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Speaker 1: Hey, Daniel, is it true that every electron is identical?

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Speaker 2: Well, they all do have the same mass and the

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Speaker 2: same charge, Like exactly, yeah, we think so.

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Speaker 1: Isn't that weird? Why don't you expect them to be

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Speaker 1: a little bit different each one.

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Speaker 2: It's kind of exactly not weird. It means that no

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Speaker 2: electrons are weird because they are all the same.

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Speaker 1: I don't know, man, that's a bit wooky. Like if

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Speaker 1: everyone in your neighborhood looked the same, wouldn't that be weird?

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Speaker 2: I mean, I live in Orange County, so that's kind

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Speaker 2: of what most people in the neighborhood are going for.

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Speaker 1: Everyone's going for that scruffy physicist.

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Speaker 2: Look more like plastic surgery face and beige housing.

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Speaker 3: Well.

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Speaker 1: I didn't want to say anything, but yeah, I do

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Speaker 1: feel like you need a facelift in or at least

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Speaker 1: a physics lift. Hi. I'm jorm At, cartoonist and the

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Speaker 1: author of Oliver's 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'm proud of being one of

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Speaker 2: a kind.

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Speaker 1: But what kind is that? Daniel?

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Speaker 2: That's the quiet that you. The pride might depend On. Mm, yeah,

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Speaker 2: I define my kind man. There's nobody else like me. M.

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Speaker 1: How do you know, though, have you met everyone who's

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Speaker 1: ever existed? What if there was a Daniel with your

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Speaker 1: exact same DNA that you know, lived two hundred years

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Speaker 1: ago or could be living right now.

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Speaker 2: It's possible, but they wouldn't have the same experiences. I

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Speaker 2: have actually met another Daniel Whitson. He's an artist in

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Speaker 2: the UK and quite accomplished.

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Speaker 1: Ooh are you jealous?

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Speaker 2: Am I jealous of the artist lifestyle?

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Speaker 3: Oh?

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Speaker 2: So many directions to go with that?

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Speaker 1: What was that like? I don't think I've ever met

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Speaker 1: a horhe Cham yet, but I think one exists somewhere

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Speaker 1: in Indonesia.

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Speaker 2: Maybe isn't there another one who has the Twitter handle

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Speaker 2: at hohorhey.

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Speaker 1: Cham somebody got that Twitter handle. I don't know if

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Speaker 1: it is horri ha Jam or not, but I'm waiting

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Speaker 1: for the blackmail email. Mm.

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Speaker 2: Yeah, well, at least a digital copy of you exists.

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Speaker 1: Or maybe I opened it years ago, but I forgot

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Speaker 1: the password and the email I associated it with, so

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Speaker 1: I don't know. Maybe I am my other meat.

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Speaker 2: Yeah. Maybe we're old enough that younger versions of us

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Speaker 2: are like alien minds.

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Speaker 1: Oh wait, wouldn't that make you an alien?

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Speaker 2: I think we're all still struggling to know ourselves.

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Speaker 1: Right, well, we might all be aliens, right that Isn't

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Speaker 1: there a theory that maybe life came to Earth from Mars.

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Speaker 2: There is a theory like that called panspermia, that life

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Speaker 2: may have originated somewhere else in the universe and then

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Speaker 2: transported microbially hidden inside asteroids. It's a possibility all immigrants,

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Speaker 2: kind of.

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Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain

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Speaker 1: the Universe, a production of iHeartRadio in.

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Speaker 2: Which we do our best to digest this alien universe

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Speaker 2: to explain all of the bizarre and amazing effects we

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Speaker 2: see out there in terms of little mathematical stories that

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Speaker 2: your mind and my mind and Jorge's mind can actually

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Speaker 2: understand that we can talk about and digest and explain

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Speaker 2: to you.

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Speaker 1: That's right, because it is a pretty vast universe, and

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Speaker 1: it's also pretty weird, full of unexplained phenomenon, unanswered questions,

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Speaker 1: and potentially other versions of you out there.

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Speaker 2: Raising all sorts of interesting philosophical questions like what does

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Speaker 2: it mean to have an identical copy? And when you

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Speaker 2: step into a transporter on Star Trek. Is it making

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Speaker 2: a copy or actually transporting you?

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Speaker 1: And what if, like there's another Jorge and another Daniel

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Speaker 1: and they start a podcast. Can we sue them technically

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Speaker 1: or maybe just retiring and give them the feat?

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Speaker 2: Yeah, maybe it's time for the next generation, right.

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Speaker 1: The new Daniel and Jorge explain the universe? Or Daniel

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Speaker 1: and Horry explained the universe the next generation?

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Speaker 2: Exactly? Yeah, one of us is Jean Luke and the

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Speaker 2: other one is Riker.

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Speaker 1: Wait wait, wait your name comes first, as I mean,

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Speaker 1: I'm number two?

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Speaker 2: Make it so? Okay?

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Speaker 1: Can I just beque? Like, if I had to pick

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Speaker 1: a character from the next generation, I would pick Q.

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Speaker 2: Really not Data. Data might be the smartest one.

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Speaker 1: A smart than Q can do anything in time and space.

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Speaker 2: Q has no rules, so it doesn't really count exactly exactly,

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Speaker 2: So you basically you want to be God, you're.

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Speaker 1: Saying, I mean, who doesn't, come on, Q.

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Speaker 2: Has so much responsibility. Every child who's dying of cancer.

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Speaker 2: That's Q's fault, is it?

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Speaker 1: Is it?

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Speaker 2: Really? If you had the power to save a child

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Speaker 2: and you didn't, then yeah, I think you're kind of responsible. Boy.

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Speaker 1: That's a lot of gud killed.

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Speaker 2: That's why I'd rather be data.

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Speaker 1: Do you want to be data or be data?

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Speaker 2: Hmm, Yeah, that's a good question. I actually just want

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Speaker 2: to harness data's computing powers to solve mysteries of the universe. Yeah.

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Speaker 1: That's a lot of makeup to put on every data.

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Speaker 2: It's pretty heavy.

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Speaker 1: Yeah, but anyways, welcome to our podcast. We also like

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Speaker 1: to answer questions, not just talk about the answers that

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Speaker 1: physicists have found. We also like to think about questions

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Speaker 1: about the universe.

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Speaker 2: Because everybody's got questions. I've got questions, You've got questions.

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Speaker 2: Everybody who looks up at the night sky and wonders

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Speaker 2: how it all works, or stares down between their toes

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Speaker 2: and wants to understand the tiniest particles is yearning to

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Speaker 2: understand how the world works, and that means asking questions.

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Speaker 2: And on this podcast we answer questions at the edge

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Speaker 2: of knowledge, those pose by physicists and those pose by listeners.

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Speaker 2: So if you have questions about the nature of the

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Speaker 2: universe or some explanation you've heard somewhere that didn't quite

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Speaker 2: make sense to you, write to us to questions at

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Speaker 2: Danielandjorge dot com. We really do. Right back to all

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Speaker 2: of our listeners.

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Speaker 1: Yeah, we're all curious about how the universe works, why

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Speaker 1: we're in it, and how it's all put together. Although

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Speaker 1: I'm not exactly curious about the particles in your toes

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Speaker 1: or anyone's toes. Maybe we'll leave that part out of

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Speaker 1: our questions.

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Speaker 2: Wow, limits to your curiosity. That's disappointing.

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Speaker 1: Yeah, I think there should be limits to anyone's curiosity.

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Speaker 1: But yeah, we like to answer questions here on the

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Speaker 1: podcast and plans from listeners, and so thanks to everyone

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Speaker 1: who sent their questions in.

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Speaker 2: Often I'll just write back, but sometimes we choose questions

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Speaker 2: to answer on the podcast because we think lots of

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Speaker 2: people will want to hear the answers.

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Speaker 1: And so today on the podcast, we'll be tackling listener

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Speaker 1: questions number forty nine. What are we gonna do when

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Speaker 1: we hit fifty, Daniel, We're gonna have a mid podcast

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Speaker 1: live crisis.

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Speaker 2: We're gonna have a nice cake with fifty on it,

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Speaker 2: and we're gonna fall asleep before the end of the.

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Speaker 1: Party and then burn your house down.

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Speaker 2: What it's gonna be virtual, of course, but.

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Speaker 1: Yeah, we're answering listener questions here today and we have

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Speaker 1: some awesome questions here from our listeners. There's one about

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Speaker 1: black hole identity, there's one about neutrino and how many

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Speaker 1: there are in the universe. And we also have a

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Speaker 1: question about what it's like to serve a gravitational wave

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Speaker 1: and what happens when you wipe out, Like where do

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Speaker 1: you fall if it's a gravitational wave? But let's jump

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Speaker 1: right in. Our first question comes from Matthew, who comes

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Speaker 1: from Barry, Ontario.

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Speaker 4: Hello, Daniel and Jorge. This is Matthew from Barry, Ontario

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Speaker 4: up here in Canada, and like many of your listeners,

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Speaker 4: I spend a bit of time thinking.

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Speaker 1: About black holes.

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Speaker 4: While I understand that it is impossible for us to

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Speaker 4: see what lurks beyond the event horizon, I was curious

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Speaker 4: if there is consensus in the scientific community about all

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Speaker 4: black holes being the same, or if they could vary

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Speaker 4: inside based on their density. For example, could a smaller

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Speaker 4: black hole be not a black hole at all, but

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Speaker 4: a dark star, while the super massive black holes at

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Speaker 4: the center of some galaxies be a more traditional black

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Speaker 4: hole or a string theory fuzz. Thank you very much

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Speaker 4: for the wonderful show and I look forward to hearing

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Speaker 4: your response.

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Speaker 1: All right, I feel like this question ken has an

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Speaker 1: identity problem in itself.

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Speaker 2: It's so many questions but also one.

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Speaker 1: But I think Matthew's basic question is about the identity

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Speaker 1: of black holes, Like, are all black holes the same?

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Speaker 1: Are they actually black holes? Could they be something else?

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Speaker 1: Is it a case of mistaken identity? Or do all

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Speaker 1: black holes come with an ID tag?

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Speaker 2: Yeah, he's basically wondering what's going on inside black holes

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Speaker 2: and if they all have to be the same on

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Speaker 2: the inside, and whether the things we've seen out there

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Speaker 2: in the universe that look like black holes could actually

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Speaker 2: be a bunch of different kinds of stuff that all

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Speaker 2: mimic black holes. So it's a really cool question guess

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Speaker 2: at the heart of what we think is going on

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Speaker 2: inside black holes.

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Speaker 1: M Like, maybe what we call black holes are actually

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Speaker 1: maybe a varity of different things.

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Speaker 2: Yeah, it's possible. And two black holes with the same mass,

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Speaker 2: do they have to look the same on the inside?

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Speaker 1: Wait on how much mass is in it? Or Like,

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Speaker 1: two things that look like black holes, are they actually

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Speaker 1: black holes? Or do you think he's asking if they're

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Speaker 1: the same, if there's any property that sets them apart?

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Speaker 2: Yeah, I think he's asking both of those questions, and

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Speaker 2: I think we should start with that. Like, if you

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Speaker 2: have two black holes that have the same mass, are

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Speaker 2: they the same thing? Are they indistinguishable? Or are they different?

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Speaker 2: And this is a big question in general, relativity goes

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Speaker 2: by the name of two black holes have hair? Essentially,

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Speaker 2: are there texture or details? Are there tiny little properties

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Speaker 2: that set two black holes apart the way two Like

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Speaker 2: identical twins are always a little bit different. Are two

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Speaker 2: black holes with the same mass, could they actually be

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Speaker 2: a little bit different on the inside.

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Speaker 1: Well, I feel there's two questions. One is like are

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Speaker 1: they the same? And can you tell if they're the same?

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Speaker 1: Aren't those two separate questions?

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Speaker 2: Yeah, those are two separate questions. So as you can see,

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Speaker 2: with black holes, we have like a constantly multiplying stream

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Speaker 2: of questions.

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Speaker 1: It's like a black hole of questions. It's a bit

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Speaker 1: of a rabbit hole. It's a black rabbit hole. So

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Speaker 1: which which question are we tackling? Can you tell if

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Speaker 1: two black holes are different or whether they're actually different inside?

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Speaker 2: Yeah, we can talk about all of it, but let's

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Speaker 2: start with what's going on inside black holes, at least

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Speaker 2: what we think is going on.

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Speaker 1: Okay, well, you sort of mentioned the no hair problem,

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Speaker 1: and that one's more of a like can you tell

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Speaker 1: if two black holes are different problem?

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Speaker 2: I think it also touches on whether the black holes

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Speaker 2: inherently are different. Are there features to two black holes

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Speaker 2: which tell them apart? Because in general relativity, the idea

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Speaker 2: is that all you can know about a black hole

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Speaker 2: are three different quantities how much mass it has, whether

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Speaker 2: it's spinning, and whether it has electrical charge. And to

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Speaker 2: say that that's all you can know about a black

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Speaker 2: hole means that that's what defines a black hole. So

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Speaker 2: in general relativity, two black holes with the same mass, spin,

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Speaker 2: and charge really are identical according to that theory.

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Speaker 1: From the outside right, I mean, it's basically saying that's

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Speaker 1: all you can tell about what's inside a black hole.

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Speaker 2: It means those are the only properties of the objects,

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Speaker 2: So even on the inside, they would be identical again

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Speaker 2: according to general relativity. Important caveat we can get to later.

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Speaker 1: But I guess, how can they be exactly identical or

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Speaker 1: how can we know or how can the theory know

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Speaker 1: that it's identical because inside the black hole maybe things

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Speaker 1: are arranged differently.

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Speaker 2: We can't know currently because we can't see inside black holes,

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Speaker 2: but that doesn't stop the theory from predicting what's there

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Speaker 2: and describing what we think is happening. And according to

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Speaker 2: general relativity, again big caveat there we can get to

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Speaker 2: in a minute. All these black holes, if they have

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Speaker 2: the same mass, spin, in charge, really are identical. They

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Speaker 2: have the same exact internal structure because they're defined just

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Speaker 2: by those three numbers, So there's no whiggle room. There's

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Speaker 2: no opportunity for a black hole made of bananas to

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Speaker 2: be different from a black hole made of bowling balls

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Speaker 2: or squirrels if they have the same mass, spin, and charge.

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Speaker 2: That's again according to general relativity, which is predict what's

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Speaker 2: inside black holes, though it's not something we've seen.

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Speaker 1: I guess what I mean is like a black hole

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Speaker 1: is like a sphere right like to us, it has volume,

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Speaker 1: and so what does general relativity predict is inside of

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Speaker 1: that sphere just a singularity? Like everything just collapses instantly

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Speaker 1: or what.

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Speaker 2: Well, a black hole that's had time to settle, everything

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Speaker 2: will fall towards the singularity. So if things are still

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Speaker 2: dynamically falling into a black hole, its state is changing.

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Speaker 2: But after a long time. When it settles, then it's

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Speaker 2: just defined by these three numbers. And yeah, two black

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Speaker 2: holes with the same mass will each have a singularity

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Speaker 2: inside them with the same.

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Speaker 1: Mass and nothing between the singularity and the event horizon.

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Speaker 1: What does general relativity say is between the singularity which

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Speaker 1: is at the center, and the event horizon, which is

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Speaker 1: the outer shell of the black hole.

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Speaker 2: So it depends a little bit on the mass, spin,

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Speaker 2: in charge. These kinds of black holes have different internal structures,

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Speaker 2: like the simplest kind one with just mass and no spin,

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Speaker 2: no charge, or this is the kind most people talk

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Speaker 2: about and think about, is just a sphere and in

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Speaker 2: the inside you have the singularity and there's nothing else.

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Speaker 2: If it's charged or if it's spinning, then the structure

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Speaker 2: in the inside is a little bit different, Like you

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Speaker 2: don't actually have a singularity if it's spinning, you have

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Speaker 2: a ringularity because you need an object that can spin

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Speaker 2: and singularities can't. And you can have different kinds of

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Speaker 2: horizons inside the black hole or even near the black

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Speaker 2: hole on the outside if it's spinning and if it

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Speaker 2: has charge.

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Speaker 1: Well, that's an interesting concept you just mentioned, which is

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Speaker 1: like the settling of a black hole. Now does that

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Speaker 1: happen like instantly over billions of years trillions? Does it

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Speaker 1: ever happen? Doesn't times stop? Inside of a black hole?

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Speaker 2: Nothing happens instantly, right. Relativity describes how there's a maximum

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Speaker 2: speed limit to the universe, and so you definitely can't

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Speaker 2: have things instantly collapsing into a singularity. It always takes time.

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Speaker 2: How much time it takes depends on who you are

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Speaker 2: and where you are. Like, if you're outside the black

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Speaker 2: hole and you're watching things fall in, you'll actually not

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Speaker 2: see them fall in because time slows down so much

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Speaker 2: at the event horizon. You'll see them frozen at the

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Speaker 2: event horizon. If you are riding that banana into the

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Speaker 2: black hole, then you will see yourself past the event

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Speaker 2: horizon and you'll fall in, and you'll reach the singularity

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Speaker 2: in a finite amount of time. So how long it

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Speaker 2: takes depends on the observer. In general relativity, these things

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Speaker 2: are very screwy.

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Speaker 1: But I guess maybe then the scenario I wonder that

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Speaker 1: Matthew's thinking about me, Like, if I have two black holes,

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Speaker 1: they have the same mass and energy and spin in

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Speaker 1: charge and all that they're identical, But then black hole

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Speaker 1: A eats a banana, and black hole b eats a

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Speaker 1: bowling ball. Like to us, it takes some time for

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Speaker 1: the banana to and bolling bull to make it to

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Speaker 1: the center of the black hole. So are those two

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Speaker 1: black holes different in the meantime.

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Speaker 2: In the meantime they are. Yeah, But if the bowling

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Speaker 2: ball and the banana have the same mass, and like

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Speaker 2: that's a tiny bowling ball or a huge banana, then

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Speaker 2: eventually they do reach steady state, which is just described

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Speaker 2: by the mass, spin and charge.

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Speaker 1: But could we tell that one aid the banana and

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Speaker 1: the other one ate the bowling ball.

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Speaker 2: We couldn't, right, Not after they've settled into the singularity exactly.

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Speaker 2: According to general relativity, that information is lost. Before that

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Speaker 2: information is still within the event horizon. We can't see it,

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Speaker 2: but it does still exist within the black hole after

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Speaker 2: it's settled into the singularity. According to general relativity, that

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Speaker 2: information is gone because the state is perfectly described by

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Speaker 2: the mass, spin in charge.

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Speaker 4: Mmm.

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Speaker 1: So then it's sort of possible for two black holes

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Speaker 1: to be different, perhaps, but for us to not be

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Speaker 1: able to tell them apart.

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Speaker 2: Yeah, that is possible, and that's a transient state.

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Speaker 1: Right, Well, black holes are eating all the time, right,

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Speaker 1: So black.

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Speaker 2: Holes in the real world yet are always eating are

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Speaker 2: They're always surrounded by something. There's never a true vacuum.

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Speaker 2: There's always a solar wind or particles everywhere. So yeah, absolutely,

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Speaker 2: black holes are always eating in real life. In the

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Speaker 2: sort of thought experiments we construct, you could imagine a

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Speaker 2: black hole surrounded by actually nothing and then you just

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Speaker 2: drop a banana into it. But yeah, and the real universe,

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Speaker 2: black holes are never surrounded by nothing.

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Speaker 1: But I think, as you were saying, this all depends

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Speaker 1: on general relativity.

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Speaker 2: Yeah, exactly. This is a picture from classical physics that

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Speaker 2: says that singularities can exist within black holes, and that

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Speaker 2: it matter could be compressed into a tiny dot. That's

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Speaker 2: totally incompatible with what we know about the nature of

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Speaker 2: reality that is quantum mechanical. Though, when things get really

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Speaker 2: really small, like the size of singularities, different rules take

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Speaker 2: over and have to be accounted for, rules that general

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Speaker 2: relativity ignores. So we don't think singularities actually do exist

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Speaker 2: at the heart of any black holes in our universe.

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Speaker 2: We think, if black holes are even real, that there's

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Speaker 2: some other kind of thing going on, something dictated by

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Speaker 2: a different theory of physics, not general relativity, one that

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Speaker 2: correctly incorporates the quantum nature of our universe, a theory

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Speaker 2: we don't have today, so we can't say what we

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Speaker 2: actually think is inside a black hole.

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Speaker 1: I think maybe Matthew's question is, like, let's say black

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Speaker 1: holes they're all a little bit different inside, depending on

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Speaker 1: their density, Like maybe some of them are super dense

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Speaker 1: but collass into a singularity, or maybe some do, or

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Speaker 1: maybe some are more like uh, let strings every fuzzballs.

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Speaker 1: I wonder if they can be different in that way inside,

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Speaker 1: but to us from the outside they all look the same.

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Speaker 2: It's possible, and it depends on your flavor of quantum gravity.

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Speaker 2: If what he's describing is true. There are no classical

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Speaker 2: black holes in the universe. They're all some weird quantum version.

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Speaker 2: And you're right, there could be a variety, right, There

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Speaker 2: could be some fuzzballs and some dark stars and some

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Speaker 2: white holes and some other kind of crazy stuff going on.

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Speaker 2: And whether we could see the difference on the outside

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Speaker 2: also depends on the details of the quantum gravity theory.

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Speaker 2: In some scenarios, you can tell what's inside a black

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Speaker 2: hole by studying the patterns of the hawking radiation, which

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Speaker 2: might be quantum entangled with the details of what's going

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Speaker 2: on inside and leaking that information out. There are other

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Speaker 2: quantum theories of black holes in which you still can't

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Speaker 2: get that information out even though it is inside the

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Speaker 2: event horizon. So it depends on your flavor of quantum

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Speaker 2: black hole. But it's possible that all these things do

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Speaker 2: really exist in our universe.

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Speaker 1: Hmmm. It sounds like it sort of depends on what

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Speaker 1: you define as a black hole, right, Like, if you

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Speaker 1: define it as what a general what relativity calls a

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Speaker 1: black hole, then you get one as er. But if

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Speaker 1: you just define it as something that has an event

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Speaker 1: horizon that doesn't let you look inside, it is possible

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Speaker 1: maybe to have different kinds of black holes exactly.

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Speaker 2: And remember, not all of these objects even have event horizons.

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Speaker 2: When we talk about a black hole, we sort of

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Speaker 2: imply an event horizon. But it's possible that some of

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Speaker 2: the things out there in the universe that we call

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Speaker 2: black holes don't actually have event horizons. We haven't verified

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Speaker 2: the event horizon nature of those objects. They're just really

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Speaker 2: really small, really really massive, and really really space bendy

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Speaker 2: in the way we expect black holes to be, but

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Speaker 2: we haven't like zoomed up close and proven that they

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Speaker 2: actually have event horizons. And some of these theories don't

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Speaker 2: create objects with event horizons.

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Speaker 1: But some do, right, Like you could have a dark

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Speaker 1: star that does have event horizon.

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Speaker 2: Perhaps, yeah, some of them do. It depends on the

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Speaker 2: flavor or quantum gravity.

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Speaker 1: Hmm, all right, well then so then the answer for

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Speaker 1: Matthew is, uh, it depends and we don't.

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Speaker 2: Know that summarizes most of physics.

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Speaker 1: Yes, it depends that black hole that's in your backyard.

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Speaker 2: What it means is that there's still so much to

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Speaker 2: learn about the nature of these objects. And the answer

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Speaker 2: to the question might not be it's this kind or

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Speaker 2: it's that kind, but it's all the kinds. I love

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Speaker 2: that possibility.

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Speaker 1: Mmm. So it sort of maybe depends on what's actually

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Speaker 1: going on, which we don't have a clear theory about.

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Speaker 2: And we might not ever know.

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Speaker 1: Ever.

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Speaker 2: It might be that the universe prevents us from ever

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Speaker 2: seeing inside these black holes, or that the information in

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Speaker 2: the Hawking radiation doesn't reveal what's inside them. It might

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Speaker 2: be that we're not smart enough to figure out the universe.

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Speaker 1: Who knows, Boy, I wish you had left the question

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Speaker 1: on a more positive note, But it could.

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Speaker 2: Be that we figure it all out and then you

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Speaker 2: go in ten generations the latest. Daniel and Jorge are

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Speaker 2: explaining it all to you on their podcast.

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Speaker 1: All right, all right, yeah, that's good. That doesn't leave

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Speaker 1: us in a black hole. All right, let's tackle some

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Speaker 1: of our other questions. We have questions here about the

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Speaker 1: number of neutrinas in the universe and also about what

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Speaker 1: it's like to bob up and down on a gravitation wave.

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Speaker 1: So let's stick into those. But first let's take a

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Speaker 1: quick break. Right we're answering questions from listeners, and our

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Speaker 1: next question comes from Sam from British Columbia.

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Speaker 3: Hello, Daniel and Jorge, this is Sam from British Columbia

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Speaker 3: and thank you for your podcasts and availability to answer

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Speaker 3: our questions. It is really appreciated about neutrinos. You always

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Speaker 3: mention how many trillions are passing through the Earth every second.

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Speaker 3: This got me wondering about how many neutrinos are estimated

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Speaker 3: to exist in the universe, as well as proportions for

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Speaker 3: the other main particle groups.

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Speaker 2: In the standard model.

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Speaker 3: It has often estimated that there are ten to the

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Speaker 3: eighty particles in the universe. When he asked chat gpt

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Speaker 3: for help, I got back that each of the groups

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Speaker 3: of leptons, quarks, and bow sounds each were in the

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Speaker 3: order of ten to the eighty, and then that there

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Speaker 3: were significantly more electrons than neutrinos, and also that there

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Speaker 3: were about ten to the eighty of each. I think

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Speaker 3: chat gpt once again was confused, and I'm hoping you

442
00:21:38,440 --> 00:21:39,919
Speaker 3: can help unconfuse me.

443
00:21:40,400 --> 00:21:43,639
Speaker 1: Thanks all right, Well, I'm glad that we were his

444
00:21:43,720 --> 00:21:46,000
Speaker 1: second choice for answering questions about the universe.

445
00:21:48,240 --> 00:21:50,120
Speaker 2: Oh man, chat GPT.

446
00:21:51,200 --> 00:21:55,280
Speaker 1: I guess chat gpt is free. I guess you don't

447
00:21:55,320 --> 00:21:57,720
Speaker 1: have to listen to ads d I.

448
00:21:57,680 --> 00:21:59,879
Speaker 2: Think you have to pay for some version of chat GPT.

449
00:22:00,560 --> 00:22:02,840
Speaker 2: No version of it can be relied on to answer

450
00:22:02,920 --> 00:22:05,880
Speaker 2: physics questions. I see, well, you know what they say,

451
00:22:06,040 --> 00:22:08,360
Speaker 2: you get what you pay for. You can do get

452
00:22:08,400 --> 00:22:09,000
Speaker 2: what you paid for.

453
00:22:09,840 --> 00:22:12,600
Speaker 1: It sounds like chat jipt did not answer Sam's question

454
00:22:12,720 --> 00:22:15,040
Speaker 1: or game of an answer that maybe it was confusing.

455
00:22:15,600 --> 00:22:19,000
Speaker 2: Well, it's also not designed to answer physics questions. It's

456
00:22:19,080 --> 00:22:21,919
Speaker 2: designed to generate text which looks like the answers to

457
00:22:22,000 --> 00:22:24,760
Speaker 2: questions it's not designed to do any reasoning, or have

458
00:22:24,800 --> 00:22:28,280
Speaker 2: a model of the universe, or actually think in any way,

459
00:22:28,600 --> 00:22:31,480
Speaker 2: or be accurate or explain things. So I wouldn't rely

460
00:22:31,560 --> 00:22:35,120
Speaker 2: on chat gpt to answer any questions. Yet you could

461
00:22:35,119 --> 00:22:39,520
Speaker 2: say that about anything. Man, your toaster hasn't replaced you yet.

462
00:22:39,840 --> 00:22:42,240
Speaker 1: Well, you know, it's like they say, chat chipet is

463
00:22:42,280 --> 00:22:44,280
Speaker 1: not designed to do basic math, right, Like, if you

464
00:22:44,280 --> 00:22:45,960
Speaker 1: ask it a math question, it may not give you

465
00:22:46,040 --> 00:22:48,720
Speaker 1: the right answer. But I've seen examples of like asking

466
00:22:48,800 --> 00:22:52,320
Speaker 1: Chad Gipt to check using some sort of math toolbox,

467
00:22:52,359 --> 00:22:53,639
Speaker 1: and then it gives you the right answer.

468
00:22:53,760 --> 00:22:55,760
Speaker 2: Yeah, you know a stop clock is right a few

469
00:22:55,800 --> 00:22:57,080
Speaker 2: times a day, right, yeah?

470
00:22:57,119 --> 00:22:59,840
Speaker 1: Yeah, So you could ask chat gipt twice a day

471
00:23:00,840 --> 00:23:03,560
Speaker 1: to go read every physics paper in the universe and

472
00:23:03,600 --> 00:23:05,119
Speaker 1: then come back to you with an answer, which is

473
00:23:05,160 --> 00:23:07,480
Speaker 1: basically what we do in this podcast.

474
00:23:07,680 --> 00:23:09,719
Speaker 2: And it's the wrong tool for the job. You know.

475
00:23:09,800 --> 00:23:13,240
Speaker 2: Its job is to generate text which resembles answers, not

476
00:23:13,640 --> 00:23:17,320
Speaker 2: to reason and think and provide explanations. I don't think

477
00:23:17,320 --> 00:23:19,520
Speaker 2: it'll ever be a good place to ask physics questions.

478
00:23:19,640 --> 00:23:22,280
Speaker 2: I say, I see somedays somebody might actually develop an

479
00:23:22,280 --> 00:23:25,240
Speaker 2: AI which is good at the reasoning and thinking and explaining.

480
00:23:25,560 --> 00:23:27,480
Speaker 2: I'm not ruling that out. I'm pretty sure that will

481
00:23:27,520 --> 00:23:30,720
Speaker 2: happen one day, but large language models won't get there.

482
00:23:32,119 --> 00:23:34,360
Speaker 1: I think what you're saying is that we're the right tools.

483
00:23:34,720 --> 00:23:41,000
Speaker 2: Yes, ask us where we were, just the pair tools,

484
00:23:41,040 --> 00:23:42,280
Speaker 2: just like data on Star Trek.

485
00:23:42,359 --> 00:23:45,120
Speaker 1: Right, there you go, There you go. Maybe the next

486
00:23:45,200 --> 00:23:48,760
Speaker 1: chat GBT should be called Daniel and Cordy Chat DJ.

487
00:23:49,040 --> 00:23:51,560
Speaker 1: All right, well, let's get to Sam's question here. Samon

488
00:23:51,560 --> 00:23:56,040
Speaker 1: wants to know how many neutrinias there are in the universe, right, Like,

489
00:23:56,080 --> 00:23:58,600
Speaker 1: what's a good estimate for the number of neutrinos in

490
00:23:58,640 --> 00:23:59,200
Speaker 1: the universe?

491
00:23:59,640 --> 00:24:03,720
Speaker 2: Such an awesome question because there are so many neutrinos

492
00:24:03,760 --> 00:24:05,440
Speaker 2: in the universe, it's mind boggling.

493
00:24:06,000 --> 00:24:08,119
Speaker 1: Well, there's a lot of everything in the universe, right, Well,

494
00:24:08,119 --> 00:24:10,240
Speaker 1: there's only one me and one you. How do you know.

495
00:24:12,920 --> 00:24:15,480
Speaker 2: Ship a theseus man, if there's another copy of me,

496
00:24:15,560 --> 00:24:16,119
Speaker 2: it's not me.

497
00:24:18,240 --> 00:24:21,160
Speaker 1: Well, there could be one you that has gone through

498
00:24:21,200 --> 00:24:24,640
Speaker 1: the same experiences as you. Wouldn't that be the same Anyways,

499
00:24:24,840 --> 00:24:28,600
Speaker 1: let's get back on track here. It's a big universe.

500
00:24:28,840 --> 00:24:30,879
Speaker 1: Asne wants to know how many neutrinios are Why do

501
00:24:30,880 --> 00:24:32,800
Speaker 1: you think he wants to know how many there are? Like,

502
00:24:32,840 --> 00:24:36,160
Speaker 1: why neutrinos? Why not how many electrons or quarks there

503
00:24:36,160 --> 00:24:36,960
Speaker 1: are in the universe?

504
00:24:37,160 --> 00:24:40,000
Speaker 2: I think because neutrinos give us a window into a

505
00:24:40,040 --> 00:24:43,679
Speaker 2: deeper understanding of what's out there in the universe. Like

506
00:24:43,760 --> 00:24:46,960
Speaker 2: we're made out of quarks and electrons, and that feels like, Oh,

507
00:24:46,960 --> 00:24:49,520
Speaker 2: that's the universe, what's all that made out of? But

508
00:24:49,640 --> 00:24:52,280
Speaker 2: as soon as you realize that our senses are limited

509
00:24:52,680 --> 00:24:54,639
Speaker 2: and that there's so much more going on in the

510
00:24:54,760 --> 00:24:57,159
Speaker 2: universe than the little bits of matter that you and

511
00:24:57,240 --> 00:24:59,520
Speaker 2: I are made out of, it makes you wonder what's

512
00:24:59,520 --> 00:25:01,600
Speaker 2: out there, how much of it is there? And new

513
00:25:01,640 --> 00:25:04,800
Speaker 2: trinos are like the tip of that invisible matter Iceberg.

514
00:25:05,480 --> 00:25:08,399
Speaker 1: I see, Well, how would you answer the question of

515
00:25:08,440 --> 00:25:09,760
Speaker 1: how many new trinos there are?

516
00:25:10,000 --> 00:25:12,560
Speaker 2: Yeah, so it takes a few steps. Basically, you have

517
00:25:12,600 --> 00:25:14,720
Speaker 2: to know how many protons there are in the universe,

518
00:25:15,000 --> 00:25:16,600
Speaker 2: and then you have to try to figure out how

519
00:25:16,640 --> 00:25:20,080
Speaker 2: many neutrinos there are per proton. And it turns out

520
00:25:20,080 --> 00:25:21,920
Speaker 2: that we can do both of those calculations.

521
00:25:21,960 --> 00:25:24,520
Speaker 1: Wait, why do we have to go through protons?

522
00:25:24,600 --> 00:25:26,520
Speaker 2: Because the way we figure out how many new trinos

523
00:25:26,560 --> 00:25:28,639
Speaker 2: there are in the universe is by going back to

524
00:25:28,680 --> 00:25:32,439
Speaker 2: the very very early universe and understanding how photons and

525
00:25:32,520 --> 00:25:36,080
Speaker 2: protons and neutrinos and dark matter all slashed around and

526
00:25:36,119 --> 00:25:39,040
Speaker 2: pushed against each other. It's this plasma soup at the

527
00:25:39,080 --> 00:25:41,320
Speaker 2: very beginning of the universe that reveals the answers to

528
00:25:41,440 --> 00:25:45,720
Speaker 2: all of these questions. From measurements of the cosmic microwave background,

529
00:25:45,880 --> 00:25:48,280
Speaker 2: we can learn a lot about that plasma and how

530
00:25:48,320 --> 00:25:50,600
Speaker 2: it was slashing, and it tells us the answers to

531
00:25:50,640 --> 00:25:53,199
Speaker 2: all of these things. Then, specific ways it tells us

532
00:25:53,240 --> 00:25:56,040
Speaker 2: some ratios allow us to get to these answers.

533
00:25:56,720 --> 00:25:59,200
Speaker 1: Like the beginning of the universe tells you the original

534
00:25:59,280 --> 00:26:00,840
Speaker 1: recipe of the universe kind.

535
00:26:00,720 --> 00:26:03,159
Speaker 2: Of yeah, exactly, And some of that hasn't changed, and

536
00:26:03,200 --> 00:26:05,280
Speaker 2: some of that has changed, and we know how that

537
00:26:05,359 --> 00:26:07,879
Speaker 2: has changed, and we can evolve that through time. But

538
00:26:07,920 --> 00:26:11,120
Speaker 2: it basically starts the machine and tells us how things

539
00:26:11,160 --> 00:26:12,040
Speaker 2: evolve through time.

540
00:26:12,240 --> 00:26:14,560
Speaker 1: But is it even possible to get this answer because

541
00:26:14,600 --> 00:26:17,679
Speaker 1: aren't neutrino's being created, for example, all the time in

542
00:26:17,720 --> 00:26:21,359
Speaker 1: the sun? Like, are new neutrinos being made all the time?

543
00:26:21,560 --> 00:26:25,840
Speaker 2: Yeah? The specific number like to the individual neutrino is

544
00:26:25,880 --> 00:26:29,000
Speaker 2: not very well defined because neutrinos are quantum particles, and

545
00:26:29,040 --> 00:26:32,159
Speaker 2: so they even have probabilities of existing. Like you have

546
00:26:32,160 --> 00:26:35,920
Speaker 2: a certain reaction that might generate neutrinos. Whether it actually

547
00:26:36,000 --> 00:26:38,919
Speaker 2: did or not isn't even determined until it interacts with

548
00:26:38,960 --> 00:26:42,280
Speaker 2: some classical objects. So from a quantum mechanical point of view,

549
00:26:42,440 --> 00:26:45,239
Speaker 2: getting the answer down to like the individual neutrino is

550
00:26:45,280 --> 00:26:48,239
Speaker 2: not technically possible, and even zooming out a little bit

551
00:26:48,280 --> 00:26:50,800
Speaker 2: as you say, there are neutrino factories in the universe

552
00:26:50,840 --> 00:26:54,840
Speaker 2: and neutrinos being annihilated. Neutrinos can be created and destroyed,

553
00:26:55,160 --> 00:26:57,840
Speaker 2: so the number is changing. But it turns out that

554
00:26:57,880 --> 00:27:00,480
Speaker 2: the number of neutrinos being created in roid in the

555
00:27:00,560 --> 00:27:04,520
Speaker 2: universe is really tiny compared to like the huge reservoir

556
00:27:04,560 --> 00:27:05,960
Speaker 2: of neutrinos we already have.

557
00:27:06,359 --> 00:27:07,240
Speaker 1: Well, how do you.

558
00:27:07,200 --> 00:27:09,880
Speaker 2: Know, because we think we understand those processes, and we've

559
00:27:09,960 --> 00:27:12,760
Speaker 2: measured neutrinos that come from space and neutrinos that pass

560
00:27:12,800 --> 00:27:15,920
Speaker 2: through the Earth. Neutrino physics is something we're really starting

561
00:27:15,960 --> 00:27:18,119
Speaker 2: to get a grip on in like the last twenty years.

562
00:27:18,119 --> 00:27:21,000
Speaker 2: So we are a pretty good handle on how many

563
00:27:21,040 --> 00:27:23,119
Speaker 2: neutrinos are out there and how many are being made

564
00:27:23,119 --> 00:27:26,640
Speaker 2: by the Sun. We even see neutrinos generated by crazy

565
00:27:26,680 --> 00:27:31,680
Speaker 2: sources in other galaxies. Neutrino astronomy is something that's really

566
00:27:31,680 --> 00:27:33,720
Speaker 2: come into its own in the last couple of decades.

567
00:27:34,359 --> 00:27:36,760
Speaker 1: And so what's the picture. It's like the Sun is

568
00:27:36,760 --> 00:27:40,200
Speaker 1: making bazillions of neutrinos, but that's very like a drip

569
00:27:40,240 --> 00:27:42,639
Speaker 1: of water compared to like we're swimming in an ocean

570
00:27:42,680 --> 00:27:43,359
Speaker 1: of neutrinos.

571
00:27:43,480 --> 00:27:45,800
Speaker 2: Zechon what you're saying exactly. It's like asking what's the

572
00:27:45,840 --> 00:27:47,879
Speaker 2: volume of the Pacific? Well, you don't really have to

573
00:27:47,920 --> 00:27:51,000
Speaker 2: worry about evaporation and rain because those are tiny details

574
00:27:51,520 --> 00:27:53,960
Speaker 2: relative to massive volume of water there.

575
00:27:54,720 --> 00:27:57,159
Speaker 1: And so then what's the connection to protons? Why do

576
00:27:57,200 --> 00:27:59,359
Speaker 1: we need to know how many protons there are?

577
00:28:00,160 --> 00:28:03,000
Speaker 2: Know how many neutrinos there are per proton. That's a

578
00:28:03,000 --> 00:28:05,760
Speaker 2: measurement we can make back in the very early universe.

579
00:28:06,359 --> 00:28:08,520
Speaker 2: If you wind the universe backwards, we see that it

580
00:28:08,560 --> 00:28:11,679
Speaker 2: gets hotter and denser. Right now, the universe is kind

581
00:28:11,720 --> 00:28:15,800
Speaker 2: of old and cold, very dilute, very chill. But as

582
00:28:15,800 --> 00:28:18,600
Speaker 2: you wind time backwards and you undo the expansion, things

583
00:28:18,640 --> 00:28:21,280
Speaker 2: get very hot and very dense. Back to some early

584
00:28:21,359 --> 00:28:24,159
Speaker 2: state where there were protons and there were photons, and

585
00:28:24,200 --> 00:28:27,760
Speaker 2: there were electrons, and there were also neutrinos zipping about,

586
00:28:27,960 --> 00:28:30,320
Speaker 2: and we can see photons from that moment. This is

587
00:28:30,359 --> 00:28:33,280
Speaker 2: the moment we call the surface of last scattering, when

588
00:28:33,320 --> 00:28:36,680
Speaker 2: the universe became transparent to those photons, so they're still around.

589
00:28:37,080 --> 00:28:39,600
Speaker 2: So we can see a picture of what that early

590
00:28:39,680 --> 00:28:43,520
Speaker 2: universe plasma looked like. It's called the cosmic microwave background radiation,

591
00:28:43,920 --> 00:28:46,120
Speaker 2: and we can see patterns in it. We see wiggles

592
00:28:46,120 --> 00:28:49,240
Speaker 2: and we see waves. Those wiggles and waves are determined

593
00:28:49,280 --> 00:28:52,600
Speaker 2: by how it's slashing, which depends on how many protons

594
00:28:52,600 --> 00:28:55,400
Speaker 2: there are, how many photons there are, how much dark

595
00:28:55,480 --> 00:28:58,680
Speaker 2: matter there is. As you change those fractions, that early

596
00:28:58,760 --> 00:29:03,360
Speaker 2: universe plasma slashed differently because those different pieces all behave differently.

597
00:29:03,600 --> 00:29:06,560
Speaker 1: But even neutrinos were consequential at the beginning of the

598
00:29:06,600 --> 00:29:10,680
Speaker 1: universe because I thought neutrinos were basically massless and they're

599
00:29:10,720 --> 00:29:14,240
Speaker 1: ghostly and they they don't really interact with anything much.

600
00:29:14,960 --> 00:29:18,400
Speaker 1: Isn't there like a wide range of neutrino proportions that

601
00:29:18,480 --> 00:29:20,160
Speaker 1: could have been there at the beginning of the universe.

602
00:29:20,360 --> 00:29:23,720
Speaker 2: Yeah. Absolutely. Neutrinos don't interact very much, but they do

603
00:29:23,760 --> 00:29:26,880
Speaker 2: have energy, and so they affect the energy density of

604
00:29:26,920 --> 00:29:30,760
Speaker 2: the universe, which changes its expansion. And because neutrinos are

605
00:29:30,840 --> 00:29:32,680
Speaker 2: very very light, they sort of fall into the same

606
00:29:32,800 --> 00:29:36,640
Speaker 2: category as photons. Back in the early universe, everything that

607
00:29:36,720 --> 00:29:38,880
Speaker 2: was moving almost at the speed of light or at

608
00:29:38,880 --> 00:29:41,680
Speaker 2: the speed of light gets counted kind of as radiation.

609
00:29:42,120 --> 00:29:45,040
Speaker 2: Remember we talked about this once, and stuff that's moving

610
00:29:45,120 --> 00:29:48,560
Speaker 2: very very slowly gets counted as matter. And so things

611
00:29:48,560 --> 00:29:51,840
Speaker 2: that are moving as radiation do affect the expansion of

612
00:29:51,880 --> 00:29:54,360
Speaker 2: the universe because they affect the energy density in this

613
00:29:54,480 --> 00:29:57,800
Speaker 2: complicated way. So you're right, the neutrinos are weak, but

614
00:29:57,880 --> 00:30:00,360
Speaker 2: they still have energy and that affects the old overall

615
00:30:00,400 --> 00:30:03,360
Speaker 2: balancing of these equations in general relativity.

616
00:30:03,280 --> 00:30:04,840
Speaker 1: There's stills a piece of the pot.

617
00:30:05,000 --> 00:30:08,000
Speaker 2: Yeah, exactly. And it turns out there's a huge number

618
00:30:08,000 --> 00:30:10,200
Speaker 2: of them, so they have a pretty big influence.

619
00:30:10,280 --> 00:30:12,040
Speaker 1: Oh, how big of a number, Like if you had

620
00:30:12,040 --> 00:30:14,640
Speaker 1: a pie chart of the universe at the beginning in

621
00:30:14,680 --> 00:30:17,160
Speaker 1: the Big Bang, how big is the neutrino slice.

622
00:30:17,400 --> 00:30:19,160
Speaker 2: Yeah, so you wouldn't even be able to see the

623
00:30:19,200 --> 00:30:22,040
Speaker 2: protons on that pie chart because there are approximately one

624
00:30:22,440 --> 00:30:25,080
Speaker 2: billion neutrinos for every proton.

625
00:30:25,560 --> 00:30:28,320
Speaker 1: Well in terms of quantity, but in energy, how big

626
00:30:28,320 --> 00:30:30,120
Speaker 1: of a slice is it there?

627
00:30:30,160 --> 00:30:32,720
Speaker 2: The numbers are much more closely balanced. There are many

628
00:30:32,760 --> 00:30:36,280
Speaker 2: fewer protons, but protons have a huge mass compared to

629
00:30:36,360 --> 00:30:39,200
Speaker 2: neutrinos that have almost no mass. On the other hand,

630
00:30:39,280 --> 00:30:42,080
Speaker 2: the neutrinos have a lot more kinetic energy. Right they're

631
00:30:42,080 --> 00:30:45,240
Speaker 2: moving really really fast, They're almost at the speed of light,

632
00:30:45,640 --> 00:30:47,520
Speaker 2: so the energy is there are much better balanced that

633
00:30:47,520 --> 00:30:50,000
Speaker 2: are in the same order of magnitude. The numbers aren't

634
00:30:50,000 --> 00:30:53,000
Speaker 2: exactly determined, but the original question was about the number

635
00:30:53,080 --> 00:30:55,640
Speaker 2: of neutrinos in the universe, and so there we need

636
00:30:55,680 --> 00:31:00,000
Speaker 2: the number ratio, and the cosmic microwave background radiation tells

637
00:31:00,240 --> 00:31:03,120
Speaker 2: us that there are like three hundred and thirty million

638
00:31:03,200 --> 00:31:07,360
Speaker 2: neutrinos per cubic meter of space back then, and there

639
00:31:07,360 --> 00:31:10,360
Speaker 2: was less than one proton per cubic meter, so the

640
00:31:10,440 --> 00:31:12,040
Speaker 2: ratio is about a billion I.

641
00:31:12,080 --> 00:31:15,120
Speaker 1: See, so neutrino's were a pretty significant slice of the universe,

642
00:31:15,160 --> 00:31:17,480
Speaker 1: but in terms of quantity, like number of neutrinos because

643
00:31:17,480 --> 00:31:20,080
Speaker 1: they're so small at night that the number of them

644
00:31:20,160 --> 00:31:23,080
Speaker 1: dwarfs the number of protons around us exactly.

645
00:31:23,160 --> 00:31:26,840
Speaker 2: So there's this incredible ocean of neutrinos back in the

646
00:31:26,880 --> 00:31:30,720
Speaker 2: early universe and still today. Like the density of neutrinos

647
00:31:30,720 --> 00:31:34,080
Speaker 2: has dropped because the universe expands and everything gets more

648
00:31:34,120 --> 00:31:37,320
Speaker 2: dilute except for dark energy, but most of those neutrinos

649
00:31:37,320 --> 00:31:41,240
Speaker 2: are still around. It's called the cosmic neutrino background, and

650
00:31:41,280 --> 00:31:44,360
Speaker 2: it's something we're searching for in neutrino experiments.

651
00:31:44,960 --> 00:31:47,600
Speaker 1: Does it depend still on the number of protons? Is

652
00:31:47,640 --> 00:31:50,000
Speaker 1: it the same ratio like three hundred and thirty million

653
00:31:50,040 --> 00:31:52,040
Speaker 1: to one or billion to.

654
00:31:51,960 --> 00:31:54,200
Speaker 2: One, depends a little bit what you count as a proton.

655
00:31:54,600 --> 00:31:56,920
Speaker 2: Like some of those protons go on to make helium.

656
00:31:57,040 --> 00:31:59,480
Speaker 2: There's still protons in there, but like now we call

657
00:31:59,520 --> 00:32:02,560
Speaker 2: them helium instead of protons or hydrogen. But most of

658
00:32:02,600 --> 00:32:04,880
Speaker 2: those protons are still around, and most of those neutrinos

659
00:32:04,880 --> 00:32:07,480
Speaker 2: are still around, and because they're both matter, they both

660
00:32:07,520 --> 00:32:10,520
Speaker 2: get diluted in the same way as the universe expands,

661
00:32:10,920 --> 00:32:13,200
Speaker 2: and so their ratio is approximately the same.

662
00:32:14,200 --> 00:32:16,000
Speaker 1: Then to get account of the number and neutrinos, we

663
00:32:16,000 --> 00:32:18,160
Speaker 1: need a count of the number of protons, So how

664
00:32:18,160 --> 00:32:19,760
Speaker 1: many protons are there in the universe.

665
00:32:20,080 --> 00:32:22,640
Speaker 2: So in the observable universe, we don't know what's in

666
00:32:22,680 --> 00:32:25,720
Speaker 2: the full universe right past where we can see. We

667
00:32:25,800 --> 00:32:27,920
Speaker 2: know the density of protons, which is about a fifth

668
00:32:27,960 --> 00:32:31,760
Speaker 2: per cubic meter, and we know roughly the volume of

669
00:32:31,800 --> 00:32:35,920
Speaker 2: the observable universe, which is like ten to the eighty

670
00:32:36,320 --> 00:32:39,720
Speaker 2: cubic meters or so, and that means around ten to

671
00:32:39,800 --> 00:32:44,440
Speaker 2: the seventy nine protons in the observable universe. That's ten

672
00:32:44,760 --> 00:32:47,400
Speaker 2: with seventy nine zeros. It's not even like a name

673
00:32:47,480 --> 00:32:47,840
Speaker 2: for that.

674
00:32:47,800 --> 00:32:50,000
Speaker 1: Number, Sure there is, we can make one.

675
00:32:49,960 --> 00:32:52,000
Speaker 2: Up, right, there will be soon.

676
00:32:52,040 --> 00:32:54,440
Speaker 1: What's the number bananion?

677
00:32:56,800 --> 00:33:00,640
Speaker 2: Coincidentally, there's exactly one bananion of protons in the universe.

678
00:33:00,880 --> 00:33:03,560
Speaker 1: Oh my gosh, such a coincidence.

679
00:33:03,080 --> 00:33:08,120
Speaker 2: Which means that there's a billion bananians of neutrinos in

680
00:33:08,160 --> 00:33:11,080
Speaker 2: the universe, because it's about a billion neutrinos per.

681
00:33:10,960 --> 00:33:13,760
Speaker 1: Proton, So ten to the what eighty eight.

682
00:33:13,800 --> 00:33:17,200
Speaker 2: About ten to the eighty eight neutrinos in the observable universe.

683
00:33:17,280 --> 00:33:21,760
Speaker 1: Observable universe, but the observable universe is getting bigger every day. Right,

684
00:33:22,320 --> 00:33:23,720
Speaker 1: So that number is going up.

685
00:33:23,680 --> 00:33:26,040
Speaker 2: Actually depends a little bit how you think about distance.

686
00:33:26,320 --> 00:33:28,920
Speaker 2: The universe is expanding faster than the speed of light,

687
00:33:29,000 --> 00:33:31,160
Speaker 2: so the fraction of stuff in the universe we can

688
00:33:31,200 --> 00:33:34,080
Speaker 2: see is actually shrinking, right, And eventually a lot of

689
00:33:34,080 --> 00:33:36,960
Speaker 2: stuff is going to fall outside of our horizon. So

690
00:33:37,000 --> 00:33:40,000
Speaker 2: the number of particles in the observable universe is actually decreasing.

691
00:33:40,440 --> 00:33:45,120
Speaker 1: WHOA, the universe is its outgrowing how far we can see.

692
00:33:45,080 --> 00:33:48,880
Speaker 2: Yeah, exactly. The universe is expanding faster than our horizon is,

693
00:33:49,440 --> 00:33:53,640
Speaker 2: so particles are disappearing from the observable universe. That's another

694
00:33:53,680 --> 00:33:55,360
Speaker 2: reason why the number is not fixed.

695
00:33:55,520 --> 00:33:58,120
Speaker 1: Well, it may not even be fixed, right, Like, maybe

696
00:33:58,160 --> 00:34:01,000
Speaker 1: the universe is infinite, in which case there's maybe an

697
00:34:01,000 --> 00:34:02,240
Speaker 1: infinite number of neutrinos.

698
00:34:02,560 --> 00:34:04,640
Speaker 2: Yeah, exactly. In that case, you could still measure the

699
00:34:04,640 --> 00:34:07,080
Speaker 2: density of neutrinos like three hundred and thirty million per

700
00:34:07,120 --> 00:34:10,160
Speaker 2: cubic meter, but the total number in the whole universe

701
00:34:10,400 --> 00:34:13,879
Speaker 2: would be infinite. If the universe is infinite, and if

702
00:34:13,920 --> 00:34:17,160
Speaker 2: the universe beyond a horizon is similar to the bits

703
00:34:17,160 --> 00:34:19,360
Speaker 2: that we see here, could be that what's beyond the

704
00:34:19,400 --> 00:34:21,319
Speaker 2: horizon is very different, right, And then we live in

705
00:34:21,360 --> 00:34:23,400
Speaker 2: a weird patch of the universe.

706
00:34:23,239 --> 00:34:25,719
Speaker 1: Right right, It depends and we don't know, is what

707
00:34:25,760 --> 00:34:30,240
Speaker 1: you're saying. But what do you think is the ratio

708
00:34:30,560 --> 00:34:34,320
Speaker 1: of like in the universe, the ratio between neutrinos and Daniels.

709
00:34:36,239 --> 00:34:40,360
Speaker 1: Is it infinite to one or is there a fixed number?

710
00:34:41,719 --> 00:34:44,280
Speaker 2: That's the question philosopher has been wondering about for thousands

711
00:34:44,280 --> 00:34:45,840
Speaker 2: of years, and we're not going to answer it today

712
00:34:45,840 --> 00:34:46,640
Speaker 2: on the podcast.

713
00:34:48,600 --> 00:34:50,359
Speaker 1: That's right. We don't have the time. That's why we're

714
00:34:50,400 --> 00:34:51,239
Speaker 1: not answering.

715
00:34:50,960 --> 00:34:53,600
Speaker 2: That's right, exactly. No, I think if there are other

716
00:34:53,719 --> 00:34:56,319
Speaker 2: Daniels out there, there's still not me because I'm not

717
00:34:56,360 --> 00:34:59,600
Speaker 2: experiencing them, even if they think that there Daniel. I'm

718
00:34:59,640 --> 00:35:02,319
Speaker 2: experien think this one, which makes this one different, which

719
00:35:02,360 --> 00:35:05,640
Speaker 2: makes me unique. I'm only experiencing one Daniel.

720
00:35:05,480 --> 00:35:08,600
Speaker 1: Unless they're having the exact same experience you are, in

721
00:35:08,600 --> 00:35:11,279
Speaker 1: which case, in which case, there the outside can't tell

722
00:35:11,280 --> 00:35:12,160
Speaker 1: the difference.

723
00:35:13,080 --> 00:35:16,560
Speaker 2: But we can from inside, right inside the Daniel horizon,

724
00:35:16,800 --> 00:35:18,560
Speaker 2: you can tell which Daniel you are.

725
00:35:19,160 --> 00:35:21,800
Speaker 1: But your feeling of uniqueness is the same feeling of

726
00:35:22,000 --> 00:35:23,719
Speaker 1: unique is the other Daniel's having.

727
00:35:23,800 --> 00:35:26,320
Speaker 2: Yeah, that's right, But I'm only feeling my feeling of uniqueness.

728
00:35:26,360 --> 00:35:28,160
Speaker 2: I'm not feeling bears. Oh, I see.

729
00:35:28,200 --> 00:35:30,840
Speaker 1: So to you, there's only one Daniel, yeah, but maybe

730
00:35:30,840 --> 00:35:33,200
Speaker 1: to someone outside of the universe there is an infinite

731
00:35:33,239 --> 00:35:33,960
Speaker 1: number of Daniels.

732
00:35:34,080 --> 00:35:36,440
Speaker 2: Yeah. And it means and we don't know, And to

733
00:35:36,480 --> 00:35:38,719
Speaker 2: me is all that matters, because I'm the only consciousness

734
00:35:38,719 --> 00:35:40,280
Speaker 2: I'm actually aware of in the universe.

735
00:35:41,120 --> 00:35:45,759
Speaker 1: But I'm not asking what matters to you. I'm wondering

736
00:35:45,800 --> 00:35:47,000
Speaker 1: what matters to me, Daniel.

737
00:35:50,120 --> 00:35:51,239
Speaker 2: I don't know if you're even real.

738
00:35:51,400 --> 00:35:55,520
Speaker 1: So that's right, We're all in them some AI's imagination.

739
00:35:56,600 --> 00:35:58,880
Speaker 1: All right, Well, I think that answers the question for Sam.

740
00:35:59,239 --> 00:36:01,840
Speaker 1: The estimate of the number of neutrinos in the observable

741
00:36:01,920 --> 00:36:05,520
Speaker 1: universe is ten to the eighty eight neutrinos plus or

742
00:36:05,600 --> 00:36:09,560
Speaker 1: minus ten to the what eighty seven.

743
00:36:10,120 --> 00:36:12,719
Speaker 2: Seven pluster minus infinity.

744
00:36:12,800 --> 00:36:16,839
Speaker 1: Probably there's our pleasure minus infinity. All right, Well, let's

745
00:36:16,840 --> 00:36:19,680
Speaker 1: get to our last question of the episode, which is

746
00:36:19,719 --> 00:36:23,000
Speaker 1: about gravitational waves and can you serve one? So let's

747
00:36:23,000 --> 00:36:25,680
Speaker 1: get into that, but first let's take another quick break.

748
00:36:38,040 --> 00:36:39,880
Speaker 1: All right, Our last question of the day comes from

749
00:36:40,000 --> 00:36:43,080
Speaker 1: Klai wants to know about gravitational waves.

750
00:36:43,840 --> 00:36:47,200
Speaker 5: Howdy Daniel and Jorge. I was wondering how would feel

751
00:36:47,239 --> 00:36:51,279
Speaker 5: to be hit by a gravitational wave? We have detected

752
00:36:51,360 --> 00:36:55,960
Speaker 5: infinitely weak waves from Earth, but imagine if we were

753
00:36:56,000 --> 00:36:59,400
Speaker 5: close to two black holes revolving around each other and

754
00:36:59,400 --> 00:37:03,239
Speaker 5: eventually colliding and merging. How would it feel to get

755
00:37:03,320 --> 00:37:07,239
Speaker 5: hit by a gravitational wave? And would it be the

756
00:37:07,280 --> 00:37:10,480
Speaker 5: same as a wave? And finally, would your organs be damaged?

757
00:37:11,160 --> 00:37:16,280
Speaker 1: Interesting question. It sounds like Clay is planning a trip. Perhaps.

758
00:37:18,360 --> 00:37:21,279
Speaker 2: I think Klay wants to experience the universe, wants to

759
00:37:21,360 --> 00:37:24,560
Speaker 2: feel gravitation waves, not just read about it online.

760
00:37:25,280 --> 00:37:27,600
Speaker 1: Well, I think one of the things is that, first

761
00:37:27,600 --> 00:37:30,280
Speaker 1: of all, we're all experiencing gravitation waves right now.

762
00:37:30,200 --> 00:37:33,560
Speaker 2: Right, Yeah, that's true. Gravitational waves are everywhere. They fill

763
00:37:33,600 --> 00:37:38,280
Speaker 2: the universe because they're generated anytime any mass is accelerated.

764
00:37:38,760 --> 00:37:42,120
Speaker 2: So you're in orbit, you're generating gravitational waves. You get

765
00:37:42,120 --> 00:37:47,520
Speaker 2: out of bed, you're generating gravitational waves. Gravitational waves are everywhere, right.

766
00:37:47,400 --> 00:37:50,280
Speaker 1: We're experiencing them. We're generating them like if a car

767
00:37:50,760 --> 00:37:55,160
Speaker 1: accelerates in front of me, technically gonna feel or I'm

768
00:37:55,160 --> 00:37:58,760
Speaker 1: going to experience the gravitational wave generated by the car.

769
00:37:58,880 --> 00:38:02,480
Speaker 2: Right, It's very hard to feel these things because they're very,

770
00:38:02,520 --> 00:38:06,000
Speaker 2: very gentle. Remember that gravity is like the dominant force

771
00:38:06,040 --> 00:38:07,839
Speaker 2: and the structure of the universe, but it's also the

772
00:38:07,880 --> 00:38:10,560
Speaker 2: weakest force, if you even call it a force, so

773
00:38:10,640 --> 00:38:12,920
Speaker 2: much weaker than the forces that hold your body together

774
00:38:12,960 --> 00:38:13,560
Speaker 2: for example.

775
00:38:13,880 --> 00:38:16,920
Speaker 1: Right, they're super mellow, hard to detect, but we can

776
00:38:17,040 --> 00:38:19,520
Speaker 1: detect some of the ones that come from deep in

777
00:38:19,600 --> 00:38:22,880
Speaker 1: outer space, that come from black holes or heavy things

778
00:38:23,120 --> 00:38:24,800
Speaker 1: circling each other and then colliding.

779
00:38:25,000 --> 00:38:27,839
Speaker 2: Exactly. The way to detect gravitational waves is to look

780
00:38:27,880 --> 00:38:31,640
Speaker 2: for extremely loud sources of them, things that make very

781
00:38:31,719 --> 00:38:35,600
Speaker 2: dramatic gravitational waves. And so two black holes, which are

782
00:38:35,600 --> 00:38:39,520
Speaker 2: two enormous masses orbiting each other very very quickly just

783
00:38:39,560 --> 00:38:43,960
Speaker 2: before they collide, are very loud sources of gravitational waves.

784
00:38:44,360 --> 00:38:46,640
Speaker 2: So even though we're very far from them, we can

785
00:38:46,680 --> 00:38:49,560
Speaker 2: be like a billion light years away, we can still

786
00:38:49,600 --> 00:38:54,920
Speaker 2: detect those gravitational waves here on Earth with super sensitive detectors.

787
00:38:54,560 --> 00:38:56,560
Speaker 1: Right here on Earth. By the time that they get

788
00:38:56,600 --> 00:38:58,719
Speaker 1: to us, they're super weak because I guess, like a

789
00:38:58,840 --> 00:39:02,160
Speaker 1: ripple in a laketational waves get weaker as they expand

790
00:39:02,239 --> 00:39:03,120
Speaker 1: right from their source.

791
00:39:03,280 --> 00:39:05,399
Speaker 2: Yeah, as you get further from the source, they get

792
00:39:05,440 --> 00:39:06,560
Speaker 2: weaker and weaker.

793
00:39:06,760 --> 00:39:08,879
Speaker 1: Right, And as you said, the ones we're detecting now

794
00:39:08,880 --> 00:39:11,520
Speaker 1: with LIGO, which is the big physics instrument we have

795
00:39:11,600 --> 00:39:15,400
Speaker 1: here on Earth, those happen billions of light years away.

796
00:39:15,920 --> 00:39:18,920
Speaker 1: And I think the Khalist question is, like, what if

797
00:39:18,960 --> 00:39:22,480
Speaker 1: you're closer to that source of gravitational waves, Like, what

798
00:39:22,560 --> 00:39:24,640
Speaker 1: if you're right next to those two black holes glide in?

799
00:39:25,719 --> 00:39:28,320
Speaker 1: What would it feel like to have this giant gravitation

800
00:39:28,440 --> 00:39:29,439
Speaker 1: wave pass three?

801
00:39:29,680 --> 00:39:31,600
Speaker 2: Yeah, it's a really cool question to think about it.

802
00:39:31,600 --> 00:39:34,120
Speaker 2: I think we should like zoom in on what happens

803
00:39:34,160 --> 00:39:37,680
Speaker 2: first to like individual particles in your body, and then

804
00:39:37,719 --> 00:39:39,279
Speaker 2: think about what that would feel like.

805
00:39:40,320 --> 00:39:42,200
Speaker 1: There's a way. Wait, but the scenario is how close

806
00:39:42,239 --> 00:39:43,800
Speaker 1: am I to these gravitational waves?

807
00:39:43,960 --> 00:39:46,240
Speaker 2: So imagine we're just like a few tens of thousands

808
00:39:46,280 --> 00:39:49,319
Speaker 2: of kilometers away from these two black holes that are

809
00:39:49,400 --> 00:39:50,120
Speaker 2: orbiting each other.

810
00:39:50,840 --> 00:39:53,120
Speaker 1: Aren't black holes usually bigger than a few tens of

811
00:39:53,160 --> 00:39:56,520
Speaker 1: thousands of kilometers or are you imagining like two small ones?

812
00:39:56,560 --> 00:39:59,280
Speaker 2: Well, the kind of collisions we've seen are between black

813
00:39:59,280 --> 00:40:02,640
Speaker 2: holes that have like thirty to fifty solar masses, and

814
00:40:02,680 --> 00:40:04,920
Speaker 2: those have an event horizon radius of like one hundred

815
00:40:04,960 --> 00:40:08,439
Speaker 2: kilometers or less, So if you're thirty thousand kilometers away,

816
00:40:08,440 --> 00:40:10,440
Speaker 2: you're definitely not inside the event horizon.

817
00:40:10,600 --> 00:40:12,480
Speaker 1: Okay, so these are pretty small black holes.

818
00:40:12,719 --> 00:40:14,600
Speaker 2: Yeah, but these are the kinds of black holes we've

819
00:40:14,600 --> 00:40:15,840
Speaker 2: been able to see collide.

820
00:40:16,120 --> 00:40:18,600
Speaker 1: Ooh, all right, so then we're a few tens of

821
00:40:18,640 --> 00:40:22,400
Speaker 1: thousands of kilometers away from these two black holes smashing

822
00:40:22,440 --> 00:40:23,760
Speaker 1: into each other exactly.

823
00:40:23,920 --> 00:40:26,960
Speaker 2: And on a human, if you're like thirty fifty thousand

824
00:40:27,000 --> 00:40:29,920
Speaker 2: kilometers away from two black holes that have like the

825
00:40:29,960 --> 00:40:33,520
Speaker 2: mass of thirty or fifty times the sun, then you're

826
00:40:33,560 --> 00:40:36,600
Speaker 2: going to feel what's called a strain of about one millimeter.

827
00:40:37,040 --> 00:40:40,279
Speaker 2: The strain is how much your body is getting squeezed

828
00:40:40,560 --> 00:40:43,200
Speaker 2: by the gravitational wave. And this is what we measure

829
00:40:43,280 --> 00:40:46,600
Speaker 2: also here on Earth with LEGO, we have these innerferometers,

830
00:40:46,600 --> 00:40:50,120
Speaker 2: these very long laser legs that get squeezed and lengthened

831
00:40:50,160 --> 00:40:53,319
Speaker 2: as the gravitational wave passes by. The ones here on

832
00:40:53,400 --> 00:40:55,960
Speaker 2: Earth are so faint that the measure strains of like

833
00:40:56,280 --> 00:40:59,480
Speaker 2: one times ten to the negative twenty one, which means

834
00:40:59,520 --> 00:41:02,600
Speaker 2: that like the two mile leg of the inferometer gets

835
00:41:02,600 --> 00:41:05,320
Speaker 2: shorter by that factor. It's a really really tiny factor.

836
00:41:05,840 --> 00:41:10,600
Speaker 1: But unless how much like space is being stretched or compressed, right, Like,

837
00:41:10,719 --> 00:41:14,640
Speaker 1: not necessarily something in space, right, because it's something in

838
00:41:14,680 --> 00:41:17,600
Speaker 1: space is sort of holing on to itself. But you're

839
00:41:17,640 --> 00:41:19,480
Speaker 1: talking about the stretching of space itself.

840
00:41:20,000 --> 00:41:23,240
Speaker 2: Yeah, the changing of the distance between two particles. For example,

841
00:41:23,840 --> 00:41:26,399
Speaker 2: So imagine you have two particles and you're a few

842
00:41:26,440 --> 00:41:29,120
Speaker 2: tens of thousands of kilometers away from these black holes

843
00:41:29,160 --> 00:41:32,839
Speaker 2: that are e merging, and they're generating gravitational waves. What's

844
00:41:32,840 --> 00:41:35,200
Speaker 2: going to happen is they're going to change the distance

845
00:41:35,239 --> 00:41:38,400
Speaker 2: between the two atoms. Right, So, for example, that the

846
00:41:38,440 --> 00:41:41,279
Speaker 2: distance gets longer than those two atoms, if they were

847
00:41:41,320 --> 00:41:43,880
Speaker 2: like bound together somehow, then they're going to feel an

848
00:41:43,920 --> 00:41:46,520
Speaker 2: attractive force to pull them back to where they were

849
00:41:46,560 --> 00:41:51,040
Speaker 2: in equilibrium. If the gravitational wave is very slow, they're

850
00:41:51,040 --> 00:41:53,319
Speaker 2: going to be able to basically stain in equilibrium and

851
00:41:53,360 --> 00:41:57,040
Speaker 2: nothing really happens. But if the gravitational frequency is high,

852
00:41:57,400 --> 00:42:00,520
Speaker 2: if the sort of squeezing and pulling and pushing is fast,

853
00:42:01,080 --> 00:42:03,360
Speaker 2: they'll effectively feel a force and they might start to

854
00:42:03,360 --> 00:42:06,640
Speaker 2: oscillate back and forth. That's kind of what happens in Lego.

855
00:42:07,880 --> 00:42:10,520
Speaker 1: Like the stretching of space is kind of like how

856
00:42:10,600 --> 00:42:12,719
Speaker 1: much space wants to stretch you.

857
00:42:13,120 --> 00:42:15,960
Speaker 2: Yeah, the distance between those two particles or the two

858
00:42:16,040 --> 00:42:19,239
Speaker 2: mirrors in Lego gets longer or shorter based on the

859
00:42:19,239 --> 00:42:22,600
Speaker 2: gravitational wave. But then the interaction between the two particles,

860
00:42:22,640 --> 00:42:25,080
Speaker 2: or the structural strength of the thing, whatever, has a

861
00:42:25,200 --> 00:42:27,320
Speaker 2: natural length that it wants to be at, so to

862
00:42:27,360 --> 00:42:29,960
Speaker 2: try to return to that natural length. Like if you

863
00:42:30,000 --> 00:42:33,879
Speaker 2: imagine a spring between these two particles, you pull them apart, well,

864
00:42:33,880 --> 00:42:35,400
Speaker 2: the spring is going to pull them back.

865
00:42:35,280 --> 00:42:37,440
Speaker 1: Together, right, So then you're saying, like, if I'm a

866
00:42:37,440 --> 00:42:40,320
Speaker 1: few tens of thousands of kilometers from these black holes,

867
00:42:40,360 --> 00:42:43,400
Speaker 1: and I would feel about a one millimeter stretch in

868
00:42:43,440 --> 00:42:45,760
Speaker 1: my body, or space would want to stretch my body

869
00:42:45,800 --> 00:42:47,719
Speaker 1: about one millimeter mm hmm.

870
00:42:47,920 --> 00:42:50,480
Speaker 2: And based on the frequency, you're going to get shaken

871
00:42:50,600 --> 00:42:53,320
Speaker 2: by one millimeter. It's not like you just get pulled

872
00:42:53,320 --> 00:42:55,840
Speaker 2: by one millimeter in one direction and then you stay there.

873
00:42:56,000 --> 00:42:59,680
Speaker 2: A gravitational wave is a wave. It's oscillating, and depending

874
00:42:59,680 --> 00:43:02,040
Speaker 2: on the frequency, if it's like a fast wave or

875
00:43:02,080 --> 00:43:04,960
Speaker 2: a slow wave, it's going to shake you at that speed,

876
00:43:05,000 --> 00:43:07,040
Speaker 2: so it might like pull you in one direction and

877
00:43:07,080 --> 00:43:09,239
Speaker 2: then squeeze you in that direction and pull you in

878
00:43:09,280 --> 00:43:12,560
Speaker 2: the other direction. So there's this pulling, the stretching, and

879
00:43:12,600 --> 00:43:15,600
Speaker 2: the squeezing. So right now we're talking about the amplitude

880
00:43:15,800 --> 00:43:19,600
Speaker 2: about one millimeter, but the frequency of that is also important,

881
00:43:19,840 --> 00:43:22,080
Speaker 2: and that depends on the orbits of these black holes.

882
00:43:22,360 --> 00:43:24,759
Speaker 2: How many times are they passing around each other. That

883
00:43:24,800 --> 00:43:28,080
Speaker 2: determines the frequency of this gravitational wave. If you're nearby

884
00:43:28,120 --> 00:43:30,839
Speaker 2: these black holes, you're basically going to get shaken from

885
00:43:30,880 --> 00:43:32,400
Speaker 2: the inside.

886
00:43:31,880 --> 00:43:34,799
Speaker 1: Right, And you're saying kind of depending on the frequency,

887
00:43:35,000 --> 00:43:37,759
Speaker 1: it might be dangerous or not. Like if it was

888
00:43:37,800 --> 00:43:40,880
Speaker 1: shaking really slowly, you probably your body can probably adjust

889
00:43:40,880 --> 00:43:44,120
Speaker 1: to that shaking. But if it's shaking super fast, then

890
00:43:44,200 --> 00:43:45,960
Speaker 1: it might scramble your insides.

891
00:43:46,040 --> 00:43:49,160
Speaker 2: You might scramble your insides. You might also experience it

892
00:43:49,200 --> 00:43:52,160
Speaker 2: in a weird way, like it might be like being

893
00:43:52,239 --> 00:43:55,560
Speaker 2: at a concert. Sound waves at a concert also shake

894
00:43:55,640 --> 00:43:59,319
Speaker 2: your body and you experience them as sound. If you're

895
00:43:59,360 --> 00:44:02,800
Speaker 2: out in space near two black holes, you might literally

896
00:44:03,120 --> 00:44:07,120
Speaker 2: hear the gravitational waves because like the drums in your

897
00:44:07,160 --> 00:44:08,360
Speaker 2: ear will get shaken.

898
00:44:08,800 --> 00:44:11,440
Speaker 1: Whoa as put everything else in your body.

899
00:44:11,200 --> 00:44:13,600
Speaker 2: As would everything else, Just like at a concert. Right

900
00:44:13,840 --> 00:44:16,120
Speaker 2: when you're in the moshpit at that concert, your toes

901
00:44:16,120 --> 00:44:18,080
Speaker 2: are getting shaken, even though your ears are the only

902
00:44:18,120 --> 00:44:21,399
Speaker 2: ones actually transmitting sound to your brain. The same way

903
00:44:21,400 --> 00:44:23,880
Speaker 2: a gravitational wave can be squeezing and pulling on your

904
00:44:23,880 --> 00:44:26,160
Speaker 2: whole body, but your ears might be the only ones

905
00:44:26,200 --> 00:44:26,799
Speaker 2: picking it up.

906
00:44:27,400 --> 00:44:29,399
Speaker 1: I've never been in a moshpit, but I'll take your

907
00:44:29,480 --> 00:44:33,440
Speaker 1: word for it, so you might feel it. But is

908
00:44:33,480 --> 00:44:36,359
Speaker 1: it dangerous? Like if it's high frequency enough, and these

909
00:44:36,400 --> 00:44:39,120
Speaker 1: things are pretty high frequency by the time they smash together,

910
00:44:39,280 --> 00:44:41,840
Speaker 1: it's like super high frequency, right.

911
00:44:41,840 --> 00:44:44,160
Speaker 2: Yeah, they can get to be very high frequency. And

912
00:44:44,280 --> 00:44:47,960
Speaker 2: actually the frequency they experience is even higher than we

913
00:44:48,080 --> 00:44:53,000
Speaker 2: observe because there's gravitational time dilation. These black holes, of

914
00:44:53,000 --> 00:44:56,040
Speaker 2: course have super high curvature, and now one black hole

915
00:44:56,080 --> 00:44:59,360
Speaker 2: is near another one, it's experiencing the gravitational time dilation

916
00:44:59,520 --> 00:45:02,880
Speaker 2: of that black hole, so time is super slowed down.

917
00:45:03,280 --> 00:45:07,120
Speaker 2: So what we're observing is the slow down gravitational wave

918
00:45:07,480 --> 00:45:11,240
Speaker 2: being emitted by these event horizons. That's already taken into account.

919
00:45:11,520 --> 00:45:14,480
Speaker 2: If it wasn't, then the frequency would be much much higher.

920
00:45:15,160 --> 00:45:18,000
Speaker 1: Well, I guess from what we know of these smashing

921
00:45:18,040 --> 00:45:20,760
Speaker 1: black holes or the ones we've seen, then the frequency

922
00:45:20,760 --> 00:45:24,040
Speaker 1: we've seen, and how fast there actually are closer to

923
00:45:24,080 --> 00:45:27,240
Speaker 1: the source, would they actually kill you at this distance?

924
00:45:27,400 --> 00:45:29,360
Speaker 1: Like at some point they'll start to rip apart the

925
00:45:29,400 --> 00:45:33,319
Speaker 1: bonds between the proteins in your body, right, or you know,

926
00:45:34,120 --> 00:45:36,000
Speaker 1: it'll basically scramble your brain.

927
00:45:37,719 --> 00:45:39,359
Speaker 2: I don't think I can say. It depends a lot

928
00:45:39,360 --> 00:45:43,279
Speaker 2: on the internal biological friction, like how much energy is

929
00:45:43,280 --> 00:45:46,759
Speaker 2: actually going to get absorbed, and how squishy your body is,

930
00:45:46,920 --> 00:45:49,760
Speaker 2: how resilient it is, depends a lot on the exact

931
00:45:49,920 --> 00:45:52,520
Speaker 2: kind of tissue. I think all I can do is

932
00:45:52,760 --> 00:45:55,840
Speaker 2: treat your body as a sphere with ears and say

933
00:45:56,200 --> 00:45:58,160
Speaker 2: you'll probably hear it happening.

934
00:45:58,040 --> 00:46:00,279
Speaker 1: But you can probably make that calculation, right, Like you

935
00:46:00,320 --> 00:46:04,560
Speaker 1: can calculate this spignification point of a black hole, right,

936
00:46:04,719 --> 00:46:06,920
Speaker 1: like the point at which it would actually tear you

937
00:46:06,920 --> 00:46:09,080
Speaker 1: apart falling into a black hole. You can probably do

938
00:46:09,120 --> 00:46:11,000
Speaker 1: that for gravitational wave, right.

939
00:46:10,960 --> 00:46:13,319
Speaker 2: Yeah, But the energy that gets absorbed depends on this

940
00:46:13,400 --> 00:46:17,280
Speaker 2: internal friction. Like if there's no internal friction to your object,

941
00:46:17,560 --> 00:46:20,759
Speaker 2: it can get squeezed and squished and then be totally unharmed.

942
00:46:21,200 --> 00:46:24,080
Speaker 2: So how much energy is deposited, how much damage is

943
00:46:24,120 --> 00:46:28,400
Speaker 2: done depends entirely on the internal friction of that object.

944
00:46:28,480 --> 00:46:31,560
Speaker 2: It's not just dependent on the tidal forces.

945
00:46:31,400 --> 00:46:33,560
Speaker 1: Right right, But I imagine, I mean, we don't have

946
00:46:33,600 --> 00:46:35,319
Speaker 1: to do it now, or there's no pressure for you

947
00:46:35,360 --> 00:46:37,400
Speaker 1: to come up with an answer. But like, if you

948
00:46:37,440 --> 00:46:40,360
Speaker 1: could make the calculation for like a typical brain, what

949
00:46:40,480 --> 00:46:43,440
Speaker 1: are some of the maximum accelerations a brain can withstand

950
00:46:43,480 --> 00:46:46,520
Speaker 1: before it turns into you know, mush, and you can

951
00:46:46,560 --> 00:46:50,440
Speaker 1: maybe backtrack to find what kind of frequency of gravitation

952
00:46:50,480 --> 00:46:51,279
Speaker 1: waves would kill you.

953
00:46:51,400 --> 00:46:53,640
Speaker 2: Yeah, probably somebody who knows something about the brain could

954
00:46:53,640 --> 00:46:54,200
Speaker 2: figure that out.

955
00:46:56,440 --> 00:46:58,800
Speaker 1: What do we know about brains? We just use them.

956
00:46:59,000 --> 00:47:01,200
Speaker 2: I'm going to guess the answer is it depends, and

957
00:47:01,360 --> 00:47:02,920
Speaker 2: we don't know exactly.

958
00:47:03,480 --> 00:47:06,040
Speaker 1: You read my brain. That's exactly what I was.

959
00:47:06,040 --> 00:47:09,919
Speaker 2: Thinking, exactly. I just got a gravitational wave idea into

960
00:47:09,920 --> 00:47:10,319
Speaker 2: my brain.

961
00:47:10,920 --> 00:47:13,840
Speaker 1: But again, I feel like this is just firm standing

962
00:47:13,880 --> 00:47:17,480
Speaker 1: tens of thousands of kilometers away. May you say, maybe

963
00:47:17,520 --> 00:47:20,279
Speaker 1: we might survive this. I don't know, because don't these

964
00:47:20,320 --> 00:47:23,000
Speaker 1: things go pretty high frequency? Even a one millimeter strain

965
00:47:23,080 --> 00:47:24,640
Speaker 1: might be enough to mois your brain.

966
00:47:24,760 --> 00:47:27,279
Speaker 2: One milimeter strain is pretty big, so I think it

967
00:47:27,360 --> 00:47:29,680
Speaker 2: might be enough. I mean, I think one millimeter strain

968
00:47:29,800 --> 00:47:32,440
Speaker 2: is much more than you ever experienced at a concert.

969
00:47:32,800 --> 00:47:36,480
Speaker 2: Even very very high intensity sound waves don't actually like

970
00:47:36,800 --> 00:47:39,399
Speaker 2: move the molecules in your body by a millimeter. That's

971
00:47:39,440 --> 00:47:42,400
Speaker 2: a pretty huge displacement. And you've got lots of really

972
00:47:42,400 --> 00:47:45,000
Speaker 2: sensitive things inside your body that are much smaller than

973
00:47:45,040 --> 00:47:48,960
Speaker 2: one millimeter, So one millimeters squeezing and stretching could totally

974
00:47:48,960 --> 00:47:51,680
Speaker 2: destroy like really sensitive little biomachineries.

975
00:47:52,680 --> 00:47:59,200
Speaker 1: So smash bit, not moshpit, like your brain gets washed.

976
00:47:59,480 --> 00:48:01,320
Speaker 2: Yeah, I think it might be like being in a blender.

977
00:48:02,800 --> 00:48:06,560
Speaker 1: Great, then I imagine if you get closer to these

978
00:48:06,920 --> 00:48:09,600
Speaker 1: circling black holes and it just gets more dangerous, right,

979
00:48:09,719 --> 00:48:12,000
Speaker 1: because then the waves could get much more intense.

980
00:48:12,360 --> 00:48:15,040
Speaker 2: Exactly, the amplitude of the waves just grows as you

981
00:48:15,080 --> 00:48:17,680
Speaker 2: get closer. The strain gets larger and larger.

982
00:48:17,920 --> 00:48:20,839
Speaker 1: What if you're just a thousand kilometers away, how big

983
00:48:20,880 --> 00:48:21,560
Speaker 1: would the strain be.

984
00:48:21,920 --> 00:48:24,439
Speaker 2: Well, it goes like one over r a little, which

985
00:48:24,480 --> 00:48:27,520
Speaker 2: is a little bit weird, And so a thousand million

986
00:48:27,680 --> 00:48:31,239
Speaker 2: three times closer would be thirty times if you're like

987
00:48:31,320 --> 00:48:34,320
Speaker 2: thirty or ten times closer. If you're ten times closer,

988
00:48:34,320 --> 00:48:35,479
Speaker 2: it's going to be ten times as.

989
00:48:35,360 --> 00:48:38,040
Speaker 1: Strong, times times ten to the three. No, I mean

990
00:48:38,160 --> 00:48:42,120
Speaker 1: a q because because your are went down a tenth,

991
00:48:42,680 --> 00:48:45,880
Speaker 1: So then doesn't the intensity go up by a queue?

992
00:48:46,040 --> 00:48:49,440
Speaker 2: The strain goes like one over r oh linear? You

993
00:48:49,520 --> 00:48:51,399
Speaker 2: sure it's inverse linear? Yeah?

994
00:48:51,440 --> 00:48:54,200
Speaker 1: Oh, it's linear, all right, So then you would experience

995
00:48:54,200 --> 00:48:55,840
Speaker 1: it a one centimeter strain.

996
00:48:56,239 --> 00:48:58,719
Speaker 2: Yeah, ten times closer you get one centimeter strain.

997
00:48:58,800 --> 00:49:00,799
Speaker 1: Oh wait, yeah, that would be a lot.

998
00:49:02,239 --> 00:49:06,279
Speaker 2: That would definitely be a lot. CLI's asking how would

999
00:49:06,280 --> 00:49:08,799
Speaker 2: it feel to get hit by a gravitational wave? Would

1000
00:49:08,840 --> 00:49:11,480
Speaker 2: your organs be damaged? It depends a lot on the

1001
00:49:11,520 --> 00:49:15,239
Speaker 2: distance you get close enough, it could definitely scramble you. You

1002
00:49:14,840 --> 00:49:17,640
Speaker 2: get not too close, then you could probably hear it,

1003
00:49:17,800 --> 00:49:21,120
Speaker 2: like physically hear it without being destroyed. But I don't

1004
00:49:21,160 --> 00:49:23,760
Speaker 2: know exactly where that line is, and I don't recommend

1005
00:49:23,800 --> 00:49:24,480
Speaker 2: you figure it out.

1006
00:49:24,640 --> 00:49:25,000
Speaker 4: Mmmm.

1007
00:49:25,239 --> 00:49:27,440
Speaker 1: That's right. Keep it a thought experiment, Keep it a

1008
00:49:27,440 --> 00:49:31,480
Speaker 1: brain experiment to save your brain. All right. Well, I

1009
00:49:31,520 --> 00:49:34,560
Speaker 1: think that answers all of our questions. Some pretty interesting

1010
00:49:34,880 --> 00:49:37,920
Speaker 1: ideas here. Overall, the picture is that the universe is

1011
00:49:37,920 --> 00:49:41,279
Speaker 1: still mysterious. There's a lot we don't know, and there's

1012
00:49:41,280 --> 00:49:43,600
Speaker 1: still a lot of questions we can ask about it

1013
00:49:44,239 --> 00:49:45,080
Speaker 1: for us to explore.

1014
00:49:45,440 --> 00:49:47,640
Speaker 2: But we love that you ask these questions, and we

1015
00:49:47,719 --> 00:49:50,240
Speaker 2: love trying our best to answer them. We don't always

1016
00:49:50,239 --> 00:49:52,320
Speaker 2: know the answer. That's sort of the game of physics,

1017
00:49:52,520 --> 00:49:54,920
Speaker 2: figuring out where the edge of knowledge is and trying

1018
00:49:54,920 --> 00:49:56,799
Speaker 2: to push it forward a tiny little.

1019
00:49:56,520 --> 00:49:58,760
Speaker 1: Bit at least. That's one of the games one Daniel

1020
00:49:58,760 --> 00:49:59,120
Speaker 1: can play.

1021
00:50:00,560 --> 00:50:02,760
Speaker 2: What can we figure out if we have even more Daniels.

1022
00:50:04,880 --> 00:50:07,680
Speaker 1: All right, well, we hope you enjoyed that. Thanks for

1023
00:50:07,760 --> 00:50:09,319
Speaker 1: joining us. See you next time.

1024
00:50:14,000 --> 00:50:16,880
Speaker 2: For more science and curiosity, come find us on social

1025
00:50:16,920 --> 00:50:21,800
Speaker 2: media where we answer questions and post videos. We're on Twitter, Discorg, Insta,

1026
00:50:21,920 --> 00:50:25,640
Speaker 2: and now TikTok. Thanks for listening, and remember that Daniel

1027
00:50:25,680 --> 00:50:29,120
Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio.

1028
00:50:29,400 --> 00:50:34,560
Speaker 2: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,

1029
00:50:34,680 --> 00:50:37,040
Speaker 2: or wherever you listen to your favorite shows.