Speaker 1: Hey, Daniel, is it true that every electron is identical?
Speaker 2: Well, they all do have the same mass and the
Speaker 2: same charge, Like exactly, yeah, we think so.
Speaker 1: Isn't that weird? Why don't you expect them to be
Speaker 1: a little bit different each one.
Speaker 2: It's kind of exactly not weird. It means that no
Speaker 2: electrons are weird because they are all the same.
Speaker 1: I don't know, man, that's a bit wooky. Like if
Speaker 1: everyone in your neighborhood looked the same, wouldn't that be weird?
Speaker 2: I mean, I live in Orange County, so that's kind
Speaker 2: of what most people in the neighborhood are going for.
Speaker 1: Everyone's going for that scruffy physicist.
Speaker 2: Look more like plastic surgery face and beige housing.
Speaker 3: Well.
Speaker 1: I didn't want to say anything, but yeah, I do
Speaker 1: feel like you need a facelift in or at least
Speaker 1: a physics lift. Hi. I'm jorm At, cartoonist and the
Speaker 1: author of Oliver's Great Big Universe.
Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor
Speaker 2: at UC Irvine, and I'm proud of being one of
Speaker 2: a kind.
Speaker 1: But what kind is that? Daniel?
Speaker 2: That's the quiet that you. The pride might depend On. Mm, yeah,
Speaker 2: I define my kind man. There's nobody else like me. M.
Speaker 1: How do you know, though, have you met everyone who's
Speaker 1: ever existed? What if there was a Daniel with your
Speaker 1: exact same DNA that you know, lived two hundred years
Speaker 1: ago or could be living right now.
Speaker 2: It's possible, but they wouldn't have the same experiences. I
Speaker 2: have actually met another Daniel Whitson. He's an artist in
Speaker 2: the UK and quite accomplished.
Speaker 1: Ooh are you jealous?
Speaker 2: Am I jealous of the artist lifestyle?
Speaker 3: Oh?
Speaker 2: So many directions to go with that?
Speaker 1: What was that like? I don't think I've ever met
Speaker 1: a horhe Cham yet, but I think one exists somewhere
Speaker 1: in Indonesia.
Speaker 2: Maybe isn't there another one who has the Twitter handle
Speaker 2: at hohorhey.
Speaker 1: Cham somebody got that Twitter handle. I don't know if
Speaker 1: it is horri ha Jam or not, but I'm waiting
Speaker 1: for the blackmail email. Mm.
Speaker 2: Yeah, well, at least a digital copy of you exists.
Speaker 1: Or maybe I opened it years ago, but I forgot
Speaker 1: the password and the email I associated it with, so
Speaker 1: I don't know. Maybe I am my other meat.
Speaker 2: Yeah. Maybe we're old enough that younger versions of us
Speaker 2: are like alien minds.
Speaker 1: Oh wait, wouldn't that make you an alien?
Speaker 2: I think we're all still struggling to know ourselves.
Speaker 1: Right, well, we might all be aliens, right that Isn't
Speaker 1: there a theory that maybe life came to Earth from Mars.
Speaker 2: There is a theory like that called panspermia, that life
Speaker 2: may have originated somewhere else in the universe and then
Speaker 2: transported microbially hidden inside asteroids. It's a possibility all immigrants,
Speaker 2: kind of.
Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain
Speaker 1: the Universe, a production of iHeartRadio in.
Speaker 2: Which we do our best to digest this alien universe
Speaker 2: to explain all of the bizarre and amazing effects we
Speaker 2: see out there in terms of little mathematical stories that
Speaker 2: your mind and my mind and Jorge's mind can actually
Speaker 2: understand that we can talk about and digest and explain
Speaker 2: to you.
Speaker 1: That's right, because it is a pretty vast universe, and
Speaker 1: it's also pretty weird, full of unexplained phenomenon, unanswered questions,
Speaker 1: and potentially other versions of you out there.
Speaker 2: Raising all sorts of interesting philosophical questions like what does
Speaker 2: it mean to have an identical copy? And when you
Speaker 2: step into a transporter on Star Trek. Is it making
Speaker 2: a copy or actually transporting you?
Speaker 1: And what if, like there's another Jorge and another Daniel
Speaker 1: and they start a podcast. Can we sue them technically
Speaker 1: or maybe just retiring and give them the feat?
Speaker 2: Yeah, maybe it's time for the next generation, right.
Speaker 1: The new Daniel and Jorge explain the universe? Or Daniel
Speaker 1: and Horry explained the universe the next generation?
Speaker 2: Exactly? Yeah, one of us is Jean Luke and the
Speaker 2: other one is Riker.
Speaker 1: Wait wait, wait your name comes first, as I mean,
Speaker 1: I'm number two?
Speaker 2: Make it so? Okay?
Speaker 1: Can I just beque? Like, if I had to pick
Speaker 1: a character from the next generation, I would pick Q.
Speaker 2: Really not Data. Data might be the smartest one.
Speaker 1: A smart than Q can do anything in time and space.
Speaker 2: Q has no rules, so it doesn't really count exactly exactly,
Speaker 2: So you basically you want to be God, you're.
Speaker 1: Saying, I mean, who doesn't, come on, Q.
Speaker 2: Has so much responsibility. Every child who's dying of cancer.
Speaker 2: That's Q's fault, is it?
Speaker 1: Is it?
Speaker 2: Really? If you had the power to save a child
Speaker 2: and you didn't, then yeah, I think you're kind of responsible. Boy.
Speaker 1: That's a lot of gud killed.
Speaker 2: That's why I'd rather be data.
Speaker 1: Do you want to be data or be data?
Speaker 2: Hmm, Yeah, that's a good question. I actually just want
Speaker 2: to harness data's computing powers to solve mysteries of the universe. Yeah.
Speaker 1: That's a lot of makeup to put on every data.
Speaker 2: It's pretty heavy.
Speaker 1: Yeah, but anyways, welcome to our podcast. We also like
Speaker 1: to answer questions, not just talk about the answers that
Speaker 1: physicists have found. We also like to think about questions
Speaker 1: about the universe.
Speaker 2: Because everybody's got questions. I've got questions, You've got questions.
Speaker 2: Everybody who looks up at the night sky and wonders
Speaker 2: how it all works, or stares down between their toes
Speaker 2: and wants to understand the tiniest particles is yearning to
Speaker 2: understand how the world works, and that means asking questions.
Speaker 2: And on this podcast we answer questions at the edge
Speaker 2: of knowledge, those pose by physicists and those pose by listeners.
Speaker 2: So if you have questions about the nature of the
Speaker 2: universe or some explanation you've heard somewhere that didn't quite
Speaker 2: make sense to you, write to us to questions at
Speaker 2: Danielandjorge dot com. We really do. Right back to all
Speaker 2: of our listeners.
Speaker 1: Yeah, we're all curious about how the universe works, why
Speaker 1: we're in it, and how it's all put together. Although
Speaker 1: I'm not exactly curious about the particles in your toes
Speaker 1: or anyone's toes. Maybe we'll leave that part out of
Speaker 1: our questions.
Speaker 2: Wow, limits to your curiosity. That's disappointing.
Speaker 1: Yeah, I think there should be limits to anyone's curiosity.
Speaker 1: But yeah, we like to answer questions here on the
Speaker 1: podcast and plans from listeners, and so thanks to everyone
Speaker 1: who sent their questions in.
Speaker 2: Often I'll just write back, but sometimes we choose questions
Speaker 2: to answer on the podcast because we think lots of
Speaker 2: people will want to hear the answers.
Speaker 1: And so today on the podcast, we'll be tackling listener
Speaker 1: questions number forty nine. What are we gonna do when
Speaker 1: we hit fifty, Daniel, We're gonna have a mid podcast
Speaker 1: live crisis.
Speaker 2: We're gonna have a nice cake with fifty on it,
Speaker 2: and we're gonna fall asleep before the end of the.
Speaker 1: Party and then burn your house down.
Speaker 2: What it's gonna be virtual, of course, but.
Speaker 1: Yeah, we're answering listener questions here today and we have
Speaker 1: some awesome questions here from our listeners. There's one about
Speaker 1: black hole identity, there's one about neutrino and how many
Speaker 1: there are in the universe. And we also have a
Speaker 1: question about what it's like to serve a gravitational wave
Speaker 1: and what happens when you wipe out, Like where do
Speaker 1: you fall if it's a gravitational wave? But let's jump
Speaker 1: right in. Our first question comes from Matthew, who comes
Speaker 1: from Barry, Ontario.
Speaker 4: Hello, Daniel and Jorge. This is Matthew from Barry, Ontario
Speaker 4: up here in Canada, and like many of your listeners,
Speaker 4: I spend a bit of time thinking.
Speaker 1: About black holes.
Speaker 4: While I understand that it is impossible for us to
Speaker 4: see what lurks beyond the event horizon, I was curious
Speaker 4: if there is consensus in the scientific community about all
Speaker 4: black holes being the same, or if they could vary
Speaker 4: inside based on their density. For example, could a smaller
Speaker 4: black hole be not a black hole at all, but
Speaker 4: a dark star, while the super massive black holes at
Speaker 4: the center of some galaxies be a more traditional black
Speaker 4: hole or a string theory fuzz. Thank you very much
Speaker 4: for the wonderful show and I look forward to hearing
Speaker 4: your response.
Speaker 1: All right, I feel like this question ken has an
Speaker 1: identity problem in itself.
Speaker 2: It's so many questions but also one.
Speaker 1: But I think Matthew's basic question is about the identity
Speaker 1: of black holes, Like, are all black holes the same?
Speaker 1: Are they actually black holes? Could they be something else?
Speaker 1: Is it a case of mistaken identity? Or do all
Speaker 1: black holes come with an ID tag?
Speaker 2: Yeah, he's basically wondering what's going on inside black holes
Speaker 2: and if they all have to be the same on
Speaker 2: the inside, and whether the things we've seen out there
Speaker 2: in the universe that look like black holes could actually
Speaker 2: be a bunch of different kinds of stuff that all
Speaker 2: mimic black holes. So it's a really cool question guess
Speaker 2: at the heart of what we think is going on
Speaker 2: inside black holes.
Speaker 1: M Like, maybe what we call black holes are actually
Speaker 1: maybe a varity of different things.
Speaker 2: Yeah, it's possible. And two black holes with the same mass,
Speaker 2: do they have to look the same on the inside?
Speaker 1: Wait on how much mass is in it? Or Like,
Speaker 1: two things that look like black holes, are they actually
Speaker 1: black holes? Or do you think he's asking if they're
Speaker 1: the same, if there's any property that sets them apart?
Speaker 2: Yeah, I think he's asking both of those questions, and
Speaker 2: I think we should start with that. Like, if you
Speaker 2: have two black holes that have the same mass, are
Speaker 2: they the same thing? Are they indistinguishable? Or are they different?
Speaker 2: And this is a big question in general, relativity goes
Speaker 2: by the name of two black holes have hair? Essentially,
Speaker 2: are there texture or details? Are there tiny little properties
Speaker 2: that set two black holes apart the way two Like
Speaker 2: identical twins are always a little bit different. Are two
Speaker 2: black holes with the same mass, could they actually be
Speaker 2: a little bit different on the inside.
Speaker 1: Well, I feel there's two questions. One is like are
Speaker 1: they the same? And can you tell if they're the same?
Speaker 1: Aren't those two separate questions?
Speaker 2: Yeah, those are two separate questions. So as you can see,
Speaker 2: with black holes, we have like a constantly multiplying stream
Speaker 2: of questions.
Speaker 1: It's like a black hole of questions. It's a bit
Speaker 1: of a rabbit hole. It's a black rabbit hole. So
Speaker 1: which which question are we tackling? Can you tell if
Speaker 1: two black holes are different or whether they're actually different inside?
Speaker 2: Yeah, we can talk about all of it, but let's
Speaker 2: start with what's going on inside black holes, at least
Speaker 2: what we think is going on.
Speaker 1: Okay, well, you sort of mentioned the no hair problem,
Speaker 1: and that one's more of a like can you tell
Speaker 1: if two black holes are different problem?
Speaker 2: I think it also touches on whether the black holes
Speaker 2: inherently are different. Are there features to two black holes
Speaker 2: which tell them apart? Because in general relativity, the idea
Speaker 2: is that all you can know about a black hole
Speaker 2: are three different quantities how much mass it has, whether
Speaker 2: it's spinning, and whether it has electrical charge. And to
Speaker 2: say that that's all you can know about a black
Speaker 2: hole means that that's what defines a black hole. So
Speaker 2: in general relativity, two black holes with the same mass, spin,
Speaker 2: and charge really are identical according to that theory.
Speaker 1: From the outside right, I mean, it's basically saying that's
Speaker 1: all you can tell about what's inside a black hole.
Speaker 2: It means those are the only properties of the objects,
Speaker 2: So even on the inside, they would be identical again
Speaker 2: according to general relativity. Important caveat we can get to later.
Speaker 1: But I guess, how can they be exactly identical or
Speaker 1: how can we know or how can the theory know
Speaker 1: that it's identical because inside the black hole maybe things
Speaker 1: are arranged differently.
Speaker 2: We can't know currently because we can't see inside black holes,
Speaker 2: but that doesn't stop the theory from predicting what's there
Speaker 2: and describing what we think is happening. And according to
Speaker 2: general relativity, again big caveat there we can get to
Speaker 2: in a minute. All these black holes, if they have
Speaker 2: the same mass, spin, in charge, really are identical. They
Speaker 2: have the same exact internal structure because they're defined just
Speaker 2: by those three numbers, So there's no whiggle room. There's
Speaker 2: no opportunity for a black hole made of bananas to
Speaker 2: be different from a black hole made of bowling balls
Speaker 2: or squirrels if they have the same mass, spin, and charge.
Speaker 2: That's again according to general relativity, which is predict what's
Speaker 2: inside black holes, though it's not something we've seen.
Speaker 1: I guess what I mean is like a black hole
Speaker 1: is like a sphere right like to us, it has volume,
Speaker 1: and so what does general relativity predict is inside of
Speaker 1: that sphere just a singularity? Like everything just collapses instantly
Speaker 1: or what.
Speaker 2: Well, a black hole that's had time to settle, everything
Speaker 2: will fall towards the singularity. So if things are still
Speaker 2: dynamically falling into a black hole, its state is changing.
Speaker 2: But after a long time. When it settles, then it's
Speaker 2: just defined by these three numbers. And yeah, two black
Speaker 2: holes with the same mass will each have a singularity
Speaker 2: inside them with the same.
Speaker 1: Mass and nothing between the singularity and the event horizon.
Speaker 1: What does general relativity say is between the singularity which
Speaker 1: is at the center, and the event horizon, which is
Speaker 1: the outer shell of the black hole.
Speaker 2: So it depends a little bit on the mass, spin,
Speaker 2: in charge. These kinds of black holes have different internal structures,
Speaker 2: like the simplest kind one with just mass and no spin,
Speaker 2: no charge, or this is the kind most people talk
Speaker 2: about and think about, is just a sphere and in
Speaker 2: the inside you have the singularity and there's nothing else.
Speaker 2: If it's charged or if it's spinning, then the structure
Speaker 2: in the inside is a little bit different, Like you
Speaker 2: don't actually have a singularity if it's spinning, you have
Speaker 2: a ringularity because you need an object that can spin
Speaker 2: and singularities can't. And you can have different kinds of
Speaker 2: horizons inside the black hole or even near the black
Speaker 2: hole on the outside if it's spinning and if it
Speaker 2: has charge.
Speaker 1: Well, that's an interesting concept you just mentioned, which is
Speaker 1: like the settling of a black hole. Now does that
Speaker 1: happen like instantly over billions of years trillions? Does it
Speaker 1: ever happen? Doesn't times stop? Inside of a black hole?
Speaker 2: Nothing happens instantly, right. Relativity describes how there's a maximum
Speaker 2: speed limit to the universe, and so you definitely can't
Speaker 2: have things instantly collapsing into a singularity. It always takes time.
Speaker 2: How much time it takes depends on who you are
Speaker 2: and where you are. Like, if you're outside the black
Speaker 2: hole and you're watching things fall in, you'll actually not
Speaker 2: see them fall in because time slows down so much
Speaker 2: at the event horizon. You'll see them frozen at the
Speaker 2: event horizon. If you are riding that banana into the
Speaker 2: black hole, then you will see yourself past the event
Speaker 2: horizon and you'll fall in, and you'll reach the singularity
Speaker 2: in a finite amount of time. So how long it
Speaker 2: takes depends on the observer. In general relativity, these things
Speaker 2: are very screwy.
Speaker 1: But I guess maybe then the scenario I wonder that
Speaker 1: Matthew's thinking about me, Like, if I have two black holes,
Speaker 1: they have the same mass and energy and spin in
Speaker 1: charge and all that they're identical, But then black hole
Speaker 1: A eats a banana, and black hole b eats a
Speaker 1: bowling ball. Like to us, it takes some time for
Speaker 1: the banana to and bolling bull to make it to
Speaker 1: the center of the black hole. So are those two
Speaker 1: black holes different in the meantime.
Speaker 2: In the meantime they are. Yeah, But if the bowling
Speaker 2: ball and the banana have the same mass, and like
Speaker 2: that's a tiny bowling ball or a huge banana, then
Speaker 2: eventually they do reach steady state, which is just described
Speaker 2: by the mass, spin and charge.
Speaker 1: But could we tell that one aid the banana and
Speaker 1: the other one ate the bowling ball.
Speaker 2: We couldn't, right, Not after they've settled into the singularity exactly.
Speaker 2: According to general relativity, that information is lost. Before that
Speaker 2: information is still within the event horizon. We can't see it,
Speaker 2: but it does still exist within the black hole after
Speaker 2: it's settled into the singularity. According to general relativity, that
Speaker 2: information is gone because the state is perfectly described by
Speaker 2: the mass, spin in charge.
Speaker 4: Mmm.
Speaker 1: So then it's sort of possible for two black holes
Speaker 1: to be different, perhaps, but for us to not be
Speaker 1: able to tell them apart.
Speaker 2: Yeah, that is possible, and that's a transient state.
Speaker 1: Right, Well, black holes are eating all the time, right,
Speaker 1: So black.
Speaker 2: Holes in the real world yet are always eating are
Speaker 2: They're always surrounded by something. There's never a true vacuum.
Speaker 2: There's always a solar wind or particles everywhere. So yeah, absolutely,
Speaker 2: black holes are always eating in real life. In the
Speaker 2: sort of thought experiments we construct, you could imagine a
Speaker 2: black hole surrounded by actually nothing and then you just
Speaker 2: drop a banana into it. But yeah, and the real universe,
Speaker 2: black holes are never surrounded by nothing.
Speaker 1: But I think, as you were saying, this all depends
Speaker 1: on general relativity.
Speaker 2: Yeah, exactly. This is a picture from classical physics that
Speaker 2: says that singularities can exist within black holes, and that
Speaker 2: it matter could be compressed into a tiny dot. That's
Speaker 2: totally incompatible with what we know about the nature of
Speaker 2: reality that is quantum mechanical. Though, when things get really
Speaker 2: really small, like the size of singularities, different rules take
Speaker 2: over and have to be accounted for, rules that general
Speaker 2: relativity ignores. So we don't think singularities actually do exist
Speaker 2: at the heart of any black holes in our universe.
Speaker 2: We think, if black holes are even real, that there's
Speaker 2: some other kind of thing going on, something dictated by
Speaker 2: a different theory of physics, not general relativity, one that
Speaker 2: correctly incorporates the quantum nature of our universe, a theory
Speaker 2: we don't have today, so we can't say what we
Speaker 2: actually think is inside a black hole.
Speaker 1: I think maybe Matthew's question is, like, let's say black
Speaker 1: holes they're all a little bit different inside, depending on
Speaker 1: their density, Like maybe some of them are super dense
Speaker 1: but collass into a singularity, or maybe some do, or
Speaker 1: maybe some are more like uh, let strings every fuzzballs.
Speaker 1: I wonder if they can be different in that way inside,
Speaker 1: but to us from the outside they all look the same.
Speaker 2: It's possible, and it depends on your flavor of quantum gravity.
Speaker 2: If what he's describing is true. There are no classical
Speaker 2: black holes in the universe. They're all some weird quantum version.
Speaker 2: And you're right, there could be a variety, right, There
Speaker 2: could be some fuzzballs and some dark stars and some
Speaker 2: white holes and some other kind of crazy stuff going on.
Speaker 2: And whether we could see the difference on the outside
Speaker 2: also depends on the details of the quantum gravity theory.
Speaker 2: In some scenarios, you can tell what's inside a black
Speaker 2: hole by studying the patterns of the hawking radiation, which
Speaker 2: might be quantum entangled with the details of what's going
Speaker 2: on inside and leaking that information out. There are other
Speaker 2: quantum theories of black holes in which you still can't
Speaker 2: get that information out even though it is inside the
Speaker 2: event horizon. So it depends on your flavor of quantum
Speaker 2: black hole. But it's possible that all these things do
Speaker 2: really exist in our universe.
Speaker 1: Hmmm. It sounds like it sort of depends on what
Speaker 1: you define as a black hole, right, Like, if you
Speaker 1: define it as what a general what relativity calls a
Speaker 1: black hole, then you get one as er. But if
Speaker 1: you just define it as something that has an event
Speaker 1: horizon that doesn't let you look inside, it is possible
Speaker 1: maybe to have different kinds of black holes exactly.
Speaker 2: And remember, not all of these objects even have event horizons.
Speaker 2: When we talk about a black hole, we sort of
Speaker 2: imply an event horizon. But it's possible that some of
Speaker 2: the things out there in the universe that we call
Speaker 2: black holes don't actually have event horizons. We haven't verified
Speaker 2: the event horizon nature of those objects. They're just really
Speaker 2: really small, really really massive, and really really space bendy
Speaker 2: in the way we expect black holes to be, but
Speaker 2: we haven't like zoomed up close and proven that they
Speaker 2: actually have event horizons. And some of these theories don't
Speaker 2: create objects with event horizons.
Speaker 1: But some do, right, Like you could have a dark
Speaker 1: star that does have event horizon.
Speaker 2: Perhaps, yeah, some of them do. It depends on the
Speaker 2: flavor or quantum gravity.
Speaker 1: Hmm, all right, well then so then the answer for
Speaker 1: Matthew is, uh, it depends and we don't.
Speaker 2: Know that summarizes most of physics.
Speaker 1: Yes, it depends that black hole that's in your backyard.
Speaker 2: What it means is that there's still so much to
Speaker 2: learn about the nature of these objects. And the answer
Speaker 2: to the question might not be it's this kind or
Speaker 2: it's that kind, but it's all the kinds. I love
Speaker 2: that possibility.
Speaker 1: Mmm. So it sort of maybe depends on what's actually
Speaker 1: going on, which we don't have a clear theory about.
Speaker 2: And we might not ever know.
Speaker 1: Ever.
Speaker 2: It might be that the universe prevents us from ever
Speaker 2: seeing inside these black holes, or that the information in
Speaker 2: the Hawking radiation doesn't reveal what's inside them. It might
Speaker 2: be that we're not smart enough to figure out the universe.
Speaker 1: Who knows, Boy, I wish you had left the question
Speaker 1: on a more positive note, But it could.
Speaker 2: Be that we figure it all out and then you
Speaker 2: go in ten generations the latest. Daniel and Jorge are
Speaker 2: explaining it all to you on their podcast.
Speaker 1: All right, all right, yeah, that's good. That doesn't leave
Speaker 1: us in a black hole. All right, let's tackle some
Speaker 1: of our other questions. We have questions here about the
Speaker 1: number of neutrinas in the universe and also about what
Speaker 1: it's like to bob up and down on a gravitation wave.
Speaker 1: So let's stick into those. But first let's take a
Speaker 1: quick break. Right we're answering questions from listeners, and our
Speaker 1: next question comes from Sam from British Columbia.
Speaker 3: Hello, Daniel and Jorge, this is Sam from British Columbia
Speaker 3: and thank you for your podcasts and availability to answer
Speaker 3: our questions. It is really appreciated about neutrinos. You always
Speaker 3: mention how many trillions are passing through the Earth every second.
Speaker 3: This got me wondering about how many neutrinos are estimated
Speaker 3: to exist in the universe, as well as proportions for
Speaker 3: the other main particle groups.
Speaker 2: In the standard model.
Speaker 3: It has often estimated that there are ten to the
Speaker 3: eighty particles in the universe. When he asked chat gpt
Speaker 3: for help, I got back that each of the groups
Speaker 3: of leptons, quarks, and bow sounds each were in the
Speaker 3: order of ten to the eighty, and then that there
Speaker 3: were significantly more electrons than neutrinos, and also that there
Speaker 3: were about ten to the eighty of each. I think
Speaker 3: chat gpt once again was confused, and I'm hoping you
Speaker 3: can help unconfuse me.
Speaker 1: Thanks all right, Well, I'm glad that we were his
Speaker 1: second choice for answering questions about the universe.
Speaker 2: Oh man, chat GPT.
Speaker 1: I guess chat gpt is free. I guess you don't
Speaker 1: have to listen to ads d I.
Speaker 2: Think you have to pay for some version of chat GPT.
Speaker 2: No version of it can be relied on to answer
Speaker 2: physics questions. I see, well, you know what they say,
Speaker 2: you get what you pay for. You can do get
Speaker 2: what you paid for.
Speaker 1: It sounds like chat jipt did not answer Sam's question
Speaker 1: or game of an answer that maybe it was confusing.
Speaker 2: Well, it's also not designed to answer physics questions. It's
Speaker 2: designed to generate text which looks like the answers to
Speaker 2: questions it's not designed to do any reasoning, or have
Speaker 2: a model of the universe, or actually think in any way,
Speaker 2: or be accurate or explain things. So I wouldn't rely
Speaker 2: on chat gpt to answer any questions. Yet you could
Speaker 2: say that about anything. Man, your toaster hasn't replaced you yet.
Speaker 1: Well, you know, it's like they say, chat chipet is
Speaker 1: not designed to do basic math, right, Like, if you
Speaker 1: ask it a math question, it may not give you
Speaker 1: the right answer. But I've seen examples of like asking
Speaker 1: Chad Gipt to check using some sort of math toolbox,
Speaker 1: and then it gives you the right answer.
Speaker 2: Yeah, you know a stop clock is right a few
Speaker 2: times a day, right, yeah?
Speaker 1: Yeah, So you could ask chat gipt twice a day
Speaker 1: to go read every physics paper in the universe and
Speaker 1: then come back to you with an answer, which is
Speaker 1: basically what we do in this podcast.
Speaker 2: And it's the wrong tool for the job. You know.
Speaker 2: Its job is to generate text which resembles answers, not
Speaker 2: to reason and think and provide explanations. I don't think
Speaker 2: it'll ever be a good place to ask physics questions.
Speaker 2: I say, I see somedays somebody might actually develop an
Speaker 2: AI which is good at the reasoning and thinking and explaining.
Speaker 2: I'm not ruling that out. I'm pretty sure that will
Speaker 2: happen one day, but large language models won't get there.
Speaker 1: I think what you're saying is that we're the right tools.
Speaker 2: Yes, ask us where we were, just the pair tools,
Speaker 2: just like data on Star Trek.
Speaker 1: Right, there you go, There you go. Maybe the next
Speaker 1: chat GBT should be called Daniel and Cordy Chat DJ.
Speaker 1: All right, well, let's get to Sam's question here. Samon
Speaker 1: wants to know how many neutrinias there are in the universe, right, Like,
Speaker 1: what's a good estimate for the number of neutrinos in
Speaker 1: the universe?
Speaker 2: Such an awesome question because there are so many neutrinos
Speaker 2: in the universe, it's mind boggling.
Speaker 1: Well, there's a lot of everything in the universe, right, Well,
Speaker 1: there's only one me and one you. How do you know.
Speaker 2: Ship a theseus man, if there's another copy of me,
Speaker 2: it's not me.
Speaker 1: Well, there could be one you that has gone through
Speaker 1: the same experiences as you. Wouldn't that be the same Anyways,
Speaker 1: let's get back on track here. It's a big universe.
Speaker 1: Asne wants to know how many neutrinios are Why do
Speaker 1: you think he wants to know how many there are? Like,
Speaker 1: why neutrinos? Why not how many electrons or quarks there
Speaker 1: are in the universe?
Speaker 2: I think because neutrinos give us a window into a
Speaker 2: deeper understanding of what's out there in the universe. Like
Speaker 2: we're made out of quarks and electrons, and that feels like, Oh,
Speaker 2: that's the universe, what's all that made out of? But
Speaker 2: as soon as you realize that our senses are limited
Speaker 2: and that there's so much more going on in the
Speaker 2: universe than the little bits of matter that you and
Speaker 2: I are made out of, it makes you wonder what's
Speaker 2: out there, how much of it is there? And new
Speaker 2: trinos are like the tip of that invisible matter Iceberg.
Speaker 1: I see, Well, how would you answer the question of
Speaker 1: how many new trinos there are?
Speaker 2: Yeah, so it takes a few steps. Basically, you have
Speaker 2: to know how many protons there are in the universe,
Speaker 2: and then you have to try to figure out how
Speaker 2: many neutrinos there are per proton. And it turns out
Speaker 2: that we can do both of those calculations.
Speaker 1: Wait, why do we have to go through protons?
Speaker 2: Because the way we figure out how many new trinos
Speaker 2: there are in the universe is by going back to
Speaker 2: the very very early universe and understanding how photons and
Speaker 2: protons and neutrinos and dark matter all slashed around and
Speaker 2: pushed against each other. It's this plasma soup at the
Speaker 2: very beginning of the universe that reveals the answers to
Speaker 2: all of these questions. From measurements of the cosmic microwave background,
Speaker 2: we can learn a lot about that plasma and how
Speaker 2: it was slashing, and it tells us the answers to
Speaker 2: all of these things. Then, specific ways it tells us
Speaker 2: some ratios allow us to get to these answers.
Speaker 1: Like the beginning of the universe tells you the original
Speaker 1: recipe of the universe kind.
Speaker 2: Of yeah, exactly, And some of that hasn't changed, and
Speaker 2: some of that has changed, and we know how that
Speaker 2: has changed, and we can evolve that through time. But
Speaker 2: it basically starts the machine and tells us how things
Speaker 2: evolve through time.
Speaker 1: But is it even possible to get this answer because
Speaker 1: aren't neutrino's being created, for example, all the time in
Speaker 1: the sun? Like, are new neutrinos being made all the time?
Speaker 2: Yeah? The specific number like to the individual neutrino is
Speaker 2: not very well defined because neutrinos are quantum particles, and
Speaker 2: so they even have probabilities of existing. Like you have
Speaker 2: a certain reaction that might generate neutrinos. Whether it actually
Speaker 2: did or not isn't even determined until it interacts with
Speaker 2: some classical objects. So from a quantum mechanical point of view,
Speaker 2: getting the answer down to like the individual neutrino is
Speaker 2: not technically possible, and even zooming out a little bit
Speaker 2: as you say, there are neutrino factories in the universe
Speaker 2: and neutrinos being annihilated. Neutrinos can be created and destroyed,
Speaker 2: so the number is changing. But it turns out that
Speaker 2: the number of neutrinos being created in roid in the
Speaker 2: universe is really tiny compared to like the huge reservoir
Speaker 2: of neutrinos we already have.
Speaker 1: Well, how do you.
Speaker 2: Know, because we think we understand those processes, and we've
Speaker 2: measured neutrinos that come from space and neutrinos that pass
Speaker 2: through the Earth. Neutrino physics is something we're really starting
Speaker 2: to get a grip on in like the last twenty years.
Speaker 2: So we are a pretty good handle on how many
Speaker 2: neutrinos are out there and how many are being made
Speaker 2: by the Sun. We even see neutrinos generated by crazy
Speaker 2: sources in other galaxies. Neutrino astronomy is something that's really
Speaker 2: come into its own in the last couple of decades.
Speaker 1: And so what's the picture. It's like the Sun is
Speaker 1: making bazillions of neutrinos, but that's very like a drip
Speaker 1: of water compared to like we're swimming in an ocean
Speaker 1: of neutrinos.
Speaker 2: Zechon what you're saying exactly. It's like asking what's the
Speaker 2: volume of the Pacific? Well, you don't really have to
Speaker 2: worry about evaporation and rain because those are tiny details
Speaker 2: relative to massive volume of water there.
Speaker 1: And so then what's the connection to protons? Why do
Speaker 1: we need to know how many protons there are?
Speaker 2: Know how many neutrinos there are per proton. That's a
Speaker 2: measurement we can make back in the very early universe.
Speaker 2: If you wind the universe backwards, we see that it
Speaker 2: gets hotter and denser. Right now, the universe is kind
Speaker 2: of old and cold, very dilute, very chill. But as
Speaker 2: you wind time backwards and you undo the expansion, things
Speaker 2: get very hot and very dense. Back to some early
Speaker 2: state where there were protons and there were photons, and
Speaker 2: there were electrons, and there were also neutrinos zipping about,
Speaker 2: and we can see photons from that moment. This is
Speaker 2: the moment we call the surface of last scattering, when
Speaker 2: the universe became transparent to those photons, so they're still around.
Speaker 2: So we can see a picture of what that early
Speaker 2: universe plasma looked like. It's called the cosmic microwave background radiation,
Speaker 2: and we can see patterns in it. We see wiggles
Speaker 2: and we see waves. Those wiggles and waves are determined
Speaker 2: by how it's slashing, which depends on how many protons
Speaker 2: there are, how many photons there are, how much dark
Speaker 2: matter there is. As you change those fractions, that early
Speaker 2: universe plasma slashed differently because those different pieces all behave differently.
Speaker 1: But even neutrinos were consequential at the beginning of the
Speaker 1: universe because I thought neutrinos were basically massless and they're
Speaker 1: ghostly and they they don't really interact with anything much.
Speaker 1: Isn't there like a wide range of neutrino proportions that
Speaker 1: could have been there at the beginning of the universe.
Speaker 2: Yeah. Absolutely. Neutrinos don't interact very much, but they do
Speaker 2: have energy, and so they affect the energy density of
Speaker 2: the universe, which changes its expansion. And because neutrinos are
Speaker 2: very very light, they sort of fall into the same
Speaker 2: category as photons. Back in the early universe, everything that
Speaker 2: was moving almost at the speed of light or at
Speaker 2: the speed of light gets counted kind of as radiation.
Speaker 2: Remember we talked about this once, and stuff that's moving
Speaker 2: very very slowly gets counted as matter. And so things
Speaker 2: that are moving as radiation do affect the expansion of
Speaker 2: the universe because they affect the energy density in this
Speaker 2: complicated way. So you're right, the neutrinos are weak, but
Speaker 2: they still have energy and that affects the old overall
Speaker 2: balancing of these equations in general relativity.
Speaker 1: There's stills a piece of the pot.
Speaker 2: Yeah, exactly. And it turns out there's a huge number
Speaker 2: of them, so they have a pretty big influence.
Speaker 1: Oh, how big of a number, Like if you had
Speaker 1: a pie chart of the universe at the beginning in
Speaker 1: the Big Bang, how big is the neutrino slice.
Speaker 2: Yeah, so you wouldn't even be able to see the
Speaker 2: protons on that pie chart because there are approximately one
Speaker 2: billion neutrinos for every proton.
Speaker 1: Well in terms of quantity, but in energy, how big
Speaker 1: of a slice is it there?
Speaker 2: The numbers are much more closely balanced. There are many
Speaker 2: fewer protons, but protons have a huge mass compared to
Speaker 2: neutrinos that have almost no mass. On the other hand,
Speaker 2: the neutrinos have a lot more kinetic energy. Right they're
Speaker 2: moving really really fast, They're almost at the speed of light,
Speaker 2: so the energy is there are much better balanced that
Speaker 2: are in the same order of magnitude. The numbers aren't
Speaker 2: exactly determined, but the original question was about the number
Speaker 2: of neutrinos in the universe, and so there we need
Speaker 2: the number ratio, and the cosmic microwave background radiation tells
Speaker 2: us that there are like three hundred and thirty million
Speaker 2: neutrinos per cubic meter of space back then, and there
Speaker 2: was less than one proton per cubic meter, so the
Speaker 2: ratio is about a billion I.
Speaker 1: See, so neutrino's were a pretty significant slice of the universe,
Speaker 1: but in terms of quantity, like number of neutrinos because
Speaker 1: they're so small at night that the number of them
Speaker 1: dwarfs the number of protons around us exactly.
Speaker 2: So there's this incredible ocean of neutrinos back in the
Speaker 2: early universe and still today. Like the density of neutrinos
Speaker 2: has dropped because the universe expands and everything gets more
Speaker 2: dilute except for dark energy, but most of those neutrinos
Speaker 2: are still around. It's called the cosmic neutrino background, and
Speaker 2: it's something we're searching for in neutrino experiments.
Speaker 1: Does it depend still on the number of protons? Is
Speaker 1: it the same ratio like three hundred and thirty million
Speaker 1: to one or billion to.
Speaker 2: One, depends a little bit what you count as a proton.
Speaker 2: Like some of those protons go on to make helium.
Speaker 2: There's still protons in there, but like now we call
Speaker 2: them helium instead of protons or hydrogen. But most of
Speaker 2: those protons are still around, and most of those neutrinos
Speaker 2: are still around, and because they're both matter, they both
Speaker 2: get diluted in the same way as the universe expands,
Speaker 2: and so their ratio is approximately the same.
Speaker 1: Then to get account of the number and neutrinos, we
Speaker 1: need a count of the number of protons, So how
Speaker 1: many protons are there in the universe.
Speaker 2: So in the observable universe, we don't know what's in
Speaker 2: the full universe right past where we can see. We
Speaker 2: know the density of protons, which is about a fifth
Speaker 2: per cubic meter, and we know roughly the volume of
Speaker 2: the observable universe, which is like ten to the eighty
Speaker 2: cubic meters or so, and that means around ten to
Speaker 2: the seventy nine protons in the observable universe. That's ten
Speaker 2: with seventy nine zeros. It's not even like a name
Speaker 2: for that.
Speaker 1: Number, Sure there is, we can make one.
Speaker 2: Up, right, there will be soon.
Speaker 1: What's the number bananion?
Speaker 2: Coincidentally, there's exactly one bananion of protons in the universe.
Speaker 1: Oh my gosh, such a coincidence.
Speaker 2: Which means that there's a billion bananians of neutrinos in
Speaker 2: the universe, because it's about a billion neutrinos per.
Speaker 1: Proton, So ten to the what eighty eight.
Speaker 2: About ten to the eighty eight neutrinos in the observable universe.
Speaker 1: Observable universe, but the observable universe is getting bigger every day. Right,
Speaker 1: So that number is going up.
Speaker 2: Actually depends a little bit how you think about distance.
Speaker 2: The universe is expanding faster than the speed of light,
Speaker 2: so the fraction of stuff in the universe we can
Speaker 2: see is actually shrinking, right, And eventually a lot of
Speaker 2: stuff is going to fall outside of our horizon. So
Speaker 2: the number of particles in the observable universe is actually decreasing.
Speaker 1: WHOA, the universe is its outgrowing how far we can see.
Speaker 2: Yeah, exactly. The universe is expanding faster than our horizon is,
Speaker 2: so particles are disappearing from the observable universe. That's another
Speaker 2: reason why the number is not fixed.
Speaker 1: Well, it may not even be fixed, right, Like, maybe
Speaker 1: the universe is infinite, in which case there's maybe an
Speaker 1: infinite number of neutrinos.
Speaker 2: Yeah, exactly. In that case, you could still measure the
Speaker 2: density of neutrinos like three hundred and thirty million per
Speaker 2: cubic meter, but the total number in the whole universe
Speaker 2: would be infinite. If the universe is infinite, and if
Speaker 2: the universe beyond a horizon is similar to the bits
Speaker 2: that we see here, could be that what's beyond the
Speaker 2: horizon is very different, right, And then we live in
Speaker 2: a weird patch of the universe.
Speaker 1: Right right, It depends and we don't know, is what
Speaker 1: you're saying. But what do you think is the ratio
Speaker 1: of like in the universe, the ratio between neutrinos and Daniels.
Speaker 1: Is it infinite to one or is there a fixed number?
Speaker 2: That's the question philosopher has been wondering about for thousands
Speaker 2: of years, and we're not going to answer it today
Speaker 2: on the podcast.
Speaker 1: That's right. We don't have the time. That's why we're
Speaker 1: not answering.
Speaker 2: That's right, exactly. No, I think if there are other
Speaker 2: Daniels out there, there's still not me because I'm not
Speaker 2: experiencing them, even if they think that there Daniel. I'm
Speaker 2: experien think this one, which makes this one different, which
Speaker 2: makes me unique. I'm only experiencing one Daniel.
Speaker 1: Unless they're having the exact same experience you are, in
Speaker 1: which case, in which case, there the outside can't tell
Speaker 1: the difference.
Speaker 2: But we can from inside, right inside the Daniel horizon,
Speaker 2: you can tell which Daniel you are.
Speaker 1: But your feeling of uniqueness is the same feeling of
Speaker 1: unique is the other Daniel's having.
Speaker 2: Yeah, that's right, But I'm only feeling my feeling of uniqueness.
Speaker 2: I'm not feeling bears. Oh, I see.
Speaker 1: So to you, there's only one Daniel, yeah, but maybe
Speaker 1: to someone outside of the universe there is an infinite
Speaker 1: number of Daniels.
Speaker 2: Yeah. And it means and we don't know, And to
Speaker 2: me is all that matters, because I'm the only consciousness
Speaker 2: I'm actually aware of in the universe.
Speaker 1: But I'm not asking what matters to you. I'm wondering
Speaker 1: what matters to me, Daniel.
Speaker 2: I don't know if you're even real.
Speaker 1: So that's right, We're all in them some AI's imagination.
Speaker 1: All right, Well, I think that answers the question for Sam.
Speaker 1: The estimate of the number of neutrinos in the observable
Speaker 1: universe is ten to the eighty eight neutrinos plus or
Speaker 1: minus ten to the what eighty seven.
Speaker 2: Seven pluster minus infinity.
Speaker 1: Probably there's our pleasure minus infinity. All right, Well, let's
Speaker 1: get to our last question of the episode, which is
Speaker 1: about gravitational waves and can you serve one? So let's
Speaker 1: get into that, but first let's take another quick break.
Speaker 1: All right, Our last question of the day comes from
Speaker 1: Klai wants to know about gravitational waves.
Speaker 5: Howdy Daniel and Jorge. I was wondering how would feel
Speaker 5: to be hit by a gravitational wave? We have detected
Speaker 5: infinitely weak waves from Earth, but imagine if we were
Speaker 5: close to two black holes revolving around each other and
Speaker 5: eventually colliding and merging. How would it feel to get
Speaker 5: hit by a gravitational wave? And would it be the
Speaker 5: same as a wave? And finally, would your organs be damaged?
Speaker 1: Interesting question. It sounds like Clay is planning a trip. Perhaps.
Speaker 2: I think Klay wants to experience the universe, wants to
Speaker 2: feel gravitation waves, not just read about it online.
Speaker 1: Well, I think one of the things is that, first
Speaker 1: of all, we're all experiencing gravitation waves right now.
Speaker 2: Right, Yeah, that's true. Gravitational waves are everywhere. They fill
Speaker 2: the universe because they're generated anytime any mass is accelerated.
Speaker 2: So you're in orbit, you're generating gravitational waves. You get
Speaker 2: out of bed, you're generating gravitational waves. Gravitational waves are everywhere, right.
Speaker 1: We're experiencing them. We're generating them like if a car
Speaker 1: accelerates in front of me, technically gonna feel or I'm
Speaker 1: going to experience the gravitational wave generated by the car.
Speaker 2: Right, It's very hard to feel these things because they're very,
Speaker 2: very gentle. Remember that gravity is like the dominant force
Speaker 2: and the structure of the universe, but it's also the
Speaker 2: weakest force, if you even call it a force, so
Speaker 2: much weaker than the forces that hold your body together
Speaker 2: for example.
Speaker 1: Right, they're super mellow, hard to detect, but we can
Speaker 1: detect some of the ones that come from deep in
Speaker 1: outer space, that come from black holes or heavy things
Speaker 1: circling each other and then colliding.
Speaker 2: Exactly. The way to detect gravitational waves is to look
Speaker 2: for extremely loud sources of them, things that make very
Speaker 2: dramatic gravitational waves. And so two black holes, which are
Speaker 2: two enormous masses orbiting each other very very quickly just
Speaker 2: before they collide, are very loud sources of gravitational waves.
Speaker 2: So even though we're very far from them, we can
Speaker 2: be like a billion light years away, we can still
Speaker 2: detect those gravitational waves here on Earth with super sensitive detectors.
Speaker 1: Right here on Earth. By the time that they get
Speaker 1: to us, they're super weak because I guess, like a
Speaker 1: ripple in a laketational waves get weaker as they expand
Speaker 1: right from their source.
Speaker 2: Yeah, as you get further from the source, they get
Speaker 2: weaker and weaker.
Speaker 1: Right, And as you said, the ones we're detecting now
Speaker 1: with LIGO, which is the big physics instrument we have
Speaker 1: here on Earth, those happen billions of light years away.
Speaker 1: And I think the Khalist question is, like, what if
Speaker 1: you're closer to that source of gravitational waves, Like, what
Speaker 1: if you're right next to those two black holes glide in?
Speaker 1: What would it feel like to have this giant gravitation
Speaker 1: wave pass three?
Speaker 2: Yeah, it's a really cool question to think about it.
Speaker 2: I think we should like zoom in on what happens
Speaker 2: first to like individual particles in your body, and then
Speaker 2: think about what that would feel like.
Speaker 1: There's a way. Wait, but the scenario is how close
Speaker 1: am I to these gravitational waves?
Speaker 2: So imagine we're just like a few tens of thousands
Speaker 2: of kilometers away from these two black holes that are
Speaker 2: orbiting each other.
Speaker 1: Aren't black holes usually bigger than a few tens of
Speaker 1: thousands of kilometers or are you imagining like two small ones?
Speaker 2: Well, the kind of collisions we've seen are between black
Speaker 2: holes that have like thirty to fifty solar masses, and
Speaker 2: those have an event horizon radius of like one hundred
Speaker 2: kilometers or less, So if you're thirty thousand kilometers away,
Speaker 2: you're definitely not inside the event horizon.
Speaker 1: Okay, so these are pretty small black holes.
Speaker 2: Yeah, but these are the kinds of black holes we've
Speaker 2: been able to see collide.
Speaker 1: Ooh, all right, so then we're a few tens of
Speaker 1: thousands of kilometers away from these two black holes smashing
Speaker 1: into each other exactly.
Speaker 2: And on a human, if you're like thirty fifty thousand
Speaker 2: kilometers away from two black holes that have like the
Speaker 2: mass of thirty or fifty times the sun, then you're
Speaker 2: going to feel what's called a strain of about one millimeter.
Speaker 2: The strain is how much your body is getting squeezed
Speaker 2: by the gravitational wave. And this is what we measure
Speaker 2: also here on Earth with LEGO, we have these innerferometers,
Speaker 2: these very long laser legs that get squeezed and lengthened
Speaker 2: as the gravitational wave passes by. The ones here on
Speaker 2: Earth are so faint that the measure strains of like
Speaker 2: one times ten to the negative twenty one, which means
Speaker 2: that like the two mile leg of the inferometer gets
Speaker 2: shorter by that factor. It's a really really tiny factor.
Speaker 1: But unless how much like space is being stretched or compressed, right, Like,
Speaker 1: not necessarily something in space, right, because it's something in
Speaker 1: space is sort of holing on to itself. But you're
Speaker 1: talking about the stretching of space itself.
Speaker 2: Yeah, the changing of the distance between two particles. For example,
Speaker 2: So imagine you have two particles and you're a few
Speaker 2: tens of thousands of kilometers away from these black holes
Speaker 2: that are e merging, and they're generating gravitational waves. What's
Speaker 2: going to happen is they're going to change the distance
Speaker 2: between the two atoms. Right, So, for example, that the
Speaker 2: distance gets longer than those two atoms, if they were
Speaker 2: like bound together somehow, then they're going to feel an
Speaker 2: attractive force to pull them back to where they were
Speaker 2: in equilibrium. If the gravitational wave is very slow, they're
Speaker 2: going to be able to basically stain in equilibrium and
Speaker 2: nothing really happens. But if the gravitational frequency is high,
Speaker 2: if the sort of squeezing and pulling and pushing is fast,
Speaker 2: they'll effectively feel a force and they might start to
Speaker 2: oscillate back and forth. That's kind of what happens in Lego.
Speaker 1: Like the stretching of space is kind of like how
Speaker 1: much space wants to stretch you.
Speaker 2: Yeah, the distance between those two particles or the two
Speaker 2: mirrors in Lego gets longer or shorter based on the
Speaker 2: gravitational wave. But then the interaction between the two particles,
Speaker 2: or the structural strength of the thing, whatever, has a
Speaker 2: natural length that it wants to be at, so to
Speaker 2: try to return to that natural length. Like if you
Speaker 2: imagine a spring between these two particles, you pull them apart, well,
Speaker 2: the spring is going to pull them back.
Speaker 1: Together, right, So then you're saying, like, if I'm a
Speaker 1: few tens of thousands of kilometers from these black holes,
Speaker 1: and I would feel about a one millimeter stretch in
Speaker 1: my body, or space would want to stretch my body
Speaker 1: about one millimeter mm hmm.
Speaker 2: And based on the frequency, you're going to get shaken
Speaker 2: by one millimeter. It's not like you just get pulled
Speaker 2: by one millimeter in one direction and then you stay there.
Speaker 2: A gravitational wave is a wave. It's oscillating, and depending
Speaker 2: on the frequency, if it's like a fast wave or
Speaker 2: a slow wave, it's going to shake you at that speed,
Speaker 2: so it might like pull you in one direction and
Speaker 2: then squeeze you in that direction and pull you in
Speaker 2: the other direction. So there's this pulling, the stretching, and
Speaker 2: the squeezing. So right now we're talking about the amplitude
Speaker 2: about one millimeter, but the frequency of that is also important,
Speaker 2: and that depends on the orbits of these black holes.
Speaker 2: How many times are they passing around each other. That
Speaker 2: determines the frequency of this gravitational wave. If you're nearby
Speaker 2: these black holes, you're basically going to get shaken from
Speaker 2: the inside.
Speaker 1: Right, And you're saying kind of depending on the frequency,
Speaker 1: it might be dangerous or not. Like if it was
Speaker 1: shaking really slowly, you probably your body can probably adjust
Speaker 1: to that shaking. But if it's shaking super fast, then
Speaker 1: it might scramble your insides.
Speaker 2: You might scramble your insides. You might also experience it
Speaker 2: in a weird way, like it might be like being
Speaker 2: at a concert. Sound waves at a concert also shake
Speaker 2: your body and you experience them as sound. If you're
Speaker 2: out in space near two black holes, you might literally
Speaker 2: hear the gravitational waves because like the drums in your
Speaker 2: ear will get shaken.
Speaker 1: Whoa as put everything else in your body.
Speaker 2: As would everything else, Just like at a concert. Right
Speaker 2: when you're in the moshpit at that concert, your toes
Speaker 2: are getting shaken, even though your ears are the only
Speaker 2: ones actually transmitting sound to your brain. The same way
Speaker 2: a gravitational wave can be squeezing and pulling on your
Speaker 2: whole body, but your ears might be the only ones
Speaker 2: picking it up.
Speaker 1: I've never been in a moshpit, but I'll take your
Speaker 1: word for it, so you might feel it. But is
Speaker 1: it dangerous? Like if it's high frequency enough, and these
Speaker 1: things are pretty high frequency by the time they smash together,
Speaker 1: it's like super high frequency, right.
Speaker 2: Yeah, they can get to be very high frequency. And
Speaker 2: actually the frequency they experience is even higher than we
Speaker 2: observe because there's gravitational time dilation. These black holes, of
Speaker 2: course have super high curvature, and now one black hole
Speaker 2: is near another one, it's experiencing the gravitational time dilation
Speaker 2: of that black hole, so time is super slowed down.
Speaker 2: So what we're observing is the slow down gravitational wave
Speaker 2: being emitted by these event horizons. That's already taken into account.
Speaker 2: If it wasn't, then the frequency would be much much higher.
Speaker 1: Well, I guess from what we know of these smashing
Speaker 1: black holes or the ones we've seen, then the frequency
Speaker 1: we've seen, and how fast there actually are closer to
Speaker 1: the source, would they actually kill you at this distance?
Speaker 1: Like at some point they'll start to rip apart the
Speaker 1: bonds between the proteins in your body, right, or you know,
Speaker 1: it'll basically scramble your brain.
Speaker 2: I don't think I can say. It depends a lot
Speaker 2: on the internal biological friction, like how much energy is
Speaker 2: actually going to get absorbed, and how squishy your body is,
Speaker 2: how resilient it is, depends a lot on the exact
Speaker 2: kind of tissue. I think all I can do is
Speaker 2: treat your body as a sphere with ears and say
Speaker 2: you'll probably hear it happening.
Speaker 1: But you can probably make that calculation, right, Like you
Speaker 1: can calculate this spignification point of a black hole, right,
Speaker 1: like the point at which it would actually tear you
Speaker 1: apart falling into a black hole. You can probably do
Speaker 1: that for gravitational wave, right.
Speaker 2: Yeah, But the energy that gets absorbed depends on this
Speaker 2: internal friction. Like if there's no internal friction to your object,
Speaker 2: it can get squeezed and squished and then be totally unharmed.
Speaker 2: So how much energy is deposited, how much damage is
Speaker 2: done depends entirely on the internal friction of that object.
Speaker 2: It's not just dependent on the tidal forces.
Speaker 1: Right right, But I imagine, I mean, we don't have
Speaker 1: to do it now, or there's no pressure for you
Speaker 1: to come up with an answer. But like, if you
Speaker 1: could make the calculation for like a typical brain, what
Speaker 1: are some of the maximum accelerations a brain can withstand
Speaker 1: before it turns into you know, mush, and you can
Speaker 1: maybe backtrack to find what kind of frequency of gravitation
Speaker 1: waves would kill you.
Speaker 2: Yeah, probably somebody who knows something about the brain could
Speaker 2: figure that out.
Speaker 1: What do we know about brains? We just use them.
Speaker 2: I'm going to guess the answer is it depends, and
Speaker 2: we don't know exactly.
Speaker 1: You read my brain. That's exactly what I was.
Speaker 2: Thinking, exactly. I just got a gravitational wave idea into
Speaker 2: my brain.
Speaker 1: But again, I feel like this is just firm standing
Speaker 1: tens of thousands of kilometers away. May you say, maybe
Speaker 1: we might survive this. I don't know, because don't these
Speaker 1: things go pretty high frequency? Even a one millimeter strain
Speaker 1: might be enough to mois your brain.
Speaker 2: One milimeter strain is pretty big, so I think it
Speaker 2: might be enough. I mean, I think one millimeter strain
Speaker 2: is much more than you ever experienced at a concert.
Speaker 2: Even very very high intensity sound waves don't actually like
Speaker 2: move the molecules in your body by a millimeter. That's
Speaker 2: a pretty huge displacement. And you've got lots of really
Speaker 2: sensitive things inside your body that are much smaller than
Speaker 2: one millimeter, So one millimeters squeezing and stretching could totally
Speaker 2: destroy like really sensitive little biomachineries.
Speaker 1: So smash bit, not moshpit, like your brain gets washed.
Speaker 2: Yeah, I think it might be like being in a blender.
Speaker 1: Great, then I imagine if you get closer to these
Speaker 1: circling black holes and it just gets more dangerous, right,
Speaker 1: because then the waves could get much more intense.
Speaker 2: Exactly, the amplitude of the waves just grows as you
Speaker 2: get closer. The strain gets larger and larger.
Speaker 1: What if you're just a thousand kilometers away, how big
Speaker 1: would the strain be.
Speaker 2: Well, it goes like one over r a little, which
Speaker 2: is a little bit weird, And so a thousand million
Speaker 2: three times closer would be thirty times if you're like
Speaker 2: thirty or ten times closer. If you're ten times closer,
Speaker 2: it's going to be ten times as.
Speaker 1: Strong, times times ten to the three. No, I mean
Speaker 1: a q because because your are went down a tenth,
Speaker 1: So then doesn't the intensity go up by a queue?
Speaker 2: The strain goes like one over r oh linear? You
Speaker 2: sure it's inverse linear? Yeah?
Speaker 1: Oh, it's linear, all right, So then you would experience
Speaker 1: it a one centimeter strain.
Speaker 2: Yeah, ten times closer you get one centimeter strain.
Speaker 1: Oh wait, yeah, that would be a lot.
Speaker 2: That would definitely be a lot. CLI's asking how would
Speaker 2: it feel to get hit by a gravitational wave? Would
Speaker 2: your organs be damaged? It depends a lot on the
Speaker 2: distance you get close enough, it could definitely scramble you. You
Speaker 2: get not too close, then you could probably hear it,
Speaker 2: like physically hear it without being destroyed. But I don't
Speaker 2: know exactly where that line is, and I don't recommend
Speaker 2: you figure it out.
Speaker 4: Mmmm.
Speaker 1: That's right. Keep it a thought experiment, Keep it a
Speaker 1: brain experiment to save your brain. All right. Well, I
Speaker 1: think that answers all of our questions. Some pretty interesting
Speaker 1: ideas here. Overall, the picture is that the universe is
Speaker 1: still mysterious. There's a lot we don't know, and there's
Speaker 1: still a lot of questions we can ask about it
Speaker 1: for us to explore.
Speaker 2: But we love that you ask these questions, and we
Speaker 2: love trying our best to answer them. We don't always
Speaker 2: know the answer. That's sort of the game of physics,
Speaker 2: figuring out where the edge of knowledge is and trying
Speaker 2: to push it forward a tiny little.
Speaker 1: Bit at least. That's one of the games one Daniel
Speaker 1: can play.
Speaker 2: What can we figure out if we have even more Daniels.
Speaker 1: All right, well, we hope you enjoyed that. Thanks for
Speaker 1: joining us. See you next time.
Speaker 2: For more science and curiosity, come find us on social
Speaker 2: media where we answer questions and post videos. We're on Twitter, Discorg, Insta,
Speaker 2: and now TikTok. Thanks for listening, and remember that Daniel
Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio.
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