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