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Speaker 1: Hey, okay, I'm confused about something in the Star Wars universe. Well,

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Speaker 1: I've seen those movies, which means I have a PhD

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Speaker 1: in them. That's how they give out PhDs, right yeah,

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Speaker 1: at Star Wars University. I think that's the only requirement

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Speaker 1: sw go wookies. So my confusion is the Star Wars

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Speaker 1: universe has humans in it, right, like people. Ah, well

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Speaker 1: that's never clear. You know, they look like humans, but

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Speaker 1: technically they're all aliens right there e t s extrat rest. Well,

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Speaker 1: they're definitely biological humans. But they also have like super

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Speaker 1: advanced technology, right like far future stuff. Yeah. Yeah, they

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Speaker 1: have war drives and spaceships and light sabers. But it

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Speaker 1: also says that it takes place a long, long time ago,

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Speaker 1: So like, is it the past or is it the

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Speaker 1: future with fancy technology? Yeah? Yeah, I know. That's the

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Speaker 1: beauty of Georgia. Lucas is opening line a long time

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Speaker 1: ago in a galaxy far far away. This is something

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Speaker 1: that happened a long time ago, that's happening right now,

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Speaker 1: or it's going to happen in the future. Maybe in

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Speaker 1: the future I'll finally understand it. You just need to

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Speaker 1: rewatch the movies a few times. Maybe it's time I

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Speaker 1: get a second PhD hi am or handmade cartoonists and

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Speaker 1: the co author frequently asked questions about the Universe. Hi,

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Speaker 1: I'm Daniel. I'm a particle physicist and a professor at

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Speaker 1: UC Irvine, and I'm not prepared to defend the physics

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Speaker 1: of Star Wars. There is physics in Star Wars. That's

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Speaker 1: the problem. There isn't that much, so we can't defend

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Speaker 1: it well. I think from the beginning they say it's

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Speaker 1: a fantasy. They never claim it's science. I think that's

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Speaker 1: how George Lucas conceived it. He always thought of it

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Speaker 1: as a fantasy. It's like fantasy plus Westerns in space.

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Speaker 1: Anything is better in space, right except breathing? I guess

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Speaker 1: I don't know. It's dessert better in space necessarily. If

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Speaker 1: it's ice cream, sure that's gonna stay less and cold,

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Speaker 1: isn't it. I've had astronaut ice cream. It doesn't compare.

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Speaker 1: Welcome to our podcast, Daniel and Jorge Explain the Universe,

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Speaker 1: a production of I Heart Radio, in which we think

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Speaker 1: that the mysteries out in space are actually quite delicious.

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Speaker 1: We take a deep sip of all of the questions

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Speaker 1: we have about the nature of the universe, the way

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Speaker 1: things work, the way things are, the way they come

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Speaker 1: together to make this universe that we can somehow amazingly

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Speaker 1: inexplicably analyze and understand with our tiny little brains. We

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Speaker 1: can cast our simple mathematical stories over them and try

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Speaker 1: to get some understanding for why things happen and how

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Speaker 1: things happen. That's right, It's an amazing universe. And we

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Speaker 1: like to use the Force here in this podcast to

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Speaker 1: understand things like forces in the universe and particles and

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Speaker 1: stars and galaxies and black holes, because one day we

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Speaker 1: might be able to get really up close to these

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Speaker 1: kinds of we use the force. Really, are you using

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Speaker 1: the Jedi mind trick on me right now? I'm using

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Speaker 1: the electromagnetic force that we're transmitting on That's true, we

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Speaker 1: are using forces, But I thought there was a big

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Speaker 1: difference between forces and the force. I mean, in the

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Speaker 1: Star Wars universe, they have the normal forces, right, they

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Speaker 1: also have the force. Mm. Well, we've always talked in

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Speaker 1: this podcast how there might be one unifying force to

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Speaker 1: the universe, right, so maybe there is the force. Do

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Speaker 1: we also discuss miny Chlorians, where it's a far too

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Speaker 1: controversial even for us. See that's an attempt to describe

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Speaker 1: the force in terms of a scientific explanation. Maybe that's

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Speaker 1: why it wasn't so popular that you mean the Star

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Speaker 1: Wars movies weren't popular the prequels. Man, Yes, there's a

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Speaker 1: lot of controversy there. Yeah, they only made three kajillion dollars. Yeah,

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Speaker 1: but it is an awesome universe, full of galaxies that

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Speaker 1: are far far away and lots of events that happened

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Speaker 1: a long long time ago. Because the universe has been

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Speaker 1: around for a pretty long time and hopefully it will

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Speaker 1: be around for quite a while longer. Maybe, But because

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Speaker 1: is that it is a physical universe. It is at

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Speaker 1: the mercy of forces. We think that forces in this

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Speaker 1: universe control the shape of everything we experience, from the

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Speaker 1: reason that you don't fall through your chair to the

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Speaker 1: reason you are held on the Earth and the Earth

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Speaker 1: orbits around the Sun. The very structure of the galaxy

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Speaker 1: and the large scale structure of the universe are determined

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Speaker 1: by forces. Wait wait, wait, are you saying gravity is

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Speaker 1: a force? Gravity is a fictitious force. Yes, absolutely, it's

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Speaker 1: a Star Wars force. It's the Star Wars of forces.

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Speaker 1: I always wonder how they can stand up in those

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Speaker 1: spaceships when they're out in space fiction. That's how they

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Speaker 1: can do it. But in our universe, forces do determine

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Speaker 1: the large scale structure of everything if you include gravity

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Speaker 1: on that list, and they control how the universe in

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Speaker 1: the past has turned into universe we see today, and

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Speaker 1: also they will determine the universe's future. That's right, because

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Speaker 1: as still an ever lasting as the universe may seem,

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Speaker 1: it's actually changing. It has been changing, and it will

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Speaker 1: keep on changing. Used to be super super diverse, small

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Speaker 1: or at least super super dense, and now it's much bigger,

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Speaker 1: and it might keep changing in the future. Yeah, it

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Speaker 1: can be difficult to sort of think on the time

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Speaker 1: scale of the universe. You're used to looking up in

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Speaker 1: the night sky and seeing it always be the same.

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Speaker 1: The stars are not disappearing, they're not changing, they're not dancing.

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Speaker 1: But we have learned in many situations that the universe,

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Speaker 1: or even just the Earth changes on time scales that

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Speaker 1: are well beyond what humans are used to thinking about.

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Speaker 1: Millions of years ago, the Earth looked quite different. Billions

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Speaker 1: of years ago, the Earth didn't even exist, and so

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Speaker 1: the universe itself is rapidly changing, and we don't know

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Speaker 1: if we are a significant fraction of the way through

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Speaker 1: the history of the universe, or if this is just

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Speaker 1: the first brief flash of a universe that will last

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Speaker 1: for trillions or quadrillions or quintillions of years. Are you

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Speaker 1: asking if the universe has peaked already? Exactly is it

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Speaker 1: time to buy or sell shares in the universe? Well,

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Speaker 1: I think by shares of the universe, you just won't

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Speaker 1: be alive, probably by time someone catches in the universe.

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Speaker 1: Who exactly can you sell your shares the universe too?

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Speaker 1: I suppose is there a market out there in the

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Speaker 1: multiverse stock market? Maybe you just enjoy the dividends. Life

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Speaker 1: is pretty good, right, life is pretty good. In fact,

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Speaker 1: I enjoy the universe. But I wonder how long this

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Speaker 1: situation will last. How long will we be able to

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Speaker 1: sit on a nice cozy rock toasting our toes by

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Speaker 1: the fire of a distant sun. Is this something which

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Speaker 1: will last for billions or trillions of years in our universe?

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Speaker 1: Or is it a brief moment of respite on this

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Speaker 1: resort we call Earth. Yeah, because the universe has been

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Speaker 1: changing and it will keep on changing, probably, and so

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Speaker 1: we can ask what does the future hold? Can we

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Speaker 1: predict what's going to happen to the universe and we

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Speaker 1: measure it, and how do we know that's what it's

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Speaker 1: gonna do? Are we better able to predict the future

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Speaker 1: of the universe than we are able to predict the

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Speaker 1: future of the stock market, for example? And so to

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Speaker 1: be on the podcast, we'll be asking the question what

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Speaker 1: is the Big Rip? As this related to anyone's pants, Daniel,

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Speaker 1: It's what happens if you eat too much astronaut ice

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Speaker 1: cream or you sit down to watch the Star Wars

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Speaker 1: movies one too many times. No, it's a fun speculative

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Speaker 1: idea about the potential future of the universe because we're

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Speaker 1: still developing our understanding of how the universe works and

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Speaker 1: what all the forces at play are, and there are

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Speaker 1: enormous gaps remaining in that understanding. There's a large set

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Speaker 1: of possible futures for the universe, and the Big Rip

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Speaker 1: is one of the craziest ones. Yeah. I think we've

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Speaker 1: talked a little bit in this podcast about the end

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Speaker 1: of the universe, right. We had Katie Mack here talked

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Speaker 1: about her book The end of everything, and she kind

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Speaker 1: of walked us through a couple of the possible scenarios

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Speaker 1: for the universe. Yeah, that was a lot of fun

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Speaker 1: and it's a great book folks should check out if

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Speaker 1: you're interested in cosmology and reading about depressing ways we

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Speaker 1: can all die. And we also talked in great depth

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Speaker 1: on the podcast about some of the forces that are

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Speaker 1: at play there and what we understand about them and

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Speaker 1: what we don't understand about how they are still shaping

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Speaker 1: our universe today. Now this is called the Big Rip.

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Speaker 1: Now our physicist gonna change the name a little bit

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Speaker 1: later on though, the bigger rip or the even larger,

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Speaker 1: the even bigger rip. I'm looking forward to the super

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Speaker 1: rip because then the rs blend together. The cosmic rip

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Speaker 1: would in the cosmic rip be a better name for it, yeah,

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Speaker 1: or the cosmic rift. But we do have a lot

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Speaker 1: of ideas about how the universe might evolve and what

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Speaker 1: might happen to it trillions of years into the future

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Speaker 1: or maybe billions of years into the future, and this

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Speaker 1: is one of those ideas, and it's pretty interesting. It's

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Speaker 1: one of maybe what like three or four possible things

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Speaker 1: that might happen to the universe. I think it's actually

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Speaker 1: an infinite spectrum of possible outcomes to the universe. So yeah,

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Speaker 1: this is one of those, right right, that's right. They

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Speaker 1: could be a big rip, a bigger rip, small rip,

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Speaker 1: a medium sized rip, a pocket size rip, and then

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Speaker 1: of course there's all the ideas we just can't anticipate

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Speaker 1: because we are just so clueless about how the universe works.

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Speaker 1: We've only understood recently pretty basic stuff about things that

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Speaker 1: are controlling the evolution of the universe, so we should

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Speaker 1: definitely avoid being too confident but even categorizing the amount

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Speaker 1: of our understanding. All right, So today we're going to

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Speaker 1: focus on one possible thing that might happen to the universe.

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Speaker 1: And so, as usual, we were wondering how many people

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Speaker 1: have thought about the big Rip or what it could be.

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Speaker 1: So thanks very much to everybody who answers these questions

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Speaker 1: for the podcast, and if you would like to parts

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Speaker 1: to pay for future episodes, please don't be shy. It's easy,

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Speaker 1: it's fun, it doesn't hurt at all, Just right to me.

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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 the

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Speaker 1: big rip is? Here's what people had to say. I

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Speaker 1: think the big Rip is one of the possible ways

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Speaker 1: the universe might end UM where something at the subatomic level,

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Speaker 1: basically the whole universe on rabbles on itself. And I

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Speaker 1: want to say it has something to do with anti matter.

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Speaker 1: Maybe this was disgust UM two, like a meeting UM

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Speaker 1: took place where a lot of known physicists We're talking

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Speaker 1: about how the universe might end and theories, and reportedly

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Speaker 1: UM at this meeting, bon Laborritos were or so I

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Speaker 1: think somehow it's linked to this meeting. So the Big

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Speaker 1: Rip is a scenario for the end of the universe

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Speaker 1: where basically space time expands so quickly that every particle,

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Speaker 1: every subparticle gets ripped apart from each other and basically

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Speaker 1: can never meet another because the distance between any one

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Speaker 1: and another it's expanding fast from the speed of light,

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Speaker 1: so it's not very fun. The big rip is when

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Speaker 1: the universe just rips itself apart because it doesn't have

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Speaker 1: enough mass for the gravity to crunch back in on itself.

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Speaker 1: The group is a theory that posits that at the

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Speaker 1: auto is the end of the universe UM, there would

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Speaker 1: be almost like an inflation that causes everything in the

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Speaker 1: universe to move further apart, but um at a rapid

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Speaker 1: rot almost like an explosion. I think, all right, some

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Speaker 1: pretty definitive answers here. It's when everything ripped apart. Yeah,

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Speaker 1: in that sense, you might say it's a well named

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Speaker 1: physics theory. Yeah, yeah, I'll get it to them. Oh well,

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Speaker 1: let's find out what it is first though, and see

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Speaker 1: if it's related to a banana barrito and ripping into

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Speaker 1: a banana bridle. I'm not sure where that comment was going.

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Speaker 1: It was like a burrito made out of banana peals?

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Speaker 1: Is that the reference? Yeah, I don't know. That's a

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Speaker 1: slippery slope there. To mess with a burrito wrappings. I

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Speaker 1: don't know if you're supposed to eat a banana barrito

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Speaker 1: or smoke it. That's actually not a bad idea to

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Speaker 1: put plantains inside of a burrito. I think you got

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Speaker 1: something here. Listener, Well, let's get into a Daniel step

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Speaker 1: us through what is the big rip? So the big

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Speaker 1: rip is sort of like a super accelerated version of

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Speaker 1: what we already think is happening to our universe. Current

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Speaker 1: accepted idea of the cosmology of the universe. Is that

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Speaker 1: the universe is expanding, and that that expansion is accelerating,

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Speaker 1: meaning things are getting further and further apart. New spaces

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Speaker 1: being created all the time, everywhere in the universe, and

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Speaker 1: that's happening faster and faster every year. So even our

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Speaker 1: current universe is sort of already tearing itself apart. An

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Speaker 1: expansion is happening, and it's happening faster and faster every year.

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Speaker 1: The Big Rip is like a super charged version of

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Speaker 1: that that's going to accelerate the acceleration of that expansion,

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Speaker 1: so that everything gets pulled apart to the tiniest bits

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Speaker 1: at the end of time. Right, that's something we only

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Speaker 1: learned about recently, right, maybe in the last hundred years,

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Speaker 1: that the universe is actually expanding, it's not sitting still. Yeah,

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Speaker 1: we learned about a hundred years ago that the universe

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Speaker 1: is not just like a bunch of stars floating in space.

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Speaker 1: Back before Edwin Hubble, in the beginning of the last century,

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Speaker 1: people thought the universe was just like one galaxy. There's

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Speaker 1: just a bunch of stars out there floating in space,

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Speaker 1: and it was the way it was and always had been,

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Speaker 1: and the most natural theory for the universe was that

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Speaker 1: it always had been that way, and it always would

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Speaker 1: be that way. It was just sort of like static

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Speaker 1: and constant. But then Hubble saw other galaxies super duper

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Speaker 1: far away. He identified smudges in the telescopes, not as

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Speaker 1: nebula in our galaxy, but actual separate galaxies far away,

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Speaker 1: and he was able to measure the velocity of those

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Speaker 1: galaxies to see they were all moving away from us.

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Speaker 1: So surprise, the prize the universe is actually expanding. Mm hmm,

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Speaker 1: super interesting. How did he measure that the galaxy super

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Speaker 1: moving away? You can measure the redshift of the light

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Speaker 1: from those galaxies, so it looks a little redder than

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Speaker 1: the life from our galaxy, Then you know it's moving

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Speaker 1: away from me. If it looked a little bluer, it

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Speaker 1: would mean that it was moving towards us. Things that

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Speaker 1: emit light and have a relative velocity, the frequency of

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Speaker 1: that light changes. It's a basic Doppler shift kind of effect,

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Speaker 1: and things that are moving away from us, the light

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Speaker 1: gets stretched out to make it redder. And Hubble was

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Speaker 1: also able to measure the distance to these things, so

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Speaker 1: he was able to show the things that are further

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Speaker 1: away are moving away from us faster than things that

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Speaker 1: are closer. Now that this makes sense with our sort

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Speaker 1: of like theories about the universe and the makeup of

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Speaker 1: it and what it could do, Like, what did Einstein

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Speaker 1: think of this? Now, this was really confusing to folks

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Speaker 1: like Einstein at the time. You know, before Einstein, we

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Speaker 1: had an idea of gravity as a force. Mass pulls

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Speaker 1: on other mass, stuffed tugs together gently. Right. Einstein in

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Speaker 1: up with this idea that actually gravity is not a force,

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Speaker 1: it's a curvature of the universe, that space itself is

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Speaker 1: bent by mass and energy, and that's why things tend

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Speaker 1: or sort of rolled together. The problem Einstein faced, even

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Speaker 1: before Hubble's realization, was that this predicted that the universe

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Speaker 1: would collapse, that all the mass and the energy and

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Speaker 1: the universe would sort of pull itself together and shrink

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Speaker 1: the universe. At the time, they thought the universe was static, right,

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Speaker 1: They thought that it was just sort of hanging out there.

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Speaker 1: So Einstein needed to invent something to balance the mass

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Speaker 1: pulling everything together. So he added a fudge factor to

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Speaker 1: his theory, something we now call the cosmological constant, which

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Speaker 1: we've given outwards pressure to balance all of the mass

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Speaker 1: coming in. So Einstein had this idea of a universe

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Speaker 1: sort of balanced on a knife edge, this outward pressure

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Speaker 1: providing exactly what you need to balance the inward pull

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Speaker 1: of all the mass. And then Hubble literally blew that

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Speaker 1: all up, right, because I guess if you imagine a

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Speaker 1: bunch of stuff just floating out there in space as

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Speaker 1: far as we knew back then, they should just all

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Speaker 1: come together because of ay, right, Like, if you put

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Speaker 1: two rocks out there in space, away from a lot

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Speaker 1: of other stuff, is that there two rucks are going

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Speaker 1: to attract each other and come together, right, And so

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Speaker 1: if you have a bunch of stars or a bunch

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Speaker 1: of planets out there in space, and the universe as

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Speaker 1: we saw it, it should have all sort of crunched

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Speaker 1: together by now, right. If things are just hanging out there,

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Speaker 1: they have no relative velocity to start with. You put

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Speaker 1: two rocks anywhere in the universe, they will tug on

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Speaker 1: each other, and you give them enough time, they will

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Speaker 1: come together. So Einstein was sort of like puzzled, like,

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Speaker 1: why does my theory predict that the universe should collapse

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Speaker 1: right into one giant black hole effectively? So he added

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Speaker 1: a fudge factor, could in the universe be sort of

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Speaker 1: like our Solar system, Like our Solar system is out

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Speaker 1: out there in space, but it's not collapsing, right, Things

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Speaker 1: are moving around in orbits. Yeah, there is something that's

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Speaker 1: keeping the Solar system from collapsing rapidly, which is angular momentum.

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Speaker 1: So the Earth, as you say, is in orbit around

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Speaker 1: the Sun, just doesn't immediately collapse into the Sun. That orbit, though,

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Speaker 1: will decay. You know, eventually the Earth will lose some

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Speaker 1: of that velocity because it's bumping into stuff and it's

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Speaker 1: really eating away energy and gravitational waves. So if you're

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Speaker 1: talking about like the really deep future, then in Einstein's picture,

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Speaker 1: eventually everything would collapse into a black hole. M But

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Speaker 1: why did Einstein feel like you needed to add a

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Speaker 1: fudge factor to make the universe static? Could in the

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Speaker 1: universe be on its way to crunching down into a

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Speaker 1: black hole? It could have been, and we didn't have

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Speaker 1: great measurements, but the sort of prevailing view of the

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Speaker 1: universe was that it was static. We didn't see anything moving,

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Speaker 1: We didn't have great measurements. That which just sort of

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Speaker 1: like the universe we thought we lived in. It looked static.

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Speaker 1: It looks static, and so Hubble, you use this really

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Speaker 1: cool observation by another astronomer, Henrietta Levitt, who discovered a

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Speaker 1: certain kind of star called sephids. These are a particular

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Speaker 1: kind of starring You can use a trick to tell

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Speaker 1: how far away they are just by looking at the

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Speaker 1: light from them. We have a whole episode about Ubble's discoveries.

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Speaker 1: But Hubble was the first one to really be able

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Speaker 1: to tell how far away things were, and so he

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Speaker 1: could measure these velocities and he could tell that there

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Speaker 1: was this trend that things further away we're moving away

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Speaker 1: from us faster and faster. So that was the first

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Speaker 1: clue that actually the universe is expanding. Yeah, that mustn't

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Speaker 1: blown people's minds. How do you think that was received,

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Speaker 1: that people believe Hubble at first, or were they like, no,

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Speaker 1: you're crazy. I think the results were pretty solid because

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Speaker 1: they were based on these sephids, which were pretty hard

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Speaker 1: to dispute. And you can verify sephids using other distance

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Speaker 1: metrics like parallax. For things that are close enough up,

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Speaker 1: you can actually tell how far away something is based

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Speaker 1: on how it wiggles in the sky as we go

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Speaker 1: around the Sun. So there were a bunch of sefords

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Speaker 1: that people could verify exactly how they work using other methods,

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Speaker 1: and so it was kind of hard to dispute. But

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Speaker 1: it did lead to a big puzzle. Right. People were like,

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Speaker 1: hold on a second, we don't really understand what's going on.

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Speaker 1: So then Einstein actually had bandoned the cosmological constant. He's like, well,

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Speaker 1: scratch that. If the universe is expanding, we don't need

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Speaker 1: the cosmological constant to resist the expansion. Things are just

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Speaker 1: already zooming away from each other faster than gravity could

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Speaker 1: otherwise pull them together. So the Einstein's fudge factor was

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Speaker 1: actually holding back the universe in a way in his view,

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Speaker 1: just by virtue of Einstein's equations, you're saying the universe

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Speaker 1: would expand. What you're saying, No, you're saying the opposite. Right.

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Speaker 1: Einstein's new view was like, all right, maybe mass is

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Speaker 1: pulling the universe together, but it was already expanding. The

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Speaker 1: sort of two different aspects to think about there. One

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Speaker 1: is the rate of the expansion and the other sort

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Speaker 1: of the acceleration. Mass tends to like slow down the

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Speaker 1: rate of the expansion. But Einstein figured it's already expanding

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Speaker 1: and expanding so fast that the mass doesn't have time

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Speaker 1: to slow it down. It's sort of like hitting the

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Speaker 1: brakes on a car that's already going super duper fast.

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Speaker 1: So then he decided you didn't need that fudge factor. Yeah,

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Speaker 1: he figured, look, the expansion is positive, maybe the acceleration

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Speaker 1: is negative. Maybe mass is pulling everything forward, but we

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Speaker 1: don't need the fudge factor the cosmological constant to explain

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Speaker 1: why the universe is expanding anymore. Or he said, we

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Speaker 1: don't need the fudge factor to explain why the universe

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Speaker 1: hasn't crunched down. Yes, exactly, that's more accurate, thank you,

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Speaker 1: because it's already like growing out of control, So you

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Speaker 1: don't need to explain why it's not crunching that because

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Speaker 1: it's on steroids the universe exactly. He invented the cosmological

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Speaker 1: constant to explain why we had a static universe, and

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Speaker 1: then we discovered, oh, the universe isn't static, it's expanding.

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Speaker 1: So he sort of tossed it in the bin and

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Speaker 1: apologized for it. Did it really well? Famously, he said

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Speaker 1: that he thought it was one of his biggest scientific blunders. Yeah,

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Speaker 1: that guy, I couldn't get anything right. I'd like to

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Speaker 1: see humility in our great geniuses, you know. All right, well,

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Speaker 1: let's talk about what could be causing this expansion and

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Speaker 1: whether or not it's going to stay the same or

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Speaker 1: maybe ripped the universe apart. But first, let's take a

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Speaker 1: quick break. Alright, we're talking about the big rip, and

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Speaker 1: so Daniel let it rip. So for a long time

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Speaker 1: we knew that the universe was expanding, that we didn't

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Speaker 1: really understand what had caused it to expand, and we

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Speaker 1: thought maybe that mass in the universe was going to

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Speaker 1: slow down that expansion, but we didn't understand like, is

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Speaker 1: there enough mass in the universe to slow that expansion

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Speaker 1: down eventually to zero and maybe bring it back to

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Speaker 1: a big crunch, or is there not enough mass in

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Speaker 1: the universe to slow down that expansion? Like a rock

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Speaker 1: that you throw from the moon that will just go

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Speaker 1: out forever, right, there's not enough mass on the moon

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Speaker 1: to pull that rock back. Maybe the universe was like

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Speaker 1: that and we just continue to drift further and further

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Speaker 1: apart if there wasn't enough mass in the universe. So

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Speaker 1: people wanted to know the answer to that question. They

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Speaker 1: wanted to know. Willie universe keep drifting apart forever, gradually

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Speaker 1: slower and slower, or will eventually it slowed down and

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Speaker 1: come back into a big crunch That was sort of

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Speaker 1: the big question around the mid nineties, right, Or is

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Speaker 1: there a big plot twist in the middle there that

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Speaker 1: will totally change what we thought we've been watching on

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Speaker 1: the show. So spoiler alert for those of you who've

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Speaker 1: been saving papers from the mid nineties and having gotten

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Speaker 1: to read them yet. People developed a new way to

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Speaker 1: measure distances to even further objects, to things much much

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Speaker 1: further away, using type one a supernova special kind of

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Speaker 1: explosion of stars that tends to happen in the same

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Speaker 1: way every time, so we know how bright it should be.

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Speaker 1: So we can tell just by looking at the curve

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Speaker 1: of those stars how far away they are. Then by

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Speaker 1: looking at the red shift of them, we can also

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Speaker 1: tell how fast things are moving away. And this let

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Speaker 1: us look even further back in time to see the

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Speaker 1: deeper history of the expansion of the universe, and we

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Speaker 1: hoped it could help us decide between these two options.

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Speaker 1: Is the universe going to eventually slow down into a

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Speaker 1: big crunch or is it going to keep drifting apart forever,

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Speaker 1: gradually slowing down but never stopping. Couldn't they guess at

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Speaker 1: the time. I mean, if we had an idea of

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Speaker 1: the expansion of the universe, wouldn't at the time you

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Speaker 1: just be able to, you know, figure out if you

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Speaker 1: had enough mass to bring everything back together. Yeah, But

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Speaker 1: the data we're not sufficient to distinguish those two things.

429
00:21:36,600 --> 00:21:39,040
Speaker 1: It's like, if you're tracking an asteroid in space, you

430
00:21:39,040 --> 00:21:41,320
Speaker 1: can give a much better prediction of its future if

431
00:21:41,320 --> 00:21:43,200
Speaker 1: you have more data points, if you can look further

432
00:21:43,240 --> 00:21:45,840
Speaker 1: back in time to understand its trajectory, you can nail

433
00:21:45,880 --> 00:21:47,680
Speaker 1: down its future. In the same way, we didn't have

434
00:21:47,800 --> 00:21:51,440
Speaker 1: enough data points to distinguish between these two scenarios until

435
00:21:51,520 --> 00:21:53,600
Speaker 1: we look much further back in time and give us

436
00:21:53,600 --> 00:21:56,920
Speaker 1: like a longer lever arm to understand the evolving history

437
00:21:56,920 --> 00:21:59,760
Speaker 1: of the universe. But I guess if all we had

438
00:22:00,080 --> 00:22:04,159
Speaker 1: is mass out there in the universe, then even if

439
00:22:04,200 --> 00:22:07,240
Speaker 1: the universe was expanding pretty fast, wouldn't it all eventually

440
00:22:07,280 --> 00:22:10,399
Speaker 1: come back down? Would in gravity eventually win? Gravity doesn't

441
00:22:10,400 --> 00:22:13,240
Speaker 1: always win over velocity. Like if you're on the surface

442
00:22:13,240 --> 00:22:15,359
Speaker 1: of the Moon and you throw a baseball fast enough,

443
00:22:15,720 --> 00:22:18,240
Speaker 1: it will leave it. We'll have enough kinetic energy to

444
00:22:18,480 --> 00:22:22,119
Speaker 1: overcome the potential energy of gravity, and it can't escape.

445
00:22:22,240 --> 00:22:24,159
Speaker 1: But if there's only the Moon and that rock in

446
00:22:24,240 --> 00:22:27,080
Speaker 1: the entire universe, wouldn't that rock eventually come back. No,

447
00:22:27,200 --> 00:22:30,119
Speaker 1: it's possible for it to escape the gravitational attraction of

448
00:22:30,160 --> 00:22:33,120
Speaker 1: the Moon. If you give it enough velocity, it will

449
00:22:33,160 --> 00:22:35,840
Speaker 1: lose some of that velocity because the gravitational pull of

450
00:22:35,880 --> 00:22:38,320
Speaker 1: the Moon. But as it gets further and further away,

451
00:22:38,400 --> 00:22:40,760
Speaker 1: that gravitational pull gets weaker and weaker, and so it

452
00:22:40,760 --> 00:22:43,520
Speaker 1: starts to lose velocity slower and slower, but it never

453
00:22:43,600 --> 00:22:46,880
Speaker 1: goes to zero. So eventually will feel it slow down,

454
00:22:46,880 --> 00:22:49,480
Speaker 1: wouldn't it. No, it's possible to have escape velocity, right,

455
00:22:49,480 --> 00:22:52,520
Speaker 1: That's what escape velocity is, having enough kinetic energy to

456
00:22:52,640 --> 00:22:55,520
Speaker 1: overcome the potential energy of the gravity of an object. Well,

457
00:22:55,600 --> 00:22:57,560
Speaker 1: you can escape gravi it until you maybe fall into

458
00:22:57,600 --> 00:23:01,199
Speaker 1: another potential gravity. Well, but it was just you in

459
00:23:01,240 --> 00:23:03,040
Speaker 1: the moon, Eventually you would come back to the Moon,

460
00:23:03,040 --> 00:23:04,840
Speaker 1: wouldn't you. If it's just you and the Moon and

461
00:23:04,880 --> 00:23:07,800
Speaker 1: you have enough velocity, you can escape it. Think about

462
00:23:07,800 --> 00:23:10,080
Speaker 1: it this way. Two particles moving in opposite directions in

463
00:23:10,119 --> 00:23:13,119
Speaker 1: the universe don't necessarily have to fall back together if

464
00:23:13,119 --> 00:23:15,679
Speaker 1: they have enough velocity, there's a threshold there where, if

465
00:23:15,720 --> 00:23:19,600
Speaker 1: they're moving fast enough, they overcome their gravitational attraction, even

466
00:23:19,640 --> 00:23:22,520
Speaker 1: given infinite time, even given infinite time. Yeah, that's the

467
00:23:22,600 --> 00:23:24,800
Speaker 1: definition of escape velocity. I mean, I can escape the

468
00:23:24,880 --> 00:23:27,040
Speaker 1: velocity of the Earth, but eventually I'll come back to

469
00:23:27,800 --> 00:23:30,639
Speaker 1: the Solar system. Right. One way to understand how you

470
00:23:30,680 --> 00:23:33,919
Speaker 1: can actually escape the gravity of an object is to

471
00:23:33,960 --> 00:23:37,600
Speaker 1: think about the reverse process of falling into the object.

472
00:23:37,680 --> 00:23:40,920
Speaker 1: So think of all starting like at rest, zero velocity,

473
00:23:41,080 --> 00:23:44,760
Speaker 1: super duper far away, basically infinity away. Now you're right

474
00:23:44,840 --> 00:23:47,399
Speaker 1: that the Moon will tug on it, and eventually it'll

475
00:23:47,400 --> 00:23:49,600
Speaker 1: fall onto the Moon, and it will hit the Moon

476
00:23:49,680 --> 00:23:53,440
Speaker 1: with a certain speed, not an infinite speed. That speed

477
00:23:53,480 --> 00:23:57,440
Speaker 1: represents basically the energy difference between being on the Moon

478
00:23:57,560 --> 00:24:01,080
Speaker 1: and being infinitely far away. So now instead, if you

479
00:24:01,160 --> 00:24:04,560
Speaker 1: throw the ball away from the Moon with that same speed,

480
00:24:04,800 --> 00:24:07,520
Speaker 1: than what happens, Well, it reverses the process and it

481
00:24:07,600 --> 00:24:10,239
Speaker 1: loses all that velocity as it moves away, but it

482
00:24:10,280 --> 00:24:13,639
Speaker 1: has just enough to get infinitely far away before it

483
00:24:13,680 --> 00:24:16,119
Speaker 1: comes to a stop. So what that means is that

484
00:24:16,160 --> 00:24:19,800
Speaker 1: it takes a finite amount of velocity to get infinitely

485
00:24:19,880 --> 00:24:22,639
Speaker 1: far from the Moon's surface, and the same thing is

486
00:24:22,640 --> 00:24:25,080
Speaker 1: true for any surface is just a different velocity. So

487
00:24:25,119 --> 00:24:27,439
Speaker 1: now what happens if you throw the ball from the

488
00:24:27,480 --> 00:24:31,280
Speaker 1: Moon's surface a little bit faster than the escape velocity,

489
00:24:31,400 --> 00:24:34,440
Speaker 1: then it basically gets to infinity and still has some

490
00:24:34,520 --> 00:24:38,200
Speaker 1: speed left over, so it's not falling back even after

491
00:24:38,359 --> 00:24:40,960
Speaker 1: infinite time. All right. So then we expanded our view

492
00:24:40,960 --> 00:24:43,000
Speaker 1: of the universe and we measured the expansion of things

493
00:24:43,000 --> 00:24:44,880
Speaker 1: that were really far away. And what do we find.

494
00:24:45,000 --> 00:24:46,760
Speaker 1: We found, as we look deeper into the history of

495
00:24:46,760 --> 00:24:49,119
Speaker 1: the universe that we can make more confident predictions of

496
00:24:49,119 --> 00:24:51,639
Speaker 1: the future. And what we found was really shocking. We

497
00:24:51,680 --> 00:24:55,080
Speaker 1: found that the expansion of the universe wasn't decreasing slowly

498
00:24:55,280 --> 00:24:58,080
Speaker 1: or quickly. It wasn't decreasing at all. In fact, it

499
00:24:58,160 --> 00:25:01,600
Speaker 1: was increasing. That is that more sometimes the expansion seemed

500
00:25:01,600 --> 00:25:04,359
Speaker 1: to be happening faster and faster. That means that the

501
00:25:04,359 --> 00:25:08,359
Speaker 1: expansion of the universe was accelerating rather than slowing down.

502
00:25:08,480 --> 00:25:11,600
Speaker 1: So Einstein's picture of the universe expanding and somehow mass

503
00:25:11,640 --> 00:25:14,480
Speaker 1: slowing that down was wrong. There was another piece. There

504
00:25:14,560 --> 00:25:18,200
Speaker 1: was something else that actually was pushing out on everything

505
00:25:18,280 --> 00:25:20,480
Speaker 1: in the universe, making it move away from each other

506
00:25:20,760 --> 00:25:24,200
Speaker 1: faster and faster every year. Interesting, So the universe wasn't

507
00:25:24,240 --> 00:25:27,399
Speaker 1: just expanding, it was expanding faster and faster. What if

508
00:25:27,440 --> 00:25:30,800
Speaker 1: that was alarming, or if it was just interesting, or

509
00:25:31,040 --> 00:25:33,040
Speaker 1: how interesting would have been to find out that the

510
00:25:33,119 --> 00:25:36,040
Speaker 1: universe was actually collapsing. I remember when this discovery happened.

511
00:25:36,280 --> 00:25:39,000
Speaker 1: I was starting grad school. It was a huge shock.

512
00:25:39,160 --> 00:25:41,960
Speaker 1: Everybody was stunned. Nobody expected this result. It was a

513
00:25:42,000 --> 00:25:44,760
Speaker 1: massive revelation. It's the kind of thing you always dream

514
00:25:44,800 --> 00:25:48,120
Speaker 1: about in science, seeing something out there which surprises everybody,

515
00:25:48,119 --> 00:25:51,160
Speaker 1: which completely changes the way you think about the universe,

516
00:25:51,560 --> 00:25:54,439
Speaker 1: Like those are the best moments in science. So we

517
00:25:54,440 --> 00:25:56,840
Speaker 1: were all shocked, but we also knew that it was

518
00:25:56,880 --> 00:25:58,720
Speaker 1: a far future thing, like it was not going to

519
00:25:58,880 --> 00:26:01,720
Speaker 1: change our lives tomorrow or next year, or even in

520
00:26:01,800 --> 00:26:04,840
Speaker 1: a billion years. We're talking about the very very deep

521
00:26:04,920 --> 00:26:07,480
Speaker 1: future of the universe, not prediction for whether or not

522
00:26:07,560 --> 00:26:09,639
Speaker 1: you shoually have a picnic tomorrow. Right, And so we

523
00:26:09,760 --> 00:26:12,040
Speaker 1: learned I guess that the universe wasn't just expanding in

524
00:26:12,119 --> 00:26:14,359
Speaker 1: like a coasting kind of way. It was actually like

525
00:26:14,400 --> 00:26:18,040
Speaker 1: somebody was hitting the accelerator pedal on it, which means

526
00:26:18,080 --> 00:26:20,840
Speaker 1: there must be some kind of force or energy making

527
00:26:20,880 --> 00:26:23,760
Speaker 1: this happen right exactly, And immediately people went back to

528
00:26:24,000 --> 00:26:28,800
Speaker 1: Einstein's great blunder. Remember, Einstein added his cosmological constant, his

529
00:26:28,920 --> 00:26:31,879
Speaker 1: little bit of energy to the universe to balance the

530
00:26:31,960 --> 00:26:34,160
Speaker 1: mass that he thought was going to collapse the universe.

531
00:26:34,200 --> 00:26:35,920
Speaker 1: And then he got rid of it when he discovered

532
00:26:35,920 --> 00:26:39,280
Speaker 1: the universe wasn't static. And then people revived it there like, well,

533
00:26:39,600 --> 00:26:42,560
Speaker 1: we kind of need something to push out on the universe.

534
00:26:42,880 --> 00:26:46,320
Speaker 1: This cosmological constant. You stick it into Einstein's equations, and

535
00:26:46,359 --> 00:26:49,440
Speaker 1: it does just that. Creates this negative pressure pushes out

536
00:26:49,520 --> 00:26:53,720
Speaker 1: on everything. It expands space as time goes on. So

537
00:26:53,800 --> 00:26:57,080
Speaker 1: people plug this into Einstein's equations just to describe what

538
00:26:57,160 --> 00:26:59,840
Speaker 1: they saw was happening out there in the universe. That

539
00:27:00,080 --> 00:27:03,000
Speaker 1: expansion was accelerating, as you said, instead of slowing down.

540
00:27:03,200 --> 00:27:05,399
Speaker 1: So he was a genius, right, He didn't have to

541
00:27:05,440 --> 00:27:10,160
Speaker 1: be a falsely modest history justified his genius nous exactly.

542
00:27:10,280 --> 00:27:13,040
Speaker 1: His equations were so powerful in general they can even

543
00:27:13,119 --> 00:27:16,240
Speaker 1: describe discoveries made after his death. Yeah, so they called

544
00:27:16,280 --> 00:27:20,520
Speaker 1: this mysterious or energy making the universe expand faster and faster.

545
00:27:20,560 --> 00:27:23,320
Speaker 1: They give it a name dark energy. Yeah, and dark

546
00:27:23,440 --> 00:27:26,879
Speaker 1: energy is really just our observation that the acceleration of

547
00:27:26,920 --> 00:27:31,160
Speaker 1: the universe is expanding. We can describe it using Einstein's equations.

548
00:27:31,160 --> 00:27:33,119
Speaker 1: If we plug a number in and we can measure

549
00:27:33,119 --> 00:27:34,800
Speaker 1: that number and figure out what number we have to

550
00:27:34,840 --> 00:27:38,680
Speaker 1: put into Einstein's equations. That doesn't mean we understand why

551
00:27:38,760 --> 00:27:43,280
Speaker 1: that number is there or what this mechanism is dark energy.

552
00:27:43,440 --> 00:27:45,639
Speaker 1: It's not like dark energy is a theory, a piece

553
00:27:45,640 --> 00:27:48,040
Speaker 1: of physics that we understand we can make predictions for.

554
00:27:48,400 --> 00:27:50,840
Speaker 1: It's really just sort of like a descriptive framework for

555
00:27:50,920 --> 00:27:53,680
Speaker 1: something we don't yet understand. Right. And the name comes

556
00:27:53,760 --> 00:27:56,600
Speaker 1: from to words dark and energy. And it's dark because

557
00:27:56,640 --> 00:27:58,600
Speaker 1: you can't see it, right, It's not like the universe

558
00:27:58,720 --> 00:28:01,480
Speaker 1: is glowing from this energy g and it's energy because

559
00:28:01,640 --> 00:28:05,240
Speaker 1: it's doing work, right. Yeah, you definitely can't see dark energy.

560
00:28:05,440 --> 00:28:08,000
Speaker 1: That's always nothing called it dark because it was mysterious,

561
00:28:08,000 --> 00:28:10,600
Speaker 1: something we had been missing, something we couldn't yet explain.

562
00:28:10,720 --> 00:28:13,480
Speaker 1: It was like a gap in our understanding. But yeah,

563
00:28:13,480 --> 00:28:15,920
Speaker 1: it is also technically invisible. You can't look at a

564
00:28:15,920 --> 00:28:18,320
Speaker 1: piece of space and see whether or not there's dark

565
00:28:18,440 --> 00:28:19,960
Speaker 1: energy in it. What do you think they named the

566
00:28:20,040 --> 00:28:23,240
Speaker 1: dark energy just for the it's mysterious sounding name, not

567
00:28:23,359 --> 00:28:25,919
Speaker 1: because it's invisible to the visible light. I think so,

568
00:28:26,000 --> 00:28:28,560
Speaker 1: for example, they are also theories of like dark gravity

569
00:28:29,040 --> 00:28:32,479
Speaker 1: gravity that we hadn't accounted for yet. I think in general,

570
00:28:32,640 --> 00:28:35,639
Speaker 1: dark is applied to like mysterious things in physics that

571
00:28:35,680 --> 00:28:39,320
Speaker 1: doesn't seem very scientific then it. I'm not going to

572
00:28:39,440 --> 00:28:41,960
Speaker 1: defend the name of dark energy. Well, it just so

573
00:28:42,040 --> 00:28:44,760
Speaker 1: happens that it's also invisible, right, which is which makes it,

574
00:28:44,800 --> 00:28:47,800
Speaker 1: either by coincidence or on purpose, a an app name

575
00:28:47,840 --> 00:28:49,600
Speaker 1: for it, I suppose. I mean, to me, dark would

576
00:28:49,640 --> 00:28:53,560
Speaker 1: describe something that's not invisible but black, like charcoal is dark.

577
00:28:53,640 --> 00:28:56,680
Speaker 1: It's not invisible the invisible man, it's not dark, right,

578
00:28:56,760 --> 00:28:59,280
Speaker 1: you can't see through him. So a more accurate name

579
00:28:59,320 --> 00:29:02,200
Speaker 1: would be like visible energy or invisible matter. To me,

580
00:29:02,320 --> 00:29:06,160
Speaker 1: dark is not a very visually descriptive name for it. Well,

581
00:29:06,400 --> 00:29:10,320
Speaker 1: darkened as in it's not glowing. Yeah, that's true. It's

582
00:29:10,360 --> 00:29:13,520
Speaker 1: definitely not glowing, and it's an energy because it's doing work.

583
00:29:13,640 --> 00:29:16,440
Speaker 1: I guess, But where is this energy coming from? I guess, Well,

584
00:29:16,440 --> 00:29:18,520
Speaker 1: that's the big question. We don't know where this energy

585
00:29:18,600 --> 00:29:21,480
Speaker 1: is coming from. Einstein's equations tell you what the sort

586
00:29:21,480 --> 00:29:25,280
Speaker 1: of shape of spaces and how it transforms, but as input,

587
00:29:25,320 --> 00:29:27,600
Speaker 1: they require you to describe the universe, to say how

588
00:29:27,680 --> 00:29:29,880
Speaker 1: much mass is there, how much radiation is there, and

589
00:29:29,960 --> 00:29:33,920
Speaker 1: also how much potential energy is there. So Newton said

590
00:29:33,920 --> 00:29:37,480
Speaker 1: gravity is only between massive objects. Einstein's generalization is to

591
00:29:37,480 --> 00:29:40,120
Speaker 1: say no, gravity comes not just from objects with mass,

592
00:29:40,240 --> 00:29:43,600
Speaker 1: but all forms of energy, including potential energy and potential

593
00:29:43,680 --> 00:29:47,960
Speaker 1: energy actually has the opposite effect gravitationally as mass does.

594
00:29:48,160 --> 00:29:51,120
Speaker 1: So things with potential energy form a negative pressure. They

595
00:29:51,120 --> 00:29:54,160
Speaker 1: can expand the universe, they can push things apart. So

596
00:29:54,160 --> 00:29:56,480
Speaker 1: in order to describe the expansion of the universe, you

597
00:29:56,520 --> 00:29:59,360
Speaker 1: have to have some fields with potential energy that fill

598
00:29:59,440 --> 00:30:02,760
Speaker 1: the universe, that give you enough energy to accelerate the

599
00:30:02,800 --> 00:30:05,920
Speaker 1: expansion of the universe super dramatically. So you're saying that

600
00:30:05,960 --> 00:30:09,680
Speaker 1: maybe the universe just by itself in a vacuum and nothingness,

601
00:30:09,760 --> 00:30:14,200
Speaker 1: just space itself, has this potential energy, right, which is

602
00:30:14,240 --> 00:30:17,120
Speaker 1: making things expand. But why is it called potential, Like,

603
00:30:17,200 --> 00:30:20,000
Speaker 1: what's its potential, like it has the potential to do work.

604
00:30:20,120 --> 00:30:22,920
Speaker 1: Or what potential energy is the energy of configuration, right,

605
00:30:23,000 --> 00:30:26,440
Speaker 1: like a book on a shelf has gravitational potential energy

606
00:30:26,760 --> 00:30:30,680
Speaker 1: rather than kinetic energy, and waves can also have potential energy.

607
00:30:30,680 --> 00:30:33,000
Speaker 1: If you have a guitar string, for example, and you

608
00:30:33,080 --> 00:30:35,320
Speaker 1: pull it out but you don't yet release it, then

609
00:30:35,320 --> 00:30:37,520
Speaker 1: the tension in that string is giving it a lot

610
00:30:37,520 --> 00:30:40,240
Speaker 1: of potential energy. When you release it, the string that

611
00:30:40,480 --> 00:30:43,240
Speaker 1: vibrates it turns into kinetic energy, but that energy is

612
00:30:43,240 --> 00:30:46,160
Speaker 1: slashing back and forth between potential and kinetic as the

613
00:30:46,200 --> 00:30:49,400
Speaker 1: string vibrates. And quantum fields are the same way. The

614
00:30:49,440 --> 00:30:53,040
Speaker 1: fields that we think fills space can either oscillate with

615
00:30:53,120 --> 00:30:55,840
Speaker 1: kinetic energy and those are particles, or they can have

616
00:30:55,920 --> 00:30:59,720
Speaker 1: potential energy because of their configuration. For example, the Higgs

617
00:30:59,800 --> 00:31:03,040
Speaker 1: view we think has energy stored inside of it even

618
00:31:03,080 --> 00:31:06,120
Speaker 1: when it's not wiggling, sort of like stuck on this shelf,

619
00:31:06,360 --> 00:31:08,600
Speaker 1: it has a bunch of energy stored inside of it

620
00:31:08,720 --> 00:31:11,560
Speaker 1: just because of its configuration M and so we think

621
00:31:11,600 --> 00:31:14,400
Speaker 1: that's what dark energy is. It's some kind of potential

622
00:31:14,520 --> 00:31:17,840
Speaker 1: energy that the universe has, or that space has. We

623
00:31:17,840 --> 00:31:20,120
Speaker 1: know that space has some potential energy because of these

624
00:31:20,200 --> 00:31:22,720
Speaker 1: quantum fields. We think the quantum fields are real, We

625
00:31:22,760 --> 00:31:24,960
Speaker 1: think they have potential energy. We think all of space

626
00:31:25,000 --> 00:31:28,320
Speaker 1: really does have some potential energy. We also observe that

627
00:31:28,400 --> 00:31:31,720
Speaker 1: the universe is expanding, as if there is some potential

628
00:31:31,800 --> 00:31:35,400
Speaker 1: energy causing this gravitational repulsion. We try to bring these

629
00:31:35,400 --> 00:31:37,840
Speaker 1: two ideas together and say, is our estimate of the

630
00:31:37,840 --> 00:31:40,640
Speaker 1: amount of potential energy we already know exists in space

631
00:31:40,920 --> 00:31:43,880
Speaker 1: enough to describe this repulsion we see in the universe,

632
00:31:43,920 --> 00:31:47,160
Speaker 1: this expansion of the universe. People do that calculation, but

633
00:31:47,200 --> 00:31:50,400
Speaker 1: those two numbers do not agree. In fact, they disagree

634
00:31:50,720 --> 00:31:53,160
Speaker 1: by more than ten to the one hundred. So we

635
00:31:53,280 --> 00:31:56,120
Speaker 1: don't have an understanding of where the potential energy comes

636
00:31:56,200 --> 00:31:59,200
Speaker 1: from to create the expansion that we see in space.

637
00:31:59,640 --> 00:32:01,719
Speaker 1: We know the space has some potential energy in it,

638
00:32:01,920 --> 00:32:04,200
Speaker 1: it doesn't seem to have the right amount of potential

639
00:32:04,280 --> 00:32:07,080
Speaker 1: energy to cause the expansion we see out there in

640
00:32:07,120 --> 00:32:09,480
Speaker 1: the universe. You mean from a quantum field, we can

641
00:32:09,480 --> 00:32:11,760
Speaker 1: measure how much potential energy there has to be in

642
00:32:11,920 --> 00:32:14,200
Speaker 1: order to create this expansion, and then we can calculate

643
00:32:14,200 --> 00:32:16,240
Speaker 1: how much potential energy we think there is from the

644
00:32:16,320 --> 00:32:19,800
Speaker 1: quantum fields and those two numbers disagree by ten to

645
00:32:19,840 --> 00:32:21,719
Speaker 1: the one hundred. Well, at least you can't explain it

646
00:32:21,720 --> 00:32:24,600
Speaker 1: with the quantum fields that you know about, right exactly?

647
00:32:24,720 --> 00:32:27,360
Speaker 1: Could there be another quantum field or something or something

648
00:32:27,400 --> 00:32:30,600
Speaker 1: you're not seeing we're thinking about. Absolutely, there can be.

649
00:32:30,720 --> 00:32:33,200
Speaker 1: There has to be. There has to be some other explanation.

650
00:32:33,440 --> 00:32:35,840
Speaker 1: The point is just that we observe some expansion. We

651
00:32:35,880 --> 00:32:37,720
Speaker 1: think it might be due to some potential energy, but

652
00:32:37,760 --> 00:32:40,760
Speaker 1: we really do not have any understanding of the mechanism

653
00:32:41,160 --> 00:32:44,920
Speaker 1: for that potential energy to exist in the universe. All right, Well,

654
00:32:45,040 --> 00:32:47,880
Speaker 1: let's then assume there is some sort of potential energy

655
00:32:47,960 --> 00:32:50,560
Speaker 1: hidden in the universe, and there's quite a lot of it, right,

656
00:32:50,560 --> 00:32:53,800
Speaker 1: because it's making the universe expand faster and faster. But

657
00:32:53,920 --> 00:32:56,360
Speaker 1: it's just it's it's one of those things that only

658
00:32:57,000 --> 00:32:59,800
Speaker 1: you can only tell from over the whole universe, right,

659
00:33:00,080 --> 00:33:02,360
Speaker 1: can't tell, like looking at your hand in front of you,

660
00:33:02,600 --> 00:33:04,720
Speaker 1: that there is dark energy between you and your hand,

661
00:33:04,720 --> 00:33:07,000
Speaker 1: although there is dark energy between you and your hand,

662
00:33:07,080 --> 00:33:09,880
Speaker 1: that's right. Something people are often confused about is why

663
00:33:09,960 --> 00:33:13,400
Speaker 1: this expansion seems to be happening only between galaxies or

664
00:33:13,400 --> 00:33:16,320
Speaker 1: clusters of galaxies and not between you and your friend

665
00:33:16,720 --> 00:33:19,040
Speaker 1: or you and your lunch. And the answer is that

666
00:33:19,080 --> 00:33:22,479
Speaker 1: it is happening everywhere. All of space is expanding. The

667
00:33:22,520 --> 00:33:24,680
Speaker 1: distance between us and the Moon, and the distance between

668
00:33:24,760 --> 00:33:28,200
Speaker 1: us and the Sun. All of space is expanding simultaneously

669
00:33:28,240 --> 00:33:30,600
Speaker 1: at the same rate, all the time. It's actually a

670
00:33:30,680 --> 00:33:34,080
Speaker 1: very very small amount of expansion over many millions of

671
00:33:34,160 --> 00:33:37,920
Speaker 1: light years. Every second space grows by like a seventy kilometers.

672
00:33:38,160 --> 00:33:42,200
Speaker 1: It's a tiny, tiny level of expansion over short distances.

673
00:33:42,480 --> 00:33:44,880
Speaker 1: And over short distances like between me and my chair

674
00:33:45,040 --> 00:33:47,800
Speaker 1: or between the Earth and the Sun, other forces are

675
00:33:47,840 --> 00:33:50,960
Speaker 1: more powerful. So, for example, the Sun is powerful enough

676
00:33:51,000 --> 00:33:53,600
Speaker 1: to hold the Earth in its orbit even if space

677
00:33:53,680 --> 00:33:57,520
Speaker 1: is very gently expanding between it. But over very long distances,

678
00:33:57,600 --> 00:34:00,000
Speaker 1: like between galaxies, gravity gets very very weak, and dark

679
00:34:00,160 --> 00:34:03,800
Speaker 1: energy gets very very powerful, and so over those bigger distances,

680
00:34:03,920 --> 00:34:07,400
Speaker 1: dark energy winds. So in our current understanding of the universe,

681
00:34:07,440 --> 00:34:10,040
Speaker 1: dark energy is only effective at pushing apart things that

682
00:34:10,040 --> 00:34:12,920
Speaker 1: are very very far away from each other, like galaxies,

683
00:34:13,239 --> 00:34:16,120
Speaker 1: not things that are closer together like you and your lunch. Well,

684
00:34:16,160 --> 00:34:18,240
Speaker 1: it's more noticeable for things that are really far apart,

685
00:34:18,320 --> 00:34:21,440
Speaker 1: like galaxies, but it is sort of affecting our orbit

686
00:34:21,520 --> 00:34:23,799
Speaker 1: with the Sun, right Like, it's making it just a

687
00:34:23,840 --> 00:34:25,960
Speaker 1: little bit harder for the Sun to keep the Earth

688
00:34:25,960 --> 00:34:27,600
Speaker 1: in its orbit, and in a way, it's sort of

689
00:34:27,600 --> 00:34:31,080
Speaker 1: helping the Earth from collapsing into the Sun a little bit. Yeah,

690
00:34:31,120 --> 00:34:34,279
Speaker 1: it definitely plays a role, almost negligible, but yeah, not quite.

691
00:34:34,480 --> 00:34:37,400
Speaker 1: Universe would be a little bit different if that didn't happen.

692
00:34:37,480 --> 00:34:40,040
Speaker 1: All right, Well, I think the assumption so far is

693
00:34:40,040 --> 00:34:42,960
Speaker 1: that this dark energy is constant, that it's sort of

694
00:34:43,000 --> 00:34:45,359
Speaker 1: like there as a feature of the universe, and it's

695
00:34:45,400 --> 00:34:47,759
Speaker 1: always been there and maybe always will be there. But

696
00:34:47,880 --> 00:34:50,080
Speaker 1: the question is what if it's not. What if dark

697
00:34:50,200 --> 00:34:53,000
Speaker 1: energy changes? What if it decides that it wants to

698
00:34:53,080 --> 00:34:55,200
Speaker 1: join the dark side? And so let's get into what

699
00:34:55,280 --> 00:34:57,840
Speaker 1: might happen. But far ast, let's take another quick break.

700
00:35:10,520 --> 00:35:13,200
Speaker 1: All right, we're talking about the Big rip now, Daniel.

701
00:35:13,239 --> 00:35:15,640
Speaker 1: Is that what happens when the mind Cloreans decide to

702
00:35:15,680 --> 00:35:18,279
Speaker 1: go on strike and the whole universe falls apart. No,

703
00:35:18,440 --> 00:35:20,440
Speaker 1: that's when Disney by Star Wars and puts out a

704
00:35:20,440 --> 00:35:22,680
Speaker 1: bunch of low quality stuff. It's called the Big rip Off.

705
00:35:24,040 --> 00:35:27,120
Speaker 1: Not a fan huh of the new stuff? Why did

706
00:35:27,200 --> 00:35:29,720
Speaker 1: you just join the Star Trek camp while you're added.

707
00:35:29,840 --> 00:35:32,480
Speaker 1: I'm in both camps. I love Star Wars and Star Trek.

708
00:35:32,640 --> 00:35:35,520
Speaker 1: You just like stars do? I do like Stars Intact

709
00:35:35,560 --> 00:35:38,719
Speaker 1: anything with stars and sip almost anything. Yeah, but have

710
00:35:38,800 --> 00:35:42,240
Speaker 1: you seen and or Daniel? I have seen it? Yeah,

711
00:35:42,280 --> 00:35:45,920
Speaker 1: all right, I'm guessing your silence means that I'm not

712
00:35:46,040 --> 00:35:48,440
Speaker 1: a fan either. I like to say positive or silent

713
00:35:48,520 --> 00:35:51,200
Speaker 1: on the podcast. All right, Well, we're talking about the

714
00:35:51,239 --> 00:35:53,560
Speaker 1: Big Rip, which is a possible thing that might happen

715
00:35:53,600 --> 00:35:56,480
Speaker 1: to the universe, and it's related to a dark energy

716
00:35:56,560 --> 00:36:00,439
Speaker 1: which is making the universe expand faster and faster now.

717
00:36:01,200 --> 00:36:03,839
Speaker 1: But the universe hasn't always been expanding at the same

718
00:36:03,960 --> 00:36:06,120
Speaker 1: rate in its history, right, Yeah, the history of the

719
00:36:06,120 --> 00:36:08,799
Speaker 1: expansion the universe is quite complicated. We have some very

720
00:36:08,920 --> 00:36:11,960
Speaker 1: rapid expansion early on that we call inflation. Is sort

721
00:36:12,000 --> 00:36:14,560
Speaker 1: of like the last stages of the Big Bang, when

722
00:36:14,600 --> 00:36:18,120
Speaker 1: things expanded like by a factor tended the thirty intended

723
00:36:18,160 --> 00:36:20,920
Speaker 1: the minus thirty seconds. And then for a while the

724
00:36:21,000 --> 00:36:24,920
Speaker 1: universe was matter and radiation dominated. So the expansion was

725
00:36:24,960 --> 00:36:28,200
Speaker 1: still happening, but it was decelerating. It was slowing down

726
00:36:28,280 --> 00:36:31,920
Speaker 1: a bit. But dark energy was quietly building, and around

727
00:36:32,040 --> 00:36:35,840
Speaker 1: five billion years ago dark energy became the dominant component

728
00:36:36,040 --> 00:36:39,640
Speaker 1: of the universe and that's when the acceleration really took off.

729
00:36:40,160 --> 00:36:42,719
Speaker 1: And so the last five billion years, the expansion has

730
00:36:42,760 --> 00:36:45,600
Speaker 1: been accelerating. Now, when you say the dark energy kind

731
00:36:45,640 --> 00:36:48,239
Speaker 1: of agreed, did it actually grow or is it just

732
00:36:48,360 --> 00:36:51,600
Speaker 1: that the universe got bigger. What's the difference between those two, Well,

733
00:36:51,640 --> 00:36:53,680
Speaker 1: like for the same size universe, if the universe had

734
00:36:53,680 --> 00:36:55,600
Speaker 1: been the same size, what are you saying that dark

735
00:36:55,719 --> 00:36:59,160
Speaker 1: energy got stronger in the meantime or did it just

736
00:36:59,200 --> 00:37:01,440
Speaker 1: get more powerful because the universe is at bigger and

737
00:37:01,520 --> 00:37:04,240
Speaker 1: dark energy gets bigger the bigger spaces. Now, the current

738
00:37:04,239 --> 00:37:06,960
Speaker 1: theory is that dark energy is constant, that in a

739
00:37:07,000 --> 00:37:08,719
Speaker 1: certain amount of space you have a certain amount of

740
00:37:08,760 --> 00:37:12,239
Speaker 1: potential energy and that doesn't change. So dark energy, we think,

741
00:37:12,320 --> 00:37:15,960
Speaker 1: is a constant strength through time. But we do think

742
00:37:16,040 --> 00:37:19,000
Speaker 1: that the universe is expanding and is making new space

743
00:37:19,320 --> 00:37:22,800
Speaker 1: and therefore making more dark energy. Most of the stuff

744
00:37:22,800 --> 00:37:25,880
Speaker 1: in the universe dilutes as space gets bigger, Like you

745
00:37:25,880 --> 00:37:27,600
Speaker 1: have a certain amount of mass in the universe and

746
00:37:27,640 --> 00:37:30,920
Speaker 1: then things expand then the mass gets less dense. Dark

747
00:37:31,040 --> 00:37:34,160
Speaker 1: energy doesn't get less dense as the universe expands, because

748
00:37:34,200 --> 00:37:37,920
Speaker 1: it's an aspect of space itself. It's like inherent in space,

749
00:37:38,120 --> 00:37:42,080
Speaker 1: and so as the universe expands, dark energy doesn't shrink,

750
00:37:42,280 --> 00:37:45,200
Speaker 1: and so proportionately it grows to be a larger fraction

751
00:37:45,280 --> 00:37:47,520
Speaker 1: of the energy budget of the universe. So when you

752
00:37:47,560 --> 00:37:50,600
Speaker 1: say that the universe like it inflated really rapidly, then

753
00:37:50,600 --> 00:37:53,000
Speaker 1: it slowed down, then it picked back up again, that's

754
00:37:53,000 --> 00:37:57,360
Speaker 1: still consistent with a constant dark energy. But is that

755
00:37:57,440 --> 00:38:00,640
Speaker 1: only because you're assigning the accelerat a shan to slow

756
00:38:00,680 --> 00:38:02,960
Speaker 1: down to other things that you also don't know what

757
00:38:03,040 --> 00:38:04,799
Speaker 1: they are. Well, we think we know if the rest

758
00:38:04,800 --> 00:38:06,839
Speaker 1: of the universe is right. We think there's normal matter,

759
00:38:06,960 --> 00:38:09,400
Speaker 1: there's some radiation. We think there's a lot of dark matter.

760
00:38:09,760 --> 00:38:12,040
Speaker 1: We don't know exactly what dark matter is made out of,

761
00:38:12,239 --> 00:38:14,160
Speaker 1: but we have a pretty good sense of how much

762
00:38:14,200 --> 00:38:16,200
Speaker 1: of it there is and where it was and how

763
00:38:16,239 --> 00:38:18,880
Speaker 1: it controlled the large scale structure of the universe. But

764
00:38:18,920 --> 00:38:21,399
Speaker 1: in order to describe the expansion history that we see,

765
00:38:21,760 --> 00:38:23,920
Speaker 1: you need to plug in a certain amount of energy

766
00:38:24,000 --> 00:38:26,560
Speaker 1: per unit of space, and then it actually describes the

767
00:38:26,640 --> 00:38:28,960
Speaker 1: history quite nicely. But we still don't know what costs

768
00:38:29,000 --> 00:38:31,399
Speaker 1: in the initial inflation, right, the big bank. That could

769
00:38:31,400 --> 00:38:34,279
Speaker 1: have been also dark energy, but instead you're assigning it

770
00:38:34,320 --> 00:38:36,279
Speaker 1: to something else, right, I see, Yes, And there's still

771
00:38:36,320 --> 00:38:39,360
Speaker 1: a lot of confusion about what happened early on. The

772
00:38:39,400 --> 00:38:41,719
Speaker 1: current theory is that inflation may have been due to

773
00:38:41,800 --> 00:38:44,440
Speaker 1: some other field with a lot of potential energy, like

774
00:38:44,480 --> 00:38:47,839
Speaker 1: the inflaton field, because that expansion was quite different from

775
00:38:47,880 --> 00:38:50,480
Speaker 1: the expansion we're seeing now, different and just the rate

776
00:38:50,719 --> 00:38:53,279
Speaker 1: or different in the nature of it. Definitely different in

777
00:38:53,320 --> 00:38:56,560
Speaker 1: the rate, possibly also different in the nature. It could

778
00:38:56,560 --> 00:39:00,000
Speaker 1: have been a different field providing potential energy to create

779
00:39:00,000 --> 00:39:03,040
Speaker 1: at that expansion. We just don't know, huge question. Or

780
00:39:03,200 --> 00:39:05,000
Speaker 1: or it could have been dark energy to right, Or

781
00:39:05,040 --> 00:39:07,120
Speaker 1: it could have been dark energy that was changing. And

782
00:39:07,120 --> 00:39:09,120
Speaker 1: in fact, it's not quite accurate to say that the

783
00:39:09,120 --> 00:39:12,399
Speaker 1: picture of dark energy it's constant, describes the universe very well,

784
00:39:12,440 --> 00:39:15,600
Speaker 1: because there's some controversy there. We measure the dark energy

785
00:39:15,640 --> 00:39:18,680
Speaker 1: in the universe in late times using supernovas and also

786
00:39:18,760 --> 00:39:21,840
Speaker 1: in early times using its effect on the cosmic microwave

787
00:39:21,840 --> 00:39:25,359
Speaker 1: background radiation, we actually get different numbers by a little bit,

788
00:39:25,760 --> 00:39:28,160
Speaker 1: and that's been a persistent tension. It's called the Hubble

789
00:39:28,200 --> 00:39:31,840
Speaker 1: Tension whole podcast episode about that. That inspires people to

790
00:39:31,840 --> 00:39:34,440
Speaker 1: come up with other ideas, something called early dark energy,

791
00:39:34,480 --> 00:39:36,960
Speaker 1: to like add a little bit more dark energy early

792
00:39:37,000 --> 00:39:39,560
Speaker 1: on in the universe. So the very very beginning of

793
00:39:39,560 --> 00:39:42,759
Speaker 1: the universe, big question marks about how much expansion there

794
00:39:42,840 --> 00:39:45,080
Speaker 1: was and what caused it. After that, it's more steady

795
00:39:45,200 --> 00:39:48,920
Speaker 1: and it's well described by universe with almost constant dark energy.

796
00:39:49,560 --> 00:39:51,120
Speaker 1: But I say it's it's sort of a theory, right,

797
00:39:51,200 --> 00:39:55,720
Speaker 1: there's still the possibility that maybe dark energy will increase again,

798
00:39:56,560 --> 00:39:59,919
Speaker 1: or maybe this mysterious you know Inflanton or other quant

799
00:40:00,040 --> 00:40:03,360
Speaker 1: and field with potential energy might kick back in exactly

800
00:40:03,360 --> 00:40:06,200
Speaker 1: because we don't have a good theoretical description, so we

801
00:40:06,239 --> 00:40:09,920
Speaker 1: can't really make predictions. We're just observing things. It's like

802
00:40:09,960 --> 00:40:12,560
Speaker 1: if you're watching the weather and you're noticing some trends, like, hey,

803
00:40:12,600 --> 00:40:14,760
Speaker 1: in southern California, it seems to be the same temperature

804
00:40:14,800 --> 00:40:17,480
Speaker 1: every single day, because I mean, I could predict confidently

805
00:40:17,480 --> 00:40:19,759
Speaker 1: it's always going to be the same temperature only if

806
00:40:19,760 --> 00:40:22,520
Speaker 1: I actually understood what caused them, Like why is it

807
00:40:22,600 --> 00:40:24,600
Speaker 1: the same temperature every day? If I had some understanding

808
00:40:24,600 --> 00:40:28,200
Speaker 1: of the underlying mechanism that I could make some prediction. Otherwise,

809
00:40:28,239 --> 00:40:31,799
Speaker 1: I'm just observing and extrapolating ignorantly. And that's basically what

810
00:40:31,840 --> 00:40:34,840
Speaker 1: we're doing now. We don't understand the mechanism underlying it

811
00:40:34,920 --> 00:40:37,239
Speaker 1: at all. We just see these trends and we make

812
00:40:37,280 --> 00:40:39,759
Speaker 1: simplifying assumptions. I feel like you just described my job

813
00:40:39,800 --> 00:40:45,520
Speaker 1: on this podcast anyway, to extrapolate ignorantly for money, and

814
00:40:45,600 --> 00:40:47,920
Speaker 1: listeners shouldn't take this as a criticism, right, This is

815
00:40:47,920 --> 00:40:50,440
Speaker 1: the first step. This is very, very fresh science. We

816
00:40:50,480 --> 00:40:52,879
Speaker 1: only discovered this was happening a couple of decades ago.

817
00:40:52,960 --> 00:40:56,120
Speaker 1: And the first thing you do is observe and characterize

818
00:40:56,120 --> 00:40:58,800
Speaker 1: and look for patterns, and then you try to build

819
00:40:58,840 --> 00:41:01,160
Speaker 1: up some theory that describe And people are hard at

820
00:41:01,160 --> 00:41:04,359
Speaker 1: work and exactly that, trying to understand what's causing this

821
00:41:04,640 --> 00:41:06,600
Speaker 1: and what its future might be, because, as you say,

822
00:41:06,760 --> 00:41:08,839
Speaker 1: we don't know what's causing it. We don't know if

823
00:41:08,840 --> 00:41:10,960
Speaker 1: it's going to change in the future. Right, And so

824
00:41:11,000 --> 00:41:12,880
Speaker 1: I think we've talked about in the podcast before how

825
00:41:12,920 --> 00:41:16,120
Speaker 1: there are three possibilities. So the dark energy, or at

826
00:41:16,200 --> 00:41:19,719
Speaker 1: least whatever is powering or whatever power is, the expansion

827
00:41:19,719 --> 00:41:21,759
Speaker 1: of the universe could do one of their things. It

828
00:41:21,840 --> 00:41:24,640
Speaker 1: can go away, you can stay the same, or it

829
00:41:24,640 --> 00:41:27,920
Speaker 1: can get even stronger. Right, And so if it goes away,

830
00:41:27,960 --> 00:41:30,879
Speaker 1: then what happens to the universe? It crunches down. If

831
00:41:30,880 --> 00:41:33,160
Speaker 1: it goes away, then the universe is now matter and

832
00:41:33,280 --> 00:41:36,720
Speaker 1: radiation dominated, and those things tend to pull things back together.

833
00:41:36,920 --> 00:41:38,719
Speaker 1: And so then it's back to the question of like,

834
00:41:38,920 --> 00:41:41,560
Speaker 1: is there enough matter to slow things down and pull

835
00:41:41,640 --> 00:41:43,640
Speaker 1: them back together into a big crunch, or is there

836
00:41:43,760 --> 00:41:47,560
Speaker 1: enough velocity already in that expansion so that things skeet

837
00:41:47,600 --> 00:41:50,520
Speaker 1: away from each other, slowing down but never actually coming

838
00:41:50,520 --> 00:41:53,040
Speaker 1: back together. If you just like turned off the dark energy,

839
00:41:53,239 --> 00:41:55,799
Speaker 1: we don't know we can make that calculation. I can't

840
00:41:55,840 --> 00:41:58,760
Speaker 1: make that calculation today on the podcast, but maybe somebody

841
00:41:58,800 --> 00:42:01,359
Speaker 1: out there knows. But nobody's ever done it. It's sort

842
00:42:01,360 --> 00:42:03,920
Speaker 1: of a particular scenario where you had dark energy in

843
00:42:03,960 --> 00:42:06,480
Speaker 1: the universe or fourteen billion years and then suddenly turn

844
00:42:06,520 --> 00:42:09,400
Speaker 1: it off. I don't know if anybody's actually done that calculation.

845
00:42:09,440 --> 00:42:12,400
Speaker 1: All right, Well, that yours may may not crushed together.

846
00:42:12,680 --> 00:42:15,000
Speaker 1: What happens if dark energy stays the same, It's if

847
00:42:15,040 --> 00:42:17,200
Speaker 1: it stays constant that the way it is now. Then

848
00:42:17,239 --> 00:42:20,640
Speaker 1: the expansion of the universe continues, and it continues to accelerate,

849
00:42:20,920 --> 00:42:24,120
Speaker 1: which means that space between things grows faster and faster,

850
00:42:24,640 --> 00:42:28,200
Speaker 1: and over very large distances. That expansion is faster than

851
00:42:28,239 --> 00:42:31,359
Speaker 1: the speed of light, which means that things are disappearing

852
00:42:31,560 --> 00:42:34,719
Speaker 1: past the edge of our cosmic horizon. There are galaxies

853
00:42:34,760 --> 00:42:37,319
Speaker 1: out there who are shooting photons at us, and those

854
00:42:37,320 --> 00:42:40,799
Speaker 1: photons will never arrive because the space between us and

855
00:42:40,840 --> 00:42:44,440
Speaker 1: that galaxy is increasing faster than light is making progress

856
00:42:44,480 --> 00:42:47,560
Speaker 1: through that space. So, in that scenario where dark energy

857
00:42:47,640 --> 00:42:52,080
Speaker 1: stays constant, the observable fraction of the universe gets smaller

858
00:42:52,120 --> 00:42:54,840
Speaker 1: and smaller as time goes on, things start to disappear.

859
00:42:54,920 --> 00:42:56,560
Speaker 1: We don't think in that scenaria of the galaxy will

860
00:42:56,560 --> 00:42:58,719
Speaker 1: there at the party will always have enough gravity to

861
00:42:58,760 --> 00:43:01,439
Speaker 1: hold itself together, and the Earth will still orbit around

862
00:43:01,440 --> 00:43:04,040
Speaker 1: the Sun, but our galaxy will become more and more

863
00:43:04,160 --> 00:43:07,760
Speaker 1: isolated relative to other galaxies. Right. We talked about how

864
00:43:07,800 --> 00:43:10,400
Speaker 1: in this scenario, the nights guy gets dark and darker, right,

865
00:43:10,400 --> 00:43:13,040
Speaker 1: because all the stars, or at least all the galaxies

866
00:43:13,080 --> 00:43:15,759
Speaker 1: out there, will move out of our view, but will

867
00:43:15,800 --> 00:43:18,120
Speaker 1: add the stars move out of out our view the

868
00:43:18,160 --> 00:43:21,040
Speaker 1: ones in our galaxy. Isn't the opposite going to happen? Now?

869
00:43:21,120 --> 00:43:23,759
Speaker 1: The galaxy is probably strong enough, has enough gravity to

870
00:43:23,840 --> 00:43:27,160
Speaker 1: hold itself together if dark energy stays constant, so the

871
00:43:27,200 --> 00:43:31,400
Speaker 1: other galaxies will disappear, and future astronomers will look up

872
00:43:31,400 --> 00:43:33,960
Speaker 1: at the night sky and only see stars in our galaxy,

873
00:43:33,960 --> 00:43:37,160
Speaker 1: and they will think our galaxy is the whole universe

874
00:43:37,560 --> 00:43:40,640
Speaker 1: because they won't be able to see anything else. WHOA,

875
00:43:41,280 --> 00:43:44,719
Speaker 1: but how about future future future astronomers. Isn't there enough

876
00:43:44,760 --> 00:43:47,440
Speaker 1: stuff in our galaxy that it will eventually crunch down

877
00:43:47,480 --> 00:43:50,000
Speaker 1: into a black hole eventually? Yes, it will crunch down

878
00:43:50,000 --> 00:43:53,080
Speaker 1: into a black hole. Gravity will eventually win. Things are

879
00:43:53,120 --> 00:43:56,319
Speaker 1: swirling around and avoiding the inevitable. But you know, things

880
00:43:56,360 --> 00:43:59,040
Speaker 1: bump into each other and lose angular momentum, and they

881
00:43:59,160 --> 00:44:02,200
Speaker 1: radiate energy through gravitational waves. So the very very far

882
00:44:02,320 --> 00:44:06,239
Speaker 1: future is that the supermassive black hole eats our galaxy.

883
00:44:06,360 --> 00:44:08,680
Speaker 1: So the very deep future of the universe, if dark

884
00:44:08,760 --> 00:44:12,120
Speaker 1: energy is constant, is a bunch of black holes isolated

885
00:44:12,160 --> 00:44:14,799
Speaker 1: from each other. Yeah, too far away to even see

886
00:44:14,800 --> 00:44:17,759
Speaker 1: each other, right or affect each other, Yeah, exactly, Each

887
00:44:17,800 --> 00:44:21,160
Speaker 1: one will be past the other's cosmic horizons. Wow, not

888
00:44:21,239 --> 00:44:23,600
Speaker 1: a bright future for the universe. You don't want to

889
00:44:23,600 --> 00:44:27,080
Speaker 1: buy shares in that universe. Unless shares are for flashlights,

890
00:44:27,239 --> 00:44:30,480
Speaker 1: then yeah, those are going to become very, very valuable

891
00:44:30,520 --> 00:44:32,879
Speaker 1: in the future. So then there's a last scenario, which

892
00:44:32,920 --> 00:44:36,000
Speaker 1: is that maybe dark energy will somehow kick back in

893
00:44:36,120 --> 00:44:38,880
Speaker 1: or whatever made the initial inflation of the universe happen,

894
00:44:39,080 --> 00:44:41,560
Speaker 1: that might come back and which will make the universe

895
00:44:41,600 --> 00:44:44,360
Speaker 1: expand even faster than it is now. Yeah, there's this

896
00:44:44,440 --> 00:44:47,439
Speaker 1: fun idea that dark energy will convert into something called

897
00:44:47,680 --> 00:44:50,759
Speaker 1: phantom energy. This is energy which will grow even more

898
00:44:50,880 --> 00:44:54,120
Speaker 1: rapidly than just the expansion of space, so that as

899
00:44:54,200 --> 00:44:57,480
Speaker 1: space expands, the fraction of energy in each chunk of

900
00:44:57,520 --> 00:45:01,360
Speaker 1: space also goes up, which means that the acceleration increases

901
00:45:01,440 --> 00:45:04,279
Speaker 1: faster and faster. Wait, the idea is that dark energy

902
00:45:04,360 --> 00:45:08,759
Speaker 1: somehow evolved like a pokemon like it levels up. You

903
00:45:08,840 --> 00:45:10,719
Speaker 1: just need to buy more and more packs. That's all

904
00:45:10,719 --> 00:45:13,560
Speaker 1: that has to happen for this scenario to unfold. Nobody

905
00:45:13,600 --> 00:45:16,680
Speaker 1: is that the idea that it's like the same energy,

906
00:45:16,719 --> 00:45:18,840
Speaker 1: but somehow it gets kicked up the level or something.

907
00:45:19,360 --> 00:45:23,880
Speaker 1: The theoretical underpinnings of phantom energy are pretty fuzzy. They

908
00:45:23,920 --> 00:45:26,440
Speaker 1: require a bunch of really weird fields that have strange

909
00:45:26,480 --> 00:45:30,120
Speaker 1: things like negative kinetic energy. It's possible for them to

910
00:45:30,200 --> 00:45:32,760
Speaker 1: exist in the universe and sort of wake up only

911
00:45:32,800 --> 00:45:35,840
Speaker 1: in late times. This is the theories that people have developed,

912
00:45:35,840 --> 00:45:39,360
Speaker 1: and they would accelerate the expansion of the universe in

913
00:45:39,560 --> 00:45:42,600
Speaker 1: even more surprising ways because they have very strange kinetic

914
00:45:42,640 --> 00:45:45,319
Speaker 1: and potential energy. But the end result, I guess is

915
00:45:45,320 --> 00:45:48,960
Speaker 1: that it levels up to something called phantom energy, because

916
00:45:49,160 --> 00:45:52,160
Speaker 1: that just sounds more mysterious. I guess it's actually named

917
00:45:52,200 --> 00:45:55,800
Speaker 1: after the movie The Phantom Menace. Guy wrote this paper

918
00:45:55,840 --> 00:45:59,000
Speaker 1: called The Phantom Menace the Future of the Universe, So

919
00:45:59,080 --> 00:46:01,600
Speaker 1: he was a fan. He was defan, he writes in

920
00:46:01,600 --> 00:46:03,800
Speaker 1: the paper quote, a phantom is something which is apparent

921
00:46:03,840 --> 00:46:07,359
Speaker 1: to the site or other senses, but has no corporeal existence,

922
00:46:07,560 --> 00:46:11,120
Speaker 1: an appropriate description for a form of energy necessarily described

923
00:46:11,160 --> 00:46:14,680
Speaker 1: by unorthodox physics. So he's sort of putting in the

924
00:46:14,800 --> 00:46:18,960
Speaker 1: like ghostly category. But did he reference the movie? Oh absolutely,

925
00:46:18,960 --> 00:46:21,160
Speaker 1: it was very much a reference to the movie The

926
00:46:21,239 --> 00:46:24,040
Speaker 1: Phantom Menace that was mentioned in the academic paper The

927
00:46:24,080 --> 00:46:26,799
Speaker 1: Phantom Menace is part of the title of the paper. Yes,

928
00:46:26,800 --> 00:46:30,640
Speaker 1: the Phantom energy totally named after the movie The Phantom Menace,

929
00:46:30,800 --> 00:46:33,120
Speaker 1: or maybe he just named the title after the movie.

930
00:46:33,440 --> 00:46:35,960
Speaker 1: Doesn't mean that Phantom energy was based on the movie,

931
00:46:36,160 --> 00:46:38,600
Speaker 1: does it, Well, the science of Phantom energy is not

932
00:46:38,640 --> 00:46:40,960
Speaker 1: based on the movie. But yeah, he named it phantom

933
00:46:41,040 --> 00:46:42,840
Speaker 1: energy because he was inspired by the use of the

934
00:46:42,880 --> 00:46:45,600
Speaker 1: word phantom from The Phantom Menace. I guess you could

935
00:46:45,640 --> 00:46:49,360
Speaker 1: say he was a fan. I don't know if his

936
00:46:49,440 --> 00:46:51,640
Speaker 1: name was Tom, he should have changed it, But I

937
00:46:51,640 --> 00:46:53,920
Speaker 1: guess the point is that maybe this energy is going

938
00:46:54,000 --> 00:46:56,279
Speaker 1: to increase, level up, get stronger, which is going to

939
00:46:56,320 --> 00:46:59,319
Speaker 1: make the universe expand faster and faster and faster and

940
00:46:59,360 --> 00:47:03,360
Speaker 1: faster and faster, which might rip the universe apart. Right exactly,

941
00:47:03,440 --> 00:47:06,920
Speaker 1: Dark energy by itself will already rip galaxies apart, but

942
00:47:07,160 --> 00:47:10,239
Speaker 1: phantom energy will get more powerful, and so eventually it

943
00:47:10,280 --> 00:47:14,360
Speaker 1: will overcome even the gravity of our galaxy, holding the

944
00:47:14,400 --> 00:47:18,160
Speaker 1: galaxy itself apart, and as time goes on, it will

945
00:47:18,200 --> 00:47:21,799
Speaker 1: increase in power, eventually pulling our Solar system apart, and

946
00:47:21,840 --> 00:47:24,960
Speaker 1: then shredding the Earth and in the deep deep future

947
00:47:25,160 --> 00:47:29,280
Speaker 1: even pulling all atomic bonds apart. WHOA, So you're saying,

948
00:47:29,280 --> 00:47:33,920
Speaker 1: like like space itself will become like inhospitable almost in

949
00:47:33,920 --> 00:47:36,600
Speaker 1: a way. Space will be expanding so much, even at

950
00:47:36,600 --> 00:47:39,919
Speaker 1: the molecular sub atomic level, then not even quarks will

951
00:47:39,960 --> 00:47:42,720
Speaker 1: be able to hang onto each other. Not even quarks

952
00:47:42,760 --> 00:47:45,240
Speaker 1: will be able to pull each other apart. All bonds

953
00:47:45,360 --> 00:47:49,000
Speaker 1: eventually will be weaker than the phantom energy, which will

954
00:47:49,040 --> 00:47:53,440
Speaker 1: overcome everything. It's this which will overcome everything. So like

955
00:47:53,480 --> 00:47:55,279
Speaker 1: two quarks will be hanging out to each other, but

956
00:47:55,320 --> 00:47:57,640
Speaker 1: then space will rip it apart, and then they'll never

957
00:47:57,640 --> 00:48:00,480
Speaker 1: see each other again ever, right, Yeah, the final end

958
00:48:00,520 --> 00:48:02,160
Speaker 1: of the universe is sort of similar to what we

959
00:48:02,239 --> 00:48:06,000
Speaker 1: described with dark energy, where you had black holes separated

960
00:48:06,000 --> 00:48:09,359
Speaker 1: by essentially infinitely expanding space, so they can't communicate as

961
00:48:09,360 --> 00:48:12,759
Speaker 1: no interaction except the phantom energy. Version of that is

962
00:48:12,800 --> 00:48:16,759
Speaker 1: that particles are now separated by infinitely expanding space, so

963
00:48:16,800 --> 00:48:19,080
Speaker 1: they can't interact with each other. They can't even tell

964
00:48:19,440 --> 00:48:22,960
Speaker 1: that there are other particles in the universe. WHOA. So

965
00:48:23,000 --> 00:48:26,640
Speaker 1: then like every single particle in the known existence in

966
00:48:26,719 --> 00:48:29,480
Speaker 1: the universe will be by itself with no way to

967
00:48:29,520 --> 00:48:33,160
Speaker 1: communicate with any other particle unless I guess the space

968
00:48:33,239 --> 00:48:35,920
Speaker 1: makes a new particle next to it or something. Right, Well,

969
00:48:35,920 --> 00:48:38,160
Speaker 1: that's the really complicated thing about corks, right, is that

970
00:48:38,239 --> 00:48:40,759
Speaker 1: corks do not like to be by themselves. We think

971
00:48:40,760 --> 00:48:43,920
Speaker 1: that as you pull quarks apart, there's so much energy

972
00:48:43,960 --> 00:48:46,279
Speaker 1: in the strong force that it pops new corks out

973
00:48:46,320 --> 00:48:48,880
Speaker 1: of the vacuum. So nobody actually knows what's going to

974
00:48:48,960 --> 00:48:51,399
Speaker 1: happen to quirks. It might be that as phantom energy

975
00:48:51,440 --> 00:48:55,600
Speaker 1: pulls them apart, it creates this exponential cascade of particles

976
00:48:55,640 --> 00:48:59,359
Speaker 1: being produced, filling space with all sorts of quirks. So

977
00:48:59,400 --> 00:49:00,960
Speaker 1: we don't know who who's gonna win in the end.

978
00:49:00,960 --> 00:49:03,640
Speaker 1: They're the strong force or phantom energy. You mean, like

979
00:49:03,680 --> 00:49:07,440
Speaker 1: as the universe rips apart, it's also gonna make new quarks.

980
00:49:08,480 --> 00:49:10,520
Speaker 1: So what you're saying, like opening a bag of popcorns,

981
00:49:10,760 --> 00:49:12,960
Speaker 1: you rip it open, all these corks pop out. That's

982
00:49:12,960 --> 00:49:14,800
Speaker 1: what happens when we make pairs of quarks with the

983
00:49:14,880 --> 00:49:18,000
Speaker 1: large Hadron collider that have a large velocity relative to

984
00:49:18,000 --> 00:49:20,600
Speaker 1: each other. They created back to back. They're zooming away

985
00:49:20,600 --> 00:49:22,520
Speaker 1: from each other near the speed of light, and they

986
00:49:22,560 --> 00:49:25,839
Speaker 1: create this enormous shower of new corks. Between them out

987
00:49:25,880 --> 00:49:29,359
Speaker 1: of the energy contained in the strong force bonds between them.

988
00:49:29,440 --> 00:49:31,480
Speaker 1: And so we think the same thing might happen to

989
00:49:31,760 --> 00:49:35,080
Speaker 1: all quarks in the universe when phantom energy tries to

990
00:49:35,080 --> 00:49:37,840
Speaker 1: pull them apart from their partners. M hmm, but I

991
00:49:37,880 --> 00:49:40,120
Speaker 1: guess it will be sort of. I mean, things will

992
00:49:40,120 --> 00:49:42,960
Speaker 1: happen in order, like we won't be around to see that, right, Like,

993
00:49:43,760 --> 00:49:46,680
Speaker 1: first the galaxy is gonna, you know, rip the stars

994
00:49:46,719 --> 00:49:49,600
Speaker 1: within the gas. They're going to rip apart, but maybe

995
00:49:49,640 --> 00:49:51,759
Speaker 1: it's not strong enough to rip apart solar systems, but

996
00:49:51,800 --> 00:49:54,080
Speaker 1: eventually it's going to rip apart solar systems. And then

997
00:49:54,120 --> 00:49:57,640
Speaker 1: eventually it's going to rip apart stars and planets. So

998
00:49:57,680 --> 00:50:00,400
Speaker 1: the final big rip, according to some calculation, is going

999
00:50:00,440 --> 00:50:03,640
Speaker 1: to be in about twenty billion years. Wait what we

1000
00:50:03,680 --> 00:50:06,760
Speaker 1: have a time estimate here? We have a time based

1001
00:50:06,760 --> 00:50:09,480
Speaker 1: on estimates of the amount of phantom energy that might

1002
00:50:09,520 --> 00:50:12,400
Speaker 1: be in the universe. This is total speculation, just like

1003
00:50:12,680 --> 00:50:14,920
Speaker 1: pick some numbers and see how it plays out. But

1004
00:50:14,960 --> 00:50:17,280
Speaker 1: it's fun to think about, like if dark energy starts

1005
00:50:17,280 --> 00:50:20,200
Speaker 1: to accelerate, now, is that what you mean at a

1006
00:50:20,440 --> 00:50:23,320
Speaker 1: certain value, like a random value, or what would value

1007
00:50:23,360 --> 00:50:25,920
Speaker 1: like at a random value. Yeah, there's a whole spectrum

1008
00:50:25,920 --> 00:50:28,520
Speaker 1: of possible different levels of phantom energy that might exist

1009
00:50:28,520 --> 00:50:30,319
Speaker 1: in the universe, and they just would like pick a

1010
00:50:30,400 --> 00:50:32,279
Speaker 1: number and they put it in and they can make

1011
00:50:32,360 --> 00:50:35,440
Speaker 1: specific predictions. Though these are not like weather reports. You

1012
00:50:35,440 --> 00:50:38,359
Speaker 1: shouldn't base your life around these. It's just like illustrative,

1013
00:50:38,440 --> 00:50:40,640
Speaker 1: like to think about how fast things would happen. But

1014
00:50:40,680 --> 00:50:43,560
Speaker 1: with enough phantom energy happening tomorrow, the universe could be

1015
00:50:43,719 --> 00:50:46,560
Speaker 1: rip apart the day after tomorrow. Right, So the twenty

1016
00:50:46,600 --> 00:50:49,600
Speaker 1: two billion years is just based on a number. It's

1017
00:50:49,640 --> 00:50:51,960
Speaker 1: just based on a number, but it's a plausible number

1018
00:50:52,040 --> 00:50:55,120
Speaker 1: when it's not completely inconsistent with what we see today

1019
00:50:55,160 --> 00:50:57,960
Speaker 1: in the universe. Oh, meaning like if our measurements are

1020
00:50:57,960 --> 00:51:00,520
Speaker 1: a little bit off and that we're rang in the sands,

1021
00:51:00,520 --> 00:51:03,920
Speaker 1: then maybe the universe is expanding faster and faster and

1022
00:51:04,000 --> 00:51:06,359
Speaker 1: dark energy is not constant. Than this is how much

1023
00:51:06,400 --> 00:51:09,040
Speaker 1: time we have, Like this is the worst case scenario

1024
00:51:09,200 --> 00:51:12,000
Speaker 1: based on our the fuzziness of our measurement. Yeah, and

1025
00:51:12,040 --> 00:51:14,840
Speaker 1: the good news is that we have twenty billion years

1026
00:51:14,880 --> 00:51:17,920
Speaker 1: until the final big rip. And the double good news

1027
00:51:18,080 --> 00:51:20,520
Speaker 1: is that we think that the Earth will survive until

1028
00:51:20,600 --> 00:51:25,359
Speaker 1: about thirty minutes before the end. Oh, that's good, So

1029
00:51:25,440 --> 00:51:28,040
Speaker 1: we'll be around except for the last thirty minutes of it.

1030
00:51:28,280 --> 00:51:30,360
Speaker 1: And between thirty minutes and the end is when the

1031
00:51:30,440 --> 00:51:33,160
Speaker 1: Earth will get ripped apart and then eventually atoms, so

1032
00:51:33,200 --> 00:51:35,919
Speaker 1: we'll miss the last fireworks, but we'll still be here

1033
00:51:35,960 --> 00:51:39,359
Speaker 1: for most of it. Well, assuming the Earth is still here, right,

1034
00:51:39,520 --> 00:51:41,400
Speaker 1: this is the Earth supposed to be swallowed up by

1035
00:51:41,440 --> 00:51:43,919
Speaker 1: the Sun in like eight billion years. Yeah, the Sun

1036
00:51:44,000 --> 00:51:46,560
Speaker 1: only has a few more billion years. But assuming that

1037
00:51:46,600 --> 00:51:48,520
Speaker 1: we know, we move the Earth to some other Sun,

1038
00:51:48,680 --> 00:51:51,160
Speaker 1: or we rehab the Sun or something like that, or

1039
00:51:51,200 --> 00:51:53,600
Speaker 1: we maybe change the Earth's orbit and we end up

1040
00:51:53,680 --> 00:51:56,439
Speaker 1: orbiting a white dwarf for billions of years. That could

1041
00:51:56,440 --> 00:51:58,400
Speaker 1: happen if we managed to do that sort of solar

1042
00:51:58,400 --> 00:52:01,600
Speaker 1: system engineering. Then the timeline is we have twenty billion

1043
00:52:01,680 --> 00:52:05,480
Speaker 1: years until phantom energy pulls the universe apart. If phantom

1044
00:52:05,560 --> 00:52:07,680
Speaker 1: energy even is a real thing, right, it might even

1045
00:52:07,680 --> 00:52:11,160
Speaker 1: be like the descendants of Luke Skywalker who are watching

1046
00:52:11,200 --> 00:52:13,279
Speaker 1: this happen may or may not be human. As we

1047
00:52:13,360 --> 00:52:16,960
Speaker 1: discussed Earth, they certainly look human, well so do I, Daniel.

1048
00:52:18,400 --> 00:52:20,120
Speaker 1: I do have my doubts about that, and you know,

1049
00:52:20,160 --> 00:52:23,960
Speaker 1: the current evidence suggests that dark energy seems mostly constant.

1050
00:52:24,200 --> 00:52:26,040
Speaker 1: We don't see it ticking up. That we do have

1051
00:52:26,080 --> 00:52:28,520
Speaker 1: some questions about what's going on in the early universe.

1052
00:52:28,840 --> 00:52:31,680
Speaker 1: There are a few measurements that disagree with that, like

1053
00:52:32,080 --> 00:52:36,320
Speaker 1: studies of distant quasars that might suggest some slight increase

1054
00:52:36,400 --> 00:52:40,360
Speaker 1: in the energy density of dark energy in recent times.

1055
00:52:40,400 --> 00:52:43,080
Speaker 1: But for the most part, mainstream cosmologists think that dark

1056
00:52:43,160 --> 00:52:46,560
Speaker 1: energy is constant. That's the simplest explanation. Though again, we

1057
00:52:46,600 --> 00:52:49,200
Speaker 1: don't understand the mechanism for it, so we can't confidently

1058
00:52:49,239 --> 00:52:52,000
Speaker 1: make hard predictions. Right, we don't know what it is.

1059
00:52:52,040 --> 00:52:53,719
Speaker 1: And in fact, I feel like we're sort of defining

1060
00:52:53,719 --> 00:52:55,680
Speaker 1: it to be constant, and so we're measuring it to

1061
00:52:55,680 --> 00:52:58,760
Speaker 1: be constant. But actually the history says that it maybe

1062
00:52:58,880 --> 00:53:02,160
Speaker 1: wasn't constant. That's actually true, and as we make observations,

1063
00:53:02,200 --> 00:53:05,319
Speaker 1: we add bells and whistles to our models to accommodate

1064
00:53:05,320 --> 00:53:07,600
Speaker 1: what we see, and then we try to explain it

1065
00:53:07,640 --> 00:53:10,480
Speaker 1: and describe it. Wow to me. In the far future, though,

1066
00:53:10,560 --> 00:53:12,839
Speaker 1: somebody will make a movie that says, a long time ago,

1067
00:53:13,719 --> 00:53:17,160
Speaker 1: n galaxy, far far away, you figured out the phantom

1068
00:53:17,239 --> 00:53:21,080
Speaker 1: energy and two guys talked about it on a podcast.

1069
00:53:21,320 --> 00:53:24,600
Speaker 1: Not a very exciting movie. But you know that's as

1070
00:53:24,640 --> 00:53:27,440
Speaker 1: you say, as you seem to think that's the trend

1071
00:53:27,480 --> 00:53:31,640
Speaker 1: for these Disney Plus shows. No comment, We're just doing

1072
00:53:31,680 --> 00:53:36,799
Speaker 1: it in with less special effects. All right, Well, I

1073
00:53:36,800 --> 00:53:40,040
Speaker 1: guess stay tuned for two two billion years and then

1074
00:53:40,040 --> 00:53:42,640
Speaker 1: we'll find out if that's true or not exactly. And

1075
00:53:42,760 --> 00:53:45,040
Speaker 1: as time goes on, we'll learn more and more about

1076
00:53:45,040 --> 00:53:47,800
Speaker 1: the universe, and we will refine our models and hopefully

1077
00:53:48,040 --> 00:53:51,360
Speaker 1: be able to anticipate it long before it happens, or

1078
00:53:51,560 --> 00:53:54,000
Speaker 1: just hang on as long as we can. All right, Well,

1079
00:53:54,040 --> 00:53:56,759
Speaker 1: we hope you enjoyed that. Thanks for joining us, See

1080
00:53:56,760 --> 00:54:06,680
Speaker 1: you next time. Yea. Thanks for listening, and remember that

1081
00:54:06,800 --> 00:54:09,560
Speaker 1: Daniel and Jorge Explain the Universe is a production of

1082
00:54:09,640 --> 00:54:13,000
Speaker 1: I Heart Radio. For more podcast from my Heart Radio,

1083
00:54:13,160 --> 00:54:16,720
Speaker 1: visit the i heart Radio app, Apple Podcasts, or wherever

1084
00:54:16,840 --> 00:54:18,520
Speaker 1: you listen to your favorite shows.