Dark Universe Decoded with Katherine Freese

- Yes.

- The Katie Freeze coming in.

- That's about dark matter, dark energy, big bang. - Rockin'. - Yep, the only cosmologist who sounds like a Batman villain, Katie Freeze. (screaming)

- Coming up on Start Talk. - Welcome to Start Talk. - You're a place in the universe where science and pop culture collide. - Start Talk begins right now.

(upbeat music) - This is Start Talk. - You'll be able to grasp Tyson your personal astrophysicist. This is gonna be a cosmic queries addition

on cosmology to who who who who who who who who who. - There's no end. - A cosmic queries we can do on cosmology. - I suppose there is not. - This is Chuck Nice right here.

- That's right. - Professional comedians stand up comedian. - There is an end to me. (laughing) - So cosmology.

- Yeah. - So we're broadening our stable of cosmologists to whom we can reach out for our queries.

And today we have a second timer.

- That's right. - The one and only. - Katie Freeze. - Katie, what's up? - Yeah.

- Welcome back to Start Talk. - 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. - 'Cause that's cosmology writ large. And we just, we poked your brain about all manner of things.

And this is gonna be a cosmic queries. We have told our Patreon supporters that you're gonna be on. And they're fans of yours. And they've written in or they became fans of yours when they saw your expertise.

And they wrote in and the questions are here. - Well, thanks a lot. I haven't seen these queries. - Well, neither of I. He's the only one who's seen him.

- Yes, so. - So, and I'm the only one who can't answer them. (laughing) - That made me true. - That is kind of fun.

- I don't even can't answer them. - I haven't seen it. - I don't even know who can't answer them. - I 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, I did it to a black hole. - We still don't know the deal. - We still don't know that one.

- Everybody's saying that. - Maybe Teddy knows. - We could find out what was fun though, yeah. - But let me get your bio here. Director of the Weinberg Institute for theoretical physics.

UT Austin. - That's Stevie Wonder, Steven Weinberg. - Yeah, 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. His office was three doors down for me. He recruited me to UT Austin.

“Maybe that's why I think he's the greatest.”

(laughing) - That helps, who gave you the good job, right? - Yeah, yeah. - But he was only named in his death. - 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? - 'Cause he went to my high school.

- Oh, ah, bang. - Oh, Bronx Science. - The Bronx High School of Science. - Yeah, yeah, yeah. - Both he and Shelley Glancho went through

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. - 10 years, thank you, you really,

the Swedish government gave me a $15 million grant

over 10 years to do Cosmo Particle Theory, and that was so much fun. - Wow. - Did you have students, too, and everything? - Oh, I did.

- Was 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. - Yeah.

“- Okay, because I think when we last interviewed you,”

you were like fully up and up and running with them. And what I was, oh, and I'd love this back, now 10 years ago, the Cosmic Cocktail. - Yeah. - Can you get a better title than that?

- Shake it, and I don't dare. - I don't think, three parts dark matter. - Oh, 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. - Wow.

- And that was a book I wrote 10 years ago. So, I guess it was a good one. - Wow. - 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? - Right, because it was folded into your life. - It was. - Yes, very important feature of that.

Thanks for reminding me. It just made it a much more interesting account. - Yeah. - Right, right, cool. - Here's another plug for it.

- Thank you. - Yeah, Amazon ran out again. (laughing) - So, when the chat for a bit before we go to Q&A, catch us up on a couple of things,

these early galaxies that it has discovered in a zone of the early universe. We are not supposed to. - So, wait, you're trying about the James Webb Space Telescope? - Yeah, yeah.

- Yeah, not the administrator of NASA in the 1960s. - Yes. - After whom the telescope was named? - Yes. - You know, he was a accountant?

- James Webb? - I did. - One of the rare, non-scientists after whom a telescope is named. - And a accountant?

“- I think that's what's his main training.”

- That's pretty wild. (laughing) - I guess he was, well, was he important for a NASA? - Well, what was he?

- He was, what was the head of the water taken? (laughing) - While we went to the moon, he was head of NASA. So, it was a, it was a, give it a little back to that. - Look at that.

- In fact, because you need, you need good administrators, not just good scientists. - It may start to happen. - Well, you're a rocker-free.

- Well, you're a rocker-free. Administrator, when they start name and stuff. - Yeah. (laughing) - 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.

And so, let me back up. We're trying to figure out what dark matter is made of. - Yes. - And we think it's some kind of particle we have and identified yet.

- Yes. - And most of the experiments now involve these giant tons and tons of liquid xenon. And so, the idea is, okay, instead of having-- - That's because xenon has some probability

of interacting with the dark matter particle. - Yeah, yeah, dark matter particles flying around in the galaxy. And by the way, there would be billions

going through your body every second.

- Mm-hmm. - Yeah, but it's okay. Only one a month. It's you. - Yeah, I thought I fired for a reason.

- And so, there's a lot of elements on the periodic table. Why do you know that xenon might work when we otherwise know nothing about dark matter? - The way these detectors work is the dark matter comes along.

Hits one of these xenon atoms deflects off of it and the xenon gets some energy deposited in it and they're able to detect that.

“So, you have to have a detector design that works”

and was xenon, we know how to do it. - Okay, so it could be any particle that that would happen to, but xenon has some other convenient properties. - So, the kind of interactions we're looking for

is from the weak force, very, very weakly interacting particles. - Hence the name. - Hence the name, weakly interacting mass particles. And there's people need to build detectors that are, that they know,

you need to know how to build the temperature. I don't know how to answer this one, Neil. - No, so, let's say differently. A neutrino detector, for example, that uses vats of liquid, uses some kind of chlorine molecule

but not xenon. So, where are these xenon detectors? - They're deep underground. - Okay. - One of them is underneath the aponine mountains

outside a Rome, okay? - You know, the aponine mountains on the moon. - Well, I named after those. - I was gonna say, you've actually said that. - Yeah, they came first.

(laughing) - The reason why I know them and reason why they are important is the phase of the moon that's best for telescopic views is half moon. - Okay.

- Because shadows are the longest. And the aponine mountains crosses the half moon divider, the terminator. And so, aponines is pop on a first sighting of the moon. So, to me, the aponine mountains are on the moon.

Not in Italy. - All right, okay. - Well, if you could build something on the moon though,

“even better, because the reason you have to go underground”

is to get away from cosmic rays. - Okay. - Right.

- And there's a million cosmic rays

for every one of these dark matter particles if you're on the surface of the earth. So, we go deep underground, because the cosmic rays don't make it down there. - But the dark matter particle would.

- But the dark matter particles would. - Okay. - Based on what we think dark matter particles would be like. - Well, because they're only weekly interacting. (laughing)

- Normal particles. - Normal particles. - It's a electromagnetic. - Electromagnetically. - If you and I collide, we're not getting very far.

- No, that's right. - We don't pass through each other. - We don't pass through each other. - Right. - I'll tell you something about xenon.

Makes a hell of a headlight. (laughing) - It just wanted to contribute something. I don't know. (laughing)

- We'll talk about here another something about xenon. Does other thing about xenon? It's become very expensive, because the xenon experiments have bought the entire world supply.

- Yeah. - No, I'm serious. - Wow. - I'm serious. - Now you're telling me you should tell me you should.

- Before these experiments started. - We just got it on the cornering of the xenon market. - Oh my God, that's true. (laughing) - Which is why we want a proposal alternative.

So instead of these giant detectors, we're going to dig up little rocks from deep underground, and they've been collecting dark matter tracks for a billion years. We're so we're placing volume with time.

- Wow. - And that cool hands paleo.

- Okay, now that is the first of all,

- Wait, wait, so how do you know which rock to get? - We're any rock. - Oh, well, we had to talk to a lot of geologists. - Uh-huh. - And, you know, this was the first paper

with a few theorists, we're in 2018, and next thing you know. - This was, so in 2018, that was only a proposal. - It was, yeah, we wrote a bunch of theory papers. Not every day does this stuff turn into reality.

I've done a twice now. You know, the underground detectors, our papers got that going, and now with paleo detectors, that's actually becoming a major experimental effort, isn't that cool?

- And it's a cool type name for a detector too. - Yeah, yeah.

“- So they tell you which rocks would best respond to this, right?”

- And the answer is oliveene.

- Oh! - Oliveene. - Oliveene. - I know oliveene. - You do. - Yes.

- Okay. - There's a class of meteorite called palicites. Where? Oh, my gosh. So what do you get a meteorite from?

It's a smashed whatever it used to be. - Right. - So if it's a protoplanet, it partially, as the geologists would say, differentiated, because at some point in its formation,

the heavy stuff would fall to the middle, the lighter stuff would float to the top, okay? - If, however, it cools before it fully segregates, then the metallic inwards can trap oliveene crystals. - Oh wow.

- Within it. - As they were slowly bubbling their way up to the top. And so a slice of these meteorites,

rear lip, if it's thin enough,

the thickness of an oliveene crystal, you see the metallic meteorite and these green crystals are going through. And we have a sample of one in our whole universe. - Oh, they're cool.

- Oh, they're cool. - Oh, I got to see this. - Oh, I'll take you now, right after this. - There you go. - Very cool.

So in other words, it's rare because the boundary layer between the dense middle of a protoplanet and the lighter things that float up is very thin. And so when you smash the whole thing, you have a lot of rocky stuff, less metallic stuff,

and even less at the boundary layer. - Oh, so-- - Well, can we borrow your oliveene to look for dark matter tracks? - I, you gotta know somebody. - Oh, okay.

- You gotta know somebody who works here. (laughing) - I thought I did. (laughing) - Yeah, no, we can totally, we can totally explore them.

They could be the key sitting on around noses. It's been here for 25 years. - Well, then it's been collecting cosmic ray tracks. - Oh, yeah, no, it's we didn't have it. - Sad.

“- Yeah, do you guys have any deep under the earth here?”

Like, is there a signature? - It still has to get through the building. - So we want to know about the sub basements that still have 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. (laughing) All right, so I've congratulations on this

that this is now a burgeoning next step in this.

So why a billion years and not a hundred million

or fifty million doesn't 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.

- That's deep. And then the other idea is if we get rocks from different ages, we are also can study neutrinos, 'cause 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. - Yeah. - And that is because the supernova, that's where the neutrinos come from.

- Oh, I forgot to say that.

“- Yeah, neutrinos give off a lot of supernova.”

- Right. - No. - No, no, supernova give off a lot of neutrinos. And so you, which supernova which you're dying exploding stars.

And you can look for the neutrinos from the supernova. - Right, cool, man. - And neutrinos are, once again, you're weekly interacting.

- Yeah, they are also weekly interacting parties. - Yeah, yeah. - Yeah, yeah. - Most of them fortunate. - No, the other thing we can do is with it.

- Weekly interacting, yes, the parties, yeah, yeah. - Well, we know who named them that. - Oh, who named them, I forgot. - My turner? - Is that right? - Mm-hmm.

- My turner. - So, yeah, I would have made sense if you said I turned. (laughing) - Whoa! - The word of ponemas comes to mind. (laughing)

(upbeat music) - I'm Nicholas Castella, and I'm a proud supporter of StarTalk on Patreon. This is StarTalk, with Neal de Gras Tyson. (upbeat music)

- 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.

if dark energy changes over time.

- The biggest evidence for dark energy changing over time comes from a different experiment, the Dessie experiment. - Okay. - And what they're looking at.

- Lucy and Dessie. (laughing) - Dark matter, you guys have a sprain of your door. - Oh, that's good, that's good. - But Dessie, so other than Lucy and Dessie,

what does Dessie say for astrophysically? - The dark energy spectroscopic instrument. - Okay, that's all right, 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.

Thousands 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. And so as time goes on, you look at how big are those spheres?

And that tells you about the expansion of the universe. - Yes. - And what they're saying is-- - The spheres would grow with the universe. - Yes.

- And so by studying that you can figure out is the expansion, what the expansion is doing is the 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 that the acceleration is slowing down.

- Oh. - Because 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?

- Please. - So my collaborator, Yun-Wang, and I said, 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?

- A different people have different opinions. - A simpler way to look at it where the effect goes away. - Yep. - 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. (laughing) - I mean, that taps, Arkham'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 saying, 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 Arkham's razor, you friend? - Yeah, let me just think, removing all other considerations the simplest answer is the most likely. - That's a modern interpretation, what he actually said was. - That's a head.

- Multiplicity ought not be posited without necessity. - Oh, wow, wow. (laughing) - So Arkham named for William of Arkham, he goes way back. - Okay.

- Yeah. - Like, 700 years. - Wow. - So he had some insights into nature that persist to this day.

William of Arkham. - So enough. - He knows how to turn a phrase, that's for sure. (laughing) - So I'm betting on Katie on this one, definitely.

- Very cool. - So, 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.”

- Yeah. - It is a constant. - Yeah. - If you're a cosmological constant. - Right, if you want to start making that not constant,

then it's no longer Einstein's general theory of relativity is some modification to it. - No, it doesn't, it, it, it, it, it, it. - How do we 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, okay.

We could call it gobbledygok. - I've already made it, dark matter, dark energy or Fred and Wilma. - Okay. - 'Cause it doesn't have any bias at all.

It just, two words. - Well, I don't know because we know dark matter exists but I'm not so sure about dark energy. I want Wilma to exist, but anyway. (laughing)

But so dark energy, there's two, there's two possibilities.

“One is, as you said, you have to modify Einstein's equations.”

- And it 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 equation.

- It should be had a, you had a way to modify Einstein's general theory of relativity. - Well, more specifically, the evolution equation

what I, what I, we had been working in extra dimensions

if you have strength theory. - As one would do, what do you use?

“- As one would do, because it's one does.”

- As one does, so in strength 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, so the equations would be sound within the universe, left to its own devices, but influenced by outside of it, you gotta give it some slack.

- Yeah, you do. You gotta add these other terms into the equations, which describe the evolution of our three-dimensional universe. - She just called our universe at the slice. - I did, yeah.

- I believe that. - I'm kind of an interesting slice, I like it. - 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.

“I don't look, and anyway, I don't even know why I said this,”

let's say it. - But yeah. - But you know what they're called in physics, they're called brains, BRA and E. - Which is what we're remembering.

- Which is what we're remembering. - Which is what we're remembering. - This is what we're remembering. - Yeah, yeah. - Yeah.

- Like thin little dividers. - So the question you're asking to do some other of these brains contain BRA, I ends. - Mm-hmm. - And we don't know.

- 'Cause we know ours does. - Right, I mean. - I think so. (laughing) - We told him to say, he told me to be able to call it that.

(laughing) - We used to turn loosely and argumented. - So on the, 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 in Harvard. - Oh yeah, she's great.

And so she was talking about the warp factor in her theory and I thought they 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 gonna go to Star Trek,

so 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, they weird looking, but they're made of the same-- (laughing) - But they're too, my pets like we are, and their bowl is accelerated expansion

of their evil empire. - Correct, that's right. They're quite draconian and their whole process to take over everything. - Yeah.

- Well, Cardassian. - Yeah, they're the Cardassians. - Yeah, yeah, yeah. - All right, so you got questions from that? - We got, let's get to it.

- Yeah, let's just jump right in. - Okay, okay. - And you haven't seen these questions. - Oh, no, that's not fair. - Why do you know what I mean?

- That's a whole thing here. - All right.

- Well, this first question is from

Anthropocosmic Dylan, who basically says, "Hey, yeah." He says, "How do dark stars work? What would they be like to visit? "And how do they impact extra solar systems

"and potentially astrobiology?" So he says, "Whoa, he wants you to just answer everything." - But it's right off. - Well, let me depend that 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, "but if the star shrinks, the surface gravity goes up. "You'll be a point where the surface gravity prevents "the light from escaping and the star will disappear "from the universe."

- In other words, what we call now black hole? - 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.

- Like star star.

“- I don't think that's what this question is about.”

I think their 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 a dark matter.

They're the first stars at 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. But doesn't so it's ordinary matter powered by dark matter.

- Just one of your early papers. - Instead of by, there's no fusion. It's dark matter power. - Wow, yeah. - That's crazy in the stuff.

- And these things, 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

- They go because they're absorbing dark matter.

“- No, because they're absorbing ordinary matter.”

Normal stars can't keep growing because their surfaces are hot. You know, they have fusion fusions hot. - 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 the huge. - They're huge and they're cool, which means they can keep a creating matter.

Grow, grow, grow, grow. And they get really, really big. - So there's no pressure on the outer surface to prevent new matter from creating to it. - Yeah, exactly.

- Exactly. - 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.

Well, we'll take 'em. - You'll take 'em. - We'll take 'em. - Whoa. - Yeah, I'm excited.

- When you win your Nobel Prize, will you come back and on their show? - Is that a kiss? - No. - No.

- Okay. - Oh, no. - Oh, no. - That was a very, yes. - Very.

- Oh, no, I'm sorry. - No, he's still learning social cues. - Oh, I'm at the opposite. - Oh, there you go. - Yeah.

I'll tell you this, once you write, that is Nobel stuff right there, man. That's fantastic. - So 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 'cause 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.

- So Dark Stars could explain a lot of things that could explain when they died, the super-massive black holes, when you see it 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. - Well, yeah. These are all very bluntly descriptive stuff we've seen the early universe,

'cause 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 red dot. - Now what about the blue monster?

(laughing) - And we had 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, they don't look blue, they look very infrared,

'cause that blue has been red shifted

to the sweet spot of the James Webb telescope. - Yeah, yeah, yeah. - But yeah, that's very cool. - All right. - Okay, well, what a great question,

Anthropode, 'cause she said she's coming back after her Nobel Prize. - Absolutely. - Now, here's the best question. - Can I wear your Nobel Prize when you come back?

(laughing) - So here's the best line related to that. It was from hoop dreams. Do you know the one? - I don't know, I don't know the one.

- You know the one? - You don't know the movie? - I don't think I know hoop dreams. - hoop dream ahead. - Dude, it's a documentary.

- Oh, you don't know hoop dreams. - I do not know hoop dreams. - You're going ahead. - Yeah, it's a documentary. I'm 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 in famous,

will you remember us as one of them goes off? And he says, "If I'm not rich in famous, will you remember me?" - Oh, that's good. - That's good.

That's good. - That's really good. - That's good. - That's good. - That's good.

- That's good. - That's good. - That's good. - That's good. - No.

- And to both. - All right, let's move on. - This is Nate. - Nate says hello, Dr. Tyson, Dr. Freeze, 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 it. This guy, dude. - Thinking. - Yeah, man.

- Nate, bro. - Whoa. - Dude, whoa, so let's start from scratch. - Yeah. - We're calling it dark energy

because that's a place hold to turn. We don't know what the hell it is. 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 gonna say, thanks.

He's not ordinary matter, and it would be dark matter. So all of that stuff clumps together is attracted together. - But energy contains a matter equivalent. - No, no, 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 behaviors. Pushing things apart from work.

“- That's why we should call it just Wilma.”

Something that doesn't have the word energy in it. - Yeah, so it's confusing because matter and energy

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 because it's acceleration.

So it's a completely different type of thing. - Yeah, but that fact, we calculated with that and you're off, by the way. - So 10 to the 120? - Power, yes.

- Yeah, and the exponent, yeah, well, yeah. - Well, I'm not saying we understand. - 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, and it doesn't mean there's nothing. It means particle, anti-particle pairs,

the pop into existence, the last infinitesimal amount of time, and then they disappear again, but that serves as an energy. And it has been measured.

“There's been two plates that are dropped.”

- It's dropped at the Casimir effect. - Yeah, it's 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.

In this point, where there's-- - It's just a track, right? - Yeah, yep, yep, yep, yep, yep, yep. It's the same vacuum, the same exact same thing. - Yeah, 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-- - It's the very wrong answer, yeah, okay. - The one of the deepest unsolved problems in all of physics. - All right.

- Wow. - And it gets worse. - It gets worse. - It gets worse. - People thought, you look, somehow,

somebody will figure out how to bring that number down to zero, and it will 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 this driving acceleration. It's neither the big answer nor is it zero.

It's somewhere in between, what the heck? - Mm, all right. - All right, I'm talking too much. - No, we love it. That's the whole point of why you're on it, yeah.

- Oh, wow. If you're talking a lot, it means I have less to add. So it is, your words and ideas and brilliance are gracing this real expert. (laughing)

- All right, all right. - On some, on some points. - Yeah. (upbeat music) (upbeat music)

All right, let's go to Simeekshana, who says hello Dr. Tyson, Dr. Fries Lord Nice. This is Simeek from Delhi. - I am a new member here. - Nice, okay.

- Thank you. - Welcome. - Well, go ahead, you do it. - Welcome to the universe. - They do.

- You got an official welcome there as to me. - I'm a cosmos voice. - That's right. I want to know where it does the scientific consensus stand on as an alternative hypothesis to dark matter today.

- I don't understand that. - But anyway, I don't understand. - We're supposed to be revision. - I don't mean to. - Interactive, massive particles.

- It's a candidate for the dark matter. - Oh, okay, but it can't be a substitute, but anyways. - No, it is a type of dark matter. - It's a type. - That's the answer.

- That's the answer. - That's the answer. - 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. - 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. - Wimps, the weekly interacting mass of 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.

that it has more an excess of stuff in it

and 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, switches from liquid to gas, and that's where you get these fluctuations

and boom, you might make primordial black holes. And the reason people care nowadays is because gravitational life 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 whimps go, there's, oh, you can either to find them, you can make it, shake it or break it. - Right on.

(laughing) - Do your fan. - Shake, what's your mind going on? - Oh, I learned nothing. Let's talk about the makers. - Make it, make it, make it, make it, make it, break it. So the make it is in particle accelerators, such as the large hat on collider, it's sern, you're shoot, really rapidly moving protons into each other, moving nearly to speed a light and outcome, potentially, dark matter particles like whimps.

“And you look from that way, no discovery yet, okay?”

- So it would have a signature that you couldn't otherwise identify, and you would describe it, to dark matter. - Yeah.

- 'Cause you always 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 that they're seeing it. - All right, right, right, right, all right. - Okay, there you go. - And do you want to hear about the shake it? - Yes, yeah, yeah, yeah. - Yeah, yeah, yeah. - I mean, yeah. - Yeah. - Now we're out of make it, we can't leave without shaking it and breaking it. - Oh, yeah. - Okay, so the shake it is, you've got your detector and 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. - That's just like a little bit of vibration. - It's a little bit, yeah. - Exactly, it's a little bit of vibration. - It's exactly what they're looking for. - Yeah, it's exactly, yeah. - Got you, got you. - Or some light that comes off or whatever, so that's what they're doing. - Okay. - And then the break it is 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, and 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. - That's ice cube. - That's ice cube. - Ice cube. - Yeah, two miles down. - Great. - Great. - The countin' means straight out of South Pole. - Oh, that's good, that's good, that's good, yeah. - 'Cause ice cube was the answer to the countin'. - Yeah, that's good, that's good. - Yeah, that's good. - Yeah, that's good.

- We like that, yeah. - All right. - Yeah, that was great. That was a great question, so mate for your first time asking,

anything here on Star Talk, and what are from Old Delhi from Old Delhi?

“Make it, shake it or break it, just remember that. All right, all right, this is Chris Hampton, he says,”

"Dear Lord Nice" or "Barrant." - Christopher Hampton, that was a playwright, it's a playwright. - Really, okay. - Okay, I'm not familiar with them. - Yes, very nice. - Is it living playwright? - I think so. - Okay, if it could be him, okay. It's just "Dear Lord Nice" or "Barrant." No, actually, you dug Paul Maccurio, "Barrant." So it's just, what's part of the way I found out, they're kind of the same, the titles, which, you know,

we're gonna have to demo Paul. I'm joking, I love him. I'll cook dark energy, be caused by a constant inflow of space time itself, perhaps through black holes from a parent universe, and other words, we're bringing more in than there is flowing out like a Brita flat iron system. - Okay. - Oh, wow, yeah. - 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, and it flows through and then I drink it. But, 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, and people have thought about that. - You know 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, but he said the only way out of this is if the universe”

is infinite, then you can't favor one point to another. - A really Newton said that? - Yes. - Wow. - Yes. - Mark Gye. - Yeah, what's the answer? - You think Dan? - That's why he's in right over there, on my desk. - Did he know the, I was, that's because he didn't know the universe was expanding, right?

- Yeah, it's probably the universe was too weird for everybody. - Yeah, everybody. - Yeah, it's been not liking it. - What did Einstein say,

something about God or playing? - He's always talking about God. - Well, that was quantum mechanics. - Quantum, God-playing dice.

- But he's expanding universe, yeah. - He didn't like the quantum mechanics, he didn't like the expanding universe.

“Is that interesting? - That's why. - Which a lot of this is, these are fields of physics that he started.”

- That he created! - Quantum, from the film of his play. - The stuff that he was playing. - Oh, wow. - The Nobel Prize is given to crumbs that fall off his plate. - Wow. - Oh, what the hell, this is my guy, but what the hell, let's move on to that. - Wow, that's amazing. - That's, that's pretty, well, all right. But when he says a constant inflow of space time, it's self. - No, no. - I don't, 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 wouldn't, would, to me, would include all of that stuff. - God, yeah. - We are living in, within space time, okay? - Okay, okay. - A little uncomfortable with that notion. - Okay, listen, I'll accept that, because we are all living in space time, so, you know, that's pretty simple to accept. - Greetings, STEM nerds. - Yeah. - Mike from, thanks to 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 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. - Right. - However, there's no question when you go, for example, some of the 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 the 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. But because... - I feel it. - And how you're feeling it? So this reminds you of what they used to call the tired light model, the light's just too tired. - Right. - Come through. - I don't even do a light job. I'm telling you, traveling between these galaxies, y'all don't know.

This is so loud. I got a killing me man. - It's a tired light. Because you know, I don't even have mass. I feel so damn heavy. - Oh, y'all don't know, y'all don't know. - So... - Okay, good. - 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, 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 nothing to do with red or anything. They would just shift, and they shift. - Yep, they should do. - They sure do. - Got it. And so you could 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 Star Talk, you will be the voice of the photon. - I don't have a hug. - Wait, now who's gonna be the whimper? Oh, and then, of course,

before that, there were the machos. - The machos. - Oh, that's right. Next, you have compact yellow objects. - Right, that's right. - So for Huawei and machos, you went whimper. - Yeah, we did. - Just show you that men were naming things. - Yeah, right, yeah. - And the experiments, looking for machos. - Ogle. - Ogle here. - Aeros. Ogle eros. And macho. - Yeah, okay.

“- Ogle, optical gravitational lens experiment. - Okay. And eros, E-R-O-S. - What did that say for?”

- I don't know, the god of love, like good. - Yeah, yeah, yeah, yeah, yeah, yeah, yeah. - It's the only one I like.

- What's wrong with me? - Well, first of all, Ogle. And that causes eros. - We're- - We're- - We've got time for one last

question if you can answer it fast. - Okay, go. - Okay, okay, here we go. This is Brian Wheeling. - It's a test of you.

reaching out 30,000, 35,000 feet in route home." Oh, he's- he's actually in the cockpit sending us this mess. - Oh, because he's captain. - He's captain. - Wow. - She should be flying the plane. - Well, no, that's fine. - That's fine. - That's fine. - He's the plane flies itself. - Okay, that's fine. He goes still.

- Yeah, still. - Yeah, this doesn't inspire confidence. - Okay. - That's always saying. - Okay. - All right.

I'd rather you be drinking. - No. - All right. - We're 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 electrometically, but would gravity do something similar, sending this message also on my birthday. Happy birthday, Captain Wheeling. - Captain Wheeling. - Yeah, so they had some overlap with the previous question, but let me tune that a little better. All right, if it interacts weekly,

“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 protegaloxies before ordinary matter could do it. And then ordinary matter falls into a tiny-- - Wait, it's telling me that they're protogalactic dark matter galaxies out there. - There were in the early universe, and then ordinary matter filled in there. But 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. In that cool-- - Wait, wait, okay, yes, it's 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 a dark matter, right? So there's nothing to see. - There's nothing to see. - Well, except-- - No, no, if it doesn't interact, right? Then light just passes through,

render them transparent. - No, because of Einstein's lens and 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. - You see that. - But the galaxy itself,

“or the dark matter thing itself, invisible. - Invisible. - Invisible to you, right?”

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, yes. - Yes. - 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 white rabbit, he's dark matter, he's a black rabbit. - Oh, sorry, okay.

- I just went too far in the face. I went too far to the face. - This is what happened. - Katie, thanks for joining us. - Thank you. - That was fun. - That was fun. - That was fun. - Another great show. - Now, if I remember correctly, you have Kim in the city, so you-- - Oh, my boy, my son. - You're a 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 it to your lease, so I'll be here. - Whoa, all right, whoa. - Yeah. - Okay, we will every time you come back here. - Okay. - You're coming right here. - You're gonna sit right there. - And actually those queries were fun. - See, even though you hadn't heard, we're seen them before. - That's right. - Yeah, okay. - All right, good. - Well, the audience knows you now, so believe me. They got a lot more questions for you.

- Yeah, you guys. - Sounds great. And you guys are so much fun. - Oh, thank you. - Oh, thank you. - Oh, thank you. - Oh, thank you. - Oh, thank you. (laughing)

- Well, there, give me a brief first bump on that. - All right, all right, take it.

- This has been another Star Talk Cosmic Queries, a cosmology edition. I'm loving these. - Nice. - And how many cosmologists we got? We got, we got, we got Janna.

“- Oh, Janna, love and just, you know, was my first graduate student?”

- Whoa. - Whoa. - Yeah. - Very good. - Okay, we have the two Brian's. - Yep. - We have Brian Cox and Brian Green. - Brian Green. - That's, what more do you need? - Yeah. - We got, - Oh, we got Chuck Lutu. - Oh, Charles Lutu, but he's,

I, not, not deep cosmology, right? - Right, that's true. - Yeah, that's true. - Yeah, yeah, yeah, yeah, yeah. - Yeah. - All right, we got enough. - Yeah, so that's different. - Anybody else out there, come on. (laughing)

- All right, we got to call it quits there. Chuck, always good to have you.

- Oh, it was a play. - Katie, you're going to be a regular from now on. - That sounds great. - All right. - Love it. - You got it. Neil deGrasse Tyson, you're a personal astrophysicist, as always bidding you to keep looking up. (upbeat music)