Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions 49: Black Holes, Neutrinos and Gravitational waves!

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Listener Questions 49: Black Holes, Neutrinos and Gravitational waves! · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Daniel, is it true that every electron is identical?
• 0:12
  Speaker 2: Well, they all do have the same mass and the
• 0:15
  Speaker 2: same charge, Like exactly, yeah, we think so.
• 0:19
  Speaker 1: Isn't that weird? Why don't you expect them to be
• 0:21
  Speaker 1: a little bit different each one.
• 0:23
  Speaker 2: It's kind of exactly not weird. It means that no
• 0:26
  Speaker 2: electrons are weird because they are all the same.
• 0:29
  Speaker 1: I don't know, man, that's a bit wooky. Like if
• 0:33
  Speaker 1: everyone in your neighborhood looked the same, wouldn't that be weird?
• 0:37
  Speaker 2: I mean, I live in Orange County, so that's kind
• 0:40
  Speaker 2: of what most people in the neighborhood are going for.
• 0:43
  Speaker 1: Everyone's going for that scruffy physicist.
• 0:45
  Speaker 2: Look more like plastic surgery face and beige housing.
• 0:50
  Speaker 3: Well.
• 0:50
  Speaker 1: I didn't want to say anything, but yeah, I do
• 0:51
  Speaker 1: feel like you need a facelift in or at least
• 0:54
  Speaker 1: a physics lift. Hi. I'm jorm At, cartoonist and the
• 1:12
  Speaker 1: author of Oliver's Great Big Universe.
• 1:14
  Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor
• 1:16
  Speaker 2: at UC Irvine, and I'm proud of being one of
• 1:19
  Speaker 2: a kind.
• 1:19
  Speaker 1: But what kind is that? Daniel?
• 1:21
  Speaker 2: That's the quiet that you. The pride might depend On. Mm, yeah,
• 1:26
  Speaker 2: I define my kind man. There's nobody else like me. M.
• 1:30
  Speaker 1: How do you know, though, have you met everyone who's
• 1:33
  Speaker 1: ever existed? What if there was a Daniel with your
• 1:36
  Speaker 1: exact same DNA that you know, lived two hundred years
• 1:40
  Speaker 1: ago or could be living right now.
• 1:41
  Speaker 2: It's possible, but they wouldn't have the same experiences. I
• 1:44
  Speaker 2: have actually met another Daniel Whitson. He's an artist in
• 1:48
  Speaker 2: the UK and quite accomplished.
• 1:50
  Speaker 1: Ooh are you jealous?
• 1:54
  Speaker 2: Am I jealous of the artist lifestyle?
• 1:56
  Speaker 3: Oh?
• 1:56
  Speaker 2: So many directions to go with that?
• 2:01
  Speaker 1: What was that like? I don't think I've ever met
• 2:02
  Speaker 1: a horhe Cham yet, but I think one exists somewhere
• 2:06
  Speaker 1: in Indonesia.
• 2:06
  Speaker 2: Maybe isn't there another one who has the Twitter handle
• 2:10
  Speaker 2: at hohorhey.
• 2:11
  Speaker 1: Cham somebody got that Twitter handle. I don't know if
• 2:13
  Speaker 1: it is horri ha Jam or not, but I'm waiting
• 2:16
  Speaker 1: for the blackmail email. Mm.
• 2:18
  Speaker 2: Yeah, well, at least a digital copy of you exists.
• 2:21
  Speaker 1: Or maybe I opened it years ago, but I forgot
• 2:23
  Speaker 1: the password and the email I associated it with, so
• 2:27
  Speaker 1: I don't know. Maybe I am my other meat.
• 2:30
  Speaker 2: Yeah. Maybe we're old enough that younger versions of us
• 2:33
  Speaker 2: are like alien minds.
• 2:34
  Speaker 1: Oh wait, wouldn't that make you an alien?
• 2:39
  Speaker 2: I think we're all still struggling to know ourselves.
• 2:41
  Speaker 1: Right, well, we might all be aliens, right that Isn't
• 2:44
  Speaker 1: there a theory that maybe life came to Earth from Mars.
• 2:48
  Speaker 2: There is a theory like that called panspermia, that life
• 2:51
  Speaker 2: may have originated somewhere else in the universe and then
• 2:54
  Speaker 2: transported microbially hidden inside asteroids. It's a possibility all immigrants,
• 3:01
  Speaker 2: kind of.
• 3:02
  Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain
• 3:04
  Speaker 1: the Universe, a production of iHeartRadio in.
• 3:07
  Speaker 2: Which we do our best to digest this alien universe
• 3:10
  Speaker 2: to explain all of the bizarre and amazing effects we
• 3:13
  Speaker 2: see out there in terms of little mathematical stories that
• 3:16
  Speaker 2: your mind and my mind and Jorge's mind can actually
• 3:19
  Speaker 2: understand that we can talk about and digest and explain
• 3:23
  Speaker 2: to you.
• 3:23
  Speaker 1: That's right, because it is a pretty vast universe, and
• 3:26
  Speaker 1: it's also pretty weird, full of unexplained phenomenon, unanswered questions,
• 3:30
  Speaker 1: and potentially other versions of you out there.
• 3:33
  Speaker 2: Raising all sorts of interesting philosophical questions like what does
• 3:37
  Speaker 2: it mean to have an identical copy? And when you
• 3:39
  Speaker 2: step into a transporter on Star Trek. Is it making
• 3:41
  Speaker 2: a copy or actually transporting you?
• 3:44
  Speaker 1: And what if, like there's another Jorge and another Daniel
• 3:47
  Speaker 1: and they start a podcast. Can we sue them technically
• 3:52
  Speaker 1: or maybe just retiring and give them the feat?
• 3:57
  Speaker 2: Yeah, maybe it's time for the next generation, right.
• 4:00
  Speaker 1: The new Daniel and Jorge explain the universe? Or Daniel
• 4:03
  Speaker 1: and Horry explained the universe the next generation?
• 4:06
  Speaker 2: Exactly? Yeah, one of us is Jean Luke and the
• 4:08
  Speaker 2: other one is Riker.
• 4:11
  Speaker 1: Wait wait, wait your name comes first, as I mean,
• 4:12
  Speaker 1: I'm number two?
• 4:14
  Speaker 2: Make it so? Okay?
• 4:16
  Speaker 1: Can I just beque? Like, if I had to pick
• 4:19
  Speaker 1: a character from the next generation, I would pick Q.
• 4:23
  Speaker 2: Really not Data. Data might be the smartest one.
• 4:26
  Speaker 1: A smart than Q can do anything in time and space.
• 4:30
  Speaker 2: Q has no rules, so it doesn't really count exactly exactly,
• 4:34
  Speaker 2: So you basically you want to be God, you're.
• 4:36
  Speaker 1: Saying, I mean, who doesn't, come on, Q.
• 4:42
  Speaker 2: Has so much responsibility. Every child who's dying of cancer.
• 4:45
  Speaker 2: That's Q's fault, is it?
• 4:47
  Speaker 1: Is it?
• 4:47
  Speaker 2: Really? If you had the power to save a child
• 4:50
  Speaker 2: and you didn't, then yeah, I think you're kind of responsible. Boy.
• 4:54
  Speaker 1: That's a lot of gud killed.
• 4:56
  Speaker 2: That's why I'd rather be data.
• 5:00
  Speaker 1: Do you want to be data or be data?
• 5:03
  Speaker 2: Hmm, Yeah, that's a good question. I actually just want
• 5:05
  Speaker 2: to harness data's computing powers to solve mysteries of the universe. Yeah.
• 5:09
  Speaker 1: That's a lot of makeup to put on every data.
• 5:11
  Speaker 2: It's pretty heavy.
• 5:13
  Speaker 1: Yeah, but anyways, welcome to our podcast. We also like
• 5:18
  Speaker 1: to answer questions, not just talk about the answers that
• 5:21
  Speaker 1: physicists have found. We also like to think about questions
• 5:23
  Speaker 1: about the universe.
• 5:24
  Speaker 2: Because everybody's got questions. I've got questions, You've got questions.
• 5:28
  Speaker 2: Everybody who looks up at the night sky and wonders
• 5:30
  Speaker 2: how it all works, or stares down between their toes
• 5:32
  Speaker 2: and wants to understand the tiniest particles is yearning to
• 5:35
  Speaker 2: understand how the world works, and that means asking questions.
• 5:39
  Speaker 2: And on this podcast we answer questions at the edge
• 5:42
  Speaker 2: of knowledge, those pose by physicists and those pose by listeners.
• 5:46
  Speaker 2: So if you have questions about the nature of the
• 5:48
  Speaker 2: universe or some explanation you've heard somewhere that didn't quite
• 5:51
  Speaker 2: make sense to you, write to us to questions at
• 5:54
  Speaker 2: Danielandjorge dot com. We really do. Right back to all
• 5:57
  Speaker 2: of our listeners.
• 5:58
  Speaker 1: Yeah, we're all curious about how the universe works, why
• 6:01
  Speaker 1: we're in it, and how it's all put together. Although
• 6:03
  Speaker 1: I'm not exactly curious about the particles in your toes
• 6:06
  Speaker 1: or anyone's toes. Maybe we'll leave that part out of
• 6:10
  Speaker 1: our questions.
• 6:11
  Speaker 2: Wow, limits to your curiosity. That's disappointing.
• 6:14
  Speaker 1: Yeah, I think there should be limits to anyone's curiosity.
• 6:19
  Speaker 1: But yeah, we like to answer questions here on the
• 6:22
  Speaker 1: podcast and plans from listeners, and so thanks to everyone
• 6:24
  Speaker 1: who sent their questions in.
• 6:25
  Speaker 2: Often I'll just write back, but sometimes we choose questions
• 6:28
  Speaker 2: to answer on the podcast because we think lots of
• 6:31
  Speaker 2: people will want to hear the answers.
• 6:32
  Speaker 1: And so today on the podcast, we'll be tackling listener
• 6:40
  Speaker 1: questions number forty nine. What are we gonna do when
• 6:43
  Speaker 1: we hit fifty, Daniel, We're gonna have a mid podcast
• 6:45
  Speaker 1: live crisis.
• 6:46
  Speaker 2: We're gonna have a nice cake with fifty on it,
• 6:48
  Speaker 2: and we're gonna fall asleep before the end of the.
• 6:49
  Speaker 1: Party and then burn your house down.
• 6:51
  Speaker 2: What it's gonna be virtual, of course, but.
• 6:56
  Speaker 1: Yeah, we're answering listener questions here today and we have
• 6:59
  Speaker 1: some awesome questions here from our listeners. There's one about
• 7:03
  Speaker 1: black hole identity, there's one about neutrino and how many
• 7:06
  Speaker 1: there are in the universe. And we also have a
• 7:09
  Speaker 1: question about what it's like to serve a gravitational wave
• 7:13
  Speaker 1: and what happens when you wipe out, Like where do
• 7:15
  Speaker 1: you fall if it's a gravitational wave? But let's jump
• 7:19
  Speaker 1: right in. Our first question comes from Matthew, who comes
• 7:22
  Speaker 1: from Barry, Ontario.
• 7:24
  Speaker 4: Hello, Daniel and Jorge. This is Matthew from Barry, Ontario
• 7:28
  Speaker 4: up here in Canada, and like many of your listeners,
• 7:30
  Speaker 4: I spend a bit of time thinking.
• 7:32
  Speaker 1: About black holes.
• 7:34
  Speaker 4: While I understand that it is impossible for us to
• 7:36
  Speaker 4: see what lurks beyond the event horizon, I was curious
• 7:39
  Speaker 4: if there is consensus in the scientific community about all
• 7:42
  Speaker 4: black holes being the same, or if they could vary
• 7:45
  Speaker 4: inside based on their density. For example, could a smaller
• 7:49
  Speaker 4: black hole be not a black hole at all, but
• 7:52
  Speaker 4: a dark star, while the super massive black holes at
• 7:55
  Speaker 4: the center of some galaxies be a more traditional black
• 7:58
  Speaker 4: hole or a string theory fuzz. Thank you very much
• 8:01
  Speaker 4: for the wonderful show and I look forward to hearing
• 8:03
  Speaker 4: your response.
• 8:04
  Speaker 1: All right, I feel like this question ken has an
• 8:08
  Speaker 1: identity problem in itself.
• 8:10
  Speaker 2: It's so many questions but also one.
• 8:12
  Speaker 1: But I think Matthew's basic question is about the identity
• 8:16
  Speaker 1: of black holes, Like, are all black holes the same?
• 8:19
  Speaker 1: Are they actually black holes? Could they be something else?
• 8:22
  Speaker 1: Is it a case of mistaken identity? Or do all
• 8:25
  Speaker 1: black holes come with an ID tag?
• 8:27
  Speaker 2: Yeah, he's basically wondering what's going on inside black holes
• 8:30
  Speaker 2: and if they all have to be the same on
• 8:32
  Speaker 2: the inside, and whether the things we've seen out there
• 8:35
  Speaker 2: in the universe that look like black holes could actually
• 8:38
  Speaker 2: be a bunch of different kinds of stuff that all
• 8:41
  Speaker 2: mimic black holes. So it's a really cool question guess
• 8:43
  Speaker 2: at the heart of what we think is going on
• 8:45
  Speaker 2: inside black holes.
• 8:46
  Speaker 1: M Like, maybe what we call black holes are actually
• 8:50
  Speaker 1: maybe a varity of different things.
• 8:53
  Speaker 2: Yeah, it's possible. And two black holes with the same mass,
• 8:56
  Speaker 2: do they have to look the same on the inside?
• 8:59
  Speaker 1: Wait on how much mass is in it? Or Like,
• 9:02
  Speaker 1: two things that look like black holes, are they actually
• 9:04
  Speaker 1: black holes? Or do you think he's asking if they're
• 9:06
  Speaker 1: the same, if there's any property that sets them apart?
• 9:09
  Speaker 2: Yeah, I think he's asking both of those questions, and
• 9:12
  Speaker 2: I think we should start with that. Like, if you
• 9:13
  Speaker 2: have two black holes that have the same mass, are
• 9:17
  Speaker 2: they the same thing? Are they indistinguishable? Or are they different?
• 9:21
  Speaker 2: And this is a big question in general, relativity goes
• 9:24
  Speaker 2: by the name of two black holes have hair? Essentially,
• 9:28
  Speaker 2: are there texture or details? Are there tiny little properties
• 9:31
  Speaker 2: that set two black holes apart the way two Like
• 9:34
  Speaker 2: identical twins are always a little bit different. Are two
• 9:38
  Speaker 2: black holes with the same mass, could they actually be
• 9:40
  Speaker 2: a little bit different on the inside.
• 9:43
  Speaker 1: Well, I feel there's two questions. One is like are
• 9:46
  Speaker 1: they the same? And can you tell if they're the same?
• 9:49
  Speaker 1: Aren't those two separate questions?
• 9:50
  Speaker 2: Yeah, those are two separate questions. So as you can see,
• 9:53
  Speaker 2: with black holes, we have like a constantly multiplying stream
• 9:56
  Speaker 2: of questions.
• 9:58
  Speaker 1: It's like a black hole of questions. It's a bit
• 10:01
  Speaker 1: of a rabbit hole. It's a black rabbit hole. So
• 10:04
  Speaker 1: which which question are we tackling? Can you tell if
• 10:06
  Speaker 1: two black holes are different or whether they're actually different inside?
• 10:10
  Speaker 2: Yeah, we can talk about all of it, but let's
• 10:11
  Speaker 2: start with what's going on inside black holes, at least
• 10:14
  Speaker 2: what we think is going on.
• 10:16
  Speaker 1: Okay, well, you sort of mentioned the no hair problem,
• 10:19
  Speaker 1: and that one's more of a like can you tell
• 10:21
  Speaker 1: if two black holes are different problem?
• 10:23
  Speaker 2: I think it also touches on whether the black holes
• 10:26
  Speaker 2: inherently are different. Are there features to two black holes
• 10:29
  Speaker 2: which tell them apart? Because in general relativity, the idea
• 10:33
  Speaker 2: is that all you can know about a black hole
• 10:36
  Speaker 2: are three different quantities how much mass it has, whether
• 10:40
  Speaker 2: it's spinning, and whether it has electrical charge. And to
• 10:44
  Speaker 2: say that that's all you can know about a black
• 10:45
  Speaker 2: hole means that that's what defines a black hole. So
• 10:49
  Speaker 2: in general relativity, two black holes with the same mass, spin,
• 10:52
  Speaker 2: and charge really are identical according to that theory.
• 10:57
  Speaker 1: From the outside right, I mean, it's basically saying that's
• 11:00
  Speaker 1: all you can tell about what's inside a black hole.
• 11:02
  Speaker 2: It means those are the only properties of the objects,
• 11:05
  Speaker 2: So even on the inside, they would be identical again
• 11:08
  Speaker 2: according to general relativity. Important caveat we can get to later.
• 11:12
  Speaker 1: But I guess, how can they be exactly identical or
• 11:15
  Speaker 1: how can we know or how can the theory know
• 11:16
  Speaker 1: that it's identical because inside the black hole maybe things
• 11:20
  Speaker 1: are arranged differently.
• 11:21
  Speaker 2: We can't know currently because we can't see inside black holes,
• 11:24
  Speaker 2: but that doesn't stop the theory from predicting what's there
• 11:27
  Speaker 2: and describing what we think is happening. And according to
• 11:31
  Speaker 2: general relativity, again big caveat there we can get to
• 11:34
  Speaker 2: in a minute. All these black holes, if they have
• 11:37
  Speaker 2: the same mass, spin, in charge, really are identical. They
• 11:40
  Speaker 2: have the same exact internal structure because they're defined just
• 11:44
  Speaker 2: by those three numbers, So there's no whiggle room. There's
• 11:47
  Speaker 2: no opportunity for a black hole made of bananas to
• 11:50
  Speaker 2: be different from a black hole made of bowling balls
• 11:52
  Speaker 2: or squirrels if they have the same mass, spin, and charge.
• 11:57
  Speaker 2: That's again according to general relativity, which is predict what's
• 12:00
  Speaker 2: inside black holes, though it's not something we've seen.
• 12:03
  Speaker 1: I guess what I mean is like a black hole
• 12:04
  Speaker 1: is like a sphere right like to us, it has volume,
• 12:08
  Speaker 1: and so what does general relativity predict is inside of
• 12:11
  Speaker 1: that sphere just a singularity? Like everything just collapses instantly
• 12:17
  Speaker 1: or what.
• 12:17
  Speaker 2: Well, a black hole that's had time to settle, everything
• 12:20
  Speaker 2: will fall towards the singularity. So if things are still
• 12:23
  Speaker 2: dynamically falling into a black hole, its state is changing.
• 12:27
  Speaker 2: But after a long time. When it settles, then it's
• 12:30
  Speaker 2: just defined by these three numbers. And yeah, two black
• 12:33
  Speaker 2: holes with the same mass will each have a singularity
• 12:36
  Speaker 2: inside them with the same.
• 12:37
  Speaker 1: Mass and nothing between the singularity and the event horizon.
• 12:42
  Speaker 1: What does general relativity say is between the singularity which
• 12:45
  Speaker 1: is at the center, and the event horizon, which is
• 12:47
  Speaker 1: the outer shell of the black hole.
• 12:49
  Speaker 2: So it depends a little bit on the mass, spin,
• 12:51
  Speaker 2: in charge. These kinds of black holes have different internal structures,
• 12:56
  Speaker 2: like the simplest kind one with just mass and no spin,
• 12:59
  Speaker 2: no charge, or this is the kind most people talk
• 13:01
  Speaker 2: about and think about, is just a sphere and in
• 13:04
  Speaker 2: the inside you have the singularity and there's nothing else.
• 13:07
  Speaker 2: If it's charged or if it's spinning, then the structure
• 13:10
  Speaker 2: in the inside is a little bit different, Like you
• 13:12
  Speaker 2: don't actually have a singularity if it's spinning, you have
• 13:15
  Speaker 2: a ringularity because you need an object that can spin
• 13:18
  Speaker 2: and singularities can't. And you can have different kinds of
• 13:21
  Speaker 2: horizons inside the black hole or even near the black
• 13:25
  Speaker 2: hole on the outside if it's spinning and if it
• 13:27
  Speaker 2: has charge.
• 13:29
  Speaker 1: Well, that's an interesting concept you just mentioned, which is
• 13:31
  Speaker 1: like the settling of a black hole. Now does that
• 13:35
  Speaker 1: happen like instantly over billions of years trillions? Does it
• 13:38
  Speaker 1: ever happen? Doesn't times stop? Inside of a black hole?
• 13:42
  Speaker 2: Nothing happens instantly, right. Relativity describes how there's a maximum
• 13:46
  Speaker 2: speed limit to the universe, and so you definitely can't
• 13:49
  Speaker 2: have things instantly collapsing into a singularity. It always takes time.
• 13:53
  Speaker 2: How much time it takes depends on who you are
• 13:56
  Speaker 2: and where you are. Like, if you're outside the black
• 13:59
  Speaker 2: hole and you're watching things fall in, you'll actually not
• 14:01
  Speaker 2: see them fall in because time slows down so much
• 14:04
  Speaker 2: at the event horizon. You'll see them frozen at the
• 14:07
  Speaker 2: event horizon. If you are riding that banana into the
• 14:10
  Speaker 2: black hole, then you will see yourself past the event
• 14:13
  Speaker 2: horizon and you'll fall in, and you'll reach the singularity
• 14:16
  Speaker 2: in a finite amount of time. So how long it
• 14:19
  Speaker 2: takes depends on the observer. In general relativity, these things
• 14:21
  Speaker 2: are very screwy.
• 14:23
  Speaker 1: But I guess maybe then the scenario I wonder that
• 14:26
  Speaker 1: Matthew's thinking about me, Like, if I have two black holes,
• 14:29
  Speaker 1: they have the same mass and energy and spin in
• 14:31
  Speaker 1: charge and all that they're identical, But then black hole
• 14:35
  Speaker 1: A eats a banana, and black hole b eats a
• 14:37
  Speaker 1: bowling ball. Like to us, it takes some time for
• 14:42
  Speaker 1: the banana to and bolling bull to make it to
• 14:44
  Speaker 1: the center of the black hole. So are those two
• 14:47
  Speaker 1: black holes different in the meantime.
• 14:49
  Speaker 2: In the meantime they are. Yeah, But if the bowling
• 14:52
  Speaker 2: ball and the banana have the same mass, and like
• 14:55
  Speaker 2: that's a tiny bowling ball or a huge banana, then
• 14:57
  Speaker 2: eventually they do reach steady state, which is just described
• 15:01
  Speaker 2: by the mass, spin and charge.
• 15:04
  Speaker 1: But could we tell that one aid the banana and
• 15:07
  Speaker 1: the other one ate the bowling ball.
• 15:08
  Speaker 2: We couldn't, right, Not after they've settled into the singularity exactly.
• 15:11
  Speaker 2: According to general relativity, that information is lost. Before that
• 15:15
  Speaker 2: information is still within the event horizon. We can't see it,
• 15:19
  Speaker 2: but it does still exist within the black hole after
• 15:22
  Speaker 2: it's settled into the singularity. According to general relativity, that
• 15:25
  Speaker 2: information is gone because the state is perfectly described by
• 15:29
  Speaker 2: the mass, spin in charge.
• 15:31
  Speaker 4: Mmm.
• 15:32
  Speaker 1: So then it's sort of possible for two black holes
• 15:34
  Speaker 1: to be different, perhaps, but for us to not be
• 15:36
  Speaker 1: able to tell them apart.
• 15:38
  Speaker 2: Yeah, that is possible, and that's a transient state.
• 15:42
  Speaker 1: Right, Well, black holes are eating all the time, right,
• 15:44
  Speaker 1: So black.
• 15:44
  Speaker 2: Holes in the real world yet are always eating are
• 15:47
  Speaker 2: They're always surrounded by something. There's never a true vacuum.
• 15:50
  Speaker 2: There's always a solar wind or particles everywhere. So yeah, absolutely,
• 15:53
  Speaker 2: black holes are always eating in real life. In the
• 15:56
  Speaker 2: sort of thought experiments we construct, you could imagine a
• 15:59
  Speaker 2: black hole surrounded by actually nothing and then you just
• 16:02
  Speaker 2: drop a banana into it. But yeah, and the real universe,
• 16:05
  Speaker 2: black holes are never surrounded by nothing.
• 16:08
  Speaker 1: But I think, as you were saying, this all depends
• 16:10
  Speaker 1: on general relativity.
• 16:12
  Speaker 2: Yeah, exactly. This is a picture from classical physics that
• 16:16
  Speaker 2: says that singularities can exist within black holes, and that
• 16:19
  Speaker 2: it matter could be compressed into a tiny dot. That's
• 16:22
  Speaker 2: totally incompatible with what we know about the nature of
• 16:24
  Speaker 2: reality that is quantum mechanical. Though, when things get really
• 16:27
  Speaker 2: really small, like the size of singularities, different rules take
• 16:31
  Speaker 2: over and have to be accounted for, rules that general
• 16:34
  Speaker 2: relativity ignores. So we don't think singularities actually do exist
• 16:38
  Speaker 2: at the heart of any black holes in our universe.
• 16:41
  Speaker 2: We think, if black holes are even real, that there's
• 16:44
  Speaker 2: some other kind of thing going on, something dictated by
• 16:46
  Speaker 2: a different theory of physics, not general relativity, one that
• 16:49
  Speaker 2: correctly incorporates the quantum nature of our universe, a theory
• 16:53
  Speaker 2: we don't have today, so we can't say what we
• 16:56
  Speaker 2: actually think is inside a black hole.
• 17:00
  Speaker 1: I think maybe Matthew's question is, like, let's say black
• 17:02
  Speaker 1: holes they're all a little bit different inside, depending on
• 17:05
  Speaker 1: their density, Like maybe some of them are super dense
• 17:09
  Speaker 1: but collass into a singularity, or maybe some do, or
• 17:12
  Speaker 1: maybe some are more like uh, let strings every fuzzballs.
• 17:16
  Speaker 1: I wonder if they can be different in that way inside,
• 17:18
  Speaker 1: but to us from the outside they all look the same.
• 17:21
  Speaker 2: It's possible, and it depends on your flavor of quantum gravity.
• 17:25
  Speaker 2: If what he's describing is true. There are no classical
• 17:28
  Speaker 2: black holes in the universe. They're all some weird quantum version.
• 17:31
  Speaker 2: And you're right, there could be a variety, right, There
• 17:33
  Speaker 2: could be some fuzzballs and some dark stars and some
• 17:36
  Speaker 2: white holes and some other kind of crazy stuff going on.
• 17:40
  Speaker 2: And whether we could see the difference on the outside
• 17:42
  Speaker 2: also depends on the details of the quantum gravity theory.
• 17:46
  Speaker 2: In some scenarios, you can tell what's inside a black
• 17:48
  Speaker 2: hole by studying the patterns of the hawking radiation, which
• 17:52
  Speaker 2: might be quantum entangled with the details of what's going
• 17:55
  Speaker 2: on inside and leaking that information out. There are other
• 17:58
  Speaker 2: quantum theories of black holes in which you still can't
• 18:01
  Speaker 2: get that information out even though it is inside the
• 18:04
  Speaker 2: event horizon. So it depends on your flavor of quantum
• 18:08
  Speaker 2: black hole. But it's possible that all these things do
• 18:10
  Speaker 2: really exist in our universe.
• 18:12
  Speaker 1: Hmmm. It sounds like it sort of depends on what
• 18:14
  Speaker 1: you define as a black hole, right, Like, if you
• 18:16
  Speaker 1: define it as what a general what relativity calls a
• 18:20
  Speaker 1: black hole, then you get one as er. But if
• 18:22
  Speaker 1: you just define it as something that has an event
• 18:24
  Speaker 1: horizon that doesn't let you look inside, it is possible
• 18:28
  Speaker 1: maybe to have different kinds of black holes exactly.
• 18:31
  Speaker 2: And remember, not all of these objects even have event horizons.
• 18:35
  Speaker 2: When we talk about a black hole, we sort of
• 18:37
  Speaker 2: imply an event horizon. But it's possible that some of
• 18:40
  Speaker 2: the things out there in the universe that we call
• 18:42
  Speaker 2: black holes don't actually have event horizons. We haven't verified
• 18:45
  Speaker 2: the event horizon nature of those objects. They're just really
• 18:49
  Speaker 2: really small, really really massive, and really really space bendy
• 18:53
  Speaker 2: in the way we expect black holes to be, but
• 18:56
  Speaker 2: we haven't like zoomed up close and proven that they
• 18:58
  Speaker 2: actually have event horizons. And some of these theories don't
• 19:01
  Speaker 2: create objects with event horizons.
• 19:03
  Speaker 1: But some do, right, Like you could have a dark
• 19:05
  Speaker 1: star that does have event horizon.
• 19:07
  Speaker 2: Perhaps, yeah, some of them do. It depends on the
• 19:11
  Speaker 2: flavor or quantum gravity.
• 19:12
  Speaker 1: Hmm, all right, well then so then the answer for
• 19:16
  Speaker 1: Matthew is, uh, it depends and we don't.
• 19:19
  Speaker 2: Know that summarizes most of physics.
• 19:23
  Speaker 1: Yes, it depends that black hole that's in your backyard.
• 19:27
  Speaker 2: What it means is that there's still so much to
• 19:29
  Speaker 2: learn about the nature of these objects. And the answer
• 19:31
  Speaker 2: to the question might not be it's this kind or
• 19:33
  Speaker 2: it's that kind, but it's all the kinds. I love
• 19:36
  Speaker 2: that possibility.
• 19:37
  Speaker 1: Mmm. So it sort of maybe depends on what's actually
• 19:40
  Speaker 1: going on, which we don't have a clear theory about.
• 19:43
  Speaker 2: And we might not ever know.
• 19:45
  Speaker 1: Ever.
• 19:46
  Speaker 2: It might be that the universe prevents us from ever
• 19:48
  Speaker 2: seeing inside these black holes, or that the information in
• 19:51
  Speaker 2: the Hawking radiation doesn't reveal what's inside them. It might
• 19:55
  Speaker 2: be that we're not smart enough to figure out the universe.
• 19:57
  Speaker 1: Who knows, Boy, I wish you had left the question
• 20:00
  Speaker 1: on a more positive note, But it could.
• 20:03
  Speaker 2: Be that we figure it all out and then you
• 20:05
  Speaker 2: go in ten generations the latest. Daniel and Jorge are
• 20:08
  Speaker 2: explaining it all to you on their podcast.
• 20:11
  Speaker 1: All right, all right, yeah, that's good. That doesn't leave
• 20:14
  Speaker 1: us in a black hole. All right, let's tackle some
• 20:17
  Speaker 1: of our other questions. We have questions here about the
• 20:20
  Speaker 1: number of neutrinas in the universe and also about what
• 20:23
  Speaker 1: it's like to bob up and down on a gravitation wave.
• 20:27
  Speaker 1: So let's stick into those. But first let's take a
• 20:29
  Speaker 1: quick break. Right we're answering questions from listeners, and our
• 20:46
  Speaker 1: next question comes from Sam from British Columbia.
• 20:50
  Speaker 3: Hello, Daniel and Jorge, this is Sam from British Columbia
• 20:53
  Speaker 3: and thank you for your podcasts and availability to answer
• 20:56
  Speaker 3: our questions. It is really appreciated about neutrinos. You always
• 21:01
  Speaker 3: mention how many trillions are passing through the Earth every second.
• 21:05
  Speaker 3: This got me wondering about how many neutrinos are estimated
• 21:08
  Speaker 3: to exist in the universe, as well as proportions for
• 21:11
  Speaker 3: the other main particle groups.
• 21:13
  Speaker 2: In the standard model.
• 21:14
  Speaker 3: It has often estimated that there are ten to the
• 21:16
  Speaker 3: eighty particles in the universe. When he asked chat gpt
• 21:20
  Speaker 3: for help, I got back that each of the groups
• 21:23
  Speaker 3: of leptons, quarks, and bow sounds each were in the
• 21:26
  Speaker 3: order of ten to the eighty, and then that there
• 21:28
  Speaker 3: were significantly more electrons than neutrinos, and also that there
• 21:32
  Speaker 3: were about ten to the eighty of each. I think
• 21:35
  Speaker 3: chat gpt once again was confused, and I'm hoping you
• 21:38
  Speaker 3: can help unconfuse me.
• 21:40
  Speaker 1: Thanks all right, Well, I'm glad that we were his
• 21:43
  Speaker 1: second choice for answering questions about the universe.
• 21:48
  Speaker 2: Oh man, chat GPT.
• 21:51
  Speaker 1: I guess chat gpt is free. I guess you don't
• 21:55
  Speaker 1: have to listen to ads d I.
• 21:57
  Speaker 2: Think you have to pay for some version of chat GPT.
• 22:00
  Speaker 2: No version of it can be relied on to answer
• 22:02
  Speaker 2: physics questions. I see, well, you know what they say,
• 22:06
  Speaker 2: you get what you pay for. You can do get
• 22:08
  Speaker 2: what you paid for.
• 22:09
  Speaker 1: It sounds like chat jipt did not answer Sam's question
• 22:12
  Speaker 1: or game of an answer that maybe it was confusing.
• 22:15
  Speaker 2: Well, it's also not designed to answer physics questions. It's
• 22:19
  Speaker 2: designed to generate text which looks like the answers to
• 22:22
  Speaker 2: questions it's not designed to do any reasoning, or have
• 22:24
  Speaker 2: a model of the universe, or actually think in any way,
• 22:28
  Speaker 2: or be accurate or explain things. So I wouldn't rely
• 22:31
  Speaker 2: on chat gpt to answer any questions. Yet you could
• 22:35
  Speaker 2: say that about anything. Man, your toaster hasn't replaced you yet.
• 22:39
  Speaker 1: Well, you know, it's like they say, chat chipet is
• 22:42
  Speaker 1: not designed to do basic math, right, Like, if you
• 22:44
  Speaker 1: ask it a math question, it may not give you
• 22:46
  Speaker 1: the right answer. But I've seen examples of like asking
• 22:48
  Speaker 1: Chad Gipt to check using some sort of math toolbox,
• 22:52
  Speaker 1: and then it gives you the right answer.
• 22:53
  Speaker 2: Yeah, you know a stop clock is right a few
• 22:55
  Speaker 2: times a day, right, yeah?
• 22:57
  Speaker 1: Yeah, So you could ask chat gipt twice a day
• 23:00
  Speaker 1: to go read every physics paper in the universe and
• 23:03
  Speaker 1: then come back to you with an answer, which is
• 23:05
  Speaker 1: basically what we do in this podcast.
• 23:07
  Speaker 2: And it's the wrong tool for the job. You know.
• 23:09
  Speaker 2: Its job is to generate text which resembles answers, not
• 23:13
  Speaker 2: to reason and think and provide explanations. I don't think
• 23:17
  Speaker 2: it'll ever be a good place to ask physics questions.
• 23:19
  Speaker 2: I say, I see somedays somebody might actually develop an
• 23:22
  Speaker 2: AI which is good at the reasoning and thinking and explaining.
• 23:25
  Speaker 2: I'm not ruling that out. I'm pretty sure that will
• 23:27
  Speaker 2: happen one day, but large language models won't get there.
• 23:32
  Speaker 1: I think what you're saying is that we're the right tools.
• 23:34
  Speaker 2: Yes, ask us where we were, just the pair tools,
• 23:41
  Speaker 2: just like data on Star Trek.
• 23:42
  Speaker 1: Right, there you go, There you go. Maybe the next
• 23:45
  Speaker 1: chat GBT should be called Daniel and Cordy Chat DJ.
• 23:49
  Speaker 1: All right, well, let's get to Sam's question here. Samon
• 23:51
  Speaker 1: wants to know how many neutrinias there are in the universe, right, Like,
• 23:56
  Speaker 1: what's a good estimate for the number of neutrinos in
• 23:58
  Speaker 1: the universe?
• 23:59
  Speaker 2: Such an awesome question because there are so many neutrinos
• 24:03
  Speaker 2: in the universe, it's mind boggling.
• 24:06
  Speaker 1: Well, there's a lot of everything in the universe, right, Well,
• 24:08
  Speaker 1: there's only one me and one you. How do you know.
• 24:12
  Speaker 2: Ship a theseus man, if there's another copy of me,
• 24:15
  Speaker 2: it's not me.
• 24:18
  Speaker 1: Well, there could be one you that has gone through
• 24:21
  Speaker 1: the same experiences as you. Wouldn't that be the same Anyways,
• 24:24
  Speaker 1: let's get back on track here. It's a big universe.
• 24:28
  Speaker 1: Asne wants to know how many neutrinios are Why do
• 24:30
  Speaker 1: you think he wants to know how many there are? Like,
• 24:32
  Speaker 1: why neutrinos? Why not how many electrons or quarks there
• 24:36
  Speaker 1: are in the universe?
• 24:37
  Speaker 2: I think because neutrinos give us a window into a
• 24:40
  Speaker 2: deeper understanding of what's out there in the universe. Like
• 24:43
  Speaker 2: we're made out of quarks and electrons, and that feels like, Oh,
• 24:46
  Speaker 2: that's the universe, what's all that made out of? But
• 24:49
  Speaker 2: as soon as you realize that our senses are limited
• 24:52
  Speaker 2: and that there's so much more going on in the
• 24:54
  Speaker 2: universe than the little bits of matter that you and
• 24:57
  Speaker 2: I are made out of, it makes you wonder what's
• 24:59
  Speaker 2: out there, how much of it is there? And new
• 25:01
  Speaker 2: trinos are like the tip of that invisible matter Iceberg.
• 25:05
  Speaker 1: I see, Well, how would you answer the question of
• 25:08
  Speaker 1: how many new trinos there are?
• 25:10
  Speaker 2: Yeah, so it takes a few steps. Basically, you have
• 25:12
  Speaker 2: to know how many protons there are in the universe,
• 25:15
  Speaker 2: and then you have to try to figure out how
• 25:16
  Speaker 2: many neutrinos there are per proton. And it turns out
• 25:20
  Speaker 2: that we can do both of those calculations.
• 25:21
  Speaker 1: Wait, why do we have to go through protons?
• 25:24
  Speaker 2: Because the way we figure out how many new trinos
• 25:26
  Speaker 2: there are in the universe is by going back to
• 25:28
  Speaker 2: the very very early universe and understanding how photons and
• 25:32
  Speaker 2: protons and neutrinos and dark matter all slashed around and
• 25:36
  Speaker 2: pushed against each other. It's this plasma soup at the
• 25:39
  Speaker 2: very beginning of the universe that reveals the answers to
• 25:41
  Speaker 2: all of these questions. From measurements of the cosmic microwave background,
• 25:45
  Speaker 2: we can learn a lot about that plasma and how
• 25:48
  Speaker 2: it was slashing, and it tells us the answers to
• 25:50
  Speaker 2: all of these things. Then, specific ways it tells us
• 25:53
  Speaker 2: some ratios allow us to get to these answers.
• 25:56
  Speaker 1: Like the beginning of the universe tells you the original
• 25:59
  Speaker 1: recipe of the universe kind.
• 26:00
  Speaker 2: Of yeah, exactly, And some of that hasn't changed, and
• 26:03
  Speaker 2: some of that has changed, and we know how that
• 26:05
  Speaker 2: has changed, and we can evolve that through time. But
• 26:07
  Speaker 2: it basically starts the machine and tells us how things
• 26:11
  Speaker 2: evolve through time.
• 26:12
  Speaker 1: But is it even possible to get this answer because
• 26:14
  Speaker 1: aren't neutrino's being created, for example, all the time in
• 26:17
  Speaker 1: the sun? Like, are new neutrinos being made all the time?
• 26:21
  Speaker 2: Yeah? The specific number like to the individual neutrino is
• 26:25
  Speaker 2: not very well defined because neutrinos are quantum particles, and
• 26:29
  Speaker 2: so they even have probabilities of existing. Like you have
• 26:32
  Speaker 2: a certain reaction that might generate neutrinos. Whether it actually
• 26:36
  Speaker 2: did or not isn't even determined until it interacts with
• 26:38
  Speaker 2: some classical objects. So from a quantum mechanical point of view,
• 26:42
  Speaker 2: getting the answer down to like the individual neutrino is
• 26:45
  Speaker 2: not technically possible, and even zooming out a little bit
• 26:48
  Speaker 2: as you say, there are neutrino factories in the universe
• 26:50
  Speaker 2: and neutrinos being annihilated. Neutrinos can be created and destroyed,
• 26:55
  Speaker 2: so the number is changing. But it turns out that
• 26:57
  Speaker 2: the number of neutrinos being created in roid in the
• 27:00
  Speaker 2: universe is really tiny compared to like the huge reservoir
• 27:04
  Speaker 2: of neutrinos we already have.
• 27:06
  Speaker 1: Well, how do you.
• 27:07
  Speaker 2: Know, because we think we understand those processes, and we've
• 27:09
  Speaker 2: measured neutrinos that come from space and neutrinos that pass
• 27:12
  Speaker 2: through the Earth. Neutrino physics is something we're really starting
• 27:15
  Speaker 2: to get a grip on in like the last twenty years.
• 27:18
  Speaker 2: So we are a pretty good handle on how many
• 27:21
  Speaker 2: neutrinos are out there and how many are being made
• 27:23
  Speaker 2: by the Sun. We even see neutrinos generated by crazy
• 27:26
  Speaker 2: sources in other galaxies. Neutrino astronomy is something that's really
• 27:31
  Speaker 2: come into its own in the last couple of decades.
• 27:34
  Speaker 1: And so what's the picture. It's like the Sun is
• 27:36
  Speaker 1: making bazillions of neutrinos, but that's very like a drip
• 27:40
  Speaker 1: of water compared to like we're swimming in an ocean
• 27:42
  Speaker 1: of neutrinos.
• 27:43
  Speaker 2: Zechon what you're saying exactly. It's like asking what's the
• 27:45
  Speaker 2: volume of the Pacific? Well, you don't really have to
• 27:47
  Speaker 2: worry about evaporation and rain because those are tiny details
• 27:51
  Speaker 2: relative to massive volume of water there.
• 27:54
  Speaker 1: And so then what's the connection to protons? Why do
• 27:57
  Speaker 1: we need to know how many protons there are?
• 28:00
  Speaker 2: Know how many neutrinos there are per proton. That's a
• 28:03
  Speaker 2: measurement we can make back in the very early universe.
• 28:06
  Speaker 2: If you wind the universe backwards, we see that it
• 28:08
  Speaker 2: gets hotter and denser. Right now, the universe is kind
• 28:11
  Speaker 2: of old and cold, very dilute, very chill. But as
• 28:15
  Speaker 2: you wind time backwards and you undo the expansion, things
• 28:18
  Speaker 2: get very hot and very dense. Back to some early
• 28:21
  Speaker 2: state where there were protons and there were photons, and
• 28:24
  Speaker 2: there were electrons, and there were also neutrinos zipping about,
• 28:27
  Speaker 2: and we can see photons from that moment. This is
• 28:30
  Speaker 2: the moment we call the surface of last scattering, when
• 28:33
  Speaker 2: the universe became transparent to those photons, so they're still around.
• 28:37
  Speaker 2: So we can see a picture of what that early
• 28:39
  Speaker 2: universe plasma looked like. It's called the cosmic microwave background radiation,
• 28:43
  Speaker 2: and we can see patterns in it. We see wiggles
• 28:46
  Speaker 2: and we see waves. Those wiggles and waves are determined
• 28:49
  Speaker 2: by how it's slashing, which depends on how many protons
• 28:52
  Speaker 2: there are, how many photons there are, how much dark
• 28:55
  Speaker 2: matter there is. As you change those fractions, that early
• 28:58
  Speaker 2: universe plasma slashed differently because those different pieces all behave differently.
• 29:03
  Speaker 1: But even neutrinos were consequential at the beginning of the
• 29:06
  Speaker 1: universe because I thought neutrinos were basically massless and they're
• 29:10
  Speaker 1: ghostly and they they don't really interact with anything much.
• 29:14
  Speaker 1: Isn't there like a wide range of neutrino proportions that
• 29:18
  Speaker 1: could have been there at the beginning of the universe.
• 29:20
  Speaker 2: Yeah. Absolutely. Neutrinos don't interact very much, but they do
• 29:23
  Speaker 2: have energy, and so they affect the energy density of
• 29:26
  Speaker 2: the universe, which changes its expansion. And because neutrinos are
• 29:30
  Speaker 2: very very light, they sort of fall into the same
• 29:32
  Speaker 2: category as photons. Back in the early universe, everything that
• 29:36
  Speaker 2: was moving almost at the speed of light or at
• 29:38
  Speaker 2: the speed of light gets counted kind of as radiation.
• 29:42
  Speaker 2: Remember we talked about this once, and stuff that's moving
• 29:45
  Speaker 2: very very slowly gets counted as matter. And so things
• 29:48
  Speaker 2: that are moving as radiation do affect the expansion of
• 29:51
  Speaker 2: the universe because they affect the energy density in this
• 29:54
  Speaker 2: complicated way. So you're right, the neutrinos are weak, but
• 29:57
  Speaker 2: they still have energy and that affects the old overall
• 30:00
  Speaker 2: balancing of these equations in general relativity.
• 30:03
  Speaker 1: There's stills a piece of the pot.
• 30:05
  Speaker 2: Yeah, exactly. And it turns out there's a huge number
• 30:08
  Speaker 2: of them, so they have a pretty big influence.
• 30:10
  Speaker 1: Oh, how big of a number, Like if you had
• 30:12
  Speaker 1: a pie chart of the universe at the beginning in
• 30:14
  Speaker 1: the Big Bang, how big is the neutrino slice.
• 30:17
  Speaker 2: Yeah, so you wouldn't even be able to see the
• 30:19
  Speaker 2: protons on that pie chart because there are approximately one
• 30:22
  Speaker 2: billion neutrinos for every proton.
• 30:25
  Speaker 1: Well in terms of quantity, but in energy, how big
• 30:28
  Speaker 1: of a slice is it there?
• 30:30
  Speaker 2: The numbers are much more closely balanced. There are many
• 30:32
  Speaker 2: fewer protons, but protons have a huge mass compared to
• 30:36
  Speaker 2: neutrinos that have almost no mass. On the other hand,
• 30:39
  Speaker 2: the neutrinos have a lot more kinetic energy. Right they're
• 30:42
  Speaker 2: moving really really fast, They're almost at the speed of light,
• 30:45
  Speaker 2: so the energy is there are much better balanced that
• 30:47
  Speaker 2: are in the same order of magnitude. The numbers aren't
• 30:50
  Speaker 2: exactly determined, but the original question was about the number
• 30:53
  Speaker 2: of neutrinos in the universe, and so there we need
• 30:55
  Speaker 2: the number ratio, and the cosmic microwave background radiation tells
• 31:00
  Speaker 2: us that there are like three hundred and thirty million
• 31:03
  Speaker 2: neutrinos per cubic meter of space back then, and there
• 31:07
  Speaker 2: was less than one proton per cubic meter, so the
• 31:10
  Speaker 2: ratio is about a billion I.
• 31:12
  Speaker 1: See, so neutrino's were a pretty significant slice of the universe,
• 31:15
  Speaker 1: but in terms of quantity, like number of neutrinos because
• 31:17
  Speaker 1: they're so small at night that the number of them
• 31:20
  Speaker 1: dwarfs the number of protons around us exactly.
• 31:23
  Speaker 2: So there's this incredible ocean of neutrinos back in the
• 31:26
  Speaker 2: early universe and still today. Like the density of neutrinos
• 31:30
  Speaker 2: has dropped because the universe expands and everything gets more
• 31:34
  Speaker 2: dilute except for dark energy, but most of those neutrinos
• 31:37
  Speaker 2: are still around. It's called the cosmic neutrino background, and
• 31:41
  Speaker 2: it's something we're searching for in neutrino experiments.
• 31:44
  Speaker 1: Does it depend still on the number of protons? Is
• 31:47
  Speaker 1: it the same ratio like three hundred and thirty million
• 31:50
  Speaker 1: to one or billion to.
• 31:51
  Speaker 2: One, depends a little bit what you count as a proton.
• 31:54
  Speaker 2: Like some of those protons go on to make helium.
• 31:57
  Speaker 2: There's still protons in there, but like now we call
• 31:59
  Speaker 2: them helium instead of protons or hydrogen. But most of
• 32:02
  Speaker 2: those protons are still around, and most of those neutrinos
• 32:04
  Speaker 2: are still around, and because they're both matter, they both
• 32:07
  Speaker 2: get diluted in the same way as the universe expands,
• 32:10
  Speaker 2: and so their ratio is approximately the same.
• 32:14
  Speaker 1: Then to get account of the number and neutrinos, we
• 32:16
  Speaker 1: need a count of the number of protons, So how
• 32:18
  Speaker 1: many protons are there in the universe.
• 32:20
  Speaker 2: So in the observable universe, we don't know what's in
• 32:22
  Speaker 2: the full universe right past where we can see. We
• 32:25
  Speaker 2: know the density of protons, which is about a fifth
• 32:27
  Speaker 2: per cubic meter, and we know roughly the volume of
• 32:31
  Speaker 2: the observable universe, which is like ten to the eighty
• 32:36
  Speaker 2: cubic meters or so, and that means around ten to
• 32:39
  Speaker 2: the seventy nine protons in the observable universe. That's ten
• 32:44
  Speaker 2: with seventy nine zeros. It's not even like a name
• 32:47
  Speaker 2: for that.
• 32:47
  Speaker 1: Number, Sure there is, we can make one.
• 32:49
  Speaker 2: Up, right, there will be soon.
• 32:52
  Speaker 1: What's the number bananion?
• 32:56
  Speaker 2: Coincidentally, there's exactly one bananion of protons in the universe.
• 33:00
  Speaker 1: Oh my gosh, such a coincidence.
• 33:03
  Speaker 2: Which means that there's a billion bananians of neutrinos in
• 33:08
  Speaker 2: the universe, because it's about a billion neutrinos per.
• 33:10
  Speaker 1: Proton, So ten to the what eighty eight.
• 33:13
  Speaker 2: About ten to the eighty eight neutrinos in the observable universe.
• 33:17
  Speaker 1: Observable universe, but the observable universe is getting bigger every day. Right,
• 33:22
  Speaker 1: So that number is going up.
• 33:23
  Speaker 2: Actually depends a little bit how you think about distance.
• 33:26
  Speaker 2: The universe is expanding faster than the speed of light,
• 33:29
  Speaker 2: so the fraction of stuff in the universe we can
• 33:31
  Speaker 2: see is actually shrinking, right, And eventually a lot of
• 33:34
  Speaker 2: stuff is going to fall outside of our horizon. So
• 33:37
  Speaker 2: the number of particles in the observable universe is actually decreasing.
• 33:40
  Speaker 1: WHOA, the universe is its outgrowing how far we can see.
• 33:45
  Speaker 2: Yeah, exactly. The universe is expanding faster than our horizon is,
• 33:49
  Speaker 2: so particles are disappearing from the observable universe. That's another
• 33:53
  Speaker 2: reason why the number is not fixed.
• 33:55
  Speaker 1: Well, it may not even be fixed, right, Like, maybe
• 33:58
  Speaker 1: the universe is infinite, in which case there's maybe an
• 34:01
  Speaker 1: infinite number of neutrinos.
• 34:02
  Speaker 2: Yeah, exactly. In that case, you could still measure the
• 34:04
  Speaker 2: density of neutrinos like three hundred and thirty million per
• 34:07
  Speaker 2: cubic meter, but the total number in the whole universe
• 34:10
  Speaker 2: would be infinite. If the universe is infinite, and if
• 34:13
  Speaker 2: the universe beyond a horizon is similar to the bits
• 34:17
  Speaker 2: that we see here, could be that what's beyond the
• 34:19
  Speaker 2: horizon is very different, right, And then we live in
• 34:21
  Speaker 2: a weird patch of the universe.
• 34:23
  Speaker 1: Right right, It depends and we don't know, is what
• 34:25
  Speaker 1: you're saying. But what do you think is the ratio
• 34:30
  Speaker 1: of like in the universe, the ratio between neutrinos and Daniels.
• 34:36
  Speaker 1: Is it infinite to one or is there a fixed number?
• 34:41
  Speaker 2: That's the question philosopher has been wondering about for thousands
• 34:44
  Speaker 2: of years, and we're not going to answer it today
• 34:45
  Speaker 2: on the podcast.
• 34:48
  Speaker 1: That's right. We don't have the time. That's why we're
• 34:50
  Speaker 1: not answering.
• 34:50
  Speaker 2: That's right, exactly. No, I think if there are other
• 34:53
  Speaker 2: Daniels out there, there's still not me because I'm not
• 34:56
  Speaker 2: experiencing them, even if they think that there Daniel. I'm
• 34:59
  Speaker 2: experien think this one, which makes this one different, which
• 35:02
  Speaker 2: makes me unique. I'm only experiencing one Daniel.
• 35:05
  Speaker 1: Unless they're having the exact same experience you are, in
• 35:08
  Speaker 1: which case, in which case, there the outside can't tell
• 35:11
  Speaker 1: the difference.
• 35:13
  Speaker 2: But we can from inside, right inside the Daniel horizon,
• 35:16
  Speaker 2: you can tell which Daniel you are.
• 35:19
  Speaker 1: But your feeling of uniqueness is the same feeling of
• 35:22
  Speaker 1: unique is the other Daniel's having.
• 35:23
  Speaker 2: Yeah, that's right, But I'm only feeling my feeling of uniqueness.
• 35:26
  Speaker 2: I'm not feeling bears. Oh, I see.
• 35:28
  Speaker 1: So to you, there's only one Daniel, yeah, but maybe
• 35:30
  Speaker 1: to someone outside of the universe there is an infinite
• 35:33
  Speaker 1: number of Daniels.
• 35:34
  Speaker 2: Yeah. And it means and we don't know, And to
• 35:36
  Speaker 2: me is all that matters, because I'm the only consciousness
• 35:38
  Speaker 2: I'm actually aware of in the universe.
• 35:41
  Speaker 1: But I'm not asking what matters to you. I'm wondering
• 35:45
  Speaker 1: what matters to me, Daniel.
• 35:50
  Speaker 2: I don't know if you're even real.
• 35:51
  Speaker 1: So that's right, We're all in them some AI's imagination.
• 35:56
  Speaker 1: All right, Well, I think that answers the question for Sam.
• 35:59
  Speaker 1: The estimate of the number of neutrinos in the observable
• 36:01
  Speaker 1: universe is ten to the eighty eight neutrinos plus or
• 36:05
  Speaker 1: minus ten to the what eighty seven.
• 36:10
  Speaker 2: Seven pluster minus infinity.
• 36:12
  Speaker 1: Probably there's our pleasure minus infinity. All right, Well, let's
• 36:16
  Speaker 1: get to our last question of the episode, which is
• 36:19
  Speaker 1: about gravitational waves and can you serve one? So let's
• 36:23
  Speaker 1: get into that, but first let's take another quick break.
• 36:38
  Speaker 1: All right, Our last question of the day comes from
• 36:40
  Speaker 1: Klai wants to know about gravitational waves.
• 36:43
  Speaker 5: Howdy Daniel and Jorge. I was wondering how would feel
• 36:47
  Speaker 5: to be hit by a gravitational wave? We have detected
• 36:51
  Speaker 5: infinitely weak waves from Earth, but imagine if we were
• 36:56
  Speaker 5: close to two black holes revolving around each other and
• 36:59
  Speaker 5: eventually colliding and merging. How would it feel to get
• 37:03
  Speaker 5: hit by a gravitational wave? And would it be the
• 37:07
  Speaker 5: same as a wave? And finally, would your organs be damaged?
• 37:11
  Speaker 1: Interesting question. It sounds like Clay is planning a trip. Perhaps.
• 37:18
  Speaker 2: I think Klay wants to experience the universe, wants to
• 37:21
  Speaker 2: feel gravitation waves, not just read about it online.
• 37:25
  Speaker 1: Well, I think one of the things is that, first
• 37:27
  Speaker 1: of all, we're all experiencing gravitation waves right now.
• 37:30
  Speaker 2: Right, Yeah, that's true. Gravitational waves are everywhere. They fill
• 37:33
  Speaker 2: the universe because they're generated anytime any mass is accelerated.
• 37:38
  Speaker 2: So you're in orbit, you're generating gravitational waves. You get
• 37:42
  Speaker 2: out of bed, you're generating gravitational waves. Gravitational waves are everywhere, right.
• 37:47
  Speaker 1: We're experiencing them. We're generating them like if a car
• 37:50
  Speaker 1: accelerates in front of me, technically gonna feel or I'm
• 37:55
  Speaker 1: going to experience the gravitational wave generated by the car.
• 37:58
  Speaker 2: Right, It's very hard to feel these things because they're very,
• 38:02
  Speaker 2: very gentle. Remember that gravity is like the dominant force
• 38:06
  Speaker 2: and the structure of the universe, but it's also the
• 38:07
  Speaker 2: weakest force, if you even call it a force, so
• 38:10
  Speaker 2: much weaker than the forces that hold your body together
• 38:12
  Speaker 2: for example.
• 38:13
  Speaker 1: Right, they're super mellow, hard to detect, but we can
• 38:17
  Speaker 1: detect some of the ones that come from deep in
• 38:19
  Speaker 1: outer space, that come from black holes or heavy things
• 38:23
  Speaker 1: circling each other and then colliding.
• 38:25
  Speaker 2: Exactly. The way to detect gravitational waves is to look
• 38:27
  Speaker 2: for extremely loud sources of them, things that make very
• 38:31
  Speaker 2: dramatic gravitational waves. And so two black holes, which are
• 38:35
  Speaker 2: two enormous masses orbiting each other very very quickly just
• 38:39
  Speaker 2: before they collide, are very loud sources of gravitational waves.
• 38:44
  Speaker 2: So even though we're very far from them, we can
• 38:46
  Speaker 2: be like a billion light years away, we can still
• 38:49
  Speaker 2: detect those gravitational waves here on Earth with super sensitive detectors.
• 38:54
  Speaker 1: Right here on Earth. By the time that they get
• 38:56
  Speaker 1: to us, they're super weak because I guess, like a
• 38:58
  Speaker 1: ripple in a laketational waves get weaker as they expand
• 39:02
  Speaker 1: right from their source.
• 39:03
  Speaker 2: Yeah, as you get further from the source, they get
• 39:05
  Speaker 2: weaker and weaker.
• 39:06
  Speaker 1: Right, And as you said, the ones we're detecting now
• 39:08
  Speaker 1: with LIGO, which is the big physics instrument we have
• 39:11
  Speaker 1: here on Earth, those happen billions of light years away.
• 39:15
  Speaker 1: And I think the Khalist question is, like, what if
• 39:18
  Speaker 1: you're closer to that source of gravitational waves, Like, what
• 39:22
  Speaker 1: if you're right next to those two black holes glide in?
• 39:25
  Speaker 1: What would it feel like to have this giant gravitation
• 39:28
  Speaker 1: wave pass three?
• 39:29
  Speaker 2: Yeah, it's a really cool question to think about it.
• 39:31
  Speaker 2: I think we should like zoom in on what happens
• 39:34
  Speaker 2: first to like individual particles in your body, and then
• 39:37
  Speaker 2: think about what that would feel like.
• 39:40
  Speaker 1: There's a way. Wait, but the scenario is how close
• 39:42
  Speaker 1: am I to these gravitational waves?
• 39:43
  Speaker 2: So imagine we're just like a few tens of thousands
• 39:46
  Speaker 2: of kilometers away from these two black holes that are
• 39:49
  Speaker 2: orbiting each other.
• 39:50
  Speaker 1: Aren't black holes usually bigger than a few tens of
• 39:53
  Speaker 1: thousands of kilometers or are you imagining like two small ones?
• 39:56
  Speaker 2: Well, the kind of collisions we've seen are between black
• 39:59
  Speaker 2: holes that have like thirty to fifty solar masses, and
• 40:02
  Speaker 2: those have an event horizon radius of like one hundred
• 40:04
  Speaker 2: kilometers or less, So if you're thirty thousand kilometers away,
• 40:08
  Speaker 2: you're definitely not inside the event horizon.
• 40:10
  Speaker 1: Okay, so these are pretty small black holes.
• 40:12
  Speaker 2: Yeah, but these are the kinds of black holes we've
• 40:14
  Speaker 2: been able to see collide.
• 40:16
  Speaker 1: Ooh, all right, so then we're a few tens of
• 40:18
  Speaker 1: thousands of kilometers away from these two black holes smashing
• 40:22
  Speaker 1: into each other exactly.
• 40:23
  Speaker 2: And on a human, if you're like thirty fifty thousand
• 40:27
  Speaker 2: kilometers away from two black holes that have like the
• 40:29
  Speaker 2: mass of thirty or fifty times the sun, then you're
• 40:33
  Speaker 2: going to feel what's called a strain of about one millimeter.
• 40:37
  Speaker 2: The strain is how much your body is getting squeezed
• 40:40
  Speaker 2: by the gravitational wave. And this is what we measure
• 40:43
  Speaker 2: also here on Earth with LEGO, we have these innerferometers,
• 40:46
  Speaker 2: these very long laser legs that get squeezed and lengthened
• 40:50
  Speaker 2: as the gravitational wave passes by. The ones here on
• 40:53
  Speaker 2: Earth are so faint that the measure strains of like
• 40:56
  Speaker 2: one times ten to the negative twenty one, which means
• 40:59
  Speaker 2: that like the two mile leg of the inferometer gets
• 41:02
  Speaker 2: shorter by that factor. It's a really really tiny factor.
• 41:05
  Speaker 1: But unless how much like space is being stretched or compressed, right, Like,
• 41:10
  Speaker 1: not necessarily something in space, right, because it's something in
• 41:14
  Speaker 1: space is sort of holing on to itself. But you're
• 41:17
  Speaker 1: talking about the stretching of space itself.
• 41:20
  Speaker 2: Yeah, the changing of the distance between two particles. For example,
• 41:23
  Speaker 2: So imagine you have two particles and you're a few
• 41:26
  Speaker 2: tens of thousands of kilometers away from these black holes
• 41:29
  Speaker 2: that are e merging, and they're generating gravitational waves. What's
• 41:32
  Speaker 2: going to happen is they're going to change the distance
• 41:35
  Speaker 2: between the two atoms. Right, So, for example, that the
• 41:38
  Speaker 2: distance gets longer than those two atoms, if they were
• 41:41
  Speaker 2: like bound together somehow, then they're going to feel an
• 41:43
  Speaker 2: attractive force to pull them back to where they were
• 41:46
  Speaker 2: in equilibrium. If the gravitational wave is very slow, they're
• 41:51
  Speaker 2: going to be able to basically stain in equilibrium and
• 41:53
  Speaker 2: nothing really happens. But if the gravitational frequency is high,
• 41:57
  Speaker 2: if the sort of squeezing and pulling and pushing is fast,
• 42:01
  Speaker 2: they'll effectively feel a force and they might start to
• 42:03
  Speaker 2: oscillate back and forth. That's kind of what happens in Lego.
• 42:07
  Speaker 1: Like the stretching of space is kind of like how
• 42:10
  Speaker 1: much space wants to stretch you.
• 42:13
  Speaker 2: Yeah, the distance between those two particles or the two
• 42:16
  Speaker 2: mirrors in Lego gets longer or shorter based on the
• 42:19
  Speaker 2: gravitational wave. But then the interaction between the two particles,
• 42:22
  Speaker 2: or the structural strength of the thing, whatever, has a
• 42:25
  Speaker 2: natural length that it wants to be at, so to
• 42:27
  Speaker 2: try to return to that natural length. Like if you
• 42:30
  Speaker 2: imagine a spring between these two particles, you pull them apart, well,
• 42:33
  Speaker 2: the spring is going to pull them back.
• 42:35
  Speaker 1: Together, right, So then you're saying, like, if I'm a
• 42:37
  Speaker 1: few tens of thousands of kilometers from these black holes,
• 42:40
  Speaker 1: and I would feel about a one millimeter stretch in
• 42:43
  Speaker 1: my body, or space would want to stretch my body
• 42:45
  Speaker 1: about one millimeter mm hmm.
• 42:47
  Speaker 2: And based on the frequency, you're going to get shaken
• 42:50
  Speaker 2: by one millimeter. It's not like you just get pulled
• 42:53
  Speaker 2: by one millimeter in one direction and then you stay there.
• 42:56
  Speaker 2: A gravitational wave is a wave. It's oscillating, and depending
• 42:59
  Speaker 2: on the frequency, if it's like a fast wave or
• 43:02
  Speaker 2: a slow wave, it's going to shake you at that speed,
• 43:05
  Speaker 2: so it might like pull you in one direction and
• 43:07
  Speaker 2: then squeeze you in that direction and pull you in
• 43:09
  Speaker 2: the other direction. So there's this pulling, the stretching, and
• 43:12
  Speaker 2: the squeezing. So right now we're talking about the amplitude
• 43:15
  Speaker 2: about one millimeter, but the frequency of that is also important,
• 43:19
  Speaker 2: and that depends on the orbits of these black holes.
• 43:22
  Speaker 2: How many times are they passing around each other. That
• 43:24
  Speaker 2: determines the frequency of this gravitational wave. If you're nearby
• 43:28
  Speaker 2: these black holes, you're basically going to get shaken from
• 43:30
  Speaker 2: the inside.
• 43:31
  Speaker 1: Right, And you're saying kind of depending on the frequency,
• 43:35
  Speaker 1: it might be dangerous or not. Like if it was
• 43:37
  Speaker 1: shaking really slowly, you probably your body can probably adjust
• 43:40
  Speaker 1: to that shaking. But if it's shaking super fast, then
• 43:44
  Speaker 1: it might scramble your insides.
• 43:46
  Speaker 2: You might scramble your insides. You might also experience it
• 43:49
  Speaker 2: in a weird way, like it might be like being
• 43:52
  Speaker 2: at a concert. Sound waves at a concert also shake
• 43:55
  Speaker 2: your body and you experience them as sound. If you're
• 43:59
  Speaker 2: out in space near two black holes, you might literally
• 44:03
  Speaker 2: hear the gravitational waves because like the drums in your
• 44:07
  Speaker 2: ear will get shaken.
• 44:08
  Speaker 1: Whoa as put everything else in your body.
• 44:11
  Speaker 2: As would everything else, Just like at a concert. Right
• 44:13
  Speaker 2: when you're in the moshpit at that concert, your toes
• 44:16
  Speaker 2: are getting shaken, even though your ears are the only
• 44:18
  Speaker 2: ones actually transmitting sound to your brain. The same way
• 44:21
  Speaker 2: a gravitational wave can be squeezing and pulling on your
• 44:23
  Speaker 2: whole body, but your ears might be the only ones
• 44:26
  Speaker 2: picking it up.
• 44:27
  Speaker 1: I've never been in a moshpit, but I'll take your
• 44:29
  Speaker 1: word for it, so you might feel it. But is
• 44:33
  Speaker 1: it dangerous? Like if it's high frequency enough, and these
• 44:36
  Speaker 1: things are pretty high frequency by the time they smash together,
• 44:39
  Speaker 1: it's like super high frequency, right.
• 44:41
  Speaker 2: Yeah, they can get to be very high frequency. And
• 44:44
  Speaker 2: actually the frequency they experience is even higher than we
• 44:48
  Speaker 2: observe because there's gravitational time dilation. These black holes, of
• 44:53
  Speaker 2: course have super high curvature, and now one black hole
• 44:56
  Speaker 2: is near another one, it's experiencing the gravitational time dilation
• 44:59
  Speaker 2: of that black hole, so time is super slowed down.
• 45:03
  Speaker 2: So what we're observing is the slow down gravitational wave
• 45:07
  Speaker 2: being emitted by these event horizons. That's already taken into account.
• 45:11
  Speaker 2: If it wasn't, then the frequency would be much much higher.
• 45:15
  Speaker 1: Well, I guess from what we know of these smashing
• 45:18
  Speaker 1: black holes or the ones we've seen, then the frequency
• 45:20
  Speaker 1: we've seen, and how fast there actually are closer to
• 45:24
  Speaker 1: the source, would they actually kill you at this distance?
• 45:27
  Speaker 1: Like at some point they'll start to rip apart the
• 45:29
  Speaker 1: bonds between the proteins in your body, right, or you know,
• 45:34
  Speaker 1: it'll basically scramble your brain.
• 45:37
  Speaker 2: I don't think I can say. It depends a lot
• 45:39
  Speaker 2: on the internal biological friction, like how much energy is
• 45:43
  Speaker 2: actually going to get absorbed, and how squishy your body is,
• 45:46
  Speaker 2: how resilient it is, depends a lot on the exact
• 45:49
  Speaker 2: kind of tissue. I think all I can do is
• 45:52
  Speaker 2: treat your body as a sphere with ears and say
• 45:56
  Speaker 2: you'll probably hear it happening.
• 45:58
  Speaker 1: But you can probably make that calculation, right, Like you
• 46:00
  Speaker 1: can calculate this spignification point of a black hole, right,
• 46:04
  Speaker 1: like the point at which it would actually tear you
• 46:06
  Speaker 1: apart falling into a black hole. You can probably do
• 46:09
  Speaker 1: that for gravitational wave, right.
• 46:10
  Speaker 2: Yeah, But the energy that gets absorbed depends on this
• 46:13
  Speaker 2: internal friction. Like if there's no internal friction to your object,
• 46:17
  Speaker 2: it can get squeezed and squished and then be totally unharmed.
• 46:21
  Speaker 2: So how much energy is deposited, how much damage is
• 46:24
  Speaker 2: done depends entirely on the internal friction of that object.
• 46:28
  Speaker 2: It's not just dependent on the tidal forces.
• 46:31
  Speaker 1: Right right, But I imagine, I mean, we don't have
• 46:33
  Speaker 1: to do it now, or there's no pressure for you
• 46:35
  Speaker 1: to come up with an answer. But like, if you
• 46:37
  Speaker 1: could make the calculation for like a typical brain, what
• 46:40
  Speaker 1: are some of the maximum accelerations a brain can withstand
• 46:43
  Speaker 1: before it turns into you know, mush, and you can
• 46:46
  Speaker 1: maybe backtrack to find what kind of frequency of gravitation
• 46:50
  Speaker 1: waves would kill you.
• 46:51
  Speaker 2: Yeah, probably somebody who knows something about the brain could
• 46:53
  Speaker 2: figure that out.
• 46:56
  Speaker 1: What do we know about brains? We just use them.
• 46:59
  Speaker 2: I'm going to guess the answer is it depends, and
• 47:01
  Speaker 2: we don't know exactly.
• 47:03
  Speaker 1: You read my brain. That's exactly what I was.
• 47:06
  Speaker 2: Thinking, exactly. I just got a gravitational wave idea into
• 47:09
  Speaker 2: my brain.
• 47:10
  Speaker 1: But again, I feel like this is just firm standing
• 47:13
  Speaker 1: tens of thousands of kilometers away. May you say, maybe
• 47:17
  Speaker 1: we might survive this. I don't know, because don't these
• 47:20
  Speaker 1: things go pretty high frequency? Even a one millimeter strain
• 47:23
  Speaker 1: might be enough to mois your brain.
• 47:24
  Speaker 2: One milimeter strain is pretty big, so I think it
• 47:27
  Speaker 2: might be enough. I mean, I think one millimeter strain
• 47:29
  Speaker 2: is much more than you ever experienced at a concert.
• 47:32
  Speaker 2: Even very very high intensity sound waves don't actually like
• 47:36
  Speaker 2: move the molecules in your body by a millimeter. That's
• 47:39
  Speaker 2: a pretty huge displacement. And you've got lots of really
• 47:42
  Speaker 2: sensitive things inside your body that are much smaller than
• 47:45
  Speaker 2: one millimeter, So one millimeters squeezing and stretching could totally
• 47:48
  Speaker 2: destroy like really sensitive little biomachineries.
• 47:52
  Speaker 1: So smash bit, not moshpit, like your brain gets washed.
• 47:59
  Speaker 2: Yeah, I think it might be like being in a blender.
• 48:02
  Speaker 1: Great, then I imagine if you get closer to these
• 48:06
  Speaker 1: circling black holes and it just gets more dangerous, right,
• 48:09
  Speaker 1: because then the waves could get much more intense.
• 48:12
  Speaker 2: Exactly, the amplitude of the waves just grows as you
• 48:15
  Speaker 2: get closer. The strain gets larger and larger.
• 48:17
  Speaker 1: What if you're just a thousand kilometers away, how big
• 48:20
  Speaker 1: would the strain be.
• 48:21
  Speaker 2: Well, it goes like one over r a little, which
• 48:24
  Speaker 2: is a little bit weird, And so a thousand million
• 48:27
  Speaker 2: three times closer would be thirty times if you're like
• 48:31
  Speaker 2: thirty or ten times closer. If you're ten times closer,
• 48:34
  Speaker 2: it's going to be ten times as.
• 48:35
  Speaker 1: Strong, times times ten to the three. No, I mean
• 48:38
  Speaker 1: a q because because your are went down a tenth,
• 48:42
  Speaker 1: So then doesn't the intensity go up by a queue?
• 48:46
  Speaker 2: The strain goes like one over r oh linear? You
• 48:49
  Speaker 2: sure it's inverse linear? Yeah?
• 48:51
  Speaker 1: Oh, it's linear, all right, So then you would experience
• 48:54
  Speaker 1: it a one centimeter strain.
• 48:56
  Speaker 2: Yeah, ten times closer you get one centimeter strain.
• 48:58
  Speaker 1: Oh wait, yeah, that would be a lot.
• 49:02
  Speaker 2: That would definitely be a lot. CLI's asking how would
• 49:06
  Speaker 2: it feel to get hit by a gravitational wave? Would
• 49:08
  Speaker 2: your organs be damaged? It depends a lot on the
• 49:11
  Speaker 2: distance you get close enough, it could definitely scramble you. You
• 49:14
  Speaker 2: get not too close, then you could probably hear it,
• 49:17
  Speaker 2: like physically hear it without being destroyed. But I don't
• 49:21
  Speaker 2: know exactly where that line is, and I don't recommend
• 49:23
  Speaker 2: you figure it out.
• 49:24
  Speaker 4: Mmmm.
• 49:25
  Speaker 1: That's right. Keep it a thought experiment, Keep it a
• 49:27
  Speaker 1: brain experiment to save your brain. All right. Well, I
• 49:31
  Speaker 1: think that answers all of our questions. Some pretty interesting
• 49:34
  Speaker 1: ideas here. Overall, the picture is that the universe is
• 49:37
  Speaker 1: still mysterious. There's a lot we don't know, and there's
• 49:41
  Speaker 1: still a lot of questions we can ask about it
• 49:44
  Speaker 1: for us to explore.
• 49:45
  Speaker 2: But we love that you ask these questions, and we
• 49:47
  Speaker 2: love trying our best to answer them. We don't always
• 49:50
  Speaker 2: know the answer. That's sort of the game of physics,
• 49:52
  Speaker 2: figuring out where the edge of knowledge is and trying
• 49:54
  Speaker 2: to push it forward a tiny little.
• 49:56
  Speaker 1: Bit at least. That's one of the games one Daniel
• 49:58
  Speaker 1: can play.
• 50:00
  Speaker 2: What can we figure out if we have even more Daniels.
• 50:04
  Speaker 1: All right, well, we hope you enjoyed that. Thanks for
• 50:07
  Speaker 1: joining us. See you next time.
• 50:14
  Speaker 2: For more science and curiosity, come find us on social
• 50:16
  Speaker 2: media where we answer questions and post videos. We're on Twitter, Discorg, Insta,
• 50:21
  Speaker 2: and now TikTok. Thanks for listening, and remember that Daniel
• 50:25
  Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio.
• 50:29
  Speaker 2: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,
• 50:34
  Speaker 2: or wherever you listen to your favorite shows.