Chapter 1: What is the main topic discussed in this episode?
We are growing our stable of cosmologists. Yes. Got Katie Freeze coming in. That's right. Tells about dark matter, dark energy, Big Bang, rockin'. Yep. The only cosmologist who sounds like a Batman villain, Katie Freeze. Coming up on StarTalk. Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk.
Neil deGrasse Tyson, your personal astrophysicist. This is going to be a Cosmic Queries edition on cosmology. There's no end of Cosmic Queries we can do on cosmology. I suppose there is not. This is Chuck Nice right here. That's right. Professional comedian, stand-up comedian. There is an end to me. So cosmology. Yes.
So we're broadening our stable of cosmologists to whom we can reach out for our queries. Right. And today we have a second timer. That's right. The one and only Katie Fries. Katie, welcome back. That's right. Yay. Welcome back to StarTalk. Thank you. Thank you. Last time you were here, I think we talked about the search for dark matter. And- We did. We did. We did.
Because that's cosmology writ large. And we poked your brain about all manner of things. And this is going to be a Cosmic Queries where we have told our Patreon supporters that you're going to be on. and they're fans of yours, and they've written in, or they became fans of yours when they saw your expertise. That's right. And they wrote in, and the questions are here. Well, thanks a lot.
I haven't seen these queries. Well, neither have I. He's the only one who's seen them. Yes, okay. And I'm the only one who can't answer them. That made me drool. That is kind of funny. The only people who can't answer them haven't seen it. And the one who can't answer it has. They haven't. So a couple of times people have asked questions that no one has been able to answer.
Like with the quark one going into a black hole. Quark into a black hole. We still don't know the deal. We still don't know that one. Maybe Katie knows. We can find out. We should find out, yeah. But let me get your bio here. Director of the Weinberg Institute for Theoretical Physics, UT Austin. That's Stevie Wonder, Steven Weinberg. Yes. Right?
So Steve Weinberg, my hero, one of the founders of the standard model of particle physics. Yes. He was the greatest physicist of our time, in the opinion of many, including me.
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Chapter 2: How does Katherine Freese explain dark matter and its candidates?
His office was three doors down from me. He recruited me to UT Austin. Maybe that's why I think he's the greatest living physicist. That helps. Who gave you the good job, right? Yeah, yeah. No, seriously. It was only named in his death, obviously. Yeah, he died about three years ago. Yeah, okay. And we started the institute in his honor. And now he's more a hero for me than he is for you.
Why is that? Because he went to my high school. Oh. Bada-bing! Oh, Bronx Science. The Bronx High School of Science. Oh, yeah, yeah, yeah. Both he and Shelly Glashow were in the same class. They were classmates, and both shared the Nobel Prize. Okay, so the moral of the story is, when are you getting your Nobel Prize? I didn't mean to set it up that way.
That was not... So what else do I have here? And you spent some time at Stockholm University, and that's ending, coming up very shortly? Ten years. They gave me a really... The Swedish government gave me a $15 million grant over ten years to do cosmoparticle theory. And that was so much fun. Wow. Oh, wow. Did you have students, too, and everything? Oh, I did. With a budget to go back?
I did, yeah. So I had students, and I had postgraduate fellows, and everybody running up and down the halls, having great ideas and having fun. It was awesome. Wow. Yeah. Okay. Because I think when we last interviewed you, you were like fully up and running with them. And what else? Oh, and I'd love this. Back now 10 years ago, the Cosmic Cocktail. Ooh. Can you get a better title than that?
Shake it nice and dark. I don't think so. Three parts dark matter. Ooh. Yeah. That's about right. That's pretty cool, man. You know, the amazing thing about that book is that I still give public lectures about it and people are still buying lots of them. In fact, Amazon ran out again. Whoa. And that was a book I wrote 10 years ago, so I guess it was a good one. Whoa. And you wrote a blurb for it.
You said, what did you say, I don't know, three parts Dark Matter, seven parts memoir or something like that? Oh, right, because it was folded into your life. It was, yeah. Yes, very important feature of that. Thanks for reminding me. It just made it a much more interesting account. Yeah, yeah. Right, right, cool. Here's another plug for it. Thank you. May Amazon run out again.
So, we're going to chat for a bit before we go to Q&A. Okay. Catch us up on a couple of things. The James Webb, there's been a lot of talk about these early galaxies that it has discovered in a zone of the early universe where you're not supposed to. So, wait, you're talking about the James Webb Space Telescope? Yeah. Yes. Yeah, not the administrator of NASA during the 1960s. Yes.
After whom the telescope was named. Yes. You know he was an accountant? James Webb? Yeah. One of the rare non-scientists after whom a telescope is named. An accountant. I think that was his main training. That's pretty wild. I gotta say. I guess he was... What was he important for in NASA? What's wrong? Was the head of HR taken? While we went to the moon, he was head of NASA.
So it was a give a little back to that. Look at that. Because you need good administrators, not just good scientists to make stuff happen. Well, you're a damn good administrator when they start naming stuff after you. So what's this we hear about paleo detectors? What is that? Is that a thing? Yeah. What is that? Well, the paleo part means that they've been around for a billion years.
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Chapter 3: What are the implications of the James Webb Space Telescope findings?
Well, can we borrow your olivine to look for dark matter tracks, please? You got to know somebody. Okay. You got to know somebody who works here. Thought I did. Yeah, no, we can totally explore them. They could be the key sitting under our noses. It's been here for 25 years. Well, then it's been collecting cosmic ray tracks. Oh, yeah, no, we didn't have it. Sad. Yeah.
Do you guys have any, like, deep under the earth here? Like, is there a... But it still has to get through the building. Yeah, we want to know about the sub-basements of this building. It still has to get through the building, though. The cosmic rays have to get through the building. Yeah, well. That'll block some of them, right? Nah. All right, so congratulations on this. Thank you.
This is now a burgeoning next step in this. So why a billion years and not 100 million or 50 million? Does it matter? Well, we have to go deep enough to get away from cosmic rays, and that's actually like five kilometers. Oh, that's deep. It's deep. And then the other idea is if we get rocks from different agesā We also can study neutrinos, because neutrinos will also leave tracks.
The tracks will be different, okay, so you can tell the difference. But then you can figure out how many supernova went off in the galaxy, if you look in the past, a different amount of time. Isn't that cool? Wow. And that is because the supernova, that's where the neutrinos come from. Copious immunity. Oh, I forgot to say that. Yeah. Neutrinos give off a lot of supernova. No. No. No, no, no.
Supernovae give off a lot of neutrinos. Supernovae, which are dying, exploding stars. And you can look for the neutrinos from the supernovae. Right. Cool, man. And neutrinos are, once again, your weakly interacting particles. Yeah, they are also weakly interacting particles, yeah. Most unfortunate. Now, the other thing you can do is with... Weakly interacting particles, yeah.
Well, we know who named him that. Who named him? I forgot. Mike Turner. Is that right? Mike Turner. That would have made sense if you said Ike Turner. Whoa! The word eponymous comes to mind. I'm Nicholas Costella, and I'm a proud supporter of StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson. So I got one more question before we go to Q&A.
Some of the results of the James Webb Space Telescope and other sources suggest that we cannot reconcile the age we have derived for the universe by these different methods. One of them is from the CMB, cosmic microwave background. Others is from galaxies at other times. And it has been suggested that you can reconcile them if dark energy changes over time?
The biggest evidence for dark energy changing over time comes from a different experiment, the DESI experiment. Okay. And what they're looking at... Lucy and DESI? No. Dark matter, you got some explaining to do. Oh, that's good. That's good. But DESI, so other than Lucy and DESI, what does DESI stand for astrophysically? The Dark Energy Spectroscopic Instrument. Okay, all right, clean and simple.
And what does that tell us? What they're looking at is based on some physics from the early universe, and there were waves which froze out at the same time the cosmic microwave background was produced. That's 400,000 years after the Big Bang, which is like, I don't know, a thousandth of a percent of the age of the universe today.
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Chapter 4: How do scientists study dark matter indirectly?
Did you read the body language? That was a very... Oh, no, I'm sorry. No, he's still learning social cues. I meant the opposite. Okay, cool, yeah. I'll tell you this much. He's right. That is Nobel stuff right there, man. That's fantastic. Wait, so the... You know, the thing about Astro, about my field, is that you can have a great idea. And, you know, let me back up.
Usually, when you have a great idea, you kill it in 10 minutes because it violates some observation. Occasionally, it not only survives those first 10 minutes, but then people start telling you, did you know you solved this problem? Did you know you solved that problem? And that's what's going on here. We keep solving problems. Mm-hmm. So dark stars could explain a lot of things.
They could explain, once they die, the supermassive black holes that you see in the early universe. They could explain the blue monsters, and they could explain the little red dots. And I figured you'd like those terms. Wow. These are all very bluntly descriptive stuff we see in the early universe. Because there's nothing nearby that we have a counterpart to. It's a red dot. It's a red dot.
Okay, so we call it a red dot. Now what about the blue monster? Ah! Way to get that reference. Blue monsters are really, really, really bright objects way early in the history of the universe. Yeah, it should be like the formation of galaxies. I mean, we know they're blue. They don't look blue.
They look very infrared because that blue has been redshifted to the sweet spot of the James Webb telescope. Yeah, yeah. Oh, that's very cool. All right. Okay, well, hey, what a great question, Anthropocosmic Dylan. So she said she's coming back after her Nobel Prize. Oh, absolutely. Now, here's the next question. Can I wear your Nobel Prize when you come back?
So here's the best line related to that. It was from Hoop Dreams. Do you know the line? I don't know the movie. You know this line? You know the movie? I don't think I know Hoop Dreams. Hoop Dreams. Go ahead. Dude, it's a documentary. You don't know Hoop Dreams. I do not know Hoop Dreams, but go ahead.
Yeah, it's a documentary of following high school students, some who have ambitions to play in the NBA. Oh, okay. Okay, and the social dynamic that surrounds it. It's a documentary. But here's the line. When you're rich and famous... will you remember us? As one of them goes off. And he says, if I'm not rich and famous, will you remember me? Damn. That's good. That's good. That's rough.
That's really good. I'm going to tell you the answer to both those questions is no. The answer, no. And to both. All right, let's move on. This is Nate. And Nate says, hello, Dr. Tyson, Dr. Fries, and Lord Nice. This is Nate from Southern Idaho. If dark energy has gravitational effects on everything just like regular matter does, why does it not coalesce and push away from itself?
This seems counterintuitive considering the fundamental nature of gravity is to pull things together by bending space-time. Does dark energy abide by its own rules where it can cause gravity but it isn't affected by it? This would imply that it is not influenced by the curvature of space-time in which it causes. This guy did some thinking here. Frickin' Nate, bro. Whoa. Dude. Whoa.
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Chapter 5: What are the differences between dark matter and dark energy?
No, it is a type of dark matter. It's a type. That's the answer. That's the answer. It's a type of dark matter. Since dark matter is invisible and hard to detect directly, what indirect properties or effects of dark matter are scientists currently studying and by what methods? I love that. Like, yeah. So what's the deal? It doesn't interact with anything. How are you guys measuring it?
How are you figuring out anything about it? You know, the thing about dark matter is we've got about 20 different candidate particles that it could be. Okay. Some of them are well motivated and some are not as much. So my favorite three would be WIMPs, axions, and primordial black holes. Okay.
So WIMPs, the weakly interacting massive particles, they do have an interaction, which is the weak interaction, the weak force. Okay. And axions, what they do is that they can actually, in the presence of a magnetic field, they turn into photons, into light. So they can switch axion photon, axion photon, and then you can detect that light.
Now, primordial black holes, they would be black holes that formed very early in the history of the universe. They don't evaporate right away? Some of them do, so they have to be bigger than... The smallest ones do, but there would be some left over. And they form wherever there's some region of the universe that has more an excess of stuff in it, an over-density that collapses into a black hole.
And that, for example, could be at some phase transition in the early universe. This is like when water boils, it switches from liquid to gas, and that's where you get these... fluctuations, and boom, you would make primordial black holes. And the reason people care nowadays is because gravitational wave detectors are seeing merging black holes, and some of those could be primordial black holes.
So people got all excited about primordial black holes again. Okay. As far as WIMPs go, you can either define them, you can make it, shake it, or break it. Right on. Go ahead, do your thing. Shake what your mama gave you. Let's talk about the make first. Shake it or break it. Make it, shake it, or break it. So the make it is in particle accelerators, such as the Large Hadron Collider at CERN.
You shoot really rapidly moving protons into each other. moving nearly at the speed of light, and out come potentially dark matter particles like WIMPs. And you look for them that way. No discovery yet, okay? So it would have a signature that you couldn't otherwise identify, and you would ascribe it to dark matter. Yeah. Because you otherwise know what you're supposed to get out of it.
Yeah, if it's ordinary stuff, then you know what to expect. But if you're making some kind of new particles, then they might escape from the detector without, and you'd see that as missing energy. Okay. You'd add up all the energy of all the particles coming out and get there to be some missing energy. Okay, there you go. And do you want to hear about the shake it? Yes. Yeah, yeah. And break it.
I mean, yeah. Now, we've got to make it. You can't leave without shaking it and breaking it. All right. Okay, so the shake it is you've got your detector deep underground, and a particle comes along, hits your detector, gives it a little bit of energy, and you look for that energy deposit. So it's shaking that nucleus. It's like a little vibration. Exactly.
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Chapter 6: What role do primordial black holes play in dark matter research?
Greetings, STEM nerds. Mike from Colorado here. Since the time of Edwin Hubble, we look at distant galaxies and calculate their speed based on the redshift we measure, which we attribute to the Doppler effect. However... We also know that photons lose energy when traveling out of the gravitational field, which also exhibits as a redshift.
Given that dark matter accounts for some 80% of the gravitational universe, how do we know how much redshift is due to the Doppler effect and how much is due to gravitation? Is it possible that the speeds we calculate for distant galaxies are just an upper bound on their actual speeds? Well, there are... On the average, galaxies are moving apart from one another. That's the Hubble expansion.
That causes light between some distant past and us now to stretch. The wavelength of light stretches. However, there's no question when you go, for example, some of that light, if it goes through a galaxy on the way here or goes through a cluster of galaxies, that also changes its wavelength. And in fact, we use that to figure out where a cluster is or what a cluster is doing.
So it's useful information. And we're very aware that you have both effects going on at the same time. So if you're inside our galaxy, like in this room, we're not feeling the expansion. We're not feeling it. I'm feeling it. Yeah, you're feeling it? So this reminds me of what they used to call the tired light model. Okay. The light's just too tired. Right. I done been through a lot, y'all.
I'm telling you, traveling between these galaxies, y'all don't know. This is killing me, man. So tired light. I don't even have masks. I feel so damn heavy. Oh, y'all don't know. Y'all don't know. So tired light would be reddened. Right. Okay? It would be reddened. However, there's also spectral features of elements within the spectrum.
So you could take regular light and it would redden, but if it's the expanding universe and it's Doppler shifted, the lines would shift. Yeah. Yeah. They would shift and it had nothing to do with red or anything. They would just shift. Gotcha. And they shift. They sure do. They sure do. Gotcha. And so you can still have tired light, but you can't blame that redness on the expanding universe.
Very cool. That's a good answer. And if we animate StarTalk, you will be the voice of the photon. Adam had a hard day. Wait, now who's going to be the wimp? What? Oh, and then, of course, before that, there were the machos. The machos. Oh, that's right. Massive compact halo objects. So for a while, we had machos and wimps. Macho and wimp. Yeah, we did. Just so you know, men were naming things.
Yeah, right. And the experiments looking for machos. Ogle. Ogle, yeah. Eros. Ogle, Eros, and macho. Yeah. Okay. OGL, Optical Gravitational Lens Experiment. Okay. Eros, E-R-O-S. What does that stand for? I don't know, the god of love, like Cupid? Yeah, yeah, yeah, yeah. It's the only one I like. What's wrong with Venus? Well, first you're OGL, and that causes Eros. What's that mean?
We got time for one last question, if you can answer it fast. Okay, go. Okay, here we go. This is Brian Whelan. It's a test of you. Brian Whelan says, hello, Dr. Tyson, Freeze, and Lord Nice. Captain Ben from Sag Harbor here, reaching out 30,000, 35,000 feet en route home. Oh, he's actually in the cockpit sending us this message. Oh, because he's captain. He's captain. Wow.
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Chapter 7: How does gravity affect the behavior of dark matter?
Yeah. Well, there. Give me a fish bump on that. All right, all right. We'll take it. This has been another StarTalk Cosmic Queries, a cosmology edition. I'm loving these. Nice. And how many cosmologists we got? We got Jana. We got Brian Green. Oh, Jana Levin, just so you know, was my first graduate student. Whoa! Yeah. Very cool. Look at that. Okay, we have the two Bryans. Yep.
We have Brian Cox and Brian Green. What more do you need? We got Chuck Lew, too. Oh, Chuck Lew, but he's not deep cosmology. He's an extra galactic guy. Extra galactic. Yeah, yeah, yeah. All right. We got enough. Yes, enough, definitely. Anybody else out there, come on. All right, we got to call it quits there. Chuck, always good to have you. Always a pleasure.
Katie, you're going to be a regular from now on. That sounds great. All right. Love it. You got it. Neil deGrasse Tyson, your personal astrophysicist, as always bidding you to keep looking up.