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Speaker 1: Hey, Jorge, is it still true that you get a

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Speaker 1: lot of your work done late at night? Yeah? Yeah,

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Speaker 1: you know, it's a little quieter. Nobody's calling you, nobody's

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Speaker 1: bothering you. It's a little easier to, you know, get

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Speaker 1: your thoughts in order. So like you do your best

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Speaker 1: thinking when it's dark outside. Yes, that's right, it's like

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Speaker 1: I have dark energy. Oh my gosh, I think you

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Speaker 1: might have just cracked the mystery. Yeah, what do you mean?

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Speaker 1: Maybe that's what's causing the universe to accelerate outwards. Cartoonists

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Speaker 1: staying up too late? Oh, man, I think you're right.

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Speaker 1: The universe just can't handle so many cartoons, so it

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Speaker 1: has to grow to fit them all in. You are

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Speaker 1: literally blowing it up. Those are some dark thoughts, man,

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Speaker 1: I'll have to stay up late thinking about it. I

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Speaker 1: am more handmade. Cartoonists and the co author frequently ask

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Speaker 1: questions about the universe. Hi, I'm Daniel. I'm a particle

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Speaker 1: physicist and a professor at U c Irvine, and I

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Speaker 1: always thought of the two of us, I was more

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Speaker 1: likely to blow up the universe. Well, you know, I

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Speaker 1: blow people's mind. You blow up the physical universe. What

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Speaker 1: can I say, it's a team effort. Together, we are

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Speaker 1: unstoppable and potentially dangerous, also one of us more so

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Speaker 1: than the other. And now we are here to blow

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Speaker 1: your minds. Welcome to our podcast Daniel and Jorge Explain

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Speaker 1: the Universe, a production of I Heart Radio, in which

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Speaker 1: we do try to blow up the entire universe, but

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Speaker 1: not to destroy it and make it unlivable, but so

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Speaker 1: that we can zoom in and understand it in detail.

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Speaker 1: We want to expand the whole universe as we expand

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Speaker 1: your mind, so we can stretch it in and see

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Speaker 1: right through it. We can mix our metaphors and we

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Speaker 1: can pull things apart as we try to explain all

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Speaker 1: of the craziness and the incredible universe to you. That's right,

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Speaker 1: We try to explode your understanding of the cost moods

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Speaker 1: because it is a pretty big and wonderful universe, and

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Speaker 1: it's also getting bigger. It's getting bigger every year, and

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Speaker 1: it's getting bigger faster every year, which means the size

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Speaker 1: of the mystery, the scale of our ignorance is getting

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Speaker 1: larger and larger every year. Literally, there is more stuff

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Speaker 1: we don't know this year than last year. Yeah, because

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Speaker 1: there is literally more universe today than there was yesterday,

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Speaker 1: and tomorrow there's going to be even more universe, which

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Speaker 1: means that maybe we'll never get to understand all of it. Daniel,

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Speaker 1: Can we keep up with such an expanding universe? We

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Speaker 1: can't think faster than the speed of light, But the

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Speaker 1: universe is expanding faster than the speed of light, which

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Speaker 1: I guess makes it hopeless, doesn't it? Why are we

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Speaker 1: even doing this podcast? That's right, just give up, Daniel.

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Speaker 1: You should become a cartoonist. Is that what giving up means?

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Speaker 1: Giving up? Right? You're you know, upgrading. That's right. Stepping

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Speaker 1: up to being a cartoon is stepping up, upgrading? Yes,

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Speaker 1: that's what you meant to say. No, I think that

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Speaker 1: even though it's unlikely we will ever understand everything about

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Speaker 1: the universe, it's really all about the friends we make

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Speaker 1: along the way, meaning the ideas that we captured, those

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Speaker 1: bits of knowledge that we do manage to extract from

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Speaker 1: the universe and digest, those moments when we pull back

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Speaker 1: a layer of reality and say, oh my gosh, the

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Speaker 1: universe is different from what we imagined. And one of

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Speaker 1: the greatest of those moments is when we discovered that

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Speaker 1: the universe was expanding, and that expansion was accelerating. Yep,

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Speaker 1: the universe is just getting started. Apparently it's getting bigger,

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Speaker 1: faster and faster each year. But do you think Daniel dead?

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Speaker 1: You know, once you figure out the loss of the universe,

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Speaker 1: you don't need to see all of the universe. You know,

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Speaker 1: it's like you you once you figure out the basic rules,

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Speaker 1: it's like you know, and they're done that. That's gonna

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Speaker 1: be the title of my next paper. Actually it's called

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Speaker 1: you know, They're done that. They're done that. Um No,

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Speaker 1: Actually that's the name of a cafe my wife wants open.

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Speaker 1: Being there done that. Oh nice. She's also upgrading tour

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Speaker 1: from a biologist. She's in favor of everything being related.

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Speaker 1: For black beans for dinner, coffee beans with breakfast, chocolate

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Speaker 1: beans for dessert. It's a whole being themed, you know,

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Speaker 1: being there, done that. But I think that there's never

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Speaker 1: a time when we will not learn from seeing more

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Speaker 1: of the universe. And the history of physics is saying, oh,

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Speaker 1: we think we figured out how things work from the

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Speaker 1: studies of this local neighborhood, and then we generalize me extrapoling,

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Speaker 1: and we say, well, the rest of the universe probably

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Speaker 1: works that way, and every time we go to check

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Speaker 1: we find a surprise waiting for us. It turns out

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Speaker 1: that what we learned was a special case because we

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Speaker 1: were looking at only certain circumstances, only when things were

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Speaker 1: really slow, or when things were really cold, or when

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Speaker 1: things were really big. And every time we do turn

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Speaker 1: over that stone and look at some part of the

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Speaker 1: universe we've never seen before, we always do learn something new.

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Speaker 1: So I think there'll never be a time when we

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Speaker 1: say we're done looking around. Well. I think that's good

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Speaker 1: news for this podcast, because that means we'll that we're

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Speaker 1: run out of things to talk about. The stable gigsodes

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Speaker 1: almost and going strong. In fact, it's it's accelerating. I

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Speaker 1: feel like they're accelerating here, derated, which we're making a

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Speaker 1: podcast episodes. Man, we should be doing ten a week

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Speaker 1: at this point. But it is an expanding universe. It's

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Speaker 1: getting bigger each year, and it's getting bigger at a

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Speaker 1: faster rate each time. And it's all because of dark energy,

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Speaker 1: that mysterious energy that's through's force. It's expanding space itself.

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Speaker 1: It's not just making more room, it's growing room in

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Speaker 1: the universe. That's right. Dark energy is the name we

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Speaker 1: give to the observation that the universe is expanding, and

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Speaker 1: that that expansion is somehow accelerating. The key there is

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Speaker 1: the somehow. We call it dark energy because dark means

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Speaker 1: we are cluelest. We don't understand what's going on. We

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Speaker 1: don't even have a good idea for what could be

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Speaker 1: doing it. We just have the observation that is happening

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Speaker 1: and energy because it takes about two thirds of all

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Speaker 1: the energy in the universe to make this happen. So

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Speaker 1: dark energy is a good description for what's going on

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Speaker 1: because it's also basically everything we know about it. I

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Speaker 1: thought it was called dark energy because it doesn't like

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Speaker 1: give off light like it we can't see it like

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Speaker 1: we know it's there because we can see the universe

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Speaker 1: expanding faster and faster, but we like it doesn't like

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Speaker 1: give off a glow or doesn't like make sparkles. It

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Speaker 1: doesn't you know, look like anything. That's what you call

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Speaker 1: it dark, not because we're in the dark about it.

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Speaker 1: It would be cool if it made sparkles. I think

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Speaker 1: if a cartoonist head designed the universe, there would be

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Speaker 1: sparkles or like, you know, action lines or something to

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Speaker 1: show the universe is stretching. Right, every time you have

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Speaker 1: motion in a cartoon, there's always some visual guide there

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Speaker 1: to tip you off. Are you saying that cartoonists should

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Speaker 1: be God's Is that what you're saying. I'm saying it's

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Speaker 1: pretty clear that God is not a cartoonist. You know,

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Speaker 1: conclude from that what you will. Well, maybe God needs

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Speaker 1: to upgrade, just like you know, to everyone else. Step

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Speaker 1: up there, dude, Yeah, grab a pencil, add some sparkles.

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Speaker 1: You know, if the universe is a simulation and the

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Speaker 1: engineers listen to our podcast, or if you're in the

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Speaker 1: believer of a deity whoever is in charge this universe,

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Speaker 1: I hope they do listen to our podcast so that

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Speaker 1: they hear about all the questions that we have. But

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Speaker 1: that is a name we've given it, the the expansion,

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Speaker 1: the accelerating expansion of the universe, dark energy. But and

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Speaker 1: it explains why the universe is it growing bigger and

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Speaker 1: bigger each year. But it doesn't quite explain how we

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Speaker 1: got here, right, You're right, it doesn't explain how we

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Speaker 1: got here. Number one, because we don't even really have

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Speaker 1: an explanation for how it works. Right, Like, we can

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Speaker 1: add some energy to general relativity, and we can use

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Speaker 1: that to expand the universe in our models and to

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Speaker 1: accelerate that expansion. We can do that, but you know,

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Speaker 1: we don't understand where that energy comes from. We have

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Speaker 1: like no description of what that means and where it

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Speaker 1: comes from and how it works and what its future is.

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Speaker 1: And also recently we've discovered that even that picture, that

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Speaker 1: simplistic picture that like maybe we just add a number

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Speaker 1: to Einstein's theory of general relativity, that also doesn't quite work.

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Speaker 1: It doesn't really match the story we see out there

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Speaker 1: in the acceleration of the universe. This is growing problem

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Speaker 1: with our understanding of how fast the universe is accelerating. Right.

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Speaker 1: It's sort of related to the idea that the universe

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Speaker 1: is maybe bigger than it should be, even with this

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Speaker 1: idea of dark energy put into it. Yeah, like maybe

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Speaker 1: the universe is bigger than it should be, or that

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Speaker 1: it's not as old as we think it is. All

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Speaker 1: these ideas are connected because our whole idea of how

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Speaker 1: old the universe is and how vast it is, how

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Speaker 1: big the portion of what we can see is depends

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Speaker 1: on understanding how quickly it's been expanding. Understand how old

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Speaker 1: it is. We unwind this picture, we run the clock

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Speaker 1: backwards and see how long does it take to get

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Speaker 1: back to the Big Bang singularity. So if our understanding

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Speaker 1: of the expansion rate is wrong, that our understanding of

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Speaker 1: the whole history of the universe, including its age, could

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Speaker 1: be wrong. Yeah, it's a big mystery, which we'll talk

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Speaker 1: about later. But there is sort of a concept that

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Speaker 1: might explain all of this, and it has a very

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Speaker 1: imaginative name. Right. Well, I was wondering, you know what

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Speaker 1: a cartoonist called this idea. Well, we wouldn't call it anything.

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Speaker 1: We just draw it. Right what it could be called

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Speaker 1: sparkly dark energy. Everything should be sparkly sequence dark energy.

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Speaker 1: But there is a concept that might explain the expansion

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Speaker 1: of the universe in the beginning. And so today on

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Speaker 1: the program, we'll be tackling the question what is early

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Speaker 1: dark energy? Wait, that's the name, Like, that's the whole concept.

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Speaker 1: Just put the word early in front of dark energy.

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Speaker 1: That is the whole concept. And you know it's not

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Speaker 1: just inspired by cartoonists staying up so late at night

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Speaker 1: that it actually becomes early in the morning. I was

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Speaker 1: gonna say, I'm more of a fan of late dark energy.

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Speaker 1: So when I got an email from you at five am,

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Speaker 1: is that when you're staying up super duper late, it

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Speaker 1: doesn't cross over into early. It means I scheduled my emails.

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Speaker 1: You noticed my emails always coming at five am? Exactly?

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Speaker 1: Why would you schedule them for five am? That's still

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Speaker 1: a bonkers time to send an email. Why don't you

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Speaker 1: schedule them for eight am? Or is that for eight

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Speaker 1: am on the East coast or something? You just got it, Yeah,

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Speaker 1: eight am in an Eastern time, all right? But the

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Speaker 1: question still stands, how late do you have to stay

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Speaker 1: up before you count it as early or are you

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Speaker 1: saying that no matter how late you stay up, if

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Speaker 1: you're still up, it's still late from the day before. Boy,

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Speaker 1: these big questions about the universe are just too confusing.

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Speaker 1: I'm not sure we have a whole episode here to

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Speaker 1: talk about my sleeping habits. I'm sure Aristotle had something

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Speaker 1: to say on this deep philosophical question, But that is

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Speaker 1: the concept that we're going to be talking about here today,

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Speaker 1: this idea of early dark energy. And does that mean, Daniel,

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Speaker 1: there's late dark energy. Late dark energy is the dark

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Speaker 1: energy we have right now that we look around and

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Speaker 1: we see because we are in late times of the universe.

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Speaker 1: That doesn't mean that we think the universe is about

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Speaker 1: to expire or at the end of its life. It

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Speaker 1: just means like recent times of people talk about the

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Speaker 1: early universe meaning the very beginning, and the late universe

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Speaker 1: meaning right now. I see. So maybe we should be

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Speaker 1: it should be called a current dark energy or something

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Speaker 1: that's right. But one of the mysteries is how the

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Speaker 1: universe accelerated in the very early days. Their disagreement about

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Speaker 1: how quickly was accelerating in the very first few moments

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Speaker 1: and how quickly it's accelerating now. And to solve those problems,

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Speaker 1: people are working on ideas to change how quickly the

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Speaker 1: universe was accelerating early on, I see, And will late

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Speaker 1: dark energy at some point become early dark energy only

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Speaker 1: when you go to bed right only Easter standard time.

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Speaker 1: We should call it scheduled dark energy. Right there, you

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Speaker 1: go just in time dark energy. But this is a

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Speaker 1: new concept, early dark energy, one that physicists are thinking

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Speaker 1: about and talking about, and so as usual, we were

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Speaker 1: wondering how many people out there had heard of this

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Speaker 1: idea of early dark energy. So Daniel went out there

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Speaker 1: once again to ask people this question, and I'm eternally

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Speaker 1: grateful to our cadre of volunteers to answer these questions

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Speaker 1: for us so that we can get a sense for

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Speaker 1: what people know and what people are thinking about. If

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Speaker 1: you'd like to participate, please don't be shy right to us.

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Speaker 1: Two questions at Daniel and Jorge dot com. So think

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Speaker 1: about it for a second. What do you think early

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Speaker 1: dark energy means? What does it do? Here's what people

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Speaker 1: had to say. I am not certain, however, I guess

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Speaker 1: that it is similar to the background radiation and that

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Speaker 1: that it's sort of residue from the initial dark energy

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Speaker 1: or the dark energy that initially expanded the universe. I mean,

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Speaker 1: dark energy is probably what's responsible for expanding the universe

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Speaker 1: and accelerating the expansion. I don't know what early in

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Speaker 1: that context means. Was dark energy different in the early

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Speaker 1: state of the universe. I don't know. Um well, as

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Speaker 1: far as they know, dark energy has been increasing since

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Speaker 1: the beginning of the universe. Maybe this is the dark

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Speaker 1: energy that was still around, that was around at the

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Speaker 1: very beginning that we might be able to find if

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Speaker 1: we look far enough back with gravity or something. Probably

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Speaker 1: dark energy is the dark energy from the original Big

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Speaker 1: Bang or soon thereafter that it's all around today early

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Speaker 1: dark energy. I have no idea what it actually is.

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Speaker 1: I'm assuming it's the early stuff that comes to the

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Speaker 1: party early, like maybe in the early part of the universe,

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Speaker 1: kind of like the cosmic micrtive background. Definitely not my wife,

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Speaker 1: that would be the late dark energy. I'm going to

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Speaker 1: take a guess that early dark energy is essentially the

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Speaker 1: same thing as dark energy now, just earlier in our universe,

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Speaker 1: before it was the more dominant of the two between

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Speaker 1: it and gravity. Well, I can think a guess that

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Speaker 1: it's the dark energy right before the Is that just

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Speaker 1: another word for inflation? All right, it's a pretty um

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Speaker 1: straightforward I feel like everyone you said, it's it's dark energy,

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Speaker 1: but early, except it's not my wife. She's late dark energy.

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Speaker 1: That's my favorite answer. Wait, what was that answer from you?

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Speaker 1: Because I know you're wife's days of late also working, right,

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Speaker 1: that's true. Yes, she is on joge time, that's right,

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Speaker 1: or a standard time. She needs to step up and

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Speaker 1: become a cartoonist. Yeah, she's just she's just a pencil sketch. Away,

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Speaker 1: but most people seem to be related to the early university.

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Speaker 1: I guess you know, most people associate dark energy with

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Speaker 1: you know, the universe itself and early I guess you know,

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Speaker 1: you might think that it's dark energy that was there

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Speaker 1: at the beginning of the universe. And it's confusing also

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Speaker 1: because we know that there are multiple periods of expansion

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Speaker 1: in our history of the universe. Like we talked about

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Speaker 1: dark energy, which has been dominating the expansion of the

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Speaker 1: universe for the last five billion years, although it's been around,

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Speaker 1: is part of the mix since the very beginning, it's

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Speaker 1: just sort of only taken over in the last five

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Speaker 1: billion years. But we've also talked many times on the

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Speaker 1: podcast about inflation, which is another period of rapid expansion

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Speaker 1: in the universe in the first ten to the minus

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Speaker 1: thirty seconds of the history of the universe. And as

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Speaker 1: we said several times, we don't know if those are

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Speaker 1: connect that are those different mechanisms for rapid expansion of

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Speaker 1: the universe. Are they related somehow? We don't know, And

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Speaker 1: so it's fair to try to lump these periods of

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Speaker 1: expansion together and say, like, oh, maybe early dark energy,

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Speaker 1: just inflation. That makes a lot of sense. It's kind

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Speaker 1: of weird to think that the universe had basically growth spurts,

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Speaker 1: right like you might think that a cold, random universe

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Speaker 1: which is grow at a steady rate. But somehow the

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Speaker 1: universe has had these like periods of expansion and slowing

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Speaker 1: down too. And one of the key things to understand

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Speaker 1: is that as the universe expands, the mixture that it

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Speaker 1: has of matter and radiation and dark energy, that mixture

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Speaker 1: changes as it expands, because, for example, as the universe expands,

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Speaker 1: matter gets dilute. You have a certain number of particles

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Speaker 1: in a box, and you make that box bigger than

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Speaker 1: the density goes down. But that dilution is different for

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Speaker 1: matter than it is for radiation, for example light. If

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Speaker 1: you expand the box and stretch the space, light also

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Speaker 1: loses energy because it gets red shifted. So radiation gets

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Speaker 1: diluted more quickly, whereas dark energy doesn't get diluted at all.

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Speaker 1: As you make more space and expand the box, you

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Speaker 1: have the same amount of dark energy per unit space,

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Speaker 1: and so the dark energy fraction of the whole universe

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Speaker 1: goes up. So as the universe expands, these fractions change,

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Speaker 1: and then that changes how the universe responds, and so

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Speaker 1: it's this very dynamical system. Right, it's not just like

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Speaker 1: the steady state thing hanging out because it's expanding. That

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Speaker 1: expansion then changes how it expands. Yeah, that's wild. And

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Speaker 1: it's well to think that the universe has things that

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Speaker 1: it you know, conserves and keeps the same, and there's

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Speaker 1: has things that keep growing, you know what I mean,

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Speaker 1: Like matter seems to be constant and it's not increasing,

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Speaker 1: but space needs to be, you know, growing out of

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Speaker 1: the woodwork. Yeah, it's growing out of the universe work exactly.

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Speaker 1: And as the universe expands, dark energy takes over and

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Speaker 1: it makes it expand faster. And that's the source of

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Speaker 1: this acceleration, which is crazy because it suggests the future

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Speaker 1: is all dark energy dominated. Once dark energy is sort

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Speaker 1: of in charge, it basically never let's go as far

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Speaker 1: as we understand. And so it might be that the

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Speaker 1: periods of the universe where matter we're in charge, or

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Speaker 1: radiation were in charge, we're just like the first blips,

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Speaker 1: you know, the first few moments of like a trillion

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Speaker 1: year history. Right, the future is all cartoonists. You should

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Speaker 1: join us now. It is inevitable, I see before it

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Speaker 1: gets cool right as the universe gets colder and colder.

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Speaker 1: But anyways, this idea of early dark energy is really interesting,

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Speaker 1: and so let's break it down for people who are

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Speaker 1: not familiar with this concept of even dark energy. So, Daniel,

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Speaker 1: what is the regular dark energy? So the regular dark

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Speaker 1: energy is a name we give to something shocking that

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Speaker 1: we discovered about twenty years ago. Now, remember that, like

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Speaker 1: only a hundred years ago, we discovered that there are

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Speaker 1: other galaxies out there in the universe and that they

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Speaker 1: are moving away from us, that the universe is expanding.

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Speaker 1: This was sort of a big deal when it was

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Speaker 1: discovered in like, you know, Einstein's universe that he imagined

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Speaker 1: in general relativity was a static universe, no expansion, no acceleration.

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Speaker 1: So the Hubble discovered that, oh, the universe is expanding.

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Speaker 1: Things are floating out there. But people thought, okay, well,

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Speaker 1: the universe is expanding, but probably it's gonna pull back.

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Speaker 1: Probably gravity is going to be strong enough to pull

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Speaker 1: everything back together and maybe make a big crunch. Or

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Speaker 1: if not, then things are gonna gradually slow down due

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Speaker 1: to gravity as they drift away from each other. So

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Speaker 1: the question until twenty years ago was how quickly is

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Speaker 1: the universe decelerating? How quickly are things slowing down? And

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Speaker 1: then they went out and measured this, because, as we

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Speaker 1: talked about earlier, you always got to go out and

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Speaker 1: see what's really going on in the universe. And they

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Speaker 1: discovered by looking at how far away stars were and

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Speaker 1: looking back into the past to see how quickly they

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Speaker 1: were moving away from us a long time ago, that

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Speaker 1: the universe wasn't slowing down at all, that this expansion

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Speaker 1: was in fact accelerating, that every year things were moving

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Speaker 1: away from us faster and faster. So this blew everybody's minds.

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Speaker 1: They're like, oh my gosh, not only is the universe expanding,

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Speaker 1: but it's accelerating. What could be doing? And so they

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Speaker 1: replaced that big question mark with a fancy phrase called

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Speaker 1: dark energy, and that's about where we are today. Dark

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Speaker 1: energy is just the name for this discovery for which

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Speaker 1: we have no real explanation, right because without that observation,

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Speaker 1: I mean, like you said, we would expect the universe

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Speaker 1: to crunch back down again, right because gravity sort of

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Speaker 1: doesn't give up, Like, even if things are super far away,

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Speaker 1: they're still being pulled a little bit by gravity. And

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Speaker 1: so eventually that acceleration that floors should bring everything back

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Speaker 1: together into a little tiny dot. Right. It depends a

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Speaker 1: little bit on the balance between gravity and the initial velocity.

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Speaker 1: It's possible, because gravity gets weaker as distance grows, that

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Speaker 1: we could have lived in the universe with no dark energy,

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Speaker 1: that didn't crunch back down together, that just spread out forever,

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Speaker 1: if there was sort of enough initial energy, just in

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Speaker 1: the same way that you can, for example, throw a

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Speaker 1: ball off the surface of the Earth at high enough

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Speaker 1: velocity that it never ever comes back, even in the

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Speaker 1: infinite future, has enough energy to escape Earth's potential. Well,

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Speaker 1: so it was possible that things expanded out forever. But

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Speaker 1: until we discovered dark energy, we never imagined that it

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Speaker 1: could actually be accelerating outward, that things could be stretched out,

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Speaker 1: that new space could be being made between those galaxies. Right,

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Speaker 1: And so you gave that acceleration of the expanding universe

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Speaker 1: that's expanding faster and faster. You give it the name

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Speaker 1: dark energy because it must be some kind of energy, right,

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Speaker 1: because you don't know what else it could be. We

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Speaker 1: don't know what else this could be. One sort of

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Speaker 1: category of explanations is something we call the cosmological constant.

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Speaker 1: And this is just like a number that you stick

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Speaker 1: into Einstein's general relativity equations and it reflects some sort

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Speaker 1: of like potential energy of the universe. Remember we talked

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Speaker 1: to the podcast about how the space is filled with

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Speaker 1: quantum fields, right, all of space has fields, and it

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Speaker 1: fields for the electrons, fields for photons, feels for all

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Speaker 1: the different kinds of particles. And these fields can do

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Speaker 1: different things. They can wiggle, which is like having kinetic

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Speaker 1: energy the way like a ball rolling down the hill

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Speaker 1: has kinnectic or g But the fields can also have

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Speaker 1: potential energy energy stored in them because of their configuration,

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Speaker 1: like a ball sitting at the top of a hill

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Speaker 1: that isn't yet moving really fast. So if you have

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Speaker 1: a field with a lot of potential energy, that creates

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Speaker 1: this outward pressure due to this cosmological constant that comes

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Speaker 1: from that field. And so we sort of like stuck

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Speaker 1: this number into Einstein's theory and we gave it the

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Speaker 1: right number to explain the expansion that we see. But

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Speaker 1: we can't explain that number. It's just like, well, here's

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Speaker 1: a number, we measured it. We don't know why it

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Speaker 1: is that number or what field could be generating this

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Speaker 1: potential energy. It's still a really big mystery, and I

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Speaker 1: feel like that's kind of the reason you gave it

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Speaker 1: a name, right, It was was sort of because it

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Speaker 1: is sort of a term in your equations of the universe,

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Speaker 1: in Einstein's equations, Right, like my kids are growing faster

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Speaker 1: and faster, but I don't give a name to the

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Speaker 1: idea or the phenomenon of them growing faster and faster.

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Speaker 1: Or like if the universe he saw that it was

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Speaker 1: growing faster and faster, you might just say, oh, the

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Speaker 1: universe is growing faster and faster. But because you have

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Speaker 1: these equations and you have you have like an actual

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Speaker 1: term that kind of describes that or explain this expansion.

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Speaker 1: You give it a name, and we can also calculate

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Speaker 1: how much energy is necessary for this to happen, Like

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Speaker 1: you find the number you have to put into Einstein's

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Speaker 1: equation to explain this, and then you can calculate what

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Speaker 1: sort of energy density is required in space to cause

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Speaker 1: that term. Right, this cosmological constant isn't just like an

429
00:22:19,200 --> 00:22:23,600
Speaker 1: abstract idea. It reflects like some potential energy stored in

430
00:22:23,760 --> 00:22:26,600
Speaker 1: space itself, and then we can calculate that energy we

431
00:22:26,600 --> 00:22:28,720
Speaker 1: can compare to other things and we find that, Wow,

432
00:22:28,960 --> 00:22:32,119
Speaker 1: this potential energy is more than all of the energy

433
00:22:32,200 --> 00:22:35,240
Speaker 1: stored in all the stars and the galaxies and the

434
00:22:35,320 --> 00:22:38,320
Speaker 1: dust and all of the dark matter and all of

435
00:22:38,359 --> 00:22:40,800
Speaker 1: the stuff we see in the universe. It's like more

436
00:22:40,840 --> 00:22:44,400
Speaker 1: than twice as much energy as everything else in the universe.

437
00:22:44,800 --> 00:22:47,280
Speaker 1: So it's a huge quantity. It's a big part of

438
00:22:47,280 --> 00:22:50,000
Speaker 1: the recipe of the universe, right, And it's sort of

439
00:22:50,119 --> 00:22:52,840
Speaker 1: energy because I mean, it's one thing to grow space,

440
00:22:53,040 --> 00:22:56,399
Speaker 1: but it's also another thing to like push the things

441
00:22:56,840 --> 00:22:59,000
Speaker 1: along that are in space. Right, Like if I was

442
00:22:59,080 --> 00:23:01,520
Speaker 1: growing my house, they can just grow the house, it

443
00:23:01,560 --> 00:23:04,159
Speaker 1: would also have to like move the beds on the

444
00:23:04,320 --> 00:23:08,320
Speaker 1: table everything out further out towards the walls more, right,

445
00:23:08,800 --> 00:23:11,800
Speaker 1: And so that that takes energy, right, It takes energy. Yeah,

446
00:23:11,840 --> 00:23:14,679
Speaker 1: And what this means is that space has energy in

447
00:23:14,720 --> 00:23:17,280
Speaker 1: it like this stuff because it's part of the potential

448
00:23:17,359 --> 00:23:20,560
Speaker 1: energy of space itself. It doesn't get diluted when you

449
00:23:20,640 --> 00:23:23,320
Speaker 1: make new space. When you stretch out the space between

450
00:23:23,359 --> 00:23:27,359
Speaker 1: two galaxies, then you're creating more dark energy because you

451
00:23:27,440 --> 00:23:31,000
Speaker 1: are creating more space. So it's really weird and counterintuitive.

452
00:23:31,240 --> 00:23:34,240
Speaker 1: You know. It means that like energy is creating more energy.

453
00:23:34,400 --> 00:23:35,879
Speaker 1: And for those of you who worry about, like, well

454
00:23:35,880 --> 00:23:38,400
Speaker 1: where does this energy come from? Right, Like, how can

455
00:23:38,440 --> 00:23:41,600
Speaker 1: you just do that? Doesn't that violate conservation of energy? Yes,

456
00:23:41,760 --> 00:23:44,680
Speaker 1: and biolate it's conservation of energy, which it turns out,

457
00:23:45,000 --> 00:23:48,080
Speaker 1: is not a deep and fundamental principle of the universe.

458
00:23:48,200 --> 00:23:51,320
Speaker 1: Only a fundamental principle of universe is where space is static,

459
00:23:51,359 --> 00:23:54,000
Speaker 1: where the rules are not changing as a function of time.

460
00:23:54,040 --> 00:23:55,920
Speaker 1: But we don't seem to live in that kind of universe.

461
00:23:55,960 --> 00:23:58,400
Speaker 1: We live in the universe where the space is changing

462
00:23:58,640 --> 00:24:01,760
Speaker 1: and so energy is not served. It just like appears

463
00:24:01,840 --> 00:24:04,600
Speaker 1: seemingly out of nowhere, right, But I feel like that's

464
00:24:04,640 --> 00:24:07,800
Speaker 1: only true if you assume that dark energy is sort

465
00:24:07,800 --> 00:24:10,679
Speaker 1: of inherent to space, you know what I mean? Like

466
00:24:10,680 --> 00:24:13,119
Speaker 1: the dark energy also be you know, the result of

467
00:24:13,240 --> 00:24:16,040
Speaker 1: something already in space or something that that is limited.

468
00:24:16,200 --> 00:24:18,199
Speaker 1: A dark energy could be a lot of things. But

469
00:24:18,280 --> 00:24:20,359
Speaker 1: what we do know is that it doesn't get diluted

470
00:24:20,400 --> 00:24:22,800
Speaker 1: as space expands, so you can come up with something

471
00:24:22,880 --> 00:24:25,679
Speaker 1: else that also has that property. The only thing we

472
00:24:25,720 --> 00:24:29,200
Speaker 1: know about is vacuum energy is the potential energy that's

473
00:24:29,200 --> 00:24:31,840
Speaker 1: the only thing that doesn't get diluted as space expand.

474
00:24:32,040 --> 00:24:35,080
Speaker 1: Matter and radiation, those kind of things, they do get

475
00:24:35,119 --> 00:24:37,880
Speaker 1: diluted as space expands. But then again, we don't really

476
00:24:37,920 --> 00:24:40,360
Speaker 1: know what space is, right, and so maybe we need

477
00:24:40,400 --> 00:24:43,400
Speaker 1: a whole new concept for how space works and what

478
00:24:43,440 --> 00:24:45,520
Speaker 1: it means. Right. That's kind of what I mean is that,

479
00:24:45,640 --> 00:24:49,159
Speaker 1: you know, you don't know where it's coming from, and

480
00:24:49,200 --> 00:24:52,280
Speaker 1: like you said, it's changed over the years since the

481
00:24:52,320 --> 00:24:55,280
Speaker 1: beginning of the universe. So even that statement that it

482
00:24:55,359 --> 00:24:57,320
Speaker 1: is sort of inherent to space, we don't really quite

483
00:24:57,400 --> 00:24:59,480
Speaker 1: know for sure, right, We definitely do not know for sure.

484
00:24:59,520 --> 00:25:01,680
Speaker 1: We're in the part to this investigation where we're trying

485
00:25:01,680 --> 00:25:04,879
Speaker 1: to just like build a general structure of an idea

486
00:25:04,960 --> 00:25:08,200
Speaker 1: and ask, like what shape does this idea have to take?

487
00:25:08,440 --> 00:25:09,960
Speaker 1: What can we fit into it? And we start with

488
00:25:10,040 --> 00:25:12,680
Speaker 1: what we think are the simplest ideas. You know, maybe

489
00:25:12,680 --> 00:25:15,440
Speaker 1: it's like this, maybe it's like that, and if that works, great,

490
00:25:15,480 --> 00:25:17,240
Speaker 1: and if it doesn't work, then we need to add

491
00:25:17,280 --> 00:25:19,920
Speaker 1: bells and whistles or come up with new ideas. We're

492
00:25:19,960 --> 00:25:22,680
Speaker 1: definitely in the very early days. Yeah, and even though

493
00:25:22,720 --> 00:25:27,280
Speaker 1: we are still only I guess inventing the general shape

494
00:25:27,320 --> 00:25:30,399
Speaker 1: of the general idea. There are some problems with this

495
00:25:30,480 --> 00:25:33,680
Speaker 1: general idea, ones that have to do with the beginning

496
00:25:33,720 --> 00:25:36,199
Speaker 1: of the universe, and so let's get into what is

497
00:25:36,240 --> 00:25:38,679
Speaker 1: the problem with dark energy, But first let's take a

498
00:25:38,760 --> 00:25:53,880
Speaker 1: quick break. All right, we're talking about dark energy, and

499
00:25:54,080 --> 00:25:56,000
Speaker 1: I guess there's a problem with dark energy. I mean,

500
00:25:56,000 --> 00:25:58,720
Speaker 1: it's not just making the universe bigger and bigger, faster

501
00:25:58,840 --> 00:26:02,320
Speaker 1: and faster, which eventually lead to the heat death of

502
00:26:02,359 --> 00:26:06,960
Speaker 1: the universe, the universe dying out of basically order. There's

503
00:26:07,000 --> 00:26:09,960
Speaker 1: also some problems with it being able to explain the

504
00:26:10,280 --> 00:26:14,639
Speaker 1: early universe exactly. What we've tried so far is saying

505
00:26:15,040 --> 00:26:17,560
Speaker 1: maybe that there's just a number we can stick in

506
00:26:17,600 --> 00:26:20,800
Speaker 1: Einstein's equation, that like every unit of space has a

507
00:26:20,840 --> 00:26:23,320
Speaker 1: certain amount of dark energy. And there's a few different

508
00:26:23,320 --> 00:26:25,680
Speaker 1: things going on here that it's important to sort of unravel.

509
00:26:26,040 --> 00:26:29,280
Speaker 1: One is that, like, we assume that dark energy is constant,

510
00:26:29,359 --> 00:26:31,680
Speaker 1: but when we say constant, we mean like any chunk

511
00:26:31,720 --> 00:26:34,359
Speaker 1: of space has the same amount of this dark energy,

512
00:26:34,440 --> 00:26:38,960
Speaker 1: this potential energy, this cosmological constant. But as the universe expands,

513
00:26:39,000 --> 00:26:41,240
Speaker 1: even if every chunk of space has the same amount

514
00:26:41,240 --> 00:26:44,360
Speaker 1: of dark energy. Dark energy is fraction of the universe

515
00:26:44,400 --> 00:26:48,359
Speaker 1: itself is growing, right, because everything else gets diluted away.

516
00:26:48,520 --> 00:26:50,880
Speaker 1: So the dark energy fraction of the universe we don't

517
00:26:50,920 --> 00:26:54,200
Speaker 1: think is constant dark energy. We thought maybe was constant

518
00:26:54,480 --> 00:26:58,399
Speaker 1: like per chunk of space. That's what the cosmological constant is.

519
00:26:58,600 --> 00:27:00,879
Speaker 1: That was the basic idea, like had a fixed amount

520
00:27:00,960 --> 00:27:03,840
Speaker 1: of dark energy per unit of space, and then see

521
00:27:03,960 --> 00:27:06,680
Speaker 1: if that evolves the universe through time in the way

522
00:27:06,720 --> 00:27:09,720
Speaker 1: that we see it actually happening out there, right, And

523
00:27:09,760 --> 00:27:12,600
Speaker 1: what you found is that it doesn't write like a

524
00:27:12,680 --> 00:27:14,560
Speaker 1: number you have just taken now to the equation to

525
00:27:14,600 --> 00:27:18,240
Speaker 1: explain the current acceleration of the expansion of the universe works.

526
00:27:18,359 --> 00:27:20,879
Speaker 1: But then if you you know, you look back in time,

527
00:27:20,960 --> 00:27:24,720
Speaker 1: that number doesn't work exactly. A cosmological constant doesn't quite

528
00:27:24,720 --> 00:27:27,040
Speaker 1: describe the history that we see. And we can measure

529
00:27:27,080 --> 00:27:29,879
Speaker 1: this in two different ways. We have late time measurements

530
00:27:30,040 --> 00:27:32,919
Speaker 1: and we have early time measurements, and they don't quite agree.

531
00:27:33,240 --> 00:27:35,760
Speaker 1: So the late time measurements are like, let's go out

532
00:27:35,800 --> 00:27:38,080
Speaker 1: and measure the expansion of the universe. How fast are

533
00:27:38,080 --> 00:27:40,880
Speaker 1: things moving and how fast are they accelerating? And these

534
00:27:40,920 --> 00:27:43,440
Speaker 1: are the famous discoveries of dark energy, you know, for example,

535
00:27:43,480 --> 00:27:46,080
Speaker 1: looking at type one A supernova, that kind of stuff.

536
00:27:46,320 --> 00:27:48,919
Speaker 1: We can also look at the very very early universe

537
00:27:49,200 --> 00:27:51,760
Speaker 1: and trying to measure how much dark energy was there

538
00:27:51,760 --> 00:27:55,680
Speaker 1: back then, measure that using like the cosmic microwave background radiation.

539
00:27:56,200 --> 00:27:57,879
Speaker 1: We measure that, and then we plug that into our

540
00:27:57,880 --> 00:28:01,159
Speaker 1: simulations and try to predict how much acceleration there was

541
00:28:01,280 --> 00:28:03,800
Speaker 1: and how fast things should be moving today. And those

542
00:28:03,840 --> 00:28:07,240
Speaker 1: two numbers don't agree, right, and so there's some sort

543
00:28:07,280 --> 00:28:09,879
Speaker 1: of mismatch there, Like there doesn't seem to be enough

544
00:28:10,000 --> 00:28:13,080
Speaker 1: dark energy in the early universe to get us going

545
00:28:13,200 --> 00:28:15,680
Speaker 1: as fast as we seem to be going today. I

546
00:28:15,720 --> 00:28:18,000
Speaker 1: feel like there's two things, and maybe people are getting confused.

547
00:28:18,040 --> 00:28:21,000
Speaker 1: So like, right now the universe is expanding at a

548
00:28:21,119 --> 00:28:25,600
Speaker 1: velocity that's faster than it used to be. That's for sure,

549
00:28:25,800 --> 00:28:28,840
Speaker 1: like the universe expanding faster than it used to expand before.

550
00:28:29,760 --> 00:28:32,880
Speaker 1: But you can also talk about the acceleration of the universe,

551
00:28:32,920 --> 00:28:35,480
Speaker 1: which is the idea that it's growing faster and faster

552
00:28:35,600 --> 00:28:37,760
Speaker 1: each year. And so I think you're saying that even

553
00:28:37,800 --> 00:28:41,080
Speaker 1: the acceleration now is faster than it used to be,

554
00:28:41,320 --> 00:28:44,959
Speaker 1: Like the universe is somehow hitting the gas pedal even harder. Today.

555
00:28:45,080 --> 00:28:46,760
Speaker 1: What we do is we measure this thing called the

556
00:28:46,960 --> 00:28:50,080
Speaker 1: Hubble constant, you know, which is terribly named because it's

557
00:28:50,080 --> 00:28:52,480
Speaker 1: not a constant. It's a measure of how fast the

558
00:28:52,560 --> 00:28:55,320
Speaker 1: universe is expanding. And we can measure it like in

559
00:28:55,440 --> 00:28:58,400
Speaker 1: recent times, because we can look in our neighborhood and

560
00:28:58,400 --> 00:29:00,920
Speaker 1: see like how fast is stuff looking away from us?

561
00:29:00,920 --> 00:29:03,680
Speaker 1: How fast was stuff moving away from us pretty recently.

562
00:29:04,040 --> 00:29:06,640
Speaker 1: We can use that to measure this Hubble constant, which

563
00:29:06,680 --> 00:29:09,320
Speaker 1: is like the derivative of the scale factor of the

564
00:29:09,400 --> 00:29:12,440
Speaker 1: universe normalized to itself. And so that's like a measure

565
00:29:12,480 --> 00:29:14,840
Speaker 1: of the expansion rate. And what we can do in

566
00:29:14,840 --> 00:29:17,640
Speaker 1: the early universe is we can measure like how much

567
00:29:17,720 --> 00:29:20,760
Speaker 1: dark energy was there. We can use that to predict

568
00:29:20,880 --> 00:29:24,680
Speaker 1: the acceleration of the universe, which should give us like

569
00:29:24,880 --> 00:29:27,640
Speaker 1: the velocity. It's sort of like saying, all right, you

570
00:29:27,920 --> 00:29:30,640
Speaker 1: started your car, you were pressing on the gas pedal

571
00:29:30,640 --> 00:29:33,880
Speaker 1: a certain amount, how fast should you be going after

572
00:29:33,960 --> 00:29:36,000
Speaker 1: a minute? And if the rate we're measuring, like how

573
00:29:36,080 --> 00:29:39,200
Speaker 1: faster car is going right now is too fast, and

574
00:29:39,280 --> 00:29:41,720
Speaker 1: we're like, maybe you were pressing the gas pedal faster

575
00:29:41,840 --> 00:29:44,400
Speaker 1: than you thought. You were right, right, But I wonder

576
00:29:44,440 --> 00:29:47,160
Speaker 1: if maybe the folks are getting confused with because there

577
00:29:47,280 --> 00:29:50,040
Speaker 1: there's also the idea in the early universe of inflation,

578
00:29:50,160 --> 00:29:53,240
Speaker 1: right and the Big Bang? Now was inflation and the

579
00:29:53,240 --> 00:29:56,480
Speaker 1: Big bank also due to dark energy? Or was it

580
00:29:56,920 --> 00:29:59,680
Speaker 1: you know, that super rapid expansion like a second after

581
00:29:59,720 --> 00:30:02,360
Speaker 1: the Uni verse was born, the universe expanded like tang

582
00:30:02,440 --> 00:30:05,680
Speaker 1: to the twenties something or crazy amount. Was that also

583
00:30:05,760 --> 00:30:07,760
Speaker 1: due to dark energy? Or was that something due to

584
00:30:07,880 --> 00:30:10,760
Speaker 1: something else? Entirely, we just really don't know. We know

585
00:30:10,880 --> 00:30:14,640
Speaker 1: that there are similar right. They both expand space very rapidly.

586
00:30:14,960 --> 00:30:17,720
Speaker 1: We don't know if they're connected. There are some theories

587
00:30:17,760 --> 00:30:21,520
Speaker 1: of inflation that try to connect dark energy with inflation,

588
00:30:21,640 --> 00:30:23,840
Speaker 1: but there's some theories of inflation that are totally separate

589
00:30:23,840 --> 00:30:26,960
Speaker 1: that say, no, it's due to this weird inflaton field

590
00:30:26,960 --> 00:30:30,600
Speaker 1: that has its own potential energy which rapidly expanded space,

591
00:30:31,200 --> 00:30:34,040
Speaker 1: and so we just don't know. We do notice that

592
00:30:34,080 --> 00:30:37,080
Speaker 1: they are similar, right, But these questions about dark energy

593
00:30:37,120 --> 00:30:39,840
Speaker 1: assume just inflation happened, and like, don't ask too many

594
00:30:39,920 --> 00:30:42,680
Speaker 1: questions about it. Let's just start from the post inflation

595
00:30:42,800 --> 00:30:46,440
Speaker 1: universe and try to understand the expansion history from that point. Oh,

596
00:30:46,600 --> 00:30:49,080
Speaker 1: I see, when you're talking about early dark energy, you

597
00:30:49,120 --> 00:30:53,719
Speaker 1: mean like post inflation dark energy exactly, not that early

598
00:30:54,840 --> 00:30:59,360
Speaker 1: that I mean, not pre early, late earlier. That's right,

599
00:30:59,360 --> 00:31:01,720
Speaker 1: because the early this thing that we can actually measure

600
00:31:02,000 --> 00:31:04,680
Speaker 1: comes from about four thousand years after the beginning of

601
00:31:04,720 --> 00:31:07,760
Speaker 1: the universe. This is the cosmic microwave background radiation. And

602
00:31:07,760 --> 00:31:10,120
Speaker 1: we can look at these wiggles in the microwave spectrum

603
00:31:10,160 --> 00:31:13,200
Speaker 1: in the sky, which is light from that very early plasma,

604
00:31:13,600 --> 00:31:15,200
Speaker 1: and we can get a sense from what was going

605
00:31:15,200 --> 00:31:17,160
Speaker 1: on back then, and so that gives us actually a

606
00:31:17,160 --> 00:31:19,880
Speaker 1: measurement of how much dark energy there was back then,

607
00:31:20,200 --> 00:31:23,360
Speaker 1: which let's just calculate the acceleration from that point, not

608
00:31:23,400 --> 00:31:25,560
Speaker 1: all the way back to inflation. Like that's a murky

609
00:31:25,640 --> 00:31:28,400
Speaker 1: mystery for another day, right, But wouldn't that sort of

610
00:31:28,400 --> 00:31:31,480
Speaker 1: confuse things like at what point do you think this

611
00:31:31,680 --> 00:31:34,600
Speaker 1: potential infloton field or whatever it is that costs a

612
00:31:34,640 --> 00:31:37,960
Speaker 1: big bang or the inflation you know, drop off and

613
00:31:38,080 --> 00:31:41,520
Speaker 1: gave way to dark energy, Like couldn't there have been overlapped?

614
00:31:41,520 --> 00:31:44,600
Speaker 1: How do you know? Like what cause inflation isn't like

615
00:31:44,680 --> 00:31:48,640
Speaker 1: affecting us today. Yeah, we don't write it could be connected.

616
00:31:48,720 --> 00:31:51,280
Speaker 1: The basic ideas are the same. That you have some

617
00:31:51,400 --> 00:31:53,880
Speaker 1: field with a lot of potential energy, you put that

618
00:31:53,920 --> 00:31:58,080
Speaker 1: into Einstein's equations. It causes this repulsive effect on the

619
00:31:58,200 --> 00:32:00,920
Speaker 1: universe to stretch it and expand. It could be that

620
00:32:01,080 --> 00:32:04,000
Speaker 1: inflation has a different kind of potential energy from a

621
00:32:04,040 --> 00:32:07,400
Speaker 1: different field, this in photon field, or it could be related. Also,

622
00:32:07,480 --> 00:32:09,640
Speaker 1: we don't understand either of them. We don't understand why

623
00:32:09,640 --> 00:32:12,600
Speaker 1: inflation happened. We don't understand why it stopped. We don't

624
00:32:12,880 --> 00:32:15,320
Speaker 1: understand if it did in fact stop, or if dark

625
00:32:15,440 --> 00:32:18,160
Speaker 1: energy is an extension of it. Yeah, we're clueless about

626
00:32:18,200 --> 00:32:21,560
Speaker 1: all that stuff. So basically we don't know anything. Daniel.

627
00:32:22,000 --> 00:32:24,360
Speaker 1: We're in the dark about the whole dark energy thing.

628
00:32:24,440 --> 00:32:26,880
Speaker 1: We're mostly in the dark. Until very recently, though, it

629
00:32:27,000 --> 00:32:29,760
Speaker 1: seemed like if you assume that there was a fixed

630
00:32:29,800 --> 00:32:33,040
Speaker 1: amount of dark energy after inflation, after somehow the in

631
00:32:33,080 --> 00:32:35,960
Speaker 1: photon field died away or whatever, that if you assume

632
00:32:36,000 --> 00:32:37,680
Speaker 1: there was a fixed amount of dark energy, that it

633
00:32:37,760 --> 00:32:41,480
Speaker 1: mostly described the universe like our rough calculations and early

634
00:32:41,520 --> 00:32:44,840
Speaker 1: measurements suggested things were banging on that the measurements we

635
00:32:44,920 --> 00:32:48,120
Speaker 1: had of this cosmic microwave background radiation told us a

636
00:32:48,120 --> 00:32:50,360
Speaker 1: certain amount of dark energy. You put that into the

637
00:32:50,360 --> 00:32:52,400
Speaker 1: equations and ran them forward in time. You've got a

638
00:32:52,480 --> 00:32:54,360
Speaker 1: universe that looked a lot like the one we see

639
00:32:54,360 --> 00:32:56,680
Speaker 1: out there right now. But as these measurements got more

640
00:32:56,680 --> 00:32:59,400
Speaker 1: and more precise than a problem emerged and they didn't

641
00:32:59,600 --> 00:33:02,400
Speaker 1: quite work. Oh, I see, all right, So I'm trying

642
00:33:02,440 --> 00:33:04,440
Speaker 1: to put my head in the place of a physicist.

643
00:33:04,440 --> 00:33:07,880
Speaker 1: So you're saying that the Big Bang happened, inflation happened, done,

644
00:33:09,040 --> 00:33:10,880
Speaker 1: like we're going to put a market there and ignore

645
00:33:10,960 --> 00:33:14,240
Speaker 1: everything that happened before. Like after information, we're going to

646
00:33:14,400 --> 00:33:17,160
Speaker 1: reset our thinking. We're going to assume that there's something

647
00:33:17,160 --> 00:33:22,240
Speaker 1: called dark energy that's continuing to keep the universe expanding

648
00:33:22,240 --> 00:33:24,360
Speaker 1: at a faster rate. And you're saying that before we

649
00:33:24,480 --> 00:33:26,280
Speaker 1: used to be able to just plug one number in

650
00:33:26,320 --> 00:33:29,600
Speaker 1: and it sort of worked like it it mostly described things,

651
00:33:29,600 --> 00:33:32,520
Speaker 1: But now now it doesn't quite work. Now it doesn't

652
00:33:32,560 --> 00:33:35,360
Speaker 1: quite work exactly. Now the universe seems to be expanding

653
00:33:35,400 --> 00:33:38,600
Speaker 1: at late times more quickly than we can explain with

654
00:33:38,640 --> 00:33:40,840
Speaker 1: the amount of dark energy that we measure from the

655
00:33:40,880 --> 00:33:44,640
Speaker 1: early times. Like whoever was driving the universe back then

656
00:33:44,720 --> 00:33:46,560
Speaker 1: with dark energy, they put their foot on the gas

657
00:33:46,600 --> 00:33:49,040
Speaker 1: pedal at a certain level. But now when we look

658
00:33:49,080 --> 00:33:50,760
Speaker 1: at the speed of the universe, it seems to be

659
00:33:50,800 --> 00:33:53,960
Speaker 1: going faster than can be explained by that amount of gas.

660
00:33:54,120 --> 00:33:57,480
Speaker 1: So that's the question. Is the cosmological constant actually a

661
00:33:57,480 --> 00:33:59,880
Speaker 1: constant or do we need to make it more complicated?

662
00:34:00,240 --> 00:34:02,040
Speaker 1: Right that number used to plug in that used to

663
00:34:02,040 --> 00:34:05,720
Speaker 1: work before now doesn't work before, which means that basically

664
00:34:05,760 --> 00:34:08,080
Speaker 1: it's not a number. Kind of yeah, now it's a function.

665
00:34:08,320 --> 00:34:10,839
Speaker 1: Right now we need a new little bit, meaning like

666
00:34:10,920 --> 00:34:14,759
Speaker 1: the amount of dark energy per block of space is

667
00:34:14,880 --> 00:34:17,440
Speaker 1: or it has been changing. That's the question exactly, And

668
00:34:17,480 --> 00:34:20,080
Speaker 1: so early dark energy is an attempt to try to

669
00:34:20,160 --> 00:34:23,480
Speaker 1: fix this problem is to say, well, maybe there's dark energy,

670
00:34:23,560 --> 00:34:25,719
Speaker 1: which is just a number and it's constant. But now

671
00:34:25,800 --> 00:34:28,560
Speaker 1: let's add a new thing. Let's not just change dark energy.

672
00:34:28,640 --> 00:34:31,560
Speaker 1: Let's add a new kind of expansion to the universe,

673
00:34:31,640 --> 00:34:35,439
Speaker 1: like a new unexplained expansion that's going to only take

674
00:34:35,480 --> 00:34:38,400
Speaker 1: place in the early universe, Like there was dark energy,

675
00:34:38,440 --> 00:34:41,600
Speaker 1: which is accelerating the expansion the universe. Plus let's add

676
00:34:41,640 --> 00:34:44,800
Speaker 1: a new bit which only turned on an early universe,

677
00:34:45,000 --> 00:34:48,279
Speaker 1: got things going extra fast, and then disappeared, which is

678
00:34:48,280 --> 00:34:50,280
Speaker 1: why we don't see it today. So that's the idea

679
00:34:50,280 --> 00:34:52,720
Speaker 1: of early dark energy, is to try to like patch

680
00:34:52,840 --> 00:34:55,279
Speaker 1: up this problem with dark energy, not by saying dark

681
00:34:55,360 --> 00:34:57,839
Speaker 1: energy changes with time, but by saying there was a

682
00:34:57,880 --> 00:35:01,520
Speaker 1: new thing, yet another way to expanding universe, but this

683
00:35:01,560 --> 00:35:05,040
Speaker 1: one only lasted from like zero to four years after

684
00:35:05,040 --> 00:35:08,080
Speaker 1: the Big Bang? Oh? I see wait? So um, so

685
00:35:08,239 --> 00:35:10,319
Speaker 1: you I think you're saying that early dark energy is

686
00:35:10,320 --> 00:35:14,040
Speaker 1: not dark energy. So early dark energy is not dark

687
00:35:14,120 --> 00:35:17,600
Speaker 1: energy exactly. It's a new thing that is like dark

688
00:35:17,719 --> 00:35:20,920
Speaker 1: energy and also kind of like inflation, right, and that

689
00:35:21,040 --> 00:35:24,280
Speaker 1: it expands the universe due to some potential energy field,

690
00:35:24,400 --> 00:35:28,279
Speaker 1: but it's somehow also disappeared before the CNB, right, so

691
00:35:28,320 --> 00:35:30,600
Speaker 1: that it doesn't like mess up everything we see later. Right.

692
00:35:30,840 --> 00:35:33,600
Speaker 1: I guess an early hooge would be so foreign to

693
00:35:33,760 --> 00:35:36,040
Speaker 1: regular hooge that you would have to call it a

694
00:35:36,040 --> 00:35:39,279
Speaker 1: different whoree. I think that's what you're thinking, is a physicist,

695
00:35:41,560 --> 00:35:44,360
Speaker 1: what gives the sense of the scale here? How different

696
00:35:44,680 --> 00:35:49,719
Speaker 1: is this post inflation, post Big Bang dark energy expansion

697
00:35:49,880 --> 00:35:52,120
Speaker 1: than the expansion we have now due to dark energy.

698
00:35:52,280 --> 00:35:54,600
Speaker 1: It's turned out to be pretty significant. You know, early

699
00:35:54,640 --> 00:35:56,920
Speaker 1: on when we were measuring these things for the first time,

700
00:35:57,440 --> 00:35:59,800
Speaker 1: we really didn't know how fast the universe was expanding,

701
00:35:59,840 --> 00:36:02,280
Speaker 1: and we had big error bars on all of our measurements,

702
00:36:02,280 --> 00:36:04,839
Speaker 1: and so things seemed to kind of disagree a little bit,

703
00:36:04,880 --> 00:36:07,279
Speaker 1: but nobody was worried about it. Now these measurements have

704
00:36:07,320 --> 00:36:10,880
Speaker 1: gotten really really precise, and the difference between the predictions

705
00:36:10,880 --> 00:36:13,200
Speaker 1: for how fast we are expanding and how fast we

706
00:36:13,239 --> 00:36:16,040
Speaker 1: should be expanding if dark energy was constant and there

707
00:36:16,080 --> 00:36:19,040
Speaker 1: was no early dark energy are different by about ten

708
00:36:19,160 --> 00:36:22,320
Speaker 1: per cent. So this is measurements of the Hubble constant,

709
00:36:22,400 --> 00:36:25,000
Speaker 1: and like the late measurements, the ones using like supernova

710
00:36:25,040 --> 00:36:27,440
Speaker 1: and sephids and other kinds of stuff, they measured this

711
00:36:27,480 --> 00:36:30,440
Speaker 1: Hubble constant to be about seventy three, where the units

712
00:36:30,440 --> 00:36:34,919
Speaker 1: are kilometers per second per mega PARSEEK and the early ones,

713
00:36:35,000 --> 00:36:37,320
Speaker 1: the ones that come from the CNB where we measure

714
00:36:37,360 --> 00:36:39,480
Speaker 1: what was going on in the early universe, how much

715
00:36:39,520 --> 00:36:42,360
Speaker 1: dark energy there was, and then predict how fast we

716
00:36:42,360 --> 00:36:46,400
Speaker 1: should be accelerating. They predict sixty seven, So that's seventy

717
00:36:46,440 --> 00:36:49,640
Speaker 1: three versus sixty seven, and the uncertainties are getting pretty

718
00:36:49,640 --> 00:36:52,560
Speaker 1: pretty small, Like, these are precise measurements now. The Plank

719
00:36:52,640 --> 00:36:56,279
Speaker 1: satellite gave us really precise measurements of the CMB, and

720
00:36:56,320 --> 00:36:58,439
Speaker 1: we have lots and lots of supernova now and lots

721
00:36:58,480 --> 00:37:00,920
Speaker 1: of other kind of ways to measure the leration today.

722
00:37:01,080 --> 00:37:03,680
Speaker 1: So the difference between these two has become pretty significant.

723
00:37:03,719 --> 00:37:07,040
Speaker 1: It's like five or six sigma, which means that it's like,

724
00:37:07,160 --> 00:37:10,160
Speaker 1: doesn't seem to be just a statistical error. It seems

725
00:37:10,200 --> 00:37:13,120
Speaker 1: like it might be real. Well, it's it's it's ten

726
00:37:13,160 --> 00:37:16,279
Speaker 1: percent different, but you're saying that your confidence in that

727
00:37:16,400 --> 00:37:20,640
Speaker 1: ten percent difference is getting stronger. Exactly. People were sort

728
00:37:20,680 --> 00:37:23,080
Speaker 1: of thinking like, okay, these numbers are far apart, but

729
00:37:23,120 --> 00:37:25,000
Speaker 1: the errors are big. And then as we get more

730
00:37:25,000 --> 00:37:27,239
Speaker 1: and more data, sometimes what happens is that the things

731
00:37:27,320 --> 00:37:29,880
Speaker 1: sort of drift together. You're like, oh, two measurements of

732
00:37:29,880 --> 00:37:33,000
Speaker 1: the same thing using different ways as they get more precise,

733
00:37:33,320 --> 00:37:35,800
Speaker 1: if you're really measuring the same thing, they should eventually

734
00:37:35,800 --> 00:37:38,839
Speaker 1: agree and if you've understood all of your uncertainties and biases.

735
00:37:38,880 --> 00:37:41,400
Speaker 1: But these two things, as they've gotten more precise, have

736
00:37:41,560 --> 00:37:44,520
Speaker 1: stayed far apart. And so now yeah, they seem to

737
00:37:44,520 --> 00:37:47,000
Speaker 1: be far apart, and the confidence in both measurements is

738
00:37:47,000 --> 00:37:49,320
Speaker 1: pretty high. All right, So there's about a ten percent

739
00:37:49,360 --> 00:37:52,959
Speaker 1: difference in what we thought was the universe's expansion and

740
00:37:53,040 --> 00:37:57,600
Speaker 1: what it actually was before. And so just regular dark

741
00:37:57,719 --> 00:38:00,600
Speaker 1: energy on time late dark energy doesn't planet, and so

742
00:38:00,680 --> 00:38:03,399
Speaker 1: you need this concept of early dark energy. Early dark

743
00:38:03,480 --> 00:38:05,440
Speaker 1: energy is sort of in the same spirit of dark energy.

744
00:38:05,440 --> 00:38:07,720
Speaker 1: It's like, hold on the universe seems to be doing

745
00:38:07,840 --> 00:38:11,840
Speaker 1: something we can't explain. Let's just add another piece to

746
00:38:11,960 --> 00:38:13,920
Speaker 1: the mix and see if we can use that to

747
00:38:14,000 --> 00:38:16,480
Speaker 1: explain what's going on. Later we'll come in and figure

748
00:38:16,480 --> 00:38:18,680
Speaker 1: out why is this thing here, how does it work,

749
00:38:19,040 --> 00:38:22,560
Speaker 1: what exactly is creating this dark energy. The first step

750
00:38:22,640 --> 00:38:25,320
Speaker 1: is just like, you know, rough out an idea for

751
00:38:25,640 --> 00:38:28,160
Speaker 1: what pieces you need at what time to explain the

752
00:38:28,200 --> 00:38:30,920
Speaker 1: history that we see right right. Basically, it's sort of

753
00:38:30,960 --> 00:38:34,239
Speaker 1: like admitting that dark energy is changing. Right Like, the

754
00:38:34,280 --> 00:38:36,600
Speaker 1: original idea for dark energy was that it was some

755
00:38:36,680 --> 00:38:40,160
Speaker 1: sort of like constant inherent property of space and never changes.

756
00:38:40,600 --> 00:38:42,799
Speaker 1: But now you're sort of being forced to say, hey,

757
00:38:42,880 --> 00:38:45,400
Speaker 1: dark energy kind of is changing, So maybe it's not

758
00:38:45,719 --> 00:38:49,280
Speaker 1: some constant of the universem inherent property of space. Maybe

759
00:38:49,440 --> 00:38:51,880
Speaker 1: it's there are multiple dark energies, or maybe it's the

760
00:38:51,960 --> 00:38:54,560
Speaker 1: dark energy that's changing, yes, exactly. And there's a whole

761
00:38:54,560 --> 00:38:57,840
Speaker 1: category of ideas there. There's ones where there's multiple dark energies,

762
00:38:57,840 --> 00:39:00,520
Speaker 1: like a new one that appears early in the universe

763
00:39:00,600 --> 00:39:02,560
Speaker 1: and then disappears, right, which is why we don't seem

764
00:39:02,560 --> 00:39:05,480
Speaker 1: to see it today. Others where dark energy itself changes

765
00:39:05,840 --> 00:39:08,080
Speaker 1: and then stabilizes to a certain number and then is

766
00:39:08,160 --> 00:39:10,080
Speaker 1: fixed for the rest of the time of the universe.

767
00:39:10,400 --> 00:39:13,600
Speaker 1: There's a whole ridiculous spectrum of ideas. A lot of

768
00:39:13,600 --> 00:39:15,680
Speaker 1: particle theories I talked to say that most of them

769
00:39:15,680 --> 00:39:19,040
Speaker 1: are kind of ridiculous. They call them theoretical shenanigans. But

770
00:39:19,160 --> 00:39:21,520
Speaker 1: you know, it's just an effort to like try to

771
00:39:21,560 --> 00:39:24,160
Speaker 1: cook up a recipe that explains what we see and

772
00:39:24,160 --> 00:39:27,120
Speaker 1: then later figure out the details of that recipe right, right,

773
00:39:27,160 --> 00:39:32,000
Speaker 1: And in the meantime, let's confuse everybody with shortcuts here

774
00:39:32,080 --> 00:39:35,000
Speaker 1: to call things. Why not just call it dark shenanigans.

775
00:39:35,040 --> 00:39:39,480
Speaker 1: That would be valid. Oh man, that would have been awesome.

776
00:39:39,520 --> 00:39:41,480
Speaker 1: I would love if we had called it dark cinnanigans.

777
00:39:41,800 --> 00:39:45,200
Speaker 1: That's right, DS for because I have dark matter, dark energy,

778
00:39:45,239 --> 00:39:48,640
Speaker 1: and dark shenanigans. That seems like a really nice trifecta.

779
00:39:49,440 --> 00:39:53,480
Speaker 1: Sounds like what all physicists, and you know, the theorists

780
00:39:53,520 --> 00:39:56,120
Speaker 1: are going crazy with these ideas because every time you

781
00:39:56,200 --> 00:39:59,399
Speaker 1: give them an opening to be creative, then they come

782
00:39:59,480 --> 00:40:02,040
Speaker 1: up with all sort of silly ideas for like what

783
00:40:02,239 --> 00:40:05,360
Speaker 1: might be creating this. Lisa Randall, who's a famous theorist

784
00:40:05,400 --> 00:40:08,040
Speaker 1: who came up with the idea of extra dimensions. She

785
00:40:08,120 --> 00:40:10,920
Speaker 1: has a paper about rock and roll solutions to the

786
00:40:10,920 --> 00:40:15,360
Speaker 1: early universe that involves like new weird fields in space,

787
00:40:15,560 --> 00:40:18,480
Speaker 1: some of which rock back and forth to explain like

788
00:40:18,520 --> 00:40:20,319
Speaker 1: why they disappear, and some of them would you like,

789
00:40:20,680 --> 00:40:25,080
Speaker 1: roll away gradually and fade out before we could see them. Mhm.

790
00:40:25,280 --> 00:40:27,560
Speaker 1: So she called them rock and roll solutions literally in

791
00:40:27,560 --> 00:40:31,279
Speaker 1: her paper exactly. Her paper really is called rock and

792
00:40:31,360 --> 00:40:34,400
Speaker 1: Roll Solutions. It's pretty fun paper, but it's definitely in

793
00:40:34,440 --> 00:40:39,040
Speaker 1: the theoretical shenanigans category. Yeah, because I guess you, I mean,

794
00:40:39,239 --> 00:40:41,640
Speaker 1: before you saw dark energy was this constant thing, but

795
00:40:41,719 --> 00:40:43,759
Speaker 1: now knowing that it's changing, I mean, you're sort of

796
00:40:43,800 --> 00:40:46,200
Speaker 1: blowing the whole thing open, right, Like you're saying, now

797
00:40:46,200 --> 00:40:50,879
Speaker 1: you could pretty much imagine anything that could explain that change. Yeah,

798
00:40:50,920 --> 00:40:54,000
Speaker 1: although it's a bit more complicated, right, It's simpler to say, oh,

799
00:40:54,000 --> 00:40:56,360
Speaker 1: the universe has this new property, and that property is

800
00:40:56,400 --> 00:40:59,279
Speaker 1: a constant and it just is. It's more complicated to

801
00:40:59,280 --> 00:41:00,840
Speaker 1: come up with a new piece which you have to

802
00:41:00,880 --> 00:41:04,680
Speaker 1: explain and then also explain why it's no longer around.

803
00:41:04,800 --> 00:41:07,680
Speaker 1: It's just as tricky as inflation. Like with inflation, we

804
00:41:07,760 --> 00:41:10,200
Speaker 1: have this very rapid expansion of the early universe which

805
00:41:10,239 --> 00:41:12,680
Speaker 1: you have to explain. You also have to explain why

806
00:41:12,760 --> 00:41:16,080
Speaker 1: that stopped. And so early dark energy is a special

807
00:41:16,120 --> 00:41:18,560
Speaker 1: puzzle for theorists because they have to explain why it

808
00:41:18,560 --> 00:41:22,319
Speaker 1: exists and also why it no longer seems to exist. Right,

809
00:41:22,440 --> 00:41:24,320
Speaker 1: and they also have to get up early, which is

810
00:41:24,320 --> 00:41:27,160
Speaker 1: a big problem. Just stay up late enough, or drink

811
00:41:27,200 --> 00:41:29,399
Speaker 1: a lot of dark coffee. All right, Well, let's get

812
00:41:29,440 --> 00:41:32,920
Speaker 1: into whether this early dark energy is real and what

813
00:41:32,960 --> 00:41:35,920
Speaker 1: we're doing to measure it and or confirm all of

814
00:41:35,920 --> 00:41:39,600
Speaker 1: these dark Shenanigan ideas. But first let's take a quick break.

815
00:41:52,120 --> 00:41:54,760
Speaker 1: All right, we're talking about the mystery of dark energy,

816
00:41:54,920 --> 00:41:58,279
Speaker 1: which apparently, um, it's not this constant thing. It's sort

817
00:41:58,320 --> 00:42:00,239
Speaker 1: of this seems to be this kind of fickle saying

818
00:42:00,239 --> 00:42:02,680
Speaker 1: almost like it was pretty lazy at the beginning of

819
00:42:02,760 --> 00:42:05,920
Speaker 1: the universe after inflation, right, that's the idea. But now

820
00:42:05,960 --> 00:42:09,280
Speaker 1: it's sort of getting steam, and it's maybe getting darker

821
00:42:09,320 --> 00:42:13,040
Speaker 1: and later, and so it's getting more energy exactly. And

822
00:42:13,080 --> 00:42:15,640
Speaker 1: it's amazing to me that dark energy sort of ever worked.

823
00:42:15,960 --> 00:42:17,840
Speaker 1: You know, we look back now the history of the

824
00:42:17,920 --> 00:42:21,319
Speaker 1: universe's expansion and it's incredible that you can add this

825
00:42:21,640 --> 00:42:23,960
Speaker 1: simple term to just say, well, space seems to have

826
00:42:24,080 --> 00:42:27,480
Speaker 1: this weird potential energy in it, which Einstein's equations predict

827
00:42:27,560 --> 00:42:31,640
Speaker 1: cause this expansion, this repulsive force to stretch out the universe,

828
00:42:31,960 --> 00:42:35,680
Speaker 1: and that that mostly describes what we see after inflation.

829
00:42:35,719 --> 00:42:38,319
Speaker 1: We see this period of very slow expansion then sort

830
00:42:38,360 --> 00:42:41,080
Speaker 1: of picked up steam around eight or nine billion years

831
00:42:41,120 --> 00:42:44,400
Speaker 1: after the universe and is now accelerating very very quickly.

832
00:42:44,480 --> 00:42:47,680
Speaker 1: It's sort of amazing that that complex history can in

833
00:42:47,719 --> 00:42:51,680
Speaker 1: fact be described almost by a constant term. I think

834
00:42:51,719 --> 00:42:53,720
Speaker 1: that's pretty cool. I mean, the fact that it doesn't

835
00:42:53,840 --> 00:42:56,640
Speaker 1: quite work means, you know, it needs some new ideas,

836
00:42:56,640 --> 00:42:58,320
Speaker 1: but I think it's sort of awesome that it works

837
00:42:58,320 --> 00:43:00,319
Speaker 1: at all. Well, it's the only sort of sort of

838
00:43:00,360 --> 00:43:03,200
Speaker 1: works right, Like it could just be like totally wrong,

839
00:43:04,200 --> 00:43:07,160
Speaker 1: Like our whole sort of formulation of the universe could

840
00:43:07,200 --> 00:43:09,200
Speaker 1: be totally wrong, and this could be sort of like

841
00:43:09,239 --> 00:43:11,680
Speaker 1: the thing that makes us see that it's wrong, right exactly.

842
00:43:11,680 --> 00:43:13,440
Speaker 1: And that's why we do these studies in more and

843
00:43:13,480 --> 00:43:15,760
Speaker 1: more detail. You know, when you're first looking at something,

844
00:43:15,840 --> 00:43:18,040
Speaker 1: if you have like a simple explanation that sort of

845
00:43:18,120 --> 00:43:20,960
Speaker 1: mostly describes it, that's kind of cool. Like if you're

846
00:43:20,960 --> 00:43:23,560
Speaker 1: plotting to quantities that you've measured and they follow along

847
00:43:23,600 --> 00:43:26,319
Speaker 1: a straight line, you're like, that's interesting, and then as

848
00:43:26,320 --> 00:43:27,960
Speaker 1: you get more points, you're like, oh, it turns out

849
00:43:27,960 --> 00:43:30,600
Speaker 1: it's not quite a straight line, it's almost. Then you

850
00:43:30,640 --> 00:43:33,000
Speaker 1: know you need to refine your understanding, your theory. But

851
00:43:33,200 --> 00:43:35,719
Speaker 1: the fact that like mostly a straight line describes it,

852
00:43:35,680 --> 00:43:37,680
Speaker 1: it is already pretty powerful. Well, I think a big

853
00:43:37,760 --> 00:43:40,080
Speaker 1: question that you also rais is whether or not this

854
00:43:40,680 --> 00:43:45,200
Speaker 1: changing dark energy effect is actually real, because I think,

855
00:43:45,200 --> 00:43:47,439
Speaker 1: as you said, it's it's sort of based on two

856
00:43:47,520 --> 00:43:50,560
Speaker 1: very different kinds of measurements, right, Like we measure dark

857
00:43:50,680 --> 00:43:53,600
Speaker 1: energy now using one thing, but then early in the

858
00:43:53,680 --> 00:43:57,120
Speaker 1: universe we measure doing using something else. So like, you know,

859
00:43:57,360 --> 00:44:01,120
Speaker 1: like a ten percent difference using to totally different measurement

860
00:44:01,200 --> 00:44:05,759
Speaker 1: systems seems sort of reasonable. It does, depending on those uncertainties, right,

861
00:44:05,880 --> 00:44:08,440
Speaker 1: Each of these things are very different styles and measurement

862
00:44:08,520 --> 00:44:11,239
Speaker 1: and we do this on purpose because we're interested in

863
00:44:11,280 --> 00:44:14,080
Speaker 1: something deep and true in the universe, so we try

864
00:44:14,080 --> 00:44:16,000
Speaker 1: to get a handle on it in different ways to

865
00:44:16,080 --> 00:44:18,520
Speaker 1: make sure that we're not getting biased by one of

866
00:44:18,520 --> 00:44:22,040
Speaker 1: our measurement techniques. And these really are very very different measurements.

867
00:44:22,080 --> 00:44:25,879
Speaker 1: It's important to understand, like the early measurements are very indirect.

868
00:44:26,400 --> 00:44:27,799
Speaker 1: You know, what we do when we look at the

869
00:44:27,840 --> 00:44:31,120
Speaker 1: cosmic microwave background radiation is we don't actually see dark

870
00:44:31,280 --> 00:44:34,200
Speaker 1: energy directly. What we do is we measure like how

871
00:44:34,280 --> 00:44:37,399
Speaker 1: much dark matter was there, how much normal matter was there.

872
00:44:37,480 --> 00:44:39,399
Speaker 1: We can tell that because we can see those two

873
00:44:39,440 --> 00:44:43,600
Speaker 1: things sloshing around in the early universe plasma and creating

874
00:44:43,640 --> 00:44:47,520
Speaker 1: like weird sound waves. It's called bury on acoustic oscillation

875
00:44:47,560 --> 00:44:49,400
Speaker 1: that we talked about once on the podcast. And we

876
00:44:49,440 --> 00:44:52,799
Speaker 1: can also measure how much energy there was overall in

877
00:44:52,800 --> 00:44:56,080
Speaker 1: the universe, a measurement of the curvature of space back then.

878
00:44:56,520 --> 00:44:58,840
Speaker 1: So the measurement of dark energy from the early universe

879
00:44:59,120 --> 00:45:01,560
Speaker 1: is actually just a a traction. It says how much

880
00:45:01,640 --> 00:45:04,160
Speaker 1: energy was there in total? How much can we account for.

881
00:45:04,200 --> 00:45:06,960
Speaker 1: We're using dark matter and normal matter, the rest of

882
00:45:06,960 --> 00:45:09,160
Speaker 1: which we call dark energy, So it's sort of like,

883
00:45:09,560 --> 00:45:12,879
Speaker 1: just by subtraction we assume how much dark energy there

884
00:45:13,000 --> 00:45:16,200
Speaker 1: was back then. It's very indirect. Well, I guess, because

885
00:45:16,200 --> 00:45:18,440
Speaker 1: it's so indirect, it makes me kind of feel like

886
00:45:19,239 --> 00:45:22,040
Speaker 1: it's just kind of a big guess. I mean, you're

887
00:45:22,040 --> 00:45:24,200
Speaker 1: looking at this picture from the early universe and you're

888
00:45:24,239 --> 00:45:26,800
Speaker 1: trying to, you know, throw it out these little tiny

889
00:45:27,200 --> 00:45:30,200
Speaker 1: nuances in the ripples of it. In in you're sort

890
00:45:30,239 --> 00:45:33,879
Speaker 1: of assuming all these proportions about the universe. Like how

891
00:45:34,040 --> 00:45:36,920
Speaker 1: confident are physicists about these measurements. There's a lot of

892
00:45:36,960 --> 00:45:40,160
Speaker 1: debate about that because in order to extract from that

893
00:45:40,400 --> 00:45:43,600
Speaker 1: the measurement of dark energy, you've got to make some assumptions,

894
00:45:43,600 --> 00:45:45,920
Speaker 1: like this data comes from the Plank satellite, which is

895
00:45:45,920 --> 00:45:49,520
Speaker 1: an exceptional instrument, very high precision measurement of the cosmic

896
00:45:49,560 --> 00:45:53,360
Speaker 1: microwave background radiation like revolutionized cosmology. But in order to

897
00:45:53,360 --> 00:45:55,759
Speaker 1: interpret this stuff, you need to have some models in

898
00:45:55,800 --> 00:45:58,600
Speaker 1: your head that you're using to interpret this data. So

899
00:45:58,719 --> 00:46:00,479
Speaker 1: what people have been doing in the last two years

900
00:46:00,520 --> 00:46:04,320
Speaker 1: as this discrepancy has arisen between this measurement from Plank,

901
00:46:04,400 --> 00:46:06,879
Speaker 1: from the early data from the CNB and the late

902
00:46:06,920 --> 00:46:09,799
Speaker 1: measurements from the supernova is to try to revisit those

903
00:46:09,840 --> 00:46:12,239
Speaker 1: things and ask questions. It's like, is there another way

904
00:46:12,239 --> 00:46:14,759
Speaker 1: to interpret this data? Can we see it another way?

905
00:46:14,760 --> 00:46:16,719
Speaker 1: Are there assumptions that we're making that we can change

906
00:46:16,760 --> 00:46:19,759
Speaker 1: And they've tried like changing those assumptions and starting from

907
00:46:19,800 --> 00:46:23,480
Speaker 1: scratch and using other ideas, and the measurement is persistently

908
00:46:23,520 --> 00:46:26,160
Speaker 1: too small, like they've banged on it and banged on

909
00:46:26,239 --> 00:46:28,120
Speaker 1: it and banged on it some more, and it just

910
00:46:28,120 --> 00:46:31,280
Speaker 1: seems to be very consistent. So that's the early expansion

911
00:46:31,320 --> 00:46:33,880
Speaker 1: of the universe. What about the late expansion of the universe?

912
00:46:33,920 --> 00:46:35,799
Speaker 1: How are we measuring that one? So that we have

913
00:46:35,880 --> 00:46:39,200
Speaker 1: to find some way to measure distance in the current universe,

914
00:46:39,239 --> 00:46:41,800
Speaker 1: that's the key. We want to know how far away

915
00:46:41,800 --> 00:46:44,759
Speaker 1: things are and how fast are they moving away from us.

916
00:46:45,280 --> 00:46:47,680
Speaker 1: So in order to measure the velocity of a function

917
00:46:47,719 --> 00:46:50,280
Speaker 1: of time in the universe, we need to measure velocity

918
00:46:50,320 --> 00:46:53,319
Speaker 1: of the function of apparent distance. Because things that are

919
00:46:53,360 --> 00:46:55,880
Speaker 1: far away from us, we see them in the past. Right,

920
00:46:56,239 --> 00:46:59,040
Speaker 1: something that's a billion light years away, we're not seeing

921
00:46:59,120 --> 00:47:01,480
Speaker 1: light from it today. We're seeing life from a billion

922
00:47:01,560 --> 00:47:04,000
Speaker 1: years ago. So in order to understand the expansion the

923
00:47:04,040 --> 00:47:06,840
Speaker 1: universe over time, we need to understand the velocity of

924
00:47:06,840 --> 00:47:09,640
Speaker 1: the universe as a function of distance from us today.

925
00:47:09,640 --> 00:47:12,560
Speaker 1: It's really the same thing. And to measure those distances

926
00:47:12,680 --> 00:47:14,879
Speaker 1: is always very very tricky, because how can you tell

927
00:47:14,960 --> 00:47:17,560
Speaker 1: something that's really close by and dim or really far

928
00:47:17,600 --> 00:47:21,200
Speaker 1: away and bright. Right, You can't tell unless you know

929
00:47:21,360 --> 00:47:23,680
Speaker 1: how bright it's supposed to be. So the key to

930
00:47:23,760 --> 00:47:28,000
Speaker 1: all of these late time measurements are calibrations of how

931
00:47:28,040 --> 00:47:30,880
Speaker 1: far away things are. So we have things like type

932
00:47:30,920 --> 00:47:34,160
Speaker 1: one A supernova which blow up in a very predictable way.

933
00:47:34,280 --> 00:47:37,080
Speaker 1: We know basically how bright they should be. And they

934
00:47:37,120 --> 00:47:39,640
Speaker 1: have other ways to do this, like these sephids, these

935
00:47:39,760 --> 00:47:43,600
Speaker 1: variable stars where their pulsation is very closely connected to

936
00:47:43,719 --> 00:47:46,040
Speaker 1: how bright they are at their source. And people have

937
00:47:46,080 --> 00:47:48,719
Speaker 1: been really creative and finding other ways to measure this

938
00:47:48,760 --> 00:47:54,760
Speaker 1: expansion using other calibratable objects neutron star, gravitational waves, and quasars,

939
00:47:54,880 --> 00:47:58,360
Speaker 1: and this recent measurement about red giants, and all of

940
00:47:58,360 --> 00:48:01,640
Speaker 1: these things are uncertain, uncertain different ways, Like we don't

941
00:48:01,719 --> 00:48:05,200
Speaker 1: quite know our measurements of the sefids reliable. Are we

942
00:48:05,200 --> 00:48:07,439
Speaker 1: accounting for the amount of dust between us and those

943
00:48:07,440 --> 00:48:09,960
Speaker 1: stars correctly? That's why we try to do it in

944
00:48:09,960 --> 00:48:12,279
Speaker 1: several different ways. The amazing thing is that all these

945
00:48:12,280 --> 00:48:16,239
Speaker 1: different measurements using ways ours or supernova or sephids or

946
00:48:16,320 --> 00:48:18,920
Speaker 1: red giant stars that have a helium flash in a

947
00:48:19,000 --> 00:48:22,359
Speaker 1: very predictable way, they all mostly agree with each other,

948
00:48:22,800 --> 00:48:25,839
Speaker 1: and they all disagree with this early measurement. So it's

949
00:48:25,840 --> 00:48:28,959
Speaker 1: really compelling and fascinating. Right, But is there another way

950
00:48:29,000 --> 00:48:32,279
Speaker 1: I guess to kind of link the two measurements other

951
00:48:32,360 --> 00:48:34,440
Speaker 1: than this dark energy discrepancy? Do you know what I mean? Like,

952
00:48:34,480 --> 00:48:36,640
Speaker 1: if I measure something with one ruler and I measure

953
00:48:36,640 --> 00:48:39,799
Speaker 1: another thing with a different, totally different ruler way of

954
00:48:39,840 --> 00:48:43,239
Speaker 1: measuring things, and they disagree, I wouldn't necessarily say that

955
00:48:43,239 --> 00:48:45,600
Speaker 1: that's a whole new constpant in the universe. I like

956
00:48:45,680 --> 00:48:48,359
Speaker 1: try to find other ways to see that the two

957
00:48:48,480 --> 00:48:52,520
Speaker 1: rulers or the two measurement systems agree in other things, right, Yeah,

958
00:48:52,600 --> 00:48:54,560
Speaker 1: And that's what they haven't done by trying to come

959
00:48:54,640 --> 00:48:56,960
Speaker 1: up with essentially other rulers. They got their Type one

960
00:48:56,960 --> 00:49:00,879
Speaker 1: a supernova ruler, and their SEFID ruler and their tip

961
00:49:00,920 --> 00:49:03,360
Speaker 1: of the red giant branch ruler, and all these different

962
00:49:03,400 --> 00:49:06,160
Speaker 1: rulers all basically seem to agree with each other, and

963
00:49:06,160 --> 00:49:08,880
Speaker 1: they should all make sort of different kinds of mistakes

964
00:49:08,960 --> 00:49:11,680
Speaker 1: if they do make mistakes. So that's a clue that like,

965
00:49:12,000 --> 00:49:16,160
Speaker 1: maybe this is real. Maybe the universe really is expanding

966
00:49:16,200 --> 00:49:19,360
Speaker 1: in this surprising way, because we haven't found a problem

967
00:49:19,400 --> 00:49:21,720
Speaker 1: with any of these measurements, right, but have you tied

968
00:49:22,120 --> 00:49:25,919
Speaker 1: the early universe CMB measurements to things like the say,

969
00:49:25,960 --> 00:49:29,080
Speaker 1: facifits or the red giant measurements. The only way we

970
00:49:29,120 --> 00:49:31,640
Speaker 1: can tie them is by taking that measurement from the

971
00:49:31,640 --> 00:49:34,719
Speaker 1: early universe and using it to predict how fast things

972
00:49:34,719 --> 00:49:37,920
Speaker 1: should be accelerating today, and that's where the disagreement is.

973
00:49:38,160 --> 00:49:40,600
Speaker 1: So what we're trying to do is make other measurements

974
00:49:40,640 --> 00:49:43,239
Speaker 1: from the early universe. And there's some pretty exciting, very

975
00:49:43,320 --> 00:49:46,600
Speaker 1: recent results from a telescope in Chile called the Atacama

976
00:49:46,760 --> 00:49:50,640
Speaker 1: Cosmology Telescope that also looks at the CNB, but in

977
00:49:50,640 --> 00:49:53,480
Speaker 1: a way that's different from the Plank satellite, right, And

978
00:49:53,560 --> 00:49:56,319
Speaker 1: that sounds super exciting, But I guess maybe my question is,

979
00:49:56,440 --> 00:49:59,960
Speaker 1: and we like confirm these measurements or confirm our ability

980
00:50:00,000 --> 00:50:02,320
Speaker 1: to measure the expansion of the universe using the CMB

981
00:50:02,840 --> 00:50:06,120
Speaker 1: with other ways or other ways of measuring the expansion. Now,

982
00:50:06,400 --> 00:50:08,719
Speaker 1: like you're saying, the early universe expansion is measured by

983
00:50:08,800 --> 00:50:13,200
Speaker 1: the cosmic microwave background radiation CNB, but the current expansion

984
00:50:13,239 --> 00:50:16,080
Speaker 1: is measured in a totally different way, and they come

985
00:50:16,160 --> 00:50:20,399
Speaker 1: up with different numbers, which may be something about dark

986
00:50:20,520 --> 00:50:23,239
Speaker 1: energy that's changing, or it could just be maybe that

987
00:50:23,400 --> 00:50:27,080
Speaker 1: our two measurements are not quite linked together or calibrating. Yeah,

988
00:50:27,120 --> 00:50:29,880
Speaker 1: it could be an issue with calibration. We can't measure

989
00:50:29,920 --> 00:50:32,359
Speaker 1: the dark energy today the same way we can from

990
00:50:32,400 --> 00:50:35,799
Speaker 1: the CMB. Right, That measurement we could make because we

991
00:50:35,880 --> 00:50:38,120
Speaker 1: had this special window where we get this life from

992
00:50:38,120 --> 00:50:41,160
Speaker 1: the cosmic microwave background radiation. We can't make that same

993
00:50:41,239 --> 00:50:43,680
Speaker 1: kind of measurement today. That would be really awesome if

994
00:50:43,719 --> 00:50:46,520
Speaker 1: we had a late time CMB that we could use

995
00:50:46,560 --> 00:50:49,640
Speaker 1: to measure and compared to the early time CMB. That's

996
00:50:49,680 --> 00:50:52,720
Speaker 1: just not available. Right. The universe doesn't give you everything

997
00:50:52,719 --> 00:50:54,839
Speaker 1: you want. You just got to look around for opportunities

998
00:50:54,880 --> 00:50:57,480
Speaker 1: and and your understanding must be wrong right now. Yeah,

999
00:50:57,640 --> 00:50:59,560
Speaker 1: I mean, it's amazing that we can do any of

1000
00:50:59,560 --> 00:51:01,880
Speaker 1: these measurements at all, or that we have these amazing

1001
00:51:01,920 --> 00:51:05,880
Speaker 1: instruments to measure these expansion of the universe. Now, and

1002
00:51:05,960 --> 00:51:07,719
Speaker 1: before I guess, I'm just saying, I'm just trying to

1003
00:51:07,800 --> 00:51:10,120
Speaker 1: understand what it is that the mystery is. And it

1004
00:51:10,160 --> 00:51:14,279
Speaker 1: seems like there's a discrepancy, a difference between measuring the

1005
00:51:14,400 --> 00:51:17,760
Speaker 1: early expansion of the universe using the CMB and measuring

1006
00:51:17,800 --> 00:51:20,879
Speaker 1: the current expansion of the universe using you know, other

1007
00:51:20,960 --> 00:51:25,360
Speaker 1: methods like supernovas and and seffords and red giants and

1008
00:51:25,440 --> 00:51:28,080
Speaker 1: things like that. And you know, one possibility for this

1009
00:51:28,160 --> 00:51:30,920
Speaker 1: difference is that there is something weird about dark energy

1010
00:51:31,000 --> 00:51:34,520
Speaker 1: that's changing or I wonder another possibility, just to you know,

1011
00:51:34,640 --> 00:51:37,440
Speaker 1: give us some context, is that maybe these two ways

1012
00:51:37,480 --> 00:51:41,080
Speaker 1: of measuring the expansion of the universe are not quite calibrated, right, Yeah,

1013
00:51:41,120 --> 00:51:43,560
Speaker 1: exactly one of them could be wrong. They could both

1014
00:51:43,600 --> 00:51:47,720
Speaker 1: be wrong, exactly. And people are digging into the details

1015
00:51:47,760 --> 00:51:50,200
Speaker 1: of how these measurements were made to look for potential

1016
00:51:50,239 --> 00:51:53,520
Speaker 1: sources of error or bias that's why it's so valuable

1017
00:51:53,600 --> 00:51:55,960
Speaker 1: to measure these things in multiple different ways, because it

1018
00:51:56,040 --> 00:51:59,040
Speaker 1: checks your understanding and because they have different potential sources

1019
00:51:59,080 --> 00:52:02,120
Speaker 1: of uncertainty, right, you know, all affected by the same bias.

1020
00:52:02,280 --> 00:52:04,359
Speaker 1: And that's one reason why they built this telescope in Chile,

1021
00:52:04,560 --> 00:52:07,120
Speaker 1: because it has different sensitivity than plank and so it

1022
00:52:07,200 --> 00:52:11,080
Speaker 1: probes the cosmic microway background radiation in a slightly different way,

1023
00:52:11,239 --> 00:52:14,799
Speaker 1: which gives a different power to answer this question. Right, Yeah,

1024
00:52:14,880 --> 00:52:17,160
Speaker 1: I guess it's an ongoing work. But um, I guess

1025
00:52:17,200 --> 00:52:20,560
Speaker 1: assuming then that our early measurement of expansion and our

1026
00:52:20,640 --> 00:52:25,360
Speaker 1: lading measurement of expansion are both correct and the same

1027
00:52:25,520 --> 00:52:28,040
Speaker 1: and have the same sort of basis in reality, then

1028
00:52:28,160 --> 00:52:31,560
Speaker 1: that's a big deal. That means dark energy is changing, right,

1029
00:52:31,800 --> 00:52:34,160
Speaker 1: So it's not a constant thing, and it may even

1030
00:52:34,239 --> 00:52:37,240
Speaker 1: change in the future. It may change in the future. Yeah, exactly.

1031
00:52:37,320 --> 00:52:40,040
Speaker 1: It means that the story is more complicated than just

1032
00:52:40,320 --> 00:52:42,319
Speaker 1: you have one field which has some potential in it

1033
00:52:42,480 --> 00:52:45,120
Speaker 1: and it has this constant contribution per unit of space,

1034
00:52:45,200 --> 00:52:47,120
Speaker 1: which tells you this story of the expansion has to

1035
00:52:47,160 --> 00:52:50,080
Speaker 1: be more complicated than that. You need some like extra

1036
00:52:50,120 --> 00:52:52,319
Speaker 1: bitted gas in the early universe to get us going

1037
00:52:52,560 --> 00:52:55,239
Speaker 1: so that we are expanding as fast as we see today.

1038
00:52:55,320 --> 00:52:57,400
Speaker 1: And you're right, we don't understand what that is. We

1039
00:52:57,440 --> 00:52:59,360
Speaker 1: don't know if it will come back, like and some

1040
00:52:59,440 --> 00:53:02,160
Speaker 1: of these raw can roll theories like that early dark

1041
00:53:02,239 --> 00:53:05,359
Speaker 1: energy rolls away, but hey, it could rock back, you know.

1042
00:53:05,400 --> 00:53:09,040
Speaker 1: It could be that the future has more accelerated expansion,

1043
00:53:09,120 --> 00:53:11,879
Speaker 1: or that it could go the opposite directions somehow. What

1044
00:53:11,920 --> 00:53:13,960
Speaker 1: it really means is that we just don't know very

1045
00:53:14,040 --> 00:53:16,879
Speaker 1: much about the future of the universe. Right. We could

1046
00:53:16,880 --> 00:53:19,840
Speaker 1: be headed towards a heavy metal rock universe or a

1047
00:53:20,120 --> 00:53:24,479
Speaker 1: easy listening universe. One of the things that is really

1048
00:53:24,480 --> 00:53:26,680
Speaker 1: interesting for me is that these new measurements from this

1049
00:53:26,760 --> 00:53:31,040
Speaker 1: Chilean telescope, they support this idea of early dark energy.

1050
00:53:31,160 --> 00:53:34,040
Speaker 1: They measure the cosmic microwave background radiation in a different

1051
00:53:34,040 --> 00:53:36,760
Speaker 1: way than plunk like. The details are kind of technical,

1052
00:53:36,880 --> 00:53:39,880
Speaker 1: but you know, ground based telescopes always have different sensitivities

1053
00:53:39,960 --> 00:53:43,440
Speaker 1: than space satellites, and when they analyze their data they

1054
00:53:43,480 --> 00:53:47,120
Speaker 1: see something consistent with theories of early dark energy, Like

1055
00:53:47,160 --> 00:53:49,879
Speaker 1: their data are more consistent with their being early dark

1056
00:53:50,000 --> 00:53:52,799
Speaker 1: energy than with their not being early dark energy. So

1057
00:53:52,840 --> 00:53:55,359
Speaker 1: they sort of disagree with Plank a little bit. Wait,

1058
00:53:55,400 --> 00:53:58,319
Speaker 1: what do you mean? Did they disagree Plank? When they

1059
00:53:58,320 --> 00:54:01,080
Speaker 1: look at their data, they don't see any specific evidence

1060
00:54:01,120 --> 00:54:04,440
Speaker 1: for early dark energy. Early dark energy, if it existed,

1061
00:54:04,520 --> 00:54:07,160
Speaker 1: would be this like extra expansion of the universe just

1062
00:54:07,320 --> 00:54:10,600
Speaker 1: before the CNB plasma was formed, and it would change

1063
00:54:10,640 --> 00:54:13,200
Speaker 1: a little bit how those ripples look. And Plank doesn't

1064
00:54:13,239 --> 00:54:16,560
Speaker 1: see that. But this new telescope, the ACT in Chili,

1065
00:54:16,880 --> 00:54:19,920
Speaker 1: it does see some weird ripples in the CNB that

1066
00:54:20,000 --> 00:54:22,920
Speaker 1: seemed consistent with their being an extra bit of expansion

1067
00:54:23,120 --> 00:54:25,680
Speaker 1: just before that plasma recombined, and so it's sort of

1068
00:54:25,760 --> 00:54:28,800
Speaker 1: more consistent with their being early dark energy than with

1069
00:54:28,920 --> 00:54:31,520
Speaker 1: their not. It's like a three sigma effect in their data.

1070
00:54:31,920 --> 00:54:34,960
Speaker 1: M I see. So again, just kind of maybe confirming

1071
00:54:35,000 --> 00:54:38,759
Speaker 1: that dark energy has changed and may change in the future. Right,

1072
00:54:38,960 --> 00:54:41,880
Speaker 1: It's more consistent with this complicated story of dark energy

1073
00:54:42,000 --> 00:54:44,120
Speaker 1: than with the simple idea of dark energy just being

1074
00:54:44,120 --> 00:54:46,200
Speaker 1: a number. Right, But wait, I thought the same B

1075
00:54:46,320 --> 00:54:49,000
Speaker 1: also confirmed that, Yeah, the Plank measurements don't agree with

1076
00:54:49,080 --> 00:54:51,239
Speaker 1: the late time, but they also don't see evidence for

1077
00:54:51,239 --> 00:54:54,880
Speaker 1: early dark energy. These measurements agree with Plank about how

1078
00:54:54,920 --> 00:54:57,359
Speaker 1: much dark energy there was, but they also see this

1079
00:54:57,480 --> 00:55:00,520
Speaker 1: extra effect which seems consistent with early dark energy. So

1080
00:55:00,560 --> 00:55:03,160
Speaker 1: it's new telescope disagrees with Plank a little bit. Maybe

1081
00:55:03,200 --> 00:55:06,600
Speaker 1: you need earlier dark energy or mid mid to late

1082
00:55:06,640 --> 00:55:12,200
Speaker 1: morning dark energy, sparkly dark energy. Well, and I think

1083
00:55:12,440 --> 00:55:15,799
Speaker 1: all this again means that the future is unpredictable, right,

1084
00:55:15,840 --> 00:55:18,200
Speaker 1: I think I think that's kind of the bigger deal

1085
00:55:18,280 --> 00:55:20,920
Speaker 1: is that, you know, if dark energy was constant and

1086
00:55:21,000 --> 00:55:22,840
Speaker 1: just the number that wasn't changing, then we sort of

1087
00:55:22,880 --> 00:55:24,759
Speaker 1: know how what's gonna happen in the future, and we

1088
00:55:24,800 --> 00:55:26,640
Speaker 1: know how the universe is going to end. But if

1089
00:55:26,640 --> 00:55:29,520
Speaker 1: we don't, if it's something totally complicated and different, who

1090
00:55:29,560 --> 00:55:32,719
Speaker 1: knows what's gonna happen, right, it could turn off for example, Yeah,

1091
00:55:32,880 --> 00:55:34,640
Speaker 1: we don't know what's going to happen in the future.

1092
00:55:34,840 --> 00:55:38,280
Speaker 1: It also, I think it's super fascinating affects our vision

1093
00:55:38,400 --> 00:55:41,000
Speaker 1: of the past. You know, if the universe has been

1094
00:55:41,040 --> 00:55:44,520
Speaker 1: expanding more rapidly than we thought, that means that it's

1095
00:55:44,719 --> 00:55:47,200
Speaker 1: younger than we thought because it didn't take as much

1096
00:55:47,280 --> 00:55:51,399
Speaker 1: time to get this expansion happening as we thought it did.

1097
00:55:51,840 --> 00:55:54,360
Speaker 1: Because the foot was on the gas pedal more strongly

1098
00:55:54,680 --> 00:55:57,520
Speaker 1: than we thought it was. So concretely, it might mean

1099
00:55:57,560 --> 00:56:00,000
Speaker 1: that the universe is only twelve and a half billion

1100
00:56:00,160 --> 00:56:03,040
Speaker 1: years old, not thirteen point eight, right, So we might

1101
00:56:03,120 --> 00:56:06,000
Speaker 1: have just like deleted a billion and a half years

1102
00:56:06,040 --> 00:56:10,560
Speaker 1: of history. Boom, you're all younger, everybody. Yeah, well, we're

1103
00:56:10,560 --> 00:56:13,600
Speaker 1: not younger. We're definitely not getting younger. But maybe the

1104
00:56:13,680 --> 00:56:16,120
Speaker 1: universe is younger than we thought exactly. And so that

1105
00:56:16,200 --> 00:56:18,040
Speaker 1: just goes to show you how will we know about

1106
00:56:18,040 --> 00:56:20,399
Speaker 1: the future of the universe, and how will we really

1107
00:56:20,520 --> 00:56:23,760
Speaker 1: understand about its past? How this picture of the universe

1108
00:56:23,760 --> 00:56:27,040
Speaker 1: and its expansion is still a big question mark. Yeah,

1109
00:56:27,080 --> 00:56:29,960
Speaker 1: I mean it's still dark basically, right, dark energy is

1110
00:56:30,080 --> 00:56:33,920
Speaker 1: that it's dark. It's a mystery. It's definitely probably not

1111
00:56:34,000 --> 00:56:36,399
Speaker 1: a constant. Who knows what it could be, right, that's right.

1112
00:56:36,480 --> 00:56:39,120
Speaker 1: Dark history even more fun than drunk history. Yeah, it

1113
00:56:39,120 --> 00:56:41,960
Speaker 1: could be cartoonist um drawing crazy things in the universe.

1114
00:56:43,440 --> 00:56:45,200
Speaker 1: I hope that's our future as well. Yeah, and I

1115
00:56:45,239 --> 00:56:47,200
Speaker 1: think it just confirms my theory that, you know, staying

1116
00:56:47,239 --> 00:56:51,359
Speaker 1: up late keeps you young, right, it seems to work

1117
00:56:51,400 --> 00:56:54,239
Speaker 1: so far exactly. Let's keep taking measurements all right, We'll

1118
00:56:54,280 --> 00:56:57,080
Speaker 1: stay tuned as we learn more about dark energy and

1119
00:56:57,160 --> 00:56:59,920
Speaker 1: what it could mean for our history of the universe

1120
00:57:00,080 --> 00:57:03,560
Speaker 1: and also the future. Maybe somebody out there listening to

1121
00:57:03,640 --> 00:57:06,680
Speaker 1: this could be the person who discovers what's really going

1122
00:57:06,760 --> 00:57:10,320
Speaker 1: on with early or late or mid to late morning

1123
00:57:10,440 --> 00:57:14,680
Speaker 1: dark energy. There's certainly a whole lot left to discover,

1124
00:57:14,880 --> 00:57:16,600
Speaker 1: a lot of time for a dark energy cook to

1125
00:57:16,600 --> 00:57:18,720
Speaker 1: come in. Basically, you might not even have to stay

1126
00:57:18,800 --> 00:57:20,800
Speaker 1: up late to figure it out. Well, thanks for joining us.

1127
00:57:20,800 --> 00:57:30,800
Speaker 1: We hope you enjoyed that. See you next time. Thanks

1128
00:57:30,840 --> 00:57:33,480
Speaker 1: for listening, and remember that Daniel and Jorge Explain the

1129
00:57:33,560 --> 00:57:36,680
Speaker 1: Universe is a production of I Heart Radio. For more

1130
00:57:36,760 --> 00:57:40,120
Speaker 1: podcast For my heart Radio, visit the i heart Radio app,

1131
00:57:40,360 --> 00:57:43,840
Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.

1132
00:57:45,480 --> 00:57:49,600
Speaker 1: Yeah