Speaker 1: Hey, Daniel, I got a tough question for you. Oh goody,
Speaker 1: that's what I live for. All right. Well you might
Speaker 1: regret that, but here it is. Is physics real or pretend? Boom?
Speaker 1: Oh my gosh. Wow. I don't even know how to
Speaker 1: begin to answer that. What you don't have an answer?
Speaker 1: You mean it could all just be made up? Well,
Speaker 1: you know, physics tries to describe the universe, but it
Speaker 1: might all just be like a convenient mathematical story in
Speaker 1: our head. Yes, math is pretty convenient, I think. I
Speaker 1: guess my next question is then our physicists real or
Speaker 1: are you also made up? I'm not sure. I mean,
Speaker 1: I'm definitely making it up as I go. Well, at
Speaker 1: least you're keeping it real or pretending to Yah, hi
Speaker 1: am or Hey, I'm a cartoonist and the co author
Speaker 1: of Frequently Ask Questions about the Universe. Hi, I'm Daniel.
Speaker 1: I'm a particle physicist and a professor at U c Irvine,
Speaker 1: or at least I pretend to be. Do you have
Speaker 1: to dress up also like Halloween? Do you have a
Speaker 1: professor costume you put on every morning? Yeah? I'm wearing
Speaker 1: my professor costume right now. Sure, jeans and sandals right right.
Speaker 1: I guess socks are not part of the costume. Ever. No,
Speaker 1: I believe strongly in the toe liberation movement. Toes should
Speaker 1: be able to breathe. You're a big t LM fan activist.
Speaker 1: I'm m sure how we got started talking about my
Speaker 1: toes already on the podcast. Well, to stands for a
Speaker 1: theory of everything, right exactly, And you want to let
Speaker 1: your theories breathe. Hopefully that's so they don't smell, you know,
Speaker 1: if nobody wants a stinky theory, Hey, I'll take any
Speaker 1: working theory. I don't care what it smells like. Oh really,
Speaker 1: you might regret saying that. Also, Welcome to the stinky
Speaker 1: cheese theory of the universe. We are pretty cheesy, Daniel,
Speaker 1: But anyways, Welcome to our podcast, Daniel and Jorge Explain
Speaker 1: the Universe, a production of I Heart Radio in which
Speaker 1: we explore the real universe that may actually be out there.
Speaker 1: All those crazy quantum particles frothing and bubbling and waving
Speaker 1: and interfering and weaving together to make an incredible experience
Speaker 1: for me and for you, one chock full of bizarre
Speaker 1: effects and strange mysteries. Mysteries that we hope to be
Speaker 1: able to unravel with the little brain made up of
Speaker 1: its own quantum particles, the universe trying to understand itself.
Speaker 1: And here we are, a tiny little part of the
Speaker 1: universe trying to explain the rest of it to you. Yeah,
Speaker 1: it is a mystery is universe. It's huge, It's full
Speaker 1: of incredible and sometimes unbelievable things where you go, what
Speaker 1: is that for real? Or is that just made up
Speaker 1: by physicists and physics is just sort of like a
Speaker 1: never ending stream of moments like that where we're like,
Speaker 1: how could that be possible? How could it be that
Speaker 1: the universe is actually this way? Think about when people
Speaker 1: discovered the Wow, the universe might be describable by physical laws,
Speaker 1: maybe it's all like clockwork, like deterministic. That must have
Speaker 1: been an incredible moment to feel like our brains could
Speaker 1: describe the universe in a way that predicts its future.
Speaker 1: And then the rug was pulled out from under that
Speaker 1: big idea when we discovered the universe maybe not predictable,
Speaker 1: maybe not deterministic, and even crazier more bonkers realization. It
Speaker 1: kind of says to me, Daniel, like this is keep
Speaker 1: getting it wrong, Like if you got it right the
Speaker 1: first time, you don't need to have your mind blown
Speaker 1: so many times, but just keep a striking out. It
Speaker 1: seems physically is definitely wrong. The goal is to make
Speaker 1: it less and less wrong over time, right, is to
Speaker 1: make it writer and writer as we go. We hope
Speaker 1: to be asymptotically approaching the truth. But you know, we
Speaker 1: may never get there. We may never find a theory
Speaker 1: that we say, this is it. It works, it's satisfying,
Speaker 1: it's simple, We're done. Sounds like a great model for
Speaker 1: your department. Just trying to get it less wrong. I
Speaker 1: think that's a pretty good goal, right, to be the
Speaker 1: least wrong. We're trying to be humble also, right there.
Speaker 1: Some humility is important in academia, right right, because it's
Speaker 1: so rare, right, but like it never happens, it's pretend well.
Speaker 1: It's one of my favorite qualities actually, in my collaborators.
Speaker 1: I work with some of the smartest people on the planet,
Speaker 1: but the ones who are most fun to work with
Speaker 1: all the ones that still have some humility, that know
Speaker 1: that anybody can make mistakes. Nice, and it is an
Speaker 1: interesting universe in which to guess how it might all
Speaker 1: be working and the way we do that is by
Speaker 1: asking questions about the universe. We wonder how it all works,
Speaker 1: why things are the way they are, and how did
Speaker 1: it all come to be. Yeah. An important part of
Speaker 1: figuring out how the universe works is asking why is
Speaker 1: it this way and not some other way? Why does
Speaker 1: the universe follow this law? Why doesn't it follow this
Speaker 1: other law which would seem to make much more sense
Speaker 1: to us. It's a deep part of being human to
Speaker 1: ask these questions about the universe, to try to understand
Speaker 1: what the rules are and what our place is in
Speaker 1: those rules. Yeah, because we are all part of the universe,
Speaker 1: and as humans we seem to be born I asked,
Speaker 1: But the question asking gene do you think it's embedded
Speaker 1: in our genetic instructions? Daniel, This sort of propensity, this
Speaker 1: tendency to ask questions about the universe, about the things
Speaker 1: around this, I don't know. It makes me wonder about
Speaker 1: the nature of intelligence and whether asking questions and curiosity
Speaker 1: is all tied up with intelligence, whether it's an evolutionary trait,
Speaker 1: you know, whether curiosity didn't kill the cat. It fed
Speaker 1: the cat because the cat was wondering, like, is that
Speaker 1: thing tasty? And crunched on it. And sometimes the answer
Speaker 1: is yes, maybe it killed the curious cats, but then
Speaker 1: it's saved like the curious monkeys. You know, maybe it's
Speaker 1: a double edged sword. Curiosity save some species, but uh,
Speaker 1: it's some of them that didn't quite make it right
Speaker 1: because we don't have intelligent cats running around. Cats are
Speaker 1: pretty intelligent, you know, not as intelligent as dogs, but
Speaker 1: you can definitely identify curiosity in other species, right. You
Speaker 1: can tell when your dog is curious about something, or
Speaker 1: even a rat can sniffing around trying to understand what
Speaker 1: something is. Of course, we'll never know what it's like
Speaker 1: to be a rat or a cat or a bat,
Speaker 1: just like we'll never know what it's to be another person,
Speaker 1: but it does feel like being curious is part of
Speaker 1: being alive. We might not be able to answer that
Speaker 1: question until we meet aliens and discover whether or not
Speaker 1: they are also curious about the universe, right, and whether
Speaker 1: they have alien cats who who don't ask questions? And also, Daniel,
Speaker 1: did you just say cats are dumber than dogs? Cats
Speaker 1: definitely dumber than dogs. Absolutely, that's lost half of our
Speaker 1: audience right now. Cat lowers are are pretty fierce. I
Speaker 1: love cats. Cats are wonderful, they're great pets. Let me
Speaker 1: ask you this, Can cats learn? Can cats be trained?
Speaker 1: Pretty sure that you can, right, It's certainly possible to
Speaker 1: teach your cats stuff. I think dogs definitely show a
Speaker 1: larger capacity for learning, so I think they're more intelligent.
Speaker 1: I'm not expert in this stuff, so if you feel
Speaker 1: strongly about cats being intelligent, please write to Jorge and
Speaker 1: tell him all about it. Yes, my email is Daniel
Speaker 1: at Daniel and horrhe dot com. And well, regardless of
Speaker 1: whether cats are smarter or dumber than dogs, humans definitely
Speaker 1: are pretty smart. And we've been asking questions about the
Speaker 1: universe since we were cave men and women and cave children.
Speaker 1: Because we have questions about the universe, right, it's sort
Speaker 1: of a fascinating thing that we all wonder about. How
Speaker 1: does it all work? Yeah, And that's all that science is.
Speaker 1: It's just a bunch of folks asking questions. It's people
Speaker 1: for whom the questions were the most important thing in life.
Speaker 1: And every little piece of science that comes out every
Speaker 1: time you read a news article about like the life
Speaker 1: cycle of newts, or how plants grow, or why rocks
Speaker 1: look a certain color, that's because one person decided that
Speaker 1: was the most important question in the universe when they
Speaker 1: had to devote years of their life to understanding. Though,
Speaker 1: these questions really do drive knowledge forward, and it sounds
Speaker 1: like somebody needs to read that article Are Cats Smarter
Speaker 1: than Dogs? Sounds like great clickbait. But it's not just
Speaker 1: scientists that ask questions. It's everyday people, people like you.
Speaker 1: They are listening to this podcast, and sometimes our listeners
Speaker 1: send us their questions and sometimes we even answer it
Speaker 1: on the podcast. That's right. We want to hear about
Speaker 1: your questions about the universe. Maybe something we said on
Speaker 1: the podcast that you didn't understand, or follow up question
Speaker 1: to something we discuss, or something you read about in
Speaker 1: the news, or just something you've been thinking about as
Speaker 1: you stare up at the night sky. You have questions
Speaker 1: about the universe, we have answers. Please write to us
Speaker 1: two questions at Daniel and Jorge dot com. We answer
Speaker 1: every message and we will answer yours. So today on
Speaker 1: the podcast, we'll be tackling listener questions Number twenty nine.
Speaker 1: Is it real or pretend edition? Is that the real
Speaker 1: title or is that just the pretend title. Well, if
Speaker 1: you're a cat. Then that's the real title of your dog.
Speaker 1: Then you know, you can make up whatever you're like.
Speaker 1: Oh now you're giving dogs extra rights. Oh man, you're
Speaker 1: you're a real catterpressor here. You know. I used to
Speaker 1: be a cat person because we had cats for many,
Speaker 1: many years. Then I had kids and my kids are
Speaker 1: allergic to cats, and the kids wanted to get a dog.
Speaker 1: Now I find myself a dog person, so still love cats,
Speaker 1: but presently have a dog in the family. I see,
Speaker 1: you have to pick a side, you know, your kids
Speaker 1: or cats. You chose their kids. I think that was
Speaker 1: the right choice. I mean, also in parenting. I'm just
Speaker 1: trying to get it less and less wrong every year. Yeah, yeah,
Speaker 1: am high. But we do have some awesome questions here today.
Speaker 1: And there does seem to be a sort of theme
Speaker 1: about things being real or pretend. There's a lot of
Speaker 1: sort of if scenarios here, like what happens if this happens,
Speaker 1: And that's an important part of doing science, you know,
Speaker 1: considering hypotheticals, testing your ideas by considering what might happen
Speaker 1: in this scenario, what might happen in that scenario. It's
Speaker 1: a great way to do physics. You know, somebody tells
Speaker 1: you about how something works, don't just digest it and
Speaker 1: think about the consequences. What about this scenario, How does
Speaker 1: that fit with this other idea? I learned that's the
Speaker 1: way you can weave all these ideas together into a
Speaker 1: complete and holistic understanding of the universe, which, of course
Speaker 1: is the goal of physics. Yeah, because that's kind of
Speaker 1: what science is. Right. It's like you never stop asking questions.
Speaker 1: Even if you find an answer, you can get a
Speaker 1: look for the other question. It's a very annoying habbit. Yeah,
Speaker 1: but it means you always have something to do. And
Speaker 1: even if you think you understand something in one circumstance,
Speaker 1: like you think you know what your dog will do
Speaker 1: if you feed it a treat, you might wonder what
Speaker 1: will my dog do if the treat is inside a
Speaker 1: box where he can't smell it, but he can see
Speaker 1: the treat. These questions help you understand more deeply what's
Speaker 1: going on inside your dog's head. Yeah, I guess are
Speaker 1: you saying dogs or physicists also? Or physicist dogs? Where
Speaker 1: is this analogy going? Launching a whole new podcast called
Speaker 1: The Physics of Dogs. Oh man, you give me the
Speaker 1: dog physicist coming to the Discovery Channel next season, We're
Speaker 1: going to take a bite out of black holes, give
Speaker 1: me a real treat. All right, Well, we have some
Speaker 1: awesome questions through today, some of them about aliens, some
Speaker 1: of them about black holes going too fast, and also
Speaker 1: some about giant space collisions that are maybe mind blowing
Speaker 1: or hard to imagine. So our first question comes from Avanni,
Speaker 1: who is six years old. Hello, my name's Avanni. Anni
Speaker 1: said to my question is a re a ling lot Bretton.
Speaker 1: All right, Sorry if Annie I said you were six,
Speaker 1: but you're nearly six, which is even more impressive than
Speaker 1: you're asking these questions. It's a great question. I love
Speaker 1: this question, such a basic question but also such a
Speaker 1: deep philosophical question. Yeah, Annie wants to know our aliens
Speaker 1: real or pretend? Boy, I feel like we could have
Speaker 1: a whole podcast series just on that question. You know,
Speaker 1: there's so many wrinkles. They're like, is anything real? Is
Speaker 1: it all just pretend? What does it mean to pretend?
Speaker 1: What does it mean to be an alien? You can
Speaker 1: go down a real rabbit hole here. Yeah. A big
Speaker 1: part of doing physics is coming up with pretend scenarios
Speaker 1: and asking like, well, could that be real? How do
Speaker 1: we know? Often before we see things out there, we
Speaker 1: do come up with the idea for what might be
Speaker 1: out there. So, you know, before the Higgs particle was observed,
Speaker 1: was it real or was it pretended? Was just an
Speaker 1: idea in our minds until we found it? And have
Speaker 1: you figured that out yet? We pretend to. Yeah, absolutely,
Speaker 1: But you know, actually, my daughter, I think when she
Speaker 1: was around five or six, she asked me this almost
Speaker 1: the same question, like the aliens were real or not?
Speaker 1: I guess when you're that age, you get a lot
Speaker 1: of like stories about aliens or movies about aliens or
Speaker 1: shows about aliens, and you're like, and you're probably in
Speaker 1: your little brain you're thinking, is this for real? Or
Speaker 1: is this just like you know, dragons and unicorns? Yeah?
Speaker 1: I think it comes from seeing fictionalized portrayals of stuff.
Speaker 1: But you know, you might ask, like, well, why are
Speaker 1: aliens in fiction? Why do we tell stories about aliens?
Speaker 1: Why are they in the movies? Why are they on
Speaker 1: the brains? Right? They're on the brains because we wonder
Speaker 1: if they are real, because we think about them as
Speaker 1: a way to explore this question of are we alone
Speaker 1: in the universe? Right, So it's an important part of
Speaker 1: doing science is coming up with these pretend scenarios. Oh boy,
Speaker 1: I thought you were going to say it's because they're real,
Speaker 1: Like if there's some kind of conspiracy going on here,
Speaker 1: I want them to be real obviously, Like I would
Speaker 1: love to talk to aliens about physics and learn all
Speaker 1: sorts of things about how to look at the universe
Speaker 1: from a different perspective. But of course we don't know
Speaker 1: if they're real. I guess is that the basic answer
Speaker 1: that you would give a body is that we don't
Speaker 1: know if aliens are real or pretend. Yeah, we don't
Speaker 1: know currently they are just pretend. But why do we pretend?
Speaker 1: We pretend because we hope that they are real, and
Speaker 1: to discover them, we need to pretend that they are real.
Speaker 1: We need to think about what they might be like
Speaker 1: in order to know how to look for them. We
Speaker 1: need to imagine different scenarios for how they might communicate,
Speaker 1: how they might live, how they might think, so that
Speaker 1: we are prepared to discover them, so we know where
Speaker 1: to look and how to look for them. Yeah, so
Speaker 1: that I guess, or pretend, Like the things you see
Speaker 1: on TV right now, everything you see about aliens is
Speaker 1: pretend somebody just made that up, but we actually don't
Speaker 1: know if they are real or not, meaning that they
Speaker 1: could be real. Yeah, they could be real. Aliens are
Speaker 1: pretend the same way string theory is pretend like it's
Speaker 1: a hypothetical, it's a possible scenario. We don't know if
Speaker 1: it describes our actual universe. We play around with it
Speaker 1: to see like does this make sense? Could it be real?
Speaker 1: Sort of two steps in the question, they're right, like
Speaker 1: could this be real? Is it allowed by the laws
Speaker 1: of the universe as it explained the kind of things
Speaker 1: we see, So we can ask questions like how could
Speaker 1: else could you make life? And could life evolve in
Speaker 1: other places in the universe? Is that consistent with our understanding?
Speaker 1: And then, of course there's the second, totally severate question,
Speaker 1: which is are they actually real. We might live in
Speaker 1: the universe where aliens are possible but don't exist. Could
Speaker 1: be that the universe allows for life to start at
Speaker 1: other places, but that it just didn't. Well maybe for
Speaker 1: somebody like Vanni. You can step us through, like why
Speaker 1: do we think that aliens could be real? We've only
Speaker 1: been to one planet Earth with life in it. What
Speaker 1: makes us think that there could be other planets with
Speaker 1: aliens in them. It's a great question, and I think
Speaker 1: an important thing to remember is that something we've been
Speaker 1: learning over the last few hundred years is that where
Speaker 1: we are in the universe doesn't seem to be very special.
Speaker 1: Like we're just in one little spot in one galaxy,
Speaker 1: among billions and billions, maybe trillions, maybe an infinite number
Speaker 1: of galaxies. So there's a huge wage universe out there,
Speaker 1: and nothing about where we are seems to be very
Speaker 1: special so far, Like the kind of star we have
Speaker 1: is not that unusual star, and there's billions of stars.
Speaker 1: The kind of planet we have, we've recently discovered that
Speaker 1: there are lots of these kinds of planets, planets made
Speaker 1: out of rock, not too far and not too close
Speaker 1: to the Sun. That water is everywhere in the universe.
Speaker 1: It's not too complicated, and so we can imagine ways
Speaker 1: for life to have started on other planets. In fact,
Speaker 1: it seems like there may have been many, many opportunities
Speaker 1: for this to happen. We don't think that the chemicals
Speaker 1: that we find here on Earth are unique or special,
Speaker 1: and so it's not that hard to imagine life starting
Speaker 1: in other places or maybe even many many other places
Speaker 1: in the universe, right, I think the ideas that there
Speaker 1: are a lot of planets out there, and a lot
Speaker 1: of planets out there are sort of like the Earth.
Speaker 1: They sort of maybe even look a lot like the
Speaker 1: Earth with water and like a nice atmosphere, nice clouds
Speaker 1: in the sky. And so those are the kinds of
Speaker 1: planets that least what we know about of life. There
Speaker 1: could be other living things in those planets. There could be,
Speaker 1: and here we're just talking about life as we know it.
Speaker 1: You conditions similar to Earth that might make life in
Speaker 1: a way that's similar on Earth. And you know, an
Speaker 1: important part to pretend though, is thinking about different aliens.
Speaker 1: Rarely in movies do you see aliens looking exactly like humans,
Speaker 1: Because we think that probably some aspects of life here
Speaker 1: on Earth are basically random, that just evolution happened to
Speaker 1: follow this path, and it could have followed another path.
Speaker 1: We don't really know, like what are the spectrum of
Speaker 1: possible options. What else could have evolved and have been intelligent.
Speaker 1: It's hard to think outside of this box because we're
Speaker 1: just so used to life on Earth, and it's possible
Speaker 1: that life on other planets looks a little bit different
Speaker 1: from life on our planet, or could be fundamentally radically
Speaker 1: mind blowing lee different in ways that are hard for
Speaker 1: us to even imagine. Right, But I guess even though
Speaker 1: there are a lot of planets out there, and a
Speaker 1: lot of them that looked like the Earth, we sort
Speaker 1: of don't know if what makes you know living things
Speaker 1: happened in a planet like that is special or whether
Speaker 1: that's common too, Like there might be a Brazilian planet
Speaker 1: like the Earth out there, but maybe like our planet
Speaker 1: is the only one where things just happened to come alive.
Speaker 1: That's a possibility, right, That's definitely a possibility because there's
Speaker 1: a gap in our understanding. I said earlier that we
Speaker 1: think the chemistry of Earth is probably not unique. But
Speaker 1: what we don't understand is how you get from the
Speaker 1: chemistry of Earth to life on Earth. How do you
Speaker 1: go from a primordial soup of like building blocks of
Speaker 1: life to actual life, self reproducing objects that can build complexity.
Speaker 1: We do not understand that step, like we don't understand
Speaker 1: how it happened here precisely, which means that we can't
Speaker 1: say how likely it is to happen somewhere else, and
Speaker 1: our ignorant ranges from like, oh, it can be pretty common.
Speaker 1: You get it like half the time. If you have
Speaker 1: a primordial soup and it sits around for a few
Speaker 1: million years slashing on alien shores, that fifty percent of
Speaker 1: the time you get life. You know. Arguments in favor
Speaker 1: of that are that it didn't take that long on
Speaker 1: Earth for life to start. We think, you know, less
Speaker 1: than a billion years after the Earth began. We think
Speaker 1: there might have been like a little micro On the
Speaker 1: other hand, it could be super duper rare. It could
Speaker 1: be that it takes trillions and trillions of planets for
Speaker 1: it to happen. One time. We could be the only
Speaker 1: life in the entire universe because it's just so rare.
Speaker 1: We just don't understand the mechanism for that. So we
Speaker 1: don't have any idea how rare or how common that
Speaker 1: crucial step is. Right, And I guess if I'm a
Speaker 1: six year old or nearly six year old like Evanni,
Speaker 1: I might be wondering right now, like how can we
Speaker 1: not know if there are aliens out there? Like can't
Speaker 1: we just look at them or good to them or
Speaker 1: see them from Earth? Yeah, we do know something, right,
Speaker 1: if there were aliens everywhere. If there were aliens on
Speaker 1: Mars and on Venus and building civilizations around Jupiter, then
Speaker 1: we would have seen them. So we know the universe
Speaker 1: is not like overwhelmed with life. It's not like brimming
Speaker 1: with life. Even if they were like really fancy aliens
Speaker 1: and one star over, we might have seen messages from them.
Speaker 1: We might have heard from them already. So in our
Speaker 1: little vicinity, it seems like, you know, there isn't any
Speaker 1: other life that we have found yet. There are still
Speaker 1: some places in the Solar System we haven't looked, and
Speaker 1: there are lots of ways for alien life to be
Speaker 1: like kind of nearby but not that close, and us
Speaker 1: to not have seen it. But so far our neighborhood
Speaker 1: seems sort of abandoned except for us, right at least
Speaker 1: for now, right Like, it could also be that there
Speaker 1: were aliens here or around a long time ago, but
Speaker 1: they're not anymore. Or it could be that there will
Speaker 1: be aliens in our neighborhood in the future, just not
Speaker 1: right now. Yeah, the universe is a very long trajectory.
Speaker 1: Our life cycles and the whole history of humanity on
Speaker 1: Earth is just a blip in the cosmic history. So
Speaker 1: it might be that aliens lived around a nearby star
Speaker 1: for a billion years and then died out and we
Speaker 1: just missed them. Or they might arise in two billion
Speaker 1: years and last for a trillion years. But we're just
Speaker 1: a little bit too early. There's lots of ways for
Speaker 1: us to not see aliens. All right, Well, then, I
Speaker 1: think the answer for Evanni is that the universe is
Speaker 1: so big that aliens are probably real, but so far
Speaker 1: we just have to pretend that their pretend because we
Speaker 1: haven't seen any or talked to any yet so far,
Speaker 1: and that pretending about aliens is an important way of
Speaker 1: actually discovering them, thinking about what they might be like. Yeah,
Speaker 1: it's part of using your imagination, which is a big
Speaker 1: part of using your curiosity, which is a big part
Speaker 1: of signs. And maybe, Vonnie, you'll grow up and be
Speaker 1: the one to discover aliens. All right, Well, let's get
Speaker 1: it to our other questions here about fast moving black
Speaker 1: holes and also white hole coalitions. But first let's take
Speaker 1: a quick break. All right, we are answering listener questions
Speaker 1: here today, and Daniel, are we for real answering them
Speaker 1: or just pretending to answer them? I'm not sure. I
Speaker 1: know the difference anymore. Your life is a blur. You're
Speaker 1: doing fiction, you're doing physics. What is real? Man? I'm
Speaker 1: really pretending to do my best. All right, Well, we
Speaker 1: have our second question here of the day, and this
Speaker 1: one comes from Jeff, and he's wondering what happens when
Speaker 1: heavy things go really fast? Hi, Daniel and horror. Hey,
Speaker 1: my name is Jeff, and I've got a question for
Speaker 1: you about high energy photons, black holes, and relativity. I've
Speaker 1: heard that if you can get enough energy in a
Speaker 1: small enough volume, a black hole conform. Right, if you
Speaker 1: had a laser that could shoot ultra high energy photons,
Speaker 1: those photons could become black holes. But what would an
Speaker 1: observer are moving close to the speed of light relative
Speaker 1: to that laser c bec as those photons and that
Speaker 1: reference frame would have less energy. They shouldn't observe these
Speaker 1: photons becoming black holes. It sounds kind of paradoxical. I'm
Speaker 1: sure I'm missing a subtle point somewhere. But if you
Speaker 1: could help shine a light on it, that would be appreciated.
Speaker 1: All Right, that is a pretty mind blown question. I'm
Speaker 1: gonna pretend that I understood it, but I think what
Speaker 1: he's asking, Jeff is asking, is that black holes form?
Speaker 1: Because when you have enough energy in one spot, And
Speaker 1: so if you take a little rock and you get
Speaker 1: it going really fast, doesn't it get a lot of
Speaker 1: kinetic energy? And if it has enough kinetic energy, doesn't
Speaker 1: it at some point become a black hole because of
Speaker 1: its kinetic energy. Yes, it's a really good question gen
Speaker 1: about like whether observers in different frames, moving at different
Speaker 1: speeds all see a black hole made at the same time.
Speaker 1: Do they agree about whether something is a black hole
Speaker 1: or not? And it's a great question because energy is relative, right,
Speaker 1: Like if I'm holding a rock, I see it having
Speaker 1: no velocity, so it has no kinetic energy. Whereas if
Speaker 1: you're running by at se the speed of light because
Speaker 1: you're really fast, you measured that rock to have a
Speaker 1: lot of velocity relative to you, and so a lot
Speaker 1: of energy relative to you. So you see that rock
Speaker 1: is having more energy. So in principle, you could say, oh,
Speaker 1: that rock has enough energy to form a black hole,
Speaker 1: and I could say no, it doesn't have enough energy
Speaker 1: to form a black hole. But you know, one of
Speaker 1: us would have to be right, because either it's the
Speaker 1: black hole or it's not right. Because velocity is relative, right,
Speaker 1: it depends on how you measure it. And so does
Speaker 1: that mean then that kinetic energy is also relative, Like
Speaker 1: it doesn't really exist. Kinetic energy is definitely relative. And
Speaker 1: there's an important difference between things being conserved and things
Speaker 1: being invariant, right, Like something's invariant if everybody measures it
Speaker 1: and gets the same answer. Like everybody measures the speed
Speaker 1: of light to be the speed of light, no matter
Speaker 1: what frame you're in, how fast you're going, etcetera. Not
Speaker 1: everybody measures velocity to be the same number. If you're
Speaker 1: moving relative to me, then you have a different measurement
Speaker 1: of my velocity, and so a different measurement of my energy.
Speaker 1: Right now, in your frame, energy is conserved and in
Speaker 1: my frame energy is conserved. But we actually measure different
Speaker 1: amounts of energy. So energy is conserved that is in
Speaker 1: flat space, right, But it's not invariant, So different people
Speaker 1: measure different amounts of energy. Yes, it's relative. So I
Speaker 1: think that's the paradox that Jeff pointed to, is that
Speaker 1: you're they're holding a rock to you. The rock has
Speaker 1: no energy, right, it's just sitting there in your the
Speaker 1: palm of your hand. But for me, that I'm going
Speaker 1: at seventy the speed of light zooming past you. I'm
Speaker 1: seeing you from my point of view. I'm seeing you
Speaker 1: and the rock have a ton of energy, right because
Speaker 1: you have fast and you're moving really fast relative to me.
Speaker 1: So I'm thinking, oh, my goodness, there's so much energy there. Well,
Speaker 1: first of all, I can't believe Daniels wiming fast, but
Speaker 1: there's so much energy there. The black hole should be
Speaker 1: forming there. I mean, it would be a really short moment.
Speaker 1: There would be like, well, oh, aready gone. I wouldn't
Speaker 1: wonder about it too long. It's a really fun question,
Speaker 1: and it gives us an opportunity to understand a little
Speaker 1: bit more about general relativity. The short answer is that, remember,
Speaker 1: a black hole is curvature of space, and that it
Speaker 1: forms when you have enough energy density in a certain location.
Speaker 1: But it's not that simple exactly. It's not just like
Speaker 1: more energy density means more curvature and eventually you hit
Speaker 1: a threshold and you get a black hole. It's more
Speaker 1: complicated than just like a certain amount of energy density.
Speaker 1: It's not just like one number that controls the solution
Speaker 1: to Einstein's equations. Einstein's equations are a big, complicated nightmare,
Speaker 1: and different pieces of it feed in slightly differently. It's
Speaker 1: not just like you measure the energy density. This is
Speaker 1: this thing called the stress energy tensor. And kinetic energy
Speaker 1: feeds in differently from potential energy, which feeds in differently
Speaker 1: from other kinds of energy. So it all sort of
Speaker 1: dances together and to get a solution, Well, I guess
Speaker 1: maybe the basic question is does kinetic energy bend space? Also?
Speaker 1: Like I have a rock moving really fast, is that
Speaker 1: kinetic energy bending the space around the rock as it's moving?
Speaker 1: Or even if I just have a like a photon
Speaker 1: which has sort of momentum, right, kinetic energy, is that
Speaker 1: photon bending space also? It can? Right? It does contribute, right,
Speaker 1: It's not like the universe just ignores kinetic energy. It
Speaker 1: does contribute to the effects on space, right. But it's
Speaker 1: not trivial. It's not like you can just add up
Speaker 1: all the energy and say here you have enough to
Speaker 1: have a black hole. Ein sense equations, remember, are very complicated,
Speaker 1: so it's not easy to say, here's this configuration. Now
Speaker 1: we know exactly what happens. And in fact, it's really
Speaker 1: a nightmare to solve E sense equations For anything with
Speaker 1: kinetic energy. I mean, it's a nightmare to solve it
Speaker 1: in almost any circumstances. We've only ever solved Einsteins equations
Speaker 1: under a few very specific, very simple situations, like a
Speaker 1: huge amount of mass at rest or the universe filled
Speaker 1: comogeneous le wouldn't matter. We haven't even solved different simple
Speaker 1: things like two objects orbiting each other. Right, that's too
Speaker 1: complicated for us to figure out. And so to solve
Speaker 1: these problems, what we typically do is we use a trick.
Speaker 1: We say, well, this problem is too hard to solve.
Speaker 1: We don't know how to solve the problem of I
Speaker 1: have a rock moving past me with a lot of
Speaker 1: kinetic energy. I can't solve that one. But can I
Speaker 1: solve a different problem that I know has the same answer.
Speaker 1: So one thing we know about general relativity is that
Speaker 1: it is invariant. Everybody should agree about what happens. But
Speaker 1: whether there's a black hole, regardless of your coordinates, how
Speaker 1: you choose your reference frame, how you organize spacetime, right
Speaker 1: where you put your axes shouldn't matter. Everybody should agree
Speaker 1: about whether or not there is a black hole. So
Speaker 1: that's a short answer. Jorge and I can't disagree about
Speaker 1: whether the rock forms into a black hole. It's not
Speaker 1: like he could see a form of black hole and
Speaker 1: I don't. We have to agree. We know that the
Speaker 1: equations of general relativity are invariant, so we say, well,
Speaker 1: let's solve the problem in the easier case where I'm
Speaker 1: just holding the rock and I can ask the question,
Speaker 1: doesn't have enough mass to form a black hole? Yes
Speaker 1: or no? And then we say, well, Jorge must see
Speaker 1: the same answer. We don't know how to solve the
Speaker 1: equations for Jorge, but we know what the answer has
Speaker 1: to be, meaning that because you don't see a black
Speaker 1: hole in the ruck in your the palm of your hand,
Speaker 1: then I shouldn't see a black hole when I'm moving
Speaker 1: past you se of the speed of light. You're saying,
Speaker 1: we should all come out with the same observation exactly.
Speaker 1: And if we were better at math and we knew
Speaker 1: how to solve that problem in the case of an
Speaker 1: object moving really really fast, then we would get the
Speaker 1: same answer. We know that that's true because we know
Speaker 1: that general relativity is invariant, that no matter what frame
Speaker 1: you solve it and you do get the same answer.
Speaker 1: We just can't work through the details of that math
Speaker 1: right now, because we don't know how to solve these
Speaker 1: equations in every possible scenario. Though typically we just say, well,
Speaker 1: let's solve it an easier case and then argue that
Speaker 1: the answer must be the same in this other case.
Speaker 1: It sounds like a pretend argument. But I guess is,
Speaker 1: why do you why does it have to be that way?
Speaker 1: You know, like, why couldn't do you see no black hole?
Speaker 1: But to me it looks like you are holding a
Speaker 1: black hole, you know, like it maybe somehow it sort
Speaker 1: of looks like it nothing can escape there. But to you,
Speaker 1: it does seem like something can escape from your the
Speaker 1: palm of your hand. Why couldn't that be true? Well,
Speaker 1: remember what the condition for a black hole is. We're
Speaker 1: talking about an event horizon, talking about our region in
Speaker 1: space where nothing can ever leave. So it would be
Speaker 1: a paradox, right, if you see an event horizon, but
Speaker 1: I don't. Right, that means that I could see a
Speaker 1: photon leave this rock and strike you. But you're saying
Speaker 1: that no photon could ever leave that rock and strike you. Right,
Speaker 1: Those two things are in contradiction with each other. And
Speaker 1: remember that there's lots of relativity. In relativity, right, people
Speaker 1: can disagree about the order of events, for example, but
Speaker 1: you know whether two things strike each other, for example,
Speaker 1: whether that photon reaches Jorge or not are things that
Speaker 1: all observers do have to agree on, all right, So
Speaker 1: then what's kind of the answer here? If we both
Speaker 1: have to see a black hole not forming in the
Speaker 1: palm of your hand, then does that mean that my
Speaker 1: velac city is irrelevant, like kinetic energy doesn't go into
Speaker 1: really the formation of a black hole. Because I feel
Speaker 1: like that's kind of what you're saying, is that me
Speaker 1: moving fast is irrelevant, and therefore it can't affect whether
Speaker 1: or not a black hole forms or not. That's right,
Speaker 1: and that sort of makes sense. You know, if I'm
Speaker 1: sitting here holding a rock and you're running by me
Speaker 1: a mile away, how could you're running by me make
Speaker 1: my rock implode into a black hole? Right? It doesn't
Speaker 1: even make sense. And then whether or not a black
Speaker 1: hole existed would depend on like everybody else's speed in
Speaker 1: the universe. It shouldn't make sense, right, Your intuition tells
Speaker 1: you that it's either a black hole or it's not.
Speaker 1: And no matter how fast where he runs, he can't
Speaker 1: turn my rock into a black hole. Well, I hate
Speaker 1: to run, so that wouldn't happen anyways. I think what
Speaker 1: you're saying is that you know, the formulas that say
Speaker 1: what makes a black hole or what turns into a
Speaker 1: black hole somehow sort of cancel out the effects of
Speaker 1: kinetic energy. Because you said earlier that kinetic energy does
Speaker 1: bend space, so you would think that it would help
Speaker 1: form a black hole, but equations of the black hole
Speaker 1: are such that it actually sort of ignores the kinetic energy. Yeah,
Speaker 1: it all gets woven in a very complicated way that frankly,
Speaker 1: we don't even really understand how to solve in an
Speaker 1: exact way. We have like numerical solutions to this stuff,
Speaker 1: but most of the solutions to general relativity are done
Speaker 1: using these kind of assumptions like that everything is invariant,
Speaker 1: that you get the same answer in every frame, so
Speaker 1: let's find the one where it's easiest. And we do
Speaker 1: this all the time in physics. You want to solve
Speaker 1: a problem where like a ball is rolling down a plane,
Speaker 1: then you choose axis that make that simple. You know
Speaker 1: where your x axis is like aligned along the plane
Speaker 1: rather than with the ground, because it makes the maths simpler.
Speaker 1: So we're always doing this kind of thing where we
Speaker 1: transform the problem to be a simpler one that has
Speaker 1: the same answer. Cool. All right, Well, it sounds like
Speaker 1: you're waving your hands with some math here a little bit.
Speaker 1: But it sounds like the answer is that to answer
Speaker 1: Jeff's question, is that fast moving objects do have extra
Speaker 1: energy because of their kinetic energy, depending on who measures it,
Speaker 1: But that kinetic energy can't affect the formation of whether
Speaker 1: or not it forms a black hole exactly. And Jeff
Speaker 1: actually asked his question in terms of photons, but the
Speaker 1: same kind of principles apply. You know, you have enough
Speaker 1: energy to form the black hole or you don't, and
Speaker 1: it's the same in every frame. Well, we have one
Speaker 1: more question here today, and it's about what happens when
Speaker 1: white holes collide with black holes, and I'm guessing it's
Speaker 1: not just that they form a gray hole. We'll get
Speaker 1: into the real answer here and not to pretend one.
Speaker 1: But first let's take another quick break. All right, we
Speaker 1: were answering listener questions and I feel like I've got
Speaker 1: in my mind blown twice already. First of all, that
Speaker 1: there's a nearly six kid thinking about aliens in the universe.
Speaker 1: That's amazing. That's awesome. And also that black holes don't
Speaker 1: depend on how fast you're moving. Yep, black holes are
Speaker 1: mind blowing and they're really fun hypothetical questions to think
Speaker 1: about to make sure that you want understand how they
Speaker 1: work and what the rules are and how it all
Speaker 1: comes together. It's really useful to think about crazy hypotheticals. Alright, well,
Speaker 1: we have one more question here, and this one comes
Speaker 1: from Carson Hi di Hore. Carson, here, I have a
Speaker 1: question about black holes and white holes. Could you please
Speaker 1: explain what would happen if the two were to quiet?
Speaker 1: And thanks for answering all my questions. Alright, awesome question, Carson.
Speaker 1: That is a great question because I also wonder if
Speaker 1: I thought this myself. Carson's question is what happens if
Speaker 1: I take a black hole and I make it crash
Speaker 1: or collide with a white hole? It is a wonderful question.
Speaker 1: I really love this. When I first got this question,
Speaker 1: I thought, WHOA, I've never even thought about that. How
Speaker 1: have I never considered what might happen in this scenario?
Speaker 1: So I have to go off and think about a
Speaker 1: little bit. And I also reached out to a quantum
Speaker 1: gravity expert who will chime in a little bit later on.
Speaker 1: You can just pretend that you came up with that information.
Speaker 1: I can't pretend to be a quantum gravity expert as
Speaker 1: hard as I try. Well, what happens when a white
Speaker 1: hole collects with a black cool That's a great question,
Speaker 1: and so let's step through this. What is exactly a
Speaker 1: white hole? So a white hole is a really weird
Speaker 1: theoretical object, and it's one of these things where it's
Speaker 1: not even really well to find what it is. There's
Speaker 1: sort of like a few white hole kind of ideas
Speaker 1: out there that all sort of fall in this general category.
Speaker 1: So the answer to the question depends a little bit
Speaker 1: on what a white hole is. And it's sort of
Speaker 1: like three different ideas that might be worth thinking about
Speaker 1: for what a white hole is. I guess, first of all,
Speaker 1: is this a real thing that physicists, a fuel that
Speaker 1: really exists, or is this just like it's possible in
Speaker 1: the equations but we don't really have sort of dug
Speaker 1: into it to get the sense whe whether or not
Speaker 1: it can't exist in the universe. Are you asking me
Speaker 1: if white holes are real or pretend? Yeah, Well, I'm
Speaker 1: asking if the theory is real or pretend. So white
Speaker 1: holes do exist in the theory. We don't know if
Speaker 1: white holes are real in our universe. And as you'll
Speaker 1: hear about, some of the parts of the theory are
Speaker 1: a little bit speculative and a little bit fuzzy, So
Speaker 1: we're not sure whether white holes. Nobody's ever seen a
Speaker 1: white hole, but there are parts of the theory that
Speaker 1: suggests that they might be real. And if that sounds
Speaker 1: pretty speculative, remember that until a few decades ago, black
Speaker 1: holes were in the same category. They're in the kind
Speaker 1: of thing that we're in the theory, and a lot
Speaker 1: of people thought, well, that would never actually happen in reality.
Speaker 1: And now we're pretty sure black holes are real, that
Speaker 1: they are out there. The white holes might be real,
Speaker 1: or they might just be pretended. We're not sure. But
Speaker 1: that's where we are with white holes, is that we're
Speaker 1: like three decades behind black holes, because I feel like
Speaker 1: black holes, we thought they were maybe met real or
Speaker 1: maybe not. Then we sort of saw evidence of their presence,
Speaker 1: and then only until very recently do we have actual
Speaker 1: pictures of them. Were still in the maybe they're not
Speaker 1: real phase, right, we're never with black holes because the
Speaker 1: only way we know they are real is by looking
Speaker 1: at the stuff that's nearby them, and black holes are
Speaker 1: sort of like the only thing that fits that bill
Speaker 1: until recently now we have some like alternative theories or
Speaker 1: like what might be going on inside black holes is
Speaker 1: maybe they're not actually gr black holes. And we'll talk
Speaker 1: about that actually in a minute. But yeah, white holes
Speaker 1: are behind black holes. Black holes we thought of, you know,
Speaker 1: in the early part of the nine hundreds, and then
Speaker 1: discovered indirectly fifty years later. White holes weren't really thought
Speaker 1: about until like the sixties or seventies, when people who
Speaker 1: are understanding the nature of general relativity a little bit
Speaker 1: more deeply. So, yeah, they're bout fifty years behind black holes,
Speaker 1: all right. So you were saying, there are three kinds
Speaker 1: of white hole ideas or possibilities. What are they? So
Speaker 1: the simplest one to think about is the endpoint of
Speaker 1: a wormhole. A wormhole is like a connection between two
Speaker 1: points in space where you can enter in one spot
Speaker 1: and come out somewhere else. And this is possible because
Speaker 1: general relativity tells us not just the space can do
Speaker 1: things like wiggle or bend in the presence of mass.
Speaker 1: It can also be like connected in weird ways. You
Speaker 1: can like stitch it together to say, this point in
Speaker 1: space over here is actually also next to that point
Speaker 1: in space. Meaning instead of just being able to go
Speaker 1: like up, down, left, right, side to side to adjacent points,
Speaker 1: now one of those adjacent points is actually like somewhere
Speaker 1: else in space, but also at the same time adjacent
Speaker 1: to this point in space. So these wormholes can sometimes
Speaker 1: be like a black hole linked to a white hole.
Speaker 1: We fall into the black hole and you get spat
Speaker 1: out the white hole on the other side. It's like
Speaker 1: they almost like the opposite of a black hole. Yes,
Speaker 1: so conceptionally a white hole is the opposite of a
Speaker 1: black hole. Where a black hole has an event horizon
Speaker 1: where nothing can escape, a white hole as an event
Speaker 1: horizon where nothing can enter. It's like you've arrange the
Speaker 1: shape of space in such a way that nothing can
Speaker 1: ever cross that event horizon going in, the way in
Speaker 1: a black hole, nothing can ever cross the event horizon
Speaker 1: going out. Or a white hole, it's like the opposite,
Speaker 1: I guess, meaning like if you shoot a photon at
Speaker 1: a white hole will just bounce back. You will never
Speaker 1: reach the event horizon exactly and maybe turn around and
Speaker 1: come back. Well, the answer to that depends a little
Speaker 1: bit on the form of the white hole that you're
Speaker 1: talking about. In some theories it will fall forever towards
Speaker 1: the event horizon but never actually cross it. All right, Well,
Speaker 1: what's the second kind of white hole? So the second
Speaker 1: kind of white hole sort of like a pure gr
Speaker 1: white hole. It comes from looking at the solutions to
Speaker 1: Einstein's equations. So you have like a big massive stuff,
Speaker 1: so much stuff that you could get a black hole, right,
Speaker 1: that's a solution to the equations. Turns out that general
Speaker 1: relativity has this symmetry in it that every solution to
Speaker 1: general relativity also works backwards in time. General relativity doesn't
Speaker 1: seem to prefer one direction in time. Like the description
Speaker 1: going forward and description going backwards both are solutions to
Speaker 1: Einstein's equation. So what that means is that, like, if
Speaker 1: you have a massive stuff that can give you a
Speaker 1: black hole where nothing can ever escape the event horizon,
Speaker 1: then it also can give you a white hole. And
Speaker 1: like the opposite solution, the time reverse solution of a
Speaker 1: black hole is also a solution to the equations. So
Speaker 1: I put a big blob of stuff in the universe.
Speaker 1: It can give you a black hole where space has
Speaker 1: been so everything falls in a crosses the event horizon
Speaker 1: and never leaves. But it could also give you a
Speaker 1: white hole, the opposite structure of space that nothing can
Speaker 1: ever enter the event horizon. Wait, what it would be
Speaker 1: because you have a lot of stuff. But would it
Speaker 1: be random if it turns into a white hole or
Speaker 1: a black hole like could be like a flip of
Speaker 1: a coin. We don't really understand whether these solutions are physical. Right,
Speaker 1: this is like a solution to the equation, but we
Speaker 1: don't really understand, like does that mean these things can
Speaker 1: actually exist? We've never seen one. It's sort of like
Speaker 1: when you're solving an equation in math and you have
Speaker 1: like an x squared equal to nine, X could be
Speaker 1: three or x could be minus three, right, And sometimes
Speaker 1: that makes sense and sometimes it just doesn't. Right. Sometimes
Speaker 1: that's like a non physical solution, so you just ignore it.
Speaker 1: We don't know if this is like a physical solution
Speaker 1: or a non physical solution. One problem with this time
Speaker 1: reverse scenario is that requires the black hole or the
Speaker 1: white hole to be eternal for it to always be there.
Speaker 1: For the time reversal solution to exist, it has to
Speaker 1: like exist all the way back to negative infinity, otherwise
Speaker 1: the symmetry would be broken. Right, the black hole is
Speaker 1: formed at some moment by a collapsing star, for example,
Speaker 1: that's how many black holes are formed, then the solution
Speaker 1: doesn't work backwards in time anymore. That was required the
Speaker 1: start to like uncollapse somehow. So it's like the opposite
Speaker 1: of a black hole mathematically, but we don't know that
Speaker 1: could be physically possible. We don't know if that could
Speaker 1: be physically possible, and it requires this weird thing called
Speaker 1: an eternal black hole, which we also don't know if
Speaker 1: it's physically possible at all. So it's sort of like,
Speaker 1: you know, it's a theoretical playground. It's like, here's something
Speaker 1: the math does and it has a cool name and
Speaker 1: weird physical effects, but we don't really know if that's
Speaker 1: real or if it could appear in our universe, and
Speaker 1: there's no physical way we know of to create this thing,
Speaker 1: this backwards in time eternal black hole. All right, And
Speaker 1: then there's one last kind of white hole here that
Speaker 1: has to do with quantum physics. Yeah, one issue is
Speaker 1: that we think that general relativity is not complete, right,
Speaker 1: It can't really describe the universe as we know it.
Speaker 1: We don't think that singularities are real. We think that
Speaker 1: the infinity predicted by general relativity is like a failure
Speaker 1: of the theory and that if things get actually that
Speaker 1: compact quantum effects takeover. But we don't have like a
Speaker 1: quantum theory of gravity. We don't know how gravity interacts
Speaker 1: with quantum mechanics. But we did talk on the program
Speaker 1: once about a possibility, possibility that maybe black holes don't
Speaker 1: actually have singularities at their heart. Maybe the curvature of
Speaker 1: space creates time dilation, so like time moves really really slowly,
Speaker 1: and what we're seeing is a star collapsing and super
Speaker 1: slow motion. It's going to collapse to some point and
Speaker 1: then it's gonna bounce back and explode again, and it
Speaker 1: just hasn't happened yet because the black holes are in
Speaker 1: super slow motion. So this is the idea of a
Speaker 1: dark star and like the quantum version of a collapsing
Speaker 1: black hole that's gonna eventually bounce back. It just hasn't
Speaker 1: happened yet, right. I remember we talked about this, is
Speaker 1: that like it's the idea that maybe even black holes
Speaker 1: are don't exist, like maybe black holes aren't real, Like
Speaker 1: you never get to the actual black hole. You only
Speaker 1: have super dense star that is never going to collapse
Speaker 1: to a singularity. It's gonna blow it before it collapses.
Speaker 1: And you're saying, I think that that explosion, when it
Speaker 1: finally collapses, maybe a long time for now, you can
Speaker 1: call that a white hole. Exactly. This would be a
Speaker 1: transition from a black hole to a white hole because
Speaker 1: at that moment things would spray out. So you have
Speaker 1: this incredible source of energy, incredible source of radiation, and
Speaker 1: the curvature of space would be inverted so much so
Speaker 1: that it would effectively be a white hole. So I
Speaker 1: reached out to one of the authors of that paper,
Speaker 1: Francesco the Dotty. She wrote together actually with Carlo Rovelli,
Speaker 1: who has been a guest on our podcast as an
Speaker 1: excellent science writer, to ask her about what would happen
Speaker 1: if a black hole hit a white hole and the
Speaker 1: kind that she thinks about these quantum gravity white holes. Right,
Speaker 1: here's the audio professor Francesco the Dotty talking about quantum gravity. Okay,
Speaker 1: so we have to divide this question into two pieces,
Speaker 1: because it really depends whether we are talking about microscopic
Speaker 1: of macroscopic black holes. So let's imagine it's possible to
Speaker 1: have a too macroscopic object, one a black hole and
Speaker 1: one it's a vital and let's imagine that they are
Speaker 1: turning around one the other, very much like the black
Speaker 1: cobinaries that we are now proving with the gravitational ways
Speaker 1: telescopes like Lisa and so on. So in that case,
Speaker 1: what I would expect is just to have emerging between
Speaker 1: these two objects that is quite similar to what I
Speaker 1: would observe for the merging of two black holes. Then
Speaker 1: probably I'm not sure what the calculation would give exactly,
Speaker 1: but we have a prediction for the inkdown face. So
Speaker 1: after the two black holes merges, there is a specific
Speaker 1: wave form that we observe in gravitational ways. There could
Speaker 1: be differences for a black and a white all margin,
Speaker 1: but I expected something very similar and there is don't
Speaker 1: know why I expect something similar is because was in
Speaker 1: the moment in which a whitehall get perturbed by another
Speaker 1: object like a black hole, then very quickly the whitehall
Speaker 1: turns back into a black hole. So basically the two
Speaker 1: objects that would be emerging would be just two black holes.
Speaker 1: A completely different story is the case of two microscopic
Speaker 1: black and white oats. First of all, it's more complicated
Speaker 1: too created such a situation because being a microscopic well,
Speaker 1: it's not so easy maybe to create abounded the pair
Speaker 1: that would merge like in the microscopic case. And the
Speaker 1: other complication is that in the moment in which you
Speaker 1: have microscopic objects is not so clear the distinction between
Speaker 1: the black and the white one in the sense that
Speaker 1: you can have objects are so small that are basically
Speaker 1: at the Plank scale, the Planck scale, those objects behave
Speaker 1: like quantum objects. They are kind of quantum particle that
Speaker 1: have at the same time a black and the white
Speaker 1: nature like particles. So that could be in a superposition
Speaker 1: of spin up, a spin down, or if you want
Speaker 1: to like the shooting get that could be alive and
Speaker 1: at the same time. So those objects that can be
Speaker 1: black and white at the same time. So what you
Speaker 1: are marging are in fact a gray hole and another
Speaker 1: gray hole together. All right, thank you, professor Franchise Dirty
Speaker 1: it sounds like she's saying there are two scenarios here
Speaker 1: that can happen when a white hole, or a theoretical
Speaker 1: white hole hits a probably real black hole. Yeah, exactly,
Speaker 1: and one of them is actually the joke that you made, right,
Speaker 1: you might actually get a gray hole. Really, oh, I
Speaker 1: should get the Nobel price. Then the idea is if
Speaker 1: their macroscopic, they're like big classical objects, then they spiral
Speaker 1: in together. Then when they touch the black hole will
Speaker 1: convert the white hole into another black hole, and you'll
Speaker 1: get like a really big black hole. Basically the black
Speaker 1: hole eats the white hole and becomes a super black hole.
Speaker 1: What the black hole winds, basically the black hole winds exactly.
Speaker 1: And if they're microscopic, if they're super duper tiny, because
Speaker 1: you know, there's nothing stopping you from having a tiny
Speaker 1: black hole or a tiny white hole, then their quantum objects.
Speaker 1: Then quantum effects take over and they can be in
Speaker 1: this weird superposition where like each one could be like
Speaker 1: chance of being a black hole or chance of being
Speaker 1: a white hole, which is crazy, and that's what she's
Speaker 1: calling a gray hole. Wait, so it kind of depends
Speaker 1: on the sizes of these white and black holes. If
Speaker 1: they're really big, she said that the black hole would win.
Speaker 1: I guess, but why does it have to win. Why
Speaker 1: can't it just kind of switch together? Why does the
Speaker 1: black hole win? Because white holes are fragile objects. They're
Speaker 1: like not as stable as black holes in her conception
Speaker 1: of them. So but basically, a black hole is still
Speaker 1: collapsing star. It's like sucking all matter and it doesn't
Speaker 1: really matter what's your throw in there, another star, another
Speaker 1: black hole, even a white hole. Really like, what if
Speaker 1: I like a really really really big white hole and
Speaker 1: a tiny little black hole. Couldn't the white hole overwhelmed
Speaker 1: the tiny little black hole or what? The tiny little
Speaker 1: black holes still win. We're in the macroscopic region where
Speaker 1: we're ignoring quantum effects, and she's saying the black hole
Speaker 1: would win, that it would convert a white hole into
Speaker 1: another black hole. Well, no matter like how big or
Speaker 1: small each of them are, as long as you're above
Speaker 1: quantum properties. Yeah, and then the other scenarios, if we're
Speaker 1: tiny enough, the quantum effects take over. And again this
Speaker 1: is speculative because she's using the theory of quantum gravity,
Speaker 1: which we don't know if it's true or not. It's
Speaker 1: just like something we're thinking about. In that scenario, you
Speaker 1: could even stranger quantum effects, whether it be in a
Speaker 1: weird superposition of being a black hole or a white hole. Interesting,
Speaker 1: and this is if the white hole on the black
Speaker 1: hole are are really tiny, small enough, the quantum effects dominate.
Speaker 1: You know, we're talking about like particle size black holes
Speaker 1: and white holes. All right, well, I guess that answers
Speaker 1: the question then for Carson. Basically, Jorge was right. If
Speaker 1: the black hole in the white hole are small enough,
Speaker 1: then you get a little, tiny gray hole. But if
Speaker 1: they're big, then the black hole always wins and the
Speaker 1: whole thing turns into a giant black hole exactly, So
Speaker 1: it's not really much of a collision. I guess it's
Speaker 1: more like the black hole will always eat the white hole.
Speaker 1: That's the prediction, at least according to the quantum gravity expert.
Speaker 1: All right, well, thank you Carson for that great question,
Speaker 1: and thank you to all of our listeners who send
Speaker 1: in their questions. We love to answer them here on
Speaker 1: the podcast. We'd like you to think about the way
Speaker 1: the universe works, the way it might work, the way
Speaker 1: we pretend that it could work, and then to ask
Speaker 1: the questions about whether or not they are real. So
Speaker 1: if you have a question, feel free to send them
Speaker 1: to us. We might answer it here on the podcast,
Speaker 1: or Daniel's dog will answer the question. Apparently it's a
Speaker 1: pretty smart dog. You can be pretty rough sometimes with
Speaker 1: these answers. Well, we hope you enjoyed that. Thanks for
Speaker 1: joining us, see you next time. Thanks for listening, and
Speaker 1: remember that Daniel and Jorge Explain the Universe is a
Speaker 1: production of I Heart Radio. For more podcast For my
Speaker 1: heart Radio, visit the i heart Radio app, Apple Podcasts,
Speaker 1: or wherever you listen to your favorite shows.