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Speaker 1: When you pop a piece of cheese into your mouth,

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Speaker 1: you're probably not thinking about the environmental impact, but the

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Speaker 3: Hey, Daniel, do you think physics is in a rut?

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Speaker 1: A rut like we've been solving deep problems and delivering

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Speaker 1: amazing technology for too long.

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Speaker 3: You're getting tired of it? Yeah, I mean it's getting

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Speaker 3: a little repetitive all these discoveries. No you No, I mean, like,

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Speaker 3: is it on the right track? You know? Do you

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Speaker 3: think it will it get to the final deep questions

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Speaker 3: about the universe?

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Speaker 1: I don't know. Sometimes I wonder if we need like

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Speaker 1: a revolution in physics.

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Speaker 3: Ooh, does physics need to be disrupted?

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Speaker 1: Somebody out there should start uber for physics.

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Speaker 3: I'm more of a lift person, to be honest, I

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Speaker 3: think they have a better outlook in the world. But yes,

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Speaker 3: that's what I mean. You know, I want to be

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Speaker 3: able to call a physicist anytime with my phone.

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Speaker 1: Well, you already have that. That's this podcast.

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Speaker 3: Nice, I'll give you four stars. Daniel here. Hi, I

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Speaker 3: am Jorge. I'm a cartoonist and the creator of PhD comics. Hi.

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Speaker 1: I'm Daniel Whitson. I'm a particle physicist and I'm here

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Speaker 1: to answer any question of physics on your app anytime.

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Speaker 3: Welcome to our podcast. Daniel and Jorge invent new physics

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Speaker 3: apps for people who need physics on demand.

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Speaker 1: Daniel and Jorge makeup arrable business ideas and pretend they're awesome.

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Speaker 3: No, it's Daniel and Jorge Explain the Universe, a production

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Speaker 3: of iHeart Radio.

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Speaker 1: In which we talk about all the things amazing and

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Speaker 1: beautiful but crazy and bonkers about our universe because the

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Speaker 1: more we learn, the more it makes sense, the more

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Speaker 1: it seems surprising and amazing.

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Speaker 3: You know, did we joke about it? But I think

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Speaker 3: it would be kind of a useful app. Don't you think,

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Speaker 3: like anytime anyone has a question about anything, you could

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Speaker 3: just request a physicist on your phone and the nearest

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Speaker 3: or the most available physicists would answer and then answer

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Speaker 3: your question.

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Speaker 1: Do you think that would be used a lot? Like?

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Speaker 1: What kind of questions would people ask?

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Speaker 3: How do we reconcile the different theories about quantum physics.

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Speaker 3: I'm sure we must know.

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Speaker 1: I think it's more prosaic. It's like, can I build

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Speaker 1: a force field to keep my teenager in his bedroom

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Speaker 1: all night long?

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Speaker 3: Also, how does my toaster work?

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Speaker 1: Why doesn't my toaster work? That'd probably be the number

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Speaker 1: one question. Can you come fix my toaster? No, we're

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Speaker 1: not engineers. A different uber for that.

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Speaker 3: Yeah, but think about all those grad students and post

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Speaker 3: talks and physics who are looking for a little extra money.

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Speaker 3: You know they would, I'm sure they would sign up

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Speaker 3: to answer people's questions.

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Speaker 1: Yeah, you know, there actually is a physics consulting service

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Speaker 1: where if you think you have the great next theory

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Speaker 1: of physics but you're not being taken seriously by the

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Speaker 1: mainstream establishment, there is a service where expert physicists will

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Speaker 1: read your theory and give you like top level criticism

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Speaker 1: of it. Why it's probably not the winner of the

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Speaker 1: next year's Nobel Prize.

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Speaker 3: Yeah, it's called Daniel at danielanhorge dot com.

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Speaker 1: It's true. There are people who send me their theories

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Speaker 1: to questions at Danielinhorge dot com and I try to

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Speaker 1: take a look at them. But there is a service

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Speaker 1: which will spend you know, half an hour or an

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Speaker 1: hour actually digging into your theory. Yeah.

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Speaker 3: Wow, But they charge a lot, don't they. Don't they

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Speaker 3: charge you like fifty dollars an hour or something.

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Speaker 1: You think that's a lot. You think, like, you know,

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Speaker 1: deep deep expertise of the uni verse should come in

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Speaker 1: like seven to fifty an hour.

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Speaker 3: Sure, I mean, you know, I want to know how

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Speaker 3: my toaster works, but not for fifty dollars. We want

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Speaker 3: to buy any toaster omen for fifty dollars.

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Speaker 1: Well, then I guess you don't really want to know

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Speaker 1: how it works. You just want to buy a new one.

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Speaker 3: I want to buy a transparent toaster so I can

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Speaker 3: see how it works.

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Speaker 1: Well, that's the difference between the scientist and the engineer.

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Speaker 1: The engineer just wants to make it work, and the

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Speaker 1: scientist wants to know why it doesn't work.

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Speaker 3: Yeah, we just want to eat toast. That's the basic difference.

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Speaker 1: But sometimes scientists also want a theory that just works.

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Speaker 1: And in physics, we we're making progress towards sort of

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Speaker 1: like answering those deep questions of the universe, but we're

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Speaker 1: not quite there yet.

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Speaker 3: Yeah, you guys have been pretty successful. You have a

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Speaker 3: standard model of the universe and some pretty good theories.

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Speaker 3: You know, you have the standard model, not the not

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Speaker 3: the non standard model.

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Speaker 1: We should have called it something else, right, standard model

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Speaker 1: is just so boring. It's like the beige model of

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Speaker 1: the universe. We should have called it the amazing model.

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Speaker 3: Yeah, but you have pretty much everything answered right, except

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Speaker 3: for some basic things about the universe.

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Speaker 1: Yeah, we've made a lot of progress, which is incredible.

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Speaker 1: We've explained electromagnetism, we've explained the weak force. We've made

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Speaker 1: a lot of progress and understanding the strong nuclear force.

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Speaker 1: And then in a totally different camp, with totally different people,

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Speaker 1: using completely different mathematics and ways of thinking, we've made

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Speaker 1: some inroads into understanding gravity.

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Speaker 3: Yeah, but there are some You have all these great theories,

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Speaker 3: but there's something not quite right right, Like it works,

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Speaker 3: it's pretty successful for a lot of things, but there's

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Speaker 3: something kind of fundamentally almost wrong with all of your theories.

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Speaker 1: What didn't you say, Yeah, the problem is we have

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Speaker 1: no theory that describes sort of all of it. We

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Speaker 1: have people who started from the quantum mechanical side of

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Speaker 1: things understanding that building an incredible mind bending theory of

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Speaker 1: the universe that seems to be like an accurate description

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Speaker 1: of the way things actually are. And then we have

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Speaker 1: people working from the other side, starting from gravity and

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Speaker 1: saying like, let's understand gravity is a bending of space man,

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Speaker 1: and they're actually making progress. Also, the problem is these

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Speaker 1: two theories don't agree with each other. They don't play well.

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Speaker 1: They have completely different views of how the universe actually is.

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Speaker 3: They're sort of incompatible. It's kind of like if you're

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Speaker 3: building a bridge across the Atlantic and you know, you

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Speaker 3: build one side starts building a bridge, and the other

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Speaker 3: side starts building a bridge from their site, and you

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Speaker 3: find out that you're nowhere near each other in the middle.

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Speaker 1: Yeah, exactly. Or you're using technologies which just cannot fit together.

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Speaker 1: And that's the problem. Right You're hoping that there is

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Speaker 1: one truth that you can start in different places in

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Speaker 1: your investigation and sort of work together to find the

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Speaker 1: central truth. But sometimes we wonder if these models just

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Speaker 1: depend on your perspective. There's different ways to look at

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Speaker 1: the universe, and some are successful and some are limited,

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Speaker 1: and so we don't know, like, which is the right

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Speaker 1: way to look at the universe. If either of them

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Speaker 1: are even right, or if we need something totally.

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Speaker 3: New, right, if either of them right, because it almost

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Speaker 3: sounds like maybe both of them are not looking at

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Speaker 3: the world old at the universe in quite the right way,

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Speaker 3: you know, if you can't make them work together.

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Speaker 1: Yeah, And there's a lot of examples in history where

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Speaker 1: physics has been like, very confidently almost wrapped everything up

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Speaker 1: except for a couple of little details which turn out

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Speaker 1: when you pull on them, unravel everything and reveal like

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Speaker 1: a completely different view of the universe. That was quantum mechanics,

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Speaker 1: you know, in the late eighteen hundreds, people felt like

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Speaker 1: we've almost got this thing wrapped up except for like,

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Speaker 1: you know, the photoelectric effect and the black body radiation,

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Speaker 1: which revealed, of course that the universe is quantized on

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Speaker 1: a fundamental scale, which blew everybody's minds.

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Speaker 3: Kind of makes you wonder if maybe physics needs to

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Speaker 3: be shaken up a little bit, you know, kind of

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Speaker 3: reset or you know, disrupted, or you know, start from

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Speaker 3: a totally new perspective.

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Speaker 1: Yeah, I think it's possible physics today has all those

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Speaker 1: elements of needing a new idea, of needing, a new

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Speaker 1: perspective of discovering of stumbling over something which shows us

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Speaker 1: that we've just been asking the wrong questions or starting

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Speaker 1: our solutions from the wrong point of view. And that's

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Speaker 1: not embarrassing, you know. That's the way we explore the world.

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Speaker 1: We start from our current understanding. We see how long

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Speaker 1: it works, and when it breaks, we think, can we

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Speaker 1: just add another little widget to it, or do we

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Speaker 1: have to toss everything out and build it from a

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Speaker 1: different kind of bit.

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Speaker 3: In today's episode, we'll be talking about one such idea

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Speaker 3: that might help bridge this connector gap between quantum mechanics

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Speaker 3: and gravity. And it's a pretty new theory, wouldn't you say.

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Speaker 3: It's sort of it's come out in the last maybe

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Speaker 3: what ten years, twenty years.

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Speaker 1: I think it has its history in the eighties, but

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Speaker 1: it's been picking up steam in the last ten or

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Speaker 1: fifteen years, and it's sort of emerging as a dark horse.

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Speaker 1: It was like first was sort of laughed off as

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Speaker 1: a fringe theory and you know, not nearly as popular

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Speaker 1: as other theories of everything in quantum gravity, and so

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Speaker 1: I think it's recently gaining some sort of respectability.

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Speaker 3: It's like millennials, you know, born in the eighties but

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Speaker 3: kind of easily discounted. But now they're taking over the world.

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Speaker 1: Are millennials getting respectable? When did that happen?

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Speaker 3: When we die?

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Speaker 1: Then I'm working on my theory of quantum respectability and

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Speaker 1: currently I have zero.

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Speaker 3: There you go. So today we'll be talking about about

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Speaker 3: that theory. And the theory is loop quantum gravity. What

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Speaker 3: is it? Why is it in a loop? And will

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Speaker 3: it solve all the problems in physics?

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Speaker 1: And here I have to make a shout out to

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Speaker 1: one of our listeners, Jim Milcho. Jim has been sending

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Speaker 1: me questions for about as long as we've been doing

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Speaker 1: this podcast, and he has been consistently asking for a

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Speaker 1: podcast episode about loop quantum gravity. So thanks for your patience, Jim,

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Speaker 1: here's your episode.

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Speaker 3: Awesome. As he said you, any idea is worthy of

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Speaker 3: a noble price.

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Speaker 1: Yet Jim has sent a lot of ideas and they're

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Speaker 1: always fun to read. So if you have ideas about

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Speaker 1: the universe, or just questions, or there's something you really

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Speaker 1: want to understand more deeply and you think we might

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Speaker 1: be able to break it down, please send your questions,

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Speaker 1: your suggestions, your fundamental new theories of the universe. Two

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Speaker 1: questions at Daniel and Jorge dot com.

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Speaker 3: Yeah, thanks to Jim for listening and to everyone out

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Speaker 3: there listening. And so as usual, we were wondering how

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Speaker 3: many people out there know or have heard of lup

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Speaker 3: quantum gravity. It's sort of a it's sort of a

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Speaker 3: it has two sort of technical familiar words, but then

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Speaker 3: a pretty common word, which is loop.

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Speaker 1: I was very curious in these interviews to see if

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Speaker 1: anybody had heard this thing and had any ideas. So

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Speaker 1: I went in with a completely open mind. So before

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Speaker 1: you hear these answers, thanks to yourself. Do you know

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Speaker 1: what luke quantum gravity is? Could you describe it well?

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Speaker 3: Would you answer? Here's what people had to say. I mean,

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Speaker 3: I would assume it has something to do with gravity,

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Speaker 3: nothing at all.

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Speaker 1: Nothing at all, nothing at all. So I heard of

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Speaker 1: quantum mechanics. I've read like Brief History of Time. Okay,

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Speaker 1: I don't know what luke quantum gravity could be.

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Speaker 3: What came to mind at first was entanglement. But I

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Speaker 3: don't think that necessarily has anything to do with that.

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Speaker 1: So it's just as opposed to just making up something

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Speaker 1: that I think it might be.

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Speaker 4: I don't know, I.

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Speaker 1: Have not no, no, idea. What I am, No, I haven't,

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Speaker 1: I do nothing.

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Speaker 3: I don't know, all right, not a lot of penetration

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Speaker 3: in the public market.

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Speaker 1: No, these folks have to work on their pr for sure. Ye,

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Speaker 1: string theory has them beat, for sure. Maybe they need

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Speaker 1: to get it mentioned in the next Big Bang Theory episode.

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Speaker 3: Oh maybe we should create a septem called loop quantum gravity.

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Speaker 1: I want to see you pitching that.

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Speaker 3: Like, Hey, it work for the Big Bang Theory. We

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Speaker 3: just need another physics theory named titled sitcom that makes

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Speaker 3: fun of nerds.

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Speaker 1: Yeah, well, I'm in as long as we have characters

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Speaker 1: that both are smart and can talk to human beings.

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Speaker 3: Oh really, Yeah, do you know any oh that hurts? Man?

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Speaker 1: That hurts so not?

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Speaker 3: Well, not a lot of people seem to have heard

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Speaker 3: of it. I mean I imagine they Most of them

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Speaker 3: have heard of quantum mechanics or heard the word quantum

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Speaker 3: if anything, from the Marvel movies, and they surely have

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Speaker 3: heard of gravity. But loop quantum gravity is pretty pretty unknown.

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Speaker 1: Yeah, it's a little bit esoteric, but it's fascinating and

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Speaker 1: it has really interesting ideas, and those ideas could have

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Speaker 1: really deep implications. It's the kind of theory, which, if

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Speaker 1: it's correct, really changes the way we think about the

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Speaker 1: entire universe and the fundamental nature of our relationship with it.

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Speaker 1: So it's super fun to think about, and it's also

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Speaker 1: really complicated and very technical, and there's a humongous amount

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Speaker 1: of complicated math involved, none of which none of which

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Speaker 1: you will have to understand together basic ideas today.

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Speaker 3: Which is why Daniel, you went out there and found

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Speaker 3: an expert to talk to about this topic, right.

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Speaker 1: That's right, because I'm a particle physicist and my expertise

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Speaker 1: doesn't extend to theories of quantum gravity. So I went

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Speaker 1: and I talked to Bianca Ditrich. She's a professor at

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Speaker 1: the Perimeter Institute in Canada, and she's an active researcher

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Speaker 1: on the forefront of quantum gravity.

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Speaker 3: So here is Bianca.

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Speaker 5: So my name is Bianca di originally from Germany. Also

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Speaker 5: studied in Germany and then oscillated between Canada and Europe

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Speaker 5: a number of times and aed upt in Canada. It's

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Speaker 5: a Calameter Institute faculty researcher.

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Speaker 3: All right, cool, So Bianca explain to you what loop

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Speaker 3: quantum gravity is.

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Speaker 2: Yeah.

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Speaker 1: I had a long conversation with Bianca about why we

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Speaker 1: need loop quantum gravity, how it solves the problems in

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Speaker 1: physics where the current criticisms of it are, how we

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Speaker 1: could test it, And of course then I had to

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Speaker 1: ask her at the end about black holes.

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Speaker 3: Of course, because every good conversation ends in a black hole, literally, right,

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Speaker 3: maybe at the end of the universe, all that every

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Speaker 3: conversation everyone will ever have, all that information will end

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Speaker 3: up maybe in a black hole.

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Speaker 1: Well, what happens if you take a black hole and

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Speaker 1: you put it in a toaster oven? Oh, there's a

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Speaker 1: question nobody's ever asked a physics I need to ask that.

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Speaker 3: Get a crunchy outside, but the inside will still be cold.

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Speaker 1: Black hole temperature. Yes, So what if I put a

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Speaker 1: black hole in a microwave? Then do I heat up

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Speaker 1: the inside of the black hole? That's a question I've

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Speaker 1: never thought of. That's really a fun question.

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Speaker 3: All right, Well, step us through what Janka explained to you.

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Speaker 3: Daniel was so first of all, I guess, what is

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Speaker 3: this big problem in physics that that needs to be fixing.

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Speaker 1: The big problem is that, as we said earlier, we

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Speaker 1: have two different basic ideas about sort of how the

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Speaker 1: universe works at the smallest scale, and they start from

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Speaker 1: very different places, and as you said, they when they

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Speaker 1: come together across the Atlantic, they just don't meet. And

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Speaker 1: those two ideas are quantum mechanics and general relativity Einstein's

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Speaker 1: theory of gravity.

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Speaker 3: It's weird to me that there would be two so many,

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Speaker 3: so different theories about the universe. You know, wouldn't they

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Speaker 3: all sort of meet at the the you know, plus

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Speaker 3: and minus mathematical level.

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Speaker 1: Well, you'd hope so. And this is sort of the

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Speaker 1: way physics starts. You know, if you're a caveman cave

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Speaker 1: woman physicist, you begin building your model of the universe

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Speaker 1: by sort of looking at all this stuff around you,

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Speaker 1: cataloging what it can do, and then saying, can I

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Speaker 1: understand all of this stuff in its simplest possible terms.

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Speaker 1: And so you're like, all right, there's the thing where

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Speaker 1: things fall down. There's a thing where lightning comes from

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Speaker 1: the sky. You know, there's a thing where there's wind.

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Speaker 1: And then you have a very long list of stuff

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Speaker 1: and you try to boil it down and say, oh,

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Speaker 1: you know, this lightning thing is the same as this

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Speaker 1: other thing where I get zapped and things falling down

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Speaker 1: is actually the same thing as stars moving through the sky.

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Speaker 1: There's all these moments when we sort of shrunk the

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Speaker 1: list of ideas we need to explain the universe. And

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Speaker 1: so you hope that as this list gets short and shorter,

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Speaker 1: they fit together nicely. And that's happened a lot of

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Speaker 1: time so far. Electricity is the same thing as magnetism,

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Speaker 1: and it's all part of this other thing called the electroweakforce.

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Speaker 1: That has happened. But sometimes you get you know, you

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Speaker 1: get two puzzle pieces and they just don't fit together

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Speaker 1: all right.

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Speaker 3: So maybe step reminders, Daniel, what each of these theories are, Like,

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Speaker 3: what's the easy way to describe what general relativity is?

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Speaker 3: And what's the easy way to describe what quantum mechanics is.

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Speaker 1: So general relativity is a way to try to understand

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Speaker 1: what is gravity. And remember that Newton said gravity is

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Speaker 1: things pulling on each other, Things that have mass pull

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Speaker 1: on each other.

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Speaker 3: So it's like a force. Yeah, Newton, that was the

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Speaker 3: old thinking.

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Speaker 1: That was the old thinking. Newton thought gravity is a force,

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Speaker 1: and it seems kind of like a force. It acts

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Speaker 1: like a force like electricity and magnetism. And he was

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Speaker 1: able to write down an equation that described how the

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Speaker 1: Earth moved around the Sun, and how the Moon moved

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Speaker 1: around the Earth. And it works pretty well. Now. Einstein

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Speaker 1: came along and he gave us general relativity, which is

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Speaker 1: a complete reconception of how gravity works. He said, no, no,

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Speaker 1: gravity is not a force. Gravity is a change in

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Speaker 1: the shape of space and time itself. Like you have

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Speaker 1: a blob of mass or blob of any kind of

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Speaker 1: energy density, it changes the shape of and that's what

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Speaker 1: makes things move in curves rather than moving in what

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Speaker 1: feels like a straight line to us. Things move through

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Speaker 1: bent space.

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Speaker 3: It's not like a mysterious invisible force that pulls things together.

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Speaker 3: It's more like when things exist, they they bend the

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Speaker 3: space around them, and that's why they come together. Yeah.

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Speaker 1: And it's a beautiful idea and it's been tested in

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Speaker 1: exillion ways and it works. It describes very tiny deviations

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Speaker 1: in Mercury's orbit. It describes how light bends around the

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Speaker 1: Moon during an eclipse. Big stuff, big stuff, Yeah, really

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Speaker 1: thoroughly extensively tested. It predicted gravitational waves, which we've actually

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Speaker 1: seen black holes too, right, black holes. Yeah. And the

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Speaker 1: thing to understand the things that's going to be make

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Speaker 1: it in conflict with quantum mechanics is that it's a

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Speaker 1: classical theory, meaning that it assumes that you can describe

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Speaker 1: everything perfectly, that everything has a position and a direction

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Speaker 1: and a location, right, and that the space is operating

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Speaker 1: in is smooth, like you can subdivide space as many

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Speaker 1: times as you want between me and you. There's an

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Speaker 1: infinite possible locations for like a ball that we're throwing

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Speaker 1: back and forth. That's Einstein's vision of space.

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Speaker 3: Right. It assumes that everything is kind of smooth and

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Speaker 3: continuous and there are no bumps in the universe at

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Speaker 3: the microscopic level.

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Speaker 1: That's right. You can zoom in forever according to Einstein

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Speaker 1: and general relativity, and things still stay smooth and everything

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Speaker 1: has a fixed location. Right, The ball is somewhere, and

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Speaker 1: space and time makes some sense.

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Speaker 3: There's no uncertainty or weird or weirdness.

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Speaker 1: That's right. The world can be known, everything can be

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Speaker 1: determined according to general relativity.

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Speaker 3: But then you have quantum mechanics.

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Speaker 1: That's right. And then on the other hand, building from

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Speaker 1: the other side of the ocean, you know, the toaster

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Speaker 1: side of the ocean instead of the microwave side of

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Speaker 1: the ocean, completely mixing metaphors. There is quantum mechanics, and

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Speaker 1: quantum mechanics of course developed in the early part of

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Speaker 1: this century to explain some things that did makes sense.

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Speaker 1: Some experiments we saw which just could not be described

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Speaker 1: using a classical understanding of electromagnetism. It was really what

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Speaker 1: was light that gave us the first clues. We did

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Speaker 1: a whole podcast episode about the photoelectric effect and how

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Speaker 1: we know the photon is a thing, And they did

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Speaker 1: these experiments that just didn't make sense unless you thought

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Speaker 1: of light as being made of tiny little packets of

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Speaker 1: energy rather than a smooth, continuous beam. You had to

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Speaker 1: think about it as these tiny packets.

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Speaker 3: Right when you zoom in. Things don't behave nice and

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Speaker 3: smooth and continuous. They're sort of lumpy and clumpy.

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Speaker 1: Yeah, And there were also just some problems with the theory,

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Speaker 1: like there's a kind of radiation in the universe called

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Speaker 1: black body radiation, which is just how things glow, Like

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Speaker 1: everything in the universe has a temperature and it glows

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Speaker 1: with that.

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Speaker 3: Temperature, and quantum mechanics predicted that well.

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Speaker 1: Classical theory electromagnetism predicted a certain spectrum, like if you're

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Speaker 1: this temperature you should glow with this color. If you're

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Speaker 1: that temperature, you should glow with that other color. The

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Speaker 1: problem was that it predicted that for certain temperatures you

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Speaker 1: should glow at a crazy nonsensical color, like you should

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Speaker 1: get an infinite amount of radiation. The original theory, the

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Speaker 1: one before quantum mechanics, said that things that certain temperatures

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Speaker 1: should have an infinite amount of light at very very

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Speaker 1: low wavelengths. Right, it really really sort of it's called

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Speaker 1: ultraviolet light, that they should have like a ridiculous amount,

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Speaker 1: an infinite amount of ultraviolet light, which is nonsensical.

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Speaker 3: So you can do an experiment basically that proves that

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Speaker 3: general relativity doesn't work for all cases.

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Speaker 1: Well, you can do an experiment that proves that the

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Speaker 1: old theory of electricity and magnetism doesn't work. And we

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Speaker 1: knew that didn't work, where like, Okay, this theory is

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Speaker 1: making a prediction that just doesn't make sense. But if

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Speaker 1: you add quantum mechanics to it, quantum mechanics says, oh,

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Speaker 1: that's just because light is not continuous. If you make

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Speaker 1: light into chunks, then if you predict that, you don't

439
00:21:53,840 --> 00:21:55,959
Speaker 1: see this crazy behavior. And that's in fact what we

440
00:21:56,000 --> 00:21:58,359
Speaker 1: saw in nature, and so we needed to sort of

441
00:21:58,440 --> 00:22:01,200
Speaker 1: change the theory. The theory gave no on sensical results.

442
00:22:01,480 --> 00:22:02,960
Speaker 1: I mean, I have to add this bit to it,

443
00:22:03,440 --> 00:22:06,320
Speaker 1: bit that says, okay, well there's a minimum size to

444
00:22:06,359 --> 00:22:09,560
Speaker 1: a photon, and that solved that problem. It said, okay,

445
00:22:09,600 --> 00:22:13,000
Speaker 1: now you can make realistic predictions. And so but the

446
00:22:13,080 --> 00:22:16,119
Speaker 1: thing to understand is that, like quantum mechanics changes also

447
00:22:16,240 --> 00:22:18,720
Speaker 1: the way we think about the universe. Right, it says

448
00:22:19,000 --> 00:22:21,600
Speaker 1: things are uncertain, things are fluctuating. This is this like

449
00:22:21,880 --> 00:22:24,200
Speaker 1: crazy randomness the heart of the universe.

450
00:22:24,280 --> 00:22:27,359
Speaker 3: All right, So those are the two big titans in

451
00:22:27,400 --> 00:22:31,120
Speaker 3: physics theories, right, general relativity and quantum mechanics that try

452
00:22:31,160 --> 00:22:33,440
Speaker 3: to explain the universe. And the problem is that they

453
00:22:33,520 --> 00:22:36,200
Speaker 3: don't play well together. So let's get into a little

454
00:22:36,200 --> 00:22:38,800
Speaker 3: bit of why they don't play well together and whether

455
00:22:38,920 --> 00:22:42,240
Speaker 3: this idea of loop quantum gravity can help solve that.

456
00:22:42,760 --> 00:22:44,320
Speaker 3: But first, let's take a quick break.

457
00:22:48,800 --> 00:22:51,760
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Speaker 3: All right, Daniel, So general relativity and quantum mechanics don't

506
00:25:30,840 --> 00:25:32,639
Speaker 3: play well together, is it fair to say? Is it

507
00:25:33,000 --> 00:25:34,840
Speaker 3: kind of like I'm trying to think of an analogy.

508
00:25:34,920 --> 00:25:38,320
Speaker 3: Is it kind of like microeconomics and macroeconomics, Like, you know,

509
00:25:38,359 --> 00:25:43,520
Speaker 3: macroeconomics is good for, you know, big economies and countries,

510
00:25:43,600 --> 00:25:47,160
Speaker 3: and microeconomics is good for like how people make decisions,

511
00:25:47,160 --> 00:25:50,640
Speaker 3: but like somehow they don't always. It's weird to think

512
00:25:50,640 --> 00:25:52,119
Speaker 3: about where they meet in the middle.

513
00:25:52,440 --> 00:25:55,840
Speaker 1: Perhaps, but in those two cases, one should be an

514
00:25:55,880 --> 00:25:58,280
Speaker 1: extreme case of the other. Here it's really you have

515
00:25:58,320 --> 00:26:01,560
Speaker 1: a fundamental different view of how the universe works, you know.

516
00:26:01,600 --> 00:26:05,119
Speaker 1: It's more like totally different kinds of art, you know,

517
00:26:05,200 --> 00:26:09,040
Speaker 1: like figurative art versus symbolic art. Like what's a better

518
00:26:09,080 --> 00:26:11,199
Speaker 1: way to like describe the human experience?

519
00:26:11,680 --> 00:26:11,840
Speaker 2: You know?

520
00:26:12,000 --> 00:26:15,679
Speaker 1: Is it through abstracts splashes of color? Or is it

521
00:26:15,720 --> 00:26:18,879
Speaker 1: by you know, depicting the things we see in interesting

522
00:26:18,960 --> 00:26:20,840
Speaker 1: juxtapositions or something I don't know.

523
00:26:21,440 --> 00:26:24,520
Speaker 3: Right, right, it's like a totally lens or you know,

524
00:26:24,720 --> 00:26:25,879
Speaker 3: totally set of glasses.

525
00:26:26,240 --> 00:26:29,120
Speaker 1: Yes, it's a completely different way of thinking about the world.

526
00:26:29,320 --> 00:26:31,720
Speaker 1: And people have been trying for a long time to

527
00:26:31,720 --> 00:26:34,240
Speaker 1: bring them together to say, all right, are these things

528
00:26:34,320 --> 00:26:36,840
Speaker 1: in conflict or can we make a consistent sort of

529
00:26:36,920 --> 00:26:39,679
Speaker 1: quantum theory of gravity that brings it all together?

530
00:26:40,400 --> 00:26:40,600
Speaker 5: Right?

531
00:26:40,640 --> 00:26:43,040
Speaker 3: And so here's Bianca talking about that question.

532
00:26:43,160 --> 00:26:47,560
Speaker 5: It's one of the really big outstanding questions and physics,

533
00:26:47,680 --> 00:26:52,399
Speaker 5: and my view really means quantum gravity should include a

534
00:26:52,440 --> 00:26:55,719
Speaker 5: new notion of space time. We have to replace it, however,

535
00:26:55,760 --> 00:26:59,880
Speaker 5: with something completely new. We expected that the change cry

536
00:27:00,280 --> 00:27:04,920
Speaker 5: dramatically is a foundation so physics and get very interesting

537
00:27:05,320 --> 00:27:08,600
Speaker 5: insights into the nature of space and time.

538
00:27:08,760 --> 00:27:10,960
Speaker 3: All right, So it seems like we need something totally

539
00:27:11,280 --> 00:27:14,280
Speaker 3: new here. And so Daniel, can you explain to me

540
00:27:14,359 --> 00:27:16,600
Speaker 3: kind of what the problem is, like, why can't they

541
00:27:16,720 --> 00:27:18,280
Speaker 3: play well together the ones that we have.

542
00:27:18,480 --> 00:27:20,440
Speaker 1: Well, people have been trying to bring these two things

543
00:27:20,440 --> 00:27:23,200
Speaker 1: together since basically they've existed. You know, people have been

544
00:27:23,240 --> 00:27:26,960
Speaker 1: working on making gravity into a quantum theory for a

545
00:27:27,040 --> 00:27:30,359
Speaker 1: very very long time. But you know, quantum theories traditionally

546
00:27:30,359 --> 00:27:33,280
Speaker 1: thinking about forces very differently than gravity does. They think

547
00:27:33,320 --> 00:27:37,399
Speaker 1: about forces as like ripples in a quantum field. You know,

548
00:27:37,400 --> 00:27:40,320
Speaker 1: you have like the electromagnetic field, and you think about

549
00:27:40,720 --> 00:27:44,640
Speaker 1: how do photons communicate the electromagnetic field. There are ripples

550
00:27:44,680 --> 00:27:48,400
Speaker 1: in this electromagnetic field, and you quantize those ripples. That's

551
00:27:48,400 --> 00:27:50,400
Speaker 1: how quantum mechanics thinks about forces.

552
00:27:50,480 --> 00:27:52,919
Speaker 3: But in general relativity, a force is really more like

553
00:27:52,960 --> 00:27:53,919
Speaker 3: a bending out space.

554
00:27:54,200 --> 00:27:57,200
Speaker 1: That's right, And mostly you can do this. You could say, like,

555
00:27:57,240 --> 00:27:59,719
Speaker 1: all right, well, can I make a quantum theory of gravity?

556
00:27:59,720 --> 00:28:02,960
Speaker 1: Can I build a theory where I exchange where gravity

557
00:28:03,280 --> 00:28:06,040
Speaker 1: is a field and it has ripples and those ripples

558
00:28:06,080 --> 00:28:09,760
Speaker 1: are quantized, just like I can for electromagnetism, And mostly

559
00:28:09,800 --> 00:28:13,199
Speaker 1: you can, actually you can. It's mostly it works, but

560
00:28:13,359 --> 00:28:15,040
Speaker 1: it fails in some moments.

561
00:28:15,119 --> 00:28:18,720
Speaker 3: Couldn't you just have quantum fields in a general relativity

562
00:28:19,160 --> 00:28:22,840
Speaker 3: you know world, you know, like, couldn't you have quantum

563
00:28:22,880 --> 00:28:26,119
Speaker 3: particles that bend space as well? Like why can't a

564
00:28:26,400 --> 00:28:29,199
Speaker 3: quantum particle also bend space like a planet?

565
00:28:29,320 --> 00:28:31,919
Speaker 1: Well, but then gravity is coming from something that's classical

566
00:28:32,000 --> 00:28:36,000
Speaker 1: that's smooth and continuous, and general relativity is just not

567
00:28:36,080 --> 00:28:39,720
Speaker 1: a quantum theory, right, Like it assumes that you know

568
00:28:40,320 --> 00:28:43,360
Speaker 1: everything about the location and the time and the position.

569
00:28:43,600 --> 00:28:46,520
Speaker 3: Well, couldn't you just make the bending also kind of uncertain?

570
00:28:46,560 --> 00:28:49,240
Speaker 3: I'm just trying to figure out why why you can't

571
00:28:49,240 --> 00:28:51,480
Speaker 3: marry the two, you know, why can't these particles and

572
00:28:51,520 --> 00:28:54,760
Speaker 3: these fields exist in a world that is as Einstein

573
00:28:55,400 --> 00:28:57,680
Speaker 3: envisioned it with the bending and the gravity.

574
00:28:57,960 --> 00:29:00,880
Speaker 1: That's exactly what Luke, quant gravity is. You just basically

575
00:29:00,960 --> 00:29:03,200
Speaker 1: invented the idea for the gravity right.

576
00:29:04,600 --> 00:29:06,880
Speaker 3: Right now, Thank you very much.

577
00:29:07,800 --> 00:29:10,680
Speaker 1: That's right. And you know this other idea is like,

578
00:29:10,800 --> 00:29:13,280
Speaker 1: let's take the gravitational field and think about it as

579
00:29:13,320 --> 00:29:16,640
Speaker 1: a quantum field that mostly works. The important thing to

580
00:29:16,720 --> 00:29:19,840
Speaker 1: understand is that it only fails when gravity gets really

581
00:29:19,920 --> 00:29:24,040
Speaker 1: really strong, right, things like inside a black hole. And

582
00:29:24,200 --> 00:29:27,960
Speaker 1: what happens is that it makes nonsense predictions like it

583
00:29:28,320 --> 00:29:30,880
Speaker 1: just like we saw for the black body radiation. It

584
00:29:30,920 --> 00:29:34,000
Speaker 1: predicts like infinite amount of energy will be released, But

585
00:29:34,080 --> 00:29:36,080
Speaker 1: we know that's not true. We know it doesn't happen,

586
00:29:36,480 --> 00:29:40,360
Speaker 1: and so the theories work except in extreme circumstances. And

587
00:29:40,400 --> 00:29:43,560
Speaker 1: that's what makes it really hard. Is like, it's easy

588
00:29:43,600 --> 00:29:45,920
Speaker 1: to fix a theory when you can see it breaking

589
00:29:46,280 --> 00:29:49,160
Speaker 1: that these theories general relativity and quantum mechanics, they only

590
00:29:49,200 --> 00:29:51,800
Speaker 1: disagree about, like what happens at the inside of a

591
00:29:51,840 --> 00:29:54,360
Speaker 1: black hole? And we can't see that.

592
00:29:54,480 --> 00:29:56,280
Speaker 3: Why don't we just ignore black hole? If we just

593
00:29:56,400 --> 00:29:59,080
Speaker 3: ignore black holes in the universe, wouldn't that make our

594
00:29:59,120 --> 00:30:03,400
Speaker 3: lives a lot? Wouldn't that make physics a little bit easier,

595
00:30:03,440 --> 00:30:05,440
Speaker 3: you know, because it's all it seems like, it seems

596
00:30:05,480 --> 00:30:07,440
Speaker 3: like everything breaks in a black hole, and so why

597
00:30:07,440 --> 00:30:09,280
Speaker 3: don't It's like, you know, the mess in my closet,

598
00:30:09,360 --> 00:30:10,280
Speaker 3: let's just ignore it.

599
00:30:10,280 --> 00:30:13,120
Speaker 1: It's the engineering in you, man, that's the engineering the

600
00:30:13,160 --> 00:30:16,120
Speaker 1: scientist in me is desperate to know. I have to

601
00:30:16,160 --> 00:30:19,600
Speaker 1: know it on inside a black hole? Yes, have you

602
00:30:19,600 --> 00:30:21,320
Speaker 1: created a black hole in your closet? Because if so,

603
00:30:21,400 --> 00:30:23,000
Speaker 1: I'm coming over and I want to check it out.

604
00:30:23,440 --> 00:30:25,920
Speaker 3: I think we're close to the singularity, to be honest,

605
00:30:26,320 --> 00:30:28,160
Speaker 3: in there, you don't want to go in there that

606
00:30:28,200 --> 00:30:29,280
Speaker 3: you may never come out, like.

607
00:30:29,240 --> 00:30:32,320
Speaker 1: You have all these rejected toaster microwave protypes in.

608
00:30:32,280 --> 00:30:37,720
Speaker 3: There, that's right, all these rejected app ideas as well.

609
00:30:38,240 --> 00:30:41,160
Speaker 1: And so these two things aren't working together. Well, people

610
00:30:41,160 --> 00:30:44,200
Speaker 1: have tried, but they just give nonsense predictions, like the

611
00:30:44,240 --> 00:30:47,200
Speaker 1: calculations you get suggest, you know, infinite amount of energy

612
00:30:47,440 --> 00:30:50,160
Speaker 1: in a radiated inside a black hole when gravity gets

613
00:30:50,200 --> 00:30:52,520
Speaker 1: really strong, and we can't easily test that because we

614
00:30:52,560 --> 00:30:54,600
Speaker 1: don't have a black hole and I don't have a

615
00:30:54,640 --> 00:30:58,000
Speaker 1: galaxy sized particle collider. I would need to create the

616
00:30:58,040 --> 00:31:01,520
Speaker 1: sort of energy density in order to break quantum gravity.

617
00:31:01,800 --> 00:31:03,560
Speaker 1: And so what we need is we need to see

618
00:31:03,640 --> 00:31:06,160
Speaker 1: inside a black hole, or we need a new idea,

619
00:31:06,280 --> 00:31:09,240
Speaker 1: and so we need Orges vision of quantum gravity.

620
00:31:10,160 --> 00:31:12,920
Speaker 3: I have an idea. How about something called loop quantum gravity.

621
00:31:13,600 --> 00:31:15,040
Speaker 1: That's such a great name too.

622
00:31:16,440 --> 00:31:18,600
Speaker 3: All right, So we have these two force area theories

623
00:31:18,720 --> 00:31:22,560
Speaker 3: and you know, one of them has a thunderbolt cable

624
00:31:23,160 --> 00:31:27,240
Speaker 3: connector and the other side is a mini USB cable connector,

625
00:31:27,240 --> 00:31:29,880
Speaker 3: and so they don't fit. And so that's what this

626
00:31:29,920 --> 00:31:32,000
Speaker 3: idea of loop quantum gravity is. It's like, maybe it's

627
00:31:32,000 --> 00:31:34,000
Speaker 3: like an adapter. That is it like an adapter that

628
00:31:34,080 --> 00:31:36,040
Speaker 3: makes it to work or is it a totally new

629
00:31:36,160 --> 00:31:37,040
Speaker 3: cabling system.

630
00:31:37,320 --> 00:31:40,440
Speaker 1: Yeah, it says instead of trying to think of gravity

631
00:31:40,440 --> 00:31:45,880
Speaker 1: as like a Newtonian gravity as a force and quantizing

632
00:31:45,920 --> 00:31:49,920
Speaker 1: that gravitational field directly. Instead take Orges idea, which is

633
00:31:50,240 --> 00:31:53,840
Speaker 1: just takes space itself and quantize that and say, well,

634
00:31:54,280 --> 00:31:57,960
Speaker 1: maybe general relativity is basically right, except that instead of

635
00:31:57,960 --> 00:32:00,960
Speaker 1: working on a smooth, continuous space, we work on a

636
00:32:01,000 --> 00:32:05,280
Speaker 1: space that is quantized, like there are pixels of space.

637
00:32:05,560 --> 00:32:08,200
Speaker 1: Instead of space being infinite and smooth, there are like

638
00:32:08,480 --> 00:32:09,920
Speaker 1: little chunks of space.

639
00:32:10,160 --> 00:32:13,640
Speaker 3: It would explain how quantum particles move, or it would

640
00:32:13,680 --> 00:32:16,600
Speaker 3: explain how gravity can be quantized.

641
00:32:16,760 --> 00:32:18,959
Speaker 1: It would allow us to build a theory of quantum

642
00:32:19,000 --> 00:32:23,040
Speaker 1: gravity that doesn't make nonsense predictions, because it basically makes

643
00:32:23,480 --> 00:32:28,200
Speaker 1: the places where those predictions get nonsense impossible, like the

644
00:32:28,240 --> 00:32:31,640
Speaker 1: predictions of quantum gravity break down at really high energies

645
00:32:31,720 --> 00:32:34,760
Speaker 1: and really small distances. So the idea is basically, well,

646
00:32:34,800 --> 00:32:37,880
Speaker 1: what if really small distances aren't allowed, like there's just

647
00:32:38,040 --> 00:32:40,600
Speaker 1: nothing smaller than ten to the minus thirty five where

648
00:32:40,600 --> 00:32:43,160
Speaker 1: things break down, then there isn't a problem.

649
00:32:43,240 --> 00:32:47,200
Speaker 3: Let's just ignore the closet and assume that a closet

650
00:32:47,240 --> 00:32:49,920
Speaker 3: is Quanti said, it's just one thing.

651
00:32:51,000 --> 00:32:53,880
Speaker 1: I see. Yeah, it's not ignoring the closet, it's saying

652
00:32:54,040 --> 00:32:56,560
Speaker 1: the closet doesn't exist. You were so worried about the closet.

653
00:32:56,560 --> 00:32:59,360
Speaker 1: It turns out it's impossible. There is no closet.

654
00:33:00,000 --> 00:33:02,920
Speaker 3: Sounds like you're trying to make gravity quantized. You're not

655
00:33:03,000 --> 00:33:07,160
Speaker 3: trying to make quantum things the bendy like space.

656
00:33:07,400 --> 00:33:11,240
Speaker 1: Well, if space is bendy and quantized, then yeah, quantum

657
00:33:11,280 --> 00:33:14,320
Speaker 1: things move through quantized bend bendy space.

658
00:33:14,640 --> 00:33:17,160
Speaker 3: Oh so this would allow you to bend space in

659
00:33:17,200 --> 00:33:18,160
Speaker 3: a quantized way.

660
00:33:18,520 --> 00:33:20,320
Speaker 1: Yeah, it would allow you to bend space in a

661
00:33:20,400 --> 00:33:23,880
Speaker 1: quantized way. And it's kind of a beautiful idea because

662
00:33:23,880 --> 00:33:27,120
Speaker 1: it's very similar to the origin of quantum mechanics itself. Right,

663
00:33:27,480 --> 00:33:29,920
Speaker 1: we solve the problem of black body radiation, of this

664
00:33:30,200 --> 00:33:33,880
Speaker 1: thermal emission giving crazy numbers by saying, oh, maybe we

665
00:33:33,880 --> 00:33:38,560
Speaker 1: can just quantize photons, and that mathematically solves that problem. Here,

666
00:33:38,880 --> 00:33:42,080
Speaker 1: we're solving the problem of infinite emissions inside black holes

667
00:33:42,120 --> 00:33:45,440
Speaker 1: and really high energies and small distances by saying, oh,

668
00:33:45,520 --> 00:33:49,080
Speaker 1: maybe we quantize space and so those small distances are impossible.

669
00:33:49,320 --> 00:33:52,600
Speaker 1: So there's a beautiful sort of analogy there to previous

670
00:33:52,840 --> 00:33:56,360
Speaker 1: structures of solutions that suggest like tentatively like ooh, maybe

671
00:33:56,360 --> 00:33:57,240
Speaker 1: this is the right.

672
00:33:57,120 --> 00:34:00,960
Speaker 3: Track because it feels like nineteen fifteen a little bit.

673
00:34:01,800 --> 00:34:04,360
Speaker 1: That's right. We're going to party like it's nineteen nineteen.

674
00:34:04,680 --> 00:34:07,920
Speaker 3: Yeah, people are growing mustaches and wearing top hats, and

675
00:34:07,960 --> 00:34:08,839
Speaker 3: you're like, I like it.

676
00:34:08,960 --> 00:34:11,239
Speaker 1: I like it except for the fact that, like, no

677
00:34:11,320 --> 00:34:14,120
Speaker 1: women are allowed to do physics back then. No, No,

678
00:34:14,360 --> 00:34:15,960
Speaker 1: that's the bad part, all right.

679
00:34:16,000 --> 00:34:18,880
Speaker 3: So the idea is that maybe space and time itself

680
00:34:19,160 --> 00:34:21,839
Speaker 3: like space and time like, there are no there's no

681
00:34:21,920 --> 00:34:24,560
Speaker 3: there's no infinite as at least small second.

682
00:34:24,800 --> 00:34:26,880
Speaker 1: That's right, And that's a question people have been sending

683
00:34:26,920 --> 00:34:29,920
Speaker 1: me over email many times. If you quantize space, you

684
00:34:30,120 --> 00:34:34,080
Speaker 1: also quantize time. And you know, space time is a

685
00:34:34,160 --> 00:34:37,400
Speaker 1: fabric in this theory and they're deeply connected. And so

686
00:34:37,480 --> 00:34:41,080
Speaker 1: if you're quantizing space, then yes, they're also probably quantizing time.

687
00:34:41,320 --> 00:34:43,520
Speaker 3: Well, it's like you're there's actually a ticking clock to

688
00:34:43,560 --> 00:34:44,040
Speaker 3: the universe.

689
00:34:44,080 --> 00:34:47,920
Speaker 1: Maybe, yeah, there's a minimum time that makes sense. You know,

690
00:34:47,960 --> 00:34:52,080
Speaker 1: you can't infinitely divide a second into arbitrarily tiny slices.

691
00:34:52,239 --> 00:34:54,960
Speaker 1: There's a minimumount of time below, which makes no sense.

692
00:34:55,239 --> 00:34:57,240
Speaker 3: Okay, and so what does that mean? I guess space

693
00:34:57,560 --> 00:35:02,160
Speaker 3: is not really like space. Space is more like a

694
00:35:02,239 --> 00:35:03,719
Speaker 3: clump of little spaces.

695
00:35:03,840 --> 00:35:06,319
Speaker 1: Well, the reason it's called loop quantum gravity is that

696
00:35:06,360 --> 00:35:08,560
Speaker 1: the way to think about it is that space is

697
00:35:08,600 --> 00:35:10,680
Speaker 1: a bunch of these little loops and they're sort of

698
00:35:10,760 --> 00:35:14,760
Speaker 1: woven together. And so think about space is like chain mail.

699
00:35:14,800 --> 00:35:17,480
Speaker 1: If you're into D and D, you know, it's like

700
00:35:17,520 --> 00:35:20,319
Speaker 1: a bunch of links that are all connected to each other.

701
00:35:20,360 --> 00:35:24,040
Speaker 1: And space comes out of that, right spaces, there are

702
00:35:24,080 --> 00:35:27,200
Speaker 1: these The fundamental thing in the universe are these little loops,

703
00:35:27,480 --> 00:35:30,200
Speaker 1: and the loops are woven together. And the way that

704
00:35:30,480 --> 00:35:33,640
Speaker 1: things move through space, and the way that gravity happens

705
00:35:33,920 --> 00:35:36,120
Speaker 1: is how these little loops interact with each other and

706
00:35:36,200 --> 00:35:38,640
Speaker 1: pull on each other and are built together.

707
00:35:39,120 --> 00:35:41,600
Speaker 3: To what are these little loops? They're like little bits

708
00:35:41,640 --> 00:35:42,440
Speaker 3: of the universe.

709
00:35:42,560 --> 00:35:45,239
Speaker 1: That's the next Nobel prize. Man, you want to win

710
00:35:45,280 --> 00:35:46,399
Speaker 1: two Nobel Prizes and.

711
00:35:46,360 --> 00:35:48,520
Speaker 3: A single podcast in a single let's do it.

712
00:35:48,840 --> 00:35:50,640
Speaker 1: You have enough come for this to be a physicist.

713
00:35:50,960 --> 00:35:53,840
Speaker 3: So for the what do you call the hat the

714
00:35:54,120 --> 00:35:54,759
Speaker 3: hat trick, A.

715
00:35:54,760 --> 00:35:57,080
Speaker 1: Hat trick, You're going to go for three Nobel prizes.

716
00:35:57,600 --> 00:35:59,399
Speaker 3: That's when you go, yeah, fifteen minutes left.

717
00:36:00,400 --> 00:36:03,839
Speaker 1: That's when you invent the perfect toaster. Microwave combination that

718
00:36:03,920 --> 00:36:06,160
Speaker 1: definitely is worth a Nobel Prize. Well, nobody knows what

719
00:36:06,200 --> 00:36:08,279
Speaker 1: these loops are, and you know that's sort of the

720
00:36:08,320 --> 00:36:11,399
Speaker 1: next question, Like if you can start from these little

721
00:36:11,440 --> 00:36:15,000
Speaker 1: loops and build a theory that describes everything and predicts

722
00:36:15,000 --> 00:36:17,360
Speaker 1: the universe and it is consistent with everything we know,

723
00:36:17,840 --> 00:36:20,120
Speaker 1: then the next question is you're like, well, why these

724
00:36:20,160 --> 00:36:22,279
Speaker 1: little loops? What do they mean? How do we get

725
00:36:22,280 --> 00:36:24,360
Speaker 1: those little loops right? Where do they come from? Do

726
00:36:24,360 --> 00:36:27,360
Speaker 1: they emerge from something deeper? You know, physicists are great

727
00:36:27,400 --> 00:36:30,480
Speaker 1: at making answers that create more questions.

728
00:36:30,680 --> 00:36:33,240
Speaker 3: But I guess why call them loops? Are they actually

729
00:36:33,280 --> 00:36:35,800
Speaker 3: like little rings that are tied together?

730
00:36:35,960 --> 00:36:36,360
Speaker 4: What is it?

731
00:36:36,480 --> 00:36:41,000
Speaker 3: Why not call them? I don't know, bubbles or pixels

732
00:36:41,120 --> 00:36:42,880
Speaker 3: or you know what I mean, Like, what is it

733
00:36:42,960 --> 00:36:44,960
Speaker 3: about the idea of a loop that gives it the

734
00:36:45,000 --> 00:36:46,200
Speaker 3: name loop quantum gravity?

735
00:36:46,440 --> 00:36:48,399
Speaker 1: Well, I guess bubbles would work also, but I think

736
00:36:48,440 --> 00:36:50,680
Speaker 1: it's just a visualization idea. You know that these things

737
00:36:50,680 --> 00:36:54,680
Speaker 1: are linked together in a sort of a mesh, and

738
00:36:54,760 --> 00:36:57,160
Speaker 1: you know there are also loops, Like we're doing calculations

739
00:36:57,440 --> 00:37:00,279
Speaker 1: around in a circle, but you have to avoid sort

740
00:37:00,280 --> 00:37:02,760
Speaker 1: of trap, like you can't think about these as loops

741
00:37:02,880 --> 00:37:08,080
Speaker 1: in space. They're not like circles on some axis, right,

742
00:37:08,120 --> 00:37:10,200
Speaker 1: because then you have what is that axis? We're talking

743
00:37:10,200 --> 00:37:13,640
Speaker 1: about the very nature of space itself. It's not like

744
00:37:13,680 --> 00:37:16,279
Speaker 1: these loops are somewhere and like this loop is at

745
00:37:16,280 --> 00:37:18,960
Speaker 1: this point and that loop is at that point. The

746
00:37:19,040 --> 00:37:22,319
Speaker 1: loops are the points like space is these this thing

747
00:37:22,360 --> 00:37:25,200
Speaker 1: we're talking about like the nature of space itself, which

748
00:37:25,239 --> 00:37:27,360
Speaker 1: is really hard to sort of wrap your mind around.

749
00:37:27,680 --> 00:37:29,640
Speaker 3: Oh, I see, you were just looking at you guys

750
00:37:29,640 --> 00:37:33,279
Speaker 3: were just looking for like a word that implies that

751
00:37:33,920 --> 00:37:36,239
Speaker 3: space is made up of little things that are kind

752
00:37:36,239 --> 00:37:41,600
Speaker 3: of interconnected or overlapping, right, or like hooked together. M okay,

753
00:37:41,600 --> 00:37:44,400
Speaker 3: And so you went with them loops. I was like,

754
00:37:44,480 --> 00:37:47,040
Speaker 3: they went with loops.

755
00:37:47,239 --> 00:37:49,319
Speaker 1: I think it's not a terrible idea. You know, they

756
00:37:49,360 --> 00:37:54,000
Speaker 1: could have called it the bubble quantum gravity but or

757
00:37:54,040 --> 00:37:56,640
Speaker 1: full it. But you know, we talked about this another

758
00:37:56,680 --> 00:37:58,560
Speaker 1: time in the podcast. You can think of these things

759
00:37:58,600 --> 00:38:01,040
Speaker 1: as little bubbles and you get to talk about things

760
00:38:01,080 --> 00:38:04,759
Speaker 1: like space foam and quantum foam. Because these loops aren't fixed, right,

761
00:38:04,840 --> 00:38:07,320
Speaker 1: they can like fluctuate in and out of existence.

762
00:38:07,680 --> 00:38:10,800
Speaker 3: I see. So these are all related ideas loop quantum gravity,

763
00:38:10,880 --> 00:38:14,840
Speaker 3: spacefoam quantum foam. They're all sort of coming at this

764
00:38:14,960 --> 00:38:16,439
Speaker 3: idea of a bubbly.

765
00:38:16,120 --> 00:38:20,520
Speaker 1: Space, yeah, and thinking about space not as continuous and smooth,

766
00:38:20,560 --> 00:38:23,279
Speaker 1: but if made up of little quantized bits, like, let's

767
00:38:23,360 --> 00:38:27,279
Speaker 1: quantize space itself, because general relativity is an attempt to

768
00:38:27,360 --> 00:38:30,400
Speaker 1: understand gravity in terms of the nature of space. And

769
00:38:30,440 --> 00:38:32,680
Speaker 1: so if we're going to get a quantum theory of gravity,

770
00:38:32,719 --> 00:38:35,719
Speaker 1: the idea is, let's just quantize space itself, all.

771
00:38:35,760 --> 00:38:39,680
Speaker 3: Right, So that's quantum or loop quantum gravity. And so

772
00:38:39,800 --> 00:38:42,680
Speaker 3: we'll get into what are some of the open questions

773
00:38:42,680 --> 00:38:44,920
Speaker 3: and why people think it may or may not be

774
00:38:45,040 --> 00:38:48,279
Speaker 3: the ultimate answer to how the universe works. But first,

775
00:38:48,360 --> 00:38:49,400
Speaker 3: let's take a quick break.

776
00:38:53,960 --> 00:38:55,759
Speaker 1: When you pop a piece of cheese into your mouth

777
00:38:55,880 --> 00:38:59,000
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778
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779
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780
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781
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782
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783
00:39:15,120 --> 00:39:19,359
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784
00:39:19,400 --> 00:39:22,480
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785
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786
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787
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788
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789
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790
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791
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792
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794
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795
00:39:52,920 --> 00:39:56,560
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Speaker 3: Okay, Donnie, what does it all mean? What does loop

819
00:41:17,880 --> 00:41:21,880
Speaker 3: quantum gravity mean if it's true or if it's not true?

820
00:41:22,320 --> 00:41:24,719
Speaker 3: And why do we think it might not be true?

821
00:41:24,760 --> 00:41:27,600
Speaker 1: All right, Well, here's the big letdown. Right, So, so

822
00:41:27,680 --> 00:41:28,360
Speaker 1: far it seems like.

823
00:41:28,400 --> 00:41:29,200
Speaker 3: You're going to break the loop.

824
00:41:29,320 --> 00:41:30,960
Speaker 1: I'm going to break the loop. Yeah. It seems like

825
00:41:31,000 --> 00:41:34,000
Speaker 1: a beautiful idea. It seems really promising. It seems like

826
00:41:34,200 --> 00:41:37,080
Speaker 1: dot dot dot the next obvious step in physics. Right.

827
00:41:37,600 --> 00:41:40,239
Speaker 1: The problem is there's a lot of problems with it,

828
00:41:40,560 --> 00:41:42,640
Speaker 1: and there's a lot of open questions. And that doesn't

829
00:41:42,640 --> 00:41:44,640
Speaker 1: mean it's not going to work. It just means it's

830
00:41:44,680 --> 00:41:46,919
Speaker 1: far from clear that it is going to work.

831
00:41:47,160 --> 00:41:49,279
Speaker 3: Oh, I see, there's a room for skepticism.

832
00:41:49,520 --> 00:41:53,319
Speaker 1: Yeah, and even among physicists there's a lot of skepticism

833
00:41:53,480 --> 00:41:56,480
Speaker 1: about loop quantum gravity. It's a bit of a fringe theory.

834
00:41:56,760 --> 00:41:58,640
Speaker 1: There are a lot more people working, for example, on

835
00:41:58,760 --> 00:42:02,560
Speaker 1: string theory, which is a completely different attempt to unify

836
00:42:02,760 --> 00:42:06,040
Speaker 1: gravity and quantum mechanics and all of the other forces

837
00:42:06,280 --> 00:42:08,880
Speaker 1: all at once. String theory is like a theory of everything,

838
00:42:09,160 --> 00:42:11,759
Speaker 1: whereas Looke quantum gravity is like, let's just focus on

839
00:42:11,920 --> 00:42:13,800
Speaker 1: making gravity a quantum theory.

840
00:42:13,960 --> 00:42:16,040
Speaker 3: If you can do that, then that's another way to

841
00:42:16,120 --> 00:42:17,880
Speaker 3: unify these two big theories.

842
00:42:18,280 --> 00:42:20,799
Speaker 1: Yeah, so string theory is sort of a The other

843
00:42:21,000 --> 00:42:24,360
Speaker 1: idea is the opponent of Luke quantum gravity.

844
00:42:24,880 --> 00:42:27,480
Speaker 3: Let's build a tunnel under the Atlantic instead of trying

845
00:42:27,480 --> 00:42:28,720
Speaker 3: to make these two bridges work.

846
00:42:29,080 --> 00:42:31,840
Speaker 1: And string theory is a much bigger community, has a

847
00:42:31,840 --> 00:42:34,000
Speaker 1: lot more people working on it, people are sort of

848
00:42:34,040 --> 00:42:36,400
Speaker 1: more excited about it, whereas Looke quantum gravity is like,

849
00:42:36,719 --> 00:42:39,960
Speaker 1: you know, the younger sibling in terms of theories of

850
00:42:40,040 --> 00:42:41,160
Speaker 1: quantum gravity.

851
00:42:40,960 --> 00:42:43,640
Speaker 3: The underdog, exactly making me like it more now.

852
00:42:45,120 --> 00:42:47,839
Speaker 1: And one reason is that it sort of hasn't yet

853
00:42:47,880 --> 00:42:50,400
Speaker 1: delivered on its promise. Like, what you want to do

854
00:42:50,560 --> 00:42:53,560
Speaker 1: is start from this concept of loops and from it

855
00:42:53,600 --> 00:42:57,160
Speaker 1: should emerge Einstein's theory of relativity. You should be like,

856
00:42:57,239 --> 00:42:59,240
Speaker 1: I'm gonna have a completely different picture of the world,

857
00:42:59,680 --> 00:43:02,440
Speaker 1: but it's going to give the same predictions sort of

858
00:43:02,600 --> 00:43:05,359
Speaker 1: at my scale. You should still describe how a ball

859
00:43:05,400 --> 00:43:10,120
Speaker 1: flies over my neighbor's wall and how and gravitational waves

860
00:43:10,120 --> 00:43:11,640
Speaker 1: and all of that stuff. You should be able to

861
00:43:11,680 --> 00:43:14,400
Speaker 1: sort of start from there and build up to general relativity.

862
00:43:14,560 --> 00:43:17,319
Speaker 3: You start off imagining the world. The universe is a

863
00:43:17,600 --> 00:43:22,800
Speaker 3: measure of loops, but it doesn't give you baseballs and fences.

864
00:43:22,880 --> 00:43:25,520
Speaker 1: Yeah, not yet. And it's not like they can't do it.

865
00:43:25,520 --> 00:43:27,680
Speaker 1: It's just like, well, they haven't quite figured it out yet,

866
00:43:28,000 --> 00:43:31,760
Speaker 1: and it's hard, right, These are difficult things, and people

867
00:43:31,880 --> 00:43:35,359
Speaker 1: are hacking with their machetes through the jungle of mathematics

868
00:43:35,360 --> 00:43:37,799
Speaker 1: that's involved, and it's not always clear that we have

869
00:43:37,840 --> 00:43:40,799
Speaker 1: the right tools. And sometimes progress has paused for like

870
00:43:40,920 --> 00:43:44,359
Speaker 1: a decade or thirty years until somebody's like, hey, we've

871
00:43:44,400 --> 00:43:47,080
Speaker 1: heard this new idea from mathematics. Turns out that's exactly

872
00:43:47,080 --> 00:43:48,960
Speaker 1: what we need over here. That kind of thing has

873
00:43:48,960 --> 00:43:51,080
Speaker 1: happened in physics a lot, a lot of times. And

874
00:43:51,200 --> 00:43:53,640
Speaker 1: there are other sort of really interesting problems with loop

875
00:43:53,680 --> 00:43:56,960
Speaker 1: quantum gravity which actually conflict with relativity.

876
00:43:57,080 --> 00:43:59,560
Speaker 3: Okay, so there's maybe something fundamentally wrong here.

877
00:44:00,120 --> 00:44:02,640
Speaker 1: Are not necessarily wrong, but it would again change the

878
00:44:02,680 --> 00:44:05,520
Speaker 1: way we think about the universe. Like, here's the problem

879
00:44:05,560 --> 00:44:09,919
Speaker 1: with quantizing space. Say there are space pixels, right, that

880
00:44:10,000 --> 00:44:12,719
Speaker 1: means that in some sense there's a minimum distance to

881
00:44:12,760 --> 00:44:16,719
Speaker 1: the universe. But what is that distance? Because we know

882
00:44:16,840 --> 00:44:21,200
Speaker 1: that distances depend on velocities, right, Like, as you move faster,

883
00:44:21,560 --> 00:44:25,279
Speaker 1: things get shrunk. So do things that are moving see

884
00:44:25,440 --> 00:44:30,120
Speaker 1: smaller space pixels than things that are stationary, And if so,

885
00:44:30,880 --> 00:44:33,120
Speaker 1: it would mean that there is some sort of absolute

886
00:44:33,160 --> 00:44:35,839
Speaker 1: velocity to the universe. Right, if you can measure your

887
00:44:35,840 --> 00:44:38,799
Speaker 1: space pixel the size of your space pixels, that tells

888
00:44:38,800 --> 00:44:41,760
Speaker 1: you sort of what your absolute speed is. But special

889
00:44:41,800 --> 00:44:45,359
Speaker 1: relativity has always told us velocities relative. There is no

890
00:44:45,480 --> 00:44:48,719
Speaker 1: absolute frame, and so this would sort of conflict with

891
00:44:48,800 --> 00:44:52,120
Speaker 1: a really really core concept in special relativity.

892
00:44:52,400 --> 00:44:54,680
Speaker 3: Couldn't it be like the speed of light, which like

893
00:44:54,760 --> 00:44:57,439
Speaker 3: it always looks the same no matter how fast you're going.

894
00:44:57,440 --> 00:44:59,759
Speaker 3: Couldn't these loops always look the same no matter how

895
00:44:59,800 --> 00:45:00,560
Speaker 3: fa you're going.

896
00:45:00,920 --> 00:45:02,600
Speaker 1: Yeah, So there's a lot of ways to try to

897
00:45:02,640 --> 00:45:05,400
Speaker 1: solve this problem. One is to say, you know, we

898
00:45:05,480 --> 00:45:09,320
Speaker 1: have these weird space pixels which to form under certain circumstances,

899
00:45:09,400 --> 00:45:13,480
Speaker 1: and there's some very complicated mathematics involved to do essentially

900
00:45:13,520 --> 00:45:15,560
Speaker 1: what you just described. You're really hidden out of the

901
00:45:15,600 --> 00:45:16,759
Speaker 1: park today with like.

902
00:45:16,640 --> 00:45:18,799
Speaker 3: I'm glad for def going for the hat trick here,

903
00:45:18,960 --> 00:45:21,400
Speaker 3: brilliant physics. Wait wait till you see why what I

904
00:45:21,480 --> 00:45:22,720
Speaker 3: pull out at the last five minutes.

905
00:45:23,040 --> 00:45:25,560
Speaker 1: And the other is to accept it and to say, hm,

906
00:45:25,760 --> 00:45:28,279
Speaker 1: you know what, maybe there is maybe there is an

907
00:45:28,320 --> 00:45:32,320
Speaker 1: absolute reference frame. Maybe special relativity is slightly.

908
00:45:31,880 --> 00:45:36,560
Speaker 3: Wrong, But wouldn't that throw the whole light speed thing off.

909
00:45:36,719 --> 00:45:39,120
Speaker 1: Well, not all of special relativity has to be wrong.

910
00:45:39,280 --> 00:45:42,759
Speaker 1: The consequence would be that light would travel at a

911
00:45:42,800 --> 00:45:47,040
Speaker 1: slightly different speed as a function of its frequency. So

912
00:45:47,160 --> 00:45:50,040
Speaker 1: like high frequency light would travel that is slightly different

913
00:45:50,080 --> 00:45:53,200
Speaker 1: speed from lower frequency light like X rays and UV

914
00:45:53,360 --> 00:45:57,800
Speaker 1: light would move faster than radio waves. But it'd be

915
00:45:57,840 --> 00:46:00,600
Speaker 1: a really small difference. It'd be really hard.

916
00:46:00,400 --> 00:46:03,040
Speaker 3: To tell, all right, So there's some skepticism, or I

917
00:46:03,040 --> 00:46:05,719
Speaker 3: guess some open questions about it, because it's not quite

918
00:46:06,000 --> 00:46:09,080
Speaker 3: hitting it out of the ballpark, over your fence or not,

919
00:46:09,680 --> 00:46:14,320
Speaker 3: into your neighbor's house or not. And so I guess

920
00:46:14,560 --> 00:46:16,680
Speaker 3: the question is what does it all mean? I mean,

921
00:46:16,760 --> 00:46:19,239
Speaker 3: what if it happens to be true? And how are

922
00:46:19,239 --> 00:46:21,720
Speaker 3: we even going to know if something like this is true?

923
00:46:21,840 --> 00:46:25,200
Speaker 1: Yeah, so, of course the deep question I have is

924
00:46:25,239 --> 00:46:27,200
Speaker 1: what does this mean for the nature of the universe?

925
00:46:27,280 --> 00:46:29,560
Speaker 1: And how could we see it? Right? Where would it

926
00:46:29,600 --> 00:46:32,000
Speaker 1: manifest itself? And as we talked about in the beginning

927
00:46:32,000 --> 00:46:35,200
Speaker 1: of the episode, the place this would really be important,

928
00:46:35,200 --> 00:46:37,200
Speaker 1: the place you would notice it difference, the place where

929
00:46:37,239 --> 00:46:39,960
Speaker 1: it matters is inside a black hole.

930
00:46:40,000 --> 00:46:43,879
Speaker 3: Of course, of course. Right, So let's go there, Let's

931
00:46:43,920 --> 00:46:44,680
Speaker 3: go into the closet.

932
00:46:44,760 --> 00:46:46,839
Speaker 1: Dan, that's right, we're opening the closet and all.

933
00:46:48,960 --> 00:46:51,520
Speaker 3: Who knows what's in there and who knows what's been growing?

934
00:46:51,760 --> 00:46:55,200
Speaker 1: And so I asked Bianca that the professor, because she

935
00:46:55,280 --> 00:46:57,680
Speaker 1: thinks about this stuff, right, she thinks about what happens

936
00:46:57,760 --> 00:47:01,200
Speaker 1: inside black holes when gravity gets really strong, space gets twisty.

937
00:47:01,680 --> 00:47:04,360
Speaker 1: And I asked her, like, what is your mental image

938
00:47:04,400 --> 00:47:06,600
Speaker 1: of inside a black hole? Because I want to know, right,

939
00:47:06,680 --> 00:47:08,759
Speaker 1: I mean, there's a black hole in her mind at least,

940
00:47:08,800 --> 00:47:10,279
Speaker 1: and I want to know what does it look like

941
00:47:10,520 --> 00:47:11,440
Speaker 1: inside her mind.

942
00:47:11,719 --> 00:47:16,720
Speaker 5: Quantum gravity effects will be only important very near the singularity,

943
00:47:17,160 --> 00:47:20,560
Speaker 5: where the space and curvature is really getting very large.

944
00:47:21,000 --> 00:47:23,319
Speaker 5: And maybe I like to think that there's a new

945
00:47:23,440 --> 00:47:28,440
Speaker 5: universe which opens up with each singularity, which gives us

946
00:47:28,520 --> 00:47:31,080
Speaker 5: much more universes than the normal.

947
00:47:31,640 --> 00:47:34,239
Speaker 1: Yeah, she went there, She went for there are new

948
00:47:34,360 --> 00:47:36,280
Speaker 1: universes inside black holes.

949
00:47:36,320 --> 00:47:39,800
Speaker 3: I love it. There's a new universe in my closet.

950
00:47:39,800 --> 00:47:40,600
Speaker 3: I would believe that.

951
00:47:41,960 --> 00:47:45,200
Speaker 1: And inside that closet there are other closets with other

952
00:47:45,280 --> 00:47:46,440
Speaker 1: closets inside them.

953
00:47:46,760 --> 00:47:50,400
Speaker 3: Meaning that's kind of a consequence of quantum blue gravities

954
00:47:50,440 --> 00:47:53,960
Speaker 3: that when you get to these extreme singularities, These loops

955
00:47:54,040 --> 00:47:56,919
Speaker 3: kind of what like open up or you know, become

956
00:47:56,960 --> 00:47:58,120
Speaker 3: their own little universes.

957
00:47:58,160 --> 00:48:00,640
Speaker 1: Is that the idea I will not pretend to even

958
00:48:00,719 --> 00:48:05,480
Speaker 1: understand what that means, because there's some crazy consequences that

959
00:48:05,680 --> 00:48:09,160
Speaker 1: like if there's a universe inside every black hole, is

960
00:48:09,280 --> 00:48:13,480
Speaker 1: our universe inside a black hole? You know, like maybe

961
00:48:13,520 --> 00:48:16,120
Speaker 1: who knows? It's crazy stuff? Yes, is your answer.

962
00:48:16,280 --> 00:48:18,200
Speaker 3: You're gonna go with the s And that's my third

963
00:48:18,239 --> 00:48:20,400
Speaker 3: Nobel Prize claim.

964
00:48:20,840 --> 00:48:23,759
Speaker 1: Or is that the conclusion to your pitch or your

965
00:48:23,960 --> 00:48:26,320
Speaker 1: loop Quantum gravity sitcom episode?

966
00:48:27,560 --> 00:48:30,120
Speaker 3: There you go at the end of season twenty, it

967
00:48:30,200 --> 00:48:32,280
Speaker 3: turns out they're all in a black hole.

968
00:48:32,640 --> 00:48:34,880
Speaker 1: That's right, and you know, we might be able to

969
00:48:34,880 --> 00:48:37,480
Speaker 1: figure this out in ways other than going to a

970
00:48:37,520 --> 00:48:40,120
Speaker 1: black hole. We actually do have ideas for how you

971
00:48:40,120 --> 00:48:43,080
Speaker 1: could test this, and they revolve around seeing whether we

972
00:48:43,120 --> 00:48:46,080
Speaker 1: can tell the difference in the speed of light from

973
00:48:46,160 --> 00:48:47,839
Speaker 1: high frequency and low frequency light.

974
00:48:48,000 --> 00:48:50,920
Speaker 3: If the speed of light changes, which we didn't think

975
00:48:50,920 --> 00:48:53,239
Speaker 3: it did, but if it changes with frequency, then that's

976
00:48:53,280 --> 00:48:56,080
Speaker 3: an indication maybe there's something loopy going on.

977
00:48:56,440 --> 00:48:59,680
Speaker 1: Yeah, maybe there's something lupy going on, and this would

978
00:48:59,719 --> 00:49:01,640
Speaker 1: be a these small effects. So what you need to

979
00:49:01,680 --> 00:49:04,320
Speaker 1: do is like have a race between photons of different

980
00:49:04,320 --> 00:49:07,799
Speaker 1: frequencies high frequency versus low frequency, and the race would

981
00:49:07,800 --> 00:49:10,960
Speaker 1: have to be super long because light goes super fast,

982
00:49:11,000 --> 00:49:14,000
Speaker 1: of course, and this difference is really small. And so

983
00:49:14,120 --> 00:49:16,319
Speaker 1: what they do is they look for light sources that

984
00:49:16,360 --> 00:49:19,280
Speaker 1: are really really far away and then try to measure

985
00:49:19,400 --> 00:49:21,879
Speaker 1: see if there's a difference in like the arrival time

986
00:49:21,920 --> 00:49:22,640
Speaker 1: of photons.

987
00:49:23,640 --> 00:49:25,400
Speaker 3: I need to know where they're coming from, right.

988
00:49:25,760 --> 00:49:28,120
Speaker 1: Yeah, So we have these sources which are variable, like

989
00:49:28,239 --> 00:49:31,160
Speaker 1: quasars and pulsars that are really far away. You know,

990
00:49:31,200 --> 00:49:33,200
Speaker 1: they pulse, and so you can sort of line the

991
00:49:33,239 --> 00:49:35,279
Speaker 1: two up and say, well, we know these two were

992
00:49:35,280 --> 00:49:37,680
Speaker 1: emitted at the same moment because they're the top of

993
00:49:37,719 --> 00:49:39,920
Speaker 1: the pulse at the same time or something. And then

994
00:49:39,960 --> 00:49:41,920
Speaker 1: you can say, well, do they arrive in sync or

995
00:49:41,920 --> 00:49:43,879
Speaker 1: are they sort of out of sync? And so there's

996
00:49:43,880 --> 00:49:46,680
Speaker 1: a satellite which looked out and measured this and looked

997
00:49:46,680 --> 00:49:46,960
Speaker 1: for this.

998
00:49:47,239 --> 00:49:48,919
Speaker 3: What did they find, Well, this is the.

999
00:49:48,960 --> 00:49:52,239
Speaker 1: Integral satellite and that's some torture acronym for I don't

1000
00:49:52,239 --> 00:49:55,080
Speaker 1: even know what is it really, it's called integral YAP.

1001
00:49:55,640 --> 00:49:58,560
Speaker 1: And what they found they didn't see anything right, They

1002
00:49:58,560 --> 00:50:00,520
Speaker 1: didn't see any difference in the arrival times.

1003
00:50:00,360 --> 00:50:01,200
Speaker 3: Didn't any loops.

1004
00:50:01,320 --> 00:50:03,360
Speaker 1: I didn't see any loops. And they were able to

1005
00:50:03,360 --> 00:50:06,799
Speaker 1: say that if there are loops, they're smaller than ten

1006
00:50:06,880 --> 00:50:09,520
Speaker 1: to the minus forty eight meters.

1007
00:50:10,000 --> 00:50:14,399
Speaker 3: What they can do that, that's one client by looking

1008
00:50:14,480 --> 00:50:15,360
Speaker 3: at two photons.

1009
00:50:15,560 --> 00:50:17,799
Speaker 1: Yeah, by looking at these photons, because the photons come

1010
00:50:17,840 --> 00:50:20,759
Speaker 1: from really really far away, and so these differences would

1011
00:50:20,760 --> 00:50:23,759
Speaker 1: be added up across the universe. And they claim they

1012
00:50:23,760 --> 00:50:24,879
Speaker 1: should have seen them.

1013
00:50:24,960 --> 00:50:26,160
Speaker 3: They saw that they were in sync.

1014
00:50:26,520 --> 00:50:29,960
Speaker 1: They were in sync. Yeah, and this is thirteen orders

1015
00:50:29,960 --> 00:50:32,600
Speaker 1: of magnitudes smaller than what we think the size of

1016
00:50:32,600 --> 00:50:35,440
Speaker 1: the loops are. So like that seems pretty definitive.

1017
00:50:36,160 --> 00:50:38,760
Speaker 3: Yeah, but what did the loop quantum gravity folks say.

1018
00:50:38,920 --> 00:50:41,400
Speaker 1: Well, you know, there's only one branch of loop quantum gravity.

1019
00:50:41,400 --> 00:50:44,680
Speaker 1: The people who say that maybe that's that special relativity

1020
00:50:44,719 --> 00:50:48,120
Speaker 1: needs to be tweaked. Other people have solutions, as you say,

1021
00:50:48,400 --> 00:50:50,880
Speaker 1: to make light travel the same speed no matter what,

1022
00:50:51,239 --> 00:50:53,759
Speaker 1: by having you know, crazy deformations, these things, and all

1023
00:50:53,800 --> 00:50:57,200
Speaker 1: sorts of complicated interactions between light and space, and so

1024
00:50:57,280 --> 00:51:00,160
Speaker 1: it just sort of rules out one branch of of

1025
00:51:00,200 --> 00:51:02,799
Speaker 1: loop quantum gravity. You can never kill these theories. Man,

1026
00:51:02,840 --> 00:51:06,040
Speaker 1: they're like weeds. There's another version that crops up.

1027
00:51:06,040 --> 00:51:09,960
Speaker 3: They're like it's one head of two physicists emerge.

1028
00:51:10,840 --> 00:51:13,160
Speaker 1: But they're fascinating, you know, and each one is a

1029
00:51:13,160 --> 00:51:16,520
Speaker 1: wonderful exploration. Is sort of the intellectual space of like,

1030
00:51:16,600 --> 00:51:20,440
Speaker 1: how could the universe work? What possible universes might we

1031
00:51:20,520 --> 00:51:23,239
Speaker 1: live in? And the amazing thing is that there is

1032
00:51:23,320 --> 00:51:26,280
Speaker 1: an answer, right, there is one way that the universe

1033
00:51:26,600 --> 00:51:27,760
Speaker 1: actually works.

1034
00:51:28,160 --> 00:51:29,960
Speaker 3: And what's kind of interesting, I think is that it

1035
00:51:30,000 --> 00:51:33,439
Speaker 3: wouldn't affect your everyday life, like things would still work

1036
00:51:33,480 --> 00:51:35,600
Speaker 3: the same way. But who knows what's going on down

1037
00:51:35,640 --> 00:51:37,880
Speaker 3: at the fundamental level, right, it could be one of

1038
00:51:37,920 --> 00:51:40,880
Speaker 3: these crazy theoretical ideas.

1039
00:51:40,960 --> 00:51:43,640
Speaker 1: Yeah, and it's important now to scientists, but it might

1040
00:51:43,680 --> 00:51:47,160
Speaker 1: eventually be important to engineers. You know. Knowledge that seems

1041
00:51:47,160 --> 00:51:51,360
Speaker 1: impractical and useless but reveals the fundamental nature of reality

1042
00:51:51,440 --> 00:51:55,040
Speaker 1: could eventually be useful. And hey, to me, that's fun anyway.

1043
00:51:55,080 --> 00:51:56,320
Speaker 1: I don't really care if it's useful.

1044
00:51:56,360 --> 00:51:58,839
Speaker 3: I just gotta know, right, Yeah, I mean I think

1045
00:51:58,880 --> 00:52:02,680
Speaker 3: that's how microways were bent. It actually by accident, by

1046
00:52:02,760 --> 00:52:05,439
Speaker 3: looking at something else. And where would we be? Where

1047
00:52:05,440 --> 00:52:06,759
Speaker 3: would burtas be these days.

1048
00:52:06,840 --> 00:52:07,239
Speaker 6: That's right.

1049
00:52:07,280 --> 00:52:10,120
Speaker 1: And you know, there have been actually fascinating advances in

1050
00:52:10,280 --> 00:52:14,120
Speaker 1: microwave and the technology the engineering of microwaves.

1051
00:52:13,600 --> 00:52:15,520
Speaker 3: And I guess you know, if you can unlock kind

1052
00:52:15,520 --> 00:52:17,719
Speaker 3: of the magic and the power that's happening at that

1053
00:52:17,840 --> 00:52:21,319
Speaker 3: microscopic level, who knows what you could do, right, what

1054
00:52:21,440 --> 00:52:24,160
Speaker 3: kind of energies you can get, or what kinds of

1055
00:52:24,719 --> 00:52:30,120
Speaker 3: warped drives or microwave ovens. Yeah, microwave toaster ovens powered

1056
00:52:30,120 --> 00:52:31,600
Speaker 3: by artificial intelligence.

1057
00:52:32,640 --> 00:52:34,120
Speaker 1: Yeah. And so I have to give a shout out

1058
00:52:34,160 --> 00:52:36,760
Speaker 1: to Nico. He's one of our listeners and he heard

1059
00:52:36,960 --> 00:52:40,360
Speaker 1: our episode about microwave ovens actually, and he wrote to

1060
00:52:40,400 --> 00:52:42,560
Speaker 1: me and told me that they have a new fancier

1061
00:52:42,800 --> 00:52:47,400
Speaker 1: AI powered microwave oven which can heat stuff up at

1062
00:52:47,400 --> 00:52:50,000
Speaker 1: different temperatures and monitor it to make sure the heating

1063
00:52:50,080 --> 00:52:52,520
Speaker 1: is all smooth and fancy. And actually drop by my

1064
00:52:52,600 --> 00:52:55,480
Speaker 1: house and delivered one of these prototypes, which has been

1065
00:52:55,640 --> 00:52:56,400
Speaker 1: a lot of fun.

1066
00:52:56,880 --> 00:52:59,400
Speaker 3: That's amazing that you let one of you our listeners

1067
00:52:59,400 --> 00:52:59,959
Speaker 3: into your house.

1068
00:53:00,560 --> 00:53:02,799
Speaker 1: Hey, he was offering a brand new appliance, so I thought.

1069
00:53:03,160 --> 00:53:04,640
Speaker 1: And while he was there, I asked him about Luke

1070
00:53:04,719 --> 00:53:06,560
Speaker 1: quantum gravity, but he didn't have any ideas.

1071
00:53:06,640 --> 00:53:10,080
Speaker 3: Oh man, there's no setting on that in the microwave.

1072
00:53:10,040 --> 00:53:13,160
Speaker 1: Not yet. The next version of the prototype will be

1073
00:53:13,239 --> 00:53:14,760
Speaker 1: quantum gravity powered, I'm sure.

1074
00:53:14,920 --> 00:53:18,200
Speaker 3: All right, Well, it sounds like the answer is stay tuned.

1075
00:53:18,440 --> 00:53:21,040
Speaker 3: You know, that's what we explain, what Luke. Quantum gravity

1076
00:53:21,160 --> 00:53:23,279
Speaker 3: is and who knows, and maybe it is the way

1077
00:53:23,320 --> 00:53:26,040
Speaker 3: that the universe works at that level, and we may

1078
00:53:26,080 --> 00:53:27,920
Speaker 3: find out in the near future.

1079
00:53:28,120 --> 00:53:31,200
Speaker 1: That's right, And these are the kinds of mysteries that

1080
00:53:31,320 --> 00:53:33,279
Speaker 1: are going to help us figure out the deep nature

1081
00:53:33,280 --> 00:53:35,400
Speaker 1: of the universe. You know. It's when things break that

1082
00:53:35,480 --> 00:53:38,480
Speaker 1: we have an opportunity to figure out how things should work.

1083
00:53:38,800 --> 00:53:41,120
Speaker 1: And so it's exciting to have these kind of problems.

1084
00:53:41,120 --> 00:53:43,640
Speaker 1: It's exciting to know sort of where to work, even

1085
00:53:43,680 --> 00:53:45,400
Speaker 1: if we don't know what the answer should look like.

1086
00:53:45,760 --> 00:53:47,840
Speaker 3: All right, well, we hope you enjoyed that, Daniel. How

1087
00:53:47,920 --> 00:53:50,160
Speaker 3: much did this podcast cost me in terms of your

1088
00:53:50,160 --> 00:53:50,799
Speaker 3: physics time?

1089
00:53:51,000 --> 00:53:56,520
Speaker 1: One loop one? That's ten to the minus thirty five dollars.

1090
00:53:57,040 --> 00:53:58,800
Speaker 3: Ten to the minus thirty five dollars.

1091
00:53:58,840 --> 00:53:59,719
Speaker 1: One plank dollar.

1092
00:53:59,800 --> 00:54:02,879
Speaker 3: Yeah, a pika a plank dollar. Oh good, I got

1093
00:54:02,920 --> 00:54:04,160
Speaker 3: a couple here in my pocket.

1094
00:54:04,440 --> 00:54:06,879
Speaker 1: Okay, quantum them over to me all right.

1095
00:54:07,160 --> 00:54:09,600
Speaker 3: We hope you enjoyed that. Thanks for joining us.

1096
00:54:09,440 --> 00:54:11,440
Speaker 1: And as usual, thank you to everybody who wrote in

1097
00:54:11,480 --> 00:54:12,200
Speaker 1: with your questions.

1098
00:54:12,440 --> 00:54:13,319
Speaker 3: See you next time.

1099
00:54:21,000 --> 00:54:23,359
Speaker 1: Before you still have a question after listening to all

1100
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Speaker 1: these explanations, please drop us a line. We'd love to

1101
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Speaker 1: hear from you. You can find us at Facebook, Twitter,

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Speaker 1: and Instagram at Daniel and Jorge That's one word, or

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Speaker 1: email us at Feedback at Danielandhorge dot com. Thanks for

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Speaker 1: listening and remember that Daniel and Jorge Explain the Universe

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Speaker 1: is a production of iHeartRadio. For more podcasts from iHeartRadio,

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