Speaker 1: Hey, Daniel, I have a new idea for how to
Speaker 1: solve quantum gravity.
Speaker 2: Oh my gosh, I'm so excited. I can't wait to
Speaker 2: hear it.
Speaker 1: Okay, just take any everyday object and add the word
Speaker 1: theory to the end of it.
Speaker 2: What that's it?
Speaker 3: Like?
Speaker 2: How did that work?
Speaker 1: You know? Like string theory or loop theory. Boom, I've
Speaker 1: solved quantum gravity.
Speaker 2: Those are already theories of quantum graphy.
Speaker 1: Okay, there are other objects we can use, like table
Speaker 1: theory or rug theory or pokemon theory. Boom. Anyone can
Speaker 1: be a quantum gravity physicist.
Speaker 2: Oh, I wish that's all there was to it.
Speaker 1: Wait, there's more.
Speaker 2: Physics isn't just about naming things, man, though, that is
Speaker 2: the hardest part.
Speaker 1: II am Foehammer, cartoonist and the author of Oliver's Great
Speaker 1: Big Universe.
Speaker 2: Hi. I'm Daniel. I'm a particle physicist and a professor
Speaker 2: at UC Irvine, and I hope that I'm around when
Speaker 2: quanm gravity gets figured out.
Speaker 1: Well, that's a massive wish. It's a little bit heavy
Speaker 1: on the responsibility for a theorists.
Speaker 2: I just want to be around so that I can
Speaker 2: hear what name you give it?
Speaker 1: It feels a little lazy of you. You're like, I
Speaker 1: wish that somebody else would solve this problem for me.
Speaker 1: When did you just get down to it, Daniel and
Speaker 1: solve it yourself.
Speaker 2: Not my job, man, not my job. I'm an experimentalist.
Speaker 1: I so you're a physicist.
Speaker 2: There are different flavors of physicists, you know, And I'm
Speaker 2: an experimentalist. I go out and discover weird stuff nobody
Speaker 2: can explain, and theorists job is to come up with
Speaker 2: ways to explain it.
Speaker 1: I feel like you're letting these imaginary or artificial boundaries
Speaker 1: get in the way of your true dreams. Daniel. Like,
Speaker 1: imagine if a serious said, oh, man, I wish I
Speaker 1: was an experimental physicist and could press but and stuff.
Speaker 1: Wouldn't you just be like, just press the button.
Speaker 2: No, No, you're right, those boundaries are artificial. Here in
Speaker 2: my department we have a theoretical physicist who's now running
Speaker 2: his whole experiment. And last year I wrote quite a
Speaker 2: few theory papers. So you're right, I'm cowering behind categories.
Speaker 1: That this could be you, Daniel. Just make up a
Speaker 1: theory and you can call yourself a theorist. Isn't that
Speaker 1: how it works.
Speaker 2: Yeah, podcast Theory of Physics.
Speaker 1: Dan, Yeah, Like, what's the minimum like in your department?
Speaker 1: Is there a minimum number of theories you have to
Speaker 1: come up with to be a theorist or number of
Speaker 1: publications one?
Speaker 2: Just one there? You have to do it once.
Speaker 1: That you can be a theorizer Today in this podcast,
Speaker 1: what's your theory of everything? Daniel mm?
Speaker 2: Yeah, I think it's the chocolate theory of everything.
Speaker 1: It's a dark theory or is it a white theory?
Speaker 2: I hope it's not a white theory. Oh my gosh,
Speaker 2: I'd be so disappointed in the universe.
Speaker 1: Turns out white chocolate is the secret to everything, and
Speaker 1: so you're going to just check.
Speaker 2: Out sweet and bitter at the same time.
Speaker 1: No, that's the whole point of white chocolate. It's not bitter.
Speaker 1: It's sweet for everybody.
Speaker 2: White chocolate sweet. But I would be bitter, just you.
Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain
Speaker 1: the Universe, a production of iHeartRadio.
Speaker 2: In which we do our best to understand this sweet,
Speaker 2: sweet universe without getting bitter about our favorite theories. We
Speaker 2: hope that everything that's out there in the universe, the
Speaker 2: tiny particles the huge black holes, the swirling oceans of magma.
Speaker 2: All of those things can be explained, can be understood,
Speaker 2: and we try to talk about all of them here
Speaker 2: on the podcast, where our goal is to fit all
Speaker 2: of those theories into your brain.
Speaker 1: That's right, because it is a sweet universe. It's also
Speaker 1: a sour universe, a bitter universe, and assault the universe
Speaker 1: and a umami universe. It's got all the flavors of
Speaker 1: mysteries and unknowns and questions that we can ask of it,
Speaker 1: and here on the podcast we sometimes try to answer
Speaker 1: those questions.
Speaker 2: That's right, Like string theory can explain the fundamental forces,
Speaker 2: but can it explain why people drink.
Speaker 1: Boba because it tastes sweet? I guess it's not bitter,
Speaker 1: doesn't have a mommy. I don't think it's truly and delicious.
Speaker 1: I mean, what's not to like? Isn't that the whole
Speaker 1: point of the universe to be truly and delicious?
Speaker 2: What's not to like the feeling of choking as you're
Speaker 2: trying to enjoy a beverage?
Speaker 1: I keep saying this time, but I feel like you're
Speaker 1: not drinking boba correctly. If somebody needs to show you
Speaker 1: the true theory of boba drinking.
Speaker 2: No, I know how to drink boba. You take the boba,
Speaker 2: you throw it in the trash, you move on with
Speaker 2: your life.
Speaker 1: Then you're that's not technically drinking, Danielle. Maybe maybe that's
Speaker 1: why you're not a theory. You don't know how to
Speaker 1: formerly theories.
Speaker 2: I'm generalizing drink. I have a new theory of drinking.
Speaker 2: Teach me, teach me a wise one.
Speaker 1: I'm not sure how we got to Boba's, but anyways,
Speaker 1: it is a wonderful universe, full of interesting mysteries and
Speaker 1: lots of interesting questions that you can ask of it,
Speaker 1: and that anyone can ask of it, even our listeners.
Speaker 2: Because science is not just about satisfying the curiosity of
Speaker 2: people who are paid to come up with theories or
Speaker 2: to do experiments or to fuzz those boundaries, but everybody
Speaker 2: out there. It's powered by human curiosity. It is fundamental
Speaker 2: desire to understand the nature of the universe we live in,
Speaker 2: to make it make sense. And so we encourage everybody
Speaker 2: out there to ask questions about how the universe works,
Speaker 2: try to fit all those various pieces together into their mind,
Speaker 2: and when they don't make sense, to write to us
Speaker 2: to questions at Danielanjorgey dot com, where every question gets
Speaker 2: an answer.
Speaker 1: That's right. Everybody has answers, and it seems like the
Speaker 1: more you learn about the universe, the more questions you
Speaker 1: have of it. And sometimes on this podcast we like
Speaker 1: to answer some of those questions.
Speaker 2: That's right. If you send me a question and I think, hm,
Speaker 2: I bet a lot of people want to hear the
Speaker 2: answer to that one, then we'll play for everybody on
Speaker 2: the podcast and even answer it.
Speaker 1: So to the on the podcast, we'll be tackling listener
Speaker 1: questions number fifty four. Is this like the studio fifty
Speaker 1: four version? Are we going to rock out and do
Speaker 1: a lot of drugs?
Speaker 2: I hope you're wearing something appropriate?
Speaker 1: Oh yeah, yeah, yeah, no, I'm always fashionable, Daniel. You
Speaker 1: don't even have to ask.
Speaker 2: Do you have your Studio fifty four pajamas on? Right now?
Speaker 1: I got my Studio fifty four cargo pants on and
Speaker 1: my Studio fifty four hoodie on? And what else do
Speaker 1: you need?
Speaker 2: Hmm? It sounds like you're kind of dressed the way
Speaker 2: you normally are.
Speaker 1: Yeah. I live in the eighties. I live the glaboral
Speaker 1: life of the eighties every day shooting we all.
Speaker 2: You found the perfect uniform and you're sticking with it.
Speaker 1: They stopped changing closing the eighties.
Speaker 2: Yes, and now you literally couldn't get them off once.
Speaker 1: I like something, there's no need to change in right.
Speaker 2: That's right. And what I like are hearing questions from
Speaker 2: listeners wondering what people out there do and do not
Speaker 2: understand about our universe. Sometimes people hear something on the
Speaker 2: podcast that doesn't make sense to them, then they write
Speaker 2: to me, or they read some other crazy article that
Speaker 2: doesn't quite fit in their brain, or they're just thinking
Speaker 2: deeply about the universe. Thanks everybody who writes in with
Speaker 2: your questions.
Speaker 1: Yeah, and so today we have three awesome questions from listeners.
Speaker 1: We have questions here about string theory, cosmic strings, and
Speaker 1: something that is not strings, but maybe aliens.
Speaker 2: Are you saying aliens couldn't be made of strings?
Speaker 1: Why do you want to string the listener along here
Speaker 1: and pretend that there's a connection between it and all
Speaker 1: of these questions.
Speaker 2: We'll find it. We'll find the connection.
Speaker 1: I'm sure there are aliens. They use strings. I mean
Speaker 1: they have to wear clothes. I guess maybe to they
Speaker 1: and for that they need strings, right, I know, yeah, yeah,
Speaker 1: Well let's jump right into it, Daniel. Our first question
Speaker 1: comes from Bruce and he has a question about string
Speaker 1: theory in The Big Bang.
Speaker 4: Hello Daniel and Jorey Burce labastered here from Lettingham, Saskatchewan, Canada.
Speaker 4: I was just wondering about string theory and the Big Bang?
Speaker 4: Is there any series around string theory and the Big Bank?
Speaker 4: If I understand correctly, the specific vibration of the strings
Speaker 4: creates specific particles. I'm thinking on the frequency of the
Speaker 4: strings that are everywhere changing to suddenly create the universe,
Speaker 4: and the particles sort of like they decayed down to
Speaker 4: the right energy level to create particles. Once again, you
Speaker 4: guys are awesome. Everything you do is great and I
Speaker 4: look forward to your answer.
Speaker 1: All right. This feels like taking two big questions and
Speaker 1: smushing them into one ginormous question or a little tiny question,
Speaker 1: depending on your perspective.
Speaker 2: No, I think it's a really cool question. It's trying
Speaker 2: to understand whether string theory gives us an idea of
Speaker 2: where the universe comes from and how we all ended
Speaker 2: up where we are hating or loving Buba?
Speaker 1: Boy, you really have it against Ba. What did Bulba
Speaker 1: do to you, Diana, did it actually try to choke you?
Speaker 2: Yes, the first time I had Boba, I almost choked
Speaker 2: on one. Yes, absolutely, and I will never forgive it.
Speaker 1: Well, it sounds more like the user error here than
Speaker 1: a fault of the product.
Speaker 2: To be honest, fair, fair, You know, we're talking about
Speaker 2: quantum gravity. In the last episode we had about it,
Speaker 2: we interviewed Nathan, who likes Boba even though his dad
Speaker 2: hates it. So that was just running through my mind.
Speaker 1: I see, I see, it's really stuck on your head.
Speaker 1: But there's a connection right the Big Bang in Boba.
Speaker 1: It's a little like fuzzy ball right at some point.
Speaker 2: Yes, it's dark, mysterious and kind of dangerous.
Speaker 1: And you can string Boba's long into to make a
Speaker 1: Boba pearl necklace.
Speaker 2: Boba's got two bes in it, just like the Big Bang.
Speaker 1: I think Boba's one word, Mmmm, it's got two b's
Speaker 1: in it. Though, I see this word has two bees,
Speaker 1: just like these two other two words have two bees.
Speaker 1: Got it? Got it?
Speaker 2: Okay? Connections Here, Bruce is asking actually a deep question
Speaker 2: about the nature of the universe. He wants to know
Speaker 2: basically what happened before the earliest time that we can understand.
Speaker 1: Yeah, And I think he's specifically asking whether, like, what's
Speaker 1: the connection between string theory and the origin of the universe. Like,
Speaker 1: we know about the Big Bang, and there's a theory
Speaker 1: called string theory. How does string theory a factor into
Speaker 1: the Big Bang? Or what does it say about the
Speaker 1: Big Bang?
Speaker 2: Yeah, string theory, like all theories of quantum gravity, basically
Speaker 2: pick up where the Big Bang leaves off. And there's
Speaker 2: a common misconception about the Big Bang. People think of
Speaker 2: the Big Bang as the universe starting from a single
Speaker 2: point and all that stuff then exploding out through space.
Speaker 2: But modern conception of the Big Bang doesn't talk about
Speaker 2: the actual very beginning of the universe. It says the
Speaker 2: universe right now is kind of cold and old, it's
Speaker 2: very dilute, but we know it's expanding. And so if
Speaker 2: you wind the clock backwards, what happens if you unexpand
Speaker 2: The universe gets denser, things closer together. It also gets hotter,
Speaker 2: and at some point it gets so hot and so
Speaker 2: dense that our current theories we don't think they'll work anymore.
Speaker 2: Because we have theories of general relativity that describes gravity
Speaker 2: and space and time, and we have theories of quantum
Speaker 2: mechanics that describes particles and all that fuzziness and uncertainty.
Speaker 2: And at some point, when the universe gets dense enough,
Speaker 2: then both of those theories come into play, and we
Speaker 2: don't know how to fit those together. For that, we
Speaker 2: need a theory of quantum gravity. So the Big Bang
Speaker 2: takes us back to some very hot, dense state that's
Speaker 2: like the limit of our understanding, but doesn't actually say
Speaker 2: what came before that. Quantum gravity tries to explain what
Speaker 2: happens when things get that hot and dense, and so
Speaker 2: it might give you some insight as to what came
Speaker 2: before the moment that we can describe up to the
Speaker 2: Big Bang.
Speaker 1: I wonder if there's a sort of like a distinction
Speaker 1: you can make between these theories, like is string theory
Speaker 1: or maybe just generally quantum theory a theory of matter,
Speaker 1: and maybe general relativity is more of a theory about
Speaker 1: space and time.
Speaker 2: General relativity is definitely about space and time, but it's
Speaker 2: also about matter and energy because it's about how all
Speaker 2: those things interact with each other. String theory is really
Speaker 2: a unified theory because it involves gravity. It also involves
Speaker 2: the other forces, like quantum mechanics can describe electromagnetism and
Speaker 2: the weak force and the strong force in terms of
Speaker 2: quantum mechanical objects, these quantum fields and ripples passing through them.
Speaker 2: General relativity can't explain any of that stuff, but string
Speaker 2: theory can reproduce general relativity and the quantum theory. So
Speaker 2: it really is a union of these two things. It
Speaker 2: explains all of it together.
Speaker 1: So string theory has things like this, the bending of
Speaker 1: space and the slowing down of time, all that is
Speaker 1: baked into the theory or did it just sort of
Speaker 1: like absorb general relativity.
Speaker 2: Yeah, that's a great question. One issue with string theory
Speaker 2: is that there's a lot of string theories. Like if
Speaker 2: you start putting these things together and saying, look, the
Speaker 2: universe is made out of these tiny vibrating strings that
Speaker 2: vibrate in many dimensions more than the ones that we see,
Speaker 2: you get lots of different possible ways for those string
Speaker 2: theories to build a universe. And we know that some
Speaker 2: of those correspond to the universe that we live in.
Speaker 2: We don't know how many of them and why this one.
Speaker 2: There's a whole big question there about like why there
Speaker 2: are so many string theories, but it is possible in
Speaker 2: some versions of string theory to reproduce general relativity and
Speaker 2: quantum mechanics, and so that lets you go back further
Speaker 2: in time than our current theories, back to where the
Speaker 2: universe was so hot and so dense that you need
Speaker 2: that theory of quantum gravity.
Speaker 1: So string theory does gerald relativity and quantum theory, but
Speaker 1: it's sort of not proven, right. It's just a sort
Speaker 1: of a theory, but it hasn't been confirmed yet.
Speaker 2: It has definitely not been confirmed. It only describes things
Speaker 2: that we cannot yet test. We can't create those conditions
Speaker 2: higher than the plank temperature essentially in order to test
Speaker 2: quantum gravity. Really yet, we had a whole episode about
Speaker 2: whether you could test quantum gravity with like tabletop experiments.
Speaker 2: There's some clever ideas there, but currently string theory is
Speaker 2: just a theory of quantum gravity. It's still got some
Speaker 2: mathema medical issues. Also, we can't describe like dark energy
Speaker 2: and the expansion very well. But it does give you
Speaker 2: a cool picture of how the universe might work if
Speaker 2: it's correct.
Speaker 1: Well, okay, so then it can do both things. Then
Speaker 1: what does it say about the Big Bang.
Speaker 2: It says something pretty cool. Actually, it tells you that
Speaker 2: the universe can't compress beyond a certain point, like there's
Speaker 2: a minimum size to these strings. General relativity has no
Speaker 2: problem compressing the universe infinitely until every part of space
Speaker 2: is infinitely dense. But when you fold the quantum nature
Speaker 2: of these strings in, it says, look, everything in the
Speaker 2: universe has made it these vibrating strings, and they have
Speaker 2: like a minimum size. That tells you the universe could
Speaker 2: never have gotten denser than a certain level.
Speaker 1: Wait, is that what it says? Or does it say
Speaker 1: that you can't have things that are smaller than that?
Speaker 1: But could the universe be smaller than the things it
Speaker 1: can have?
Speaker 2: Ooh wow, that's a debilosophical question. So first of all,
Speaker 2: we're not talking about the size of the universe. We're
Speaker 2: talking about density, right, We're talking about the whole universe,
Speaker 2: which could be infinite anyway, and could have always been
Speaker 2: infinite and could always be infinite. We talked about changing
Speaker 2: from high density in the early universe to low density now,
Speaker 2: so it's really more of a density than size. But
Speaker 2: on your question, I do think the universe has to
Speaker 2: be at least as big as the stuff in it?
Speaker 1: Why can it be compressed more than the things that
Speaker 1: it can have in it? Like, for example, my car
Speaker 1: can be compressed smaller than what I can fit in it.
Speaker 2: In order something to be in the universe, it has
Speaker 2: to have a location in the universe, which means the
Speaker 2: distance from one side of it to the other side
Speaker 2: of it has to exist, so that space exists, and
Speaker 2: so that's part of the universe. So therefore, the universe
Speaker 2: has to be at least as big as the stuff
Speaker 2: in it.
Speaker 1: Why can't it be smaller or more dense? Just like
Speaker 1: why can't my car be smaller than me?
Speaker 2: Well, if your car was smaller than you, you couldn't
Speaker 2: get in it.
Speaker 1: Yeah, but it'd still be a car. Like I could
Speaker 1: take my car and scrunch it down to the size
Speaker 1: of a basketball, still be my car. I just couldn't
Speaker 1: fit in it. But it doesn't mean that it's not
Speaker 1: my car.
Speaker 2: That's true. But the universe contains everything that's in the universe.
Speaker 2: So if you're in the universe, the universe is at
Speaker 2: least as big as you are. Even if your car
Speaker 2: has shrunk smaller than you are, right.
Speaker 1: Well, it could still have me in it, I would
Speaker 1: just be squeesced through a bulb.
Speaker 2: I see. Well, the thing about quantum strings is they
Speaker 2: think that there really is a minimum size there, like
Speaker 2: a quantum mechanical minimum beyond which you cannot shrink them.
Speaker 2: If you add another feature of quantum mechanics, which is
Speaker 2: time reversibility, then all the laws of physics seem to
Speaker 2: go equally well backwards and forwards in time. It naturally
Speaker 2: brings you to a bounce scenario where the universe infinitely
Speaker 2: far back in time may have been infinitely dilute, and
Speaker 2: then it gradually gathered together towards a hotter, denser state,
Speaker 2: and then when it reached the maximum density, it basically
Speaker 2: bounced back, expanding out again, and then then expanding out
Speaker 2: again and creating our universe.
Speaker 1: They called that the big bounce, Right.
Speaker 2: Yeah, that's like the big bounce. The big bounce comes
Speaker 2: in lots of different varieties, but some versions of string
Speaker 2: theory are very nicely compatible with this kind of big bounce,
Speaker 2: and it gives you a reason for the bounce. Right,
Speaker 2: Why didn't the universe just keep compressing until infinite density
Speaker 2: and go on and on and on the answer is,
Speaker 2: strings pushed back strings of a minimum length, which means
Speaker 2: a maximum density, and that is where the bounce comes from.
Speaker 1: M Does that mean that the era of time continues
Speaker 1: beyond the Big Bang?
Speaker 2: Yeah, it means that that earliest moment that we can
Speaker 2: describe with our current theories, that's what we typically describe
Speaker 2: as the Big Bang. We could extrapolate back further to
Speaker 2: some higher density but not infinite density, and then even
Speaker 2: back through that to when the universe is doing the
Speaker 2: inverse Big Bang.
Speaker 1: WHOA, And was that universe kind of like a mirror
Speaker 1: imagere of our universe just running backwards in time or
Speaker 1: is it a totally different universe?
Speaker 2: We think you should have the same laws of physics
Speaker 2: because it's built out of the same basic strings. But yes,
Speaker 2: it's running backwards through time if you're thinking about it
Speaker 2: in that direction. Really, the way to think about it
Speaker 2: is to start deep in the infinite past, running forwards
Speaker 2: in time as that universe is compressing. So that'd be
Speaker 2: a very different universe to live in, because that universe
Speaker 2: wouldn't be expanding like ours is.
Speaker 1: It would be shrinking, And would it have the same
Speaker 1: things like dark energy, which is in our side of
Speaker 1: the universe mirror expanding the universe, wouldn't it also have
Speaker 1: dark energy expanding it?
Speaker 2: Well, string theory can't always accommodate or explain dark energy,
Speaker 2: so that part is still a bit of a question
Speaker 2: mark where that comes from, where that's shrinking, and then
Speaker 2: expansion comes from originally, So that's still something to be
Speaker 2: figured out. As you can tell, this is all a
Speaker 2: little bit sketchy because string theory itself has so many
Speaker 2: varieties that there's like a thousand different directions people are
Speaker 2: exploring it in, and so if you read up on
Speaker 2: like string cosmology, you'll see this scenario, but also like
Speaker 2: five hundred other ideas for how strings could explain the
Speaker 2: Big Bang or what came before it?
Speaker 1: Did you just call it extreme cosmology?
Speaker 2: String cosmology?
Speaker 1: String or extreme?
Speaker 2: Yeah? It is pretty extreme.
Speaker 1: Also they both sounds pretty exciting. Oh, I say it's
Speaker 1: string cosmology, not extreme chrismology exactly.
Speaker 2: But you know, Bruce is wondering, is it possible for
Speaker 2: those strings in the very early universe to decay down
Speaker 2: and create our particles? And the answer is yes, absolutely.
Speaker 2: If string theories right, then the universe was much denser
Speaker 2: than even our quantum field theory of particles can describe
Speaker 2: a moment when everything was these crazy bouncing strings.
Speaker 1: And then those strings became quantum particles, and then those
Speaker 1: quantum particles became us, and then someone became boba balls
Speaker 1: which try to kill Daniel apparently unsuccessfully. Unsuccessfully so far,
Speaker 1: so far. They'll get you yet, Daniel, They'll sneak up
Speaker 1: on you.
Speaker 2: That's a horror movie right there, a man being followed
Speaker 2: by bubba.
Speaker 1: That would be scary for like three people, yeah, including you,
Speaker 1: I guess.
Speaker 2: But it is possible that we could one day know
Speaker 2: more than just speculate, because these theories do make some
Speaker 2: predictions the very early universe. It's expansion and all the
Speaker 2: dynamics are predicted to leave gravitational way bouncing around the universe.
Speaker 2: These are called primordial gravitational waves. If those are there
Speaker 2: and we can pick them up and measure them, we
Speaker 2: could learn something. But what happened in that early state
Speaker 2: before quantum field theory can describe basically before the Big Bang?
Speaker 1: Well, so I guess in this version gravitational waves are
Speaker 1: not made out of particles.
Speaker 2: Then, no, they're not boba particles or anything. They're real
Speaker 2: ripples in space time. But these would be very very subtle.
Speaker 2: There was an experiment a few years ago they claim
Speaker 2: to have measured primordial gravitational waves, but it turns out
Speaker 2: they were just measuring dust. It's a hard problem.
Speaker 1: All right. Well that's the answer for Bruce. What a
Speaker 1: string theory say about the Big Bang? It says that
Speaker 1: maybe the Big Bang just came from the big bounce
Speaker 1: mm hmm, and that from that came quantum particles in
Speaker 1: quantum things, including quantum theories, extreme theories of the use.
Speaker 1: That's right, extreme and string both alike. All Right, thanks
Speaker 1: Bruce for that question. Let's get to our second question.
Speaker 1: This one is about cosmic strings, which has nothing to
Speaker 1: do with string chrismology at all, like at all. It's
Speaker 1: a totally different thing, super interesting. So let's get to
Speaker 1: that question. But first let's take a quick break. Right.
Speaker 1: We're answering listener questions here today, and our second question
Speaker 1: is pretty cosmic, dude. It's about cosmic strings, and it
Speaker 1: comes from Dane.
Speaker 5: Hy Daniel and Jorge in articles about the newly discovered
Speaker 5: big ring megastructure. I've seen cosmic strings mentioned several times
Speaker 5: as a possible cause if cosmic strings even exist, what
Speaker 5: happens when one intersects a black hole. Also, what happens
Speaker 5: when normal matter contacts a cosmic string? Is it pulled
Speaker 5: into the string? Is a cosmic string effectively a black line?
Speaker 5: Also is there a stable orbital path around a string?
Speaker 5: If so, what would that be? A ring, a spiral,
Speaker 5: or corkscrew something else. Thanks for any clarification you can provide.
Speaker 5: I think cosmic strings are really weird.
Speaker 1: All right, an interesting question here, and again, cosmic strings
Speaker 1: have nothing to do with string theory.
Speaker 2: Yeah, it's almost as if the names and physics are
Speaker 2: just not very well thought out.
Speaker 1: A little bit. I mean I've sort of been saying
Speaker 1: that for five years.
Speaker 2: Yeah, I think you put it very well. Cosmic strings
Speaker 2: have nothing to do with string cosmology. Totally separate questions.
Speaker 1: But they could be related, right, Like, for example, string
Speaker 1: theory could account for cosmic strings.
Speaker 2: For example, if string theory is correct, then it accounts
Speaker 2: for everything. So then yes, cosmic strings are made out
Speaker 2: of tiny quantum strings.
Speaker 1: Okay, it's like a string made out of strings.
Speaker 2: Yeah, exactly. Like if string theory is right, then the
Speaker 2: yard that made your sweater is also made out of
Speaker 2: quantum strings, so you're wearing like a string.
Speaker 1: Theory sweater right, right, but we don't know. I guess yes,
Speaker 1: there hasn't been that connection yet. But cosmic strings is
Speaker 1: something that comes out of just general relativity.
Speaker 2: Right, Cosmic strings is an idea that does come out
Speaker 2: of general relativity, but it's also related to quantum mechanics.
Speaker 2: It has to do with how the universe is cooling
Speaker 2: and how the laws of physics and the sort of
Speaker 2: state of space itself changes and cracks as the universe cools.
Speaker 1: Well, all right, well maybe break it down for us.
Speaker 1: What is a cosmic string?
Speaker 2: So cosmic string is like a topological defect in space.
Speaker 1: It's a theoretical concept first of all, right, like nobody's
Speaker 1: sen one. It's just something people think might exist out there.
Speaker 2: Yeah, it's just an idea so far. It would be
Speaker 2: interesting because they're like a boundary. They're like a spot
Speaker 2: where space behaves differently, not like the laws of physics
Speaker 2: themselves are different, but it's like space is in a
Speaker 2: different phase. If you think about the universe from the
Speaker 2: very initial days, things are hot and dense. You can
Speaker 2: use a sort of certain set of laws to describe it,
Speaker 2: the same way that you use like the ideal gas
Speaker 2: law to describe water when it's a gas, and you
Speaker 2: use fluid dynamics to describe it when it's a fluid,
Speaker 2: and use like crystal theory describe it when it's a lattice.
Speaker 2: Things are a different temperature, you have different effective laws
Speaker 2: that describe them. We think the universe is the same way.
Speaker 2: And as the universe cools, as things expand and get
Speaker 2: more dilute, different effective laws take over. And so the
Speaker 2: universe sort of has different phases.
Speaker 1: Phases with a pH right like phase like solid or liquid.
Speaker 2: Yeah, phases, not faces. I don't know if there are
Speaker 2: any faces in the universe except for the one on Mars.
Speaker 2: But yeah, we think about phases more generally than just
Speaker 2: like the phases of matter. Businists think about them as
Speaker 2: like regions where your laws of physics are applicable, because
Speaker 2: there's always boundaries to where your laws work. Just like
Speaker 2: we were talking about how quantum field theory works up
Speaker 2: to a certain temperature and beyond that it doesn't work anymore.
Speaker 2: So there's a phase in which you can talk about
Speaker 2: quantum fields, and beyond that it's sort of nonsense.
Speaker 1: And so it is that after the Big Bang, everything
Speaker 1: was super hot and things kind of settle down, and like,
Speaker 1: for example, around us, the universe settle into a particular phase,
Speaker 1: particular set of laws or arrangement of the quantum fields.
Speaker 1: But maybe next door to us, a few thousand or
Speaker 1: bazillion light years away, maybe it started settling in a
Speaker 1: totally different set of laws or phase.
Speaker 2: Because as the universe cools, there's a few different ways
Speaker 2: that it could cool down. It's like a ball rolling
Speaker 2: down a hill, but that hill has interesting features in it,
Speaker 2: so maybe it gets stuck on a shelf, or maybe
Speaker 2: it goes all the way down to the valley.
Speaker 1: And is there an infinite number of bases of the
Speaker 1: universe that the universe can be or is there a
Speaker 1: like three or four.
Speaker 2: Well, we don't really know. It depends on the nature
Speaker 2: of all those quantum fields. For example, we know that
Speaker 2: in our portion of the universe we have not settled
Speaker 2: into like the lowest energy possible state of the universe.
Speaker 2: Some of the fields that fill space got stuck, like
Speaker 2: the Higgs field. The Higgs field has a lot of
Speaker 2: energy in it, and that's why we have mass. And
Speaker 2: when things interact with the Higgs field, there's a lot
Speaker 2: of energy stored in that field, it hasn't fully relaxed,
Speaker 2: and we talked about how if it did spontaneously collapse,
Speaker 2: that would change the nature of physics. It would lead
Speaker 2: to a new phase of the universe in which the
Speaker 2: same fundamental laws might apply. But you know, everything we've
Speaker 2: learned about atomic physics and chemistry and whatever wouldn't apply.
Speaker 2: So in our region of the universe we're in a
Speaker 2: certain phase, like space is cooled in a certain way.
Speaker 2: Are there different options? We don't really know, because we
Speaker 2: don't fully understand the nature of the Higgs field and
Speaker 2: the other fields that might be out there once for
Speaker 2: dark matter or dark energy. There's lots of potential fields
Speaker 2: out there in the universe.
Speaker 1: So there might be part of the universe out there
Speaker 1: beyond the observable universe, right, because as far as we know,
Speaker 1: the observable universe is the same phase. Right, I imagine,
Speaker 1: as far as.
Speaker 2: We can tell, the same laws of physics to apply
Speaker 2: everywhere in the observable universe. So yeah, most likely these
Speaker 2: things would exist past the observable universe.
Speaker 1: Then the idea is that maybe beyond the observable universe,
Speaker 1: there's in the same universe, there's another phase expanding or
Speaker 1: growing or settling, just like we are, and at some
Speaker 1: point they have to meet. And if they meet, is
Speaker 1: it like a big disaster or can both types of
Speaker 1: universes coexists next to each other?
Speaker 2: Well, the theory of cosmic strings is that they can coexist,
Speaker 2: and then you get this weird boundary, and that's the
Speaker 2: cosmic string. It's like a crack in space where the
Speaker 2: laws are different on one side and the other. These
Speaker 2: can be like two dimensional, like a whole surface where
Speaker 2: the laws are on different on one side and the other.
Speaker 2: They could even be like one dimensional, and that's where
Speaker 2: the idea of cosmic string comes in. These like long,
Speaker 2: weird cracks in space, but the laws are a little
Speaker 2: bit different just in that like one feptometer wide cosmic
Speaker 2: string that could be like ninety billion light years long.
Speaker 1: Well, I guess I'm thinking of like bubbles. Like if
Speaker 1: we're in a bubble and there's a bubble next to us,
Speaker 1: where the two bubbles meet, you get a wall basically, right,
Speaker 1: mm hmmm. Is that what we're talking about in terms
Speaker 1: of the interface between two phases, Like it could be
Speaker 1: a wall, or sometimes if you get like three bubbles,
Speaker 1: then you can sort of get a line between the
Speaker 1: three bubbles. Is that what you mean by a string?
Speaker 2: Yeah, here we're talking about a line, and the bubble
Speaker 2: analogy mostly works.
Speaker 1: Okay, let's go with boba. If it got three boba balls, it's.
Speaker 2: My mental kryptonite. I can't even think now. I'm just
Speaker 2: worried about choking the whole time.
Speaker 1: Get over it, Daniel, it's the new thing.
Speaker 2: I can't. I can't that what roughly works, the boba analogy.
Speaker 2: But it is possible for space to crack as it's
Speaker 2: cooling in this sort of uneven way and create these
Speaker 2: one dimensional ripples in space.
Speaker 1: Whoa what does that mean?
Speaker 2: Like?
Speaker 1: How can a string have two sides to it?
Speaker 3: Right?
Speaker 1: Because if you're saying it's the intersection between two universes,
Speaker 1: like which side is what.
Speaker 2: This scenario we have like a cosmic wall, give an
Speaker 2: interface between two portions of three D space. But you
Speaker 2: can also get space just cooling in this way where
Speaker 2: you have a line that's a different phase and the
Speaker 2: rest of space is all the same. So it's like
Speaker 2: a tube of space that's different than the rest of it.
Speaker 1: Oh wait, wait, wait, does a cosmic string is more
Speaker 1: like a cosmic tube.
Speaker 2: Yeah, because it's not really one dimensional. It's like one
Speaker 2: femtometer wide but very very long. So it's like a
Speaker 2: cosmic hair or something that's very very long.
Speaker 1: Whoa, and inside of that hair is a whole different universe.
Speaker 2: Yeah, exactly, And they think they're probably higher energy. The
Speaker 2: universe hasn't cooled in those places as much. It's like
Speaker 2: hotter and denser. So these things, if they exist, they
Speaker 2: are gravitational objects because they're immensely dense. They're basically stuffed
Speaker 2: filled with original primordial energy. Imagine like a tube of
Speaker 2: the original hot dense universe that's never cooled. It got
Speaker 2: like stuck at some hot dense statement's still around.
Speaker 1: Like it somehow got trapped, right, is that the idea
Speaker 1: like maybe like the universe started settling into our kind
Speaker 1: of universe all around it, and as those things grew,
Speaker 1: there's a certain amount of primordial energy you got trapped
Speaker 1: and squeeze into uh, basically spaghetti.
Speaker 2: Yes, exactly, cosmic pasta.
Speaker 1: Yeah, that's a better name for it. Cosmic city or rigatoni.
Speaker 1: I don't know. Oh no, wait, bugatoni, that's the right, right,
Speaker 1: that would be the rest Well.
Speaker 2: Not an expert sounds good. All right, So now I
Speaker 2: think we're finally ready to answer Dane's question.
Speaker 1: Oh right, right, what was this question again?
Speaker 2: What happens when a cosmic string hits a black hole?
Speaker 1: Oh?
Speaker 2: Okay, he wants to throw that spaghetti against the wall.
Speaker 1: I see he wants to throw the spaghetti against like
Speaker 1: a meat ball.
Speaker 2: Yeah. And the short answer is, we're not sure because
Speaker 2: cosmic strings are features of a kind of theory of
Speaker 2: quantum gravity, because as you hear, they're all about how
Speaker 2: quantum fields are cooling, but they also involve space. You know,
Speaker 2: you have energy density deformation of space, and black holes
Speaker 2: are a feature of general relativity. They don't know how
Speaker 2: to talk to quantum mechanics, and so we're not exactly
Speaker 2: sure what would happen because we don't really have a
Speaker 2: full theory of quantum gravity that would explain how quantum
Speaker 2: fields behave near a black hole.
Speaker 1: Well, I guess the question are they both even compatible?
Speaker 1: Like does the theory that predict cosmic strings also predict
Speaker 1: black holes or are they sort of mutually exclusive.
Speaker 2: Now, in the theory where you have cosmic strings, you
Speaker 2: also are allowed to have black holes. Yes, we don't
Speaker 2: know if cosmic strings are real, we could look for
Speaker 2: them with gravitational lensing gravitational waves of their own, because
Speaker 2: we think they're dynamic. They can like wiggle and whip
Speaker 2: around and stuff. But of course we've never seen one.
Speaker 1: Well technically, we don't even know if black holes are real.
Speaker 2: Yeah, technically that's true. There are some very compact massive objects,
Speaker 2: but we don't know if they actually are general relativistic
Speaker 2: black holes or something else.
Speaker 1: All right, well, then what would happen if you have
Speaker 1: this crack the spaghetti of super primorial energy hitting a
Speaker 1: black hole. Wouldn't the black hole just win?
Speaker 2: Probably that's what would happen, because black holes always win.
Speaker 2: I mean, they are event horizons. So cosmic strings and
Speaker 2: the cosmic string is just like a tube of super
Speaker 2: high energy density, and so it probably just gets slurped
Speaker 2: up and make it for like a really monster black hole.
Speaker 1: Or could the string maybe like slice the black hole apart?
Speaker 1: Is that a possibility? Like it? Because these strings aren't
Speaker 1: just sitting out there, they're also bending space and time
Speaker 1: around them, right like they're super extreme. I think we've
Speaker 1: talked about maybe like doing a lub arond one of
Speaker 1: these and going back in time and things like that.
Speaker 1: Couldn't one of these strings just kind of like disrupt
Speaker 1: a black hole.
Speaker 2: There's one way to theoretically go back in time, which
Speaker 2: involves doing orbits around an infinite string of cosmic dust,
Speaker 2: But that's a different kind of string. That's a third
Speaker 2: kind of string. But could cosmic strings slice a black
Speaker 2: hole in half? I don't think so, because cosmic strings
Speaker 2: are just energy density. Although there are energy density where
Speaker 2: the rules of the universe are in a different phase,
Speaker 2: those quantum fields are still very, very high, but there's
Speaker 2: something about them that's preserving that there's like a crack
Speaker 2: in space itself, is an interface there that's keeping this
Speaker 2: from just like diffusing out into space, and so the
Speaker 2: rules are a little bit different. But my money would
Speaker 2: be on the cosmic string getting gobbled by the black hole.
Speaker 2: You never bet against the black hole.
Speaker 1: But a cosmic string, isn't it super long? So would
Speaker 1: it just get split in half? Or what would happen?
Speaker 1: Would it get disrupted by the black hole and then
Speaker 1: rejoin up again.
Speaker 2: They can be super duper long, like maybe one hundred
Speaker 2: billion light years, but if a black hole hits the
Speaker 2: middle of it, it would just start slurping it from both sides.
Speaker 2: It's like if you eat a piece of spaghetti from
Speaker 2: the middle and you can just slurp both ends in.
Speaker 1: Oh, this cosmic string is a thing, like you can move.
Speaker 2: Yes, yeah, they can whip around and slide through space
Speaker 2: absolutely and make gravitational waves, which is how we might
Speaker 2: one day be able to detect them.
Speaker 1: It would slur But interesting. But isn't it like a
Speaker 1: feature of space?
Speaker 2: Yes, but everything's a feature of space. You're a feature
Speaker 2: of space. I'm a feature of space, right.
Speaker 1: Like I guess I mean, like when it gets slurred
Speaker 1: by the black hole, Like, can it move through space?
Speaker 1: If it's a feature of space.
Speaker 2: You can move through space the same way that we can. Right,
Speaker 2: We're just like our energy slides through the quantum fields
Speaker 2: that feel all of space. Cosmic strings can also move,
Speaker 2: so it's sort of like persistent in that way. They
Speaker 2: don't just diffuse out into nothing. They persist and move
Speaker 2: through space, keeping their structure m.
Speaker 1: All right. So then I guess that answers Dan's question.
Speaker 1: Your best guess is that the black hole wins. It
Speaker 1: slurps up the cosmic string like a string of bugatoni pasta.
Speaker 2: That's right, because as dense as the cosmic string is,
Speaker 2: it's not dense enough to make its own black hole.
Speaker 2: So it's probably less dense than the black hole, and
Speaker 2: that's why the black hole wins. And even if the
Speaker 2: cosmic string was dense enough to make like a black
Speaker 2: line of singularities, that would also just be a black hole,
Speaker 2: and black hole plus black hole means black hole, it.
Speaker 1: Would be a black line or black pasta.
Speaker 2: Squid pasta cosmic squid pasta.
Speaker 1: There you go, a new recipe for the universe. All right, well,
Speaker 1: thank you Dane for that question. Now let's get to
Speaker 1: our third question, and this one is about Daniel's favorite topic,
Speaker 1: aliens and also nano things, and so let's get to
Speaker 1: that question. But first let's take a quick break. All right,
Speaker 1: we're answering listener questions here today, and our last question
Speaker 1: of the day comes from I'll be.
Speaker 3: Hi, Daniel and Jorge. In trying to communicate with extraterrestrials,
Speaker 3: we need to demonstrate that our signals are intelligent. We
Speaker 3: can't broadcast, say the speed of light or the ground
Speaker 3: energy of hydrogen using our preferred units like meters per
Speaker 3: second or electron volts because who's to say that ET
Speaker 3: doesn't measure speeds in quad lutes per nano. Now, how
Speaker 3: do we then demonstrate in a unit free or natural
Speaker 3: way that we know stuff?
Speaker 1: All right? Interesting question. I feel like this is a
Speaker 1: question about how to talk to aliens.
Speaker 2: Yeah, basically, how do we convince aliens that we're smart,
Speaker 2: that we're here. How do you send a message to
Speaker 2: aliens that when they read it they're like, oh yeah,
Speaker 2: those guys know they're doing or there are even people
Speaker 2: out there.
Speaker 1: Like how do we pass the test? Like, if you
Speaker 1: want to talk math to aliens, I think obvious question
Speaker 1: is like what sort of units would you use if
Speaker 1: you can? Are there like units that they would recognize?
Speaker 2: Yeah, it's a really cool question. There's a couple directions
Speaker 2: to go with this, like could you come up with
Speaker 2: numbers that don't need units? Are there physical numbers in
Speaker 2: the universe that are unit lists? Because He's right, units
Speaker 2: are things we made up, you know, Like the speed
Speaker 2: of light is three times ten of the eight meters
Speaker 2: per second, But that number three times ten of eight
Speaker 2: is only that number because of the length of a
Speaker 2: meter in the length of a second. If you change
Speaker 2: that to something else, the speed of light would be
Speaker 2: a different numbers. You can't just send that number without
Speaker 2: explaining where the units are. The units are just something
Speaker 2: we invented, right.
Speaker 1: Yeah, And I think we don't even know exactly what
Speaker 1: a meter is or it's like it's a little bit
Speaker 1: somewhat arbitrary or changeable.
Speaker 2: It used to be that a meter was length of
Speaker 2: some platinum rod in Paris, But then people finally realize
Speaker 2: that's ridiculous because Paris has different weather, and so the
Speaker 2: rod gets longer and shorter, and we all get like
Speaker 2: taller and shorter as that happens. Now they define the
Speaker 2: meter in terms of the speed of light, how far
Speaker 2: light goes in a certain amount of time.
Speaker 1: Even the units of time are oursho arbitrary, right, Like
Speaker 1: a second which is one sixty eight of a minute
Speaker 1: and sixty of an hour and twenty fourth of a day.
Speaker 1: That's arbitrary, right, like we could have twenty four hours
Speaker 1: in a day.
Speaker 2: The units of time are arbitrary, You're absolutely right. We
Speaker 2: just made them up. But they are all so physical,
Speaker 2: Like we define the second in terms of oscillations of
Speaker 2: an atom, and when atom oscillates a certain number of times,
Speaker 2: we call that a second. That's a new definition of
Speaker 2: a second. So one approach to making something universal is
Speaker 2: to say, let's just get rid of units altogether, and
Speaker 2: we can talk about that. The other approach is to
Speaker 2: make the units physicals and say, like, look, here's a
Speaker 2: very natural choice for a clock. Let's use that as
Speaker 2: our definition of time and hope the aliens follow along.
Speaker 2: That's actually what Carl say, you can try. I had
Speaker 2: to do on the Pioneer plaque. This plaque that went
Speaker 2: on the Pioneer probe and was sent out into deep
Speaker 2: space and is right now zooming out towards aliens.
Speaker 1: Yeah. I think that was in that movie Contact too,
Speaker 1: wasn't it. Like they use the hydrogen atom as a
Speaker 1: sort of like baseline, and you make a drawing of
Speaker 1: the hydrogen atom and hopefully the aliens will be like, oh,
Speaker 1: that's a hydrogen atom, and from there you can kind
Speaker 1: of figure out units of time and length.
Speaker 2: Yeah, exactly. There's a spin flip transition. The electron has
Speaker 2: a certain spin and it can sometimes flip from one
Speaker 2: spin to the other spin, and it's very well known
Speaker 2: time from a very basic thing in the universe. Hydrogen
Speaker 2: is like most of the universe. So if you can
Speaker 2: somehow describe hydrogen and describe this spin flip and communicate
Speaker 2: to the aliens like, look, can we all agree that
Speaker 2: this is a basic unit of time, then you can
Speaker 2: start to talk about things that take time. And then
Speaker 2: you can use like the speed of light. The speed
Speaker 2: of light helps you relate meters and seconds, right, relates
Speaker 2: distance and time, and so from there you could build
Speaker 2: up what you imagine would be me be a universal
Speaker 2: set of units, one at least other science minded aliens
Speaker 2: might understand.
Speaker 1: Right, And that doesn't depend on the conditions of the hydrogen.
Speaker 1: Like if you hot hydrogen and cold hydrogen, they all
Speaker 1: have the same timing.
Speaker 2: This is foreign electron in the lowest state. But you
Speaker 2: know that's pretty common, and we think anybody who studies
Speaker 2: hydrogen is going to understand this transition. It's pretty well known.
Speaker 2: But you know, there are a lot of assumptions there,
Speaker 2: like that the aliens are doing science, that they understand
Speaker 2: we're talking about hydrogen, that they think about time the
Speaker 2: same way we do. There's a lot of things built
Speaker 2: into that, right, right.
Speaker 1: But I think you're saying that like units is maybe
Speaker 1: not the biggest of our problems in communicating with aliens.
Speaker 2: Yeah, you could even get rid of units, and you
Speaker 2: could say, look, are there numbers in the universe that
Speaker 2: don't have units? And there are absolutely, Like in our
Speaker 2: theories of physics, there are numbers that define the theory
Speaker 2: that if you change those numbers, you get a different
Speaker 2: description in the universe. And those numbers don't have any
Speaker 2: units to them. Is pure numbers, and so if you
Speaker 2: wanted to communicate to aliens that were also doing physics
Speaker 2: the way we were, then you might want to communicate
Speaker 2: those numbers. And an example is like the cosmological constant,
Speaker 2: which we think is what's controlling the expansion of the universe.
Speaker 2: That's a number we can measure it. It doesn't have
Speaker 2: any units.
Speaker 1: It doesn't have any units because it's like a ratio
Speaker 1: of something, right.
Speaker 2: Like any number that doesn't have units, you can calculate
Speaker 2: them from ratios. But most naturally they're just numbers, you know.
Speaker 2: Like other examples of things are like the coupling of
Speaker 2: particles to other particles. These are just numbers that go
Speaker 2: in our quantum field theory. They don't have units to them.
Speaker 2: Like every particle that gets mass from the Higgs, there's
Speaker 2: a number associated with that particle, and it controls how
Speaker 2: much mass that particle gets. That's just a number, like
Speaker 2: the top quark has a number, the bottom pork is
Speaker 2: a number, the electron has a number. It's just a
Speaker 2: pure number with no units whatsoever.
Speaker 1: Is it kind of like pi, which is, you know,
Speaker 1: like a feature of geometry.
Speaker 5: Hmm.
Speaker 2: That's another an example. You could use the number of
Speaker 2: spatial dimensions. That's a pure number that describes our understanding
Speaker 2: of the geometry of the universe. Pie is another great
Speaker 2: one because pie is a ratio that works in flat space,
Speaker 2: Like if you live in curve space, the ratio between
Speaker 2: the radius and the circumference of a circle actually isn't pie.
Speaker 2: So there are these numbers that are special that are
Speaker 2: important to the understanding of the universe that don't have
Speaker 2: any units at all. You could try to communicate those.
Speaker 2: But even still, as you were saying, you have a problem,
Speaker 2: like how do you communicate numbers to a bunch of aliens.
Speaker 1: Well, I would imagine maybe you like use one finger
Speaker 1: for one, Like if there are aliens living in the universe,
Speaker 1: they are probably familiar with the concept of a unit, right,
Speaker 1: like one, two, three, And then you build up a
Speaker 1: number system from that, right.
Speaker 2: I think Abby was not talking about aliens that have
Speaker 2: arrived here on Earth that we're interacting with, and you
Speaker 2: can point two apples and say one apple, two apples,
Speaker 2: three apples, But communicating with extraterrestrials like broadcasting a message
Speaker 2: the way that we have done in the way that
Speaker 2: like the pie Ineer plaque, is like, how do you
Speaker 2: build this in and end it out to the universe
Speaker 2: so you can be understood without us, so that somebody
Speaker 2: out there getting that message, you'd be like, oh, look,
Speaker 2: there's smart people over there.
Speaker 1: Mmm, Like how do you basically communicate in mores quote
Speaker 1: kind of yeah?
Speaker 2: How do you encode a signal? So if you're sending
Speaker 2: radio waves to the universe, how do you modulate the
Speaker 2: frequency or the pulses or whatever to send a message
Speaker 2: that indicates, Look, we're smart physics people over here. They
Speaker 2: don't know how to name anything, but we are making
Speaker 2: some progress and understanding the universe.
Speaker 1: Wasn't that in the movie Contact Too? I feel like
Speaker 1: we're referencing this movie a lot, But wasn't that part
Speaker 1: of the signal we got from aliens? Like there was
Speaker 1: a certain number of pulses and the number of pulses
Speaker 1: followed the digits of pie or something like that.
Speaker 2: Yeah. Absolutely, And you're touching on the core issue, which
Speaker 2: is in the end, any message you send is symbols
Speaker 2: like pulses or digits or wiggles or whatever. They only
Speaker 2: represent the pure idea. There's a connection between the idea
Speaker 2: in your head and the idea in these symbols. But
Speaker 2: the symbols themselves are actually kind of arbitrar You come
Speaker 2: up with lots of different ways to enclode the same
Speaker 2: idea in order to decode it, to look at the
Speaker 2: symbols and have the idea in your mind, you need
Speaker 2: to have some commonality. You need to have some frame
Speaker 2: of reference to say, oh, maybe this is how they're
Speaker 2: doing it. Which is why it's so challenging to look
Speaker 2: at the sky and understand whether there are signals from aliens,
Speaker 2: because there's so many different ways they could encode it
Speaker 2: or represent it. We might just be totally missing it.
Speaker 1: Well, I feel like all these questions has maybe two
Speaker 1: dimensions to it, Like one is, how do we just
Speaker 1: demonstrate that we're smart and that we know stuff about
Speaker 1: the universe? And the other one is like how do
Speaker 1: you actually have a conversation about physics with an alien?
Speaker 1: Like if you just wanted to demonstrate, like, hey, we
Speaker 1: know math and we know things about the universe, Like
Speaker 1: you could just send the digits of pie as pulses,
Speaker 1: and somebody would have to interpret that as saying, wait,
Speaker 1: this is not a random sequence of pulses. This is
Speaker 1: a secreence of pulses that followed the digits of pie.
Speaker 2: But you'd also have to figure out how to encode digits,
Speaker 2: like how do you represent different digits in terms of pulses?
Speaker 2: That right, there is an encoding scheme, and that's going
Speaker 2: to be cultural, that's going to be symbolic, that's going
Speaker 2: to be fundamentally arbitrary. So you have to do it
Speaker 2: in a way that you think they could reverse engineer.
Speaker 1: Oh, I see what we're say, Because you're saying, like
Speaker 1: the digits of Pi assumes a base of ten, maybe
Speaker 1: the aliens are doing base of fifty.
Speaker 2: Yeah, so how do you send the number four? Right?
Speaker 2: You break it down into binary? All right, but you
Speaker 2: know you're assuming that they understand that they know what
Speaker 2: it won is in a zero and all this stuff.
Speaker 1: Well, if you send four pulses. Wouldn't that be four
Speaker 1: in any number system.
Speaker 2: Yeah, if you're counting the pulses and that's the way
Speaker 2: you're representing it. You're talking about like a unary number system,
Speaker 2: you know, where you just have like one digit, and
Speaker 2: that's cool. But then they have to know to interpret
Speaker 2: your message that way that it doesn't mean something totally different. Right.
Speaker 2: If you know that what system somebody is using, it's
Speaker 2: not so hard to decode their message. But if you
Speaker 2: have no idea, then you don't know. We actually talked
Speaker 2: to a philosopher on the podcast like a year ago
Speaker 2: who argue that it's probably impossible without any cultural context
Speaker 2: to know for sure what aliens are saying. You might
Speaker 2: get a message and decode it and you don't have
Speaker 2: no idea what they're trying to say, So you have
Speaker 2: no idea whether you've done it right. You could be
Speaker 2: lucky and be like, oh my gosh, I'm guessing this
Speaker 2: encoding and it turns out to give me all the
Speaker 2: digits of pie that must be right. That would be
Speaker 2: a cool experience. You essentially have to randomly guess how
Speaker 2: they're encoding their message, or in reverse, they would have
Speaker 2: to guess.
Speaker 1: How Yeah, because I guess even three, one, four, one, five, whatever,
Speaker 1: the digits of pie, that's only those numbers. If you're
Speaker 1: using the same base ten system that we do, right,
Speaker 1: Like PI in binary is totally different. Yeah, exactly, all right,
Speaker 1: So then what's the answer for albi? It's hopeless, forget
Speaker 1: about it.
Speaker 2: The answer is that it's not hopeless if we have
Speaker 2: a lot in common with the aliens. I mean, if
Speaker 2: there are human like aliens doing human like science and
Speaker 2: a human like way, then we can just send them
Speaker 2: a text basically and they'll get it and understand it.
Speaker 1: They'd be like, who is number?
Speaker 2: Yeah. The more we have in common with them, the
Speaker 2: easier it is for them to understand us and for
Speaker 2: us to understand them. The real question is how much
Speaker 2: in common do we have with them. The most interesting
Speaker 2: aliens are the ones that have the least in common
Speaker 2: with us, that have like evolved in some weird situation
Speaker 2: or doing science in some totally different way using not
Speaker 2: even using mathematics or something. Those would be the ones
Speaker 2: we could learn the most from about the universe. But
Speaker 2: those would also probably be the ones it's hardest to
Speaker 2: make contact with because they have different fundamental assumptions about
Speaker 2: how to communicate and what encoding systems work and whether
Speaker 2: they even use language.
Speaker 1: You know, well, I mean that's sort of maybe according
Speaker 1: to you. Maybe somebody else might argue that those are
Speaker 1: the least useful aliens to talk to, Like, maybe the
Speaker 1: more useful aliens to talk to might be the ones
Speaker 1: that we do have things in common with.
Speaker 2: Yeah, the ones that we have the most in common
Speaker 2: with will definitely have fun stuff to talk about. That
Speaker 2: philosophy we talk to about that scenario said, you have
Speaker 2: to be careful though, because almost anything you say could
Speaker 2: be interpreted as a Russian and the aliens could launch
Speaker 2: a first strike. So the best thing to do in
Speaker 2: that scenario is not to talk to aliens.
Speaker 1: Oh boy, I feel like now you're getting into like
Speaker 1: cosmic paranoia and the whole like, you know, the three
Speaker 1: body problem of creatures in the forest scenario.
Speaker 2: Yeah, it's a real concern, which.
Speaker 1: Sounds like a whole different thing. Yeah, which maybe goes
Speaker 1: outside of Albe's questions.
Speaker 2: That's true. Yeah, maybe OBVI is not being responsible and
Speaker 2: just thinking I'm going to broadcast messages to aliens and
Speaker 2: I don't care if they want to kill us or not.
Speaker 2: But in that scenario where you don't worry about deathly aliens,
Speaker 2: then you should try lots of different schemes. You should
Speaker 2: talk to people from different cultures and have different ways
Speaker 2: of encoding it and representing it, hoping that one of
Speaker 2: them will overlap with the aliens. I think the best
Speaker 2: shot is to use numbers without units, because those are
Speaker 2: the ones that are the most universal, we think.
Speaker 1: At least, like we talked about it, Even if they
Speaker 1: don't have units, you don't know if they're you're using
Speaker 1: the same base numbers, right.
Speaker 2: Yeah, no, absolutely, there's always going to be a challenge
Speaker 2: there for how you represent those numbers in your message.
Speaker 2: But if they think similarly to us, maybe they'll unpuzzle it.
Speaker 2: You know, if there are smart enough aliens out there
Speaker 2: in might figure out how to crack the human code.
Speaker 1: Well, I guess I wonder if you could make an
Speaker 1: argument for like digital being maybe the one with the
Speaker 1: biggest shot at being universal. Like here on Earth we
Speaker 1: had base ten other bases, but ultimately we had to
Speaker 1: build computers. We built them out of binary Those are
Speaker 1: sort of.
Speaker 2: Most natural for us because they represent the states of
Speaker 2: the electronics on which our computers are built. Yeah, aliens
Speaker 2: could have like quantum computers as their first computing right,
Speaker 2: you never know, in which case binary doesn't really make sense.
Speaker 1: All right, Well, I guess then the answer for Auby
Speaker 1: is there isn't maybe a good way to do this
Speaker 1: to broadcast our intelligence, But that maybe doesn't mean that
Speaker 1: we shouldn't do it, right.
Speaker 2: Yeah, absolutely, we can broadcast things in a way that
Speaker 2: makes sense to us and hope that somebody out there
Speaker 2: gets it and here's our message and knows that we
Speaker 2: were for at least a little while here wondering about
Speaker 2: the universe and surviving Boba.
Speaker 1: Is that we could be like, we'll just speak English,
Speaker 1: let everyone else figure it out.
Speaker 2: It's very American, that's basically the approach. Yeah.
Speaker 1: All right, Well, thanks Aby for asking that question, and
Speaker 1: thanks to all of our question askers here today. I
Speaker 1: guess there's no end to human curiosity, for.
Speaker 2: Which we are eternally grateful. So if you are a
Speaker 2: curious person with questions about the universe, don't be shy
Speaker 2: and write them to us to questions at Daniel Andhorgey
Speaker 2: dot com.
Speaker 1: All right, we hope you enjoyed that. Thanks for joining us.
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