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Speaker 6: Hey Daniel, how smart do you have to be to

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Speaker 6: be a physicist?

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Speaker 1: You know, it's not actually about being smart. It's more

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Speaker 1: about thinking that these kind of particular challenges are really fun.

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Speaker 6: So if you like having fun, you shouldn't be a physicist. Wait,

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Speaker 6: what do you mean?

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Speaker 1: I mean, you know, science is a very personal thing.

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Speaker 1: So some people might think doing integrals is really boring,

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Speaker 1: and somebody else might do them to relax.

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Speaker 6: Well, are you saying math can be relaxing. It can

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Speaker 6: be relaxing, and it can also be exciting. You know,

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Speaker 6: sometimes you're like bush whacking through the math and you

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Speaker 6: make amazing discoveries and you don't even have to risk

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Speaker 6: your life to jaguars. Well you do have to worry

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Speaker 6: about paper cuts, right.

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Speaker 1: Yeah, you know, I think there's a reason they didn't

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Speaker 1: make Indiana Jones a physicist.

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Speaker 6: Yeah, I don't think physicists could pull off the Indiana

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Speaker 6: Jones hat.

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Speaker 1: And we all have daddy issues.

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Speaker 6: Hi. I'm Jorge make, cartoonist and the author of Oliver's

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Speaker 6: Great Big Universe.

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

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Speaker 1: at UC Irvine, and I always wanted to have physics adventures.

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Speaker 6: Ooh, like real adventures, like in your couch, like oh no,

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Speaker 6: I spilled my coffee.

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Speaker 1: I don't think you have to risk your life and

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Speaker 1: like get into a spaceship or even become an astronaut

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Speaker 1: to have physics adventures. You know, you can explore the

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Speaker 1: universe in your mind, make amazing discoveries, and feel like

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Speaker 1: you are connecting yourself to the universe.

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Speaker 6: M I guess technically aren't like real adventures physical adventures.

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Speaker 6: But I guess maybe you don't want physical adventures. You

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Speaker 6: want physics adventures.

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Speaker 1: Yeah, exactly, physics versus physical.

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Speaker 6: You don't want to make any physical exertions or efforts,

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Speaker 6: just like the mental kind.

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Speaker 1: Yeah, but you know, sometimes thinking really hard can make sweat.

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Speaker 1: I've definitely perspired while doing intergals before m.

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Speaker 6: I see, have you ever wiped out doing integrals?

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Speaker 1: I've never injured myself doing math, that's for sure.

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Speaker 6: Well, I guess some people headaches. I guess that's sort

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Speaker 6: of cow injury exactly. Migraines are a hazard of doing

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Speaker 6: physic Yeah, no, I find math very relaxing. Actually puts

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Speaker 6: me right to sleep. In fact, you should make an

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Speaker 6: app for that, like a sleep relaxation app. And now

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Speaker 6: we're going to do integrals.

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Speaker 1: People do like the call sign. There you go, that's

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Speaker 1: very ASMR.

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Speaker 6: Yeah, and you will be subliminally learning many.

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Speaker 1: A billion dollar idea right here.

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Speaker 6: Yeah, I can finally quit this podcast job. But anyways,

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Speaker 6: welcome to our podcast Daniel and Jorge Explain the Universe,

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Speaker 6: a production of iHeartRadio.

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Speaker 1: In which we do our best to make the complexities

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Speaker 1: and the challenges of physics accessible to you and to everybody,

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Speaker 1: because we think that the whole point of physics is

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Speaker 1: to understand the universe, and not just by a select

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Speaker 1: few group of people who can understand nineteen dimensional string

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Speaker 1: theory integrals, but by everybody. Because in the end, science

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Speaker 1: is a bunch of stories, mathematical or intuitive or in English,

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Speaker 1: and we want to tell those stories to you.

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Speaker 6: It's right. We take you through the adventures of science,

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Speaker 6: the wipeouts, the close calls, and the headaches of trying

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Speaker 6: to find out how the universe works and what are

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Speaker 6: placed in it is.

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Speaker 1: Sometimes these integrals are more annoying than mosquito bites, though

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Speaker 1: never as dangerous as jaguars.

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Speaker 6: I don't think anything is this annoying as mosquito bites.

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Speaker 6: Jaguars are pretty pesky too. Have you ever seen a

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Speaker 6: jaguar in the wild in the wild? Uh no, no,

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Speaker 6: thankfully not. Or do you mean like a car the car?

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Speaker 6: I think plenty of jaguars around here in South Pasady.

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Speaker 1: That's true, and those drivers can be pretty dangerous.

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Speaker 6: Yeah, yeah, and annoying like moisquitoes.

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Speaker 1: You just want to swat all the jaguar drivers.

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Speaker 6: No, no, that's a You can get arrested for that

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Speaker 6: kind of thing. Yeah, exactly, Well, let me insult them

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Speaker 6: on a podcast.

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Speaker 1: When you make a billion on your sleep math app

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Speaker 1: then you can buy yourself a jaguar and you can

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Speaker 1: be the same one.

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Speaker 6: I can buy several jaguars and a mosquito repellent.

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Speaker 1: Well, I was just wondering, because I know you grew

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Speaker 1: up in Panama, if you'd ever seen a jaguar or

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Speaker 1: maybe just jaguar sized mosquitoes.

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Speaker 6: Oh I see, I see that's your your perception of

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Speaker 6: how I grew up. I grew up in the hut,

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Speaker 6: in the jungle, barefoot, with my little pet jaguar next

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Speaker 6: to me. Is that? How do you think people in

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Speaker 6: tana will live?

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Speaker 1: No, I'm asking paint us the picture.

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Speaker 6: I've seen a lot of coyotes around here in the while. Yes, yeah,

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Speaker 6: those are pretty dangerous too. I guess if you're the

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Speaker 6: if you're a small you're a small baby or something.

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Speaker 1: In our neighborhood, everybody with a small dog puts these

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Speaker 1: spiky vests on them so the coyotes can't just snatch

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Speaker 1: them up and have a snack.

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Speaker 6: Wait, what you turn your dog into a weapon? What

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Speaker 6: do you mean is like spy? How dangerous are these spikes?

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Speaker 1: They're pretty big because the whole epidemic of coyotes jumping

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Speaker 1: into people's backyards and like grabbing these little dogs.

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Speaker 6: Oh wow, maybe just not keep your dog out at night.

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Speaker 6: Don't turn it into dangerous weapon. Like what if the

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Speaker 6: dog runs at a little kid or something wearing this

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Speaker 6: killer jacket.

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Speaker 1: Yeah, these coyotes are pretty brazen. It's not just that night,

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Speaker 1: during the full daylight, they will hop in people's backyards

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Speaker 1: and make off with their little Shitsues.

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Speaker 6: Sounds like maybe you just just make the coyotes your pets,

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Speaker 6: and then that's also the problem, doesn't it. Well, Lass,

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Speaker 6: then you get a problem of jaguars coming in here

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Speaker 6: and eating your coyotes.

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Speaker 1: And somehow we have to connect all of this back

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Speaker 1: to physics.

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Speaker 6: Yeah, no, there's a physics zero of sizes right right,

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Speaker 6: yah sizes.

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Speaker 1: Yes, some problems are hard, like how to protect your

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Speaker 1: little pet from neighborhood coyotes, and other problems are hard,

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Speaker 1: like how do you figure out the mathematics of the universe?

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Speaker 6: It's all connected, yeah, because I guess figuring out the

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Speaker 6: math of the universe has been one of the goals

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Speaker 6: of physics, to understand what's underlying everything that we see

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Speaker 6: around this and all of the mechanics and the emotion

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Speaker 6: and the energy that is swirling around us, what is

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Speaker 6: at the core of the universe.

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Speaker 1: Physics has two great theories, two incredible ideas that have

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Speaker 1: been very very successful, quantum mechanics and general relativity. But

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Speaker 1: bringing them together into an idea of quantum gravity. Has

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Speaker 1: been a challenge that has stood for over a century.

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Speaker 1: The greatest minds in physics have tried to take a

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Speaker 1: bite out of it, but it seems to be protected

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Speaker 1: by a spiky vest.

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Speaker 6: That's right. It's been one of the hardest problems to

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Speaker 6: solve in physics for the last one hundred years, which

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Speaker 6: makes you wonder why is it so hard? What's taking

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Speaker 6: so long to solve this fundamental problem in physics.

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Speaker 1: It's because us physicists haven't just gotten off our couch

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Speaker 1: and bush whacked our way into the mathematical jungle.

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Speaker 6: Yeah. Yeah, I think that's the problem, Daniel. You need

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Speaker 6: to get off your couch an experiment with real gravity,

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Speaker 6: not just like imagine ner gravity.

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Speaker 1: I'm waiting for my Indiana Jones had to come. You

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Speaker 1: can't do it without the right cand of hat. You

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Speaker 1: have to be prepared.

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Speaker 6: Oh that's right, Yeah, that's right. You don't want to

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Speaker 6: get sunburned. It's not like there are other ways to

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Speaker 6: protect yourselves from the UV rays.

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Speaker 1: I mean, I want to understand the universe, but I'm

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Speaker 1: not willing to make physical sacrifices.

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Speaker 6: Do you also need a whip. Also, I want to

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Speaker 6: whip those integrals into shape for sure. Yeah, there you go,

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Speaker 6: crack them into shape. But anyway, to be on the podcast,

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Speaker 6: we'll be tackling the question why is quantum gravity so hard? Now?

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Speaker 6: Is this like hard like difficult or hard like tough?

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Speaker 1: If your floors are made of quantum gravity and you

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Speaker 1: drop your glass, man, is it going to shatter? Yeah?

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Speaker 6: But how is it going to fall without gravity?

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Speaker 1: Quantum mechanics?

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Speaker 6: I answered everything, it's going to fall and not fall. No.

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Speaker 1: I love that physics has a name for this, the

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Speaker 1: quantum gravity, but it's just kind of like a placeholder.

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Speaker 1: We don't know what it is, or how it works

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Speaker 1: or what the mathematics of it are. People argue about

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Speaker 1: different approaches. We already have a name for it, but

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Speaker 1: we haven't even figured it out yet.

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Speaker 6: Sounds on brand for how physicist name thinks. Well, anyways,

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Speaker 6: we're wondering, as usual, how many people out there had

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Speaker 6: thought about this question of why quantum gravity is so hard?

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Speaker 6: As usual, Daniel went out there and God answers from

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Speaker 6: real people.

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Speaker 1: Thank you to all the real people and definitely not

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Speaker 1: made up chat GPT inspired bots who answered this question

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Speaker 1: if you are a real person and you'd like to

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Speaker 1: answer future questions, Please write me two questions at Danielandjorge

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Speaker 1: dot com.

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Speaker 6: So think about it for a second. Why do you

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Speaker 6: think quantum gravity is so hard to solve? Here's what

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Speaker 6: people have to say.

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Speaker 4: I know that.

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Speaker 7: Quantum mechanic is very good explaining things that happen in

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Speaker 7: very small scale, and gravity is not very in a

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Speaker 7: small as scale.

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Speaker 1: I don't know.

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Speaker 6: I think that's the reason, but I don't really I

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Speaker 6: don't really know. I honestly don't have an intelligent answer

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Speaker 6: for that.

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Speaker 8: But I will say this, if Albert Einstein was afraid

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Speaker 8: of it, that I am too.

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Speaker 7: It's hard because we are trying to apply our comparatively

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Speaker 7: super massive vantage point to these tiny particles in the

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Speaker 7: quantum realm that probably don't even know the difference. They

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Speaker 7: probably don't even know that gravity is a force.

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Speaker 1: Did you mean real people as opposed to chat GPT

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Speaker 1: or real people as opposed to physicists. I'm just now

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Speaker 1: realizing that was a jab.

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Speaker 6: I mean, like not paid actors, although maybe you should

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Speaker 6: include a chat GPT answer every every time we do this. Yeah,

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Speaker 6: that's right. Now, what'st say about quantum gravity being so hard.

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Speaker 1: Chat ChiPT says quantum gravity is consider challenging because it

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Speaker 1: involves the attempt to reconcile two fundamental theories of physics,

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Speaker 1: quantum mechanics and general relativity. Each of these has been

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Speaker 1: incredibly successful on its own, but becomes problematic when combined.

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Speaker 6: WHOA, it just did the podcast for us? Done? AI

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Speaker 6: did replace in our job? Does a chat GBT have

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Speaker 6: like a like a voice output? Can you have it

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Speaker 6: read the answer?

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Speaker 1: I think the free version that I have access to

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Speaker 1: can't do images or voices, So no, you cannot be

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Speaker 1: replaced by chat gipt just yet.

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Speaker 6: Oh right, you still need us to read the answer

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Speaker 6: chat GPT gives out. I see.

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Speaker 1: Also, I would never rely on chatcheapt. I asked some

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Speaker 1: hard physics questions sometimes and it just makes up bologny. Oh.

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Speaker 6: I think the news here is that you're asking chat

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Speaker 6: GPT for answers.

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Speaker 1: Yeah. I like everybody else, I was curious when it

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Speaker 1: came out, what you like to talk to the average

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Speaker 1: of the internet wisdom and follies, And the answer is

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Speaker 1: it's not very reliable.

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Speaker 6: Well, technically, neither are we, Daniel. I don't think we're

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Speaker 6: gonna have a hard answer here today.

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Speaker 1: No, but we're not going to make stuff up.

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Speaker 6: Well, so let's dig into this question. Why is quantum

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Speaker 6: gravity so hard? Why is it so difficult? Why has

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Speaker 6: it puzzled physicists for over one hundred years? So let's

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Speaker 6: start with the basics, Daniel, what is quantum gravity?

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Speaker 1: So Chatchimititi got this bit right. Quantum gravity is an

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Speaker 1: attempt to bring together are two great theories of physics,

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Speaker 1: quantum mechanics that describes things like electromagnetism and how particles

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Speaker 1: work and gives us a probabilistic picture of the universe,

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Speaker 1: and general relativity that describes space and time and gravity

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Speaker 1: and explains things like the expansion of the universe and

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Speaker 1: how things move through space and time. And both of

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Speaker 1: these work really really well in their own regime. Quantum

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Speaker 1: mechanics for the small stuff, job relativity for were the

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Speaker 1: big stuff, quantum gravities, and attempt to have a single

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Speaker 1: consistent theory that works for all the stuff.

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Speaker 6: And these were developed independently, sort of, right like, while

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Speaker 6: Einstein was coming up with general relativity, other people were

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Speaker 6: thinking about things at the smallest level and why they

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Speaker 6: were quantized.

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Speaker 1: Right exactly. They were developed independently though around the same time,

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Speaker 1: and both were actually sparked by Einstein. Quantum mechanics really

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Speaker 1: got its kickoff from Einstein's realization that the photo electric effect,

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Speaker 1: what happens when you shine a bright light at a

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Speaker 1: piece of metal, could only be explained by the fact

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Speaker 1: that photons were little packets. They were quantized. They weren't

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Speaker 1: just continuous beams of energy, because what you saw was

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Speaker 1: as you turned up the energy of that beam of light,

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Speaker 1: you didn't get electrons with more energy boiling off. You

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Speaker 1: got more electrons because each one just gets one serving

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Speaker 1: one photon. That was explained by saying the beam of

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Speaker 1: light had more photons in it, not just a brighter beam.

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Speaker 1: So Einstein and kicked off quantum mechanics around the turn

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Speaker 1: of the century, and at the same time he developed

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Speaker 1: his theory of special relativity and general relativity that explained

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Speaker 1: the apparent force of gravity. And these two have been

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Speaker 1: in parallel development over the last hundred years, but nobody's

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Speaker 1: been able to bring them together into one picture of

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Speaker 1: how the universe works.

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Speaker 6: I guess maybe the question is why do you want

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Speaker 6: to bring them together? Like if you have one that

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Speaker 6: works really well for some things, and the other one

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Speaker 6: works well for other things. What's the need to unify them?

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Speaker 1: Yeah, it's a fair question.

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Speaker 2: You know.

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Speaker 1: Sometimes in life we have things that are separate. Like

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Speaker 1: you got one group of friends and another group of friends,

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Speaker 1: you bring them together, it's awkward. You don't do it again, right.

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Speaker 6: Yeah, they're usually a bad idea.

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Speaker 1: And I guess in this case there are two answers.

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Speaker 1: One is philosophical and the other really is experimental. Philosophically,

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Speaker 1: we just think that the universe probably does have a

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Speaker 1: single set of laws. You know, there should be one

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Speaker 1: explanation for why something happens. You know, the same way

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Speaker 1: like when a computer program runs running with one source code.

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Speaker 1: It's not like there's two codes there battling it out.

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Speaker 1: There should be one explanation. And this is just sort

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Speaker 1: of like a philosophical preference. It would be nice if

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Speaker 1: the universe had a single, unified theory. It would sort

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Speaker 1: of make sense to our brains. That doesn't mean it

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Speaker 1: has to happen. It's just sort of like a philosophical preference.

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Speaker 6: Well, maybe explain to folks how they're separate. So, for example,

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Speaker 6: quantum mechanics work to describe what exactly like the motions

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Speaker 6: or of little tiny particles or their interactions, or what

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Speaker 6: exactly does quantum mechanics do.

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Speaker 1: Quantum mechanics describes everything about tiny little particles, their motion,

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Speaker 1: their interactions, what's going to happen, what's not going to happen.

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Speaker 1: If you have, for example, two electrons and they're interacting

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Speaker 1: with each other, quantum mechanics tells you what's going to happen.

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Speaker 1: You make two electron beams, you should them at each other.

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Speaker 1: Quantum mechanics tells you the probabilities of what will come

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Speaker 1: out of those collisions. Or if you replace an electron

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Speaker 1: with a muon, you put in a quark or a

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Speaker 1: proton or whatever. Quantum mechanics is the rules of all

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Speaker 1: of those interactions. And the standard model of particle physics.

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Speaker 1: What we talk about on this podcast all the time

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Speaker 1: that has been super successful in explaining the structure of

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Speaker 1: matter deep down inside the atom, and why everything's bound

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Speaker 1: together and how that all works, that's all quantum mechanics.

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Speaker 1: It's all fundamentally quantum mechanics. Every little bit of it

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Speaker 1: is quantum mechanical, and it's quantum mechanical because it paints

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Speaker 1: this picture of how the universe works that's very different

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Speaker 1: from the way that our universe seems to work, the

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Speaker 1: one on our level, you know about baseballs and planets

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Speaker 1: and basketballs, where things have like smooth paths. It tells

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Speaker 1: us that fundamentally the universe follows very different rules. That

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Speaker 1: quantum objects, tiny little bits, only have probabilities to go

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Speaker 1: places they don't have smooth.

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Speaker 6: Paths, right, thinks are kind of fuzzy down at the

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Speaker 6: microscopic level. What does general relativity do exactly?

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Speaker 1: So? General relativity explains space and time and gravity, So

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Speaker 1: it says that Newton described as a force of gravity

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Speaker 1: is actually just objects moving through curved space. Newton imagined

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Speaker 1: space was absolute as this backdrop of the universe, and

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Speaker 1: then things with mass had a force between them. You know.

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Speaker 1: He's famously explained that apple dropping and also the Moon

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Speaker 1: orbiting the Earth unified in his law of gravity as

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Speaker 1: an attraction between mass. But Einstein tells us that that's

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Speaker 1: not the case. General relativity tells us that actually things

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Speaker 1: are just moving through the curvature of space. Space itself

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Speaker 1: is curved when mass is nearby, and that changes the

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Speaker 1: natural inertial path of objects. Objects will move in what

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Speaker 1: looks like curves even without accelerating.

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Speaker 6: And space gets spent by gravity, right, or gravity is

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Speaker 6: the bending of space, right.

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Speaker 1: Bace gets spent by energy in a very complex way. Essentially,

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Speaker 1: mass isn't a kind of energy, so it helps bend space,

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Speaker 1: but it's not the only way you can bend space.

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Speaker 1: And gravity is sort of a fuzzy term. Now, it's like,

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Speaker 1: are you referring to the Newtonian force, which isn't really

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Speaker 1: part of our picture anymore, or you're talking about the

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Speaker 1: whole theory of general relativity as an explanation for it.

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Speaker 1: But you know, what we describe as gravity things seeming

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Speaker 1: to fall down is explained by Einstein, is things just

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Speaker 1: following the curvature of.

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Speaker 6: Space, which gets a curve because of the presence of energy. Right,

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Speaker 6: that's the basic and that effect basically you can sider

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Speaker 6: lump it into the idea of gravity.

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Speaker 1: Yeah, exactly. And we had a whole podcast digging deep

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Speaker 1: into like why gravity isn't the force and how if

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Speaker 1: you're moving along with the curvature of space time you

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Speaker 1: don't feel any acceleration even if other people see you,

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Speaker 1: like moving in circles or moving towards the center of

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Speaker 1: the Earth, all that kind of stuff. It's a really

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Speaker 1: fascinating different way to think about how the universe works.

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Speaker 1: It tells a very different story from Newton's, but it

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Speaker 1: mostly describes really really big stuff because you need a

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Speaker 1: lot of mass to curve space, and that curvature is

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Speaker 1: kind of gentle. So the effect of that curvature is

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Speaker 1: hard to measure, especially compared to these quantum forces, which

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Speaker 1: are extraordinarily powerful in compar prison.

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Speaker 6: All right, so now maybe paint us a picture of

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Speaker 6: how they are not unified, Like can I just have

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Speaker 6: some quantum particles interacting in a gravitational field? Or can

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Speaker 6: I just have the path of a quantum particle bent

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Speaker 6: by the bending of space and time? What doesn't these

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Speaker 6: two things do together? Like what are scenarios in which

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Speaker 6: they exclude each other?

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Speaker 1: Yeah? Great, And so this is sort of like number

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Speaker 1: two reason why we want to unify them because in

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Speaker 1: some situations they disagree. Like we talked earlier about having

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Speaker 1: separate theories of the universe, maybe that's cool, but it's

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Speaker 1: not cool if they're talking about the same phenomenon. If

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Speaker 1: you're asking them the question what happens here? Most of

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Speaker 1: the time you can keep them separate because for tiny

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Speaker 1: little particles you can ignore gravity. Gravity is very very

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Speaker 1: weak for the little particles, and for really big stuff,

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Speaker 1: quantum effects mostly average out. You don't need to know

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Speaker 1: quantum mechanics to predict the path of a baseball. But

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Speaker 1: in some scenarios they do disagree, things like what happens

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Speaker 1: inside a black hole. That's a scenario where you have

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Speaker 1: really powerful gravity, so gravity can no longer be ignored,

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Speaker 1: and things are very very small because we think that

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Speaker 1: things are super compressed inside a black hole, so quantum

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Speaker 1: effects are important. So super duper massive, very very tiny objects,

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Speaker 1: quantum mechanics and general relativity disagree about what happens there,

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Speaker 1: and so the universe can't have a contradiction. Two theories

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Speaker 1: tell different stories. They can't both be right.

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Speaker 6: But I guess I mean, in like an everyday scenario,

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Speaker 6: do they work together? Sort of Like if I'm imagining,

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Speaker 6: say a microscopic particle like an electron out there in

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Speaker 6: a near Earth orbit, and it's floating out there in

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Speaker 6: space close to the Earth, does it get pulled by gravity?

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Speaker 6: Is it going to fall down to Earth? Is there

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Speaker 6: a problem with me trying to use quantum mechanics to

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Speaker 6: model how it falls to Earth.

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Speaker 1: Yeah, so you might think, can't we just test quantum

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Speaker 1: gravity and figure out like what the answer is, which

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Speaker 1: one's right by looking at the gravity of a tiny

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Speaker 1: quantum particle, Right, So that's what you're asking. What happens

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Speaker 1: for the Earth's gravity on an electron?

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Speaker 6: Yeah, two theories breakdown or do they agree on their

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Speaker 6: normal conditions that are not inside of a black hole?

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Speaker 1: So the two do not agree about what happens to

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Speaker 1: an electron in the Earth's gravitational field.

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Speaker 6: They don't.

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Speaker 1: They don't, but they're not both relevant at the same time.

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Speaker 1: It's a little tricky, and the issue is how do

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Speaker 1: you calculate the gravitational field of the electron, or even

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Speaker 1: the gravitational force on the electron, or the effective curve

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Speaker 1: space however you want to say it, because that depends

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Speaker 1: on where the electron is. If the electron is a

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Speaker 1: little quantum particle with quantum effects, then maybe it has

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Speaker 1: like a fifty percent chance to be at this altitude

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Speaker 1: and fifty percent chance to be at that altitude, in

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Speaker 1: which case it would feel different amounts of gravity. And

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Speaker 1: so how do you calculate the gravity on a quantum particle,

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Speaker 1: we don't know. The theory of quantum gravity would tell

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Speaker 1: us how to do that, but general relativity doesn't tell

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Speaker 1: us how to do that. General relativity requires that you

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Speaker 1: know where the electron is, and so it ignores its

442
00:22:56,720 --> 00:22:59,400
Speaker 1: quantum nature. So if the quantum nature of the electron

443
00:22:59,480 --> 00:23:02,479
Speaker 1: is important to doing quantumy stuff, then we don't know

444
00:23:02,520 --> 00:23:05,399
Speaker 1: how to calculate the force of gravity on it. But also,

445
00:23:05,800 --> 00:23:08,560
Speaker 1: we can't measure the force of gravity on a tiny

446
00:23:08,600 --> 00:23:11,440
Speaker 1: little object because the force is so small, because its

447
00:23:11,480 --> 00:23:12,439
Speaker 1: mass is so small.

448
00:23:13,400 --> 00:23:16,840
Speaker 6: Sounds like a great situation and maybe one that we

449
00:23:16,920 --> 00:23:18,960
Speaker 6: need a little bit more time on. So let's dig

450
00:23:19,000 --> 00:23:23,080
Speaker 6: into that scenario and dig into how exactly these two

451
00:23:23,119 --> 00:23:25,720
Speaker 6: theories don't match up, and then we'll get into a

452
00:23:25,800 --> 00:23:27,920
Speaker 6: little bit of the math that makes it so hard

453
00:23:27,920 --> 00:23:29,960
Speaker 6: to integrate the two. So let's do that, But first

454
00:23:30,000 --> 00:23:45,280
Speaker 6: let's take a quick break. All right, we're talking about

455
00:23:45,440 --> 00:23:50,119
Speaker 6: why quantum gravity theory that unites quantum mechanics and general

456
00:23:50,160 --> 00:23:53,359
Speaker 6: relativity it's so hard to come up with and to

457
00:23:53,400 --> 00:23:57,440
Speaker 6: make these two theories play well together. Daniel, We're talking

458
00:23:57,440 --> 00:24:01,400
Speaker 6: about a scenario in which I haven't electron in near

459
00:24:01,800 --> 00:24:04,760
Speaker 6: Earth orbit. It's out there in space above the atmosphere,

460
00:24:04,760 --> 00:24:06,800
Speaker 6: and I'm trying to figure out what's going to happen

461
00:24:06,840 --> 00:24:08,800
Speaker 6: to this electron. Is it going to fall to Earth?

462
00:24:09,640 --> 00:24:11,400
Speaker 6: What path is it going to take as it falls

463
00:24:11,440 --> 00:24:15,080
Speaker 6: to Earth? And you're saying that it's hard to theoretically

464
00:24:15,160 --> 00:24:17,560
Speaker 6: predict what's going to happen, right, because it's definitely going

465
00:24:17,600 --> 00:24:22,040
Speaker 6: to fall. If I put an electron on your Earth, right, Like,

466
00:24:22,080 --> 00:24:24,159
Speaker 6: it's going to do something, But we don't really have

467
00:24:24,200 --> 00:24:25,919
Speaker 6: a good theory to predict what it's going to do.

468
00:24:25,960 --> 00:24:28,080
Speaker 1: Is that what you're saying, we can't be very very

469
00:24:28,119 --> 00:24:31,440
Speaker 1: precise about its predictions. We can be approximate. Like there's

470
00:24:31,440 --> 00:24:33,760
Speaker 1: two approaches you can take. You can say, I'm going

471
00:24:33,800 --> 00:24:35,720
Speaker 1: to ignore the quantum mechanical part of it. I'm just

472
00:24:35,720 --> 00:24:38,240
Speaker 1: going to treat the electron like it's a tiny little

473
00:24:38,320 --> 00:24:41,080
Speaker 1: rock or a tiny little ball. I'm going to calculate

474
00:24:41,119 --> 00:24:43,800
Speaker 1: its gravity and I think about how it's basically in

475
00:24:44,000 --> 00:24:46,399
Speaker 1: orbit around the Earth. And you can do that and

476
00:24:46,440 --> 00:24:49,440
Speaker 1: you get very good predictions, and you can calculate how

477
00:24:49,480 --> 00:24:51,719
Speaker 1: things boil off the top of the atmosphere or they

478
00:24:51,760 --> 00:24:54,600
Speaker 1: fall to Earth or whether they're in stable orbits or not.

479
00:24:54,680 --> 00:24:58,000
Speaker 1: So basically ignore the quantum nature of the electron, treat

480
00:24:58,000 --> 00:25:01,280
Speaker 1: it like a tiny classical object, and do gravity on it.

481
00:25:01,520 --> 00:25:03,840
Speaker 6: That's one approach, But then you're saying it's hard to

482
00:25:04,000 --> 00:25:07,800
Speaker 6: know how much gravity is applied to the electron because

483
00:25:07,840 --> 00:25:11,400
Speaker 6: of quantum mechanics, or is it hard? Can you just say, like,

484
00:25:11,520 --> 00:25:13,880
Speaker 6: the electron has this much mass and it's a little

485
00:25:13,880 --> 00:25:16,000
Speaker 6: tiny rock, and so that's how much gravity's going to

486
00:25:16,000 --> 00:25:18,399
Speaker 6: feel or is that at some level wrong?

487
00:25:18,600 --> 00:25:21,200
Speaker 1: Well, that's at some level wrong because you're ignoring the

488
00:25:21,280 --> 00:25:23,280
Speaker 1: quantum nature of the electrons. You're treating it like a

489
00:25:23,320 --> 00:25:25,080
Speaker 1: tiny rock and it's not a tiny rock.

490
00:25:25,160 --> 00:25:26,720
Speaker 6: Yeah, but I guess I mean, like, if you do

491
00:25:26,800 --> 00:25:29,800
Speaker 6: treat it like a rock, do you get something wildly

492
00:25:29,880 --> 00:25:32,400
Speaker 6: off or do you get something that seems to be

493
00:25:32,440 --> 00:25:33,199
Speaker 6: pretty exact?

494
00:25:33,520 --> 00:25:35,640
Speaker 1: You get something that works pretty well as long as

495
00:25:35,640 --> 00:25:38,280
Speaker 1: it doesn't have any interactions. As long as that electron

496
00:25:38,359 --> 00:25:41,439
Speaker 1: is not interacting with any other particles, it's mostly just

497
00:25:41,480 --> 00:25:44,520
Speaker 1: ignoring them, then yeah, you get something that's correct.

498
00:25:44,320 --> 00:25:46,119
Speaker 6: Like it's going to follow the same path as a

499
00:25:46,119 --> 00:25:46,640
Speaker 6: little rock.

500
00:25:47,040 --> 00:25:49,360
Speaker 1: Yes, as long as it's not interacting. But if it's

501
00:25:49,359 --> 00:25:51,680
Speaker 1: in a soup of other electrons and charged particles and

502
00:25:51,720 --> 00:25:55,119
Speaker 1: it's interacting with those, then boom, it's quantum nature becomes

503
00:25:55,200 --> 00:26:00,560
Speaker 1: important and those quantum effects dwarf gravity. They're completely take over.

504
00:26:01,119 --> 00:26:03,639
Speaker 1: So you can either ignore the quantum effects and just

505
00:26:03,680 --> 00:26:06,280
Speaker 1: do the gravity, or you can ignore the gravity and

506
00:26:06,520 --> 00:26:09,840
Speaker 1: just do the quantum effects. For an electron, only one

507
00:26:09,880 --> 00:26:12,720
Speaker 1: of those is relevant at a time, and that's why

508
00:26:12,800 --> 00:26:15,480
Speaker 1: you don't need quantum gravity to think about electrons. You

509
00:26:15,520 --> 00:26:19,240
Speaker 1: can do either quantum mechanics or gravity. They're never both

510
00:26:19,359 --> 00:26:20,600
Speaker 1: relevant at the same time.

511
00:26:20,960 --> 00:26:23,159
Speaker 6: But I guess to an approximation. So then when do

512
00:26:23,200 --> 00:26:25,040
Speaker 6: you get into trouble? Like when is it a problem

513
00:26:25,080 --> 00:26:27,560
Speaker 6: that these two are not unified? But what's the scenario,

514
00:26:27,680 --> 00:26:30,800
Speaker 6: Like it's in gravitational orbit around the Earth, the electron

515
00:26:31,040 --> 00:26:33,399
Speaker 6: is and it's sort of a little bit interacting with

516
00:26:33,440 --> 00:26:35,719
Speaker 6: another electron. Then it's like we don't know what to do.

517
00:26:35,920 --> 00:26:38,439
Speaker 1: As long as it has a quantum interaction, that's just

518
00:26:38,480 --> 00:26:41,520
Speaker 1: going to dominate because the quantum forces are so much

519
00:26:41,600 --> 00:26:44,800
Speaker 1: more powerful than gravity. You know, they're like ten to

520
00:26:44,840 --> 00:26:47,400
Speaker 1: the thirty times as powerful as gravity.

521
00:26:47,720 --> 00:26:50,240
Speaker 6: But like, what if it's like ten to thirty one

522
00:26:50,359 --> 00:26:53,520
Speaker 6: times further away, wouldn't it be at the same level

523
00:26:53,520 --> 00:26:54,080
Speaker 6: of gravity.

524
00:26:54,240 --> 00:26:57,480
Speaker 1: I mean gravity falls with distance, just like quantum forces do. Right,

525
00:26:57,640 --> 00:26:59,800
Speaker 1: So it's not a matter of distance, it's a matter

526
00:26:59,840 --> 00:27:02,879
Speaker 1: of the mass to charge ratio. Like if you have

527
00:27:02,880 --> 00:27:06,880
Speaker 1: two electrons, they feel a very strong electromagnetic repulsion because

528
00:27:06,880 --> 00:27:10,160
Speaker 1: of their charge. They don't feel a very strong gravitational

529
00:27:10,160 --> 00:27:13,639
Speaker 1: attraction because of their mass. The electromagnetic force there is

530
00:27:13,680 --> 00:27:16,160
Speaker 1: always more powerful at any distance.

531
00:27:16,359 --> 00:27:18,560
Speaker 6: I thought maybe the scenario you're trying to paint was like,

532
00:27:18,600 --> 00:27:21,120
Speaker 6: I have an electron out there in space, and it's

533
00:27:21,119 --> 00:27:24,480
Speaker 6: been attracted by gravity to the giant Earth, but maybe

534
00:27:24,480 --> 00:27:27,840
Speaker 6: it's also sort of being repelled by another electron that's nearby,

535
00:27:28,280 --> 00:27:29,840
Speaker 6: and so then we don't know what's going to happen.

536
00:27:30,119 --> 00:27:32,439
Speaker 1: You have a scenario we have a single electron orbiting

537
00:27:32,480 --> 00:27:35,560
Speaker 1: the Earth, and then some very distant electron is very

538
00:27:35,600 --> 00:27:38,479
Speaker 1: gently pushing on it with the same power as the

539
00:27:38,640 --> 00:27:39,920
Speaker 1: gravity of the entire Earth.

540
00:27:40,200 --> 00:27:42,800
Speaker 6: Yes, Is that like the scenario that you run into

541
00:27:42,800 --> 00:27:44,719
Speaker 6: problems or can you still handle it?

542
00:27:45,240 --> 00:27:48,440
Speaker 1: No, that's a cool idea. That's a scenario where gravity

543
00:27:48,600 --> 00:27:51,199
Speaker 1: and conon forces are at the same level and so

544
00:27:51,400 --> 00:27:53,680
Speaker 1: you can't ignore one of them. You have to take

545
00:27:53,720 --> 00:27:55,919
Speaker 1: both into account, and we don't know how to do

546
00:27:55,960 --> 00:27:58,920
Speaker 1: that prediction. That kind of experiment is also pretty hard

547
00:27:58,960 --> 00:28:02,680
Speaker 1: to realize because you need an isolated electron affected by

548
00:28:02,800 --> 00:28:06,560
Speaker 1: only one other electron that's super far away, So it's

549
00:28:06,560 --> 00:28:09,119
Speaker 1: not like practically something we could set up. Otherwise that

550
00:28:09,160 --> 00:28:11,000
Speaker 1: would be really awesome. It would tell us something about

551
00:28:11,080 --> 00:28:11,880
Speaker 1: quantum gravity.

552
00:28:11,960 --> 00:28:14,760
Speaker 6: Yeah, yeah, but that's a physical problem about a physics problem,

553
00:28:14,880 --> 00:28:17,000
Speaker 6: so we don't you know, are couch surfing and Danna

554
00:28:17,080 --> 00:28:17,800
Speaker 6: Jones doesn't care.

555
00:28:17,880 --> 00:28:19,760
Speaker 1: The other way to tackle this is to say, well,

556
00:28:19,760 --> 00:28:22,440
Speaker 1: what if you have a really really massive quantum particle

557
00:28:22,680 --> 00:28:25,920
Speaker 1: particle that is feeling quantum forces but actually has enough

558
00:28:25,960 --> 00:28:29,200
Speaker 1: mass that its gravity can't be ignored, and that's when

559
00:28:29,240 --> 00:28:30,240
Speaker 1: you end up in a black hole?

560
00:28:30,880 --> 00:28:33,560
Speaker 6: All right, So can you be more specific about what

561
00:28:33,600 --> 00:28:36,240
Speaker 6: the problem is, like, we don't know how to tell

562
00:28:36,280 --> 00:28:38,480
Speaker 6: what the particle is going to do next, or we

563
00:28:38,520 --> 00:28:40,800
Speaker 6: can't predict how it's going to interact. Can you're describing

564
00:28:40,920 --> 00:28:43,360
Speaker 6: words what the problem is at the indec scenarios.

565
00:28:43,480 --> 00:28:46,040
Speaker 1: The problem is that our two theories general relativity and

566
00:28:46,120 --> 00:28:49,320
Speaker 1: quantum mechanics make different predictions about what's going to happen.

567
00:28:50,000 --> 00:28:51,800
Speaker 6: What do you mean, Like like one theory says that

568
00:28:51,840 --> 00:28:53,480
Speaker 6: the electron is going to turn right, and the other

569
00:28:53,520 --> 00:28:55,120
Speaker 6: theory says the electric is going to turn left.

570
00:28:55,480 --> 00:28:58,040
Speaker 1: Yeah. For example, general relativity is a classical theory, and

571
00:28:58,080 --> 00:29:01,720
Speaker 1: so it assumes electrons have very definitive location at every

572
00:29:01,760 --> 00:29:05,160
Speaker 1: point in time, whereas quantum mechanics says no, there's probabilistic

573
00:29:05,160 --> 00:29:08,320
Speaker 1: and you can get things like interference. General relativity says,

574
00:29:08,360 --> 00:29:10,320
Speaker 1: I'm ignoring all that interference stuff, and it's going to

575
00:29:10,360 --> 00:29:13,240
Speaker 1: make a prediction based on treating the electron like it's

576
00:29:13,280 --> 00:29:15,840
Speaker 1: a little rock flying through space. So they're going to

577
00:29:15,880 --> 00:29:18,200
Speaker 1: come up with very different predictions for what's going to happen.

578
00:29:18,480 --> 00:29:21,080
Speaker 1: General relativity doesn't allowed for like entanglement or any of

579
00:29:21,120 --> 00:29:25,120
Speaker 1: the other important quantum effects that totally control what happens

580
00:29:25,160 --> 00:29:25,880
Speaker 1: to an electron.

581
00:29:26,120 --> 00:29:29,440
Speaker 6: I see, because quantum mechanics also might change which direction

582
00:29:29,560 --> 00:29:30,360
Speaker 6: the electron goes.

583
00:29:30,400 --> 00:29:34,840
Speaker 1: Absolutely, Yeah. Electromagnetism is a quantum effect, right. Those forces,

584
00:29:34,880 --> 00:29:37,560
Speaker 1: all the forces in the universe that cause acceleration, the

585
00:29:37,560 --> 00:29:41,400
Speaker 1: weak force, electromagnetism, the strong force, these are all quantum effects.

586
00:29:41,400 --> 00:29:45,200
Speaker 1: They all operate on the probabilistic wave functions that control

587
00:29:45,280 --> 00:29:49,240
Speaker 1: these particles. General relativity ignores those. So you ask quantum

588
00:29:49,280 --> 00:29:52,160
Speaker 1: mechanics and gr what's going to happen to this electron.

589
00:29:52,440 --> 00:29:54,240
Speaker 1: They disagree about what's going to happen.

590
00:29:54,760 --> 00:29:56,440
Speaker 6: Well, maybe this is the point where we have to

591
00:29:56,480 --> 00:29:59,080
Speaker 6: get more into the math, because you know, as a

592
00:29:59,120 --> 00:30:01,280
Speaker 6: lay person, I might say, like, can you just add

593
00:30:01,280 --> 00:30:04,640
Speaker 6: these two things? Like why can't just have a particle

594
00:30:05,080 --> 00:30:08,680
Speaker 6: that gravity pulls on its average position and so the

595
00:30:08,720 --> 00:30:12,160
Speaker 6: average position curves according to gravity, but then where it

596
00:30:12,280 --> 00:30:14,800
Speaker 6: is exactly might be fuzzy due to quantum mechanics.

597
00:30:14,880 --> 00:30:16,640
Speaker 1: Yes, So what you're trying to do right now is

598
00:30:16,720 --> 00:30:18,720
Speaker 1: come up with a theory of quantum gravity. You're trying

599
00:30:18,720 --> 00:30:20,680
Speaker 1: to say, can I get all the good bits of

600
00:30:20,720 --> 00:30:23,560
Speaker 1: general relativity and all the good bits of quantum mechanics

601
00:30:23,560 --> 00:30:26,120
Speaker 1: and smooth them together to make a theory of quantum

602
00:30:26,160 --> 00:30:29,080
Speaker 1: gravity that makes one prediction right? And so that's the

603
00:30:29,080 --> 00:30:32,040
Speaker 1: topic of the episode. Why is that so hard? And

604
00:30:32,040 --> 00:30:34,320
Speaker 1: people have been working on for one hundred years. It

605
00:30:34,440 --> 00:30:36,880
Speaker 1: sounds straightforward, but there's a bunch of reasons why it's

606
00:30:36,920 --> 00:30:39,520
Speaker 1: actually quite tricky. One of them is the problem you

607
00:30:39,600 --> 00:30:42,360
Speaker 1: just mentioned, which is this question of like space and

608
00:30:42,400 --> 00:30:46,360
Speaker 1: time and probability. You know, quantum particles don't have definitive

609
00:30:46,400 --> 00:30:51,760
Speaker 1: locations and general relativity doesn't allow for probabilities in space time.

610
00:30:52,200 --> 00:30:54,440
Speaker 1: What you just described is like, well, what if the

611
00:30:54,480 --> 00:30:57,360
Speaker 1: electron is allowed to have a probability being here or there?

612
00:30:57,440 --> 00:31:00,000
Speaker 1: And so we just say, like space has a probability

613
00:31:00,160 --> 00:31:03,920
Speaker 1: being curved here and the probability of being curved there. Right,

614
00:31:04,280 --> 00:31:07,920
Speaker 1: that's like a pretty deep change to how general relativity works,

615
00:31:08,160 --> 00:31:11,000
Speaker 1: and the mathematics of it breaks down, Like general relativity

616
00:31:11,000 --> 00:31:13,280
Speaker 1: doesn't allow for those probabilities.

617
00:31:13,880 --> 00:31:16,080
Speaker 6: What do you mean, like doesn't allow it? Like you

618
00:31:16,160 --> 00:31:18,480
Speaker 6: just don't know how to write it down, or like

619
00:31:18,800 --> 00:31:21,880
Speaker 6: you get nonsensical answers, or it's like trying to fit

620
00:31:21,960 --> 00:31:23,960
Speaker 6: a square peg in a round hole. You know, I am

621
00:31:23,920 --> 00:31:26,600
Speaker 6: I trying to use fractions to you know, compute things

622
00:31:26,600 --> 00:31:28,440
Speaker 6: to a certain decimal point or something.

623
00:31:28,760 --> 00:31:31,520
Speaker 1: Yeah, the mathematics of general relativity is hard. You know.

624
00:31:31,560 --> 00:31:35,200
Speaker 1: It took Einstein like ten years to figure out how

625
00:31:35,240 --> 00:31:37,720
Speaker 1: to wrangle these equations to make any sense of them.

626
00:31:38,080 --> 00:31:40,640
Speaker 1: He had this idea that maybe space was curved, and

627
00:31:40,680 --> 00:31:43,320
Speaker 1: that was explaining what gravity really was, but to make

628
00:31:43,360 --> 00:31:46,120
Speaker 1: the math work to even Einstein in a decade, and

629
00:31:46,120 --> 00:31:47,880
Speaker 1: it takes a lot of people a lot of time

630
00:31:47,920 --> 00:31:50,280
Speaker 1: to understand and to wrestle with the equations which turn

631
00:31:50,360 --> 00:31:53,160
Speaker 1: out to be really, really complicated. It's not like one

632
00:31:53,160 --> 00:31:56,320
Speaker 1: equation for a general relativity that says more mass means

633
00:31:56,360 --> 00:32:00,640
Speaker 1: more curvature. It's a matrix of equations. It's like sixteen

634
00:32:00,720 --> 00:32:04,240
Speaker 1: coupled equations which are really hairy, and if you add

635
00:32:04,280 --> 00:32:07,040
Speaker 1: to those the probability that space is may be curved

636
00:32:07,040 --> 00:32:11,000
Speaker 1: here and maybe curved there, it increases the complexity exponentially,

637
00:32:11,240 --> 00:32:13,760
Speaker 1: and it makes those equations impossible to even write down.

638
00:32:13,800 --> 00:32:16,480
Speaker 1: We don't know how to write down equations that both

639
00:32:16,560 --> 00:32:20,800
Speaker 1: describe space as a curvature of this differential geometric manifold

640
00:32:21,200 --> 00:32:24,160
Speaker 1: and allow for probabilities. Like, we just don't have the

641
00:32:24,200 --> 00:32:26,560
Speaker 1: tools for it. It might be that somebody out there

642
00:32:26,600 --> 00:32:30,880
Speaker 1: is developing some cool theory of probabilistic manifolds that later

643
00:32:30,960 --> 00:32:33,280
Speaker 1: will be able to slip in to build the theory

644
00:32:33,280 --> 00:32:35,920
Speaker 1: of quantum gravity. But it's like we need a power

645
00:32:35,920 --> 00:32:37,560
Speaker 1: tool and all we have is a handsaw.

646
00:32:37,720 --> 00:32:39,160
Speaker 6: Yeah, Like you say, like if we just don't have

647
00:32:39,240 --> 00:32:42,440
Speaker 6: the right tools that will both fit a square peg

648
00:32:42,480 --> 00:32:43,440
Speaker 6: and a round hole.

649
00:32:43,240 --> 00:32:44,760
Speaker 1: And we don't know if we're missing the right tool.

650
00:32:44,800 --> 00:32:47,280
Speaker 1: Maybe that's just the wrong direction, right. It could be

651
00:32:47,360 --> 00:32:49,520
Speaker 1: that that's not the right way to try to build

652
00:32:49,520 --> 00:32:52,320
Speaker 1: the theory of quantum gravity. But a lot of times

653
00:32:52,360 --> 00:32:55,360
Speaker 1: it is the case that progress in mathematics is limiting

654
00:32:55,400 --> 00:32:58,600
Speaker 1: progress in physics. Einstein was only able to build general

655
00:32:58,600 --> 00:33:02,240
Speaker 1: relativity because the theory is differential geometry had been developed

656
00:33:02,280 --> 00:33:05,800
Speaker 1: like ten fifteen years earlier by mathematicians who didn't care

657
00:33:05,840 --> 00:33:08,600
Speaker 1: at all about gravity or physics. They just thought it

658
00:33:08,640 --> 00:33:11,600
Speaker 1: was cool to think about like wiggly shapes in their mind,

659
00:33:11,800 --> 00:33:13,640
Speaker 1: and so this kind of stuff happens all the time.

660
00:33:14,440 --> 00:33:16,880
Speaker 6: I see you're saying, it's all the mathematicians felt like

661
00:33:16,920 --> 00:33:18,440
Speaker 6: they're holding you back. Man.

662
00:33:18,640 --> 00:33:21,160
Speaker 1: Math is the language of physics, and in the end,

663
00:33:21,280 --> 00:33:24,520
Speaker 1: it's mathematical problems that are preventing us from building theories

664
00:33:24,520 --> 00:33:28,120
Speaker 1: of quantum gravity. And what you described is basically trying

665
00:33:28,200 --> 00:33:31,280
Speaker 1: to make space quantum mechanical. You can also go the

666
00:33:31,360 --> 00:33:33,040
Speaker 1: other direction, and you can say, well, what if we

667
00:33:33,120 --> 00:33:36,440
Speaker 1: try to make gravity itself quantum mechanical. What if we

668
00:33:36,480 --> 00:33:39,440
Speaker 1: try to describe the theory of gravity as a quantum

669
00:33:39,520 --> 00:33:43,480
Speaker 1: force instead of this whole crazy curvature of space and time,

670
00:33:43,840 --> 00:33:46,040
Speaker 1: and then you run into a completely different kind of

671
00:33:46,080 --> 00:33:47,600
Speaker 1: mathematical m I see.

672
00:33:47,720 --> 00:33:49,920
Speaker 6: I think what you're saying is like that each of

673
00:33:49,960 --> 00:33:52,360
Speaker 6: these two theories work, but only if they ignore each other.

674
00:33:52,520 --> 00:33:55,800
Speaker 6: Like quantum mechanics assume as that space doesn't bend and

675
00:33:55,840 --> 00:33:59,400
Speaker 6: there is no gravity, basically gravity doesn't exist to quantum mechanics,

676
00:34:00,120 --> 00:34:03,800
Speaker 6: general relativity assumes that things are not fuzzy at any

677
00:34:03,880 --> 00:34:06,760
Speaker 6: level exactly, which works for a lot of situations, but

678
00:34:07,040 --> 00:34:10,280
Speaker 6: in some situations you have to take them into account

679
00:34:10,280 --> 00:34:11,240
Speaker 6: both at the same time.

680
00:34:11,160 --> 00:34:14,200
Speaker 1: Exactly, and it's amazing that both of them work. They

681
00:34:14,200 --> 00:34:16,640
Speaker 1: tell very different stories about what's really happening in the universe,

682
00:34:17,120 --> 00:34:20,400
Speaker 1: and in almost every scenario you can ignore one, right.

683
00:34:21,080 --> 00:34:22,960
Speaker 1: It's like you have two friends that are like different

684
00:34:23,000 --> 00:34:24,920
Speaker 1: kinds of movies or something, and most of the time

685
00:34:24,960 --> 00:34:26,759
Speaker 1: you can just ignore one friend and listen to the

686
00:34:26,800 --> 00:34:30,440
Speaker 1: other friend. But sometimes they have opinions about the same

687
00:34:30,520 --> 00:34:32,000
Speaker 1: kind of movie, and you're like, well, is this movie

688
00:34:32,000 --> 00:34:33,680
Speaker 1: good or bad? I don't know who to listen to.

689
00:34:34,280 --> 00:34:37,400
Speaker 1: And for general relativity and quantum mechanics. Currently, they only

690
00:34:37,440 --> 00:34:41,799
Speaker 1: overlap in places we cannot see inside black holes, so

691
00:34:41,840 --> 00:34:44,719
Speaker 1: we don't know who's fundamentally right, or if either of

692
00:34:44,760 --> 00:34:45,319
Speaker 1: them are right.

693
00:34:46,160 --> 00:34:48,320
Speaker 6: I see. It's like having a friend who only watches

694
00:34:48,320 --> 00:34:51,160
Speaker 6: sci fi movies, yeah, and then having another friend who

695
00:34:51,200 --> 00:34:54,400
Speaker 6: only watches romantic comedies. And usually you can have perfectly

696
00:34:54,440 --> 00:34:57,840
Speaker 6: good conversations with either of them. But let's say science

697
00:34:57,840 --> 00:34:59,279
Speaker 6: fiction wrap the comedy comes out.

698
00:35:00,000 --> 00:35:02,640
Speaker 1: Now there's exactly exactly right. Now you can't hang out

699
00:35:02,680 --> 00:35:04,560
Speaker 1: with your friends anymore, right, boom the universe.

700
00:35:05,440 --> 00:35:09,520
Speaker 6: You gotta stop watching movies. You can stage your couch

701
00:35:09,560 --> 00:35:13,840
Speaker 6: and just do physics and math all day. Has this

702
00:35:13,880 --> 00:35:14,719
Speaker 6: ho already happened to you?

703
00:35:14,760 --> 00:35:15,000
Speaker 8: Ben?

704
00:35:16,200 --> 00:35:19,360
Speaker 1: I think Passengers? This was not a sci fi romantic comedy.

705
00:35:19,480 --> 00:35:22,279
Speaker 6: Oh, there you go. And that was very controversial, man,

706
00:35:22,360 --> 00:35:26,480
Speaker 6: Exactly nobody likes that. If we don't have the math

707
00:35:26,680 --> 00:35:30,200
Speaker 6: tools or framework or theories that let us tackle these

708
00:35:30,200 --> 00:35:31,719
Speaker 6: two things at the same time, what are some other

709
00:35:31,719 --> 00:35:34,000
Speaker 6: ways that make it hard to unify these two things.

710
00:35:34,200 --> 00:35:36,520
Speaker 1: So a really popular approach is to trying to make

711
00:35:36,520 --> 00:35:40,120
Speaker 1: a theory of quantum gravity that has a graviton. Say

712
00:35:40,239 --> 00:35:42,920
Speaker 1: you know Einstein, that was cute. We like your idea

713
00:35:42,920 --> 00:35:45,800
Speaker 1: of Kurt spacetime. It's pretty, but maybe it's just fundamentally

714
00:35:45,840 --> 00:35:48,279
Speaker 1: the wrong direction. Maybe if you zoom in, what really

715
00:35:48,320 --> 00:35:50,640
Speaker 1: is happening is that gravity is a force and it's

716
00:35:50,680 --> 00:35:54,920
Speaker 1: exchanging gravitons, and I mean, then we can describe the

717
00:35:54,960 --> 00:35:57,440
Speaker 1: whole theory of gravity back sort of as like a

718
00:35:57,520 --> 00:36:01,040
Speaker 1: quantized version of Newton's theory. And people have tried to

719
00:36:01,080 --> 00:36:03,000
Speaker 1: do this because that'd be pretty right. If we could

720
00:36:03,000 --> 00:36:05,080
Speaker 1: just like add gravity to the standard model and have

721
00:36:05,120 --> 00:36:08,919
Speaker 1: another particle and ignore this whole curvature business, that would

722
00:36:08,960 --> 00:36:09,400
Speaker 1: be cool.

723
00:36:09,520 --> 00:36:11,120
Speaker 6: So that would be going back to the idea that

724
00:36:11,120 --> 00:36:13,840
Speaker 6: gravity is a force, not a bending of space and

725
00:36:13,920 --> 00:36:14,720
Speaker 6: time exactly.

726
00:36:14,920 --> 00:36:17,880
Speaker 1: So to tell philosophically a very different story from what

727
00:36:17,920 --> 00:36:20,840
Speaker 1: Einstein is telling us about how the universe works, they

728
00:36:20,840 --> 00:36:23,400
Speaker 1: would say there is no curvature. There are these tiny,

729
00:36:23,440 --> 00:36:26,680
Speaker 1: little invisible gravitons being passed back and forth. The same

730
00:36:26,719 --> 00:36:29,719
Speaker 1: way that like electromagnetism we think about in terms of

731
00:36:29,920 --> 00:36:33,000
Speaker 1: electric fields that are sort of like virtual photons being

732
00:36:33,040 --> 00:36:35,840
Speaker 1: passed back and forth, we can think of gravity in

733
00:36:35,960 --> 00:36:39,319
Speaker 1: terms of gravitons being passed back and forth. So that's

734
00:36:39,360 --> 00:36:42,479
Speaker 1: one direction. The problem is nobody can make that math

735
00:36:42,600 --> 00:36:45,400
Speaker 1: work either. When you do the calculations there and you

736
00:36:45,440 --> 00:36:47,800
Speaker 1: ask like, well, what happens if you try to collide

737
00:36:47,800 --> 00:36:51,360
Speaker 1: two black holes together or even two protons together, you

738
00:36:51,400 --> 00:36:54,799
Speaker 1: get nonsense answers. You get answers like, well, the probability

739
00:36:54,800 --> 00:36:57,279
Speaker 1: of this happening is one hundred and fifty percent, and

740
00:36:57,320 --> 00:37:00,160
Speaker 1: the probability of that happening is one thousand percent, just

741
00:37:00,200 --> 00:37:02,799
Speaker 1: like numbers that do not make sense. You can't have

742
00:37:02,880 --> 00:37:07,400
Speaker 1: probabilities greater than one. But that's what these calculations spit.

743
00:37:07,160 --> 00:37:09,400
Speaker 6: Out, Like if you assume a gravitin exists, then you

744
00:37:09,400 --> 00:37:13,040
Speaker 6: get these weird answers, but more fundamentally, like you're ignoring

745
00:37:13,280 --> 00:37:16,400
Speaker 6: general relativity, right, You're ignoring things that a lot of

746
00:37:16,400 --> 00:37:19,440
Speaker 6: experiments have verified that Eisin was right, And so you're

747
00:37:19,480 --> 00:37:21,719
Speaker 6: sort of not really solving the problem, right, are you.

748
00:37:21,920 --> 00:37:23,520
Speaker 1: Well, you'd have to think about it as an upgrade

749
00:37:23,560 --> 00:37:26,359
Speaker 1: to general relativity. You'd have to reproduce all the predictions

750
00:37:26,400 --> 00:37:29,080
Speaker 1: of general relativity. So you need to develop a theory

751
00:37:29,120 --> 00:37:32,520
Speaker 1: of gravitons, which when you zoom out, looks a lot

752
00:37:32,680 --> 00:37:35,439
Speaker 1: like general relativity, and that people actually can do. There

753
00:37:35,480 --> 00:37:39,560
Speaker 1: are theories of quantum gravity that involve graviton exchange that

754
00:37:39,640 --> 00:37:41,799
Speaker 1: when you zoom out, look a lot like general.

755
00:37:41,480 --> 00:37:44,200
Speaker 6: Relativity, so space time is not being bent.

756
00:37:44,360 --> 00:37:46,360
Speaker 1: Yeah, they tell a different story, but they make the

757
00:37:46,360 --> 00:37:49,839
Speaker 1: same predictions about like the motions of objects.

758
00:37:49,680 --> 00:37:53,800
Speaker 6: Including things like gravitational ways and frame dragging and all that, all.

759
00:37:53,680 --> 00:37:55,799
Speaker 1: That kind of stuff. The problem is what happens at

760
00:37:55,800 --> 00:37:57,440
Speaker 1: the small scale. When you try to think about like

761
00:37:57,800 --> 00:38:00,879
Speaker 1: when two particles scatter against each other or when two

762
00:38:00,920 --> 00:38:04,080
Speaker 1: black holes are being eaten, then this theory breaks down.

763
00:38:04,560 --> 00:38:06,600
Speaker 6: But generativity still works for those.

764
00:38:06,719 --> 00:38:09,319
Speaker 1: General relativity still works for those. But we think it's wrong, right.

765
00:38:09,360 --> 00:38:12,239
Speaker 1: General relativity, we think is giving the wrong answer for

766
00:38:12,320 --> 00:38:14,880
Speaker 1: what happens when two protons collide or what's at the

767
00:38:14,880 --> 00:38:17,400
Speaker 1: heart of a black hole, because it's ignoring the quantum

768
00:38:17,400 --> 00:38:20,319
Speaker 1: mechanical effects. We try to build a theory of quantum

769
00:38:20,400 --> 00:38:23,880
Speaker 1: gravity that has gravitons and explains all of general relativity

770
00:38:24,200 --> 00:38:28,040
Speaker 1: and gives you a gravitational quantum mechanical prediction for what

771
00:38:28,120 --> 00:38:30,960
Speaker 1: happens when two particles collide or two black holes collide.

772
00:38:31,080 --> 00:38:32,840
Speaker 1: Then you get all sorts of nonsense. You get all

773
00:38:32,920 --> 00:38:35,640
Speaker 1: sorts of infinities that we don't know how to wrangle.

774
00:38:35,920 --> 00:38:39,120
Speaker 6: M I see, so graviton not a great ivan, you

775
00:38:39,120 --> 00:38:40,520
Speaker 6: are one that hasn't worked so far.

776
00:38:40,960 --> 00:38:44,680
Speaker 1: Yeah, exactly. There are also sort of fundamental problems we

777
00:38:44,800 --> 00:38:47,440
Speaker 1: just don't know how to solve for quantum gravity, like

778
00:38:47,960 --> 00:38:51,359
Speaker 1: deep inconsistencies between the picture of the universe we get

779
00:38:51,360 --> 00:38:53,840
Speaker 1: from general relativity and the picture of the universe we

780
00:38:53,880 --> 00:38:56,960
Speaker 1: get from quantum mechanics about how physics should work that

781
00:38:57,040 --> 00:38:59,480
Speaker 1: we just don't know how to reconcile. What do you mean, Like,

782
00:38:59,520 --> 00:39:01,920
Speaker 1: what like a deep principle in physics is this idea

783
00:39:01,960 --> 00:39:05,120
Speaker 1: of locality that things should be near each other to

784
00:39:05,200 --> 00:39:08,280
Speaker 1: affect each other, that you shouldn't have like an electron

785
00:39:08,360 --> 00:39:11,560
Speaker 1: over here affecting something really really far away in the universe,

786
00:39:12,200 --> 00:39:15,759
Speaker 1: especially in quantum mechanics, and in quantum mechanics, we have

787
00:39:15,800 --> 00:39:20,320
Speaker 1: this deep connection between the distances between things and their energies.

788
00:39:20,920 --> 00:39:23,600
Speaker 1: Like the reason that we use the Large Hadron Collider

789
00:39:23,680 --> 00:39:26,439
Speaker 1: to study really really really tiny things is you need

790
00:39:26,760 --> 00:39:31,160
Speaker 1: really high energy to study really small distance scales, like

791
00:39:31,280 --> 00:39:33,920
Speaker 1: things that have a lot of energy interact with each

792
00:39:33,960 --> 00:39:35,040
Speaker 1: other very very.

793
00:39:34,800 --> 00:39:39,040
Speaker 6: Closely, because if things have low energy, then they don't

794
00:39:39,040 --> 00:39:40,480
Speaker 6: interact with the things around them.

795
00:39:40,680 --> 00:39:42,719
Speaker 1: If things have low energy, then they can interact with

796
00:39:42,719 --> 00:39:45,520
Speaker 1: stuff that's further away. Another way to think about it

797
00:39:45,560 --> 00:39:48,279
Speaker 1: is in terms of the wavelength of stuff. You know

798
00:39:48,360 --> 00:39:51,160
Speaker 1: that you need like really high energy photons to see

799
00:39:51,160 --> 00:39:54,279
Speaker 1: really really small stuff. With lower energy photons they have

800
00:39:54,320 --> 00:39:58,480
Speaker 1: a longer wavelength. You can't like resolve small details. That's why,

801
00:39:58,520 --> 00:40:00,399
Speaker 1: for example, when you want pictures of roos, the really

802
00:40:00,440 --> 00:40:04,680
Speaker 1: tiny stuff, you use high frequency photons. You go beyond

803
00:40:04,680 --> 00:40:07,800
Speaker 1: that to use like electrons to take pictures of atoms

804
00:40:07,800 --> 00:40:10,000
Speaker 1: for example. So you want to see the universe on

805
00:40:10,040 --> 00:40:13,279
Speaker 1: a really small scale, you need to use really high energy.

806
00:40:13,000 --> 00:40:16,080
Speaker 6: Probes, maybe to say high frequency instead of high energy.

807
00:40:16,239 --> 00:40:19,800
Speaker 1: Yeah, energy and frequency very closely connected. In quantum mechanics,

808
00:40:19,840 --> 00:40:24,560
Speaker 1: you need very high frequency stuff to see really short distances. Okay,

809
00:40:24,719 --> 00:40:28,080
Speaker 1: In general relativity they have the opposite relationship. As you

810
00:40:28,160 --> 00:40:32,600
Speaker 1: add energy to something in general relativity, then its influence

811
00:40:32,719 --> 00:40:37,120
Speaker 1: grows to longer distances. So quantum mechanics, higher energy means

812
00:40:37,120 --> 00:40:41,799
Speaker 1: shorter distances. In general relativity, higher energy means larger distances.

813
00:40:42,320 --> 00:40:45,160
Speaker 1: Like think about what happens to a black hole's radius

814
00:40:45,440 --> 00:40:47,919
Speaker 1: as you add energy to a black hole. Black hole

815
00:40:47,960 --> 00:40:51,640
Speaker 1: gets bigger. You add more energy, black hole keeps getting bigger.

816
00:40:51,960 --> 00:40:55,239
Speaker 1: The short styled radius, the distance from the singularity to

817
00:40:55,239 --> 00:40:57,879
Speaker 1: the event horizon, just keeps growing as the black hole

818
00:40:57,920 --> 00:41:01,439
Speaker 1: gets more massive. So somehow relativity doesn't have the same

819
00:41:01,480 --> 00:41:06,200
Speaker 1: relationship between energy and frequency and the distances involved. They

820
00:41:06,200 --> 00:41:10,319
Speaker 1: have like this deeply opposite relationship. This might sound like

821
00:41:10,360 --> 00:41:14,120
Speaker 1: sort of weirdly philosophically handwavy to you, but it sort

822
00:41:14,160 --> 00:41:14,920
Speaker 1: of tells.

823
00:41:14,640 --> 00:41:17,640
Speaker 6: You about that not at all. I don't know what

824
00:41:17,719 --> 00:41:18,000
Speaker 6: you mean.

825
00:41:18,880 --> 00:41:21,239
Speaker 1: But the reason it's important is that it tells us

826
00:41:21,239 --> 00:41:23,560
Speaker 1: that these two theories have like a fundamentally different sort

827
00:41:23,600 --> 00:41:26,840
Speaker 1: of philosophical foundation. Like one of them is very very local,

828
00:41:26,960 --> 00:41:29,560
Speaker 1: the other one is very non local. So when we

829
00:41:29,600 --> 00:41:32,080
Speaker 1: go to make a theory of quantum gravity, we're like, hmm,

830
00:41:32,080 --> 00:41:34,319
Speaker 1: these two things are kind of like very different. How

831
00:41:34,360 --> 00:41:36,400
Speaker 1: do we bring them together? It's like, how do you

832
00:41:36,440 --> 00:41:39,439
Speaker 1: get your science fiction fan friend and your rom com

833
00:41:39,520 --> 00:41:42,239
Speaker 1: fan friend together into a single movie If they have

834
00:41:42,440 --> 00:41:45,799
Speaker 1: just like really opposing needs for pacing and jokes and

835
00:41:45,880 --> 00:41:49,759
Speaker 1: whatever in the movie, it might be fundamentally impossible. If

836
00:41:49,760 --> 00:41:52,040
Speaker 1: these two things are so deeply in conflict.

837
00:41:52,280 --> 00:41:54,440
Speaker 6: It sounds like you're just kind of maybe saying the

838
00:41:54,440 --> 00:41:57,279
Speaker 6: same thing we talked about before, which is, like, you know,

839
00:41:57,360 --> 00:42:00,680
Speaker 6: quantum gravity is good for things that are small, and

840
00:42:00,840 --> 00:42:03,280
Speaker 6: general relativity is good for things that are really big,

841
00:42:03,800 --> 00:42:06,719
Speaker 6: but there is a certain overlap between them, and that's

842
00:42:06,719 --> 00:42:07,680
Speaker 6: where you get into trouble.

843
00:42:07,880 --> 00:42:10,600
Speaker 1: Yeah exactly, but I think there's one more layer there, Like,

844
00:42:10,640 --> 00:42:13,680
Speaker 1: imagine you have a singularity so at a tiny little

845
00:42:13,719 --> 00:42:17,080
Speaker 1: spot with a huge amount of mass, right, so it's

846
00:42:17,160 --> 00:42:20,680
Speaker 1: quantum mechanically important, but also has a huge amount of mass.

847
00:42:20,960 --> 00:42:24,560
Speaker 1: General relativity says it affects things really really far away

848
00:42:24,640 --> 00:42:27,600
Speaker 1: because it creates a black hole. Who's event horizon can

849
00:42:27,719 --> 00:42:30,840
Speaker 1: be really really far away. Quantum mechanics says, no, it

850
00:42:30,840 --> 00:42:33,440
Speaker 1: can only interact with stuff really really nearby, because that's

851
00:42:33,520 --> 00:42:35,120
Speaker 1: really really tiny frequency.

852
00:42:35,360 --> 00:42:37,600
Speaker 6: Well, I would say that it can only interact quantum

853
00:42:37,640 --> 00:42:40,279
Speaker 6: mechanically with things that are close by, but then it

854
00:42:40,320 --> 00:42:43,360
Speaker 6: can interact through gravity or general relativity for things that

855
00:42:43,360 --> 00:42:43,959
Speaker 6: are far away.

856
00:42:45,080 --> 00:42:48,960
Speaker 1: Back to the same spot, Yeah, exactly, We're back to

857
00:42:49,000 --> 00:42:51,680
Speaker 1: the same spot that if you have quantum gravity, then

858
00:42:51,719 --> 00:42:54,319
Speaker 1: you don't know, can it only interact nearby in its

859
00:42:54,360 --> 00:42:58,240
Speaker 1: vicinity or can it interact far away as well? Gravity

860
00:42:58,239 --> 00:43:01,279
Speaker 1: says far away, quantum mechanics says nearby. We don't know

861
00:43:01,320 --> 00:43:04,400
Speaker 1: what quantum gravity says. It seems like maybe impossible to

862
00:43:04,440 --> 00:43:06,880
Speaker 1: come up with a theory that satisfies both mm.

863
00:43:07,239 --> 00:43:08,919
Speaker 6: Just like it's impossible to come up with a good

864
00:43:09,040 --> 00:43:12,080
Speaker 6: sci fi rom com exactly.

865
00:43:12,560 --> 00:43:14,000
Speaker 1: They're fundamentally opposed.

866
00:43:14,120 --> 00:43:16,680
Speaker 6: All right, Well, let's dig into some of the other

867
00:43:16,719 --> 00:43:19,920
Speaker 6: ways that make it hard to unify general relativity and

868
00:43:20,000 --> 00:43:35,319
Speaker 6: quantum mechanics. But first, let's take another quick break. All right,

869
00:43:35,360 --> 00:43:39,759
Speaker 6: we're talking about quantum gravity. Can we unite quantum mechanics

870
00:43:39,840 --> 00:43:44,040
Speaker 6: and general relativity which has gravity in it? So far, Daniel,

871
00:43:44,040 --> 00:43:45,239
Speaker 6: you're saying it's really hard.

872
00:43:45,360 --> 00:43:48,279
Speaker 1: It's really hard. Some of the smartest people in the

873
00:43:48,400 --> 00:43:51,480
Speaker 1: universe have tried for decades and failed.

874
00:43:51,320 --> 00:43:53,960
Speaker 6: In the universe. That's a big claim.

875
00:43:54,239 --> 00:43:56,640
Speaker 1: Well, at the smartest people in the universe. It could

876
00:43:56,680 --> 00:43:59,600
Speaker 1: be aliens out there, much smarter than us. I don't know.

877
00:43:59,640 --> 00:44:01,720
Speaker 1: Are they people though? Are aliens people?

878
00:44:02,080 --> 00:44:04,640
Speaker 6: Well, you're assuming that the smartest people on Earth have

879
00:44:04,760 --> 00:44:05,600
Speaker 6: become physicists.

880
00:44:05,640 --> 00:44:08,239
Speaker 1: Oh that's a good point. Yeah, I know that people

881
00:44:08,280 --> 00:44:10,560
Speaker 1: out there who are like Hedge fund bros.

882
00:44:10,640 --> 00:44:14,279
Speaker 6: Yeah, or cartoonist maybe. You know. I'm just saying you're

883
00:44:14,320 --> 00:44:15,720
Speaker 6: sort of making a general assumption.

884
00:44:15,760 --> 00:44:18,239
Speaker 1: Here are you saying you're not a physicist? I think

885
00:44:18,480 --> 00:44:20,919
Speaker 1: years in basically you're a physicist by now.

886
00:44:21,120 --> 00:44:24,759
Speaker 6: Oh, if that's true, then I have a diploma for

887
00:44:24,800 --> 00:44:25,280
Speaker 6: you to sign.

888
00:44:26,160 --> 00:44:28,920
Speaker 1: Yeah, I think we gave you that podcast diploma physics.

889
00:44:29,000 --> 00:44:31,680
Speaker 6: Right, I'm still waiting for that in the mail. It

890
00:44:31,760 --> 00:44:33,759
Speaker 6: must have gotten lost. I guess you sent the right.

891
00:44:34,640 --> 00:44:36,200
Speaker 1: Oh, we sent it. Yeah, you should definitely get a

892
00:44:36,239 --> 00:44:38,560
Speaker 1: physical copy. You do like a discount at dollar story.

893
00:44:39,520 --> 00:44:44,880
Speaker 6: This is an imaginary diploma again for an imaginary field

894
00:44:44,920 --> 00:44:48,120
Speaker 6: of study. All right, So it's hard to combine these

895
00:44:48,120 --> 00:44:51,399
Speaker 6: two big theories. We talked about how the math makes

896
00:44:51,440 --> 00:44:54,440
Speaker 6: it really difficult. The philosophy of them make it really difficult.

897
00:44:54,440 --> 00:44:55,879
Speaker 6: What are some other ways that make it hard?

898
00:44:55,960 --> 00:44:58,600
Speaker 1: People argue about the fundamental story of space and time

899
00:44:59,160 --> 00:45:01,040
Speaker 1: that quantum graph. But you will have to tell us

900
00:45:01,480 --> 00:45:05,040
Speaker 1: because quantum mechanics and general relativity really do tell very

901
00:45:05,160 --> 00:45:08,239
Speaker 1: very different stories. Here in quantum mechanics, we have kind

902
00:45:08,280 --> 00:45:10,600
Speaker 1: of like a Newtonian view of space and time. We

903
00:45:10,680 --> 00:45:15,240
Speaker 1: say space and time they're backdrops, they're absolute. They're fixed,

904
00:45:15,480 --> 00:45:17,960
Speaker 1: and we put quantum fields on top of that space

905
00:45:18,000 --> 00:45:21,520
Speaker 1: and time. We assume that space and time already exists somehow,

906
00:45:21,920 --> 00:45:24,560
Speaker 1: and we say that this quantum fields in that space

907
00:45:24,560 --> 00:45:27,280
Speaker 1: and time, and those fields operate and they're part of space.

908
00:45:27,520 --> 00:45:30,319
Speaker 1: But we don't ask about where space comes from or

909
00:45:30,320 --> 00:45:32,520
Speaker 1: what it is. That's kind of stuff. It's like a

910
00:45:32,560 --> 00:45:36,920
Speaker 1: fixed background, we call it. But in general relativity, space

911
00:45:36,960 --> 00:45:40,320
Speaker 1: time is dynamical. It's not like fixed can bend and twist,

912
00:45:40,320 --> 00:45:44,160
Speaker 1: and it doesn't like exist inside some other kind of space.

913
00:45:44,520 --> 00:45:47,080
Speaker 1: We have this way to like calculate the relative distance

914
00:45:47,120 --> 00:45:51,319
Speaker 1: between points, but space itself is not like some new

915
00:45:51,400 --> 00:45:54,520
Speaker 1: field that's sitting inside some sort of meta space or

916
00:45:54,560 --> 00:45:58,799
Speaker 1: superspace or subspace or some other kind of space. It

917
00:45:58,880 --> 00:46:01,520
Speaker 1: tells us that this like there is no fixed background.

918
00:46:01,960 --> 00:46:06,800
Speaker 1: So people describe general relativity as background independent, like the universe.

919
00:46:06,840 --> 00:46:10,960
Speaker 1: Space itself is not sitting inside some sort of deeper box,

920
00:46:11,600 --> 00:46:13,200
Speaker 1: and which is kind of weird because it makes you

921
00:46:13,239 --> 00:46:16,520
Speaker 1: feel a little like unmoored from the foundations of reality.

922
00:46:17,400 --> 00:46:21,120
Speaker 6: But I guess maybe couldn't you just have quantum mechanics

923
00:46:21,160 --> 00:46:24,360
Speaker 6: sit on top of a bendy stretch, Hey, space time.

924
00:46:25,160 --> 00:46:27,680
Speaker 6: You know, sort of like you know, the planet Earth

925
00:46:27,719 --> 00:46:30,319
Speaker 6: of the Sun are moving through space time and they're

926
00:46:30,320 --> 00:46:33,800
Speaker 6: getting they're flowing through the curvature and all the bending.

927
00:46:34,280 --> 00:46:37,719
Speaker 6: Couldn't you have quantum fields also kind of right on

928
00:46:37,800 --> 00:46:39,600
Speaker 6: top of the curves of space time.

929
00:46:39,719 --> 00:46:41,880
Speaker 1: M hmm. And I love how you just like casually

930
00:46:41,960 --> 00:46:47,040
Speaker 1: suggesting these solutions, which are like whole areas of research work.

931
00:46:49,560 --> 00:46:52,880
Speaker 6: Daniel Kan, I mean, I just spent five twenty minutes

932
00:46:52,920 --> 00:46:54,799
Speaker 6: talking about this, and I already know how to come

933
00:46:54,880 --> 00:46:57,839
Speaker 6: up with the answer basically, so long.

934
00:46:58,440 --> 00:47:00,120
Speaker 1: No, I don't mean to marck it at all. I

935
00:47:00,120 --> 00:47:02,520
Speaker 1: mean that these are actually really clever ways forward, and

936
00:47:02,560 --> 00:47:04,920
Speaker 1: these are exactly the things that people are working on

937
00:47:05,320 --> 00:47:08,200
Speaker 1: at the cutting edge. It turns out to be complicated.

938
00:47:08,320 --> 00:47:11,640
Speaker 1: You can do quantum mechanics on curved space You can

939
00:47:11,719 --> 00:47:15,880
Speaker 1: put these fields on curved space time, and mostly it

940
00:47:15,960 --> 00:47:19,319
Speaker 1: works as long as the curvature is small, so like

941
00:47:19,360 --> 00:47:22,000
Speaker 1: if they're a little bit curved, things are fine. As

942
00:47:22,040 --> 00:47:24,440
Speaker 1: soon as the curvature becomes large, you get back to

943
00:47:24,440 --> 00:47:27,239
Speaker 1: all those crazy infinities that we can't wrangle in all

944
00:47:27,239 --> 00:47:31,440
Speaker 1: sorts of nonsense predictions. So the quantum mechanical theory breaks

945
00:47:31,520 --> 00:47:34,360
Speaker 1: down if the curvature is really really high. So we

946
00:47:34,440 --> 00:47:36,560
Speaker 1: just don't know how to do those kinds of calculations.

947
00:47:38,440 --> 00:47:41,560
Speaker 6: And that includes time, right because like in general relativity,

948
00:47:41,960 --> 00:47:44,680
Speaker 6: time can slow down and time can speed up. And

949
00:47:44,719 --> 00:47:45,920
Speaker 6: so you're saying you don't know how to do that

950
00:47:45,960 --> 00:47:47,480
Speaker 6: at quantum mechanics exactly.

951
00:47:47,480 --> 00:47:49,479
Speaker 1: We don't know how to do that in quantum mechanics. Again,

952
00:47:49,560 --> 00:47:51,880
Speaker 1: when the curvature is high, for what they call a

953
00:47:51,920 --> 00:47:55,680
Speaker 1: weak field gravity, where it's like a very small effect gravity,

954
00:47:55,920 --> 00:47:58,600
Speaker 1: then we can do those calculations and and even feel

955
00:47:58,640 --> 00:48:02,200
Speaker 1: the influence of gravity, not just negligible gravity, just weak gravity.

956
00:48:02,440 --> 00:48:04,879
Speaker 1: But when gravity gets strong, which is what it does

957
00:48:04,920 --> 00:48:07,399
Speaker 1: near a black hole, where we think these two things

958
00:48:07,440 --> 00:48:10,319
Speaker 1: are both important, we don't know how to do those calculations.

959
00:48:10,360 --> 00:48:13,839
Speaker 1: That's when quantum mechanics on Kurve space breaks down because

960
00:48:13,840 --> 00:48:16,400
Speaker 1: of all these infinities we can't grapple with all.

961
00:48:16,480 --> 00:48:20,200
Speaker 6: Right, Well, as we mentioned, we're not quite experts in

962
00:48:20,239 --> 00:48:23,200
Speaker 6: this topic, but we don't Maybe we will talk to

963
00:48:23,280 --> 00:48:25,239
Speaker 6: one of the smartest people in the universe who is

964
00:48:25,600 --> 00:48:27,880
Speaker 6: tackling this problem directly.

965
00:48:27,880 --> 00:48:30,400
Speaker 1: That's right. So I reach down to Nathan, whose father

966
00:48:30,680 --> 00:48:33,120
Speaker 1: is a listener of the podcast and listen to the

967
00:48:33,160 --> 00:48:35,879
Speaker 1: podcast mostly so you can have a hope of understanding

968
00:48:35,920 --> 00:48:39,319
Speaker 1: his son's research. Nathan is a physics bread student at

969
00:48:39,360 --> 00:48:43,239
Speaker 1: Arizona State University, a well known department with experts in

970
00:48:43,280 --> 00:48:46,960
Speaker 1: cosmology and theories of quantum gravity, and he was kind

971
00:48:47,040 --> 00:48:49,200
Speaker 1: enough to spend five minutes talking to me about his

972
00:48:49,239 --> 00:48:50,359
Speaker 1: research and.

973
00:48:50,320 --> 00:48:54,520
Speaker 6: So here at Daniel's interview with Nathan Berwig, quantum gravity researcher.

974
00:48:55,280 --> 00:48:58,800
Speaker 1: So then it's my pleasure to welcome Nathan to the podcast. Nathan,

975
00:48:58,960 --> 00:49:01,839
Speaker 1: please introduce yourself and tell the listeners who you are.

976
00:49:02,600 --> 00:49:07,160
Speaker 4: Yes, So, I'm Nathan Berwick. I'm currently a first year

977
00:49:07,280 --> 00:49:13,680
Speaker 4: PhD student at Arizona State University studying physics and cosmology

978
00:49:14,840 --> 00:49:19,440
Speaker 4: and hoping to continue doing so and move into ideally

979
00:49:19,680 --> 00:49:21,480
Speaker 4: stuff along the lines of quantum gravity.

980
00:49:21,600 --> 00:49:24,759
Speaker 1: Awesome. Well, we often talk on the podcast about how

981
00:49:24,880 --> 00:49:27,719
Speaker 1: science is just a bunch of people following their curiosity

982
00:49:27,840 --> 00:49:30,880
Speaker 1: and pushing forward the forefront of knowledge. So tell us

983
00:49:30,920 --> 00:49:34,319
Speaker 1: what is it about physics and gr that drew you in,

984
00:49:34,360 --> 00:49:36,840
Speaker 1: that made you decide you want to spend your life

985
00:49:37,000 --> 00:49:38,040
Speaker 1: on this question.

986
00:49:38,840 --> 00:49:42,279
Speaker 4: That's a really good question. So I think part of

987
00:49:42,320 --> 00:49:44,160
Speaker 4: it is just I always kind of grew up as

988
00:49:44,239 --> 00:49:47,760
Speaker 4: a curious kid, and you know, when I was younger,

989
00:49:47,760 --> 00:49:49,880
Speaker 4: I always knew I wanted to be like a scientist

990
00:49:50,040 --> 00:49:54,799
Speaker 4: in air quotes. But eventually I sort of narrowed in

991
00:49:54,840 --> 00:49:58,640
Speaker 4: on physics. And I think as soon as I learned

992
00:49:58,640 --> 00:50:01,440
Speaker 4: about like the most basic content in general relativity, sort

993
00:50:01,480 --> 00:50:04,560
Speaker 4: of the idea that space time is one great big

994
00:50:04,600 --> 00:50:07,319
Speaker 4: thing and gravity is just the curvature of that, it

995
00:50:07,400 --> 00:50:11,400
Speaker 4: was just immediately alluring, especially when you start to consider

996
00:50:12,360 --> 00:50:15,920
Speaker 4: how gravity is, like are most interacted with force at

997
00:50:16,000 --> 00:50:18,920
Speaker 4: least sort of perceptually. You know, we talk about it

998
00:50:18,960 --> 00:50:22,400
Speaker 4: a lot. You don't really talk about how electromagnet doesn't

999
00:50:22,440 --> 00:50:24,920
Speaker 4: really plays a role in your life very often. But

1000
00:50:25,239 --> 00:50:30,160
Speaker 4: it's also very poorly understood in general, and there's still

1001
00:50:30,200 --> 00:50:33,000
Speaker 4: like a lot of really big open questions to be

1002
00:50:33,080 --> 00:50:36,120
Speaker 4: answered for general relativity, and I think that sort of

1003
00:50:36,200 --> 00:50:40,560
Speaker 4: openness is very much an invitation to explore, which I

1004
00:50:40,600 --> 00:50:41,000
Speaker 4: really like.

1005
00:50:41,200 --> 00:50:42,800
Speaker 1: So you're not going to give your dad any credit

1006
00:50:42,840 --> 00:50:45,120
Speaker 1: for encouraging you to study physics.

1007
00:50:46,080 --> 00:50:49,880
Speaker 4: I think I think I definitely should. Yeah, No, you

1008
00:50:49,920 --> 00:50:54,120
Speaker 4: definitely like fostered my curiosity in physics growing up. Both

1009
00:50:54,160 --> 00:50:56,920
Speaker 4: my parents did. But my dad was always fascinated in physics,

1010
00:50:57,480 --> 00:50:59,920
Speaker 4: and so from just like really small things, you know,

1011
00:51:00,120 --> 00:51:02,879
Speaker 4: we'd always find questions on the internet, you know, whether

1012
00:51:02,920 --> 00:51:04,560
Speaker 4: it be a bad string theory, which is always like

1013
00:51:04,600 --> 00:51:07,319
Speaker 4: a very big, you know, media topic and whatnot. But

1014
00:51:07,440 --> 00:51:10,000
Speaker 4: he definitely played a very big role in me wanting

1015
00:51:10,040 --> 00:51:10,720
Speaker 4: to do physics.

1016
00:51:11,480 --> 00:51:14,080
Speaker 1: So a lot of people say that general relativity, once

1017
00:51:14,080 --> 00:51:17,600
Speaker 1: you fully understand it is deep and beautiful, do you

1018
00:51:17,640 --> 00:51:19,920
Speaker 1: have that kind of esthetic reaction to it?

1019
00:51:20,440 --> 00:51:22,040
Speaker 4: Yeah, I think a lot of the beauty of it

1020
00:51:22,080 --> 00:51:26,480
Speaker 4: comes from the idea alone that it's all just curvature,

1021
00:51:27,360 --> 00:51:30,800
Speaker 4: that gravity is in essence just curvature of this big

1022
00:51:31,280 --> 00:51:33,880
Speaker 4: manifold which you may or may not well, which you

1023
00:51:33,920 --> 00:51:37,239
Speaker 4: can't really visualize. But that, for me is the part

1024
00:51:37,280 --> 00:51:42,080
Speaker 4: of the esthetic that general relativity has is just like

1025
00:51:42,120 --> 00:51:44,320
Speaker 4: a breakdown into a more fundamental concept.

1026
00:51:44,600 --> 00:51:48,080
Speaker 1: So if gr is so gorgeous and it works so well,

1027
00:51:48,160 --> 00:51:51,440
Speaker 1: all these experiments confirming Einstein all the time, how can

1028
00:51:51,440 --> 00:51:53,840
Speaker 1: it be wrong? I mean, is it wrong in the

1029
00:51:53,840 --> 00:51:56,799
Speaker 1: way that like Newton's gravity is wrong where it was

1030
00:51:56,840 --> 00:51:59,840
Speaker 1: telling fundamentally the wrong story about what was happening, but

1031
00:52:00,120 --> 00:52:03,399
Speaker 1: didn't really notice until we dug into the details, or

1032
00:52:03,640 --> 00:52:06,400
Speaker 1: is it mostly telling the right story just needs some

1033
00:52:06,560 --> 00:52:09,000
Speaker 1: like corrections and band aids here and there.

1034
00:52:09,239 --> 00:52:12,040
Speaker 4: Yeah, So that's a really good question, and I think

1035
00:52:12,080 --> 00:52:15,080
Speaker 4: it really depends on how much of the last one

1036
00:52:15,160 --> 00:52:19,479
Speaker 4: hundred years you're willing to disregard. And you know that

1037
00:52:19,480 --> 00:52:22,840
Speaker 4: that has certain consequences but also benefits. But I think

1038
00:52:23,200 --> 00:52:28,400
Speaker 4: the most generally accepted perspective right now is that it

1039
00:52:28,440 --> 00:52:32,960
Speaker 4: needs band aids. Because general relativity, as this idea of

1040
00:52:33,200 --> 00:52:37,440
Speaker 4: gravity being caused by space time curvature, is so so

1041
00:52:37,680 --> 00:52:41,280
Speaker 4: rigorously tested at the moment. You know, we keep trying

1042
00:52:41,280 --> 00:52:45,360
Speaker 4: to knock Einstein down and find errors in his theory somewhere,

1043
00:52:45,600 --> 00:52:50,520
Speaker 4: but every single time like he just was right. And

1044
00:52:50,560 --> 00:52:54,279
Speaker 4: so that's a difficult thing to try and find errors in.

1045
00:52:54,360 --> 00:52:59,000
Speaker 4: But there's obviously still big questions. So quantum gravity is

1046
00:52:59,280 --> 00:53:04,799
Speaker 4: probably the largest area of questions regarding general relativity, and

1047
00:53:05,000 --> 00:53:07,480
Speaker 4: a lot of that has to do with just quantum

1048
00:53:07,480 --> 00:53:10,120
Speaker 4: mechanics not playing nicely when you try and think about

1049
00:53:10,520 --> 00:53:13,239
Speaker 4: how gravitational fields work with it. General relativity doesn't have

1050
00:53:13,239 --> 00:53:18,239
Speaker 4: any fundamental understanding of what probability distribution looks like. There's

1051
00:53:18,239 --> 00:53:22,360
Speaker 4: no like wave function understanding when you start getting into

1052
00:53:22,960 --> 00:53:25,080
Speaker 4: the smaller regimes for general relativity.

1053
00:53:25,560 --> 00:53:28,200
Speaker 1: So that's a really big topic like general relativity and

1054
00:53:28,239 --> 00:53:31,080
Speaker 1: quantum mechanics. What are you actually researching right now? Like,

1055
00:53:31,120 --> 00:53:33,520
Speaker 1: what are you working on today today?

1056
00:53:33,760 --> 00:53:38,480
Speaker 4: So throughout the last semester, I've been working on what

1057
00:53:38,520 --> 00:53:42,400
Speaker 4: are called scalar tensor theories, which I actually think you

1058
00:53:42,440 --> 00:53:45,560
Speaker 4: guys did an episode fairly recently on no hair theorems

1059
00:53:45,600 --> 00:53:49,480
Speaker 4: for black holes, and that's very much what I'm working

1060
00:53:49,520 --> 00:53:53,560
Speaker 4: on at the moment, just showing that there's no sort

1061
00:53:53,560 --> 00:53:57,760
Speaker 4: of scalar hairs for certain types of theories.

1062
00:53:58,000 --> 00:54:02,399
Speaker 1: Cool. So then I'm gonna ask you speculate unscientifically, what

1063
00:54:02,480 --> 00:54:05,000
Speaker 1: do you think is inside a black hole?

1064
00:54:06,560 --> 00:54:06,960
Speaker 4: Oh?

1065
00:54:07,160 --> 00:54:07,440
Speaker 1: Boy?

1066
00:54:07,600 --> 00:54:10,200
Speaker 4: What do I think is inside a black hole? Speculative

1067
00:54:10,200 --> 00:54:12,319
Speaker 4: answer is, well, if it's a big black hole, there's

1068
00:54:12,320 --> 00:54:15,239
Speaker 4: probably stuff sort of floating around in there being eaten up.

1069
00:54:15,320 --> 00:54:19,960
Speaker 4: But I like to think that there's this sort of

1070
00:54:20,000 --> 00:54:25,360
Speaker 4: taboo in physics of natural infinities. They aren't there. Usually

1071
00:54:25,360 --> 00:54:28,960
Speaker 4: when there's an infinity, it's something horribly horribly wrong. And

1072
00:54:29,000 --> 00:54:31,319
Speaker 4: that was sort of the big hub up when they

1073
00:54:31,360 --> 00:54:33,360
Speaker 4: figured out that black holes could be a thing that

1074
00:54:33,440 --> 00:54:37,000
Speaker 4: actually existed, was that it just felt wrong that there

1075
00:54:37,000 --> 00:54:41,000
Speaker 4: could be such a dense object that's just so infinitely packed.

1076
00:54:41,520 --> 00:54:43,799
Speaker 4: I like to think that it is just, you know,

1077
00:54:43,920 --> 00:54:49,879
Speaker 4: a perfectly infinite density singularity, just because I think it'd

1078
00:54:49,920 --> 00:54:53,239
Speaker 4: be very wild and wacky and cool to have this

1079
00:54:53,480 --> 00:54:59,640
Speaker 4: very strange yet natural like divergence or infinity just existing

1080
00:54:59,680 --> 00:55:00,440
Speaker 4: in the universe.

1081
00:55:00,800 --> 00:55:03,480
Speaker 1: Do you think the singularity inside a black hole is

1082
00:55:03,520 --> 00:55:06,799
Speaker 1: as dense as boba? You know, these chewy blobs of

1083
00:55:06,880 --> 00:55:10,560
Speaker 1: death that people inexplicably like shooting up their straws as

1084
00:55:10,600 --> 00:55:13,640
Speaker 1: they enjoy and otherwise relaxing beverage. I happen to know

1085
00:55:13,760 --> 00:55:15,359
Speaker 1: your father agrees with me on this.

1086
00:55:18,280 --> 00:55:21,200
Speaker 4: He sent me a clip of this just the other day. Oh.

1087
00:55:22,920 --> 00:55:26,120
Speaker 4: I certainly hope that boba is it not at all

1088
00:55:26,280 --> 00:55:30,560
Speaker 4: comparable to singularities. But I suppose you never know what

1089
00:55:30,760 --> 00:55:34,000
Speaker 4: that would be the hell that my dad would die on.

1090
00:55:34,120 --> 00:55:36,879
Speaker 1: I think, well, I think maybe your dad should open

1091
00:55:36,960 --> 00:55:40,120
Speaker 1: up a black hole boba shop that sells black hole boba,

1092
00:55:40,400 --> 00:55:45,279
Speaker 1: super dense, super dense little chunks of destruction. All right, Nathan,

1093
00:55:45,320 --> 00:55:47,520
Speaker 1: thanks very much for taking some time to talk to

1094
00:55:47,600 --> 00:55:50,160
Speaker 1: us about your work on the forefront of understanding of

1095
00:55:50,200 --> 00:55:52,879
Speaker 1: John relativity and good luck figuring it all out.

1096
00:55:53,440 --> 00:55:55,000
Speaker 4: Thank you very much, Thank you for having me.

1097
00:55:56,360 --> 00:56:01,040
Speaker 6: All right, interesting chat there, pretty controver vircial about both

1098
00:56:01,080 --> 00:56:02,280
Speaker 6: boba and black holes.

1099
00:56:03,120 --> 00:56:05,560
Speaker 1: You know, this is the cutting edge of food science

1100
00:56:05,680 --> 00:56:06,960
Speaker 1: and quantum gravity.

1101
00:56:07,320 --> 00:56:13,520
Speaker 6: That's right, and sugary drinks. Yes, But it's interesting that

1102
00:56:14,160 --> 00:56:17,000
Speaker 6: he seems to follow pretty strongly on the general latuty side.

1103
00:56:17,040 --> 00:56:19,239
Speaker 6: He thinks inside of black holes are singularities.

1104
00:56:19,360 --> 00:56:22,320
Speaker 1: Yeah. I've seen this in a lot of quantum gravity theorists,

1105
00:56:22,640 --> 00:56:26,680
Speaker 1: that they are intoxicated by the beauty of general relativity.

1106
00:56:27,040 --> 00:56:29,399
Speaker 1: It's sort of hard to overstate the impact this has

1107
00:56:29,400 --> 00:56:32,680
Speaker 1: on people. When they are able to import Einstein's equations

1108
00:56:32,680 --> 00:56:35,319
Speaker 1: into their mind and they can see the universe in

1109
00:56:35,400 --> 00:56:38,560
Speaker 1: terms of this differential manifold, they feel like the scales

1110
00:56:38,600 --> 00:56:40,680
Speaker 1: have fallen from their eyes and they're seeing the universe

1111
00:56:40,719 --> 00:56:42,720
Speaker 1: the way it really is, and it has to be true.

1112
00:56:43,280 --> 00:56:45,920
Speaker 1: So they want to preserve this vision of the universe

1113
00:56:46,120 --> 00:56:50,080
Speaker 1: as having curved space time. It's not exactly religious, but

1114
00:56:50,120 --> 00:56:52,080
Speaker 1: it's almost like a spiritual experience.

1115
00:56:52,280 --> 00:56:55,239
Speaker 6: Oh my goodness. This is coming from, of course, a

1116
00:56:55,320 --> 00:56:59,279
Speaker 6: quantum mechanics particle researcher. Right, you're trying to say that

1117
00:56:59,280 --> 00:57:03,000
Speaker 6: the others a bunch of religious zillo its because your

1118
00:57:03,120 --> 00:57:04,279
Speaker 6: side is obviously right.

1119
00:57:04,360 --> 00:57:06,600
Speaker 1: I mean they like boba, so what so you can't

1120
00:57:06,600 --> 00:57:07,560
Speaker 1: trust them at all?

1121
00:57:09,239 --> 00:57:11,759
Speaker 6: Well, boba are like particles, so I would have thought

1122
00:57:11,760 --> 00:57:13,880
Speaker 6: they're fuzzy particles. I would have value you be a

1123
00:57:13,880 --> 00:57:14,279
Speaker 6: big fan.

1124
00:57:14,400 --> 00:57:16,680
Speaker 1: No, they're macroscopic, man, They're dominated by gravity.

1125
00:57:16,840 --> 00:57:21,280
Speaker 6: Oom. Well, I wonder if maybe there is a singularity,

1126
00:57:21,320 --> 00:57:24,200
Speaker 6: you know, and maybe it's also fuzzy at the center

1127
00:57:24,240 --> 00:57:26,480
Speaker 6: of it. It's just that maybe in a singularity, space

1128
00:57:26,680 --> 00:57:30,880
Speaker 6: is so compressed or so squished together, that maybe the

1129
00:57:31,160 --> 00:57:33,120
Speaker 6: quantum certainties also get squished down.

1130
00:57:33,320 --> 00:57:35,400
Speaker 1: Maybe we're gonna solve quantum gravity right here on this

1131
00:57:35,440 --> 00:57:36,480
Speaker 1: podcast today.

1132
00:57:36,800 --> 00:57:40,240
Speaker 6: Yeah, yeah, let's do it. Why wait a hundred years,

1133
00:57:40,320 --> 00:57:42,840
Speaker 6: let's come up with that romantic comedy sci fi movie

1134
00:57:42,960 --> 00:57:43,320
Speaker 6: right now?

1135
00:57:43,400 --> 00:57:46,560
Speaker 1: Why it's quantum gravity so hard because nobody asked a cartoonist.

1136
00:57:47,080 --> 00:57:53,439
Speaker 6: There you go, boom, question answered, Boom done. Let's let's

1137
00:57:53,480 --> 00:58:00,600
Speaker 6: go tackle something harder like cancer or oba democracy. All right, Well,

1138
00:58:01,200 --> 00:58:03,760
Speaker 6: you're on one side, people like Nathan are on the

1139
00:58:03,760 --> 00:58:05,920
Speaker 6: other side. Sounds like we still have a long way

1140
00:58:05,920 --> 00:58:06,120
Speaker 6: to go.

1141
00:58:06,280 --> 00:58:07,760
Speaker 1: We do have a long way to go, and there

1142
00:58:07,800 --> 00:58:12,240
Speaker 1: are deep philosophical and mathematical hurdles to overcome. We want

1143
00:58:12,360 --> 00:58:14,280
Speaker 1: to have a single theory of the universe, one that

1144
00:58:14,360 --> 00:58:17,240
Speaker 1: gives us a complete picture of what's really happening the

1145
00:58:17,280 --> 00:58:20,720
Speaker 1: source code for the universe. But so far none of

1146
00:58:20,760 --> 00:58:22,800
Speaker 1: our attempts actually compute.

1147
00:58:22,440 --> 00:58:25,200
Speaker 6: And so it's an active area of research, maybe waiting

1148
00:58:25,240 --> 00:58:28,920
Speaker 6: for the next person to tackle this and possibly solve it.

1149
00:58:29,280 --> 00:58:32,040
Speaker 6: And that could be you out there asking these questions,

1150
00:58:32,120 --> 00:58:35,640
Speaker 6: listening to this podcast, wondering how the universe works.

1151
00:58:35,760 --> 00:58:39,200
Speaker 1: I hope that future genius doesn't suffer an unfortunate boba accident,

1152
00:58:39,560 --> 00:58:42,840
Speaker 1: choking to death before they can share their insights with humanity.

1153
00:58:42,960 --> 00:58:46,880
Speaker 6: Oh my gosh, it's a little bit dark there, a

1154
00:58:46,920 --> 00:58:49,520
Speaker 6: little bit dark. I think you need a pretty large

1155
00:58:49,560 --> 00:58:53,760
Speaker 6: bobba ball there to choke on it. It's boba relativity,

1156
00:58:53,960 --> 00:58:56,760
Speaker 6: that's right, The answer, the choking hazard of a boba

1157
00:58:57,280 --> 00:59:00,760
Speaker 6: is there. All right? Well, stay tuned. You hope you

1158
00:59:00,880 --> 00:59:04,320
Speaker 6: enjoyed that. Thanks for joining us. See you next time.

1159
00:59:08,120 --> 00:59:11,360
Speaker 1: For more science and curiosity. Come find us on social media,

1160
00:59:11,440 --> 00:59:15,520
Speaker 1: where we answer questions and post videos. We're on Twitter, Discord,

1161
00:59:15,640 --> 00:59:19,280
Speaker 1: Insta and now TikTok. Thanks for listening and remember that

1162
00:59:19,400 --> 00:59:23,200
Speaker 1: Daniel and Jorge Explain the Universe is a production of iHeartRadio.

1163
00:59:23,520 --> 00:59:28,680
Speaker 1: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,

1164
00:59:28,800 --> 00:59:36,360
Speaker 1: or wherever you listen to your favorite shows. When you

1165
00:59:36,400 --> 00:59:38,440
Speaker 1: pop a piece of cheese into your mouth, you're probably

1166
00:59:38,480 --> 00:59:41,520
Speaker 1: not thinking about the environmental impact. But the people in

1167
00:59:41,560 --> 00:59:44,680
Speaker 1: the dairy industry are. That's why they're working hard every

1168
00:59:44,760 --> 00:59:48,080
Speaker 1: day to find new ways to reduce waste, conserve natural resources,

1169
00:59:48,120 --> 00:59:52,160
Speaker 1: and drive down greenhouse gas emissions. House US dairy tackling

1170
00:59:52,200 --> 00:59:55,960
Speaker 1: greenhouse gases. Many farms use anaerobic digestors to turn the

1171
00:59:56,000 --> 01:00:00,400
Speaker 1: methane from manure into renewable energy that can power farms

1172
01:00:00,440 --> 01:00:03,720
Speaker 1: and electric cars. Visit you as dairy dot COM's Last

1173
01:00:03,720 --> 01:00:05,320
Speaker 1: Sustainability to learn more.

1174
01:00:06,000 --> 01:00:09,640
Speaker 2: We're just days away from our twenty twenty four iHeart

1175
01:00:09,760 --> 01:00:12,640
Speaker 2: Radio Music Festival, preceded by Capital One.

1176
01:00:12,920 --> 01:00:16,120
Speaker 3: The biggest headliners in live music will be taking over

1177
01:00:16,240 --> 01:00:17,960
Speaker 3: to Mobile Arena, Las Vegas.

1178
01:00:18,080 --> 01:00:20,720
Speaker 5: Lost some special surprises of moments you are not going

1179
01:00:20,800 --> 01:00:21,800
Speaker 5: to want to miss.

1180
01:00:21,920 --> 01:00:23,360
Speaker 6: Stream only on Hulu.

1181
01:00:23,400 --> 01:00:27,440
Speaker 5: The Ihart Radio Music Festival and Listen on iHeartRadio the

1182
01:00:27,440 --> 01:00:30,680
Speaker 5: most anticipated live music events of the.

1183
01:00:31,200 --> 01:00:34,800
Speaker 3: Year this Friday and Saturday, starting at ten thirty pm Eastern,

1184
01:00:34,880 --> 01:00:35,960
Speaker 3: seven thirty Pacific.

1185
01:00:36,560 --> 01:00:38,920
Speaker 8: We think of Franklin as the doddling dude flying a

1186
01:00:39,000 --> 01:00:39,640
Speaker 8: kite and no rain.

1187
01:00:39,840 --> 01:00:42,080
Speaker 9: Benjamin Franklin is our subject for a new season with

1188
01:00:42,120 --> 01:00:42,880
Speaker 9: Walter Isaacson.

1189
01:00:43,040 --> 01:00:47,400
Speaker 8: He's the most successful self made business person in America.

1190
01:00:46,880 --> 01:00:49,920
Speaker 9: A printer, a scientist, founding father, but maybe not the

1191
01:00:49,960 --> 01:00:50,680
Speaker 9: guy we think we know.

1192
01:00:50,920 --> 01:00:54,280
Speaker 8: Franklin casts his lot on the side of revolution, and

1193
01:00:54,560 --> 01:00:57,320
Speaker 8: it's another thing that splits the family apart.

1194
01:00:57,760 --> 01:01:01,040
Speaker 9: Listen to on Benjamin Franklin with Walter Isaacson on iHeartRadio, app,

1195
01:01:01,080 --> 01:01:03,400
Speaker 9: Apple Podcasts, or wherever you get your podcasts.