact that the 0:19:43.800 --> 0:19:47.480 Earth is moving through the dark matter at different speeds, 0:19:47.960 --> 0:19:50.560 and when we moved through the dark matter at higher speed, 0:19:50.760 --> 0:19:54.080 they should see more dark matter interacting with their detector, 0:19:54.359 --> 0:19:56.639 and when we moved through it at lower speed, they 0:19:56.680 --> 0:20:00.080 should see less dark matter interacting with their detector. And 0:20:00.119 --> 0:20:02.680 that's just because we're going around the Sun, and so 0:20:02.720 --> 0:20:05.560 sometimes we're moving more with the dark matter and sometimes 0:20:05.560 --> 0:20:09.760 we're moving more against the dark matter. It's kind of 0:20:09.800 --> 0:20:12.560 like this old idea of the ether, kind of, isn't it. 0:20:12.640 --> 0:20:13.960 You know? If we are in a big cloud of 0:20:14.040 --> 0:20:16.919 dark matter and the Sun and the Earth is moving 0:20:17.119 --> 0:20:20.199 through it as we go around the Sun. Then you know, 0:20:20.320 --> 0:20:22.680 sometimes we'll see it going one way and then other 0:20:22.720 --> 0:20:25.840 times we'll be seeing the dark matter fly by another way. Yeah, 0:20:25.880 --> 0:20:27.840 it's very similar to the idea of the ether and 0:20:27.880 --> 0:20:30.080 that there's sort of a rest frame. All right. We 0:20:30.119 --> 0:20:33.040 don't know exactly where the dark matter is, but we 0:20:33.119 --> 0:20:36.600 imagine it's pretty smoothly distributed through the galaxy. Again, we 0:20:36.640 --> 0:20:39.040 don't know that it might have clumped, but dark matter 0:20:39.119 --> 0:20:41.760 is very slow moving, and so we think it's pretty diffuse. 0:20:42.240 --> 0:20:44.640 We think it's pretty much spread out. We also don't 0:20:44.680 --> 0:20:47.600 know how fast it's rotating. We think it's rotating around 0:20:47.640 --> 0:20:49.919 the center of the galaxy, just like our kind of 0:20:49.960 --> 0:20:53.320 matter is. But regardless of how fast it's rotating, you 0:20:53.320 --> 0:20:56.840 can imagine some rest frame for the dark matter. And 0:20:56.880 --> 0:20:59.320 then the Earth is moving in that rest frame because 0:20:59.320 --> 0:21:02.240 it orbits the Sun, and so some part of the 0:21:02.320 --> 0:21:04.840 year it's moving through it faster than other parts of 0:21:04.840 --> 0:21:08.000 the year. So their idea is, well, let's look for that. 0:21:08.359 --> 0:21:11.119 If this is dark matter or not muans are crazy, 0:21:11.240 --> 0:21:14.080 radioactive decay or something else, then we should see a 0:21:14.160 --> 0:21:17.760 seasonal variation in our signal. We should see more interactions 0:21:17.800 --> 0:21:21.879 in June than in December, because we're assuming that dark 0:21:21.920 --> 0:21:25.920 matter kind of has a velocity, and sometimes we're going 0:21:25.960 --> 0:21:28.760 against the current of dark matter and sometimes we're going 0:21:28.800 --> 0:21:31.000 with the current. Yeah, well, you don't have to assume 0:21:31.000 --> 0:21:34.120 that dark matter has a velocity with respect to the galaxy. 0:21:34.160 --> 0:21:37.640 It's our velocity relative to the dark matter that's important. 0:21:37.760 --> 0:21:39.439 So you can always just pick your rest frame. And 0:21:39.440 --> 0:21:41.320 if you pick your rest frame as the dark matter, 0:21:41.800 --> 0:21:44.679 then our velocity through that dark matter has to be 0:21:44.760 --> 0:21:47.760 changing year to year because we're orbiting the Sun and 0:21:47.880 --> 0:21:50.439 dark matter is not orbiting our Sun, right. But I 0:21:50.480 --> 0:21:52.320 think you have to also account for the fact that 0:21:52.320 --> 0:21:56.040 we're going around the galaxy, right, because if we were 0:21:56.040 --> 0:21:59.520 just going around the Sun then and dark matter was static, 0:21:59.680 --> 0:22:03.080 we would seed go the same speed by us. It 0:22:03.080 --> 0:22:05.120 would just be in different directions. It's it's more about 0:22:05.119 --> 0:22:09.960 the interactions with with our rotation around the galaxy to right. Yeah, 0:22:10.040 --> 0:22:11.680 you can think about it that way, you know, think 0:22:11.720 --> 0:22:14.040 about it like the Earth and the Sun are moving 0:22:14.040 --> 0:22:17.920 in the same direction relative to the dark matter or 0:22:17.960 --> 0:22:20.280 relative to the rest of the galaxy during part of 0:22:20.320 --> 0:22:22.720 the year, and in the other part of the year 0:22:22.760 --> 0:22:25.200 that you're moving the opposite direction. So the Sun is 0:22:25.240 --> 0:22:27.360 moving around the galaxy in one direction and the Earth 0:22:27.440 --> 0:22:30.120 is going the other way, because it's a different part 0:22:30.119 --> 0:22:33.240 of its cycle around the Sun. And so these velocities 0:22:33.280 --> 0:22:35.199 add up differently. Sometimes they add up to make a 0:22:35.320 --> 0:22:38.240 larger velocity relative to the dark matter, and sometimes they 0:22:38.240 --> 0:22:40.600 point in the opposite direction of each other, and so 0:22:40.640 --> 0:22:43.720 they make a smaller velocity relative to the dark matter. 0:22:44.359 --> 0:22:46.400 So like if you're just standing on Earth, you would 0:22:46.480 --> 0:22:50.200 sort of see dark matter sometimes flow past year really 0:22:50.280 --> 0:22:54.320 quickly and sometimes more slowly, like a dark matter wind. Yes, 0:22:54.400 --> 0:22:57.199 just like a dark matter wind. And so that's the 0:22:57.280 --> 0:22:59.520 idea is like let's look to see if there are 0:22:59.600 --> 0:23:03.680 more dark matter interactions in June then in December, because 0:23:03.680 --> 0:23:06.760 that seasonal variation would be what you expect to see 0:23:06.920 --> 0:23:11.440 from dark matter, which has this seasonally varying velocity relative 0:23:11.480 --> 0:23:13.199 to the Earth. And it has nothing to do with 0:23:13.240 --> 0:23:16.399 pumpking spice or maybe we're shorts in the summer. Tip. Well, 0:23:16.400 --> 0:23:19.280 you know, nobody understands the results of this experiment, and 0:23:19.320 --> 0:23:22.720 so maybe it is just the cumulative effect of pumpkin spice, 0:23:22.760 --> 0:23:26.800 lot pumping spice espressos because you know there in Italy, 0:23:27.160 --> 0:23:29.480 all right, So they've seen a signal. Basically, what is 0:23:29.520 --> 0:23:32.480 what you're saying is that they've seen a seasonal variation 0:23:32.920 --> 0:23:35.960 in their detection of dark matter according to sort of 0:23:35.960 --> 0:23:39.000 the motion of the Earth. So which might be like, hey, 0:23:39.080 --> 0:23:42.600 maybe dark matter is there and it is seasonal. Yes, exactly, 0:23:42.640 --> 0:23:45.800 they are seeing this seasonal variation. If you look at 0:23:45.800 --> 0:23:47.679 a plot of their results, the sort of number of 0:23:47.720 --> 0:23:50.000 sparks they see is a function of the day. Then 0:23:50.040 --> 0:23:52.280 you see it goes up and it peaks in June, 0:23:52.359 --> 0:23:55.280 and it falls down and it minimizes in December, and 0:23:55.320 --> 0:23:57.600 then it goes back up again. And you know, they've 0:23:57.600 --> 0:24:00.680 been running this experiment for years, which allows them to 0:24:00.720 --> 0:24:02.840 see lots of these cycles. And so it's not just 0:24:02.920 --> 0:24:06.000 like one little wiggle which could have been anything. It's 0:24:06.040 --> 0:24:08.960 definitely a cycle, and it's definitely annual, and it definitely 0:24:09.040 --> 0:24:12.000 peaks and dips in the right places. Wow. Yeah, they've 0:24:12.000 --> 0:24:14.960 been seeing signals for fourteen years. Like it's not a 0:24:15.040 --> 0:24:18.000 one time fluke that they see the pattern. It's like 0:24:18.000 --> 0:24:20.320 they've they've been measuring this and it goes up and 0:24:20.359 --> 0:24:24.000 down yearly for fourteen years. Yeah, for at least fourteen years. 0:24:24.040 --> 0:24:26.919 They've had a few iterations of this experiment. They've upgraded this, 0:24:27.000 --> 0:24:29.960 they've tweaked that, and so different plots have different numbers 0:24:29.960 --> 0:24:32.640 of years on them. But you know, almost twenty years 0:24:32.640 --> 0:24:34.760 ago they started seeing this signal. In the first few 0:24:34.800 --> 0:24:37.320 years people were like, nah, keep taking data, we don't 0:24:37.320 --> 0:24:39.520 believe it. But now they have these plots of just 0:24:39.600 --> 0:24:42.360 like wiggle and wiggle and wiggle and wiggle, and it's 0:24:42.520 --> 0:24:45.000 very unlikely that it's a fluke. You know, if you 0:24:45.080 --> 0:24:47.760 do the calculation, what are the chances of seeing this 0:24:47.920 --> 0:24:51.000 kind of wiggle from something which is actually flat, it's 0:24:51.119 --> 0:24:54.760 very very small. The threshold for discovering particle physics is 0:24:54.880 --> 0:24:58.320 five sigma, which means like, you know, one in millions 0:24:58.320 --> 0:25:01.239 of chances of being a background in fluctuation. But they 0:25:01.280 --> 0:25:04.800 have nine sigma, which is like almost unimaginable. So this 0:25:04.880 --> 0:25:08.719 is definitely a signal something is happening here. The remaining 0:25:08.800 --> 0:25:12.560 question is is it really dark matter? All right? So 0:25:12.600 --> 0:25:15.880 they have fourteen years of data, it's a pretty clear 0:25:16.240 --> 0:25:19.359 wiggle that there's dark matter, but nobody believes them. So 0:25:19.560 --> 0:25:22.320 what's going on, Daniel? Do people just don't believe their data? 0:25:22.760 --> 0:25:25.239 Are they suspicious? And is it that nobody has been 0:25:25.280 --> 0:25:27.880 able to see it in the same way. What's going on, Well, 0:25:27.960 --> 0:25:29.800 there's a lot of things going on here. Some of 0:25:29.800 --> 0:25:32.320 them are technical and scientific, and some of them are 0:25:32.320 --> 0:25:36.639 sort of sociological and maybe personal. Some people don't like pasta. 0:25:37.080 --> 0:25:40.639 Everybody likes pasta. Some people just don't put parmesan on 0:25:40.680 --> 0:25:43.440 their shrimp pasta, which is you know, unimaginable. That's a 0:25:43.560 --> 0:25:47.000 no no, that's a yes yes for me anyway. One 0:25:47.080 --> 0:25:50.040 problem is that they have not really shared the details 0:25:50.160 --> 0:25:52.840 of their data. Like they show up at conferences, they 0:25:52.840 --> 0:25:56.000 write papers, they show these results that look great, but 0:25:56.080 --> 0:25:58.639 they haven't opened up their box to show us, like 0:25:58.680 --> 0:26:01.639 the nuts and bolts how they analyze the data and 0:26:01.680 --> 0:26:04.280 shared a lot of details. And as you can expect, 0:26:04.320 --> 0:26:07.240 physicists want to see details. You can't just show up 0:26:07.280 --> 0:26:10.320 with your one discovery plot and say, look, we discovered it, 0:26:10.400 --> 0:26:12.840 let's all move on. People want to dig into it 0:26:12.880 --> 0:26:15.280 and understand it and think about how to double check it. 0:26:15.640 --> 0:26:18.880 And they've been pretty closed with their data, right. Well, 0:26:18.920 --> 0:26:20.760 it used to be that people who are super closed, 0:26:20.760 --> 0:26:23.119 but I think the more recent trend is for everyone 0:26:23.160 --> 0:26:25.440 to just open up their you know, files and let 0:26:25.480 --> 0:26:28.360 everyone sift through your numbers. Yeah, and you know, extraordinary 0:26:28.400 --> 0:26:31.840 claims require extraordinary evidence, and so you have to like 0:26:31.960 --> 0:26:35.800 respond to questions and give details when people ask you 0:26:35.840 --> 0:26:37.760 send a paper in for a review, for example, the 0:26:37.800 --> 0:26:40.720 reviewers can to ask for more experiments or additional plots, 0:26:40.720 --> 0:26:42.560 because what they want to do is make sure this 0:26:42.640 --> 0:26:45.119 is real, that it makes sense to them. Can't just 0:26:45.200 --> 0:26:48.280 be one pretty plot has to reflect something true about 0:26:48.280 --> 0:26:51.640 the universe, and so people want to consistent story, something 0:26:51.680 --> 0:26:53.679 that tells them this is really dark matter and not 0:26:53.880 --> 0:26:57.080 something else. So what's their case for not releasing the data? 0:26:57.280 --> 0:27:00.560 Are they under audit or something? I don't know. It's 0:27:00.560 --> 0:27:02.600 a bit of a cultural thing, you know. They show 0:27:02.720 --> 0:27:06.159 up at conferences, and as one dark matter theorists described 0:27:06.200 --> 0:27:09.960 to me, they seem aggressively uninterested in what other people 0:27:10.000 --> 0:27:12.480 think about their data. I think you're saying they're too cool. 0:27:12.640 --> 0:27:15.199 They believe their results, they're very confident in it, but 0:27:15.280 --> 0:27:18.440 they haven't shared enough details for other people to really 0:27:18.440 --> 0:27:21.760 gain confidence in their results. And so instead people have 0:27:21.800 --> 0:27:24.880 had to turn to other experiments, which should be sensitive 0:27:24.920 --> 0:27:27.560 to the same signal, to see if they can confirm right. 0:27:27.640 --> 0:27:30.679 Because maybe another experiment that with a similar setup, like 0:27:30.720 --> 0:27:33.920 with a vat of stuff waiting to interact with dark matter, 0:27:34.040 --> 0:27:37.240 would also see like these seasonal spikes. Yeah, you would 0:27:37.240 --> 0:27:39.800 expect so. And in fact, one of the other big 0:27:39.920 --> 0:27:42.560 dark matter experiments in the world, the zeno On experiment, 0:27:42.880 --> 0:27:45.800 is sitting in the same labs. Like they have this 0:27:45.880 --> 0:27:48.600 big holid out space under this mountain to do these 0:27:48.680 --> 0:27:51.000 kinds of experiments, and they gave part of it to 0:27:51.119 --> 0:27:53.840 the Doma experiment and part of it to the Xenon experiment. 0:27:54.040 --> 0:27:56.720 So the Xenon experiment is literally in the same place 0:27:56.760 --> 0:27:59.560 as the Doma experiment. So if there's any issues with 0:27:59.640 --> 0:28:03.960 like seasonal variations on temperature or something else, right, that's 0:28:03.960 --> 0:28:06.679 the concerns that there might be some seasonal source of 0:28:06.760 --> 0:28:10.280 background that they haven't accounted for. Zenon is in the 0:28:10.359 --> 0:28:13.000 same place, it's in the same lab. They do not 0:28:13.240 --> 0:28:17.639 see this seasonal variation they see, So nobody's seen this 0:28:17.720 --> 0:28:22.080 seasonal variation. There's several of these dark matter experiments, but 0:28:22.160 --> 0:28:24.840 nobody has seen this kind of variation with the year. 0:28:25.000 --> 0:28:27.760 That's right, there's a huge variety of dark matter experiments. 0:28:27.800 --> 0:28:31.520 They have different like active materials like liquid zenn versus 0:28:31.520 --> 0:28:34.440 sodium idide crystals. They're in different places around the world, 0:28:34.520 --> 0:28:38.040 they have different sensor technologies. Nobody has seen the results 0:28:38.080 --> 0:28:41.280 that's consistent with what DAMA has seen, and so you 0:28:41.360 --> 0:28:43.880 might ask, like, well, would they have seen these results? 0:28:44.040 --> 0:28:46.840 Is it possible for dark matter to only interact with 0:28:46.880 --> 0:28:49.640 this one kind of material and not the others? And 0:28:49.680 --> 0:28:53.000 so people have built like boutique theories of dark matters 0:28:53.000 --> 0:28:55.800 to try to explain this Dama experiment. Why DAMA would 0:28:55.800 --> 0:28:59.200 see it but Xenon wouldn't. Maybe it only interacts with 0:28:59.240 --> 0:29:02.120 neutrons and set of protons or prefers protons in one 0:29:02.200 --> 0:29:05.200 arrangement to another kind of arrangement, But nobody has been 0:29:05.240 --> 0:29:08.200 able to explain it. And in the meantime, people have 0:29:08.320 --> 0:29:11.440 built copies of the Dama experiment that are essentially the 0:29:11.520 --> 0:29:15.560 same technology, the same active material, the same kind of sensors, 0:29:15.720 --> 0:29:18.400 but just in different locations to try to double check 0:29:18.520 --> 0:29:22.360 DAMA really interesting. They've used like this crystalline sodium also, 0:29:22.720 --> 0:29:25.480 and they've put it inside of a mine and and 0:29:25.600 --> 0:29:28.480 do they see anything. They don't see anything yet. So 0:29:28.520 --> 0:29:31.880 there's an experiment in South Korea called Cosigne, and I 0:29:31.960 --> 0:29:34.760 have no idea what that stands for But they basically 0:29:34.800 --> 0:29:38.240 have duplicated the DOMAS experiments set up, but they don't 0:29:38.240 --> 0:29:41.200 see the results. Now, this is a difficult thing to do. 0:29:41.360 --> 0:29:43.840 It takes years of data to say are we seeing 0:29:43.880 --> 0:29:46.640 a flat line or are we seeing wiggles. So so 0:29:46.720 --> 0:29:48.600 far they only have a couple of years of data 0:29:48.880 --> 0:29:52.000 and they say their results are in quote severe tension 0:29:52.240 --> 0:29:55.400 with the DAMA results, but they also admit that it 0:29:55.480 --> 0:29:57.960 could be consistent with DAMA. They just don't have enough 0:29:58.040 --> 0:30:01.880 data yet. So time will tell if Cosign sees a 0:30:01.920 --> 0:30:05.080 wiggle or not. But so far the indications are that 0:30:05.160 --> 0:30:07.520 they haven't interesting. They want to see it happen before 0:30:07.520 --> 0:30:11.760 they co sign the certification. There, that's right, they want 0:30:11.800 --> 0:30:14.480 to see their own cosign in the data. Let's see 0:30:14.480 --> 0:30:18.160 their own wiggles. H alright. But still DOMA is pretty 0:30:18.160 --> 0:30:21.240 confident about their result. DOMA is pretty confident in their results. 0:30:21.320 --> 0:30:24.040 You know, they believe that it's dark matter. People have 0:30:24.160 --> 0:30:26.640 thought about all sorts of other sources of background, like 0:30:27.160 --> 0:30:30.200 maybe the rock heats up in the summer and it 0:30:30.280 --> 0:30:33.680 gives off more radiation and that leaks into the experiment, 0:30:33.960 --> 0:30:35.640 And they have all sorts of ways to monitor this 0:30:35.760 --> 0:30:38.000 and they don't see that kind of thing. So physicists 0:30:38.000 --> 0:30:40.320 in the community has been a lot of energy brainstorming 0:30:40.480 --> 0:30:44.680 possible explanations for what might explain is other than dark matter, 0:30:44.960 --> 0:30:48.200 more prosaic explanations, and so far they haven't figured out 0:30:48.240 --> 0:30:51.360 anything that they can point to that says, here's why 0:30:51.520 --> 0:30:54.320 DOMA is seeing this signal. It's not dark matter, it's 0:30:54.720 --> 0:30:57.160 you know, growth of plants on the top of the 0:30:57.200 --> 0:30:59.880 mountain is releasing something in June or something like that. 0:31:00.320 --> 0:31:02.840 But nobody's found that explanation yet. All right, let's get 0:31:02.880 --> 0:31:06.800 into what maybe DAMA is seeing in their signals of 0:31:06.960 --> 0:31:10.720 dark matter and why nobody believes any of these. But 0:31:10.840 --> 0:31:22.560 first let's take a quick break. All right, Daniel d 0:31:22.640 --> 0:31:25.320 DAMA experiment has been seeing a dark matter signal for 0:31:25.480 --> 0:31:29.280 fourteen years, but nobody believes them and nobody can replicate 0:31:29.360 --> 0:31:32.240 the results. So what are some of the possibilities heres 0:31:32.480 --> 0:31:34.480 of what they could be seeing. Do they have like 0:31:34.880 --> 0:31:37.840 a wire that's not connected right but only once a year, 0:31:38.920 --> 0:31:41.240 or is it could be the air conditioning in the 0:31:41.360 --> 0:31:43.640 room that you know, in the summer it kicks up more, 0:31:43.800 --> 0:31:45.760 or what could it be? So the sort of two 0:31:45.960 --> 0:31:50.800 categories of possible explanations. One are non dark matter explanations right, 0:31:51.200 --> 0:31:55.080 and ideas there are like they use nitrogen in their experiment, 0:31:55.240 --> 0:31:57.480 but it also has a little bit of argon in it. 0:31:57.720 --> 0:32:00.800 They surround the experiment with argon, and it could be 0:32:01.360 --> 0:32:04.920 that some of that are gone has seasonal variations in it, 0:32:05.280 --> 0:32:08.640 that is more activated during June than in December, based 0:32:08.720 --> 0:32:11.360 on based on what how how would the argon know 0:32:11.600 --> 0:32:14.560 what the season was? Well, it's not that an individual 0:32:14.880 --> 0:32:18.840 argon adom knows the season or like celebrates Christmas. It's 0:32:18.880 --> 0:32:22.400 that the amount of radio active aregon around the experiment 0:32:22.520 --> 0:32:25.920 depends on the season. The contaminant we're interested in here 0:32:26.040 --> 0:32:29.560 is are gone thirty seven, which is made when neutrons 0:32:29.680 --> 0:32:32.160 hit calcium in the soil or are gone thirty six 0:32:32.280 --> 0:32:35.400 in the atmosphere, and the neutron flux, the number of 0:32:35.480 --> 0:32:38.640 neutrons coming in to make are gone thirty seven has 0:32:38.720 --> 0:32:42.719 a seasonal variation due to the variation and atmosphere density, 0:32:42.760 --> 0:32:44.640 which it determines like how many it make it all 0:32:44.680 --> 0:32:47.120 the way down. But you know, people are really scratching 0:32:47.120 --> 0:32:50.240 their heads trying to think of crazy explanations, because of course, 0:32:50.480 --> 0:32:53.320 the folks and Dama are solid physicists, and they've taken 0:32:53.360 --> 0:32:55.600 care of all the obvious effects that have as much 0:32:55.680 --> 0:32:58.120 you know, climate controlling as they can manage in this 0:32:58.280 --> 0:33:00.600 environment to try to isolate themselves from any sort of 0:33:00.640 --> 0:33:04.120 seasonal variations. But you know, at the colliders were also 0:33:04.240 --> 0:33:07.440 sensitive to really really tiny effects. The phases of the 0:33:07.600 --> 0:33:11.240 moon affect the shape of the rock near Lake Geneva, 0:33:11.600 --> 0:33:14.840 and that affects the bending of the accelerator because it's 0:33:14.920 --> 0:33:18.240 under the rock, and people notice these things. What you 0:33:18.320 --> 0:33:22.120 see title effects in your data. Absolutely, the train schedules 0:33:22.480 --> 0:33:25.959 in Geneva affected the results of colliders in those tunnels, 0:33:26.000 --> 0:33:28.960 and so we can be very sensitive to very small effects. 0:33:29.280 --> 0:33:31.880 What how did how did the trains affect your the 0:33:31.960 --> 0:33:35.080 particle closure? Is it like the vibrations of the trains 0:33:35.280 --> 0:33:38.040 or just more people on campus at certain times. It's 0:33:38.080 --> 0:33:41.640 really amazing. Actually it was the electricity from the trains. 0:33:42.080 --> 0:33:44.640 Some of the extra current leaks down and made little 0:33:44.760 --> 0:33:48.680 gentle magnetic fields which actually influenced the operation of the collider. 0:33:49.320 --> 0:33:53.160 And so when you're hunting down tiny little explanations and 0:33:53.240 --> 0:33:56.040 you're trying to separate the ideas from like dark matter 0:33:56.240 --> 0:33:59.640 to other basic prosaic explanations. You've got to go all 0:33:59.720 --> 0:34:02.440 the way down the list for really small effects. All right, 0:34:02.480 --> 0:34:04.800 So what else could this signal they're seeing? What else 0:34:04.840 --> 0:34:07.520 could it be? Could it be, you know, some other 0:34:07.680 --> 0:34:10.319 kind of theory about how dark matter interact. It could 0:34:10.360 --> 0:34:12.680 certainly be, like there could be other ways that dark 0:34:12.719 --> 0:34:14.960 matter interacts. It could be that dark matter is something 0:34:15.080 --> 0:34:18.040 weird that we hadn't imagined before, and that's why we're 0:34:18.040 --> 0:34:20.839 seeing it only in these crystals but not in others. Now, 0:34:20.920 --> 0:34:23.360 the cosine experiments and the other ones that are replicating 0:34:23.440 --> 0:34:26.239 this make it pretty hard to follow that kind of 0:34:26.320 --> 0:34:29.440 explanation because they're basically a copy of DAMA and they 0:34:29.560 --> 0:34:32.600 don't see it. But put those aside, and let's say 0:34:32.920 --> 0:34:35.160 maybe cosine and the other experiments that are trying to 0:34:35.200 --> 0:34:38.080 replicate it just don't have enough data yet. People have 0:34:38.239 --> 0:34:40.879 cooked up theories that try to explain why dark matter 0:34:40.960 --> 0:34:44.080 interacts with sodium iodide more than it interacts with zenon, 0:34:44.239 --> 0:34:48.200 for example, like dark maybe dark matter pre first Italians 0:34:48.560 --> 0:34:50.920 or you know, less of vacation in Italy more than 0:34:51.000 --> 0:34:52.920 it does in South Korea. Yeah, and it also has 0:34:52.960 --> 0:34:55.920 to do with the mass because xenon is heavier, for example, 0:34:56.160 --> 0:34:58.960 than other elements, and so dark matter is very very 0:34:59.080 --> 0:35:01.320 low mass. If it doesn't have a lot of oomph 0:35:01.400 --> 0:35:03.520 to it, then it might be that it's just harder 0:35:03.600 --> 0:35:05.960 for it to push zen on than to interact with 0:35:06.320 --> 0:35:08.879 sodium iodide. And so people have come up with these 0:35:08.920 --> 0:35:12.240 theories of like very light dark matter, but those theories 0:35:12.239 --> 0:35:15.239 are also hard to explain because DAMA builds a new 0:35:15.400 --> 0:35:18.480 system in their experiment, one that should be sensitive to 0:35:18.560 --> 0:35:21.839 sort of lower energy results, and they don't see any 0:35:21.960 --> 0:35:24.879 difference in the low energy results and the original ones. 0:35:25.480 --> 0:35:28.040 And if there was very very light dark matter, they 0:35:28.040 --> 0:35:31.000 would expect to see a larger signal in these low 0:35:31.160 --> 0:35:34.600 energy recoils, but they don't. So people have been a 0:35:34.680 --> 0:35:37.439 lot of time trying to construct these fancy dark matter 0:35:37.560 --> 0:35:41.000 theories that could explain DAMA as dark matter, but none 0:35:41.040 --> 0:35:43.800 of them really hold water. So the consensus in the 0:35:43.880 --> 0:35:47.040 dark matter community is that DAMA is not seeing dark matter. 0:35:47.080 --> 0:35:49.360 They're seeing something else. We just don't know what it 0:35:49.520 --> 0:35:51.200 is yet. I guess the problem too, is that, you know, 0:35:51.239 --> 0:35:53.360 as we go around the sun, it's not just about 0:35:53.920 --> 0:35:56.480 more sunlight or less sunlight. It's also kind of there's 0:35:56.480 --> 0:35:59.600 other stuff going out there in space, right, absolutely, there 0:35:59.640 --> 0:36:02.480 are very variations and like how many Muans strike the 0:36:02.560 --> 0:36:05.959 Earth because Muans come to the Earth from cosmic rays 0:36:06.000 --> 0:36:09.080 and not just from the Sun, but also from galactic sources, 0:36:09.440 --> 0:36:11.600 like there are mus being created by other stars from 0:36:11.640 --> 0:36:14.320 from the galactic center that hit the Earth, and so 0:36:14.560 --> 0:36:18.520 that varies also with the seasons for similar reasons. And 0:36:18.719 --> 0:36:20.879 so it could be that they're seeing some weird dawk 0:36:20.880 --> 0:36:24.279 Off effect from these cosmic Muan seasons. It could be 0:36:24.360 --> 0:36:27.840 that nobody's really nailed that down yet, all right, So 0:36:27.920 --> 0:36:31.400 the consensus is that they're not seeing dark matter, but 0:36:31.480 --> 0:36:33.600 how they told DAMA that they that everyone thinks so, 0:36:33.800 --> 0:36:37.960 or is it's just sort of a like a background whispering, 0:36:38.080 --> 0:36:40.280 Like I don't think they've seen it. DAMA is definitely 0:36:40.360 --> 0:36:44.160 aware that their explanation is not accepted, but they are 0:36:44.320 --> 0:36:48.239 very confident, you know, they are sure that their experiment 0:36:48.400 --> 0:36:51.200 indicates the presence of dark matter particles in the halo. 0:36:51.640 --> 0:36:54.319 There's a quote from the long time leader the experiment saying, 0:36:54.600 --> 0:36:58.719 there is no alternative explanation for our signal. So they're 0:36:58.800 --> 0:37:03.360 very confident. They are aware that nobody believes them, but 0:37:03.600 --> 0:37:06.960 they're powering forward. You know, what do you think, Daniel, 0:37:07.120 --> 0:37:11.680 Are you aggressively interested or aggressively uninterested in this result? 0:37:12.880 --> 0:37:15.120 When I've heard about it, I was super excited. I 0:37:15.200 --> 0:37:18.080 was like, what a beautiful signal, what a nice experiment. 0:37:18.480 --> 0:37:21.000 I would love to believe it. But you know, before 0:37:21.040 --> 0:37:23.160 you believe something like this, you really have to see 0:37:23.200 --> 0:37:26.320 it replicated. Because we're not interested in one cute story 0:37:26.360 --> 0:37:29.080 of an experiment that sees a cool wiggle. We're interested 0:37:29.120 --> 0:37:32.480 in the actual story of dark matter. And if it's 0:37:32.480 --> 0:37:34.839 a real story of science, you should appear in more 0:37:34.920 --> 0:37:36.800 than one place. You should be able to see it 0:37:36.960 --> 0:37:39.399 using more than one technique, or you should at least 0:37:39.440 --> 0:37:41.839 be able to tell coherent story about why it's here 0:37:41.920 --> 0:37:44.560 and not there. Because the universe we think is a 0:37:44.640 --> 0:37:47.120 coherent story is that we should be able to pull 0:37:47.160 --> 0:37:49.320 it apart by looking at it from different angles. And 0:37:49.440 --> 0:37:52.400 this is so difficult to see that you really have 0:37:52.640 --> 0:37:54.400 to see it in more than one place before you 0:37:54.480 --> 0:37:56.879 believe it. Right. You don't want it to be weak 0:37:56.960 --> 0:38:00.880 pasta right, that's right. And so there's an other experiment 0:38:01.000 --> 0:38:04.640 being built in the southern hemisphere, in the Saber experiment, 0:38:04.920 --> 0:38:07.640 and it's very similar to the Dama experiment, except again 0:38:07.680 --> 0:38:10.800 it's in the southern hemisphere, and so it should have 0:38:11.080 --> 0:38:16.719 the opposite seasonal related systematic uncertainties because it's cold when 0:38:16.840 --> 0:38:19.560 Dama is warm, and it'll be warm when Dama is cold. 0:38:19.800 --> 0:38:22.440 If it's not related to the dark matter, but if 0:38:22.480 --> 0:38:25.880 it is, it should see the same seasonal changes, right, 0:38:25.880 --> 0:38:27.960 because it's moving along. It's it's about the movement of 0:38:28.000 --> 0:38:30.799 the Earth exactly, and so it's just another cross check, 0:38:30.920 --> 0:38:34.840 like let's move all temperature related things off by six months. 0:38:35.120 --> 0:38:37.920 The dark matter shouldn't change at all. So if they 0:38:37.960 --> 0:38:41.560 see a signal and it's shifted, that suggests that it's 0:38:41.760 --> 0:38:44.960 temperature seasonal variation thing. If they see a signal and 0:38:45.040 --> 0:38:47.759 it's not shifted, then that removes a lot of the 0:38:47.800 --> 0:38:51.560 possible explanations for temperature variations. It doesn't change things like 0:38:51.680 --> 0:38:54.560 you know, cosmic muon seasons, but it helps us sort 0:38:54.600 --> 0:38:57.040 of isolate what this might be, right, and did they 0:38:57.080 --> 0:38:59.640 find anything. They're still building it and so we don't 0:38:59.680 --> 0:39:02.680 know the results of the Saber experiment. It's being built 0:39:02.760 --> 0:39:06.080 in a gold mine in Australia, and everybody is very 0:39:06.160 --> 0:39:09.040 eager to see what that experiment has to say, all right, 0:39:09.120 --> 0:39:12.319 So I guess the answer is stay tuned. I guess 0:39:12.400 --> 0:39:16.040 nobody believes the DAMA experiment because it hasn't been replicated, 0:39:16.200 --> 0:39:18.600 and it could still be other things that cause it 0:39:18.800 --> 0:39:22.200 the signal. That's right, there's no coherent explanation in which 0:39:22.320 --> 0:39:25.520 DAMA is seeing dark matter and somehow nobody else is 0:39:25.600 --> 0:39:28.320 able to see it, and so the most likely explanation 0:39:28.440 --> 0:39:30.719 is that it's some weird source of signal that they 0:39:30.800 --> 0:39:33.520 haven't isolated yet. But it could still be. It could 0:39:33.560 --> 0:39:36.480 be that there are pockets of dark matter where the 0:39:36.560 --> 0:39:38.719 dark matter is interacting with some weird kind of matter 0:39:38.800 --> 0:39:41.680 that only exists around the DAMA experiment in Italy for 0:39:41.800 --> 0:39:44.320 some weird reason. But you have to have sort of 0:39:44.520 --> 0:39:47.720 crazier and crazier thoughts to explain this and to explain 0:39:47.840 --> 0:39:50.120 the lack of signal and all the other experience. I 0:39:50.680 --> 0:39:52.720 guess it's it's sort of the charge for both sides 0:39:52.960 --> 0:39:56.000 of people trying to prove this data, right, Like, it's 0:39:56.480 --> 0:39:58.759 it's getting harder to come up with excuses, but it's 0:39:58.760 --> 0:40:02.080 also getting harder to applicated. Yeah. Absolutely, but it's also 0:40:02.160 --> 0:40:04.719 a fun puzzle if you're an experimentalist, and you'd like 0:40:04.840 --> 0:40:07.080 to dig around in the data and understand where is 0:40:07.120 --> 0:40:08.840 this coming from? Why is it look this way and 0:40:08.920 --> 0:40:11.080 not the other way. It's not a deep mystery of 0:40:11.120 --> 0:40:13.239 the universe, but it is a fun question to ask, 0:40:13.360 --> 0:40:15.440 like what could be the source of this. It's a 0:40:15.680 --> 0:40:19.000 nice little detective mystery, and the person who actually figures 0:40:19.040 --> 0:40:21.560 it out eventually might not win the Nobel Prize, but 0:40:21.680 --> 0:40:26.160 they will scratch longstanding itch in particle physics, a dark 0:40:27.760 --> 0:40:30.120 a dark itch that really matters. All Right, We'll stay 0:40:30.200 --> 0:40:32.680 tuned and maybe in the next couple of years we'll 0:40:32.760 --> 0:40:36.000 hear news about whether it's a real or not, whether 0:40:36.080 --> 0:40:40.320 they deserve the Nobel Prize, or just a nice dinner 0:40:41.040 --> 0:40:43.800 with a nice glass of Italian one and plenty of 0:40:43.880 --> 0:40:46.680 parmesan sprinkled on top. All right, thanks for joining us, 0:40:47.280 --> 0:40:57.440 see you next time. Thanks for listening, and remember that 0:40:57.600 --> 0:41:00.360 Daniel and Jorge explained The universe is a shin of 0:41:00.480 --> 0:41:03.800 I Heart Radio or more podcast from my Heart Radio. 0:41:03.960 --> 0:41:07.480 Visit the I Heart Radio, Apple Apple Podcasts, or wherever 0:41:07.640 --> 0:41:09.280 you listen to your favorite shows.