Daniel and Kelly’s Extraordinary Universe - A discounted dark matter discovery

Episode Date: October 22, 2020

Why do particle physicists discount the beautiful signal of dark matter from the DAMA experiment? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

This is an I-Heart podcast. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, everything changed. There's been a bombing at the TWA terminal. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of Law and Order Criminal Justice System

On the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Why are TSA rules so confusing? You got a hood of you on take it all! I'm Manny. I'm Noah. This is Devin. And we're best friends and journalists with a new podcast called No Such Thing, where we get to the bottom of questions like that.

Why are you screaming at me? I can't expect what to do. Now, if the rule was the same, Same. Go off on me. I deserve it. You know, lock him up. Listen to No Such Thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. No such thing. I'm Dr. Joy Hardin Bradford, host of the Therapy for Black Girls podcast.

I know how overwhelming it can feel if flying makes you anxious. In session 418 of the Therapy for Black Girls podcast, Dr. Angela Nielbornet and I discuss flight anxiety. What is not a norm is to a lot. allow it to prevent you from doing the things that you want to do, the things that you were meant to do. Listen to therapy for black girls on the IHeartRadio app, Apple Podcasts, or wherever you get your podcast. Hey, Daniel, as a particle physicist, what's the one thing you would most like to discover?

Ooh, if I could pick just one thing to discover? Yeah, like, go wild. your biggest scientific ambition? Well, that's a great question, but it's not actually that hard to pick. I would want to discover dark matter. Because it's such a big mystery? Yeah, it's one of the biggest open questions in modern science, and I personally really want to know the answer.

All right, but here's a catch. What have you discovered what it is, but nobody believes you? Are you still interested? Oh, man, like a modern-day physics, Cassandra. That sounds a little bit like torture, but, you know, as long as I know the answer to the questions about the universe, I would still want to find out. So it's all about you, huh?

Science is personal. Hi, I'm Horan, a cartoonist and the creator of PhD comics. Hi, I'm Daniel. I'm a particle physicist, and I'm desperately seeking dark matter. How desperate are you, Daniel? Not desperate enough to make up my data, but desperate enough to consider almost anything. Are you desperate enough to move to Italy, maybe, to do your research? I do like that black pasta they have over there, so I call that dark matter, then yeah. I think it's called squid ink pasta.

Well, they've discovered something delicious at the very least. But welcome to our podcast, Daniel and Jorge Explain the Universe, a production of IHeartRadio. In which we take a bite out of the tastiest intellectual questions of the universe. We chew, we swallow, we explain all of it to you. So we serve it up on a dish and hope that you slurp it all up. So you can think about the universe and everything in it. Because everything about the universe is wondrous and amazing and it makes us curious. But it doesn't just make scientists curious.

We think it makes everybody curious. That curiosity is wonderful and we want to cherish it and satisfy it by explaining to you some of the mysteries of the universe. And there are still a lot of mysteries out there. There are big chunks of the universe. We don't know anything about, and there are big questions about the very nature of our cosmos and where we came from and also what is even in it. That's right. Recently, scientists have cracked open the universe and discovered that there's a lot of stuff out there that we don't know, that we don't understand. There are new kinds of stuff out there, and it makes us desperately curious.

What is it? Why is it? Why is there so much more of it than our kind of stuff? So many questions, so few answers. And is it delicious also? It's a big question in everybody's mine. How much of it should you have on top of your pasta? And can you put cheese on it? Are there rules for what you can't put Parmesan cheese on?

Absolutely. You can put Parmesan cheese on everything. That's the rule. Even seafood pasta? I feel like that's an unstated rule. That's a whole other podcast episode. We can't get into that today, man. We have to stay on topic.

Seafood matter. Seafood matters. But anyways, a big bite of the universe that we don't know anything about is a big mystery called dark matter. 27% of all of the energy and matter in the universe is something called dark matter, but we don't know what it is. And we would love to understand it.

We would love to break it apart and figure out is it made out of some tiny little particle we've never seen before? Is it lots of different particles? Is it something else which isn't even a particle? So physicists all over the world are using lots of different techniques to try to isolate dark matter

and figure out what kind of particle it is. Yeah, because it's swimming all around us, right? Like, it's everywhere. In fact, probably when you eat pasta, you are taking big bite fools of dark matter at the same time. That's right. But fortunately, your body doesn't digest it, so you don't gain all of that mass. But yes, dark matter, we think, is all around us. It's part of the universe, but it's not spread evenly through the universe. It's clumped together, just like our matter. So we think that our galaxy is swimming in a massive halo of dark matter and that the earth is flying through a wind of dark matter.

And so physicists are using lots of techniques to try to discover this, looking at it colliding with itself in the center of the galaxy. We're trying to make it in underground collisions at the Large Hadron Collider. And also we're trying to detect this dark matter wind. Yeah, everybody seems to be looking for it, but it's really hard because you can't touch it or see it. And so far, nobody has really gotten a chance to figure out what it is or have they. It's been an open puzzle for decades now in physics. What is dark matter?

What is it made out of? And everybody knows that the people who figure that out will go down in history as having answered one of the biggest questions in physics. And so it's definitely a big fat prize out there waiting for somebody to win. Yeah. And in fact, there is somebody out there who believes they've seen it and maybe even know what it is. And in fact, they've been starting about this for about 20 years. That's right. Of all the folks out there looking for dark matter, there's a group in Italy that are very confident in their city.

They've seen something that they think can only be explained by dark matter. Well, Italian is being confident about something, Daniel, that feels like pretty on brand. Yeah, so the big question is, why doesn't anybody believe this experiment and the results they found? So today on the podcast, we'll be tackling the question. Why doesn't anybody believe the Dama experiment? Now, Daniel, this is D-A-M-A-N-A, not D-A-A-A-A-A. Dharma experiment, like in the TV series Lost. I feel like maybe there's a conspiracy here.

Maybe the two are connected. Maybe Lost was actually about dark matter the whole time. Maybe, yeah. Yes, the monster was made out of like this dark cloud. It could have been dark matter. It could have been dark matter. They were physicists the whole time. And we finally put it together right here on the podcast and unlock the mystery.

Jack never had a chance. That's right. No, it's the Dharma experiment. and it's had several iterations. It's called DOMA. It's called DOMA slash Libra. But they're all fundamentally the same experiment in the same location, seeing the same amazing signal that looks like dark matter.

But nobody seems to believe it. The consensus in the particle physics community is that DOMA has not discovered dark matter and other experiments continue to hunt for dark matter in lots of different ways. So it's a fascinating question. When one group sees something but nobody else believes it, what do you do? Wow. What does Dama stand for? The D-A comes from dark and the M-A comes from matter. So Dama is just short for dark matter.

You know, people can't be bothered to say the whole name, dark matter. So they just squished it together into Dama. Oh, okay. They've just appropriated the first two letters for the acronym. That's right. And the follow-up experiment will appropriate the other letters. It'll be Kirtr. All right.

So these folks in Italy, 20 years ago, claim they have found, a signal for dark matter and they've been pretty confident about it, but nobody in the field believes them. And I was wondering whether people outside the field have followed this, if it's trickled through into mainstream media, if people are aware of this incredible, unexplained signal in a dark matter experiment. So as usual, Daniel went out there into the wilds of the internet to ask people, why does nobody believe the Dama experiment discovered dark matter? So thank you to those of you who are willing to speculate on a physics question without Googling if you'd like to participate and hear your uninformed speculation on the podcast please

write to us to questions at danielanhorpe.com here's what people had to say i'm not sure i've never heard of this experiment before man there are so many experiments right now and i'm not sure i heard about this one i don't know um is it has there been no further evidence of dark matter that's been found? Have they not been able to replicate it? I imagine it's something like that, or maybe they looked back of the results and were like, no, this could just be interference. I don't, I don't know. I would assume that the discovery of dark matter would be on par with the photo, the first photo of the black hole ever taken. And that was front page news. And because I haven't heard anything about dark matter being discovered, that maybe they didn't discover it.

There was noise in the data or they're still taking their time to calculate the results. If the DEMA experiment did discover a dark matter, you would think that we'd have more information about what it is. All right. Not a lot of brand recognition for Adama. No. I don't know. That means they should have chosen a better name or they just need a better PR team. But because nobody in physics has really accepted their result, it doesn't seem to have trickled out to the wider community. I like this answer to that somebody said there are so many experiments right now. not sure. I've heard about this one. Like, do you feel like maybe you saturated the market with acronym experiments? Oh, there are a lot of dark matter experiments, you know, and they have

crazy names. There's xenon. There's Lux. There's LZ. This cosine. This cogent. There's Zepplin, this coop. There's dark side. These are just like, you know, half of the dark matter experiments out there. It's an enormous race. It's like a land grab. You know, everybody's rushing to figure out what dark matter is, knowing that one of these groups might figure it out. And not only win a well prize, but, you know, answer a deep question about the universe. So it's very tempting. It's a very hot area of research. Yeah. And it's a big part of the universe. It's 27%. That's right. If you add up all the energy in like a random cube of space, then 27% of that energy is devoted to making dark matter, whereas only 5% of that energy is the kind of stuff you and I are made out of. In

stars and dust and gas. And most of the stuff that we think about in the universe, It's just a tiny little fraction. So discovering dark matter doesn't just, like, answer some abstract physics question. It tells us what the universe is because it's much more than just what we're made out of. Yeah. All right. So these folks have discovered dark matter or claimed to have discovered it, but nobody believes them. Daniel, is that like a nightmare scenario for you as a scientist, like to discover something amazing

and then have everybody think that you're crazy? It's one of several nightmares. You know, other varieties of those nightmares are like, you see something amazing. you publish something, it makes a big splash, and then you realize it was wrong. That's the kind of thing that happened to the opera experiment that claimed that neutrinos were going faster than light, and then it turns out they had miscalibrated

because one of their cables wasn't jiggled in the right way. Oh, they were Italian too, weren't they? They were also Italian, although, you know, that could just be coincidence. I'm not casting aspersions on the Italian physics community. Lots of wonderful Italian collaborators on the Atlas experiment with me. But yeah, that's one nightmare. And the other one is that nobody reproduces your result.

And so nobody believes your result. And you're left there with data that you believe that you just can't convince your colleagues. Because remember, science is a human endeavor. It's by people and for people. And in the end, you have to convince the community that what you've done holds up, that you've uncracked something real about the universe and not just an artifact of how you've done your experiment. Wow. Yeah.

I feel like that's a similar nightmare for cartoonas. It's like you write the perfect joke. And nobody gets it. Like, hmm, would I still be satisfied? I think maybe I would still be satisfied. I'd be like, yes, I wrote the best joke, but everyone else is a fool. Well, that's a good question for you as a cartoonist. Is there any correlation between how popular a cartoon is and how much you like it?

All right. So, Dama claims they saw dark matter and measured it. So Daniel, step us through it. What exactly did they see? So what they're doing is they're looking for tiny little particles of dark matter. Now, we don't know that dark matter is a particle, but it's just sort of the best idea we have is that matter is made of particles. And so we figure maybe dark matter is also made out of dark matter particles, some new kind of particle we haven't seen before. Now, we think that dark matter is made

out of matter because we see that it affects the rotation of galaxies. Galaxies are spinning really, really fast. And without dark matter, they would tear themselves apart and throw stars into interstellar space. So we think dark matter is real. It's made of matter. We're pretty sure that it's not made of any kind of matter we're familiar with. It's not made it of quarks or leptons. Because if so, we would have seen it already and it would have affected the way the universe formed in the very early moments. So we think that dark matter has stuff to it. We think it's probably made of particles. We think it's a new kind of particle. But the thing that makes it hard to find is that it doesn't really interact in the ways that we're familiar with.

Yeah, because everything that has matter that we know about is a particle, right? Like, can you think of a way in which something could have matter, but not like a particle or a particle field? Yeah, actually, there are a set of really fascinating ideas about unparticle matter, matter that's made of something that's smooth and continuous. We're going to dig into that in a podcast in a few weeks, which is really fascinating. But it's hard to think about. It's harder to think about than particle matter.

And when you don't know what you're doing in physics, what you do is you start with the familiar. And until you've ruled that out as a possibility, you don't really take steps into the weirder, crazier options. And so we start with the simplest idea that since everything we know is made of particles, maybe dark matter is also made of particles. But we don't actually know that. It's like you have to check off the obvious first. Yeah. You start with the simplest explanation. It's easiest.

You know how to do it. It makes the most sense. And so you start there. You know, but we have a variety of folks working on a variety. of different ideas, but this is sort of the main thrust. That's the first time I hear that phrase, unparticle matter. Why don't you just call it like smooth matter or creamy matter? Creamy matter sounds like something I would like to put on top of my pasta.

How about dark creamy matter? Even better. Oh, yeah, that sounds like something my wife would study. But the thing that we don't know about dark matter is how to see it, because dark matter doesn't give off light, it doesn't reflect light. It's basically totally transparent to matter. You might think of dark matter and think of something black or dark that you couldn't see through. But it's the opposite.

It's something invisible. Life passes right through it without interacting, except, of course, that dark matter has gravity, and so it can bend space and slightly distort the path of light. Right. So dark matter doesn't interact with us, our devices, our stuff, in the usual ways through electromagnetic forces. But people think that it may interact with us through other forces, like the weak force. Yeah. We hope that dark matter has some way of interacting with.

our kind of matter, not just because we want to feel connected to dark matter, but because all of our experiments are made of our kind of matter. And so if we're going to try to catch some dark matter, then we have to build our experiments out of something that matter will interact with. You know, imagine like dark matter is flying through the room and you're trying to catch one, but you're using a catcher's mitt that dark matter flies right through. Now you have no chance to catch a particle of dark matter. So we hope that dark matter does have some kind of interaction with our kind of matter. We don't know exactly what kind of interaction that would be.

We're pretty sure it's not electromagnetic. We know it doesn't use the strong force. We're almost certain it doesn't use the weak nuclear force. So we're hoping there might be a new force, an undiscovered force that connects dark matter with our kind of matter. Wow. It's like trying to catch a ghost. Exactly.

It's trying to catch a tiny, tiny little ghost with a super tiny little catcher smit. All right. So then how did this Dama experiment work? What are they using to claim to have caught dark matter? So there's a whole category of experiments looking for dark matter that are called direct detection. And what they do is they set up a big lump of material, usually very quiet material that doesn't interact very much with things normally. And they let it sit there underground under a bunch of shielding. And they hope that a piece of dark matter will fly through the earth and bounce into a molecule in their lump of stuff.

And when that happens, they'll get a little flash of light or in some cases a wiggle of an electron. And so they've built, you know, essentially a big catrismid and they hope that a piece of dark matter will bump into it and give them a little signal. So that's the whole category of these kinds of experiments. And people use different kinds of material. Some use liquid xenon. Some people use super cool semiconductors. This experiment is using crystals, crystals of sodium iodide. And so you put them on in like a box.

And your hope is that the dark matter goes through the box, but then somehow, you know, causes your crystalline sodium to spark somehow. Yeah, you're hoping that dark matter can interact with the protons or the neutrons inside the atoms of these crystals and that occasionally one out of a trillion times or 10 trillion times or 100 trillion times, it will bump into one of those protons and give it a little boost. And the reason they choose this sodium iodide crystal is that it has a special property. When it does get bumped, it tends to resettle back into its old situation, and it does so by giving off a little photon. So as you say, it sparks.

In physics, we call that scintillation. So it sends off a little photon, and then you can catch that with these photomultiplier tubes. So you're basically looking at a dark crystal underground, hoping to see a flash of light. It's very scintillating, Daniel. And so Dama claimed that they've seen dark matter, that they have a signal for dark matter, but nobody seems to believe them. So let's dig into what they actually saw and why it's so hard to accept. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport.

The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently the explosion actually impelled metal glass. The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and order, criminal justice system is back.

In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast. So we'll find out soon. This person writes, My boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her.

Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor, and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him?

Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his person? professor or not. To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I'm Dr. Scott Barry Kaufman, host of the psychology podcast. Here's a clip from an upcoming conversation about exploring human potential. I was going to schools to try to teach kids these skills, and I get eye rolling from teachers or I get students who would be like, it's easier to punch someone in the face. When you think about emotion regulation, like you're not going to choose an adapted to

strategy which is more effortful to use unless you think there's a good outcome as a result of it if it's going to be beneficial to you because it's easy to say like go you go blank yourself right it's easy it's easy to just drink the extra beer it's easy to ignore to suppress seeing a colleague who's bothering you and just like walk the other way avoidance is easier ignoring is easier denial is easier drinking is easier yelling screaming is easy complex problem solving meditating, you know, takes effort. Listen to the psychology podcast on the IHartRadio app, Apple Podcasts, or wherever you get your podcasts.

All right, Daniel, we're talking about the DMA experiment in Italy who have been claiming for 20 years that they found dark matter, but nobody believes them. And so they have a big vat of crystalline soda, underground, shielded, and they've seen it maybe interact with dark matter. So what exactly have they seen? Yeah, so what they see is really striking because what they're looking for are these little flashes of light.

But of course, dark matter is not the only thing that might give you those flashes of light. You could have like radioactive decay in the rock. This thing is underground in the Grand Saso mind in Italy. And, you know, the rocks nearby can have a little bit of radioactive decay or muons can penetrate the rock sometimes and get all the way down to your experiment. So you have some sources of background that are not dark matter. Isn't it shielded? Don't they put it behind big, thick walls or something? Yeah. And first of all, they buried it in this mine under like, you know, miles of marble and granite, which is awesome shielding. But then, yes, absolutely, they have things

surrounded by concrete and they have fiberglass. They do their best to shield it, but you can't always shield things completely perfectly. There will always be some level of background. So what they do is they look for something that only the dark matter could do, a signal that would look different if it was dark matter or if it was one of these normal everyday backgrounds. And the idea they had is to look for seasonal variations. Like in the fall, it tastes a little bit like pumpkin spice and then in the winter it tastes a little, in the spring it smells a little bit like flowers? No, they have this idea of taking advantage of the fact that the earth is moving through the dark matter at different speeds.

And when we move through the dark matter at higher speed, they should see more dark matter interacting with their detector. And when we move through at a lower speed, they should see less dark matter interacting with their detector. And that's just because we're going around the sun. And so sometimes we're moving more with the dark matter and sometimes we're moving more against the dark matter. It's kind of like this old idea of the ether, kind of, isn't it?

You know, if we are in a big cloud of dark matter and the sun and the earth is moving through it as we go around the sun, then, you know, sometimes we'll see it going one way and another times we'll be seeing the dark matter fly by another way. Yeah, it's very similar to the idea of the ether in that there's sort of a rest frame, right? We don't know exactly where the dark matter is, but we imagine it's pretty smoothly distributed through the galaxy. Again, we don't know that it might have clumped, but dark matter is very slow moving, and so we think it's pretty diffuse. We think it's pretty much spread out. We also don't know how fast it's rotating. We think it's rotating around the center of the galaxy, just like our kind of matter is. But regardless of how fast it's rotating, you can imagine some rest frame for the dark matter.

And then the Earth is moving in that rest frame because it orbits the sun. And so some part of the year it's moving through it faster than other parts of the year. So their idea is, well, let's look for that. If this is dark matter or not muons or crazy radioactive decay, or something else, then we should see a seasonal variation in our signal. We should see more interactions in June than in December. Because we're assuming that dark matter kind of has a velocity. And sometimes we're going against the current of dark matter and sometimes we're going with

the current. Yeah. Well, you don't have to assume that dark matter has a velocity with respect to the galaxy. It's our velocity relative to the dark matter that's important. So you can always just pick your rest frame. And if you pick your restroom as the dark matter, then our velocity through that dark matter has to be changing year to year because we're orbiting the sun.

And dark matter is not orbiting our sun. Right. But I think you have to also account for the fact that we're going around the galaxy, right? Because if we were just going around the sun, then dark matter was static, we would see it go the same speed by us. It would just be in different directions. It's more about the interactions with our rotation around the galaxy too, Right? Yeah, you can think about it that way.

You know, think about it like the Earth and the Sun are moving in the same direction relative to the dark matter or relative to the rest of the galaxy during part of the year and in the other part of the year, they're moving the opposite direction. So the Sun is moving around the galaxy in one direction and the Earth is going the other way because it's a different part of its cycle around the Sun. And so these velocities add up differently. Sometimes they add up to make a larger velocity relative to the dark matter. And sometimes they point in the opposite direction.

of each other, and so they make a smaller velocity relative to the dark matter. So like if you're just standing on Earth, you would sort of see dark matter sometimes flow past you really quickly and sometimes more slowly, like a dark matter wind. Yes, just like a dark matter wind. And so that's the idea is like let's look to see if there are more dark matter interactions in June than in December, because that seasonal variation would be what you expect to see from dark matter, which has this seasonally vision. varying velocity relative to the earth.

And it has nothing to do with pumpkin spice. Or maybe it wore shorts in the summer, too. Well, you know, nobody understands the results of this experiment. So maybe it is just the cumulative effect of pumpkin spice latte. Pumping spice espresso is because, you know, they're in Italy. All right, so they've seen a signal, basically, is what you're saying, is that they've seen a seasonal variation in their detection of dark matter according to sort of the motion of the earth, which might be like, hey, maybe it's

dark matter is there and it is seasonal. Yes, exactly. They are seeing this seasonal variation. If you look at a plot of their results, the sort of number of sparks they see is a function of the day, then you see it goes up and it peaks in June and it falls down and it minimizes in December and then it goes back up again. And, you know, they've been running this experiment for years,

which allows them to see lots of these cycles. And so it's not just like one little wiggle, which could have been anything. It's definitely a cycle and it's definitely annual and it definitely peaks. and dips in the right places. Wow, yeah, they've been seen signals for 14 years. Like, it's not a one-time fluke that they see the pattern. It's like they've been measuring this and it goes up and down yearly for 14 years. Yeah, for at least 14 years.

They've had a few iterations of this experiment. They've upgraded this. They've tweaked that. And so different plots have different numbers of years on them. But, you know, almost 20 years ago, they started seeing this signal. In the first few years, people were like, nah, keep taking data. We don't believe it. But now they have these plots.

just like wiggle and wiggle and wiggle and wiggle. And it's very unlikely that it's a fluke. You know, if you do the calculation, what are the chances of seeing this kind of wiggle from something which is actually flat? It's very, very small. The threshold for discovery in particle physics is 5 sigma, which means like, you know, one in millions of chances of being of background fluctuation. But they have 9 sigma, which is like almost unimaginable.

So this is definitely a signal. Something is happening here. The remaining question is, Is it really dark matter? All right. So they have 14 years of data. It's a pretty clear wiggle that there's dark matter, but nobody believes them. So what's going on, Daniel?

Do people just don't believe their data? Are they suspicious? Is it that nobody's been able to see it in the same way? What's going on? Well, there's a lot of things going on here. Some of them are technical and scientific, and some of them are sort of sociological and maybe personal. Some people don't like pasta. Everybody likes pasta.

Some people just don't put Parmesan on their shrimp pasta, which is, you know, unimaginable. That's a no-no. That's a yes, yes, for me. Anyway, one problem is that they have not really shared the details of their data. What? Like, they show up at conferences, they write papers, they show these results that look great, but they haven't opened up their box to show us like the nuts and bolts, how they analyze the data and shared a lot of details.

And as you can expect, physicists want to see details. You can't just show up with your one discovery. plot and say, look, we've discovered it, let's all move on. People want to dig into it and understand it and think about how to double check it. And they've been pretty closed with their data. Right. Well, it used to be that people were super closed, but I think the more recent trend is for everyone to just open up their, you know, files and let everyone sift through your numbers. Yeah. And, you know, extraordinary claims require extraordinary evidence. And so you have to, like, respond to questions and give details when people ask. You send a paper in for review, for

example, the reviewers can ask for more experiments or additional plots because what they want to do is make sure this is real, that it makes sense to them. It can't just be one pretty plot. It has to reflect something true about the universe. And so people want a consistent story, something that tells them this is really dark matter and not something else. So what's their excuse for not releasing the data? Are they under audit or something? I don't know. It's a bit of a cultural thing. You know, they show up at conferences and as one dark matter theorist described to me, they seem a aggressively uninterested in what other people think about their data. I think you're saying they're too cool.

They believe their result. They're very confident in it, but they haven't shared enough details for other people to really gain confidence in their results. And so instead, people have had to turn to other experiments which should be sensitive to the same signal to see if they can confirm it. Right, because maybe another experiment that with a similar setup, like with a vat of stuff waiting to interact with dark matter, would also see like these seasonal spikes. Yeah, you would expect so.

And in fact, one of the other big dark matter experiments in the world, the xenon experiment, is sitting in the same lab. What? Like they have this big hollowed out space under this mountain to do these kinds of experiments. And they gave part of it to the DOM experiment and part of it to the Xenon experiment. So the Xenon experiment is literally in the same place as the DOM experiment. So if there's any issues with like seasonal variations on temperature or something else, right? That's the concerns that there might be some seasonal source. of background that they haven't accounted

for. Xenon is in the same place. It's in the same lab. They do not see this seasonal variation. So nobody's seen this seasonal variation. There's several of these dark matter experiments, but nobody has seen this kind of variation with the year. That's right. There's a huge variety

of dark matter experiments. They have different like active materials like liquid xenon versus sodium iodide crystals. They're in different places around the world. They have different sensor technologies. Nobody has seen a result that's consistent with what Dama has seen. And so you might ask like, well, would they have seen these results? Is it possible for dark matter to only interact with this one kind of material and not the others?

And so people have built like boutique theories of dark matters to try to explain this Dama experiment, why Dama would see it, but Xenon wouldn't. Maybe it only interacts with neutrons instead of protons or prefers protons in one arrangement to another kind of arrangement. But nobody has been able to explain it. And in the meantime, people have built copies of the DOMA experiment that are essentially the same technology, the same active material, the same kind of sensors, but just in different locations to try to double check DOMA. Interesting. They've used like this crystalline sodium also and they've put it inside of a mine and do they see anything? They don't see anything yet. So there's an experiment in South Korea called cosine, and I have no idea what that stands for.

but they basically have duplicated the Dama's experiments set up, but they don't see the results. Now, this is a difficult thing to do. It takes years of data to say, are we seeing a flat line or are we seeing wiggles? So so far, they only have a couple years of data, and they say their results are in, quote, severe tension with the Dama results. But they also admit that it could be consistent with Dama. They just don't have enough data yet. So time will tell if cosine sees a wiggle or not.

But so far, the indications are that they haven't. Interesting. They want to see it happen before they co-sign the certification there. That's right. They want to see their own cosine in the data. They want to see their own wiggles. Yeah. All right.

But still, Dama is pretty confident about their results. Dama is pretty confident in their results. You know, they believe that it's dark matter. People have thought about all sorts of other sources of background. Like maybe the rock heats up in the summer and it gives off more radiation. and that leaks into the experiment, and they have all sorts of ways to monitor this, and they don't see that kind of thing.

So physicists in the community has spent a lot of energy brainstorming possible explanations for what might explain this other than dark matter, more prosaic explanations. And so far, they haven't figured out anything that they can point to

that says, here's why Dahma is seeing this signal. It's not dark matter. It's, you know, growth of plants on the top of the mountain is releasing something in June or something like that. But nobody's found that

explanation yet. All right, let's get into what maybe Dama is seeing in their signals of dark matter and why nobody believes any of these. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m. everything changed. There's been a bombing at the TWA terminal. Apparently the explosion actually impelled metal glass. The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and order, criminal justice system is back. In season two, we're turning our focus to a threat that hides in plain sight.

That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast. So, we'll find out soon. This person writes,

My boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor,

and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast.

I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast. Here's a clip from an upcoming conversation about exploring human potential. I was going to schools to try to teach kids these skills, and I get eye rolling from teachers or I get students who would be like, it's easier to punch someone in the face. When you think about emotion regulation, like, you're not going to choose an adaptive strategy which is more effortful to use unless you think there's a good outcome as a result of it if it's going to be beneficial to you. Because it's easy to say like, like go you, go blank yourself, right? It's easy.

It's easy to just drink the extra beer. It's easy to ignore, to suppress, seeing a colleague who's bothering you and just like walk the other way. Avoidance is easier. Ignoring is easier. Denials is easier. Drinking is easier. yelling, screaming is easy.

Complex problem solving, meditating, you know, takes effort. Listen to the psychology podcast on the IHartRadio app, Apple Podcasts, or wherever you get your podcasts. All right, Daniel,

the DOM experiment has been seeing a dark matter signal for 14 years, but nobody believes them and nobody can replicate their results. So what are some of the possibilities here's of what they could be seeing? Do they have like a wire that's not connected right, but only once a year? Or is it could be the air conditioning in the room that, you know, in the summer it kicks up more or what could it be? Yeah, so there's sort of two categories of

possible explanations. One are non-dark matter explanations, right? And ideas there are like they use nitrogen in their experiment, but it also has a little bit of argon in it. They surround the experiment with Argon and it could be that some of that Argon has seasonal variations in it that's more activated during June than in December based on based on what how would the Argonne know what this season was well it's not that an individual Argon Adam knows the season or like celebrates Christmas it's that the amount of radioactive Argonne around the experiment depends on the season the contaminant we're interested in here is Argon 37 which is made when New Yorkeractive. neutrons hit calcium in the soil or argon 36 in the atmosphere and the neutron flux the number of

neutrons coming in to make argon 37 has a seasonal variation due to the variation in atmospheric density which determines like how many make it all the way down but you know people are really scratching their heads trying to think of crazy explanations because of course the folks at dama are solid physicists and they've taken care of all the obvious effects that have as much you know climate controlling as they can manage in this environment to try to isolate themselves from any sort of seasonal variations. But you know, at the colliders, we're also sensitive to really, really tiny effects. The phases of the moon affect the shape of the rock near Lake Geneva. And that affects the bending of the accelerator because it's under the rock.

And people notice these things. What? You see tidal effects in your data? Absolutely. The train schedules in Geneva affected the results of colliders in those tunnels. And so we can be very sensitive to very small effects. What? How did the trains affect the particle collisions?

Is it like the vibrations of the trains or just more people on campus at certain times? It's really amazing, actually. It was the electricity from the trains. Some of the extra current leaks down and made little gentle magnetic fields, which actually influenced the operation of the collider. And so when you're hunting down tiny little explanations and you're trying to separate the ideas from like dark matter to other basic prosaic explanations, you've got to go all the way down the list for really small effects.

Wow. All right. So what else could this signal they're seeing? What else could it be? Could it be, you know, some other kind of theory about how dark matter interacts? It could certainly be. Like there could be other ways that dark matter interacts. It could be that dark matter is something weird that we hadn't imagined before.

And that's why we're seeing it only in these crystals but not in others. Now the cosine experiments and the other ones that are replicating this make it pretty hard. to follow that kind of explanation because they're basically a copy of DOMA and they don't see it. But put those aside and let's say maybe cosine and the other experiments that are trying to replicate it just don't have enough data yet. People have cooked up theories that try to explain why dark matter interacts with sodium iodide more than it interacts with xenon, for example. Like maybe dark matter prefers Italians or, you know, less to vacation in Italy more than it does in South Korea. Yeah, and it also has to do with the mass because xenon is head.

heavier, for example, than other elements. And so dark matter is very, very low mass. If it doesn't have a lot of oomph to it, then it might be that it's just harder for it to push xenon than to interact with sodium iodide. And so people have come up with these theories of like very light dark matter. But those theories are also hard to explain because Dama built a new system in their experiment, one that should be sensitive to sort of lower energy results.

And they don't see any difference in the low energy results and the original ones. And if there was very, very light dark matter, they would expect to see a larger signal in these low energy recoils, but they don't. So people spend a lot of time trying to construct these fancy dark matter theories that could explain Dama as dark matter, but none of them really hold water. So the consensus in the dark matter community is that Dama is not seeing dark matter. They're seeing something else. We just don't know what it is yet. I guess the problem too is that as we go around the sun, it's not just about more sunlight or less. sunlight. It's also kind of there's other stuff going out there in space, right? Absolutely. There are

variations in like how many muons strike the earth because muons come to the earth from cosmic rays and not just from the sun, but also from galactic sources. Like there are muons being created by other stars and from the galactic center that hit the earth. And so that varies also with the seasons for similar reasons. And so it could be that they're seeing some weird dockoff effect from these cosmic muon seasons. It could be that. Nobody's really nailed that down yet. All right.

So the consensus is that they're not seeing dark matter, but have they told Dama that everyone thinks so? Or is this just sort of a like a background whispering like, I don't think they've seen it? Dama is definitely aware that their explanation is not accepted. But they are very confident, you know. They are sure that their experiment indicates the presence of dark matter particles in the halo. There's a quote from the longtime leader of the experiment saying there is no alternative explanation for our signal.

Wow. So they're very confident. They are aware that nobody believes them, but they are powering forward, you know? Wow. What do you think, Daniel? Are you aggressively interested or aggressively uninterested in this result? When I first heard about it, I was super excited. I was like, what a beautiful signal.

What a nice experiment. I would love to believe it. But, you know, before you believe something like this, you really have to see it replicated because we're not interested in one cute story of an experiment that sees a cool wiggle. We're interested in the actual story of dark matter. And if it's a real story of science, it should appear in more than one place. You should be able to see it using more than one technique or you should at least be able to tell a coherent story about why it's here and not there. Because the universe we think is a coherent story and so we should be able to pull it apart by looking at it from different angles. And this is so difficult to see that you really have to see it in more than one place before you believe it.

Right. You don't want it to be weak pasta, right? That's right. And so there's another experiment being built in the southern hemisphere, in the Sabre experiment. And it's very similar to the Dama experiment, except, again, it's in the southern hemisphere. And so it should have the opposite seasonal related systematic uncertainties. What? Because it's cold when Dama is warm, and it'll be warm when Dama.

is cold. If it's not related to the dark matter, but if it is, it should see the same seasonal changes, right? Because it's moving along. It's about the movement of the earth. Exactly. And so it's just another cross-check.

Like, let's move all temperature-related things off by six months. The dark matter shouldn't change at all. So if they see a signal and it's shifted, that suggests that it's a temperature seasonal variation thing. If they see a signal and it's not shifted, then that removes a lot of the possible explanations for temperature variations. It doesn't change things like, you know,

cosmic muon seasons, but it helps us sort of isolate what this might be. Right. And did they find anything? They're still building it. And so we don't know the results of the Sabre experiment. It's being built in a gold bind in Australia. And everybody's very eager to see what that experiment has to say.

All right. So I guess the answer is stay tuned. I guess nobody believes the Dama experiment because it hasn't been replicated. And it could still be other things that cause it. the signal. That's right. There is no coherent explanation in which Dama is seeing dark matter and somehow nobody else is able to see it. And so the most likely explanation is that it's some weird source of signal that they haven't isolated yet. But it could still be. It could be that

there are pockets of dark matter or the dark matter is interacting with some weird kind of matter that only exists around the Dama experiment in Italy for some weird reason. But you have to have sort of crazier and crazier thoughts to explain this and to explain the lack of signal. and all the other experiments. I see. I guess it's sort of the challenge for both sides of people trying to prove this data, right? Like it's getting harder to come up with excuses, but it's also getting harder to replicate. Yeah, absolutely.

But it's also a fun puzzle. If you're an experimentalist and you like to dig around in the data and understand where is this coming from, why is it look this way and not the other way. It's not a deep mystery of the universe, but it is a fun question to ask, like, what could be the source of this? It's a nice little detective mystery. and the person who actually figures it out eventually might not win the Nobel Prize, but they will scratch long-standing itch in particle physics. A dark itch.

A dark itch that really matters. All right, well, stay tuned, and maybe in the next couple of years, we'll hear news about whether it's real or not, whether they deserve the Nobel Prize or just a nice dinner with a nice glass of Italian wine. And plenty of Parmesan sprinkled on top. All right, thanks for joining us. See you next time. Thanks for listening and remember that Daniel and Jorge Explain the Universe is a production of IHeartRadio.

For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, everything changed. There's been a bombing at the TWA terminal, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of season. of law and order criminal justice system on the iHeart radio app apple podcasts or wherever you get your podcasts

why are tsa rules so confusing you got a hood of you want to take it all i'm manny i'm noah this is devon and we're best friends and journalists with a new podcast called no such thing where we get to the bottom of questions like that why are you screaming i can't expect what to do now if the rule was the same go off on me i deserve it you know lock him up Listen to No Such Thing on the I Heart Radio app, Apple Podcasts, or wherever you get your podcasts. No such thing. I'm Dr. Joy Hardin Bradford, host of the Therapy for Black Girls podcast. I know how overwhelming it can feel if flying makes you anxious.

In session 418 of the Therapy for Black Girls podcast, Dr. Angela Neal-Barnett and I discuss flight anxiety. What is not a norm is to allow it to prevent you from doing the things that you. want to do the things that you were meant to do. Listen to therapy for black girls on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. This is an IHeart podcast.