Dark Universe Decoded with Katherine Freese

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21:03Neil 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 splaner to do.

21:51Neil deGrasse Tyson: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. Okay. Clean and simple. Yeah. 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. And what those waves did was leave an imprint that throughout the rest of time, galaxies form in these spheres left over from those waves.

22:37And so as time goes on, you look at how big are those spheres, and that tells you about the expansion of the universe.

22:44Neil deGrasse Tyson:Yes. And what they're saying is... Because spheres would grow with the universe. Yeah. Yes. Yeah, and so by studying that, you can figure out what the expansion is doing. Is it accelerating? What is it doing? And what they claim is that the dark energy, which everybody, the vanilla model, is that it doesn't change in time. But it definitely affects the overall expansion of the universe no matter what. It's causing the acceleration, so we think. And what they're claiming is that the acceleration is slowing down. Oh. So it's a decrease in the dark energy contribution to the universe. So now can I put it in a plug for my own work?

23:21Please. So my collaborator, Yun Wang, and I, we looked at the same data and we looked at it differently with a simpler way of interpreting the data, and we do not find that evidence to be very strong, actually. So I don't think it's happening. Big picture, there's a big debate. Is it real? Is the dark energy changing with time or not? Is it time varying or not? and different people have different opinions at this point.

23:45Neil deGrasse Tyson:If you found a simpler way to look at it where the effect goes away and we were betting on the likelihood of one truth or another, I'm betting with a simpler explanation. Thank you. Well, me too, obviously. I mean, that taps Occam's razor. Well, from the data, we're directly extracting the dark energy density, the amount of dark energy, instead of going through a... A secondary. A secondary thing, which is called the dark energy equation of state. So we're doing it more directly, so that's why I like what we're doing better. So you know about Occam's razor? Let me just think. Removing all other considerations, the simplest answer is the most likely.

24:26Neil deGrasse Tyson:That's a modern interpretation. What he actually said was, multiplicity ought not be posited without necessity. Oh, wow. Damn. So Occam, named for William of Occam, he goes way back. Okay. Yeah, like 700 years. Wow. So he had some insights into nature that persist to this day. William of Ockham. Sure enough. He knows how to turn a phrase, that's for sure. So I'm betting on Katie on this one, definitely. Very cool. But let me exit this before we get to the questions with a related question. Okay. You said the vanilla version of dark energy is that it does not change over time. Yeah. That's how it appears in Einstein's general relativity.

25:11Neil deGrasse Tyson:It is a constant. It's a cosmological constant. Right. If you want to start making that not constant, then it's no longer Einstein's general theory of relativity. It's some modification to it. No, it doesn't. How does he accommodate? How can his formulation of general relativity accommodate a cosmological constant that's not constant? I just want to say about dark energy, It is a complete mystery to all of us. We have no idea what's going on, to be honest. We could call it gobbledygook. I've already named it. Dark matter and dark energy are Fred and Wilma. Okay. Because it doesn't have any bias at all.

25:54Neil deGrasse Tyson:They're just two words. Well, I don't know because we know dark matter exists. I'm not so sure about dark energy. I want Wilma to exist, but anyway. But so dark energy, there's two possibilities. One is, as you said, you have to modify Einstein's equations. And that feels wrong to me. Well, you know, I actually had an idea for how to do that in 2002, but let's not go there. I want to talk about the other way, which is we stick with Einstein's equations. Wait, in 2002 you had a way to modify Einstein's general theory of relativity. Well, more specifically, the evolution equation for the universe, the Friedman equation for the universe.

26:32we had been working in extra dimensions. If you have string theory...

26:37Neil deGrasse Tyson:As one would do. As one would do. As one does. As one does. In string theory, you have to have 10 spatial dimensions instead of the X, Y, Z, the normal ones that we usually work with. And if you do that, it's possible that, well, our universe is a three-dimensional surface in there, and there could be another one, and the stuff in between, which we call the bulk, is pulling on our surface and causing the equations to change. Oh. Interesting. So we posited. Okay, so the equations would be sound within the universe left to its own devices, but influence outside of it, you got to give it some slack.

27:19Yeah, you do. You got to add these other terms into the equations which describe the evolution of our three-dimensional universe.

27:26Neil deGrasse Tyson:She just called our universe a slice. I did, yeah. I believe that. It's kind of an interesting slice. I like it. Yeah. It's a dimensional slice. Yeah. That's a dig if I ever heard one. I don't know. Like, during my ayahuasca trip, I met some beings that told me that there were dimensions alongside of our dimension. Like, more than we could ever know. Dimension, dimension, dimension. And that there were dimensions above and dimensions below. So, anyway, I don't even know why I said this. But, yeah. But you know what they're called in physics? They're called brains. B-R-A-N-E. Okay. Which is short for membrane.

28:06Membrane, yes. It's short for membrane. Yeah, just like, yeah. So they're like thin little dividers. So the question you're asking, do some other of these brains contain B-R-A-I-Ns?

28:17Neil deGrasse Tyson:Mm-hmm. And we don't know. Because we know ours does. Right. I mean. I think so. I was going to say, if you want to call it that. We use the term loosely in our dimension. So can I tell you what I called this theory? What? I called it Cardassian cosmology. And the reason is that Lisa Randall was going on about the warp factor, which I thought— It's another physicist up at Harvard. Oh, yeah, she's great. And so she was talking about the warp factor in her theory, and I thought it came from Star Trek, but actually it's just a relativity term that I had heard called something else. And so I thought, well, I'm going to go to Star Trek.

28:57So I went for the Cardassians. So I called it Cardassian Expansion because everything would be made of ordinary matter, ordinary radiation, ordinary stuff, no weird dark energy, but equations would be different. And so like the Cardassians, they are weird looking, but they're made of the same. But they're two bipeds like we are, and their goal is accelerated expansion of their evil empire. That's right. They're quite draconian, and their whole purpose is to take over everything. Well, Kardashian. Yeah, they're the Kardashians. All right, so you got questions for the guests. We got, let's get to it.

29:34Let's jump right in.

29:35Neil deGrasse Tyson:These are directly for— And you haven't seen these questions. No, that's not fair. Why do you know? I don't know. That's the whole thing here. All right, all right. Well, this first question is from Anthropocosmic Dylan, who basically says, Yeah. He says, how do dark stars work? What would they be like to visit? And how do they impact extrasolar systems and potentially astrobiology? So he wants you to just answer everything. Answer it all, Captain. Let me prepend that. Go ahead. In, was it the 1800s or late 1700s? There was a calculation done by a physicist who said to himself, the gravity on a star is whatever it is.

30:17Neil deGrasse Tyson:but if the star shrinks, the surface gravity goes up. There'll be a point where the surface gravity prevents light from escaping and the star will disappear from the universe. In other words, what we call now black holes. Exactly. So it was like the first attempt at thinking about what we now would call a black hole. But so that technically would be a dark star, but I don't think that's what this question is about. I think they're asking if matter can make planets, can dark matter make planets? No, I mean, I think he's asking about my work on dark stars. Oh! And dark stars are not made of dark matter.

30:51They're the first stars that form, and they would be made of ordinary stuff, ordinary hydrogen, ordinary helium, almost entirely. But they're powered by the dark matter that's inside them. So it's ordinary matter powered by dark matter.

31:04Neil deGrasse Tyson:This is one of your early papers. Instead of by, there's no fusion, it's dark matter power. Wow. Yeah. That's some crazy, innovative stuff. If they exist, these things, I'm so excited because we have candidates for them in the James Webb Space Telescope. I'm so excited. They would start out at about the same mass as the sun, but then they would grow, grow, grow until they become a million times as massive as the sun and a billion times as bright. They grow because they're absorbing dark matter. No, because they're absorbing ordinary matter. Normal stars can't keep growing because their surfaces are hot.

31:38You know, they have fusion. Fusion's hot.

31:39Neil deGrasse Tyson:Right. And then so they blow stuff off. But dark stars are cool. Oh, in radius, they're 10 times the distance between the Earth and the sun. So they're huge. They're huge, and they're cool, which means they can keep accreting matter. They grow, grow, grow, and they get really, really big. So there's no pressure on the outer surface to prevent new matter from accreting to it. Yeah, exactly. Exactly right. Look at that. Yeah, yeah, yeah. So they can get really big, and we have candidates in the James Webb Space Telescope for some of those really early objects that are super bright, and they don't know how to explain them.

32:07Well, we'll take them.

32:08Neil deGrasse Tyson:You'll take them? We'll take them. Whoa. Yeah, I'm excited. When you win your Nobel Prize, will you come back on our show? Was that a kiss off? No! Oh, okay. Did you read the body language? That was a very, very... Oh, no, I'm sorry. No, he's still learning social cues. Oh, I meant the opposite. Oh, okay, cool. Yeah. No. 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 my field is that you can have a great idea. And let me back up. Usually when you have a great idea, you kill it in 10 minutes because it violates some observation.

32:51Occasionally, 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. 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.

33:14Neil deGrasse Tyson:Wow. Yeah. These are all, they're 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? Where'd you get that reference? Blue monster is a really, really, really bright object 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.

33:47That's very cool. All right. Okay. Well, hey, what a great question, Anthropocos. So she says 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?

34:01Neil deGrasse Tyson:So here's the best line related to that. It was from Hoop Dreams. Do you know the line? I don't know. 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 this 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?

34:39Oh, 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. Freeza, 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?

35:21This would imply that it is not influenced by the curvature of space-time in which it causes. This guy did some thinking here. Freaking Nate, bro.

35:33Neil deGrasse Tyson:Whoa. Dude. Whoa. So let's start from scratch. Yeah. We're calling it dark energy because that's a placeholder term. We don't know what the hell it is. Right. But if it's energy at all, then it has a mass equivalent and it should have gravity. So does dark energy have gravity? The definition of matter is that it feels gravitational attraction. So that's true for ordinary matter. That would be you and me and you. I was going to say, thanks. He's not ordinary matter. He's not ordinary matter. And it would be dark matter. So all of that stuff clumps together, is attracted together. And energy contains a matter equivalent.

36:11No, you know, for ordinary matter and energy, that is true. But for dark energy, it is completely different from matter. It is something that's causing a repulsive behavior. It's pushing things apart from one another.

36:23Neil deGrasse Tyson:That's why we should call it just Wilma, something that doesn't have the word energy in it. Yeah, yeah. So it's confusing because matter and energy in the ordinary world are related, but dark matter and dark energy are probably not. Okay, so the foundation of this question is not valid because it's assuming that it's participating in the curvature of space-time. And if it's helping to make it, why isn't it responding to it? Why is it spreading things out rather than pulling things in? Well, I mean, it does fit into Einstein's theory of general relativity. It's just that if you have this vacuum energy, it causes repulsion rather than attraction.

36:59It causes acceleration. So it's a completely different type of behavior.

37:03Neil deGrasse Tyson:Yeah, but we calculated with that and you're off by like... Oh, 10 to the 120? Power, yes. Yeah, in the exponent. Yeah, that's true. Well, I'm not saying we understand it. I'm not saying we can calculate it. That's funny. Isn't that the biggest mismatch between a theory and a calculation ever? Yeah, it's really, it's just unbelievable. Vacuum energy, what does that mean? Well, what it means... By the way, there's vacuum energy in this room that you could measure. There are particle... It doesn't mean there's nothing. I mean, it's particle-antiparticle pairs that pop into existence. They last infinitesimal amount of time, and then they disappear again.

37:40But that serves as an energy. And it has been measured. There's been two plates that are trapped.

37:45Neil deGrasse Tyson:This is not the Casimir effect. Yes, the Casimir effect. It is? It's the Casimir effect, absolutely. This is where two, in a vacuum, two parallel plates, you bring them very, very close together, and there's a point where there's a— They just attract, right? Yep, yep. They just plack. Yep, yep, yep. Yep, it's the same vacuum, exactly the same thing. That's pretty wild. But if you do the mathematical calculation, your answer is too big by 10 to the 120 in the exponent. So if you add up all the contributions from all those particles, it gets the wrong answer, and that's considered one of the biggest...

38:20Neil deGrasse Tyson:It gets the very wrong answer. One of the deepest unsolved problems in all of physics. All right. Wow. But it gets worse. It gets worse. It gets worse. people thought, yeah, look, somehow somebody will figure out how to bring that number down to zero and we'll be good. No. All of a sudden, it looks like there's a small amount left over. Well, it's not that small for our universe, but compared to 10 to the 120, there's dark energy, which means there is some vacuum left over that's driving acceleration. It's neither the big answer nor is a zero. It's somewhere in between. What the heck? Alright.

38:56Neil deGrasse Tyson:I feel like I'm talking too much. No! We love it. That's the whole point of why you're on here. Ooh, wow. If you're talking a lot, it means I have less to add. Oh. So it is, your words and ideas and brilliance are gracing the stage. You're a real expert. All right, all right, all right. On some things. Yep.

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43:10All right, let's go to Sumit Sharma, who says, hello, Dr. Tyson, Dr. Freeze Lord. nice. This is Sumit from Delhi. I am a new member here.

43:19Neil deGrasse Tyson:Nice. Okay. Patreon member. Welcome. Well, go ahead. You do it. Welcome to the universe. There you go. You got an official welcome there, Sumit. In my cosmos voice. That's right. I want to know where does the scientific consensus stand on WIMP as an alternative hypothesis to dark matter today. I don't understand that. But anyway, I don't understand the question. WIMP is the abbreviation. I know, weakly interacting massive particles. It's a candidate for the dark matter. Oh, okay. But it can't be a substitute. But anyway. No, it is a type of dark matter. It's a type, right? That's the answer. That's the answer.

43:51It's a type of dark matter. Also, 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. 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.

44:35Okay. 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.

44:54Neil deGrasse Tyson: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.

45:38So people got all excited about primordial black holes again. Okay. As far as wimps go, there's, oh, you can either, to find them, you can make it, shake it, or break it. Right on. Go ahead, do your thing. Shake what your mama gave me. 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?

46:19Neil deGrasse Tyson: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, right? 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 there'd be some missing energy. All right. Right on. Okay. There you go. And do you want to hear about the shake it? Yes. Yeah, yeah. And break it. I mean, yeah.

46:53Now, we've got to make it. You can't leave without shaking it and breaking it.

46:59All right. Okay, so the shake it is you've got your detector deep underground, and the 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. In some cases, that's exactly what they're looking for in some cases. Gotcha, gotcha. Or some light that comes off or whatever. So that's what they're doing. Okay. And then the break it, that's called indirect detection, and that's when, well, dark matter particles, these WIMPs can be their own antimatter, and that means when they hit each other, they annihilate and turn into something else.

47:38And what you got to do is measure that something else. So people are looking for neutrinos, you know where those detectors are? Underneath the ice at the South Pole.

47:48Neil deGrasse Tyson:That's Ice Cube. That's Ice Cube. Ice Cube. Yep, two miles down. Straight out of Compton. I mean, straight out of South Pole. Oh, that's good. That's good. That's good. Yeah. Because Ice Cube was in Straight Outta Compton. Yes, he was. The actor, yeah. Yeah, yeah, that's good. The rapper. We like that, yeah. All right. Yeah, that was great. What a great question, Sue Mead, for your first time asking anything here on StarTalk. From Old Deli. From Old Deli. Make it, shake it, or break it. Just remember that. All right. All right, this is Chris Hampton. He says, Dear Lord Nice or Baron. Wait a minute.

48:22Christopher Hampton, that was a playwright. Oh. Is a playwright. Really? Okay. I'm not familiar with him.

48:28Neil deGrasse Tyson:Yes. Oh, very cool. Is it a living playwright? I think so. Okay. So it could be him. Mm-hmm. Okay. Treat him nice. There you go. He says, Dear Lord Nice or Baron. No, actually, you dubbed Paul Mercurial Baron. So it's just, which by the way, I found out they're kind of the same, the titles, which, you know, we're going to have to demote Paul. I'm joking. I love him. Could dark energy be caused by a constant inflow of space-time itself, perhaps through black holes from a parent universe? In other words, we're bringing more in than there is flowing out like a Brita flat iron system. Oh, wow. Yeah.

49:11I'm not sure how to answer that one. Brita flat iron system. Yeah, what the heck is that? I don't know what a Brita flat iron system is. I have a Brita at home. I put water in it. Yeah. and it flows through, and then I drink it. You know what Einstein had to do to get a static universe? He had to have material somehow bubbling into our universe and appearing out of nowhere on a regular basis. So that is not an insane idea. People have thought about that.

49:35Neil deGrasse Tyson:He knew what Isaac Newton's solution to that was. Go ahead. It was if the universe were just finite, then all the galaxies would collapse to each other. Okay. Okay? He didn't think of the universe as expanding. Right. But he said the only way out of this is if the universe is infinite. Infinite, right. Then you can't favor one point or another. Oh, really? Newton said that? Yes. Wow. Yes. Smart guy. You think? Damn. That's why he's sitting right over there on my desk. Did he know the universe? That's because he didn't know the universe was expanding, right? No, no, no. No, no. That was 1929 that they figured that out.

50:10Expanding universe. Einstein did not like it. Yeah, expanding universe was too weird for everybody. For everybody. Yeah, he did not like it. What did Einstein say? Something about God or playing? He's always talking about God. That was quantum mechanics. That was quantum, God playing dice. But the expanding universe, yeah. He didn't like the quantum mechanics. He didn't like the expanding universe. Isn't that interesting? That's wild. Which a lot of this is, these are fields of physics that he started. That he created. Crumbs that fell off his plate. From the stuff that he was just like.

50:38Neil deGrasse Tyson:The Nobel Prize is given to crumbs that fell off his plate. Well, I don't know what the hell this is, but whatever. Let's move on. That's him. Wow, that's amazing. It is, yeah. That's pretty well. All right. But when he says a constant inflow of space-time itself. No. No. That doesn't make any sense to me, so I'm going to just say no. So space-time can't come from another brain. Right. Space-time, to me, wouldn't include all of that stuff. Gotcha. We're all living within space-time. Okay, okay. So I'm a little uncomfortable with that notion. Okay. Listen, I'll accept that because we are all living in space time.

51:16So, you know, that's pretty simple to accept. Greetings, STEM nerds. Hey! Mike from Colorado. Thanks for the compliment. Yeah, there you go, buddy. 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 gravitation in the universe. How do we know how much redshift is due to the Doppler effect and how much is due to gravitation?

51:50Is 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. Right. 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.

52:34So 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?

52:54Neil deGrasse Tyson:So this reminds me of what they used to call the tired light model. The light's just too tired. Right. Come through. I've been through a lot, y 'all. I'm telling you, traveling between these galaxies, y 'all don't know. Oh, this is killing me, man. It's killing me. Tired light. I don't even have mass. I feel so damn heavy. Oh, y 'all don't know. Y 'all don't know. Okay. 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.

53:47Yeah, yeah.

53:48Neil deGrasse Tyson:They would shift and 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 photons.

54:13I done had a hard day. Wait, now who's going to be the wimp?

54:20Oh, and then, of course, before that, there were the machos.

54:22Neil deGrasse Tyson: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 show you that men were naming things. Yeah, right. And the experiments looking for machos. Ogle. Ogle, yeah. Eros. Ogle, Eros, and Macha. Yeah. Okay. Ogle. Optical Gravitational Lens Experiment. Okay. And. Eros. E-R-O-S. What did that stand for? I don't know. The God of Love, like Cupid. Yeah, yeah, yeah, yeah, yeah. It's the only one I like. What's wrong with Venus? Well, first you ogle, and that causes Eros.

55:05Neil deGrasse Tyson: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 view. Brian Whelan says, hello, Dr. Tyson, Freeze, and Lord Nice. Captain Ben from Sag Harbor here reaching out 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. Should you be flying a plane? Well, no, at 35 ,000 feet, the plane flies itself. Okay, I guess so. He's got time. He goes, Still. Yeah, still. This doesn't inspire confidence, okay? That's all we're saying. Okay, okay. I'd rather you be drinking.

55:44No, stop. All right. Drink it, but still paying attention. Exactly. He says, Listen, I've been wondering, does dark matter coalesce and condense similarly to regular matter? And if not, why not? It doesn't interact electromagnetically, but would gravity do something similar? sending this message also on my birthday. Happy birthday, Captain Whelan. Captain Whelan. Yes.

56:07Neil deGrasse Tyson:So that has some overlap with the previous question, but let me tune that a little better. All right. If it interacts weakly, that's still an interaction. So why doesn't it just make weak planets instead of regular planets? Well, I'm going to answer, I'm going to say something else first, which is that without dark matter, we wouldn't exist. It had to collapse and clump and make proto-galaxies before ordinary matter could do it. And then ordinary matter falls into those things. Wait, you're telling me that there are proto-galactic dark matter galaxies out there? There were in the early universe, and then ordinary matter fell in there.

56:43But is it possible there are some purely dark galaxies that don't have any stars in them? Yes, and people are looking for that for sure. Wow. Isn't that cool?

56:52Neil deGrasse Tyson:Wait, wait, wait. Okay, yes. Very cool. Very cool. So it wouldn't so much be dark, Because that would imply it absorbed light, but they don't interact with light. They would just be invisible. Well made of dark matter, right. So there's nothing to see. There's nothing to see. Well, except that... No, no, no. If it doesn't interact with light, then light just passes through, rendering them transparent. No, because of Einstein's lensing, gravitational lensing. Oh, you see the lensing effects. You see distant galaxies, the light from behind the dark galaxies will get bent. Okay, so it gets bent. So you see that.

57:28Neil deGrasse Tyson:But the galaxy itself, or the dark matter thing itself, would be invisible to you. You could just walk through it and you wouldn't even know. Yes. Ooh. That's cool. There's some serious science fiction material there. There is. Interesting. I love it. Chuck, have you met my dark matter friend? Oh, well, he looks like a black rabbit. What's a black rabbit? Harvey the rabbit. There you go. Harvey was a white rabbit. He's dark matter. He's a black rabbit. Oh, sorry. I just went too far too fast. I went too far too fast. This is what happens. Well, Katie, thanks for joining us again. Thank you. That was fun.

58:05That was good.

58:06Neil deGrasse Tyson:That was really fun. Another great show. Now, if I remember correctly, you have kin in the city. My boy, my son. Your son. So you get through town every now and then. I do, all the time. We will nab you 100 % of the time. I have a rent-stabilized apartment. I just signed a two-year lease, so I'll be here. Whoa. All right. Whoa. Yeah. Okay. We will, every time you come back here, Okay, you're on. You're going to sit right there. And actually, those queries were fun. See? Even though you hadn't heard or seen them before. That's right. Yeah, okay. We're good. All right, good. Well, the audience knows you now, so believe me, they got a lot more questions for you.

58:39You got it. Sounds great. And you guys are so much fun. Oh, well, thank you. Yeah.

58:50Neil deGrasse Tyson:Well, there. Give me a fist 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? Yeah. We got... Oh, we got Chuck Lew, too. Oh, Charles Lew, but he's not deep cosmology. Right. He's an extra galactic. Yeah, yeah, yeah. All right. We got enough. Yes, enough, definitely.

59:28Anybody else out there, come on.

59:32Neil deGrasse Tyson: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.

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1:00:35Neil deGrasse Tyson:Eczema is unpredictable, but you can flare less with EpGliss, a once-monthly treatment for moderate to severe eczema. After an initial four-month or longer dosing phase, about four in ten people taking EpGliss achieved itch relief and clear or almost clear skin at 16 weeks. And most of those people maintain skin that's still more clear at one year with monthly dosing.

1:01:20if you have new or worsening eye problems. You should not receive a live vaccine when treated with EPCLIS. Before starting EPCLIS, tell your doctor if you have a parasitic infection.

1:01:28Neil deGrasse Tyson:Ask your doctor about EPCLIS and visit ebclus.lily.com or call 1-800-LILY-RX or 1-800-545-5979.