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Speaker 1: Hey, Daniel, how smart do you have to be to

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Speaker 1: be a physicist?

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Speaker 2: You know, it's not actually about being smart. It's more

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Speaker 2: about thinking that these kind of particular challenges are really fun.

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Speaker 1: So if you like having fun, you shouldn't be a physicist.

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Speaker 1: What do you mean?

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Speaker 2: I mean, you know, science is a very personal thing,

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Speaker 2: so some people might think doing integrals is really boring,

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Speaker 2: and somebody else might do them to relax.

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Speaker 1: Well, are you saying math can be relaxing.

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Speaker 2: It can be relaxing, and it can also be exciting.

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Speaker 1: You know.

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Speaker 2: Sometimes you're like bush whacking through the math and you

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Speaker 2: make amazing discoveries and you don't even have to risk

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Speaker 2: your life to jaguars.

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Speaker 1: Well you do have to worry about paper cuts, right.

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Speaker 2: Yeah, you know. I think there's a reason they didn't

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Speaker 2: make Indiana Jones a physicist.

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Speaker 1: Yeah. I don't think physicists could pull off the Indiana

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Speaker 1: Jones hat.

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Speaker 2: And we all have daddy issues.

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Speaker 1: Hi. I'm Jorge make, cartoonist and the author of Oliver's

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Speaker 1: Great Big Universe.

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Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor

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Speaker 2: at UC Irvine, and I always wanted to have physics

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Speaker 2: adventures ooh.

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Speaker 1: Like real adventures, like in your couch, like, oh no,

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Speaker 1: I spilled my coffee.

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Speaker 2: I don't think you have to risk your life and

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Speaker 2: like get into a spaceship or even become an astronaut

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Speaker 2: to have physics adventures. You know, you can explore the

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Speaker 2: universe in your mind, make amazing discoveries, and feel like

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Speaker 2: you are connecting yourself to the universe.

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Speaker 1: I guess technically aren't like real adventures physical adventures. But

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Speaker 1: I guess maybe you don't want physical adventures, want physics adventures.

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Speaker 2: Yeah, exactly, physics versus.

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Speaker 1: Physical phone You don't want to make any physical exertions

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Speaker 1: or efforts, just like the mental kind.

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Speaker 2: Yeah, but you know, sometimes thinking really hard can make sweat.

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Speaker 2: I've definitely perspired while doing intergrals before.

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Speaker 1: M I see, have you ever wiped out doing integrals?

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Speaker 2: I've never injured myself doing math, that's for sure.

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Speaker 1: Well, I guess some people headaches. I guess that's sort

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Speaker 1: of cow injury.

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Speaker 2: Exactly. Migraines are a hazard of doing physics.

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Speaker 1: Yeah, no, I find math very relaxing, actually puts me

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Speaker 1: right to sleep. In fact, you should make an a

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Speaker 1: f for like a sleep relaxation app. And now we're

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Speaker 1: going to do integrals people do like the all time.

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Speaker 1: There you go, that's very ASMR and you will be

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Speaker 1: subliminally learning math.

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Speaker 2: The billion dollar idea right here.

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Speaker 1: Yeah, I can finally quit this podcast job. But anyways,

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

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Speaker 1: a production of iHeartRadio.

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Speaker 2: In which we do our best to make the complexities

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Speaker 2: and the challenges of physics accessible to you and to everybody,

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Speaker 2: because we think that the whole point of physics is

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Speaker 2: to understand the universe, and not just by a select

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Speaker 2: few group of people who can understand nineteen dimensional string

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Speaker 2: theory integrals, but by everybody. Because the end science is

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Speaker 2: a bunch of stories, mathematical or intuitive or in English,

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Speaker 2: and we want to tell those stories to you.

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Speaker 1: That's right. We take you through the adventures of science,

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Speaker 1: the wipeouts, the close calls, and the headaches of trying

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Speaker 1: to find out how the universe works and what are

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Speaker 1: place in it is.

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Speaker 2: Sometimes these integrals are more annoying than mosquito bites, though

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Speaker 2: never as dangerous as jaguars.

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Speaker 1: I don't think anything is this annoying is mosquitobiites. Jaguars

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Speaker 1: are pretty pesky too. Have you ever seen a jaguar

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Speaker 1: in the wild in the wild? Uh no, no, thankfully not.

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Speaker 1: Or do you mean like a car the car? I

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Speaker 1: think plenty of jaguars around here in South Pasady.

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Speaker 2: That's true, and those drivers can be pretty dangerous.

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Speaker 1: Yeah, yeah, and annoying like mosquitos.

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Speaker 2: You just want to swat all the jaguar drivers.

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Speaker 1: No, no, that's a you can get arrested for that

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Speaker 1: kind of thing. Yeah, exactly, Well, let me insult them

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Speaker 1: on a podcast.

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Speaker 2: When you make a billion dollars on your sleep math

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Speaker 2: app that you can buy yourself a jaguar and you

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Speaker 2: can be the same one.

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Speaker 1: I can buy several jaguars and a mosquito repellent.

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Speaker 2: Well, I was just wondering, because I know you grew

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Speaker 2: up in Panama, if you'd ever seen a jaguar or

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Speaker 2: maybe just jaguar sized mosquitoes.

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Speaker 1: Oh, I see, I see. That's your your perception of

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Speaker 1: how I grew up. I grew up in the hut,

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Speaker 1: in the jungle, barefoot, with my little pet jaguar next

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Speaker 1: to me. Exactly. I think people will live.

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Speaker 2: No, I'm asking paint us the picture.

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Speaker 1: I've seen a lot of coyotes around here in the wild. Yes, yeah,

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Speaker 1: those are pretty dangerous too. I guess if you're the

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Speaker 1: if you're small, you're a small baby or something.

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Speaker 2: In our neighborhood, everybody with a small dog puts these

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Speaker 2: spiky vests on them so the coyotes can't just snatch

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Speaker 2: them up and have a snack.

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Speaker 1: Wait, what you turn your dog into a weapon? What

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Speaker 1: do you mean is like spy? How dangerous are these spikes?

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Speaker 2: They're pretty big because there's a whole epidemic of coyotes

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Speaker 2: jumping into people's backyards and like grabbing these little dogs.

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Speaker 1: Oh wow, maybe just not keep your dog out at night.

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Speaker 1: Don't turn it into dangerous weapon. Like what if the

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Speaker 1: dog runs at a little kid or something wearing this

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Speaker 1: killer jacket.

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Speaker 2: Yeah, these coyotes are pretty brazen. It's not just that night.

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Speaker 2: During the full daylight, they will hop in people's backyards

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Speaker 2: and make off with their little shit.

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Speaker 1: Sues M. Sounds like me. You just just make the

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Speaker 1: coyotes your pets, and then that's also the problem, doesn't it. Well, last,

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Speaker 1: then you get a problem of jaguars coming in here

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Speaker 1: and eating your coyotes.

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Speaker 2: And somehow we have to connect all of this back

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Speaker 2: to physics.

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Speaker 1: Yeah, no, there's a physics zero of sizes right right, yes, sizes. Yes.

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Speaker 2: Some problems are hard, like how to protect your little

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Speaker 2: pet from neighborhood coyotes, and other problems are hard, like

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Speaker 2: how do you figure out the mathematics of the universe?

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Speaker 1: It's all connected, yeah, because I guess. Figuring out the

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Speaker 1: math of the universe has been one of the goals

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Speaker 1: of physics, to understand what's underlying everything that we see

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Speaker 1: around us, and all of the mechanics and the motion

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Speaker 1: and the energy that is swirling around us, what is

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Speaker 1: at the core of the universe.

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Speaker 2: Physics has two great theories, two incredible ideas that have

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Speaker 2: been very very successful, quantum mechanics and general relativity. But

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Speaker 2: bringing them together into an idea of quantum gravity has

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Speaker 2: been a challenge that has stood for over a century.

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Speaker 2: The greatest minds in physics have tried to take a

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Speaker 2: bite out of it, but it seems to be protected

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Speaker 2: by a spiky vest that's right.

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Speaker 1: It's been one of the hardest problems to solve in

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Speaker 1: physics for the last one hundred years, which makes you

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Speaker 1: wonder why is it so hard? What's taking so long

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Speaker 1: to solve this fundamental problem in physics.

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Speaker 2: It's because us physicists haven't just gotten off our couch

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Speaker 2: and bush whacked our way into the mathematical jungle.

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Speaker 1: Yeah. Yeah, I think that's the problem, Daniel. You need

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Speaker 1: to get off your couch an experiment with real gravity,

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Speaker 1: not just like imaginary gravity.

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Speaker 2: I'm waiting for my Indiana Jones hat to come. You

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Speaker 2: can't do it without the right cand of hat. You

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Speaker 2: have to be prepared.

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Speaker 1: Oh that's right, Yeah, that's right. You don't want to

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Speaker 1: get sunburned. It's not like there are other ways to

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Speaker 1: protect yourselves from the UV rays.

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Speaker 2: I mean, I want to understand the universe, but I'm

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Speaker 2: not willing to make physical sacrifices.

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Speaker 1: Do you also need a whip? Also?

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Speaker 2: I want to whip those integrals into shape for sure.

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Speaker 1: Yeah, there you go, crack them into shape. But anyway,

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Speaker 1: to be on the podcast, we'll be tackling the question

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Speaker 1: why is quantum gravity so hard?

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Speaker 3: Now?

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Speaker 1: Is this like hard like difficult or hard like tough?

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Speaker 2: If your floors are made of quantum gravity and you

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Speaker 2: drop your glass, man, is it gonna shatter? Yeah?

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Speaker 1: But how is it going to fall without gravity? Quantum mechanics,

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Speaker 1: I answered everything, it's gonna fall and not fall. No.

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Speaker 2: I love that physics has a name for this theory

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Speaker 2: quantum gravity, but it's just kind of like a placeholder.

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Speaker 2: We don't know what it is, or how it works,

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Speaker 2: or what the mathematics of it are. People argue about

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Speaker 2: different approaches. We already have a name for it, but

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Speaker 2: we haven't even figured it out yet.

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Speaker 1: Sounds unbrand for how physicists name thinks. Well, anyways, we're wondering,

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Speaker 1: as usual, how many people out there had thought about

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Speaker 1: this question of why quantum gravity is so hard? As usual,

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Speaker 1: Daniel went out there and God answers from real people.

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Speaker 2: Thank you to all the real people and definitely not

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Speaker 2: made up had GPT inspired bots who answered this question.

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Speaker 2: If you are a real person and you'd like to

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Speaker 2: answer future questions, please write to me two questions at

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Speaker 2: Danielandjorge dot com.

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Speaker 1: So think about it for a second. Why do you

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Speaker 1: think quantum gravity is so hard to solve? Here's what

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Speaker 1: people had to say.

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Speaker 3: I know that.

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Speaker 4: Quantic mechanic is very good explaining things that happen in

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Speaker 4: very smallst scale, and gravity is not very strong and

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Speaker 4: small as scale.

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Speaker 1: I don't know.

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Speaker 4: I think that's the reason, but I don't really I

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Speaker 4: don't really know.

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Speaker 1: I honestly don't have an intelligent answer for that. But

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Speaker 1: I will say this, if Albert Einstein was afraid of it,

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Speaker 1: that I am too.

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Speaker 4: It's hard because we are trying to apply our comparatively

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Speaker 4: super massive vantage point to these tiny particles in the

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Speaker 4: quantum realm that probably don't even know the difference.

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Speaker 2: They probably don't even know that gravity is a force.

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Speaker 2: Did you mean real people as opposed to chat GPT

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Speaker 2: or real people as opposed to physicists. I'm just now

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Speaker 2: realizing that was a jab.

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Speaker 1: I mean, like not paid actors. Okay, although maybe you

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Speaker 1: should include a chatgypt answer every every time we do this. Interesting. Yeah,

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Speaker 1: that's right now. What does chat GPT say about quantum

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Speaker 1: gravity being so hard?

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Speaker 2: Chatchipt says quantum gravity is consider challenging because it involves

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Speaker 2: the attempt to reconcile two fundamental theories of physics, quantum

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Speaker 2: mechanics and general relativity. Each of these has been incredibly

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Speaker 2: successful in its own but it becomes problematic when combined.

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Speaker 1: Whoa it just did the podcast for us? Done? AI

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Speaker 1: did replace? In our job? Does a chat GPT have

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Speaker 1: like a like a voice out. Can you have it

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Speaker 1: read the answer?

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Speaker 2: I think the free version that I have access to

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Speaker 2: you can't do images or voices. So no, you cannot

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Speaker 2: be replaced by chat jipt just yet.

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Speaker 1: Oh right, you still need us to read the answer

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Speaker 1: chat GPT gives out. I see.

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Speaker 2: Also, I would never rely on chat CHEPT. I asked

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Speaker 2: some hard physics questions sometimes and it just makes up balogney. Oh.

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Speaker 1: I think the news here is that you're asking chat

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Speaker 1: GPT for answers.

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Speaker 2: Yeah, I like everybody else, I was curious when it

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Speaker 2: came out, what you like to talk to the average

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Speaker 2: of the internet wisdom and follies, And the answer is

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Speaker 2: it's not very reliable.

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Speaker 1: Well, technically, neither are we, Daniel. I don't think we're

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Speaker 1: gonna have a hard answer here today.

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Speaker 2: No, but we're not going to make stuff up.

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Speaker 1: Well, So let's dig into this question. Why is quantum

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Speaker 1: gravity so hard? Why is it so difficult? Why has

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Speaker 1: it puzzled physicists for over one hundred years? So let's

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Speaker 1: start with the basics, Daniel, what is quantum gravity?

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Speaker 2: So chatchapt got this bit right. Quant gravity is an

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Speaker 2: attempt to bring together are two great theories of physics.

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Speaker 2: Quantum mechanics that describes things like electromagnetism and how particles

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Speaker 2: work and gives us a probabilistic picture of the universe,

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Speaker 2: and general relativity that described space and time and gravity

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Speaker 2: and explains things like the expansion of the universe and

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Speaker 2: how things move through space and time. And both of

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Speaker 2: these work really really well in their own regime. Quantum

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Speaker 2: mechanics for the small stuff, general relativity for the big stuff.

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Speaker 2: Quantum gravity is an attempt to have a single consistent

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Speaker 2: theory that works for all the stuff.

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Speaker 1: And these were developed independently, sort of right like, while

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Speaker 1: Einstein was coming up with general relativity, other people were

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Speaker 1: thinking about things at the smallest level and why they

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Speaker 1: were it quantized right exactly.

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Speaker 2: They were developed independently, though, around the same time, and

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Speaker 2: both were actually sparked by Einstein. Quantum mechanics really got

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Speaker 2: its kickoff from Einstein's realism that the photoelectric effect, what

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Speaker 2: happens when you shine a bright light at a piece

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Speaker 2: of metal, can only be explained by the fact that

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Speaker 2: photons were little packets. They were quantized. They weren't just

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Speaker 2: continuous beams of energy because what you saw was as

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Speaker 2: you turned up the energy of that beam of light,

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Speaker 2: you didn't get electrons with more energy boiling off. You

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Speaker 2: got more electrons because each one just gets one servant,

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Speaker 2: one photon. That was explained by saying the beam of

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Speaker 2: light had more photons in it, not just a brighter beam.

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Speaker 2: So Einstein kicked off quantum mechanics around the turn of

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Speaker 2: the century, and at the same time he developed his

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Speaker 2: theory of special relativity and general relativity that explained the

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Speaker 2: apparent force of gravity. And these two have been in

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Speaker 2: parallel development over the last hundred years, but nobody's been

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Speaker 2: able to bring them together into one picture of how

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Speaker 2: the universe works.

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Speaker 1: I guess maybe the question is why do you want

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Speaker 1: to bring them together? Like, if you have one that

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Speaker 1: works really well for some things and the other one

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Speaker 1: works well for other things, what's the need to unify them?

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Speaker 2: Yeah, it's a fair question.

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Speaker 1: You know.

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Speaker 2: Sometimes in life we have things that are separate, Like

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Speaker 2: you got one group of friends and another group of friends,

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Speaker 2: you bring them together, it's awkward. You don't do it again, right, Yeah,

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Speaker 2: they're usually a bad idea, And I guess in this

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Speaker 2: case there are two answers. One is philosophical and the

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Speaker 2: other really is experimental. Philosophically, we just think that the

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Speaker 2: universe probably does have a single set of laws. You know,

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Speaker 2: there should be one explanation for why something happens. You know,

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Speaker 2: the same way like when a computer program runs, it's

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Speaker 2: running with one source code. It's not like there's two

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Speaker 2: codes there battling it out. There should be one explanation.

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Speaker 2: And this is just sort of like a philosophical preference.

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Speaker 2: It would be nice if the universe had a single,

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Speaker 2: unified theory. It would sort of make sense to our brains.

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Speaker 2: That doesn't mean it has to happen. It's just sort

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Speaker 2: of like a philosophical preference.

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Speaker 1: Well, maybe explain to folks how they're separate. So, for example,

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Speaker 1: quantum mechanics works to describe what exactly, like the motion

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Speaker 1: or of little tiny particles or their interactions, or what

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Speaker 1: exactly does quantum mechanics do.

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Speaker 2: Quantum mechanics describes everything about tiny little particles, their motion,

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Speaker 2: their interactions, what's going to happen, what's not going to happen.

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Speaker 2: If you have, for example, two electrons and they're interacting

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Speaker 2: with each other, quantum mechanics tells you what's going to happen.

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Speaker 2: You make two electron beams, you shoot them at each other.

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Speaker 2: Quantum mechanics tells you the probabilities of what will come

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Speaker 2: out of those collisions, or if you replace an electron

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Speaker 2: with a muon, or you put in a quark or

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Speaker 2: a proton or whatever. Quantum mechanics is the rules of

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Speaker 2: all of those interactions, and the standard model of particle

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Speaker 2: physics what we talk about on this podcast all the

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Speaker 2: time that has been super successful in explaining the structure

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Speaker 2: of matter deep down inside the atom and why everything's

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Speaker 2: bound together and how that all works. That's all quantum mechanics.

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Speaker 2: It's all fundamentally quantum mechanics. Every little bit of it

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Speaker 2: is quantum mechanical, and it's quantum mechanical because it paints

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Speaker 2: this picture of how the universe works that's very different

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Speaker 2: from the way that our universe seems to work, the

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Speaker 2: one on our level you know about baseballs and planets

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Speaker 2: and basketballs, where things have like smooth paths. It tells

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Speaker 2: us that fundamentally the universe follows very different rules. That

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Speaker 2: quantum objects, tiny little bits, only have probabilities to go places.

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Speaker 2: They don't have smooth.

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Speaker 1: Paths, right, thinks are kind of fuzzy down at the

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Speaker 1: microscopic level. What does general relativity do exactly?

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Speaker 2: So general relativity explains space and time and gravity, So

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Speaker 2: it says that what Newton described as a force of

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Speaker 2: gravity is actually just objects moving through curved space. Newton

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Speaker 2: imagined space was absolute as this backdrop of the universe,

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Speaker 2: and then things with mass had a force between them.

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Speaker 1: You know.

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Speaker 2: He famously explained that apple dropping and also the Moon

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Speaker 2: orbiting the Earth unified in his law of gravity as

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Speaker 2: an attraction between mass. But Einstein tells us that that's

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Speaker 2: not the case. General relativity tells us that actually things

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Speaker 2: are just moving through the curvature of space. Space itself

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Speaker 2: is curved when mass is nearby, and that changes the

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Speaker 2: natural inertial path of objects. Objects will move in what

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Speaker 2: looks like curves even without accelerating.

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Speaker 1: And space gets spent by gravity, right or gravity is

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Speaker 1: the bending of space.

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Speaker 2: Right, base gets spent by energy in a very complex way. Essentially,

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Speaker 2: mass is a kind of energy, so it helps bend space,

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Speaker 2: but it's not the only way you can bend space.

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Speaker 2: And gravity is sort of a fuzzy term. Now, it's like,

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Speaker 2: are you referring to the Newtonian force, which isn't really

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Speaker 2: part of our picture anymore, or you're talking about the

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Speaker 2: whole theory of general relativity as an explanation for it.

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Speaker 2: But you know, what we describe as gravity things seeming

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Speaker 2: to fall down, is explained by Einstein, is things just

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Speaker 2: following the curvature of space.

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Speaker 1: Which which gets a curved because of the presence of energy. Right,

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Speaker 1: that's the basic and that effect. Basically you can sort

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Speaker 1: of lump it into the idea of gravity.

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Speaker 2: Yeah, exactly. And we had a whole podcast digging deep

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Speaker 2: into like why gravity isn't the force and how if

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Speaker 2: you're moving along with the curture of space time you

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Speaker 2: don't feel any acceleration even if other people see you,

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Speaker 2: like moving in circles or moving towards the center of

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Speaker 2: the Earth, all that kind of stuff. It's a really

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Speaker 2: fascinating different way to think about how the universe works.

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Speaker 2: It tells a very different story from Newton's, but it

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Speaker 2: mostly describes really really big stuff because you need a

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Speaker 2: lot of mass to curve space, and that curvature is

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Speaker 2: kind of gentle, so the effect of that curvature is

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Speaker 2: hard to measure, especially compared to these quantum forces, which

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Speaker 2: are extraordinarily powerful in comparison.

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Speaker 1: All right, so now maybe paint us a picture of

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Speaker 1: how they are not unified, Like can I just have

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Speaker 1: some quantum particles interacting in a gravitational field? Or can

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Speaker 1: I just have the path of a quantum particle bent

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Speaker 1: by the bending of space and time. What doesn't these

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Speaker 1: two things do together? Like, what are scenarios in which

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Speaker 1: they exclude each other?

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Speaker 2: Yeah? Great, And so this is sort of like number

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Speaker 2: two reason why we want to unify them, because in

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Speaker 2: some situations they disc Like we talked earlier about having

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Speaker 2: separate theories of the universe, Maybe that's cool, but it's

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Speaker 2: not cool if they're talking about the same phenomenon. If

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Speaker 2: you're asking them the question what happens here? Most of

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Speaker 2: the time you can keep them separate because for tiny,

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Speaker 2: little particles you can ignore gravity. Gravity is very very

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Speaker 2: weak for little particles, and for really big stuff, quantum

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Speaker 2: effects mostly average out. You don't need to know quantum

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Speaker 2: mechanics to predict the path of a baseball. But in

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Speaker 2: some scenarios they do disagree, things like what happens inside

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Speaker 2: a black hole. That's a scenario where you have really

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Speaker 2: powerful gravity so gravity can no longer be ignored. And

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Speaker 2: things are very very small because we think that things

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Speaker 2: are super compressed inside a black hole, so quantum effects

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Speaker 2: are important. So super duper massive, very very tiny objects,

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Speaker 2: quantum mechanics and general relativity disagree about what happens there,

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Speaker 2: and so the universe can't have a contradiction. Two theories

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Speaker 2: tell different stories. They can't both be right.

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Speaker 1: But I guess I mean, in like an everyday scenario,

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Speaker 1: do they work together? Sort of like a man imagining

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Speaker 1: say a microscopic particle, like an electron out there in

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Speaker 1: the near Earth orbit and it's floating out there in

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Speaker 1: space close to the Earth. Does it get pulled by gravity?

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Speaker 1: Is it going to fall down to Earth? Is there

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Speaker 1: a problem with me trying to use quantum mechanics to

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Speaker 1: model how it falls to Earth?

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Speaker 2: Yeah, so you might think, can't we just test quantum

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Speaker 2: gravity and figure out what the answer is, which one's

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Speaker 2: right by looking at the gravity of a tiny quantum particle, Right,

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Speaker 2: So that's what you're asking. What happens for the Earth's

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Speaker 2: gravity on an electron?

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Speaker 1: Yeah? Like, do the two theories break down or do

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Speaker 1: they agree on their normal conditions that are not inside

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Speaker 1: of a black hole.

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Speaker 2: So the two do not agree about what happens to

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Speaker 2: an electron in the Earth's gravitational field.

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Speaker 1: They don't.

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Speaker 2: They don't, but they're not both relevant at the same time.

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Speaker 2: It's a little tricky, and the issue is how do

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Speaker 2: you calculate the gravitational field of the electron, or even

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Speaker 2: the gravitational force on the electron, or the effective curve

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Speaker 2: space however you want to say it, because that depends

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Speaker 2: on where the electron is. Electron is a little quantum

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Speaker 2: particle with quantum effects. Then maybe it has like a

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Speaker 2: fifty percent chance to be at this altitude and fifty

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Speaker 2: percent chance to be at that altitude, in which case

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Speaker 2: it would feel different amounts of gravity. And so how

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Speaker 2: do you calculate the gravity on a quantum particle, We

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Speaker 2: don't know. The theory of quantum gravity would tell us

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Speaker 2: how to do that, but general relativity doesn't tell us

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Speaker 2: how to do that. General relativity requires that you know

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Speaker 2: where the electron is, and so it ignores its quantum nature.

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Speaker 2: So if the quantum nature of the electron is important,

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Speaker 2: it's doing quantumy stuff, then we don't know how to

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Speaker 2: calculate the force of gravity.

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Speaker 3: On it.

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Speaker 2: But also we can't measure the force of gravity on

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Speaker 2: a tiny little object because the force is so small

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Speaker 2: because its mass is so small.

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Speaker 1: Sounds like a great situation and maybe one that we

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Speaker 1: need a little bit more time on. So let's dig

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Speaker 1: into that scenario and dig into well, how exactly these

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Speaker 1: two theories don't match up, and then we'll get into

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Speaker 1: a little bit of the math that makes it so

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Speaker 1: hard to integrate the tube. So let's do that. But

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Speaker 1: first let's take a quick break. All right, we're talking

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Speaker 1: about why quantum gravity theory that unites quantum mechanics and

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Speaker 1: general relativity it's so hard to come up with and

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Speaker 1: to make these two theories play well together. And so Daniel,

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Speaker 1: we're talking about a scenario in which I have an

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Speaker 1: electron in near Earth orbit. It's out there in space

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Speaker 1: above the atmosphere, and I'm trying to figure out what's

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Speaker 1: going to happen to this electron. Is it going to

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Speaker 1: fall to Earth? What path is it going to take

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Speaker 1: as it falls to Earth? And you're saying that it's

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Speaker 1: hard to theoretically predict what's going to happen, right, because

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Speaker 1: it's definitely going to fall if I put an electron

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Speaker 1: on your Earth, right, like it's going to do something,

442
00:22:54,560 --> 00:22:56,399
Speaker 1: but we don't really have a good theory to predict

443
00:22:56,440 --> 00:22:57,080
Speaker 1: what it's going to do.

444
00:22:57,160 --> 00:22:59,280
Speaker 2: Is that what you're saying, we can't be very very

445
00:22:59,280 --> 00:23:02,640
Speaker 2: precise about its predictions. We can be approximate. Like, there's

446
00:23:02,640 --> 00:23:04,959
Speaker 2: two approaches you can take. You can say, I'm going

447
00:23:05,000 --> 00:23:06,879
Speaker 2: to ignore the quantum mechanical part of it. I'm just

448
00:23:06,920 --> 00:23:09,440
Speaker 2: going to treat the electron like it's a tiny little

449
00:23:09,520 --> 00:23:12,320
Speaker 2: rock or a tiny little ball. I'm going to calculate

450
00:23:12,320 --> 00:23:15,000
Speaker 2: its gravity and I think about how it's basically in

451
00:23:15,200 --> 00:23:17,600
Speaker 2: orbit around the Earth. And you can do that and

452
00:23:17,640 --> 00:23:20,640
Speaker 2: you get very good predictions, and you can calculate how

453
00:23:20,640 --> 00:23:22,920
Speaker 2: things boil off the top of the atmosphere or they

454
00:23:22,960 --> 00:23:25,800
Speaker 2: fall to Earth, or whether they're in stable orbits or not.

455
00:23:25,880 --> 00:23:29,200
Speaker 2: So basically, ignore the quantum nature of the electron, treat

456
00:23:29,200 --> 00:23:32,479
Speaker 2: it like a tiny classical object and do gravity on it.

457
00:23:32,720 --> 00:23:33,520
Speaker 2: That's one approach.

458
00:23:33,640 --> 00:23:36,440
Speaker 1: But then you're saying it's hard to know how much

459
00:23:36,440 --> 00:23:40,159
Speaker 1: gravity is applied to the electron because of quantum mechanics,

460
00:23:40,320 --> 00:23:42,800
Speaker 1: or is it hard? Can you just say, like the

461
00:23:42,960 --> 00:23:45,640
Speaker 1: electron has this much mass and it's a little tiny rock,

462
00:23:45,680 --> 00:23:48,000
Speaker 1: and so that's how much gravity's going to feel or

463
00:23:48,119 --> 00:23:49,560
Speaker 1: is that at some level wrong?

464
00:23:49,800 --> 00:23:52,399
Speaker 2: Well, that's at some level wrong because you're ignoring the

465
00:23:52,480 --> 00:23:54,480
Speaker 2: quantum nature of the electron. You're treating it like a

466
00:23:54,520 --> 00:23:56,239
Speaker 2: tiny rock, and it's not a tiny rock.

467
00:23:56,359 --> 00:23:57,919
Speaker 1: Yeah, but I guess. I mean, like, if you do

468
00:23:58,000 --> 00:24:01,000
Speaker 1: treat it like a rock, do you get something wildly

469
00:24:01,080 --> 00:24:03,560
Speaker 1: off or do you get something that seems to be

470
00:24:03,600 --> 00:24:04,440
Speaker 1: pretty exact?

471
00:24:04,720 --> 00:24:06,840
Speaker 2: You get something that works pretty well. As long as

472
00:24:06,840 --> 00:24:09,440
Speaker 2: it doesn't have any interactions. As long as that electron

473
00:24:09,520 --> 00:24:12,639
Speaker 2: is not interacting with any other particles, it's mostly just

474
00:24:12,680 --> 00:24:15,720
Speaker 2: ignoring them, then yeah, you get something that's correct.

475
00:24:15,520 --> 00:24:17,320
Speaker 1: Like it's going to follow the same path as a

476
00:24:17,320 --> 00:24:17,879
Speaker 1: little rock.

477
00:24:18,240 --> 00:24:20,520
Speaker 2: Yes, as long as it's not interacting. But if it's

478
00:24:20,560 --> 00:24:22,879
Speaker 2: in a soup of other electrons and charged particles and

479
00:24:22,920 --> 00:24:26,320
Speaker 2: it's interacting with those, then boom, it's quantum nature becomes

480
00:24:26,400 --> 00:24:31,720
Speaker 2: important and those quantum effects dwarf gravity. They completely take over.

481
00:24:32,320 --> 00:24:34,840
Speaker 2: So you can either ignore the quantum effects and just

482
00:24:34,880 --> 00:24:37,480
Speaker 2: do the gravity, or you can ignore the gravity and

483
00:24:37,680 --> 00:24:41,040
Speaker 2: just do the quantum effects. For an electron, only one

484
00:24:41,080 --> 00:24:43,920
Speaker 2: of those is relevant at a time, and that's why

485
00:24:43,960 --> 00:24:46,679
Speaker 2: you don't need quantum gravity to think about electrons. You

486
00:24:46,680 --> 00:24:50,440
Speaker 2: can do either quantum mechanics or gravity. They're never both

487
00:24:50,560 --> 00:24:51,800
Speaker 2: relevant at the same time.

488
00:24:52,160 --> 00:24:54,359
Speaker 1: But I guess to an approximation. So then when do

489
00:24:54,400 --> 00:24:56,240
Speaker 1: you get into trouble? Like when is it a problem

490
00:24:56,240 --> 00:24:58,760
Speaker 1: that these two are not unified? But what's the scenario?

491
00:24:58,880 --> 00:25:02,000
Speaker 1: Like it's in gravitaational orbit around the Earth, the electron

492
00:25:02,200 --> 00:25:04,600
Speaker 1: is and it's sort of a little bit interacting with

493
00:25:04,640 --> 00:25:06,879
Speaker 1: another electron. Then it's like we don't know what to do.

494
00:25:07,119 --> 00:25:09,639
Speaker 2: As long as it has a quantum interaction, that's just

495
00:25:09,680 --> 00:25:12,720
Speaker 2: going to dominate because the quantum forces are so much

496
00:25:12,760 --> 00:25:16,000
Speaker 2: more powerful than gravity. You know, they're like ten to

497
00:25:16,040 --> 00:25:18,600
Speaker 2: the thirty times as powerful as gravity.

498
00:25:18,920 --> 00:25:21,440
Speaker 1: But like what if it's like ten to thirty one

499
00:25:21,560 --> 00:25:24,720
Speaker 1: times further away, wouldn't it be at the same level

500
00:25:24,720 --> 00:25:25,280
Speaker 1: of gravity.

501
00:25:25,440 --> 00:25:28,640
Speaker 2: I mean gravity falls with distance just like quantum forces do. Right,

502
00:25:28,840 --> 00:25:31,080
Speaker 2: So it's not a matter of distance, it's a matter

503
00:25:31,119 --> 00:25:34,040
Speaker 2: of the mass to charge ratio. Like if you have

504
00:25:34,080 --> 00:25:38,080
Speaker 2: two electrons, they feel a very strong electromagnetic repulsion because

505
00:25:38,080 --> 00:25:41,320
Speaker 2: of their charge. They don't feel a very strong gravitational

506
00:25:41,359 --> 00:25:44,840
Speaker 2: attraction because of their mass. The electromagnetic force there is

507
00:25:44,880 --> 00:25:47,360
Speaker 2: always more powerful at any distance.

508
00:25:47,520 --> 00:25:49,760
Speaker 1: I thought maybe the scenario you're trying to paint was like,

509
00:25:49,760 --> 00:25:52,320
Speaker 1: I have an electron out there in space, and it's

510
00:25:52,320 --> 00:25:55,680
Speaker 1: been attracted by gravity to the giant Earth, but maybe

511
00:25:55,680 --> 00:25:59,040
Speaker 1: it's also sort of being repelled by another electron that's nearby,

512
00:25:59,480 --> 00:26:01,040
Speaker 1: and so then we don't know what's going to happen.

513
00:26:01,320 --> 00:26:03,600
Speaker 2: You have a scenario we have a single electron orbiting

514
00:26:03,640 --> 00:26:06,760
Speaker 2: the Earth, and then some very distant electron is very

515
00:26:06,760 --> 00:26:09,679
Speaker 2: gently pushing on it with the same power as the

516
00:26:09,800 --> 00:26:11,120
Speaker 2: gravity of the entire Earth.

517
00:26:11,400 --> 00:26:14,000
Speaker 1: Yes, Is that like the scenario that you run into

518
00:26:14,000 --> 00:26:15,919
Speaker 1: problems or can you still handle it?

519
00:26:16,400 --> 00:26:19,600
Speaker 2: No, that's a cool idea. That's a scenario where gravity

520
00:26:19,760 --> 00:26:22,439
Speaker 2: and quantum forces are at the same level, and so

521
00:26:22,600 --> 00:26:24,880
Speaker 2: you can't ignore one of them. You have to take

522
00:26:24,920 --> 00:26:27,119
Speaker 2: both into account, and we don't know how to do

523
00:26:27,160 --> 00:26:30,120
Speaker 2: that prediction. That kind of experiment is also pretty hard

524
00:26:30,160 --> 00:26:33,880
Speaker 2: to realize because you need an isolated electron affected by

525
00:26:34,000 --> 00:26:37,760
Speaker 2: only one other electron that's super far away, So it's

526
00:26:37,800 --> 00:26:40,320
Speaker 2: not like practically something we could set up. Otherwise that

527
00:26:40,320 --> 00:26:42,200
Speaker 2: would be really awesome. It would tell us something about

528
00:26:42,280 --> 00:26:43,080
Speaker 2: quantum gravity.

529
00:26:43,160 --> 00:26:45,960
Speaker 1: Yeah, yeah, But that's a physical problem about a physics problem,

530
00:26:46,080 --> 00:26:49,000
Speaker 1: so you know, are couch surfing and Dana Jones doesn't care.

531
00:26:49,080 --> 00:26:50,960
Speaker 2: The other way to tackle this is to say, well,

532
00:26:50,960 --> 00:26:53,640
Speaker 2: what if you have a really really massive quantum particle

533
00:26:53,880 --> 00:26:57,080
Speaker 2: particle that is feeling quantum forces but actually has enough

534
00:26:57,119 --> 00:27:00,440
Speaker 2: mass that it's gravity can't be ignored, and that's when

535
00:27:00,440 --> 00:27:01,000
Speaker 2: you end up at.

536
00:27:00,920 --> 00:27:03,800
Speaker 1: A black hole? All right? So can you be more

537
00:27:03,800 --> 00:27:06,640
Speaker 1: specific about what the problem is, like we don't know

538
00:27:06,680 --> 00:27:09,200
Speaker 1: how to tell what the particle is going to do next,

539
00:27:09,480 --> 00:27:11,439
Speaker 1: or we can't predict how it's going to interact. Can

540
00:27:11,480 --> 00:27:14,520
Speaker 1: you describing words what the problem is at the indecentnarios?

541
00:27:14,680 --> 00:27:17,240
Speaker 2: The problem is that our two theories, general relativity and

542
00:27:17,320 --> 00:27:20,520
Speaker 2: quantum mechanics make different predictions about what's going to happen.

543
00:27:21,200 --> 00:27:23,080
Speaker 1: What do you mean, like one theory says that the

544
00:27:23,119 --> 00:27:24,960
Speaker 1: electron is going to turn right and the other theory

545
00:27:24,960 --> 00:27:26,320
Speaker 1: says the electric is going to turn left.

546
00:27:26,640 --> 00:27:29,240
Speaker 2: Yeah. For example, general relativity is a classical theory, and

547
00:27:29,280 --> 00:27:32,680
Speaker 2: so it assumes electrons have a very definitive location at

548
00:27:32,680 --> 00:27:35,560
Speaker 2: every point in time, whereas quantum mechanics says no, this

549
00:27:35,640 --> 00:27:38,760
Speaker 2: is probabilistic, and you can get things like interference. General

550
00:27:38,800 --> 00:27:41,320
Speaker 2: relativity says, I'm ignoring all that interference stuff, and it's

551
00:27:41,359 --> 00:27:44,040
Speaker 2: going to make a prediction based on treating the electron

552
00:27:44,160 --> 00:27:46,880
Speaker 2: like it's a little rock flying through space. So they're

553
00:27:46,880 --> 00:27:48,880
Speaker 2: going to come up with very different predictions for what's

554
00:27:48,880 --> 00:27:51,840
Speaker 2: going to happen. General relativity doesn't allowed for like entanglement

555
00:27:51,920 --> 00:27:55,320
Speaker 2: or any of the other important quantum effects that totally

556
00:27:55,359 --> 00:27:57,080
Speaker 2: control what happens to an electron.

557
00:27:57,280 --> 00:28:00,639
Speaker 1: I see, because quantum mechanics also might change which direction

558
00:28:00,760 --> 00:28:01,560
Speaker 1: the electron goes.

559
00:28:01,600 --> 00:28:06,040
Speaker 2: Absolutely, yeah, Electromagnetism is a quantum effect, right, Those forces,

560
00:28:06,080 --> 00:28:08,760
Speaker 2: all the forces in the universe that cause acceleration, the

561
00:28:08,760 --> 00:28:12,600
Speaker 2: weak force, electromagnetism, the strong force, These are all quantum effects.

562
00:28:12,600 --> 00:28:16,399
Speaker 2: They all operate on the probabilistic wave functions that control

563
00:28:16,480 --> 00:28:20,440
Speaker 2: these particles. General relativity ignores those. So you ask quantum

564
00:28:20,480 --> 00:28:23,360
Speaker 2: mechanics and gr what's going to happen to this electron.

565
00:28:23,640 --> 00:28:25,439
Speaker 2: They disagree about what's going to happen.

566
00:28:25,960 --> 00:28:27,639
Speaker 1: Well, maybe this is the point where we have to

567
00:28:27,680 --> 00:28:30,280
Speaker 1: get more into the math, because you know, as a

568
00:28:30,320 --> 00:28:32,240
Speaker 1: lad person, I might just say, like, can you just

569
00:28:32,240 --> 00:28:35,320
Speaker 1: add these two things, like why can't just have a

570
00:28:35,400 --> 00:28:39,720
Speaker 1: particle that gravity pulls on its average position, and so

571
00:28:39,840 --> 00:28:43,120
Speaker 1: the average position curves according to gravity, but then where

572
00:28:43,280 --> 00:28:46,000
Speaker 1: it is exactly might be fuzzy due to quantum mechanics.

573
00:28:46,080 --> 00:28:47,840
Speaker 2: Yes, so what you're trying to do right now is

574
00:28:47,880 --> 00:28:49,920
Speaker 2: come up with the theory of quantum gravity. You're trying

575
00:28:49,920 --> 00:28:51,880
Speaker 2: to say, can I get all the good bits of

576
00:28:51,920 --> 00:28:54,760
Speaker 2: general relativity and all the good bits of quantum mechanics

577
00:28:54,760 --> 00:28:57,360
Speaker 2: and smooth them together to make a theory of quantum

578
00:28:57,360 --> 00:29:00,560
Speaker 2: gravity that makes one prediction? Right? And that's the topic

579
00:29:00,560 --> 00:29:03,480
Speaker 2: of the episode. Why is that so hard? And people

580
00:29:03,520 --> 00:29:05,520
Speaker 2: have been working on it for one hundred years. It

581
00:29:05,640 --> 00:29:08,080
Speaker 2: sounds straightforward, but there's a bunch of reasons why it's

582
00:29:08,120 --> 00:29:10,720
Speaker 2: actually quite tricky. One of them is the problem you

583
00:29:10,800 --> 00:29:13,520
Speaker 2: just mentioned, which is this question of like space and

584
00:29:13,600 --> 00:29:18,280
Speaker 2: time and probability. You know, quantum particles don't have definitive locations,

585
00:29:18,760 --> 00:29:22,960
Speaker 2: and general relativity doesn't allow for probabilities in space time.

586
00:29:23,400 --> 00:29:25,640
Speaker 2: What you just described is like, well, what if the

587
00:29:25,680 --> 00:29:28,560
Speaker 2: electron is allowed to have a probability being here or there?

588
00:29:28,640 --> 00:29:31,240
Speaker 2: And so we just say, like space has a probability

589
00:29:31,240 --> 00:29:35,120
Speaker 2: of being curved here and a probability of being curved there. Right,

590
00:29:35,480 --> 00:29:39,120
Speaker 2: that's like a pretty deep change to how general relativity works,

591
00:29:39,360 --> 00:29:42,200
Speaker 2: and the mathematics of it breaks down, Like general relativity

592
00:29:42,200 --> 00:29:44,480
Speaker 2: doesn't allow for those probabilities?

593
00:29:45,040 --> 00:29:47,280
Speaker 1: What do you mean, like doesn't allow it? Like you

594
00:29:47,320 --> 00:29:49,680
Speaker 1: just don't know how to write it down, or like

595
00:29:50,000 --> 00:29:53,120
Speaker 1: you get nonsensical answers, or it's like trying to fit

596
00:29:53,160 --> 00:29:55,120
Speaker 1: a square peg in a round hole. You know, am

597
00:29:55,120 --> 00:29:57,800
Speaker 1: I trying to use fractions to you know, compute things

598
00:29:57,800 --> 00:29:59,600
Speaker 1: to certain decimal point or something.

599
00:30:00,080 --> 00:30:02,520
Speaker 2: Yeah, the mathematics of general relativity is hard.

600
00:30:02,560 --> 00:30:02,720
Speaker 1: You know.

601
00:30:02,760 --> 00:30:06,400
Speaker 2: It took Einstein like ten years to figure out how

602
00:30:06,400 --> 00:30:08,920
Speaker 2: to wrangle these equations to make any sense of them.

603
00:30:09,280 --> 00:30:11,840
Speaker 2: He had this idea that maybe space was curved and

604
00:30:11,880 --> 00:30:14,520
Speaker 2: that was explaining what gravity really was. But to make

605
00:30:14,520 --> 00:30:17,280
Speaker 2: the math work to even Einstein in a decade, and

606
00:30:17,320 --> 00:30:19,080
Speaker 2: it takes a lot of people a lot of time

607
00:30:19,120 --> 00:30:21,480
Speaker 2: to understand and to wrestle with the equations, which turn

608
00:30:21,560 --> 00:30:24,360
Speaker 2: out to be really really complicated. It's not like one

609
00:30:24,360 --> 00:30:27,520
Speaker 2: equation for a general relativity that says more mass means

610
00:30:27,560 --> 00:30:31,800
Speaker 2: more curvature. It's a matrix of equations. There's like sixteen

611
00:30:31,880 --> 00:30:35,440
Speaker 2: coupled equations which are really hairy, and if you add

612
00:30:35,440 --> 00:30:38,240
Speaker 2: to those the probability that space is may be curved

613
00:30:38,240 --> 00:30:42,160
Speaker 2: here and maybe curved there, it increases the complexity exponentially,

614
00:30:42,400 --> 00:30:44,960
Speaker 2: and it makes those equations impossible to even write down.

615
00:30:44,960 --> 00:30:47,680
Speaker 2: We don't know how to write down equations that both

616
00:30:47,760 --> 00:30:52,000
Speaker 2: describe space as a curvature of this differential geometric manifold

617
00:30:52,400 --> 00:30:55,360
Speaker 2: and allow for probabilities, like we just don't have the

618
00:30:55,360 --> 00:30:57,760
Speaker 2: tools for it. It might be that somebody out there

619
00:30:57,800 --> 00:31:02,360
Speaker 2: is developing some cool theory probabilistic manifolds that later will

620
00:31:02,400 --> 00:31:04,520
Speaker 2: be able to slip in to build the theory of

621
00:31:04,560 --> 00:31:07,360
Speaker 2: quantum gravity. But it's like we need a power tool

622
00:31:07,400 --> 00:31:08,800
Speaker 2: and all we have is a handsaw.

623
00:31:08,920 --> 00:31:10,360
Speaker 1: Yeah, Like you say, like if we just don't have

624
00:31:10,440 --> 00:31:13,640
Speaker 1: the right tools that will both fit a square peg

625
00:31:13,680 --> 00:31:14,600
Speaker 1: and a round hole.

626
00:31:14,440 --> 00:31:15,960
Speaker 2: And we don't know if we're missing the right tool,

627
00:31:16,000 --> 00:31:18,480
Speaker 2: Maybe that's just the wrong direction, right. It could be

628
00:31:18,560 --> 00:31:20,720
Speaker 2: that that's not the right way to try to build

629
00:31:20,720 --> 00:31:23,520
Speaker 2: the theory of quantum gravity. But a lot of times

630
00:31:23,560 --> 00:31:26,560
Speaker 2: it is the case that progress in mathematics is limiting

631
00:31:26,600 --> 00:31:29,760
Speaker 2: progress in physics. Einstein was only able to build general

632
00:31:29,800 --> 00:31:33,440
Speaker 2: relativity because the theories of differential geometry had been developed

633
00:31:33,480 --> 00:31:37,000
Speaker 2: like ten fifteen years earlier by mathematicians who didn't care

634
00:31:37,040 --> 00:31:39,800
Speaker 2: at all about gravity or physics. They just thought it

635
00:31:39,840 --> 00:31:42,760
Speaker 2: was cool to think about like wiggly shapes in their mind,

636
00:31:43,000 --> 00:31:44,840
Speaker 2: and so this kind of stuff happens all the time.

637
00:31:45,640 --> 00:31:48,080
Speaker 1: I see you're saying it's all the mathematicians fault, like

638
00:31:48,120 --> 00:31:49,640
Speaker 1: they're holding you back. Man.

639
00:31:49,840 --> 00:31:52,360
Speaker 2: Math is the language of physics, and in the end,

640
00:31:52,480 --> 00:31:55,719
Speaker 2: it's mathematical problems that are preventing us from building theories

641
00:31:55,720 --> 00:31:59,320
Speaker 2: of quantum gravity. And what you described is basically trying

642
00:31:59,360 --> 00:32:02,480
Speaker 2: to make space quantum mechanical. You can also go the

643
00:32:02,560 --> 00:32:04,200
Speaker 2: other direction, and you can say, well, what if we

644
00:32:04,320 --> 00:32:07,640
Speaker 2: try to make gravity itself quantum mechanical. What if we

645
00:32:07,680 --> 00:32:10,640
Speaker 2: try to describe the theory of gravity as a quantum

646
00:32:10,720 --> 00:32:14,720
Speaker 2: force instead of this whole crazy curvature of space and time,

647
00:32:15,040 --> 00:32:17,239
Speaker 2: And then you run into a completely different kind of

648
00:32:17,240 --> 00:32:18,800
Speaker 2: mathematical mm I see.

649
00:32:18,920 --> 00:32:21,320
Speaker 1: I think what you're saying is like each of these

650
00:32:21,320 --> 00:32:23,560
Speaker 1: two theories work, but only if they ignore each other.

651
00:32:23,720 --> 00:32:27,200
Speaker 1: Like quantum mechanics assumes that space doesn't bend and there

652
00:32:27,240 --> 00:32:30,600
Speaker 1: is no gravity. Basically gravity doesn't exist. To quantum mechanics,

653
00:32:31,040 --> 00:32:34,760
Speaker 1: and general relativity assumes that things are not fuzzy at

654
00:32:34,800 --> 00:32:37,880
Speaker 1: any level exactly, which works for a lot of situations,

655
00:32:37,880 --> 00:32:40,959
Speaker 1: but in some situations you have to take them into

656
00:32:41,000 --> 00:32:42,440
Speaker 1: account both at the same time.

657
00:32:42,360 --> 00:32:45,360
Speaker 2: Exactly, and it's amazing that both of them work. They

658
00:32:45,400 --> 00:32:47,840
Speaker 2: tell very different stories about what's really happening in the universe,

659
00:32:48,320 --> 00:32:50,960
Speaker 2: and in almost every scenario you can ignore one.

660
00:32:51,320 --> 00:32:51,600
Speaker 1: Right.

661
00:32:52,280 --> 00:32:54,120
Speaker 2: It's like you have two friends that are like different

662
00:32:54,200 --> 00:32:56,120
Speaker 2: kinds of movies or something, and most of the time

663
00:32:56,160 --> 00:32:57,960
Speaker 2: you can just ignore one friend and listen to the

664
00:32:58,000 --> 00:33:01,640
Speaker 2: other friend. But sometimes they have opinions about the same

665
00:33:01,720 --> 00:33:03,200
Speaker 2: kind of movie, and you're like, well, is this movie

666
00:33:03,200 --> 00:33:04,840
Speaker 2: good or bad? I don't know who to listen to.

667
00:33:05,480 --> 00:33:08,600
Speaker 2: And for general relativity and quantum mechanics, currently they only

668
00:33:08,640 --> 00:33:13,000
Speaker 2: overlap in places we cannot see inside black holes, so

669
00:33:13,040 --> 00:33:15,920
Speaker 2: we don't know who's fundamentally right, or if either of

670
00:33:15,960 --> 00:33:16,520
Speaker 2: them are right.

671
00:33:17,360 --> 00:33:19,520
Speaker 1: I see. It's like having a friend who only watches

672
00:33:19,520 --> 00:33:22,640
Speaker 1: sci fi movies and then having another friend who only

673
00:33:22,680 --> 00:33:25,840
Speaker 1: watches romantic comedies. And usually you can have perfectly good

674
00:33:25,880 --> 00:33:29,280
Speaker 1: conversations with either of them. But let's say science fiction

675
00:33:29,400 --> 00:33:32,000
Speaker 1: wrap the comedy comes out. Now there's true.

676
00:33:31,760 --> 00:33:34,040
Speaker 2: Exactly exactly right. Now you can't hang out with your

677
00:33:34,040 --> 00:33:35,760
Speaker 2: friends anymore, right, boom the universe.

678
00:33:36,640 --> 00:33:40,720
Speaker 1: You gotta stop watching movies. You can stage your couch

679
00:33:40,760 --> 00:33:45,040
Speaker 1: and just do physics and math all day. Has this

680
00:33:45,120 --> 00:33:46,200
Speaker 1: already happened to you, Ben?

681
00:33:47,400 --> 00:33:50,560
Speaker 2: I think Passengers was not a sci fi romantic comedy.

682
00:33:50,680 --> 00:33:53,719
Speaker 1: Oh there you go, And that was very controversial.

683
00:33:53,320 --> 00:33:54,000
Speaker 2: Man, exactly.

684
00:33:54,240 --> 00:33:58,640
Speaker 1: Nobody likes that we don't have the math tools or

685
00:33:58,680 --> 00:34:01,719
Speaker 1: framework or theories that let us tackle these two things

686
00:34:01,760 --> 00:34:03,240
Speaker 1: at the same time. What are some other ways that

687
00:34:03,240 --> 00:34:05,240
Speaker 1: make it hard to unify these two things?

688
00:34:05,400 --> 00:34:07,720
Speaker 2: So a really popular approach is to trying to make

689
00:34:07,720 --> 00:34:11,319
Speaker 2: a theory of quantum gravity that has a graviton. Say,

690
00:34:11,440 --> 00:34:14,120
Speaker 2: you know, Einstein, that was cute. We like your idea

691
00:34:14,120 --> 00:34:16,520
Speaker 2: of Kurt space time. It's pretty, but maybe it's just

692
00:34:16,520 --> 00:34:19,200
Speaker 2: fundamentally the wrong direction. Maybe if you zoom in, what

693
00:34:19,239 --> 00:34:21,640
Speaker 2: really is happening is that gravity is a force and

694
00:34:21,680 --> 00:34:26,040
Speaker 2: it's exchanging gravitons, and I mean, then we can describe

695
00:34:26,080 --> 00:34:28,520
Speaker 2: the whole theory of gravity back sort of as like

696
00:34:28,560 --> 00:34:32,120
Speaker 2: a quantized version of Newton's theory. And people have tried

697
00:34:32,160 --> 00:34:33,960
Speaker 2: to do this because that'd be pretty right if we

698
00:34:33,960 --> 00:34:36,160
Speaker 2: could just like add gravity to the standard model and

699
00:34:36,200 --> 00:34:39,840
Speaker 2: have another particle and ignore this whole curvature business. That

700
00:34:39,880 --> 00:34:40,560
Speaker 2: would be cool.

701
00:34:40,719 --> 00:34:42,319
Speaker 1: So that would be going back to the idea that

702
00:34:42,320 --> 00:34:45,080
Speaker 1: gravity is a force, not a bending of space and

703
00:34:45,120 --> 00:34:45,960
Speaker 1: time exactly.

704
00:34:46,120 --> 00:34:49,040
Speaker 2: So to tell philosophically a very different story from what

705
00:34:49,120 --> 00:34:52,040
Speaker 2: Einstein is telling us about how the universe works, they

706
00:34:52,040 --> 00:34:54,600
Speaker 2: would say there is no curvature. There are these tiny,

707
00:34:54,600 --> 00:34:57,879
Speaker 2: little invisible gravitons being passed back and forth. The same

708
00:34:57,920 --> 00:35:00,920
Speaker 2: way that like electromagnetism you think about in terms of

709
00:35:01,120 --> 00:35:04,200
Speaker 2: electric fields that are sort of like virtual photons being

710
00:35:04,239 --> 00:35:07,040
Speaker 2: passed back and forth, you can think of gravity in

711
00:35:07,160 --> 00:35:10,520
Speaker 2: terms of gravitons being passed back and forth. So that's

712
00:35:10,560 --> 00:35:13,680
Speaker 2: one direction. The problem is nobody can make that math

713
00:35:13,800 --> 00:35:16,600
Speaker 2: work either. When you do the calculations there and you

714
00:35:16,640 --> 00:35:19,000
Speaker 2: ask like, well, what happens if you try to collide

715
00:35:19,000 --> 00:35:22,560
Speaker 2: two black holes together, or even two protons together, you

716
00:35:22,600 --> 00:35:26,000
Speaker 2: get nonsense answers. You get answers like, well, the probability

717
00:35:26,000 --> 00:35:28,480
Speaker 2: of this happening is one hundred and fifty percent, and

718
00:35:28,520 --> 00:35:31,319
Speaker 2: the probability of that happening is one thousand percent, Just

719
00:35:31,320 --> 00:35:34,000
Speaker 2: like numbers that do not make sense you can't have

720
00:35:34,080 --> 00:35:38,640
Speaker 2: probabilities greater than one. But that's what these calculations spit out.

721
00:35:38,880 --> 00:35:40,759
Speaker 1: Like if you assume a gravitin exists, then you get

722
00:35:40,800 --> 00:35:45,600
Speaker 1: these weird answers, but more fundamentally, like you're ignoring general relativity, right,

723
00:35:45,680 --> 00:35:48,800
Speaker 1: You're ignoring things that a lot of experiments have verified

724
00:35:48,840 --> 00:35:51,279
Speaker 1: that Eisin was right, and so you're sort of not

725
00:35:51,360 --> 00:35:52,920
Speaker 1: really solving the problem, right, are you.

726
00:35:53,120 --> 00:35:54,720
Speaker 2: Well, you'd have to think about it as an upgrade

727
00:35:54,760 --> 00:35:57,560
Speaker 2: to general relativity. You'd have to reproduce all the predictions

728
00:35:57,560 --> 00:36:00,320
Speaker 2: of general relativity. So you need to develop a theory

729
00:36:00,360 --> 00:36:03,800
Speaker 2: of gravitons, which when you zoom out, looks a lot

730
00:36:03,840 --> 00:36:06,640
Speaker 2: like general relativity, and that people actually can do. There

731
00:36:06,680 --> 00:36:10,759
Speaker 2: are theories of quantum gravity that involve graviton exchange that

732
00:36:10,800 --> 00:36:13,279
Speaker 2: when you zoom out, look a lot like general relativity.

733
00:36:13,480 --> 00:36:15,399
Speaker 1: So space time is not being bent.

734
00:36:15,560 --> 00:36:17,560
Speaker 2: Yeah, they tell a different story, but they make the

735
00:36:17,560 --> 00:36:21,040
Speaker 2: same predictions about like the motions of objects.

736
00:36:20,880 --> 00:36:25,000
Speaker 1: Including things like gravitational ways and frame dragging and all that, all.

737
00:36:24,880 --> 00:36:27,000
Speaker 2: That kind of stuff. The problem is what happens at

738
00:36:27,000 --> 00:36:28,640
Speaker 2: the small scale when you try to think about like

739
00:36:29,000 --> 00:36:32,080
Speaker 2: when two particles scatter against each other, or when two

740
00:36:32,120 --> 00:36:35,560
Speaker 2: black holes are being eaten, then this theory breaks down.

741
00:36:35,760 --> 00:36:37,799
Speaker 1: But generativity still works for those.

742
00:36:37,920 --> 00:36:40,520
Speaker 2: General relativity still works for those. But we think it's wrong, right.

743
00:36:40,560 --> 00:36:43,440
Speaker 2: General relativity, we think is giving the wrong answer for

744
00:36:43,480 --> 00:36:46,080
Speaker 2: what happens when two protons collide or what's at the

745
00:36:46,080 --> 00:36:48,600
Speaker 2: heart of a black hole, because it's ignoring the quantum

746
00:36:48,600 --> 00:36:51,520
Speaker 2: mechanical effects. You try to build a theory of quantum

747
00:36:51,560 --> 00:36:55,080
Speaker 2: gravity that has gravitons and explains all of general relativity

748
00:36:55,400 --> 00:36:59,239
Speaker 2: and gives you a gravitational quantum mechanical prediction for what

749
00:36:59,280 --> 00:37:02,440
Speaker 2: happens when two particles collider, two black holes collide, Then

750
00:37:02,440 --> 00:37:04,319
Speaker 2: you get all sorts of nonsense. You get all sorts

751
00:37:04,320 --> 00:37:06,840
Speaker 2: of infinities that we don't know how to wrangle.

752
00:37:07,120 --> 00:37:10,279
Speaker 1: M I see, So graviton not a great ivid you

753
00:37:10,360 --> 00:37:11,719
Speaker 1: or one that hasn't worked so far?

754
00:37:12,160 --> 00:37:15,880
Speaker 2: Yeah, exactly. There are also sort of fundamental problems we

755
00:37:16,000 --> 00:37:18,640
Speaker 2: just don't know how to solve for quantum gravity, like

756
00:37:19,120 --> 00:37:22,560
Speaker 2: deep inconsistencies between the picture of the universe we get

757
00:37:22,560 --> 00:37:25,040
Speaker 2: from general relativity and the picture of the universe we

758
00:37:25,080 --> 00:37:28,160
Speaker 2: get from quantum mechanics about how physics should work. That

759
00:37:28,239 --> 00:37:30,120
Speaker 2: we just don't know how to reconcile. Well, what do

760
00:37:30,200 --> 00:37:32,360
Speaker 2: you mean, Like what like a deep principle in physics

761
00:37:32,480 --> 00:37:35,600
Speaker 2: is this idea of locality that things should be near

762
00:37:35,640 --> 00:37:38,560
Speaker 2: each other to affect each other, that you shouldn't have

763
00:37:38,680 --> 00:37:41,560
Speaker 2: like an electron over here affecting something really really far

764
00:37:41,600 --> 00:37:45,960
Speaker 2: away in the universe, especially in quantum mechanics, and in

765
00:37:46,040 --> 00:37:49,520
Speaker 2: quantum mechanics, we have this deep connection between the distances

766
00:37:49,560 --> 00:37:53,040
Speaker 2: between things and their energies. Like the reason that we

767
00:37:53,160 --> 00:37:56,080
Speaker 2: use the Large Hadron Collider to study really really really

768
00:37:56,120 --> 00:37:59,880
Speaker 2: tiny things is you need really high energy to study

769
00:38:00,080 --> 00:38:03,480
Speaker 2: really small distance scales. Like things that have a lot

770
00:38:03,520 --> 00:38:06,160
Speaker 2: of energy interact with each other very very.

771
00:38:06,000 --> 00:38:10,239
Speaker 1: Closely, because if things have low energy, then they don't

772
00:38:10,239 --> 00:38:11,600
Speaker 1: interact with the things around them.

773
00:38:11,880 --> 00:38:13,880
Speaker 2: If things have low energy, then they can interact with

774
00:38:13,920 --> 00:38:16,719
Speaker 2: stuff that's further away. Another way to think about it

775
00:38:16,760 --> 00:38:19,480
Speaker 2: is in terms of the wavelength of stuff. You know

776
00:38:19,560 --> 00:38:22,319
Speaker 2: that you need like really high energy photons to see

777
00:38:22,360 --> 00:38:25,480
Speaker 2: really really small stuff. With lower energy photons they have

778
00:38:25,480 --> 00:38:29,680
Speaker 2: a longer wavelength you can't like resolve small details. That's why,

779
00:38:29,719 --> 00:38:32,360
Speaker 2: for example, when you want pictures of really really tiny stuff,

780
00:38:32,680 --> 00:38:36,160
Speaker 2: you use high frequency photons you go beyond that to

781
00:38:36,239 --> 00:38:39,600
Speaker 2: use like electrons to take pictures of atoms, for example.

782
00:38:39,920 --> 00:38:41,560
Speaker 2: So you want to see the universe on a really

783
00:38:41,600 --> 00:38:44,000
Speaker 2: small scale, you need to use really high.

784
00:38:43,840 --> 00:38:47,280
Speaker 1: Energy probes, maybe to say high frequency instead of high energy.

785
00:38:47,440 --> 00:38:51,000
Speaker 2: Yeah, energy and frequency very closely connected. In quantum mechanics,

786
00:38:51,040 --> 00:38:54,640
Speaker 2: you need very high frequency stuff to see really short distances.

787
00:38:55,040 --> 00:38:55,760
Speaker 1: Okay, okay.

788
00:38:55,920 --> 00:38:59,239
Speaker 2: In general relativity they have the opposite relationship. As you

789
00:38:59,320 --> 00:39:03,800
Speaker 2: add energy to something in general relativity, then its influence

790
00:39:03,920 --> 00:39:08,279
Speaker 2: grows to longer distances. So quantum mechanics, higher energy means

791
00:39:08,320 --> 00:39:13,000
Speaker 2: shorter distances. In general relativity, higher energy means larger distances.

792
00:39:13,520 --> 00:39:16,360
Speaker 2: Like think about what happens to a black hole's radius.

793
00:39:16,640 --> 00:39:19,120
Speaker 2: As you add energy to a black hole, black hole

794
00:39:19,160 --> 00:39:22,840
Speaker 2: gets bigger, you add more energy, black hole keeps getting bigger.

795
00:39:23,160 --> 00:39:26,400
Speaker 2: The short styled radius, the distance from the singularity to

796
00:39:26,440 --> 00:39:29,080
Speaker 2: the event horizon, just keeps growing as the black hole

797
00:39:29,120 --> 00:39:32,400
Speaker 2: gets more massive. So, somehow general relativity doesn't have the

798
00:39:32,400 --> 00:39:37,240
Speaker 2: same relationship between energy and frequency and the distances involved.

799
00:39:37,280 --> 00:39:41,399
Speaker 2: They have like this deeply opposite relationship. This might sound

800
00:39:41,440 --> 00:39:45,040
Speaker 2: like sort of weirdly philosophically handwavy to you, but it

801
00:39:45,120 --> 00:39:46,120
Speaker 2: sort of tells.

802
00:39:45,840 --> 00:39:48,840
Speaker 1: You about it not at all. I don't know what

803
00:39:48,920 --> 00:39:49,200
Speaker 1: you mean.

804
00:39:50,320 --> 00:39:52,440
Speaker 2: But the reason it's important is that it tells us

805
00:39:52,440 --> 00:39:54,759
Speaker 2: that these two theories have like a fundamentally different sort

806
00:39:54,800 --> 00:39:58,040
Speaker 2: of philosophical foundation. Like one of them is very very local,

807
00:39:58,120 --> 00:40:00,759
Speaker 2: the other one is very non local. So when we

808
00:40:00,800 --> 00:40:03,280
Speaker 2: go to make a theory of quantum gravity, we're like, hmm,

809
00:40:03,280 --> 00:40:05,520
Speaker 2: these two things are kind of like very different. How

810
00:40:05,560 --> 00:40:07,600
Speaker 2: do we bring them together? It's like, how do you

811
00:40:07,640 --> 00:40:10,600
Speaker 2: get your science fiction fan friend and your rom com

812
00:40:10,719 --> 00:40:13,440
Speaker 2: fan friend together into a single movie If they have

813
00:40:13,640 --> 00:40:17,000
Speaker 2: just like really opposing needs for pacing and jokes and

814
00:40:17,040 --> 00:40:20,960
Speaker 2: whatever in the movie, it might be fundamentally impossible. If

815
00:40:20,960 --> 00:40:23,239
Speaker 2: these two things are so deeply in conflict.

816
00:40:23,480 --> 00:40:25,640
Speaker 1: It sounds like you're just kind of maybe saying the

817
00:40:25,640 --> 00:40:28,480
Speaker 1: same thing we talked about before, which is like, you know,

818
00:40:28,560 --> 00:40:31,879
Speaker 1: quantum gravity is good for things that are small, and

819
00:40:32,040 --> 00:40:34,480
Speaker 1: general relativity is good for things that are really big,

820
00:40:35,000 --> 00:40:37,880
Speaker 1: but there is a certain overlap between them, and that's

821
00:40:37,920 --> 00:40:38,880
Speaker 1: where you get into trouble.

822
00:40:39,040 --> 00:40:41,759
Speaker 2: Yeah, exactly, But I think there's one more layer there, Like,

823
00:40:41,840 --> 00:40:44,879
Speaker 2: imagine you have a singularity, so at the tiny little

824
00:40:44,920 --> 00:40:48,279
Speaker 2: spot with a huge amount of mass. Right, so it's

825
00:40:48,360 --> 00:40:51,880
Speaker 2: quantum mechanically important but also has a huge amount of mass.

826
00:40:52,160 --> 00:40:55,760
Speaker 2: General relativity says it affects things really really far away

827
00:40:55,840 --> 00:40:58,799
Speaker 2: because it creates a black hole. Who's event horizon can

828
00:40:58,920 --> 00:41:02,000
Speaker 2: be really really far away. Quantum mechanics says, no, it

829
00:41:02,000 --> 00:41:04,640
Speaker 2: can only interact with stuff really really nearby, because that's

830
00:41:04,719 --> 00:41:06,279
Speaker 2: really really tiny frequency.

831
00:41:06,560 --> 00:41:08,840
Speaker 1: Well, I would say that it can only interact quantum

832
00:41:08,840 --> 00:41:11,480
Speaker 1: mechanically with things that are close by, but then it

833
00:41:11,520 --> 00:41:14,680
Speaker 1: can interact through gravity or generativity for things that are

834
00:41:14,719 --> 00:41:17,360
Speaker 1: far away, like way back to the same spot.

835
00:41:19,160 --> 00:41:21,480
Speaker 2: Yeah, exactly, we're back to the same spot that if

836
00:41:21,480 --> 00:41:23,880
Speaker 2: you have quantum gravity, then you don't know can it

837
00:41:23,920 --> 00:41:27,280
Speaker 2: only interact nearby in its vicinity or can it interact

838
00:41:27,280 --> 00:41:31,000
Speaker 2: far away as well? Gravity says far away, Quantum mechanics

839
00:41:31,000 --> 00:41:33,920
Speaker 2: says nearby. We don't know what quantum gravity says. It

840
00:41:33,960 --> 00:41:36,480
Speaker 2: seems like maybe impossible to come up with a theory

841
00:41:36,480 --> 00:41:37,840
Speaker 2: that satisfies both m.

842
00:41:38,440 --> 00:41:40,120
Speaker 1: Just like it's impossible to come up with a good

843
00:41:40,239 --> 00:41:42,600
Speaker 1: sci fi rom com.

844
00:41:42,719 --> 00:41:45,200
Speaker 2: Exactly, they're fundamentally opposed.

845
00:41:45,320 --> 00:41:47,879
Speaker 1: All right, Well, let's dig into some of the other

846
00:41:47,920 --> 00:41:52,080
Speaker 1: ways that make it hard to unify generalativity and quantum mechanics.

847
00:41:52,120 --> 00:42:06,719
Speaker 1: But first, let's take another quick break. All right, we're

848
00:42:06,719 --> 00:42:11,279
Speaker 1: talking about quantum gravity. Can we unite quantum mechanics and

849
00:42:11,920 --> 00:42:15,240
Speaker 1: general relativity which has gravity in it? So far, Daniel,

850
00:42:15,239 --> 00:42:16,440
Speaker 1: you're saying it's really hard.

851
00:42:16,560 --> 00:42:19,480
Speaker 2: It's really hard. Some of the smartest people in the

852
00:42:19,600 --> 00:42:22,680
Speaker 2: universe have tried for decades and failed.

853
00:42:22,520 --> 00:42:25,120
Speaker 1: In the universe. That's a big claim.

854
00:42:25,440 --> 00:42:27,920
Speaker 2: Well, the smartest people in the universe, it could be

855
00:42:28,000 --> 00:42:30,839
Speaker 2: aliens out there much smarter than us. I don't know.

856
00:42:30,880 --> 00:42:32,920
Speaker 2: Are they people though? Are aliens people?

857
00:42:33,280 --> 00:42:35,840
Speaker 1: Well, you're assuming that the smartest people on Earth have

858
00:42:35,960 --> 00:42:36,800
Speaker 1: become physicists.

859
00:42:36,840 --> 00:42:39,439
Speaker 2: Oh that's a good point. Yeah, I know that people

860
00:42:39,480 --> 00:42:41,760
Speaker 2: out there who are like hedge fund bros.

861
00:42:41,800 --> 00:42:45,480
Speaker 1: Yeah, or cartoonist maybe you know. I'm just saying you're

862
00:42:45,480 --> 00:42:46,920
Speaker 1: sort of making a general assumption.

863
00:42:46,960 --> 00:42:49,359
Speaker 2: Here are you saying you're not a physicist? I think

864
00:42:49,680 --> 00:42:52,120
Speaker 2: years in basically you're a physicist by now.

865
00:42:52,320 --> 00:42:55,960
Speaker 1: Oh, if that's true, then I have a diploma for

866
00:42:56,000 --> 00:42:57,560
Speaker 1: you to sign. Yeah.

867
00:42:57,600 --> 00:43:00,000
Speaker 2: I think we gave you that podcast diploma physics.

868
00:43:00,200 --> 00:43:02,880
Speaker 1: Right, I'm so waiting for that in the mail. It

869
00:43:02,960 --> 00:43:04,959
Speaker 1: must have gotten lost. I guess you sent it, right.

870
00:43:05,840 --> 00:43:07,400
Speaker 2: But we sent it. Yeah, you should definitely get a

871
00:43:07,400 --> 00:43:09,480
Speaker 2: physical copy. You do like a discount at dollar.

872
00:43:09,520 --> 00:43:13,520
Speaker 1: Stories like this is an imaginary diploma again for an

873
00:43:13,600 --> 00:43:18,720
Speaker 1: imaginary field of study. All right, So it's hard to

874
00:43:18,760 --> 00:43:22,080
Speaker 1: combine these two big theories. We talked about how the

875
00:43:22,120 --> 00:43:24,799
Speaker 1: math makes it really difficult. The philosophy of them make

876
00:43:24,880 --> 00:43:26,719
Speaker 1: it really difficult. What are some other ways that make

877
00:43:26,760 --> 00:43:27,080
Speaker 1: it hard?

878
00:43:27,160 --> 00:43:29,800
Speaker 2: People argue about the fundamental story of space and time

879
00:43:30,360 --> 00:43:33,360
Speaker 2: that quantum gravity will have to tell us, because quantum

880
00:43:33,400 --> 00:43:37,280
Speaker 2: mechanics and general relativity really do tell very very different stories.

881
00:43:37,320 --> 00:43:39,799
Speaker 2: Here in quantum mechanics, we have kind of like a

882
00:43:39,840 --> 00:43:43,520
Speaker 2: Newtonian view of space and time. We say space and time,

883
00:43:43,640 --> 00:43:47,480
Speaker 2: they're backdrops, they're absolute, they're fixed, and we put quantum

884
00:43:47,520 --> 00:43:50,120
Speaker 2: fields on top of that space and time. We assume

885
00:43:50,440 --> 00:43:53,640
Speaker 2: that space and time already exists somehow, and we say

886
00:43:53,680 --> 00:43:56,360
Speaker 2: that this quantum fields in that space and time, and

887
00:43:56,400 --> 00:43:58,920
Speaker 2: those fields operate and they're part of space. But we

888
00:43:58,920 --> 00:44:02,120
Speaker 2: don't ask about where space comes from or what it is.

889
00:44:02,160 --> 00:44:04,880
Speaker 2: That's kind of stuff. It's like a fixed background, we

890
00:44:04,960 --> 00:44:09,320
Speaker 2: call it. But in general relativity, space time is dynamical.

891
00:44:09,360 --> 00:44:11,719
Speaker 2: It's not like fixed can bend and twist, and it

892
00:44:11,719 --> 00:44:15,799
Speaker 2: doesn't like exist inside some other kind of space. We

893
00:44:15,880 --> 00:44:19,280
Speaker 2: have this way to like calculate the relative distance between points,

894
00:44:19,719 --> 00:44:23,399
Speaker 2: but space itself is not like some new field that's

895
00:44:23,440 --> 00:44:26,759
Speaker 2: sitting inside some sort of meta space or superspace or

896
00:44:26,800 --> 00:44:30,480
Speaker 2: subspace or some other kind of space. It tells us

897
00:44:30,520 --> 00:44:34,320
Speaker 2: that there is no fixed background. So people describe general

898
00:44:34,320 --> 00:44:38,840
Speaker 2: relativity as background independent, like the universe. Space itself is

899
00:44:38,880 --> 00:44:43,160
Speaker 2: not sitting inside some sort of deeper box, and which

900
00:44:43,200 --> 00:44:44,799
Speaker 2: is kind of weird because it makes you feel a

901
00:44:44,800 --> 00:44:47,680
Speaker 2: little like unmoored from the foundations of reality.

902
00:44:48,600 --> 00:44:52,320
Speaker 1: But I guess maybe couldn't you just have quantum mechanics

903
00:44:52,360 --> 00:44:55,560
Speaker 1: sit on top of a bendy stretch hey space time,

904
00:44:56,360 --> 00:44:58,879
Speaker 1: you know, sort of like you know, the planet Earth

905
00:44:58,920 --> 00:45:01,480
Speaker 1: of the Sun or moving through space time and they're

906
00:45:01,480 --> 00:45:05,000
Speaker 1: getting they're flowing through the curvature and all the bending.

907
00:45:05,480 --> 00:45:08,920
Speaker 1: Couldn't you have quantum fields also kind of right on

908
00:45:09,000 --> 00:45:11,279
Speaker 1: top of the curves of space time. Mm hmm.

909
00:45:11,480 --> 00:45:14,719
Speaker 2: And I love how you just like casually suggesting these solutions,

910
00:45:15,040 --> 00:45:17,400
Speaker 2: which are like the whole areas of research.

911
00:45:18,080 --> 00:45:22,600
Speaker 1: Working for twenty years, Daniel, come on, I mean I

912
00:45:22,680 --> 00:45:24,880
Speaker 1: just spent five to twenty minutes talking about this, and

913
00:45:24,920 --> 00:45:26,720
Speaker 1: I already know how to come up with the answer.

914
00:45:27,480 --> 00:45:30,279
Speaker 2: You're basically a business so long. No, I don't mean

915
00:45:30,320 --> 00:45:32,000
Speaker 2: to make it at all. I mean that these are

916
00:45:32,120 --> 00:45:34,640
Speaker 2: actually really clever ways forward, and these are exactly the

917
00:45:34,640 --> 00:45:37,520
Speaker 2: things that people are working on at the cutting edge.

918
00:45:37,600 --> 00:45:40,840
Speaker 2: It turns out to be complicated. You can do quantum

919
00:45:40,840 --> 00:45:44,279
Speaker 2: mechanics on curved space, you can put these fields on

920
00:45:44,480 --> 00:45:48,200
Speaker 2: curved space time, and mostly it works as long as

921
00:45:48,239 --> 00:45:51,440
Speaker 2: the curvature is small, So like if they're a little

922
00:45:51,440 --> 00:45:54,080
Speaker 2: bit curved, things are fine. As soon as the curvature

923
00:45:54,120 --> 00:45:56,960
Speaker 2: becomes large, you get back to all those crazy infinities

924
00:45:56,960 --> 00:45:59,920
Speaker 2: that we can't wrangle in all sorts of nonsense predictions.

925
00:46:00,280 --> 00:46:03,840
Speaker 2: So the quantum mechanical theory breaks down if the curvature

926
00:46:03,920 --> 00:46:06,120
Speaker 2: is really really high. So we just don't know how

927
00:46:06,160 --> 00:46:07,759
Speaker 2: to do those kinds of calculations.

928
00:46:08,040 --> 00:46:08,200
Speaker 3: Mm.

929
00:46:09,640 --> 00:46:12,719
Speaker 1: And that includes time, right because like in general relativity,

930
00:46:13,160 --> 00:46:15,880
Speaker 1: time can slow down and time can speed up. And

931
00:46:15,920 --> 00:46:17,120
Speaker 1: so you're saying you don't know how to do that

932
00:46:17,160 --> 00:46:18,640
Speaker 1: in quantum mechanics.

933
00:46:18,280 --> 00:46:20,680
Speaker 2: Exactly, we don't know how to do that in quantum mechanics. Again,

934
00:46:20,760 --> 00:46:23,400
Speaker 2: when the curvature is high, for what they call weak

935
00:46:23,520 --> 00:46:26,880
Speaker 2: field gravity, where it's like a very small effect gravity,

936
00:46:27,120 --> 00:46:29,920
Speaker 2: then we can do those calculations and even feel the

937
00:46:29,920 --> 00:46:33,360
Speaker 2: influence of gravity, not just negligible gravity, just weak gravity.

938
00:46:33,600 --> 00:46:36,000
Speaker 2: But when gravity gets strong, which is what it does

939
00:46:36,120 --> 00:46:38,600
Speaker 2: near a black hole, where we think these two things

940
00:46:38,640 --> 00:46:41,480
Speaker 2: are both important, we don't know how to do those calculations.

941
00:46:41,560 --> 00:46:45,040
Speaker 2: That's when quantum mechanics on curve space breaks down because

942
00:46:45,040 --> 00:46:47,600
Speaker 2: of all these infinities we can't grapple with all.

943
00:46:47,680 --> 00:46:51,360
Speaker 1: Right, Well, as we mentioned, we're not quite experts in

944
00:46:51,440 --> 00:46:54,400
Speaker 1: this topic, but we don't Maybe we will talk to

945
00:46:54,480 --> 00:46:56,440
Speaker 1: one of the smartest people in the universe who is

946
00:46:56,800 --> 00:46:58,640
Speaker 1: tackling this problem directly.

947
00:46:59,040 --> 00:47:02,600
Speaker 2: That's right down to Nathan, whose father is a listener

948
00:47:02,600 --> 00:47:05,400
Speaker 2: of the podcast and listen to the podcast mostly so

949
00:47:05,440 --> 00:47:08,440
Speaker 2: you can have a hope of understanding his son's research.

950
00:47:08,880 --> 00:47:11,960
Speaker 2: Nathan is a physics brad student at Arizona State University,

951
00:47:12,280 --> 00:47:15,960
Speaker 2: a well known department with experts in cosmology and theories

952
00:47:16,000 --> 00:47:18,760
Speaker 2: of quantum gravity, and he was kind enough to spend

953
00:47:18,760 --> 00:47:21,680
Speaker 2: five minutes talking to me about his research and so.

954
00:47:21,640 --> 00:47:25,719
Speaker 1: Here at Daniel's interview with Nathan Berwick, Quantum Gravity researcher.

955
00:47:26,440 --> 00:47:30,000
Speaker 2: So then it's my pleasure to welcome Nathan to the podcast. Nathan,

956
00:47:30,160 --> 00:47:33,040
Speaker 2: please introduce yourself and tell the listeners who you are.

957
00:47:33,800 --> 00:47:39,000
Speaker 3: Yes, I'm Nathan Berwick. I'm currently a first year PhD

958
00:47:39,080 --> 00:47:46,080
Speaker 3: student at Arizona State University studying physics and cosmology and

959
00:47:46,239 --> 00:47:51,160
Speaker 3: hoping to continue doing so and move into ideally stuff

960
00:47:51,200 --> 00:47:52,680
Speaker 3: along the lines of quantum gravity.

961
00:47:52,800 --> 00:47:55,960
Speaker 2: Awesome. Well, we often talk on the podcast about how

962
00:47:56,080 --> 00:47:58,919
Speaker 2: science is just a bunch of people following their curiosity

963
00:47:59,040 --> 00:48:02,080
Speaker 2: and pushing forward the forefront of knowledge. So tell us

964
00:48:02,120 --> 00:48:05,480
Speaker 2: what is it about physics and gr that drew you in,

965
00:48:05,560 --> 00:48:08,080
Speaker 2: that made you decide you want to spend your life

966
00:48:08,200 --> 00:48:09,240
Speaker 2: on this question.

967
00:48:10,040 --> 00:48:13,480
Speaker 3: That's a really good question. So I think part of

968
00:48:13,520 --> 00:48:15,359
Speaker 3: it is just I always kind of grew up as

969
00:48:15,440 --> 00:48:18,919
Speaker 3: a curious kid, and you know, when I was younger,

970
00:48:18,960 --> 00:48:21,080
Speaker 3: I always knew I wanted to be like a scientist

971
00:48:21,239 --> 00:48:26,000
Speaker 3: in air quotes. But eventually I sort of narrowed in

972
00:48:26,040 --> 00:48:29,840
Speaker 3: on physics, and I think as soon as I learned

973
00:48:29,840 --> 00:48:32,680
Speaker 3: about like the most basic concepts in general relativity, sort

974
00:48:32,680 --> 00:48:35,759
Speaker 3: of the idea that space time is one great big

975
00:48:35,760 --> 00:48:38,520
Speaker 3: thing and gravity is just the curvature of that it

976
00:48:38,600 --> 00:48:42,600
Speaker 3: was just immediately alluring, especially when you start to consider

977
00:48:43,560 --> 00:48:47,120
Speaker 3: how gravity is, like are most interacted with force at

978
00:48:47,200 --> 00:48:50,120
Speaker 3: least sort of perceptually. You know, we talk about it

979
00:48:50,160 --> 00:48:53,600
Speaker 3: a lot. You don't really talk about how electromagnet doesn't

980
00:48:53,640 --> 00:48:56,080
Speaker 3: really plays a role in your life very often. But

981
00:48:56,440 --> 00:49:01,359
Speaker 3: it's also very poorly understood in general, and there's still

982
00:49:01,400 --> 00:49:04,200
Speaker 3: like a lot of really big open questions to be

983
00:49:04,280 --> 00:49:07,320
Speaker 3: answered for general relativity. And I think that sort of

984
00:49:07,400 --> 00:49:11,759
Speaker 3: openness is very much an invitation to explore, which I

985
00:49:11,800 --> 00:49:12,200
Speaker 3: really like.

986
00:49:12,360 --> 00:49:14,000
Speaker 2: So you're not going to give your dad any credit

987
00:49:14,040 --> 00:49:15,920
Speaker 2: for encouraging you to study physics.

988
00:49:17,280 --> 00:49:19,040
Speaker 5: I think, I think I definitely should.

989
00:49:20,200 --> 00:49:24,080
Speaker 3: Yeah, No, he definitely like fostered my curiosity in physics

990
00:49:24,120 --> 00:49:26,600
Speaker 3: growing up. Both my parents did, but my dad was

991
00:49:26,640 --> 00:49:30,080
Speaker 3: always fascinated in physics, and so from just like really

992
00:49:30,120 --> 00:49:33,680
Speaker 3: small things, you know, we'd always find questions on the internet,

993
00:49:33,719 --> 00:49:35,319
Speaker 3: you know, whether it be a bad string theory, which

994
00:49:35,360 --> 00:49:37,800
Speaker 3: is always like a very big, you know, media topic

995
00:49:37,840 --> 00:49:40,200
Speaker 3: and whatnot. But he definitely played a very big role

996
00:49:40,600 --> 00:49:41,920
Speaker 3: in me wanting to do physics.

997
00:49:42,680 --> 00:49:45,239
Speaker 2: So a lot of people say that general relativity, once

998
00:49:45,280 --> 00:49:48,799
Speaker 2: you fully understand it, is deep and beautiful. Do you

999
00:49:48,840 --> 00:49:51,120
Speaker 2: have that kind of esthetic reaction to it?

1000
00:49:51,600 --> 00:49:53,239
Speaker 3: Yeah, I think a lot of the beauty of it

1001
00:49:53,280 --> 00:49:57,719
Speaker 3: comes from the idea alone that it's all just curvat true,

1002
00:49:58,560 --> 00:50:01,960
Speaker 3: that gravity is in essence just curvature of this big

1003
00:50:02,480 --> 00:50:05,080
Speaker 3: manifold which you may or may not well, which you

1004
00:50:05,080 --> 00:50:08,439
Speaker 3: can't really visualize. But that, for me is the part

1005
00:50:08,440 --> 00:50:13,279
Speaker 3: of the esthetic that general relativity has is just like

1006
00:50:13,320 --> 00:50:15,520
Speaker 3: a breakdown into a more fundamental concept.

1007
00:50:15,800 --> 00:50:19,279
Speaker 2: So if gr is so gorgeous and it works so well,

1008
00:50:19,360 --> 00:50:22,640
Speaker 2: all these experiments confirming Einstein all the time, how can

1009
00:50:22,640 --> 00:50:25,000
Speaker 2: it be wrong? I mean, is it wrong in the

1010
00:50:25,040 --> 00:50:28,000
Speaker 2: way that like Newton's gravity is wrong where it was

1011
00:50:28,040 --> 00:50:31,120
Speaker 2: telling fundamentally the wrong story about what was happening but

1012
00:50:31,160 --> 00:50:33,759
Speaker 2: we didn't really notice until we dug into the details.

1013
00:50:34,400 --> 00:50:37,439
Speaker 2: Or is it mostly telling the right story just needs

1014
00:50:37,480 --> 00:50:40,160
Speaker 2: some like corrections and band aids here and there.

1015
00:50:40,440 --> 00:50:40,720
Speaker 5: Yeah.

1016
00:50:40,760 --> 00:50:43,360
Speaker 3: So that's a really good question, and I think it

1017
00:50:43,360 --> 00:50:46,600
Speaker 3: really depends on how much of the last one hundred

1018
00:50:46,680 --> 00:50:50,759
Speaker 3: years you're willing to disregard, and you know that that

1019
00:50:50,880 --> 00:50:54,480
Speaker 3: has certain consequences but also benefits. But I think the

1020
00:50:54,520 --> 00:51:00,520
Speaker 3: most generally accepted perspective right now is that it needs

1021
00:50:59,800 --> 00:51:05,960
Speaker 3: because general relativity, as this idea of gravity being caused

1022
00:51:05,960 --> 00:51:10,440
Speaker 3: by space time curvature, is so so rigorously tested at

1023
00:51:10,480 --> 00:51:13,480
Speaker 3: the moment, you know, we keep trying to knock Einstein

1024
00:51:13,560 --> 00:51:17,160
Speaker 3: down and find errors in his theory somewhere, but every

1025
00:51:17,239 --> 00:51:22,080
Speaker 3: single time like he just was right. And so that's

1026
00:51:22,080 --> 00:51:25,600
Speaker 3: a difficult thing to try and find errors in. But

1027
00:51:25,640 --> 00:51:30,920
Speaker 3: there's obviously still big questions. So quantum gravity is probably

1028
00:51:30,920 --> 00:51:36,279
Speaker 3: the largest area of questions regarding general relativity, and a

1029
00:51:36,280 --> 00:51:39,160
Speaker 3: lot of that has to do with just quantum mechanics

1030
00:51:39,160 --> 00:51:41,879
Speaker 3: not playing nicely when you try and think about how

1031
00:51:41,920 --> 00:51:44,600
Speaker 3: gravitational fields work with it. General relativity doesn't have any

1032
00:51:44,640 --> 00:51:49,560
Speaker 3: fundamental understanding of what probability distribution looks like. There's no

1033
00:51:49,719 --> 00:51:54,200
Speaker 3: like wave function understanding when you start getting into the

1034
00:51:54,320 --> 00:51:56,279
Speaker 3: smaller regimes for general relativity.

1035
00:51:56,760 --> 00:51:59,320
Speaker 2: So that's a really big topic, like general relativity and

1036
00:51:59,360 --> 00:52:02,279
Speaker 2: quantm mechanics. What are you actually researching right now? Like

1037
00:52:02,320 --> 00:52:04,720
Speaker 2: what are you working on today today?

1038
00:52:04,960 --> 00:52:09,680
Speaker 3: So throughout the last semester, I've been working on what

1039
00:52:09,719 --> 00:52:13,600
Speaker 3: are called scalar tensor theories, which I actually think you

1040
00:52:13,640 --> 00:52:16,759
Speaker 3: guys did an episode fairly recently on no hair theorems.

1041
00:52:16,800 --> 00:52:20,680
Speaker 3: For black holes, and that's very much what I'm working

1042
00:52:20,680 --> 00:52:24,719
Speaker 3: on at the moment, just showing that there's no sort

1043
00:52:24,760 --> 00:52:28,920
Speaker 3: of scalar hairs for certain types of theories.

1044
00:52:29,200 --> 00:52:32,760
Speaker 2: Cool. So then I'm gonna ask you to speculate unscientifically.

1045
00:52:33,320 --> 00:52:36,200
Speaker 2: What do you think is inside a black hole?

1046
00:52:37,719 --> 00:52:38,640
Speaker 5: Oh? Boy?

1047
00:52:38,800 --> 00:52:41,400
Speaker 3: What do I think is inside a black hole? Speculative

1048
00:52:41,400 --> 00:52:43,520
Speaker 3: answer is, well, if it's a big black hole, there's

1049
00:52:43,520 --> 00:52:46,440
Speaker 3: probably stuff sort of floating around in there being eaten up.

1050
00:52:46,520 --> 00:52:51,160
Speaker 3: But I like to think that there's this sort of

1051
00:52:51,200 --> 00:52:56,560
Speaker 3: taboo in physics of natural infinities. They aren't there're usually

1052
00:52:56,560 --> 00:53:00,160
Speaker 3: when there's an infinity, it's something horribly horribly wrong. And

1053
00:53:00,200 --> 00:53:02,520
Speaker 3: that was sort of the big hub up when they

1054
00:53:02,560 --> 00:53:04,560
Speaker 3: figured out that black holes could be a thing that

1055
00:53:04,640 --> 00:53:08,200
Speaker 3: actually existed, was that it just felt wrong that there

1056
00:53:08,200 --> 00:53:12,200
Speaker 3: could be such a dense object that's just so infinitely packed.

1057
00:53:12,719 --> 00:53:15,000
Speaker 3: I like to think that it is just, you know,

1058
00:53:15,120 --> 00:53:20,200
Speaker 3: a perfectly oh infinite density singularity, just because I think

1059
00:53:20,840 --> 00:53:24,279
Speaker 3: it'd be very wild and wacky and cool to have

1060
00:53:24,320 --> 00:53:30,279
Speaker 3: this very strange yet natural like divergence or infinity just

1061
00:53:30,400 --> 00:53:31,640
Speaker 3: existing in the universe.

1062
00:53:32,000 --> 00:53:34,640
Speaker 2: Do you think the singularity inside a black hole is

1063
00:53:34,719 --> 00:53:38,000
Speaker 2: as dense as boba, you know, these chewy blobs of

1064
00:53:38,040 --> 00:53:41,759
Speaker 2: death that people inexplicably like shooting up their straws as

1065
00:53:41,760 --> 00:53:44,799
Speaker 2: they enjoy and otherwise relaxing beverage. I happen to know

1066
00:53:44,960 --> 00:53:46,560
Speaker 2: your father agrees with me on this.

1067
00:53:49,480 --> 00:53:51,680
Speaker 5: He sent me a clip of this just the other day.

1068
00:53:54,960 --> 00:53:57,319
Speaker 3: I certainly hope that boba is it not at all

1069
00:53:57,480 --> 00:54:01,759
Speaker 3: comparable to singularities. But I suppose you never know what

1070
00:54:01,960 --> 00:54:05,200
Speaker 3: that would be, the hell that my dad would die on.

1071
00:54:05,280 --> 00:54:08,080
Speaker 2: I think, well, I think maybe your dad should open

1072
00:54:08,160 --> 00:54:11,320
Speaker 2: up a black hole boba shop that sells black hole boba,

1073
00:54:11,600 --> 00:54:16,479
Speaker 2: super dense, super dense little chunks of destruction. All right, Nathan,

1074
00:54:16,520 --> 00:54:18,719
Speaker 2: thanks very much for taking some time to talk to

1075
00:54:18,800 --> 00:54:21,400
Speaker 2: us about your work on the forefront of understanding of

1076
00:54:21,400 --> 00:54:24,080
Speaker 2: general relativity, and good luck figuring it all out.

1077
00:54:24,640 --> 00:54:26,279
Speaker 5: Thank you very much. Thank you for having me.

1078
00:54:27,560 --> 00:54:32,680
Speaker 1: All right, interesting chat there, pretty controversial about both boba

1079
00:54:32,719 --> 00:54:33,480
Speaker 1: and black holes.

1080
00:54:34,280 --> 00:54:36,760
Speaker 2: You know, this is the cutting edge of food science

1081
00:54:36,880 --> 00:54:38,640
Speaker 2: and quantum gravity.

1082
00:54:38,520 --> 00:54:44,719
Speaker 1: That's right, and sugary drinks, yes, But it's interesting that

1083
00:54:45,360 --> 00:54:48,200
Speaker 1: he seems to follow pretty strongly on the general latuty side.

1084
00:54:48,200 --> 00:54:50,439
Speaker 1: He thinks inside of black holes are singularities.

1085
00:54:50,560 --> 00:54:53,800
Speaker 2: Yeah, I've seen this in a lot of quantum gravity theorists,

1086
00:54:53,840 --> 00:54:57,839
Speaker 2: that they are intoxicated by the beauty of general relativity.

1087
00:54:58,239 --> 00:55:01,000
Speaker 2: It's sort of hard to overstate the this has on people.

1088
00:55:01,040 --> 00:55:04,239
Speaker 2: When they are able to import Einstein's equations into their

1089
00:55:04,280 --> 00:55:06,920
Speaker 2: mind and they can see the universe in terms of

1090
00:55:06,960 --> 00:55:10,240
Speaker 2: this differential manifold, they feel like the scales have fallen

1091
00:55:10,280 --> 00:55:12,120
Speaker 2: from their eyes and they're seeing the universe the way

1092
00:55:12,120 --> 00:55:14,560
Speaker 2: it really is, and it has to be true. So

1093
00:55:14,640 --> 00:55:17,520
Speaker 2: they want to preserve this vision of the universe as

1094
00:55:17,520 --> 00:55:21,480
Speaker 2: having curved space time. It's not exactly religious, but it's

1095
00:55:21,480 --> 00:55:23,239
Speaker 2: almost like a spiritual experience.

1096
00:55:23,480 --> 00:55:26,440
Speaker 1: Oh my goodness. This is coming from, of course, a

1097
00:55:26,520 --> 00:55:30,560
Speaker 1: quantum mechanics particle researcher. Right, you're trying to say that

1098
00:55:30,760 --> 00:55:34,000
Speaker 1: the other side are a bunch of religious zillids because

1099
00:55:34,040 --> 00:55:35,480
Speaker 1: your side is obviously right.

1100
00:55:35,560 --> 00:55:38,120
Speaker 2: I mean, they like boba, so so you can't trust

1101
00:55:38,120 --> 00:55:38,759
Speaker 2: them at all.

1102
00:55:40,440 --> 00:55:42,919
Speaker 1: Well, boba are like particles, so I would have thought

1103
00:55:42,960 --> 00:55:44,840
Speaker 1: they're fuzzy particles, so I would have value you be

1104
00:55:44,920 --> 00:55:45,440
Speaker 1: a big fan.

1105
00:55:45,600 --> 00:55:47,920
Speaker 2: No, they're macroscopic, man, They're dominated by gravity.

1106
00:55:48,080 --> 00:55:52,480
Speaker 1: Mm. Well, I wonder if maybe there is a singularity,

1107
00:55:52,520 --> 00:55:55,400
Speaker 1: you know, and maybe it's also fuzzy at the center

1108
00:55:55,440 --> 00:55:57,680
Speaker 1: of it. It's just that maybe in a singularity, space

1109
00:55:57,880 --> 00:56:02,040
Speaker 1: is so compressed or so squish together, that maybe the

1110
00:56:02,360 --> 00:56:04,279
Speaker 1: quantum certainties also get squished down.

1111
00:56:04,520 --> 00:56:06,600
Speaker 2: Maybe we're gonna solve quantum gravity right here on this

1112
00:56:06,640 --> 00:56:07,680
Speaker 2: podcast today.

1113
00:56:08,000 --> 00:56:11,440
Speaker 1: Yeah, yeah, let's do it. Why wait one hundred years,

1114
00:56:11,520 --> 00:56:14,040
Speaker 1: let's come up with that romantic comedy sci fi movie

1115
00:56:14,160 --> 00:56:14,520
Speaker 1: right now?

1116
00:56:14,600 --> 00:56:17,759
Speaker 2: Why is quantum gravity so hard? Because nobody asked a cartoonist.

1117
00:56:18,280 --> 00:56:23,239
Speaker 2: There you go, boom, question answered, boom.

1118
00:56:23,320 --> 00:56:28,719
Speaker 1: Done. Let's go tackle something harder, like cancer or democracy.

1119
00:56:31,120 --> 00:56:34,560
Speaker 1: All right, Well, you're on one side, people like Nathan

1120
00:56:34,600 --> 00:56:36,680
Speaker 1: are on the other side. Sounds like we still have

1121
00:56:36,719 --> 00:56:37,319
Speaker 1: a long way to go.

1122
00:56:37,480 --> 00:56:38,960
Speaker 2: We do have a long way to go, and there

1123
00:56:38,960 --> 00:56:43,440
Speaker 2: are deep philosophical and mathematical hurdles to overcome. We want

1124
00:56:43,560 --> 00:56:45,440
Speaker 2: to have a single theory of the universe, one that

1125
00:56:45,560 --> 00:56:48,440
Speaker 2: gives us a complete picture of what's really happening the

1126
00:56:48,480 --> 00:56:51,920
Speaker 2: source code for the universe. But so far none of

1127
00:56:51,960 --> 00:56:54,000
Speaker 2: our attempts actually compute.

1128
00:56:53,640 --> 00:56:56,400
Speaker 1: And so it's an active area of research, maybe waiting

1129
00:56:56,440 --> 00:56:59,960
Speaker 1: for the next person to tackle this and possibly solve it,

1130
00:57:00,480 --> 00:57:03,240
Speaker 1: and that could be you out there asking these questions,

1131
00:57:03,320 --> 00:57:06,840
Speaker 1: listening to this podcast, wondering how the universe works.

1132
00:57:06,960 --> 00:57:10,400
Speaker 2: I hope that future genius doesn't suffer an unfortunate boba accident,

1133
00:57:10,760 --> 00:57:14,040
Speaker 2: choking to death before they can share their insights with humanity.

1134
00:57:14,160 --> 00:57:18,080
Speaker 1: Oh my gosh, it's a little bit dark there, a

1135
00:57:18,120 --> 00:57:20,720
Speaker 1: little bit dark. I think you need a pretty large

1136
00:57:20,720 --> 00:57:22,280
Speaker 1: bubba ball. There's choking.

1137
00:57:22,360 --> 00:57:24,920
Speaker 2: Then it's boba relativity.

1138
00:57:25,120 --> 00:57:27,960
Speaker 1: That's right, the answer, the choking hazard of a boba

1139
00:57:28,480 --> 00:57:32,000
Speaker 1: is really all right. Well, stay tuned. You hope you

1140
00:57:32,080 --> 00:57:35,320
Speaker 1: enjoyed that. Thanks for joining us, See you next night.

1141
00:57:39,320 --> 00:57:42,200
Speaker 2: For more science and curiosity, come find us on social

1142
00:57:42,240 --> 00:57:47,200
Speaker 2: media where we answer questions and post videos. We're on Twitter, Discord, Instant,

1143
00:57:47,240 --> 00:57:50,960
Speaker 2: and now TikTok. Thanks for listening, and remember that Daniel

1144
00:57:51,000 --> 00:57:54,440
Speaker 2: and Jorge Explain the Universe is a production of iHeart Radio.

1145
00:57:54,720 --> 00:57:58,600
Speaker 2: For more podcasts from iHeart Radio, visit the iHeartRadio app,

1146
00:57:58,880 --> 00:58:02,320
Speaker 2: Apple Podcasts, or wherever you listen to your favorite shows.