Speaker 1: So I absolutely love talking about the tiniest little particles,
Speaker 1: the hearts of black holes, and how we could be
Speaker 1: misunderstanding like all of it.
Speaker 2: And I love talking about parasites, teeny tiny little wasps
Speaker 2: and dung beetles. But judging from my husband's face at
Speaker 2: the dinner table, it's possible that not everyone shares exactly
Speaker 2: my interests.
Speaker 3: So what do you want to hear about for the podcast?
Speaker 1: We usually pick topics that excite us and we think
Speaker 1: you'll enjoy, but you know we both have our weird
Speaker 1: quirks and preferences, so we want to hear from you.
Speaker 1: We'd love to answer questions you have about the universe,
Speaker 1: what you think is extraordinary and interesting and needs more explanation.
Speaker 1: Sometimes we turn your idea into a whole episode. Sometimes
Speaker 1: we give you a fifteen minute answer during a listener
Speaker 1: question session.
Speaker 2: And the questions you send us will help us more
Speaker 2: generally to gauge our audience's interests, which help us pick
Speaker 2: additional topics for the future.
Speaker 1: So please don't be shy I send us your questions.
Speaker 1: We want to hear from you. We want this podcast
Speaker 1: to be about what you are curious about, and today
Speaker 1: we're tackling three fantastic, hilarious, amazing questions send to us
Speaker 1: by listeners just like you, And if you want.
Speaker 2: To be on the next show, you can email us
Speaker 2: at Questions at Daniel and Kelly dot org.
Speaker 1: Your science podcast fame.
Speaker 2: Awaits Welcome to Daniel and Kelly's Extraordinary Universe.
Speaker 1: Hi. I'm Daniel, I'm a particle of physicist and I've
Speaker 1: never run out of questions.
Speaker 3: Hi.
Speaker 2: I'm Kelly Wiener Smith And every question I ask pleads
Speaker 2: to even more questions.
Speaker 1: Why is that? Do you think?
Speaker 2: Because we know so little about everything? I think at
Speaker 2: the end of the day.
Speaker 1: See, we even have questions about questions, there's never an
Speaker 1: end to them.
Speaker 2: So my question for you today, Daniel, is when you
Speaker 2: were working on a PhD, did you get a satisfying
Speaker 2: answer to your big question?
Speaker 1: You're really going to ask me that that's so embarrassing.
Speaker 1: You know. I did a PhD which was pretty technical.
Speaker 1: I was measuring how often two top quarks are made
Speaker 1: and decay in a very specific way. And it was
Speaker 1: only when I was writing up my thesis five years
Speaker 1: into the project that I did enough reading of the
Speaker 1: literature to understand, like, hey, is this interesting at all?
Speaker 1: And how am I contributing to the scientific conversation? And
Speaker 1: that's when I learned I basically wasn't. Oh no, So
Speaker 1: what did.
Speaker 3: You publish it? Anyway? I guess at that point you
Speaker 3: have to.
Speaker 1: Yeah, absolutely, you have to. And you know that's just
Speaker 1: part of the process, because when you start graduate school,
Speaker 1: you're like a science baby. I mean, you have your
Speaker 1: inspiration for why you want to study particles, but you
Speaker 1: don't know what the interesting questions are and what we
Speaker 1: could actually learn in a reasonable amount of time. So
Speaker 1: you rely on senior people the guide you and help
Speaker 1: you pick a time topic and get started on it.
Speaker 1: And so it was only when I finished my thesis
Speaker 1: that I feel like I knew enough to know what
Speaker 1: was interesting and what wasn't.
Speaker 3: Oh man, that's frustrating.
Speaker 2: I always tell the students that I work with, do
Speaker 2: you feel like you've read enough?
Speaker 3: Yeah? You haven't?
Speaker 2: Keep reading, go back and read, and they're like, no, no,
Speaker 2: I'm good. I'm like, oh, you're good, read twice as much.
Speaker 1: Are not good? Yet?
Speaker 2: You just need to keep reading. That solves a lot
Speaker 2: of problems. But man, it's hard to know when to stop.
Speaker 1: And that's why your book has such a lengthy bibliography.
Speaker 3: At least I practice what I preach.
Speaker 1: Yes, And how about you? Do you feel like your
Speaker 1: thesis was exciting, was compelling that you got to answer
Speaker 1: a big, fat, juicy question.
Speaker 2: I was asking whether or not this brain infecting parasite
Speaker 2: changes like some personality traits in the fish that it infects.
Speaker 2: And after like seven years it took me a really
Speaker 2: long time to get my PhD. The answer is like no.
Speaker 1: But you know, negative answers are just as important, right,
Speaker 1: you can't not publish it because the answers not exciting
Speaker 1: or not that interesting. It's important to cross things off
Speaker 1: the list. You know. I've been doing particle physics for decades.
Speaker 1: I've never discovered a new particle. Every single paper I've
Speaker 1: written is like, and we didn't find this, and we
Speaker 1: didn't find that, and we didn't find this other thing.
Speaker 2: I felt like I had designed a really good experiment,
Speaker 2: and so when I decided the answer was no, I
Speaker 2: was like, Oh, the ANSWER's really no.
Speaker 3: I feel good.
Speaker 2: About the answer being no, so yeah, no can be
Speaker 2: a satisfying answer. Also, but my PhD advisor would like
Speaker 2: me to finish publishing that paper.
Speaker 1: Wait, still are you joking, No, I mean it.
Speaker 3: Yeah.
Speaker 2: I've published a lot of side projects, and actually all
Speaker 2: of those side projects ended up becoming my dissertation. So
Speaker 2: we have had a lot of publications together, but the
Speaker 2: main project ended up being so massive and overwhelming and
Speaker 2: hard to analyze that I still haven't had a chance
Speaker 2: to write it up. But that is my twenty twenty
Speaker 2: five project, and that's why I wrote a bunch of
Speaker 2: my other collaborators to say, I'm not doing anything else
Speaker 2: this year.
Speaker 3: I'm finally going to publish my PhD.
Speaker 1: Was it also your twenty twenty project and your twenty
Speaker 1: fifteen projects? Yeah? Science takes a while, people, Science takes
Speaker 1: a while.
Speaker 2: It does, unfortunately, But you know what doesn't take a
Speaker 2: while sending an email to.
Speaker 3: You and me.
Speaker 2: That's right, and our amazing listeners have done that. And
Speaker 2: we have three fantastic questions today, all of them sort
Speaker 2: of more Daniel centric, but we've got a lot of
Speaker 2: Kelly centric questions queued up for our next Audience Questions episode.
Speaker 2: But should we jump into our first audience question today?
Speaker 1: Absolutely, let's do it. And as a reminder, we're going
Speaker 1: to be answering this question from a listener and then
Speaker 1: reaching out to the listener to give us a grade
Speaker 1: to see did we answer your question or did we
Speaker 1: just confuse even more or leave you unsatisfied with Nobody
Speaker 1: knows the answer, which is usually the way things turn out.
Speaker 3: But at least that's a real answer. So here we go.
Speaker 4: I have a question about the presence of super massive
Speaker 4: black holes in our galaxy. So my understanding is, we
Speaker 4: have evidence that a number of smaller galaxies have merged
Speaker 4: with the Milky Way in the past, right, and pretty
Speaker 4: much all galaxies have super massive black holes at their center, right,
Speaker 4: So what happened with those other black holes when they
Speaker 4: entered our galaxy? Unless it was a direct hit, they
Speaker 4: wouldn't have merged with our black hole immediately, right? So
Speaker 4: how long did this merger take? And in the interim
Speaker 4: it seems like there could have been just several super
Speaker 4: massive black holes flying through our galaxy circling the center.
Speaker 4: Do we have evidence of that happening? It seems like
Speaker 4: they must have left quite a path of destruction through
Speaker 4: the Milky Way. If not, is it strange that we
Speaker 4: can't find evidence of this? And could any still be
Speaker 4: out there right now?
Speaker 3: Wow?
Speaker 2: This is a super interesting and super informed question. Where
Speaker 2: do we start here, Daniel, Maybe we start with what
Speaker 2: happens when galaxies merge, because this was all sort of
Speaker 2: a new to me.
Speaker 1: Yeah, this is a really fascinating question, basically wondering like,
Speaker 1: why don't we see a bunch of black holes zooming
Speaker 1: around the center of the galaxy. Why does it seem
Speaker 1: like there's only one in the center of the Milky Way.
Speaker 1: Chris is a pretty sophisticated understanding of how galaxies merge,
Speaker 1: and that's suggests to him like there should be a
Speaker 1: bunch of black holes. And that's my favorite kind of
Speaker 1: question when you hear a listener having internalized something about
Speaker 1: physics and then drawing some conclusion, comparing that to the
Speaker 1: understanding and being like, wait, some thing's not fitting here.
Speaker 1: What am I missing? Because that's the essential process of science,
Speaker 1: right build that model compared to the data, update it.
Speaker 1: It's wonderful to see it happening in real time. So yeah,
Speaker 1: I agree we should start by reminding the listeners, at
Speaker 1: least who might not know as much as Chris does
Speaker 1: about how galaxies come together.
Speaker 2: Based on what you just said, I just want to
Speaker 2: confirm is it actually the case that every galaxy has
Speaker 2: a black hole at the middle, because I hadn't realized that.
Speaker 2: But we've seen a lot of galaxy, so we should
Speaker 2: know if that's a consistent thing or not.
Speaker 1: So that's a great question. We don't have a definitive
Speaker 1: answer because we can't look at every galaxy in the universe.
Speaker 1: But every single galaxy we've looked at has a supermassive
Speaker 1: black hole at the center, or we can explain where
Speaker 1: it went, like it got kicked out, or there's a
Speaker 1: collision or something. So there's very strong evidence that every
Speaker 1: galaxy has a super massive black hole, but it's not
Speaker 1: something we understand. If we try to model the formation
Speaker 1: of those black holes are the centers of galaxies, The
Speaker 1: models don't describe the data, like we can't get our
Speaker 1: black holes to be as big in the models as
Speaker 1: we see in reality, like they're huge black holes of
Speaker 1: the center of galaxies only a billion years after the
Speaker 1: universe forms. We have no idea how you make such
Speaker 1: a big black hole so quickly. So there's a lot
Speaker 1: we still don't understand about super massive black holes. For sure.
Speaker 2: Do we know why there's a super massive black hole
Speaker 2: at the center of every galaxy does that make sense.
Speaker 1: We don't know why they're so big, but it makes
Speaker 1: sense that. You know, galaxies are big pools of stuff,
Speaker 1: and stuff pulls on itself and falls towards the center,
Speaker 1: and eventually, if you get stuff dense enough, you're going
Speaker 1: to get a black hole. So it makes sense to
Speaker 1: have a black hole at the center of every galaxy.
Speaker 1: It's the densest point, and you cross that threshold, you
Speaker 1: get black holes.
Speaker 2: So yeah, okay, all right, So then let's back up
Speaker 2: to what happens when galaxies.
Speaker 1: Merg Yeah, because Chris is asking why we don't see
Speaker 1: multiple black holes at the center of the Milky Way
Speaker 1: from multiple galaxies merging, and this touches on the whole
Speaker 1: story of how galaxies form. We think that all the
Speaker 1: galaxies we see today are made up of a bunch
Speaker 1: of little baby galaxies that came together to make big galaxies.
Speaker 1: So we don't think big galaxies were formed all at
Speaker 1: once into some huge gravitational collapse in the early universe.
Speaker 1: We think that a bunch of little galaxies were made
Speaker 1: and then those galaxies come together to make bigger galaxies.
Speaker 1: It's like a hierarchical bottom up formation rather than just
Speaker 1: like a single formation of a big galaxy.
Speaker 2: Is it easy to explain why we think it started
Speaker 2: with little galaxies coming together as opposed to just lots
Speaker 2: of big galaxies forming.
Speaker 1: For a long time, there were both of those theories,
Speaker 1: the sort of top down and the bottom up approach.
Speaker 1: But you can tell the difference in the models, like
Speaker 1: the age of the stars and the formation and the
Speaker 1: structure of the galaxies are different if you start from
Speaker 1: little ones which then build up together to make big ones.
Speaker 1: And we can see evidence for this, for example, in
Speaker 1: our Milky Way, and surrounding the Milky Way, we see
Speaker 1: a bunch of little galaxies we call them dwarf galaxies
Speaker 1: that are not fully incorporated, that are sort of in
Speaker 1: the gravitational grasp of the Milky Way but not completely eaten.
Speaker 1: So we see a lot of evidence for this theory
Speaker 1: that galaxies are formed sort of bottom up.
Speaker 2: All right, So galaxies are formed bottom up. They all
Speaker 2: have super massive black holes at the center. I think
Speaker 2: we did talk in another episode about how sometimes galaxies merge,
Speaker 2: and this is one way the Earth we could all
Speaker 2: be in trouble if we got too close and we
Speaker 2: merged with another system that's coming back to me now.
Speaker 1: And so these supermassive black holes at the center. Just
Speaker 1: to remind folks, these are not little normal stellar black
Speaker 1: holes like a black hole that you think about from
Speaker 1: a collapsing star, Like a star burns up all of
Speaker 1: its gas and then it can no longer resist gravity
Speaker 1: and eventually collapses and forms a black hole. That's the
Speaker 1: kind of thing we expect to be like ten solar
Speaker 1: masses ten times the mass of our sun. Maybe a
Speaker 1: super massive black hole is something that's like ten thousand,
Speaker 1: or a million, or a billion times the mass of
Speaker 1: our Sun. So like really extraordinarily massive objects that are
Speaker 1: out there at the center of these galaxies. Even these
Speaker 1: dwarf galaxies have them up to like fifty thousand times
Speaker 1: the mass of our Sun.
Speaker 2: So if we know that dying suns cause black holes,
Speaker 2: how do we get super massive black holes. Is it
Speaker 2: like a dying sun party, like they all get together
Speaker 2: to see the sunset or something.
Speaker 1: We don't know the answer to that. Like, if you
Speaker 1: design a model, you say I'm going to use all
Speaker 1: the known physics we have and the gravity, and you
Speaker 1: create these galaxies, you get black holes at the center,
Speaker 1: But they don't get this big, like, they don't get
Speaker 1: as big as we see them out there in the universe.
Speaker 1: So they get massive, and we even call them super massive,
Speaker 1: but they don't get as big as we see so
Speaker 1: we don't understand exactly how they form. There's lots of
Speaker 1: crazy theories. One theory is that black holes may have
Speaker 1: formed much much earlier, they called primordial black holes, before
Speaker 1: even there was matter, when the universe was still cooling
Speaker 1: and coalescing. Instead of making protons, maybe it made a
Speaker 1: bunch of black holes. So the black holes are much
Speaker 1: older than we think, and they've been forming matter for
Speaker 1: a long time. Nobody's ever seen one of these primordial
Speaker 1: black holes, you know. There's a lot of ideas for
Speaker 1: how these black holes could have gotten so massive. But
Speaker 1: for Chris's question, the point is all of these galaxies
Speaker 1: come with a super massive black hole. So what happens
Speaker 1: to the black hole during the merger right when two
Speaker 1: galaxies come together make a bigger galaxy, to the black
Speaker 1: holes always combine? How long does that take? Why don't
Speaker 1: we see black holes in our milky way? This is
Speaker 1: super fascinating because black holes are really awesome objects and
Speaker 1: they're really massive, and the short version of the story
Speaker 1: is that we think galaxies come together and then black
Speaker 1: holes merge. We think that super massive black holes can
Speaker 1: merge into bigger black holes just the same way like
Speaker 1: two stars that are binary stars both collapse to black holes.
Speaker 1: They can combine into a bigger black hole, and we've
Speaker 1: seen evidence of the smaller black hole collapse in merger.
Speaker 1: That's where the famous gravitational waves are from. They're from
Speaker 1: two black holes orbiting each other, going faster and faster
Speaker 1: and faster as they coalesce into a bigger black hole.
Speaker 1: So we've seen gravitational waves from stellar mass black holes.
Speaker 1: And then last year we saw a lot of evidence
Speaker 1: a little bit less direct for gravitational radiation from super
Speaker 1: massive black hole mergers, which we think correspond to galaxy mergers.
Speaker 1: Super massive black holes at the hearts of galaxies coming together,
Speaker 1: swirling around each other, generating gravitational radiation, and then mentionally
Speaker 1: collapsing into a super duper massive black hole.
Speaker 2: Is this a possible explanation for why super massive black
Speaker 2: holes are bigger than theory predicts or has this already
Speaker 2: been explored?
Speaker 3: Like are they bigger?
Speaker 2: Because actually you're just looking at one and it was
Speaker 2: three that came together, or that doesn't explain it.
Speaker 1: No, that doesn't explain it. We include that in our model,
Speaker 1: and it can't describe the black holes that we see
Speaker 1: out there, not something else, some other process that's juicing
Speaker 1: them up. You know, there was this paper last year
Speaker 1: about how black holes could be causing dark energy, and
Speaker 1: this is correlation between the acceleration of the universe and
Speaker 1: the side the super massive black holes. But people don't
Speaker 1: really know if that's anything or nothing. There are papers
Speaker 1: examining like the size of the bulge in the galaxy
Speaker 1: and the size of the black hole. Those seem to
Speaker 1: be correlated, which suggests that it's not just something local,
Speaker 1: it's a bigger process across the galaxy. It's very active
Speaker 1: area of research, and in a few years I think
Speaker 1: we'll know a lot more because we're gathering a lot
Speaker 1: more data about super massive black hole mergers from these
Speaker 1: pulsar timing arrays. You use the whole galaxy basically as
Speaker 1: a gravitational wave detector by looking at how the gravitational
Speaker 1: waves ripple across pulsars. It's really super interesting. One of
Speaker 1: the most fascinating things to me is that we actually
Speaker 1: don't understand how these supermassive black holes merge. Like theoretically,
Speaker 1: it's a little complicated when they get really close together.
Speaker 2: I mean, when they get really close together, I guess
Speaker 2: I would just assume that they like attract each other
Speaker 2: and just like pull each other into each other.
Speaker 3: Or is that too simple?
Speaker 1: No, you're exactly right. And if they're heading right towards
Speaker 1: each other, boom, they just suck into each other. But
Speaker 1: remember they're moving asked already, and if they're not exactly
Speaker 1: angled at each other, they're gonna end up orbiting each other. Right,
Speaker 1: there's gonna be angular momentum. They're spinning around each other. Basically,
Speaker 1: if one black hole passes by the other one instead
Speaker 1: of hit directly hitting it, it's gonna swing around and
Speaker 1: the two are gonna end up orbiting each other. Now,
Speaker 1: if those black holes are surrounded by a bunch of
Speaker 1: other stars, then they're gonna lose energy and they're gonna
Speaker 1: fall towards each other. And you might be thinking, well,
Speaker 1: what about the gravitational radiation is not gonna sap the
Speaker 1: black hole's rotational energy so that they end up falling
Speaker 1: towards each other. Yeah, that's true. That happens, but that's
Speaker 1: not a lot of energy. It's not fast enough to
Speaker 1: explain how they actually fall together. What they need is
Speaker 1: the friction, the tugging from stars and gas and dust
Speaker 1: to slow them down and help them fall in. Gravitational
Speaker 1: waves are not enough. But when they get really close
Speaker 1: and there's no other stars and it's just two black
Speaker 1: holes orbiting each other, we don't understand why they eventually collapse.
Speaker 1: We think that's a stable situation, like two black holes
Speaker 1: orbiting each other with out any stars to slow them
Speaker 1: down or whatever, they should do that for a long
Speaker 1: long time, we don't really understand why they close that
Speaker 1: final gap. We know that it happens because we've seen
Speaker 1: evidence gravitational waves from those mergers, but theoretically it doesn't
Speaker 1: quite make sense. It's called the final parsec problem. It's
Speaker 1: still an open question right now in physics.
Speaker 2: And I'm assuming that we don't have a lot of
Speaker 2: these instances where you have two black holes orbiting each
Speaker 2: other that you can look at to try to get data,
Speaker 2: because that's probably a pretty rare thing to see.
Speaker 1: It is hard to see because super massive black holes
Speaker 1: are in galaxies far far away, and it's very difficult
Speaker 1: to see these things and observe them, and the timescale
Speaker 1: of these things is very, very long, so we have
Speaker 1: not yet detected individuals supermassive black hole mergers. What we've
Speaker 1: detected with these gravitational wave observatories that span the galaxy
Speaker 1: is like a general hum from lots and lots of them,
Speaker 1: so we know that it's happening. But if we can
Speaker 1: get data from an individual and you're absolutely right, and
Speaker 1: track like what's happening over those last few seconds, we
Speaker 1: could learn a lot about how these things collapse. And
Speaker 1: so it's something we haven't understood. But still now to
Speaker 1: answer Chris's question, now that we have sort of the
Speaker 1: background on like how these galaxies merge and how the
Speaker 1: black holes mysteriously merge, even though don't quite understand it,
Speaker 1: Chris is basically asking, if the Milky Ways made up
Speaker 1: of all these galaxies, and those galaxies have black holes
Speaker 1: and they merged, why don't we see a bunch of
Speaker 1: black holes at the center of the galaxy instead of
Speaker 1: just one right, And the answer is that the Milky
Speaker 1: Way hasn't had a big collision recently for some reason.
Speaker 1: The Milky Way is pretty smooth and chill. There hasn't
Speaker 1: been a lot of activity. So if we had recently,
Speaker 1: in the last you know, a few hundred million years,
Speaker 1: collided with a big Mama galaxy, then yes, we probably
Speaker 1: would have two supermassive black holes at the center swirling
Speaker 1: around each other and we could watch it happen and
Speaker 1: maybe learn something about this final parsec problem. But we're
Speaker 1: sort of lucky, I guess, in that over the last
Speaker 1: few billion years we haven't had as many collisions, which
Speaker 1: is probably one reason why we're not as big. Like
Speaker 1: if you look at Andrama, the nearby galaxy much bigger
Speaker 1: than the Milky Way, it's a big Mama galaxy and
Speaker 1: pretty soon at you in a few billion years, we
Speaker 1: are going to collide with it and form some super
Speaker 1: duper galaxy. But we're I guess a little bit quieter
Speaker 1: and a little bit smaller, and that's the reason we
Speaker 1: don't have surviving multiple super massive black holes at the center.
Speaker 2: And just to be clear, the physicist in you would
Speaker 2: really like to be around when our galaxy merges with
Speaker 2: another m H but Kelly and her children would not
Speaker 2: want to be around because that could be a very
Speaker 2: chaotic time.
Speaker 3: Is that right?
Speaker 1: That would be a very chaotic time. Yeah, exactly. You know,
Speaker 1: even though it would be far away, like the collision
Speaker 1: of two galaxies doesn't necessarily involve a collision of stars directly.
Speaker 1: It's a lot of gravitational perturbation. And we talked in
Speaker 1: a whole other episode about what that would be like,
Speaker 1: and it's pretty risky stuff. But yes, we would learn
Speaker 1: so much about black holes and how they work, and
Speaker 1: how galaxies form, and the history of the universe and
Speaker 1: our place in it, and it would be totally worth it.
Speaker 1: Sorry for your children, I.
Speaker 3: Don't think it's going to happen in our lifetime. So
Speaker 3: we're right.
Speaker 2: So let's reach out to Chris and see if this
Speaker 2: answered his question, and then we're going to take a
Speaker 2: break before we come back for a question about setting
Speaker 2: off nuclear weapons in extreme weather events.
Speaker 1: So I sent our answer to Chris and he wrote
Speaker 1: back to me in an email to say, quote, that
Speaker 1: was a great discussion and a very satisfying answer. Thank you,
Speaker 1: So thank you, Chris, and you're welcome.
Speaker 3: All right, and we're back.
Speaker 2: Our next question is from Margie, and this one is
Speaker 2: a doozy.
Speaker 5: The other day I heard that a certain politician wanted
Speaker 5: to use nuclear bombs to get rid of hurricanes. Politics aside.
Speaker 5: Even though it's a bad idea, it made me wonder
Speaker 5: what would happen if a nuke went off in a
Speaker 5: hurricane blow it out? What about the radiation in the ocean.
Speaker 1: Thanks, this is a really fun question, and it's what
Speaker 1: I've heard a few times people talking about. So I thought,
Speaker 1: you know what, let's handle this out on the podcast
Speaker 1: in case somebody out there with their finger on the
Speaker 1: nuclear button happens to be a listener.
Speaker 3: H all right.
Speaker 2: So I thought that this was an incredible question. As
Speaker 2: soon as I write it, I was like, oh, yeah,
Speaker 2: I absolutely want to know the answer to this. And
Speaker 2: you said you've heard this question before. This was totally
Speaker 2: new to me. So let's start with how hurricanes even work.
Speaker 2: If we want to talk about how you would blow
Speaker 2: one out, let's know how they get started.
Speaker 1: Yeah, hurricanes are amazing demonstration of pretty basic physics. You know.
Speaker 1: Its heat flow combined with the rotation of the Earth
Speaker 1: gives you this effect. And there's a little bit of
Speaker 1: a naming thing going on here. The broader category is
Speaker 1: called a cyclone, and if it's in the Atlantic or
Speaker 1: the Northeastern Pacific, then you call it a cyclone. The
Speaker 1: same storm in the northwestern Pacific you call it typhoon.
Speaker 1: And if it's in the South Pacific or the Indian Ocean,
Speaker 1: you call it a tropical cyclone. So you may have
Speaker 1: heard all of these terms. They're actually all the same thing.
Speaker 1: They're all just cyclones. Hurricanes are like our version of them.
Speaker 3: Why why did they do that?
Speaker 2: Were they described by different groups living in different areas
Speaker 2: at different times and those names just stuck or science
Speaker 2: sometimes goes a little crazy with our jargon.
Speaker 3: Is that what happened to here?
Speaker 1: It's actually really fun because we're not one hundred percent
Speaker 1: clear why we have three names. I mean, the most
Speaker 1: likely general explanation is the same reason why we have
Speaker 1: like multiple names for carbonated beverages coke or soda or pop.
Speaker 1: They originate in different groups organically, and then it becomes
Speaker 1: hard to reconcile once we realize, hey, these are all
Speaker 1: the same thing. We think the word hurricane comes from
Speaker 1: the Caribbean god Hourcan or the Mayan god of wind hurrican.
Speaker 1: I might be mispronouncing those, and then the words were
Speaker 1: later adopted by Spanish colonizers. The word cyclone comes from
Speaker 1: the Greek word cuclos, which means circle. It was coined
Speaker 1: in eighteen forty by Henry Pittington of the East In
Speaker 1: Company to describe storms in the South Pacific and typhoons.
Speaker 1: That word doesn't have a clear origin. It might be
Speaker 1: from the Greek name of a monster associated with the wind,
Speaker 1: or a Persian word that means to blow furiously, or
Speaker 1: we don't know exactly where that word comes from. We're like, oh,
Speaker 1: that's actually the same thing. You call it a hurricane,
Speaker 1: we call it a typhoon. Let's call the whole thing off.
Speaker 1: But you know, sometimes in science it's more dramatic than that.
Speaker 1: There's like competing groups and we think it's called the typhoon,
Speaker 1: we call it a hurricane. And then you know their
Speaker 1: minions propagate this kind of stuff. And we had an
Speaker 1: event like that in particle physics, were the same particle
Speaker 1: named by two different people, And these days we give
Speaker 1: it both names because we couldn't settle the debate.
Speaker 2: We have species descriptions like that. Two people didn't realize
Speaker 2: they were naming the same species. But whoever got their
Speaker 2: paper published first has precedents. I think maybe it differs
Speaker 2: by field. Maybe the person who did it better. But anyway,
Speaker 2: I've been reading papers from the nineteen hundreds and sometimes
Speaker 2: they even do name calling and stuff. It's intense, but okay,
Speaker 2: all right, so different names, it's all cyclones.
Speaker 3: You say tomato, I say tomato.
Speaker 1: Yeah, exactly what causes them? So a cyclone basically comes
Speaker 1: from warm water. It heats and moistens the air above it. Right,
Speaker 1: so the ocean is warm, you get hot air above it.
Speaker 1: That hot air rises. That causes low pressure because the
Speaker 1: air is going up. So now more air is going
Speaker 1: to move in. So you have this effect where air
Speaker 1: is getting sucked in and pushed up.
Speaker 5: Right.
Speaker 1: The second step is to get it to spin. The
Speaker 1: reason it's spinning is because the Earth itself is spinning.
Speaker 1: And this is super fascinating. It comes because the atmosphere
Speaker 1: at different latitudes is spinning at different velocities. Like think
Speaker 1: about how fast the atmosphere is moving at the poles
Speaker 1: where the Earth is spinning. It's just in place, right.
Speaker 1: An air molecule above the north pole is not moving anywhere.
Speaker 1: But an air molecule above the equator it's sticking with
Speaker 1: the land. It's going a lot faster, right, So the
Speaker 1: air velocity depends on the latitude. The closer yurdit equator,
Speaker 1: the fast you're going, the closer yard of the poles,
Speaker 1: the slower you're going. All right, that's cool. Now, what
Speaker 1: happens if you're sucking air in imagine this cyclone. We
Speaker 1: have a low pressure region, we're sucking air in from
Speaker 1: the north, and we're sucking air in from the south. Well,
Speaker 1: the air that's coming from the south, if you're in
Speaker 1: the Northern hemisphere, is going to be moving faster, and
Speaker 1: the air that's coming from the north is going to
Speaker 1: be moving slower. So the air moving from the north
Speaker 1: is moving slower, it falls behind. The air moving from
Speaker 1: the south is moving faster. It gets sped up, and
Speaker 1: that's where the spin comes from. And that's why they
Speaker 1: spin the opposite direction. In the Southern hemisphere toilet thing exactly,
Speaker 1: the famous fallacious toilet thing. But this is actually true, right,
Speaker 1: if you could flush your toilet with a hurricane, it
Speaker 1: actually would flush a different direction in the northern Southern hemisphere,
Speaker 1: except you couldn't call it a hurricane. You could call
Speaker 1: it like a tropical cyclone in the South Pacific. So yeah,
Speaker 1: in the northern hemisphere, they spin in a different direction
Speaker 1: and in the southern hemisphere. Super cool.
Speaker 2: Okay, And let's be clear for anyone who missed that
Speaker 2: toilets do not flow opposite directions in different hemispheres, because
Speaker 2: it's all about the way the holes are put in
Speaker 2: the toilet, see right, and that just makes it go
Speaker 2: in one direction.
Speaker 1: I have no idea how it actually works. I just
Speaker 1: know that it's apocryphal. Okay, Yeah, But so that's the
Speaker 1: basic mechanism or hurricane, right, starts with warm water, you
Speaker 1: get air rising, air rushes in from the sides. It's
Speaker 1: coming in at different speed, so it ends up spinning.
Speaker 1: So it's spinning because the Earth is spinning. Like if
Speaker 1: the Earth didn't spin, we wouldn't have hurricanes or cyclones
Speaker 1: or typhoons or any of that kind of stuff.
Speaker 2: Okay, So ways to disrupt this weather pattern would either
Speaker 2: be to like mess with the temperature or to like
Speaker 2: put a giant fan in there trying to counteract the spin.
Speaker 3: But we're talking about nukes, so nukes would heat things up.
Speaker 3: Could that stop it?
Speaker 1: I love the idea of using nukes because it's like,
Speaker 1: what's the biggest thing we got? We have this hammer?
Speaker 1: What can we do with it? I mean, you see
Speaker 1: this in space all the time. People are like, how
Speaker 1: do we power spaceship? What if you blow up nukes
Speaker 1: behind it? And that's actually not a crazy idea, right,
Speaker 1: We're going to talk about that pretty soon the podcast.
Speaker 2: Well in Project Cloudshares was a whole project in the
Speaker 2: US to figure out what you could use nuclear weapons for.
Speaker 2: We use them to build like bays and stuff like that, Like,
Speaker 2: let's blow that up too, Okay, So anyway, what about
Speaker 2: a hurricane?
Speaker 1: So it's not completely insane on the face of it,
Speaker 1: because what is a hurricane? You have a hotspot. It's
Speaker 1: all about energy flow, right, This warm air heated by
Speaker 1: the ocean is rising and all this stuff is coming in.
Speaker 1: So if you could like disrupt that somehow, if you
Speaker 1: could create hotspot somewhere else, or move the heat or
Speaker 1: disperse it or something, could you disrupt this flow? So
Speaker 1: it's not insane, right, It's not just like, hey, I'd
Speaker 1: love to nuke that, let's do it. But the problem
Speaker 1: is that hurricanes a our energy flow on a much
Speaker 1: much bigger scale than even our nuclear bombs. Like there
Speaker 1: is so much energy captured in a hurricane. I looked
Speaker 1: it up. Hurricanes release like one hundred tarawatts of energy,
Speaker 1: and the global power use annually is twenty five tarrawats.
Speaker 1: So like, this is an enormous amount of energy. It's
Speaker 1: four times as much as like human use.
Speaker 2: Okay, so the biggest nuclear bomb ever exploded was by
Speaker 2: the Soviet Union.
Speaker 3: It was tzar bomba right, mm hmm. How does that compare?
Speaker 1: So you would have to blow that guy up every
Speaker 1: twenty minutes to compare to the energy of a hurricane. Wow,
Speaker 1: So it's a big deal. Like a hurricane is just
Speaker 1: a massive movement of air. It's because the mass. Well,
Speaker 1: there are high speeds as well. You know, these winds
Speaker 1: can get to hundreds of miles per hour, but it's
Speaker 1: just such a huge mass. I mean, you can see
Speaker 1: the things from space, right, it's big. And anytime you
Speaker 1: have something really big moving high speed, there's a lot
Speaker 1: of energy and it would take an enormous amount of
Speaker 1: energy to deflect it. So if you're going to nuke,
Speaker 1: it's going to require like all of the Earth's arsenal
Speaker 1: dropping down on this thing. It's not like a single
Speaker 1: tactical nuke is going to deflect this thing. You want
Speaker 1: to have an impact, it's going to have to be huge,
Speaker 1: and then you're causing a nuclear winter. So I don't
Speaker 1: think you really accomplish an.
Speaker 2: You haven't solved any problems there. We started by saying
Speaker 2: that cyclones are because of heat. Is it possible that
Speaker 2: by trying to stop a cyclone when we set a
Speaker 2: nuclear weapon off, we're just gonna make it worse because
Speaker 2: that's more heat. Oh yeah, is that what would happen
Speaker 2: or we don't know if it would get worse.
Speaker 1: Well, hurricanes are not something we totally understand right anyway.
Speaker 1: We can't like look at a hurricane and say we
Speaker 1: know what's going to happen here because we understand all
Speaker 1: the physics. We understand the microphysics, but it's such a
Speaker 1: chaotic system that a little wrinkle here, a butterfly flaps,
Speaker 1: that swings there, the hurricane goes somewhere else. These things
Speaker 1: are difficult to model. We think that probably what would
Speaker 1: happen is you'd produce a shockwave a pulsive high pressure,
Speaker 1: but we don't think that would actually have a big
Speaker 1: effect on like the pressure of a hurricane. In order
Speaker 1: to change like a big category five hurricane, you do
Speaker 1: a category two hurricane. You'd have to add like a
Speaker 1: half ton of air for each square meter inside the
Speaker 1: eye of the hurricane, which is like five hundred million
Speaker 1: tons of air. So you know, it's hard to imagine
Speaker 1: like moving that much air around in terms of like
Speaker 1: changing the pressure. We don't have like the tool to
Speaker 1: do this right. And you know, fundamentally, like you have
Speaker 1: a big warm spot in the ocean, unless you're going
Speaker 1: to completely disperse that heat, you might temporarily disorganize a hurricane,
Speaker 1: but the same forces that create it are just going
Speaker 1: to reorganize it. I mean, as you say, like you're
Speaker 1: adding heat usually to the system, and so it's just
Speaker 1: going to come back stronger, you know, like a monster
Speaker 1: in a terrible movie. Plus you're gonna have like dumped
Speaker 1: a bunch of radiation into your atmosphere, a very high
Speaker 1: velocity winds that are going to go everywhere, all right.
Speaker 2: So you have just made me even more amazed that
Speaker 2: there are some people who don't evacuate when hurricanes come through,
Speaker 2: because I hadn't realized how much stronger they were than
Speaker 2: the explosions of nuclear weapons. We've established that heat equals
Speaker 2: bad in this case, can you cool it down?
Speaker 3: Somehow.
Speaker 2: I'm guessing the answer is no, because this is just
Speaker 2: energy on a scale that is uncontrollable. Yeah, has anyone
Speaker 2: ever tried to like cool it down?
Speaker 1: So the US government has sponsored a bunch of projects
Speaker 1: to try to in your with hurricanes, which makes sense,
Speaker 1: like these are destructive things. Is there anything we can do?
Speaker 1: And in the sixties there's this project called storm Fury,
Speaker 1: which is a pretty awesome name, where the thought was,
Speaker 1: could we somehow disrupt the flow because the hurricane has
Speaker 1: these walls as of clouds circulating around the center, And
Speaker 1: they thought if they maybe seated the clouds by dumping
Speaker 1: in a bunch of silver iodied, which nucleates ice crystals,
Speaker 1: that this silver iodied would make these ice crystals, which
Speaker 1: could make like a new ring of clouds, which would
Speaker 1: somehow compete with the natural circulation of the storm and
Speaker 1: basically disorganize it, sort of actually releasing some of the
Speaker 1: heat by forming these ice crystals, right, releasing some of
Speaker 1: that water, and then like growing the rainy part instead
Speaker 1: of this spinny part. The idea was sort of reasonable,
Speaker 1: and they actually tried it on a few hurricanes, but
Speaker 1: it didn't work. And these days we think that probably
Speaker 1: it failed because there isn't enough super cooled water to
Speaker 1: react with that silver iodide to have enough of an effect.
Speaker 1: And so people have tried stuff, nobody's ever made it work.
Speaker 1: But you know, people are out there thinking about how
Speaker 1: can we protect ourselves from hurricanes? What are some things
Speaker 1: we can do? To me? This is kind of scary.
Speaker 1: It's in the category of like geoengineering, right, like, hey,
Speaker 1: should we put something in our atmosphere to reflect sunlight?
Speaker 1: Like you're dumping a lot of stuff into a storm.
Speaker 1: It could have a big effect. You have no idea
Speaker 1: where that storm is going to go, and then you
Speaker 1: feel responsible for it. Right What if the storm was
Speaker 1: going to hit a fairly uninhabited area and then you
Speaker 1: steered it towards New York City, Now you're responsible for that.
Speaker 1: So I don't know whether it's a good idea or not.
Speaker 3: I don't know either, you know.
Speaker 2: I actually I love to have a whole episode on
Speaker 2: geoengineering stuff because it is so tempting. What if there
Speaker 2: was some way that we could all just keep doing
Speaker 2: exactly what we're doing, but just like throw some stuff
Speaker 2: in the sky to take care of it. But yeah,
Speaker 2: I don't think we understand things well enough.
Speaker 1: Yeah, but they did, and in the sixties they did
Speaker 1: it for Hurricane Esther and Hurricane Bulah, Hurricane Debbie, and
Speaker 1: then Hurricane Ginger in nineteen seventy one. I wasn't able
Speaker 1: to find more recent experiments. I don't know if those
Speaker 1: are like still classified or whatever, but it's definitely something
Speaker 1: people tried. Nobody's ever tried a nuke a hurricane as
Speaker 1: far as I'm aware, which I'm grateful for. Though I
Speaker 1: know that our president elect it's an idea that he
Speaker 1: bounced around within his previous administration.
Speaker 2: Well, I hope he listens to our podcast and we
Speaker 2: can help out in that way.
Speaker 1: I also remember seeing videos during some recent hurricane in
Speaker 1: Florida of people shooting the hurricane. It seems like, I
Speaker 1: get what you're expressing your frustration and this is the
Speaker 1: only tool you have, But like, you don't want the
Speaker 1: hurricane picking up those bullets and throwing them at high
Speaker 1: speeds at anything. So don't shoot hurricanes people with nukes
Speaker 1: or with bullets or really anything. Just get out of there.
Speaker 3: Yeah, don't contribute to the problem.
Speaker 1: Just leave.
Speaker 2: That's sound advice there. So let's see what Margie thinks
Speaker 2: of our sound advice and see if she felt like
Speaker 2: this was a good answer.
Speaker 1: Maybe we can convince her to slowly slide her finger
Speaker 1: off of that big red button.
Speaker 2: I wonder how much power Margie has, Sparis Margie. All right, Well,
Speaker 2: here Margie's response, and then we'll take a break.
Speaker 6: Wow, I'm a little surprised that it would just reform
Speaker 6: after a blast. But let's say a nuke was shot
Speaker 6: off in a hurricane in the middle of the ocean
Speaker 6: and then it started spreading radiation.
Speaker 1: All over the place.
Speaker 6: Would it still be spreading radiation when it came ashore.
Speaker 1: Very glad we were able to answer your question, Margie,
Speaker 1: And that's a great follow up question. Yeah, it would
Speaker 1: be very bad to release a lot of radiation into
Speaker 1: a hurricane. The sort of long range danger from a
Speaker 1: bomb going off is exactly having high winds which spread
Speaker 1: those radiactive materials around, and so dropping one into a
Speaker 1: hurricane it's basically the worst case scenario for containing that radiation.
Speaker 1: So yeah, the winds in the water would spread that
Speaker 1: radiation really far and cause a lot of damage. Again,
Speaker 1: not a good idea. Please don't drop a bomb into
Speaker 1: a hurricane.
Speaker 2: So Our next question is from Kevin, So here we go.
Speaker 7: This is a Kevin from Shoay, China, and I'll have
Speaker 7: a question about philosophy. If a photon turns into the
Speaker 7: electron and a positron, and the electron and positron and
Speaker 7: wiolates into another photon, are the two photons exactly the same?
Speaker 7: If they are the same, how can the photon appear
Speaker 7: and disappear out of the air. And if they are
Speaker 7: the same, is there a point when the first becomes
Speaker 7: a second?
Speaker 1: Ooh, thank you Kevin for asking such a fun physics
Speaker 1: slash philosophy question.
Speaker 2: Totally love this one, and I absolutely love hearing that
Speaker 2: we have international listeners. This totally made my day. And
Speaker 2: Daniel is clearly the right guy to answer your question.
Speaker 2: So what's happening Daniel?
Speaker 1: So what's going on here is that photons, when they
Speaker 1: fly through space, you might just imagine like, hey, it's
Speaker 1: a little packet of energy. It wiggles through space. That's it, right,
Speaker 1: But we also talk about photons doing other stuff, like
Speaker 1: photons can fly along and then we say sometimes they
Speaker 1: can turn into a pair of particles called this conversion.
Speaker 1: Like a photon is flying along and it turns into
Speaker 1: an electron and a positron, two particles, so maintaining the
Speaker 1: overall charge of zero, and then those particles can annihilate,
Speaker 1: they can turn right back into a photon. So you
Speaker 1: can imagine like either just a photon flying along which
Speaker 1: turns into like a little loop of particles and then
Speaker 1: turns back into a photon. And Kevin is asking, like,
Speaker 1: what does that mean about the photon? Is that the
Speaker 1: same photon that comes out after this particle loop or
Speaker 1: is it not? And if it's not, then like, exactly
Speaker 1: when does the new photon get born?
Speaker 2: So is this philosophically the same as the transporter problem.
Speaker 1: It's actually very similar to the transporter and it touches
Speaker 1: on you know, what do you mean by this photon?
Speaker 1: And how do you kill a photon? And all sorts
Speaker 1: of stuff, and because in the end, these are quantum processes, right,
Speaker 1: And the transporter problem in the end comes down to
Speaker 1: like any time an object moves from place to place,
Speaker 1: it's equivalent to making a copy of it and destroying
Speaker 1: the old one, especially if we're all just ripples in
Speaker 1: quantum fields, it's just your information sliding along. And so
Speaker 1: basically every moment in your life. You're being transported through
Speaker 1: space and time the same way a teleporter works, just
Speaker 1: smaller distances. And so yeah, does that matter? Are you
Speaker 1: being killed every instant and being recreated some other place?
Speaker 1: What does that mean about being killed? I don't know anyway,
Speaker 1: it's a big rabbit hole of philosophy. But here we're
Speaker 1: focusing on a single photon.
Speaker 2: Okay, so you're not going to answer that question for
Speaker 2: us by the end of this answer. What do we
Speaker 2: mean then by same If it's the same photon, what
Speaker 2: would that mean?
Speaker 1: Yeah, so there's two issues here we have to grapple
Speaker 1: with if we're going to think about what this means,
Speaker 1: and that's one of them. And the short answer, the
Speaker 1: big picture answer to this question is that there is
Speaker 1: no good answer to this question because the picture that
Speaker 1: I just described, and that Kevin probably has this head
Speaker 1: and a lot of people think about for photons, it's
Speaker 1: a cartoon picture. It's not like our microphysical explanation for
Speaker 1: what's really happening. Like you know, in biology, you can
Speaker 1: have a microscopic explanation. You can say, oh, the reason
Speaker 1: you're sick is a virus came in and attacked your
Speaker 1: cell and to penetrated the cell wall, and you can
Speaker 1: have this picture in your mind of these tiny things
Speaker 1: happening that explain what we're experiencing on the big scale,
Speaker 1: and that can be reality. So if you like zoom
Speaker 1: in with a microscope, you can actually watch it. That's awesome, right,
Speaker 1: And we try to do the same thing in physics,
Speaker 1: provide a microscopic explanation for what we think is happening,
Speaker 1: and that can be very satisfying, but it's sometimes a
Speaker 1: cartoon and it's misleading because what's happening in the microscopic
Speaker 1: scale is fundamentally, very very different from what's happening in
Speaker 1: biology or in the classical scale. It's not like tiny
Speaker 1: little balls or bouncing off each other or converting into particles.
Speaker 1: You can't slow these things down and watch them like
Speaker 1: a movie and get a version of the microscopic story.
Speaker 1: So you know, what we mean by a photon isn't
Speaker 1: just like a photon is flying through space, or a
Speaker 1: photon flies through space and makes a particle loop. It's
Speaker 1: sort of all of those things mixed together. So that's
Speaker 1: why we have to identify what we mean by a
Speaker 1: photon and what we mean by same.
Speaker 2: So does this go back to our what is a
Speaker 2: particle discussion? And do they work as waves or strings
Speaker 2: or so? The question is hard to answer because we
Speaker 2: don't even really know how to describe these things.
Speaker 1: Yeah, exactly, and Kevin is picking out one aspect of
Speaker 1: that cartoon, and really a photon is all of those things.
Speaker 1: So let's start by talking about what a photon is,
Speaker 1: and then we can dig into what do we mean
Speaker 1: by the same photon. Okay, if you think about a photon,
Speaker 1: it's just you're thinking about a single packet of light
Speaker 1: that goes through space quantum mechanically. Kevin is right that
Speaker 1: the photon could do that, but it could also convert
Speaker 1: into these par of particles and go back. It could
Speaker 1: also convert into those pair of particles, and then those
Speaker 1: particles emit photons, which then turn into other stuff and
Speaker 1: turn into other stuff. There's an infinite number of things
Speaker 1: that a fon could do when it goes from A
Speaker 1: to B, and each of those things comes with a probability.
Speaker 1: And when we talk about the photon, we don't mean
Speaker 1: one of those particles in one of those stories. What
Speaker 1: we really mean is that whole bundle. We mean the
Speaker 1: whole thing all mixed together because we don't know what's happening,
Speaker 1: and there is no what's really happening the photon. The
Speaker 1: thing we think about, the thing we should identify with
Speaker 1: is all of those possibilities, not any individual one of
Speaker 1: them or any part of them.
Speaker 2: So when we were doing the what is a Particle episode,
Speaker 2: we talked about how you don't explain the wave theory
Speaker 2: of how you describe particles until grad school. And so
Speaker 2: this question is making me wonder how the fact that
Speaker 2: we are all taught to think about these as like
Speaker 2: little points that are moving around, how much does that
Speaker 2: inhibit all of our abilities to think about these things?
Speaker 2: Like should we be changing the way we address this
Speaker 2: in high school? I know it's much harder to explain
Speaker 2: it as a wave, but it's wrong. It sounds like
Speaker 2: the way we explain it.
Speaker 1: Yeah, quantum field theory in kindergarten. That's what I think. No,
Speaker 1: it's a great question, and I think you're right, And
Speaker 1: you see it in physics students as they learn this stuff,
Speaker 1: you teach them to think about particles and then you're like, actually,
Speaker 1: all your intuition is wrong. You have to unpack that
Speaker 1: and learn this whole other thing. And you know, I'm
Speaker 1: very interested in physics education. We have these conversations like
Speaker 1: what is the right order to teach people in, But
Speaker 1: there's sort of this canonical order that everybody uses that
Speaker 1: sort of follows the historical development. It's like, we thought this,
Speaker 1: then we thought that, then we thought that, And as
Speaker 1: you move through your physics education, you sort of catch
Speaker 1: up to modernity. And I think it is important to
Speaker 1: understand where these ideas came from, like why people thought
Speaker 1: this and why people thought that, because just like with
Speaker 1: the names of hurricane and typhoon, there's a lot of
Speaker 1: like weird, patchy stuff that doesn't really make sense unless
Speaker 1: you understand the history. So you kind of got to
Speaker 1: teach people the current ideas, but you also want to
Speaker 1: give them a tour of how we got here so
Speaker 1: they can understand why some of it seems weird and ugly.
Speaker 1: So I don't know the right answer to your question.
Speaker 2: Okay, I mean I see no reason why we couldn't
Speaker 2: start with here's the wave theories and string theories of
Speaker 2: particles and then after be like, well, here's the history.
Speaker 2: Let's talk about how we got here m hm, so
Speaker 2: that people would be less confused. But anyway, I'm not
Speaker 2: a physics educator, but I guess I kind of am.
Speaker 1: Yeah, I guess that we have opinions at least. So
Speaker 1: in that episode about a particle, we also talked about
Speaker 1: how you can think about particles, as you know, little
Speaker 1: dots flying through space turning into other stuff. You could
Speaker 1: also think of them as fields. Right, instead of imagining
Speaker 1: a bit of stuff, imagine a field feeling the universe,
Speaker 1: and particles are ripples in those fields, and those two
Speaker 1: things are actually mathematically equivalent. You can think about everything
Speaker 1: as particles and they pull on pushing each other by
Speaker 1: passing other particles between them, or you can think of
Speaker 1: just fields and energy is flowing between the fields. And
Speaker 1: I think the field's picture is really helpful to think
Speaker 1: about for this question, because what we're talking about is
Speaker 1: not just one part of it's a particle interacting with
Speaker 1: another particle, right, Photons turning into electrons and back and forth.
Speaker 1: And in the field picture, that's kind of beautiful. What
Speaker 1: we see there is two fields interacting like a photon
Speaker 1: as it flies through the universe is not just a
Speaker 1: ripple in the electromagnetic field, as we say, because the
Speaker 1: electromagnetic field affects the electron field, and vice versa. So
Speaker 1: when you say in the particle picture, okay, a photon
Speaker 1: is flying along and you can turn into an electron
Speaker 1: and positron and go back in the field picture, that's
Speaker 1: the same thing as saying energy can slash from the
Speaker 1: photon field to the electron field and back. And what's
Speaker 1: really happening is not that there is an electron there
Speaker 1: or there is a photon there. But the thing we
Speaker 1: call a photon is this interaction between the two fields.
Speaker 1: So that's the problem with putting your finger on like
Speaker 1: is it the same photon? Well, what do you mean
Speaker 1: by a photon? Do you mean just the electromagnetic field,
Speaker 1: like theoretically pure concept, or do you mean the thing
Speaker 1: we see in the universe, which is like buzzing interaction
Speaker 1: between photons and electrons or the photon and electron fields.
Speaker 1: That's really what a photon is. A photon that hits
Speaker 1: your eye from Andromeda has interacted with the electron field
Speaker 1: all the way between there and here.
Speaker 2: Okay, can we give a two sentence answer to summarize.
Speaker 1: Yeah, So what is a photon? A photon, I think
Speaker 1: is all the possible things that could happen between A
Speaker 1: and B, and when the photon is created and the
Speaker 1: photon is observed, you can't really dig into what happens
Speaker 1: in between because there are multiple possibilities and all of
Speaker 1: them play a role. Right. So now, so Kevin's question,
Speaker 1: what do we mean by the same photon? Well, you know,
Speaker 1: I think that you can't really think about those individual
Speaker 1: photons and say is it the same? And if you tried,
Speaker 1: you get yourself into all sorts of other hairy misses
Speaker 1: that we touched on earlier, Like think about an individual
Speaker 1: photon not just flying through space, but like bouncing off
Speaker 1: of a mirror. What happens when a photon bounces off
Speaker 1: of a mirror, Well, we think it's absorbed and re
Speaker 1: emitted at the right angle. Is that the same photon? Well,
Speaker 1: you know, it's like if you shine a light in
Speaker 1: the mirror, the light hits your eyes. We think of
Speaker 1: the light as bouncing off and hitting your eyes, but
Speaker 1: it's been reabsorbed and re emitted. Is that the same?
Speaker 1: If you say that's not the same, that means that
Speaker 1: every time particles interact, they're no longer the same particle.
Speaker 1: But particles are interacting constantly all the time. You are
Speaker 1: a huge pile of particles interacting, which means that you
Speaker 1: were not the same you were a millisecond ago. So
Speaker 1: that leads nowhere. If you say that particle interaction means
Speaker 1: they're not the same particle anymore, then you have no
Speaker 1: useful meaning for the word same. Then you have to say, well,
Speaker 1: then maybe a particle is the same if it's like
Speaker 1: mostly unchanged. You shot the photon at the wall, it
Speaker 1: bounced off, and it's mostly the same energy and the
Speaker 1: same frequency and all that kind of stuff. So it's
Speaker 1: mostly the same photon even though it's interacted. So from
Speaker 1: that point of view, then the answer to Kevin's question
Speaker 1: would be like, yeah, it's the same photon. And I
Speaker 1: think philosophically unpeeling it. It's a big blob of energy.
Speaker 1: It's flowing through the universe. It's oscillating between the different fields.
Speaker 1: It doesn't really matter. That has a chance to be
Speaker 1: an electron here and a chance to be a photon there.
Speaker 1: It's the same blob of energy that was sent to
Speaker 1: you from Andromeda. So I think it's the same photon.
Speaker 1: So does that make sense to you, Kelly? What do
Speaker 1: you think.
Speaker 2: Yes, all right, that makes sense to me. Here, let
Speaker 2: me see if I can explain it.
Speaker 3: Okay.
Speaker 2: So the reason that it's a complicated question is because
Speaker 2: it's hard to think of a particle as like a
Speaker 2: point in space. They're like packets of energy that are
Speaker 2: interacting with other packets of energy, and they can be
Speaker 2: hard to describe.
Speaker 3: You know, they're.
Speaker 2: Interacting like they're a wave, like they're a string, but
Speaker 2: they're just sort of things that are interacting with other things,
Speaker 2: and that's what they're doing all the time. And so
Speaker 2: to try to figure out is this the exact same
Speaker 2: thing when part of how we understand it is that
Speaker 2: these things are changing and interacting over.
Speaker 1: Time, it makes it an awkward question.
Speaker 3: Yeah, yeah, is that an okay way to summarize it?
Speaker 1: Yeah, I think that's great. I'm giving you a PhD
Speaker 1: in Internet physics right now?
Speaker 2: Yes, right, okay, but grades are really important to me,
Speaker 2: and I haven't gotten one in like fifteen years, So
Speaker 2: can you tell me?
Speaker 3: And I got an A. Actually I kind of feel
Speaker 3: like that was more like a B answer.
Speaker 1: No, that was a solid A answer. Yeah, And now
Speaker 1: I'm curious what Kevin thinks about our answer. So in
Speaker 1: a moment, you'll hear Kevin giving us a grade on
Speaker 1: our physics answers to his philosophy question.
Speaker 7: Hi Janyan Kelly, thank you for answering my question. I
Speaker 7: think you mean that a photon is quantum mechanical, so
Speaker 7: it's a mix of the probabilities of all the possible
Speaker 7: things that can happen. Also, depending on the meaning of saying,
Speaker 7: the photon is the same and not the same at
Speaker 7: the same time, which is mind boggling. I totally love
Speaker 7: these kinds of answers.
Speaker 2: Thank you so much to Chris, Margie and Kevin for
Speaker 2: their amazing questions today. We had so much fun thinking
Speaker 2: about these problems. And if you have a question that
Speaker 2: you would like to share with us, please write us
Speaker 2: at questions at Daniel and Kelly dot org.
Speaker 3: We would love to hear from you.
Speaker 1: We would and your friends will be so impressed to
Speaker 1: hear your voice on a podcast, especially a nerdy podcast
Speaker 1: like ours.
Speaker 3: Huzza.
Speaker 1: Thanks everyone, keep asking questions and stay curious.
Speaker 3: See you later.
Speaker 2: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.
Speaker 3: We would love to hear from you, We really would.
Speaker 1: We want to know what questions you have about this
Speaker 1: extraordinary universe.
Speaker 2: We want to know your thoughts on recent shows, suggestions
Speaker 2: for future shows.
Speaker 3: If you contact us, we will get back to you.
Speaker 1: We really mean it. We answer every message. Email us
Speaker 1: at Questions at Danielankelly dot org, or.
Speaker 3: You can find us on social media.
Speaker 2: We have accounts on x, Instagram, Blue Sky and on
Speaker 2: all of those platforms.
Speaker 3: You can find us at d and kuniverse.
Speaker 1: Don't be shy right to us