Into the Impossible With Brian Keating - What Is Dark Matter Really Made Of? (#396)

Episode Date: February 23, 2024

Please join my mailing list here 👉 https://briankeating.com/list to win a meteorite 💥 Remastered from our interview in 2022.  There are few concepts in physics as frequently discussed but as poorly understood as dark matter. After all, we don’t even know what it’s made of!  However, there are many potential candidates, and I had the pleasure of explaining them in my interview with Arvin Ash. We also talked about the fascinating possibility of detecting gravitational waves from the polarization of the CMB and why it is very likely that there is, in fact, no life outside of Earth.  Tune in! Key Takeaways: 00:00:00 Intro  00:00:37 What is the CMB? 00:01:25 What is the polarization of the CMB? 00:04:49 What is the evidence for cosmic inflation?  00:05:46 What is the leading contender for dark matter? 00:11:51 There may be no other life in the universe! — Additional resources: ➡️ Check out Arvin Ash: 💻 YouTube: https://www.youtube.com/channel/UCpMcsdZf2KkAnfmxiq2MfMQ  ✖️ Twitter: https://twitter.com/arvin_ash?lang=en 📝 Get one month of Snipd Premium for free with this link: https://get.snipd.com/Cx7S/brianSnipd Snipd lets you take Smart Notes 🧠 with AI 💡 — it’s my favorite podcast player 😀 ! 📢 Ownership of your health starts with AG1. Try AG1 and get a FREE 1-year supply of Vitamin D3K2 and 5 FREE AG1 Travel Packs with your first purchase 👉 https://drinkag1.com/impossible ➡️ Follow me on your fav platforms: ✖️ Twitter: https://twitter.com/DrBrianKeating  🔔 YouTube: https://www.youtube.com/DrBrianKeating?sub_confirmation=1  📝 Join my mailing list: https://briankeating.com/list  ✍️ Check out my blog: https://briankeating.com/cosmic-musings/  🎙️ Follow my podcast: https://briankeating.com/podcast Into the Impossible with Brian Keating is a podcast dedicated to all those who want to explore the universe within and beyond the known. Make sure to subscribe so you never miss an episode! Learn more about your ad choices. Visit megaphone.fm/adchoices

I have a video on my channel, I don't believe in gravity. I have evidence for gravity. You don't need to believe in something you have evidence. We have no evidence for life in the universe. And we actually have evidence through what's called panspermia. And there's no evidence for life from Earth on Mars. So life is very touchy. I think it's very difficult.

I'm not arguing, you know, God, this, that. I just think the probability of it's very low. Certainly for technological life, the bar is so much higher. Any sufficiently advanced technology is indistinguishable from magic. Open the pod bay doors, how? Well, I study the cosmic microwave background radiation, which is the oldest fossil heat left over from the Big Bang, and it traces the composition, the properties, the evolution,

and perhaps the origin of the universe could be revealed in it. I like to think of it as kind of, remember those old-fashioned films, you know, used to take to the drugstore, and you'd have them exposed and so forth. So the CMB is actually like a type of film, onto which we hope to expose waves of gravity if indeed the universe began with an inflationary epoch because I know you've talked about in the channel many times.

So it's really a detector and it's a signal. So it's kind of unique in that way. And so I find it fascinating. I think it's the most interesting thing you can study, but I'm kind of biased. It's been my whole career. Yeah, so polarization is the unique interaction between light and matter that can be traced

to determine either. the properties of the light or the properties of the matter. So if you've ever used polarized sunglasses, you know that they suppress one of the two linear polarization states of light. The light is a transverse wave. It means it oscillates up and down as it progresses in a direction from the source to the observer. And when it interacts with matter, it can get some of the imprint of the light source can be change by the properties of the matter, either what it's made of or how its dynamics are behaving.

So in the case of the cosmic microwave background, we have this early universe as a fusion reactor, as a soup of primordial plasma. And if there were waves of gravity in it, the photons that are in the plasma, as they interact with the matter and bounce around, they will inherit some of the properties of the underlying space time in which the matter is contained. So it's kind of a diagnostic. The polarization uniquely allows us to see the imprint of the, perhaps the impact of these waves of gravity. And what's so exciting is we know since 2015 that waves of gravity exist thanks to LIGO.

And LIGO measures objects that billions of light years distance billions of years ago. So we're trying to measure 13 billion years, 13.8 billion years ago, when the first matter really came into existence. So it's a lot more challenging to do. And as far as we know, this is the only way to use the technology that's available in the foreseeable future. We can only detect these waves of gravity using the CMB itself. And the waves of gravity will only be there if inflation took place. There are no other models that predict robustly so a background of waves of gravity in the early universe. In other words, a cosmological background.

The black holes that Ligo detects those waves, those are astrophysical sources. Those are not cosmological. Those are not coming from the Big Bang or from the origin of the universe in any sense. They're very interesting. They're exquisitely beautiful laboratories for learning about gravity. We want to learn about the universe using those waves of gravity as our tool. There will be C&B polarization, but there won't be this type that reveals the presence of gravitational waves. That will be absent in all models except for inflation.

Hello, Students of the Impossible. It's Professor Brian Keating here with just a tiny little homework assignment to interrupt your podcast. And that's to make sure that you're subscribed to the podcast or following us on your podcast app of choice. I did some research and actually only about 50% of you are actually following or subscribing. to The Into the Impossible podcast. And really mean a lot if you could subscribe and keep up to date with me and with all the greatest content. I'm putting out tremendous amounts.

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Thanks a lot. Now back to the show. So inflation has a lot of circumstantial evidence for it. It has a very good ability to reproduce some of the most kind of baffling aspects of cosmology. There's many pieces of evidence for inflation that are supportive of it. It hasn't been ruled out. It could have failed certain tests already. It hasn't. For example, we say the universe is flat, meaning that any three points in the universe, no matter how far away they are that comprise a triangle, the interior angles inside that triangle will add up to 180 degrees,

just like they did for Euclid on a piece of paper, you know, 2400 years ago. Dark matter really can fall into two different categories. It could be a new form of matter, completely unlike the barionic matter that we're made up of, the ordinary matter that we're made up of. It could be a modification of our understanding of gravity. Those are the two main classifications of what, potentially could be happening. We actually know of one form of dark matter.

I have a video on my channel about this, dark matter has already been detected. Because there is a form of matter that has mass, that is abundant in the universe, and doesn't interact with matter, including and doesn't produce or generate or interact with light. And those are called neutrinos. There's actually trillions of them going through each one of us right now.

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They don't decay, but they oscillate and they change their flavors from one kind to another kind as they travel. They behave differently in highly dense media. They're participating in radioactive decay, but they don't interact with light. And they have very, very, very, very, very tiny masses. I have a video out about the first laboratory measurement to get to below what's called one electron volt of energy. I know your viewers know are very conversant. because you always talk about what's an electron volt.

So an electron itself has a mass, according to equals MC squared, a 511,000 electron volts. The neutrino mass measured by the Katrin experiment in Germany has to be lower than one electron volt. It can't be any bigger than that or they would have seen it. It's called an upper limit. We also have a, from neutrino oscillation experiments, we know there's a lower limit.

The neutrinos can't be. smaller than a certain mass limit. Well, that mass limit is 15.1,000th of an electron. So the electron, which is the lightest of the common elementary particles, is millions or maybe billions of times heavier than these neutrinos. And yet we don't know their exact mass. So that's a form of dark matter of a material kind. Turns out that's not sufficient to account for the observed amount of dark matter there is. We don't know what it is, but we know how much of it there is. If it's matter, if it's in the form of these types of particles. So there are many, many projects currently undergoing measurements now to look for what are called weekly interacting massive particles or wimps.

We've ruled out in the last two decades, we've ruled out primordial black holes as being a type of dark matter that account for how much we see. We see about five times more dark matter than ordinary matter like protons, neutrons, or my favorite particle, the crouton. It's only particle like you eat. So those particles are outnumbered five to one by dark matter. And then dark matter and matter are outweighed by about two to one by dark energy, which we know absolutely nothing about. So there are many people, including our cosmic microwave background experiment,

the Simon's Observatory, that are looking for both ordinary neutrinos and trying to get their masses cosmologically. And we're also looking for exotic particles called axions, which are kind of like heavy photons, but they're not photons, they don't interact with light. So I would say those are, and those are conjectured by physicists here in California, and Frank Wilczak has made a lot of good contributions to that as well, Pachain Quinn, were the original two kind of founders of this. So this axiom is a good candidate. And then on the changing gravity, there's a whole other theory called Mond, modified Newtonian dynamics, which says that on galactic scales, you can't even use Newton's laws.

You have to modify those. And the laws of relativity that recapitulate those need to be modified as well. And we just don't know right now. There's a lot of evidence. I would say most of my colleagues believe that Mond is incorrect because it can't account for several things like these colliding galaxies behind my shoulder over there, the two galaxies in the whirlpool. there's certain galaxies called the bullet cluster. It can't account for how they're interacting appropriately.

But then other supporters of Mond will point out, well, the ordinary model can't predict for the high velocities that these two galaxies are merging at. So it's a very interesting and open question. And I think the most dangerous words are, you know, what's your favorite, you know, choice? The best thing to do is that, I mean, it's actually a good thing because that means that there's multiple angles of experimentation

that my team and I can look for to explore this. So we can see neutrinos, which would be kind of matter particles, but we could also potentially detect violations of relativity as well. And actually, you know, no one would be happier than someone like me if we discover that relativity is wrong on cluster scales or, you know, intergalactic scales. Because that is just, you know, incredibly fascinating. And the whole all of modern physics is underpinned by aspects of

relativity or what's called Lorenzen variance. And so there's a lot more speculation that could be had. And again, my job, like where I get my most, where's my happy place? You know, where do I get enjoyment? It's from, it's from like making, getting a number, a data point that's the result of years, perhaps of building hardware and blood sweat and tears by me and my students and my team. And then getting this number and then saying, well, this now tells us something we never knew about the universe and tells us how we were wrong in what we used to think. So I can't take sides. Either one would be really interesting, right? I mean, are there some new particle that is like maybe there's a dark periodic table?

Maybe there's like this shadow world of non-existent... Super symmetry, maybe? Yeah, it could be super symmetry. Or, you know, maybe there's a modification that Einstein was wrong yet again. You know, he had like, you know, seven pretty big blunders in his life. And again, he ended up, you know, with tenure. So that's okay in my book. But, you know, he could be wrong. He wasn't a nobody.

Yeah, he wasn't a nobody. I'm kind of a contrarian about it. I don't believe there's life in the universe. So I didn't interview with Lee Kronin. I've done interviews about aliens with some of the biggest proponents of aliens. I believe right now, if you had to just weigh the evidence, that's insufficient to say the capacity for life is overwhelmingly dispositive. that there is life.

And I give the example of Antarctica, where I've been twice. Antarctica is one seventh of all the continents on Earth. It's in terms of total land mass. It's even larger in some sense. It's peak pollination season, and my business is scaling fast. To keep the nectar flowing,

I need a phone plan with top priority data speeds. That's why I chose GoogleFi wireless. My connections stay strong even when the hive was buzzing. Plus, unlimited plans started $35 a month. Now that's a deal that's a deal. doesn't stay. Explore GoogleFi wireless plans today. Plus taxes and government fees. GoogleFi Wireless is not subject to data traffic deprioritization during times of high network usage. We didn't know about Antarctica for, you know, thousands of years, discovered it. There's like no

life there. But if you just purely said, life depends on how much available phase space there is for, and life can exist there. There's birds and fauna and stuff. But it doesn't. It really doesn't exist. there's no intelligent life, et cetera. Again, it's not based on what I believe. I have a video on my channel, I don't believe in gravity. It's called, I have evidence for gravity. You don't need to believe in something you have evidence. We have no evidence for life in the universe.

And we actually have evidence through what's called panspermia that meteorites travel through our solar system. And there's no evidence for life from Earth on Mars, even though there's meteorites on Mars from Earth. So life is very, it's very touchy. I think it's very difficult and not arguing, you know, God, this, that. I just think the probability of it's very low. Certainly for technological life, the bar is so much higher.

So imagine you say there's 10 different things that needed to happen to have life on Earth so that you and I could have this conversation. The universe has to form. Solarisism has to form. And then you have to go from hydrogen and carbon and silicon. And eventually you have to get DNA and everything. Then you have to survive this. late heavy bombardment, the earth was pummeled.

Then you have to have dinosaurs that are roaming around. And then dinosaurs have to be killed off. Then you have to have enough, you know, biotic matter to make oil, to make semiconductors, to make the transistors that make the computer that you and I are talking on. Again, I'm never going to say there's no life. I'm just saying there's no evidence for life. Okay.

And I'm not sanguine that we're going to rapidly find evidence for life. In other words, the hype surrounding existence of not only, remember, what's being claimed is that we're visited by alien technology. My friend Alvi Loeb and others have, you know. So again, I skipped the head to that. But to get there, say there's 10 things that have to happen, even for slime mold. You know, if you find slime mold on, you know, Proxima Centauri B, the different hurdles that that planet would have to sustain to get to that point. Let's say there's 10 of them. And let's say each one has a probability.

of one in a thousand. So you have, you know, that means you have a one in 10 to the 10th chance of life happening on that particular planet. That's about 10 billion, you know, to one. Now, I think there's a lot more than that. You know, you need to have RNA or maybe do you need DNA for, you know, how does all this stuff come together? How do you have enough nutrients?

How does it survive? All these different things for there to survive to be there. And again, as I said, I don't know if you remember in 1996, there was a pre-196. there was a press conference held on the White House lawn. It's actually featured in the movie Contact, which is written like Carl Sagan and one of my guests, Andrewian, his widow. And that's a real video. President Bill Clinton is saying,

we've discovered this amazing signs that scientists say could be like that was peer-reviewed, accepted, had to do with meteorites found on Antarctica's continental shelf that originated from Mars. And there was a Martian meteorite that had allegedly byproducts of respiration. Arvin, do you know that that's never been retracted? That paper, the conclusion, I've never been retracted. It's never been confirmed.

And so you have this thing standing out there for the last 30 years almost. That's never confirmed. And it's like people think of it as the most important thing in human history if it were true. In other words, we're always looking to the future. Oh, we'll find life next week, next month, next year. But we already have this thing. And, you know, yes, the average human being, they don't know anything about it.

And all I'm saying is that the, you know, the conditions in which life originates ab initio are exquisitely well-tuned. And some of them were done by people that used to be at UC San Diego, Miller and Yuri, and their famous chemistry, early Earth chemistry experiment. There's been very little progress in that front. And there's a lot of kind of talk about things like extremophiles and other types of life.

And even people like, you know, Max Tagmark and others talking about digital life. Like, when I'm going to have, forget about like, slime mold, there's going to be like artificial intelligence is busy. preponderance of the universe, or even as one of my guests, David Charneler said, we're in a simulation. So you see the goalposts shifting, which to me as a scientist tells me the bedrock foundation may not be that stable. Own it all. Pay off your home, travel for life, drive a Ferrari. In celebration of the world premiere of the Monopoly Big Board Buckslot machine by aristocrat gaming, Yamava Resort and Casino at San Manuel is giving one person a $1.6 million dream package.

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