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Speaker 1: Hey, Daniel, what do you think will happen the day

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Speaker 1: we discover alien life? Oh? I'm imagining like a huge

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Speaker 1: worldwide celebration. Oh yeah, and you think it'll be good news. Yeah,

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Speaker 1: I think we'll learn something very deep and important about

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Speaker 1: the nature of life and the universe and everything. But

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Speaker 1: what if it's not good news? What do you considered

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Speaker 1: darker possibilities about alien life? Like if they're not friendly

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Speaker 1: to humans they show up in space and zappaus, Well,

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Speaker 1: they could be friendly to humans. You know, they might

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Speaker 1: find us delicious. I guess that depends on which kind

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Speaker 1: of humans they find delicious. We probably all taste the same,

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Speaker 1: you know, like chicken. Maybe chickens taste like humans. I'm

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Speaker 1: sure there are people in this world who know the

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Speaker 1: answer to that question. What if we find out about

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Speaker 1: aliens because of some giant space battle they're having with themselves.

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Speaker 1: Oh well, that sounds pretty exciting. In that case, I'd

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Speaker 1: like to reserve a front row seat. Well really, Oh

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Speaker 1: you do that, I'll be running away in the other direction,

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Speaker 1: and I'll be popping the popcorn. Hi, am Orham and

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Speaker 1: cartoonists and the creator of PhD comments. Hi, I'm Daniel

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Speaker 1: I'm a particle physicist and a professor at UC Irvine,

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Speaker 1: and I don't wish any aliens to die, but I

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Speaker 1: do want to see a giant alien space battle. Wait,

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Speaker 1: so how would they have a battle but without any

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Speaker 1: even dying. Isn't just like a virtual battle or they're

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Speaker 1: like plane laser tag? What are you talking about here?

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Speaker 1: I mean it's like a wortal battle. Are they having

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Speaker 1: a wortal battle? Maybe they've evolved to a higher plane

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Speaker 1: of combat exactly. No, it's tension within me. As much

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Speaker 1: as I would like to see alien space battles, I

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Speaker 1: also don't want any aliens out there to die. But

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Speaker 1: you know some of our favorite stories are about alien

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Speaker 1: space battles. Isn't that what Star Wars is all about.

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Speaker 1: Star Wars is about aliens. That's what you told me.

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Speaker 1: It's in another galaxy, far far away, right, they're all aliens.

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Speaker 1: Maybe we're the aliens in the Star Wars universe. Well,

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Speaker 1: we're not capable of putting on giant space battles yet. Also,

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Speaker 1: people don't die in Star Wars. They just come back

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Speaker 1: as ghosts, Jedi ghosts more powerful than you could even imagine,

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Speaker 1: Or do you the Emperor did they just keep bringing

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Speaker 1: you back for all the movies. Don't the Stormtrooper die though,

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Speaker 1: or do they also come back as Jedi ghosts. I

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Speaker 1: guess it's not clear. You know, they get zapped with

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Speaker 1: their little armor and they just fall down. Maybe they're

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Speaker 1: just taking a nap. There you go. I'd like a

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Speaker 1: giant alien space battle where the losers just take a nap. Yeah,

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Speaker 1: I want to see that movie. Star naps were Welcome

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Speaker 1: to our podcast Daniel and Jorge Explain the Universe, a

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Speaker 1: production of iHeartRadio, in which we try to zap your

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Speaker 1: brain with all sorts of incredible information about the universe.

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Speaker 1: We know that everything out there is amazing and mysterious

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Speaker 1: and confusing, but we hope to help you understand what

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Speaker 1: little of it human entity has managed to decode. And

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Speaker 1: we hope that one day aliens come and give us

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Speaker 1: a little bit more information about what's going on out

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Speaker 1: there in the universe, if indeed they do exist. That's right,

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Speaker 1: because it is a pretty incredible universe, and we do

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Speaker 1: battle every day here with the mysteries of it, and

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Speaker 1: we go to war with our ignorance about how it

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Speaker 1: works and what's going on in the universe. We're trying

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Speaker 1: to drop a knowledge bomb on everybody's ignorance. That's right.

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Speaker 1: You can think of us as a laser gun of

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Speaker 1: amazing facts zapping people's brains. There's that warm, fuzzy feeling

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Speaker 1: you get when you understand something about the universe. But

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Speaker 1: there's also lots of things that we still don't understand

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Speaker 1: about the universe, things that give you that gnawing feeling

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Speaker 1: of desperate curiosity, that desire to just know what's going

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Speaker 1: on out there. There's some of the deepest questions in

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Speaker 1: human existence which have answers, which are facts about the

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Speaker 1: universe which maybe one day people will know. How frustrating

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Speaker 1: is it to live in the era of dark to

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Speaker 1: not know the answers to basic questions like are we

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Speaker 1: alone in the universe? Yeah? What bigger question can there

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Speaker 1: be about the existence of humans than the question of

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Speaker 1: whether we are the only living thing or intelligent thing

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Speaker 1: living and existing in this universe? And we wonder about it,

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Speaker 1: we speculate about it, but we have a very very

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Speaker 1: deep lack of information about it. The universe is vast,

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Speaker 1: and from our tiny little rock we have done a

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Speaker 1: pretty good job of exploring a tiny, little corner of it.

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Speaker 1: We have telescopes to tell us about nearby star systems

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Speaker 1: and compeer further and deeper into the universe, but we've

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Speaker 1: only begun recently to identify other planets and other places

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Speaker 1: in the universe where life might spring independently from Earth. Yeah,

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Speaker 1: we know that here in our Solar systems there aren't

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Speaker 1: on at the signs of life, and so we know

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Speaker 1: that if there is alien life out there, it has

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Speaker 1: to be kind of far away. Right, how close is

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Speaker 1: the nearest planet to us light years away? The nearest

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Speaker 1: planet to me is about zero meters away. It's right

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Speaker 1: here under my feet. There are other places in the

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Speaker 1: Solar System people think there might be life, like under

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Speaker 1: the frozen crust of Europa. So there are still exciting

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Speaker 1: places in our backyard. But you're right, other Solar systems

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Speaker 1: are frustratingly far away, several light years. The closest identified

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Speaker 1: exoplanets around Proxima Centauri, which happens to be their closest star,

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Speaker 1: just under four light years away. And what that tells

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Speaker 1: us is that there are planets everywhere in the galaxy

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Speaker 1: and in the universe. We now think that almost every

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Speaker 1: star out there has planets around it, and a huge

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Speaker 1: fraction of them have even earthlike planets, maybe around this size,

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Speaker 1: maybe around this kind of surface temperature, maybe even with

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Speaker 1: liquid water on their surface. And so with so many

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Speaker 1: places that life could be out there in the universe,

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Speaker 1: sometimes we wonder, why haven't we found it already. Yeah,

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Speaker 1: it's a very big question, one that would kind of

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Speaker 1: determine our place in the universe. Because if the answer

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Speaker 1: is that there isn't life out there, that is that

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Speaker 1: humans are pretty special right in the entire universe. Imagine

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Speaker 1: what it'd be like to know that we're the only

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Speaker 1: intelligence species in such a big place. Yeah, it would

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Speaker 1: make you feel special. It'll also make you feel kind

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Speaker 1: of lonely being the only intelligent life in the entire universe.

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Speaker 1: It's kind of a lot of responsibility also, like we're

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Speaker 1: the only ones out there doing anythinking. We're the only

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Speaker 1: ones trying to figure out this huge puzzle about the

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Speaker 1: nature of the universe, trying to crack the cosmic mystery

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Speaker 1: of how all these quantum particles weave themselves together into

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Speaker 1: this experience. I prefer to imagine that there's lots of

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Speaker 1: other civilizations out there, and maybe they've even solved some

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Speaker 1: of these questions and have the answers waiting for us.

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Speaker 1: But we don't know. And we've been looking out in

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Speaker 1: the cosmos and listening for signals from aliens, hoping that

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Speaker 1: they are as excited as we are to meet their neighbors,

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Speaker 1: and sending us messages which we might capture in radio

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Speaker 1: waves or other electromagnetic signals. Of course, so far we've

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Speaker 1: heard nothing conclusive. Wait, so you want aliens to exist

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Speaker 1: just to take some of the pressure off of your job.

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Speaker 1: Is that kind of what you're you're talking about? You know,

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Speaker 1: I'm very strongly believe in funding basic research and expanding science,

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Speaker 1: and that goes beyond the limits of our species. I

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Speaker 1: think science should be funded here on Earth and everywhere

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Speaker 1: in the universe, and I hope that budget aliens out

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Speaker 1: there are, you know, giving a healthy dose of funding

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Speaker 1: to those science aliens out there struggling to understand the

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Speaker 1: nature of the universe, burned by the same curiosity that

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Speaker 1: we have. Or maybe they don't. Maybe they just don't

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Speaker 1: care about the nature of the universe and they're not

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Speaker 1: even doing science. I feel like you're like little kid

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Speaker 1: in class who's looking at his test or her tests

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Speaker 1: and going like, I have no idea what's going on,

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Speaker 1: and you're sort of like looking around to see if

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Speaker 1: anyone else knows the answers. Yes, I definitely want to

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Speaker 1: cheat off of alien physicists. I would love to get

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Speaker 1: like an alien physics textbook and then win like a

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Speaker 1: whole string of Nobel prizes here on Earth just by

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Speaker 1: copying their ideas. Yes, I will completely admit that is

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Speaker 1: my fantasy. Really, So wait, you would get the secrets

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Speaker 1: from the alien I'm just trying to figure this scenario.

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Speaker 1: Let's work through it. You would get the secrets from

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Speaker 1: the aliens, but you wouldn't tell anyone that aliens exist,

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Speaker 1: and you would use that knowledge for your own personal game.

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Speaker 1: That sounds fantastic. Yes, remind me not to tell you

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Speaker 1: any secrets. Then, If you are holding a Nobel prize

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Speaker 1: winning secret, please do share it with me. I would

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Speaker 1: love to hear it. You would be the last person

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Speaker 1: I would share with, obviously. I hope you would share

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Speaker 1: it with all of humanity, Like if somebody gave me

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Speaker 1: secrets from aliens, I would share it with all of

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Speaker 1: humanity absolutely, But the aliens themselves would be the biggest secrets.

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Speaker 1: I just said it's the biggest question in human existence. No,

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Speaker 1: you're right, And of course, if aliens do come or

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Speaker 1: communicate with us, probably physicists wouldn't be at the front

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Speaker 1: of the line of people who get to chat with them, right,

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Speaker 1: probably would send like engineers or doctors, or politicians or

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Speaker 1: linguists or mathematicians or philosophers before the physicists even get

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Speaker 1: their shot. I think I would send the physicists first

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Speaker 1: for sure. Yeah, because you know what, if they're hungry,

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Speaker 1: we got to test the waters here. So you don't

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Speaker 1: want me to learn the secrets from the aliens, but

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Speaker 1: you do want me to be there first. I mean,

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Speaker 1: there's two sides to that coin. Well, I want you

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Speaker 1: to learn the secrets, but I want you to share

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Speaker 1: the secrets verybody. I will share the secrets with you

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Speaker 1: and the Nobel Committee. And if their secret is what

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Speaker 1: their stomachs look like, well, you know you can't share it,

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Speaker 1: but at least we would know. Just like going inside

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Speaker 1: a black hole, you learn some deep secrets about the universe,

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Speaker 1: but only you can know them. But it's interesting you

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Speaker 1: talk about some of the ways that people usually think

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Speaker 1: that we're gonna meet aliens or know about aliens, which

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Speaker 1: is getting signals from them. I mean that's sort of

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Speaker 1: like one way we can learn about them. I guess

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Speaker 1: another way is to go to another planet and see

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Speaker 1: them too, right, Yeah, And this is a really common

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Speaker 1: thing in science. When you have no idea how hard

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Speaker 1: a problem is, you start with the easiest things, like

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Speaker 1: maybe the universe is filled with aliens and they're all

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Speaker 1: sending messages and we just haven't been listening, and as

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Speaker 1: soon as we turn on our electronic ears and use

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Speaker 1: our radio satellites to tune in, maybe we could instantly

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Speaker 1: tap into the galactic internet and hear all those conversations.

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Speaker 1: There's some scenario in which it would have been easy,

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Speaker 1: and as soon as we started listening, we discovered it.

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Speaker 1: So it makes sense to first do the easy thing

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Speaker 1: and see if alien messages our feeling space. Of course,

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Speaker 1: we've been listening and we haven't heard anything, and so

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Speaker 1: people are starting to try to be creative and think about, like, well,

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Speaker 1: what are other ways we could hear from aliens, or

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Speaker 1: what are other ways we could detect their existence? As

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Speaker 1: you say, maybe we could go to those planets and

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Speaker 1: discover them. Right. That's limited, of course, by our ability

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Speaker 1: to travel from star to star. These stars are so

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Speaker 1: far away and the speed of light is such a

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Speaker 1: stubborn limitation. But until we develop a warp drives or

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Speaker 1: practical wormholes, it's not realistic to think that we could

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Speaker 1: explore a significant fraction of the galaxy. Yeah, Like, what

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Speaker 1: would it take, I guess to send a probe to

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Speaker 1: Alpha Centauri? Right, it's four light years away. That's like

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Speaker 1: zillions of miles away. Right now, it seems kind of

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Speaker 1: impossible because I think the furthest we've send a probe

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Speaker 1: right now is just barely outside this Solar system, right,

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Speaker 1: and it took like thirty years, yes, exactly, the most

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Speaker 1: distant object send by humanity. Some of these old Voyager

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Speaker 1: and Pioneer probes are not very far outside the Solar system,

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Speaker 1: so it would take a long time for anything to

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Speaker 1: get anywhere. But you know, if you were thinking about

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Speaker 1: it on long time scales, it's not going to take

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Speaker 1: like millions of years. We're talking like thousands or tens

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Speaker 1: of thousands of years. And if you send a few

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Speaker 1: probes to other planets, and if those probes are very clever,

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Speaker 1: they're like AI driven self replicating probes, so they can

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Speaker 1: land on some distant moon, they can find materials on

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Speaker 1: those moons to make more of themselves, and then they

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Speaker 1: can send those probes out, and those probes make more

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Speaker 1: of themselves, and those make more of themselves. It's not

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Speaker 1: impossible to imagine rapidly exploring the entire galaxy, where by

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Speaker 1: rapid we mean on the time scale of like fifty

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Speaker 1: to one hundred thousand years. So that's a really interesting

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Speaker 1: argument because it suggests that with technology not super far

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Speaker 1: in our future, some other civilization could have explored the

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Speaker 1: whole galaxy with self replicating probes. And then you have

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Speaker 1: to ask, like, well, why haven't we been visited by

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Speaker 1: such a probe yet? Are there no other advanced civilizations

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Speaker 1: out there who have this idea? Yeah, we address this

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Speaker 1: question and this whole scenario in our book. Frequently asked

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Speaker 1: questions about the universe. That was one of the chapters,

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Speaker 1: right like why haven't we seen aliens? And maybe we

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Speaker 1: can do that with these self repulating robots, which would

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Speaker 1: litter the universe in no time exactly. And one basic

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Speaker 1: assumptions a lot of these scenarios make is that aliens

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Speaker 1: want us to find them, or that they are trying

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Speaker 1: to talk to us, or they are curious about the

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Speaker 1: rest of the universe as well, so they're sending messages

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Speaker 1: out or they're sending probes out there explorational the same

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Speaker 1: way that we are. But of course we don't know

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Speaker 1: what alien psychology is like, and what does aliens want,

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Speaker 1: or even what it means to want something as an alien.

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Speaker 1: So these days a lot of people are imagining other

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Speaker 1: ways to detect aliens when they're not trying to be detected.

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Speaker 1: Are there things the aliens can do imprints they leave

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Speaker 1: on the universe that aren't intended for us to discover them,

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Speaker 1: but might allow us to spot them anyway. So today

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Speaker 1: on the program, we'll be asking the question could we

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Speaker 1: detect alien nuclear explosions? I imagine you're saying these are

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Speaker 1: like accidental nuclear explosions or on purpose nuclear explosions, either one, right,

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Speaker 1: we don't discriminate. We just like to know the aliens

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Speaker 1: are there, and whatever they do in their normal civilization extrapolasition,

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Speaker 1: we'd like to see if we could detect it. Maybe

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Speaker 1: they're just doing testing like we're doing, or maybe they

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Speaker 1: have some globe spanning nuclear annihilation. The question is, could

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Speaker 1: we see it right, If aliens are blowing up nuclear bombs,

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Speaker 1: is it possible for us to spot that? Yeah, because

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Speaker 1: as you mentioned, you know, one scenario is that they're

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Speaker 1: sending out signals on purpose, either to talk to us

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Speaker 1: directly or just like that's their TV, maybe their broadcast TV.

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Speaker 1: But I think we talked in an earlier episode about

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Speaker 1: how like for us to detect the signal from an alien,

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Speaker 1: it would have to be like a pretty focus beam, right,

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Speaker 1: like the like the club we're just listening to their

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Speaker 1: TV broadcast is pretty low, that's right. If you're just

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Speaker 1: sending signals in every direction, then you pay a really

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Speaker 1: big price because those signals get weaker with distance, and

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Speaker 1: they get weaker with distance squared. So when signals go

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Speaker 1: twice as far, they're four times as week, When they

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Speaker 1: go ten times as far, they're one hundred times as week.

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Speaker 1: That makes it really really hard to detect non focus signals.

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Speaker 1: And if we wanted to detect signals that we could

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Speaker 1: generate using technology that we have, we would not be

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Speaker 1: able to spot signals of the kinds we can generate

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Speaker 1: using our own technology from planets that are more than

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Speaker 1: like one light year away. If however, they're like beaming

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Speaker 1: us messages, they're shooting laser beams in our direction. Then

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Speaker 1: the math works differently and we could get messages from

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Speaker 1: further away, But then they'd have to know we were

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Speaker 1: here and try to send us messages on purpose, which

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Speaker 1: seems less likely. I think here today we're exploring a

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Speaker 1: different scenario, which is like, what if they're doing something

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Speaker 1: without trying by accident maybe or through some sort of event,

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Speaker 1: and then that's what we see, and that's how we

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Speaker 1: know that there are aliens exactly. And people have been

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Speaker 1: thinking about this and wondering like, well, what's the most

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Speaker 1: visible thing that you can do, not just broadcasting Rick

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Speaker 1: and Morty episodes into the cosmos? All right, Sometimes our

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Speaker 1: civilization does things which generate very bright flashes of radiation,

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Speaker 1: and hey, what's brighter than a nuclear explosion? But what

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Speaker 1: if there's a kid in that alien planet pointing a

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Speaker 1: laser partner directly Ow my eye? Ow alien burnt my eye? Yeah,

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Speaker 1: I know, that's why you should be careful you knock

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Speaker 1: about this guy. So then the scenario here is that

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Speaker 1: somehow this alien civilization out there is exploding nuclear their

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Speaker 1: own nuclear bombs, either by accident, or some testing or something.

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Speaker 1: Maybe they have their own nuclear war, and so the

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Speaker 1: question is like, could we see those nuclear explosions exactly?

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Speaker 1: All right? Well, as usual, we were wondering how many

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Speaker 1: people out there had the interesting curiosity to ask this

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Speaker 1: question about alien life and how we could detect them. So,

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Speaker 1: as usual, Daniel went out there. Did you go to

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Speaker 1: the internet or are you? Are you going on campus?

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Speaker 1: Now these are still Internet based questions. I felt a

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Speaker 1: little bit weird walking around campus asking people about aliens

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Speaker 1: and nuclear bombs. That's never stopped you before. I thought

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Speaker 1: it might get reported to the UCI police. Yeah, you

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Speaker 1: have tenure. They're not gonna fire you. Anyways, usually have

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Speaker 1: to do worst things. So thanks very much to our

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Speaker 1: internet volunteers who responded with enthusiasm to this question. If

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Speaker 1: you would like to play this part in future episodes,

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Speaker 1: please write to me to questions at Daniel and Jorge

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Speaker 1: dot com. We can do it all over email. It's fast,

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Speaker 1: it's easy, it's fun to think about it for a second.

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Speaker 1: Do you think we could detect alien nuclear explosions? Here's

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Speaker 1: what people have to say. Yes, So it depends whether

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Speaker 1: the detonation happened on Earth or a planet from Solar

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Speaker 1: System or somewhere far away. In any of these cases,

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Speaker 1: I think we might be able to detect. Considering that

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Speaker 1: why decaying of the matter and the amount of radiation

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Speaker 1: that is being exposed out of that location on Earth,

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Speaker 1: we might be able to analyze whether it's man made

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Speaker 1: or alien, and if it is happening on some other planet.

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Speaker 1: Considering the amount of information that we have already gained

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Speaker 1: with the telescopes in place, we will be able to

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Speaker 1: do it. That's what I believe. By now, we have

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Speaker 1: satellites now that can detect detonations on Earth. I don't

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Speaker 1: think it would work at interstellar distances, especially considering that

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Speaker 1: there's so many sources of radiation in space, you know,

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Speaker 1: from stars to gamma ray burst everything in between. So no,

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Speaker 1: I don't think we could. Well, I guess so. I

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Speaker 1: guess it would depend on how good the detector was

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Speaker 1: and how far away it was away from you. If

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Speaker 1: there was set off over your head, you might be

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Speaker 1: able to detect it pretty soon. I feel like we

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Speaker 1: probably could detect alien nuclear detonations if there was like

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Speaker 1: enough radiation to reach far enough, But other than that,

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Speaker 1: I don't really think we could all right. Some people

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Speaker 1: said yes, some people said no, some people said maybe yeah.

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Speaker 1: I think they really put their finger on the issue,

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Speaker 1: which is that nobody knows, not even us. It's all

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Speaker 1: about brightness and distance. You know, what's the faintest radiation

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Speaker 1: we could pick up? And how close would these bombs

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Speaker 1: have to be for us to spot them. I feel

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Speaker 1: like you're missing one important factor, which is how big

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Speaker 1: are these bombs? That's a huge unknown. You're right, and

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Speaker 1: we'll get into it in a minute. And the only

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Speaker 1: standard we have is like how big are our bombs?

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Speaker 1: So we can imagine whether we could detect nuclear explosions

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Speaker 1: of the size we could make if aliens also did them.

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Speaker 1: All right, we'll dig into it, but I guess first

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Speaker 1: let's start with the basics, Like Daniel, what happens during

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Speaker 1: a nuclear explosion? Besides the explosion part of it. Yeah,

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Speaker 1: to understand whether we could see a nuclear explosion on

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Speaker 1: another planet, you have to think about what the signals are,

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Speaker 1: like what signals does a nuclear explosion generate? And we

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Speaker 1: had a whole episode about how nuclear bombs work where

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Speaker 1: we went to a lot of detail, but not enough

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Speaker 1: detail for you to build a nuclear bomb. Hopefully but

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Speaker 1: human nuclear weapons at least are either fission weapons or

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Speaker 1: fusion weapons triggered by fission. And remember that the basic

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Speaker 1: processes here fission involved breaking up of a heavy nucleus

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Speaker 1: like plutonium or uranium, which then shoots off a bunch

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Speaker 1: of neutrons and rams into other nuclei, which breaks them

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Speaker 1: apart and sets off a chain reaction where you very

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Speaker 1: rapidly are releasing energy. And the fusion bomb is similar

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Speaker 1: except it uses a fission bomb to compress a bunch

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Speaker 1: of fusion fuel that it fuses, and in both scenarios

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Speaker 1: the key thing is releasing a huge amount of energy

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Speaker 1: very very quickly, but not just energy, right, You're releasing

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Speaker 1: energy but also a lot of radiation. Yeah, maybe step

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Speaker 1: us through like what's actually being released, Like when you

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Speaker 1: fuse things together they click together, to nuclear click together,

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Speaker 1: and then what actually gets released like light or particles

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Speaker 1: or Yeah, so fusion produces high energy photons. It also

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Speaker 1: produces neutrons and electrons and neutrinos. Right, so all these

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Speaker 1: kinds of things are produced and then much just produced,

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Speaker 1: but they're like they're produced, but then they're flying really fast. Yes,

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Speaker 1: they're produced, and they're carrying a lot of energy is

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Speaker 1: what you actually see from the bomb from like a

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Speaker 1: certain distance. Depends on how that energy is absorbed or

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Speaker 1: not absorbed. So, for example, a lot of the energy

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Speaker 1: gets dumped into the matters immediately surrounding the bomb, right,

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Speaker 1: and so it's absorbed very very rapidly by the st

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Speaker 1: around the bomb, which expands that matter and creates a

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Speaker 1: shock wave. I mean like the bomb casing or like whatever,

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Speaker 1: if it's on the ground, that that's what it's going

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Speaker 1: to push out. Yeah, I mean whatever material is around

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Speaker 1: the bomb, like the air or the water or the ground,

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Speaker 1: and you get very different scenarios if you have an

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Speaker 1: in air explosion or underground explosion or just above the water.

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Speaker 1: But the material that surrounds the bomb is inundated with

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Speaker 1: a huge amount of energy, a lot of it from

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Speaker 1: gamma rays, and a lot of that gets rapidly absorbed

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Speaker 1: and that material gets heated up to like tens of

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Speaker 1: millions of degrees and then you get this shockwave. So

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Speaker 1: in the end, on average, and it depends on exactly

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Speaker 1: what you've surrounded the bomb with, about half of the

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Speaker 1: energy of a nuclear bomb go these shockwaves, these expanding

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Speaker 1: waves of matter basically sound waves through matter that carry

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Speaker 1: away a lot of this energy, doesn't It depend on

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Speaker 1: what's around the bomb. Like if you explode it in water,

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Speaker 1: all of it's going to go into the water, But

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Speaker 1: if you put it in air, you know there's maybe

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Speaker 1: a chance for that energy to go out further. Even

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Speaker 1: in air, a lot of that energy is absorbed by

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Speaker 1: the air and you get shock waves. So yes, it

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Speaker 1: definitely does depend on the kind of material surrounded. Like

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Speaker 1: if you blow it up underground, it's absorbed differently than

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Speaker 1: if you blow it up in the air. But you know,

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Speaker 1: since we're just dealing with like approximate numbers here, roughly

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Speaker 1: on average, over all those circumstances, about half of the

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Speaker 1: energy gets dumped into shock waves and then like another

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Speaker 1: forty percent of the energy comes out in what we

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Speaker 1: call thermal radiation, basically photons to which the atmosphere is

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Speaker 1: transparent visible light, infrared light, UV light, things that are

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Speaker 1: not immediately absorbed by the surrounding material which conduct fly

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Speaker 1: out through that material because that material is transparent to

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Speaker 1: this kind of radiation. Why is it transparent. Is it

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Speaker 1: because it just doesn't absorb because of quantum effects, or

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Speaker 1: is it just that it's so like air is so

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Speaker 1: thin that it just doesn't hit enough air molecules. Yeah,

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Speaker 1: air is transparent to visible light, right, we know that

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Speaker 1: because we can see the sun through the air. Why

431
00:23:01,160 --> 00:23:03,320
Speaker 1: is the air transparent to visible light, You're right, is

432
00:23:03,400 --> 00:23:07,320
Speaker 1: quantum effects. You have certain gases under certain conditions, and

433
00:23:07,400 --> 00:23:10,520
Speaker 1: they either like to absorb photons of various frequencies or

434
00:23:10,560 --> 00:23:13,680
Speaker 1: they don't. These air molecules can't just absorb a photon

435
00:23:13,720 --> 00:23:16,480
Speaker 1: of an arbitrary frequency. They have to have like a

436
00:23:16,600 --> 00:23:20,399
Speaker 1: quantum state that their electron can jump up into, or

437
00:23:20,400 --> 00:23:22,880
Speaker 1: like a new rotation that they can do. So atoms

438
00:23:22,880 --> 00:23:26,280
Speaker 1: can only absorb certain frequencies of light, and the other

439
00:23:26,320 --> 00:23:29,840
Speaker 1: frequencies pass right through. So air is mostly transparent to

440
00:23:30,040 --> 00:23:33,679
Speaker 1: visible light and also infrared light. It's less transparent in

441
00:23:33,720 --> 00:23:35,800
Speaker 1: the UV, which is one reason why we have like

442
00:23:36,280 --> 00:23:39,879
Speaker 1: UV space telescopes above the atmosphere. But you know a

443
00:23:39,960 --> 00:23:42,439
Speaker 1: lot of energy is dumped out and so some of

444
00:23:42,440 --> 00:23:47,080
Speaker 1: these very high energy UV light does survive passing through

445
00:23:47,080 --> 00:23:49,560
Speaker 1: the atmosphere. If you're near a nuclear bomb, so you

446
00:23:49,560 --> 00:23:52,359
Speaker 1: have like fifty percent of it roughly in the shock wave,

447
00:23:52,520 --> 00:23:56,960
Speaker 1: like another forty percent in thermal radiation these photons that

448
00:23:57,040 --> 00:24:00,440
Speaker 1: don't get absorbed, and then another ten percent in other

449
00:24:00,480 --> 00:24:04,000
Speaker 1: particles like neutrons or very high energy photons we call

450
00:24:04,080 --> 00:24:07,800
Speaker 1: gamma rays or electrons. Is it sort of like lightning

451
00:24:07,800 --> 00:24:09,960
Speaker 1: and thunder? Like you will see the flash of a

452
00:24:10,080 --> 00:24:14,560
Speaker 1: nuclear bomb before you actually get hit by the shockwave. Yeah,

453
00:24:14,600 --> 00:24:17,399
Speaker 1: it's really cool. You actually see two flashes of a

454
00:24:17,480 --> 00:24:21,359
Speaker 1: nuclear bomb. You see the first flash because the visible

455
00:24:21,440 --> 00:24:23,960
Speaker 1: light reaches you before the shockwave. But at some point

456
00:24:23,960 --> 00:24:27,320
Speaker 1: the shock wave passes the fireball because the shockwave is

457
00:24:27,520 --> 00:24:31,800
Speaker 1: making the material more dense, which acts to obscure the fireball.

458
00:24:32,280 --> 00:24:35,800
Speaker 1: So the shockwave itself is opaque to the kind of

459
00:24:35,880 --> 00:24:38,840
Speaker 1: light being generated by the nuclear bomb. So then for

460
00:24:38,880 --> 00:24:41,000
Speaker 1: a moment you can't see the fireball, but then it

461
00:24:41,040 --> 00:24:43,560
Speaker 1: dissipates and you can see it again. So it's like

462
00:24:43,600 --> 00:24:45,960
Speaker 1: you see fireball and then you see the shock wave,

463
00:24:46,000 --> 00:24:47,639
Speaker 1: and then you see the fireball. So it's sort of

464
00:24:47,680 --> 00:24:50,680
Speaker 1: like lightning and then thunder and then a second flash

465
00:24:50,720 --> 00:24:53,840
Speaker 1: of lightning. Whoa, I mean, assuming you survived the first

466
00:24:54,600 --> 00:24:57,720
Speaker 1: event to get to see the other two. Yeah, So

467
00:24:57,800 --> 00:25:00,679
Speaker 1: this is a very characteristic signature of nuclear bombs. This

468
00:25:00,920 --> 00:25:05,200
Speaker 1: double peak of gamma radiation over several milliseconds. Well, it's

469
00:25:05,200 --> 00:25:08,560
Speaker 1: definitely an event and nuclear explosion. And so the question

470
00:25:08,680 --> 00:25:12,960
Speaker 1: is if aliens exploded nuclear bombs in their planets, could

471
00:25:13,040 --> 00:25:16,639
Speaker 1: we see them from here. Let's dig into that question

472
00:25:16,840 --> 00:25:18,800
Speaker 1: and what we should be looking for if we're looking

473
00:25:18,840 --> 00:25:23,240
Speaker 1: for those kinds of signals. First, let's take a quick break.

474
00:25:36,040 --> 00:25:40,959
Speaker 1: All right, we are spending today imagining aliens blowing themselves up.

475
00:25:41,000 --> 00:25:44,080
Speaker 1: We're not hoping they blow themselves up, but if they do,

476
00:25:44,400 --> 00:25:47,280
Speaker 1: we hope to see it. We're not hoping they blow

477
00:25:47,320 --> 00:25:49,640
Speaker 1: themselves up, but if they do, it would be nice.

478
00:25:49,880 --> 00:25:52,080
Speaker 1: Is that what you say? Is that? What are you saying?

479
00:25:52,359 --> 00:25:56,840
Speaker 1: I mean, I don't aliens living in obscurity forever, or

480
00:25:56,920 --> 00:26:00,000
Speaker 1: aliens killing themselves about then we find out about them.

481
00:26:00,000 --> 00:26:01,760
Speaker 1: I mean, it would also be kind of sad to

482
00:26:01,840 --> 00:26:05,119
Speaker 1: discover aliens only to discover they had all killed themselves,

483
00:26:06,240 --> 00:26:08,439
Speaker 1: that they were the last ones. Yeah, that would be

484
00:26:08,600 --> 00:26:11,119
Speaker 1: that would be pretty tragic. Yeah, that would be a bummer. Well,

485
00:26:11,160 --> 00:26:14,119
Speaker 1: we've talked about what a nuclear explosion is and what

486
00:26:14,200 --> 00:26:16,320
Speaker 1: happens to it. So you said about half of the

487
00:26:16,520 --> 00:26:19,840
Speaker 1: energy is really just pushing the stuff around it so

488
00:26:19,920 --> 00:26:22,639
Speaker 1: I imagine that won't get very far. Maybe forty percent

489
00:26:22,680 --> 00:26:26,639
Speaker 1: of it goes into just light, basically invisible light or

490
00:26:26,760 --> 00:26:29,640
Speaker 1: light you'd be light, And about ten percent of it

491
00:26:29,680 --> 00:26:35,120
Speaker 1: goes into shooting out basically radiation, right, like charged particles. Yeah,

492
00:26:35,160 --> 00:26:39,800
Speaker 1: not just charged particles, but neutrons, gamma rays, and also electrons. Well,

493
00:26:39,800 --> 00:26:42,280
Speaker 1: gamma rays are light, right, Gamma rays are very high

494
00:26:42,400 --> 00:26:45,400
Speaker 1: energy photons, Yeah, even more high energy than X rays

495
00:26:45,560 --> 00:26:48,480
Speaker 1: or UV. These are all ionizing radiation. They all have

496
00:26:48,480 --> 00:26:52,600
Speaker 1: the capacity to knock electrons off of materials. And because

497
00:26:52,600 --> 00:26:56,200
Speaker 1: they're ionizing and electrons themselves have charge, they can also

498
00:26:56,280 --> 00:26:59,640
Speaker 1: generate an electro magnetic pulse. This is a common feature

499
00:27:00,080 --> 00:27:04,000
Speaker 1: a lot of movies nuclear weapons knocking out electronics because

500
00:27:04,040 --> 00:27:08,800
Speaker 1: of a very high energy pulse of electromagnetic radiation. Oh interesting,

501
00:27:08,920 --> 00:27:11,680
Speaker 1: it's not just that it's like a giant magnet. It's

502
00:27:11,720 --> 00:27:15,159
Speaker 1: like it's actually shooting out little magnets. Yeah, exactly. And

503
00:27:15,200 --> 00:27:17,760
Speaker 1: so all those gamma rays and all those electrons can

504
00:27:17,840 --> 00:27:20,520
Speaker 1: damage a lot of electronics. So if you have electronics

505
00:27:20,600 --> 00:27:23,280
Speaker 1: near a nuclear weapons blast, then you will feel it.

506
00:27:23,280 --> 00:27:26,640
Speaker 1: They could get knocked offline. They don't shoot protons explosions

507
00:27:26,760 --> 00:27:29,520
Speaker 1: or neutrinos. They do generate a lot of neutrinos. He

508
00:27:29,560 --> 00:27:33,080
Speaker 1: has absolutely fusion and fission both generate neutrinos, but not

509
00:27:33,119 --> 00:27:36,800
Speaker 1: so many protons. Mostly neutrons and neutrinos and electrons. What

510
00:27:36,880 --> 00:27:40,720
Speaker 1: about later rays and sound effects like in Star Wars?

511
00:27:40,960 --> 00:27:43,280
Speaker 1: They don't go pupupu as far as I've seen. It's

512
00:27:43,320 --> 00:27:46,000
Speaker 1: not in the literature. But the sounds of thousands of

513
00:27:47,200 --> 00:27:50,919
Speaker 1: souls being snuffed at the same time, Oh, that's sad.

514
00:27:51,040 --> 00:27:52,800
Speaker 1: I don't know if they create a great disturbance in

515
00:27:52,840 --> 00:27:54,960
Speaker 1: the force. We don't have detectors that can measure the

516
00:27:55,000 --> 00:27:57,840
Speaker 1: force yet, so I'm not sure about that, not yet

517
00:27:57,880 --> 00:28:00,000
Speaker 1: at least, although I have a good acronym for them.

518
00:28:00,080 --> 00:28:05,159
Speaker 1: They should be a named Jedi, right, And how does

519
00:28:05,200 --> 00:28:11,360
Speaker 1: that work? Just the Electron Detection Institute sounds good? Are

520
00:28:11,359 --> 00:28:13,199
Speaker 1: you setting that up with some funding? Are you going

521
00:28:13,240 --> 00:28:16,200
Speaker 1: to endow the Jedi Institute? Maybe I have already, I'm

522
00:28:16,200 --> 00:28:20,800
Speaker 1: just not telling you. No. That's extra frustrating. But you know,

523
00:28:20,880 --> 00:28:23,359
Speaker 1: there are a lot of scientists here on Earth that

524
00:28:23,400 --> 00:28:26,760
Speaker 1: are developed very sensitive technology for a studying nuclear weapons,

525
00:28:27,160 --> 00:28:30,280
Speaker 1: both because we want to understand what happens when they

526
00:28:30,320 --> 00:28:32,160
Speaker 1: blow up, because we have done tests and we want

527
00:28:32,200 --> 00:28:35,120
Speaker 1: to understand whether our nuclear weapons are working and are

528
00:28:35,160 --> 00:28:38,280
Speaker 1: still working and are surviving the test of time as

529
00:28:38,280 --> 00:28:41,040
Speaker 1: they sit in our stockpiles. But also because we wanted

530
00:28:41,040 --> 00:28:45,000
Speaker 1: to detect if other countries are blowing up their nuclear bombs.

531
00:28:45,040 --> 00:28:48,320
Speaker 1: So there's been a lot of investment in detection of

532
00:28:48,520 --> 00:28:51,400
Speaker 1: nuclear weapons activity, you mean, like here on Earth. Like

533
00:28:51,520 --> 00:28:54,480
Speaker 1: if you wanted to detect whether a nuclear bomb exploded

534
00:28:54,600 --> 00:28:57,040
Speaker 1: here on Earth, not in an alien planet, we have

535
00:28:57,200 --> 00:28:59,000
Speaker 1: techniques here on Earth to do that because I guess

536
00:28:59,080 --> 00:29:02,000
Speaker 1: if someone explodes a nuther bomb on the other side

537
00:29:02,000 --> 00:29:03,760
Speaker 1: of the world, in the middle of the ocean, you

538
00:29:03,800 --> 00:29:06,840
Speaker 1: may not necessarily know what happened, right, And if you're

539
00:29:07,440 --> 00:29:10,800
Speaker 1: a big country in a cold war or not, you

540
00:29:10,840 --> 00:29:13,560
Speaker 1: might want to know if your enemies are exploding bombs

541
00:29:13,680 --> 00:29:15,520
Speaker 1: or testing them, that's right, and you might not want

542
00:29:15,600 --> 00:29:17,560
Speaker 1: the other country to know that you're doing it. So,

543
00:29:17,640 --> 00:29:20,880
Speaker 1: like secret testing of nuclear weapons was a big industry

544
00:29:20,880 --> 00:29:23,240
Speaker 1: and a sort of an arms race of hiding nuclear

545
00:29:23,280 --> 00:29:27,080
Speaker 1: bomb detonations and nuclear weapons detections. I grew up in

546
00:29:27,120 --> 00:29:29,480
Speaker 1: Los Almos, which was certainly a nerve center for this

547
00:29:29,560 --> 00:29:32,400
Speaker 1: kind of stuff. My mom actually worked on a nuclear

548
00:29:32,480 --> 00:29:35,680
Speaker 1: non proliferation technology when she was at Los Almos, trying

549
00:29:35,680 --> 00:29:38,360
Speaker 1: to detect if people are blowing up nuclear bombs and

550
00:29:38,400 --> 00:29:40,080
Speaker 1: all this kind of stuff. So we have a lot

551
00:29:40,080 --> 00:29:42,080
Speaker 1: of ways to try to figure out if someone has

552
00:29:42,120 --> 00:29:44,480
Speaker 1: blown up a nuclear bomb here on Earth. Yeah, it

553
00:29:44,480 --> 00:29:46,760
Speaker 1: sounds like you would want to know. And it's kind

554
00:29:46,760 --> 00:29:49,840
Speaker 1: of interesting that we test nuclear bombs right Like, first

555
00:29:49,880 --> 00:29:51,400
Speaker 1: of all, I guess you have to test them right

556
00:29:51,400 --> 00:29:52,880
Speaker 1: now or the wise do not even know they work.

557
00:29:52,960 --> 00:29:55,440
Speaker 1: But it's amazing to me that we have tested nuclear

558
00:29:55,480 --> 00:29:57,640
Speaker 1: bombs here in the US, right in the desert back

559
00:29:57,640 --> 00:30:00,240
Speaker 1: in the fifties and sixties that there was all they did. Yeah,

560
00:30:00,280 --> 00:30:02,600
Speaker 1: they have done above ground tests here in the US.

561
00:30:02,720 --> 00:30:05,200
Speaker 1: You know, Alamagordo was the first site in New Mexico

562
00:30:05,320 --> 00:30:07,280
Speaker 1: and they tested them on a bunch of islands, which

563
00:30:07,320 --> 00:30:10,360
Speaker 1: was terrible and like totally obliterated them. And then there

564
00:30:10,400 --> 00:30:13,600
Speaker 1: was an atmosphereic test ban treaty, so you couldn't test

565
00:30:13,600 --> 00:30:16,640
Speaker 1: the nuclear weapons in the atmosphere anymore, which is good,

566
00:30:16,680 --> 00:30:19,560
Speaker 1: and they moved the testing underground. So in the United States,

567
00:30:19,560 --> 00:30:22,320
Speaker 1: for example, there's the Nevada underground test site where they

568
00:30:22,360 --> 00:30:24,680
Speaker 1: blow these weapons up underground. But there hasn't been any

569
00:30:24,760 --> 00:30:28,600
Speaker 1: recent testing. There's a Comprehensive Test Band treaty now and

570
00:30:28,680 --> 00:30:31,800
Speaker 1: so instead people now do simulations. They try to understand

571
00:30:32,200 --> 00:30:35,120
Speaker 1: what would happen in the event of a nuclear explosion,

572
00:30:35,320 --> 00:30:38,120
Speaker 1: or try to model what's happening to the nuclear weapons

573
00:30:38,200 --> 00:30:40,720
Speaker 1: we have now, are they going to survive? The whole

574
00:30:40,720 --> 00:30:43,960
Speaker 1: big industry called stockpile stewardship to try to make sure

575
00:30:43,960 --> 00:30:47,640
Speaker 1: that our nuclear weapons would still work if we fired them. Interesting,

576
00:30:47,680 --> 00:30:50,480
Speaker 1: So it's a treaty. So like with Russian other countries,

577
00:30:50,520 --> 00:30:53,520
Speaker 1: we have a handshake agreement that you can't test. Basically,

578
00:30:53,800 --> 00:30:56,720
Speaker 1: you can't test nuclear weapons anymore. Yeah, there's a Comprehensive

579
00:30:56,800 --> 00:31:00,280
Speaker 1: Nuclear Test Band Treaty signed in nineteen ninety six. And

580
00:31:00,320 --> 00:31:03,360
Speaker 1: you know, these treatings are always complicated because some nations

581
00:31:03,400 --> 00:31:05,960
Speaker 1: don't ratify them. They're signed by presidents and then their

582
00:31:06,320 --> 00:31:08,560
Speaker 1: local parliaments don't agree to them. But yeah, it's been

583
00:31:08,560 --> 00:31:10,800
Speaker 1: a long time since there was sort of a public

584
00:31:10,840 --> 00:31:13,720
Speaker 1: test of a nuclear weapon out in the open, all right.

585
00:31:13,720 --> 00:31:16,560
Speaker 1: So if someone did test the weapon or use one

586
00:31:16,640 --> 00:31:18,480
Speaker 1: here on earth, how can we detect them? So we

587
00:31:18,520 --> 00:31:20,680
Speaker 1: have a few ways to try to spot this. Number

588
00:31:20,680 --> 00:31:23,480
Speaker 1: one is seismic. If you do test underground, then it's

589
00:31:23,480 --> 00:31:26,200
Speaker 1: going to shake the earth and the earth will ring

590
00:31:26,320 --> 00:31:28,960
Speaker 1: like a bell. Shock waves will pass all the way

591
00:31:28,960 --> 00:31:31,080
Speaker 1: around the Earth, and you can detect them in other

592
00:31:31,120 --> 00:31:34,720
Speaker 1: places the same way we can put detectors in California

593
00:31:34,800 --> 00:31:37,600
Speaker 1: that can spot earthquakes in Japan or in other parts

594
00:31:37,640 --> 00:31:41,320
Speaker 1: of the world. You can detect large seismic events all

595
00:31:41,360 --> 00:31:43,920
Speaker 1: over the world. Right because I guess the shock waves

596
00:31:44,080 --> 00:31:46,800
Speaker 1: of these earthquakes or nuclear explosions, they kind of go

597
00:31:46,920 --> 00:31:49,080
Speaker 1: through the rock of the Earth, right, even though it's

598
00:31:49,120 --> 00:31:52,600
Speaker 1: like lava and molten it'll still kind of propagate sound

599
00:31:52,600 --> 00:31:56,240
Speaker 1: waves lava sound waves. Imagine the Earth is just like

600
00:31:56,240 --> 00:31:58,320
Speaker 1: a ball of metal and you ring it with a hammer,

601
00:31:58,360 --> 00:32:00,480
Speaker 1: then those sound chock waves are going to bounce all

602
00:32:00,480 --> 00:32:03,560
Speaker 1: around inside it. And this is actually really cool for

603
00:32:03,760 --> 00:32:07,200
Speaker 1: studying the interior of the Earth. You ring the earth

604
00:32:07,240 --> 00:32:09,520
Speaker 1: and how those shockwaves move through the earth tells you

605
00:32:09,560 --> 00:32:12,040
Speaker 1: about what's inside of it. And like the boundary layers,

606
00:32:12,160 --> 00:32:14,120
Speaker 1: that's actually given us a lot of clues about what's

607
00:32:14,160 --> 00:32:18,040
Speaker 1: inside the earth. Is watching the impact of earthquakes sending

608
00:32:18,080 --> 00:32:21,320
Speaker 1: shockwaves through the earth. It can be hard, however, to

609
00:32:21,320 --> 00:32:24,640
Speaker 1: tell the difference between an earthquake and a smaller nuclear

610
00:32:24,680 --> 00:32:27,200
Speaker 1: weapons explosion, and they try to do a lot these

611
00:32:27,240 --> 00:32:29,800
Speaker 1: days to hide the nuclear weapons explosions by having like

612
00:32:29,920 --> 00:32:33,040
Speaker 1: dampers materials which will absorb a lot of this energy

613
00:32:33,080 --> 00:32:35,520
Speaker 1: instead of properly getting it into the earth. And one

614
00:32:35,560 --> 00:32:38,320
Speaker 1: thing that they've done to try to distinguish between earthquakes

615
00:32:38,320 --> 00:32:41,640
Speaker 1: and nuclear bombs is to listen to it, to take

616
00:32:41,680 --> 00:32:44,520
Speaker 1: the data and translate it into an audio file. And

617
00:32:44,560 --> 00:32:47,440
Speaker 1: it turns out the human brains are pretty good at

618
00:32:47,480 --> 00:32:51,720
Speaker 1: distinguishing the sound of an earthquake versus the sound of

619
00:32:51,760 --> 00:32:55,840
Speaker 1: a nuclear bomb going off. Okay, so sound waves through

620
00:32:55,840 --> 00:32:57,720
Speaker 1: the earth is one way we can detect them here

621
00:32:57,720 --> 00:32:59,760
Speaker 1: on Earth. What are some of the other ways? Other

622
00:32:59,760 --> 00:33:02,680
Speaker 1: ways are through the air and through the water. So

623
00:33:02,880 --> 00:33:06,320
Speaker 1: if you, for example, blowing up underwater, then you create

624
00:33:06,520 --> 00:33:10,560
Speaker 1: hydroacoustic signals. It's just like shock waves through the earth,

625
00:33:10,600 --> 00:33:12,400
Speaker 1: but instead now you're make sways through the water, and

626
00:33:12,440 --> 00:33:15,560
Speaker 1: water is very good at transmitting sound. Right. The speed

627
00:33:15,600 --> 00:33:17,920
Speaker 1: of sound through water is faster than it is through air,

628
00:33:18,160 --> 00:33:20,880
Speaker 1: and so sound travels pretty far. All the way across

629
00:33:20,920 --> 00:33:23,120
Speaker 1: the globe, which is one reason why they think that

630
00:33:23,160 --> 00:33:25,920
Speaker 1: like whales can talk to each other from different parts

631
00:33:25,920 --> 00:33:28,520
Speaker 1: of the planet. You know, they think whales in Japan

632
00:33:28,680 --> 00:33:30,880
Speaker 1: might be able to hear the songs of whales off

633
00:33:30,920 --> 00:33:33,560
Speaker 1: of Alaska, this kind of stuff. And so in the

634
00:33:33,600 --> 00:33:35,680
Speaker 1: same way, if you blow up a nuclear bomb anywhere

635
00:33:35,680 --> 00:33:37,720
Speaker 1: neither its not even just in the water, then the

636
00:33:37,760 --> 00:33:40,120
Speaker 1: seismic waves will propagate through the ocean. And we have

637
00:33:40,120 --> 00:33:43,240
Speaker 1: a lot of listening stations underwater to try to listen

638
00:33:43,360 --> 00:33:47,200
Speaker 1: for all sorts of activity, but including nuclear explosions. Is

639
00:33:47,200 --> 00:33:49,840
Speaker 1: that allowed? Can you test nuclear weapons in the water?

640
00:33:50,160 --> 00:33:53,760
Speaker 1: Definitely not allowed, but has been done in the past, right,

641
00:33:54,040 --> 00:33:56,320
Speaker 1: all right, how else you can also look more directly

642
00:33:56,320 --> 00:33:58,960
Speaker 1: for the radioactivity, right if you do blow up a

643
00:33:59,040 --> 00:34:01,720
Speaker 1: nuclear bomb, and there's a lot of radiation emitted and

644
00:34:01,920 --> 00:34:04,400
Speaker 1: radioactive elements. So one thing we do is we try

645
00:34:04,440 --> 00:34:07,280
Speaker 1: to sample by airplane. You know, you have airplanes flying

646
00:34:07,280 --> 00:34:11,600
Speaker 1: all around the world, and they're sampling for unusual radioactive isotopes,

647
00:34:11,640 --> 00:34:15,000
Speaker 1: some of which are indicative of nuclear explosions. Even if

648
00:34:15,040 --> 00:34:17,719
Speaker 1: you like test it underground, a little bit of these

649
00:34:17,800 --> 00:34:21,319
Speaker 1: radioactive isotopes will eventually leak. It's not always easy to

650
00:34:21,320 --> 00:34:25,000
Speaker 1: tell where the nuclear bomb explosion happened using these techniques,

651
00:34:25,040 --> 00:34:27,720
Speaker 1: because it depends on how it's carried by the wind

652
00:34:27,840 --> 00:34:30,759
Speaker 1: and the weather and how recently it happened. But you

653
00:34:30,800 --> 00:34:33,160
Speaker 1: can sort of tell that one maybe did happen if

654
00:34:33,160 --> 00:34:35,880
Speaker 1: you pick up a signal of these particular fingerprints of

655
00:34:35,880 --> 00:34:39,760
Speaker 1: a nuclear bomb through their radioactive isotopes. So that's happening

656
00:34:39,880 --> 00:34:42,640
Speaker 1: right now. Like there are aeroplanes out there up there

657
00:34:43,480 --> 00:34:47,279
Speaker 1: basically sweeping the earth like a like a roombay. Exactly.

658
00:34:47,680 --> 00:34:49,720
Speaker 1: I don't know the details because they're not public because

659
00:34:49,760 --> 00:34:52,160
Speaker 1: like the US doesn't want Russia, for example, to know

660
00:34:52,280 --> 00:34:55,040
Speaker 1: exactly how it's monitoring it, because then Russia will know

661
00:34:55,320 --> 00:34:57,799
Speaker 1: how best to evade it. So it's a whole game

662
00:34:57,840 --> 00:35:01,000
Speaker 1: of secrecy. But absolutely I'm sure that the Russians and

663
00:35:01,040 --> 00:35:04,920
Speaker 1: the Americans are both monitoring the atmosphere in high altitude

664
00:35:04,920 --> 00:35:07,360
Speaker 1: planes to try to detect whether the other side is

665
00:35:07,400 --> 00:35:10,200
Speaker 1: cheating on the Test band treaty. We're also basically looking

666
00:35:10,200 --> 00:35:12,640
Speaker 1: for these explosions, right like if you can have satellites

667
00:35:12,680 --> 00:35:15,560
Speaker 1: maybe with camera strain at the Earth looking waiting for

668
00:35:15,600 --> 00:35:17,880
Speaker 1: these flashes of light, absolutely, and that's one of the

669
00:35:17,880 --> 00:35:20,200
Speaker 1: most powerful ways we can see these and one of

670
00:35:20,200 --> 00:35:23,040
Speaker 1: the ways that might apply to alien detonations, which is

671
00:35:23,440 --> 00:35:26,360
Speaker 1: just look with satellites, right, we have pictures basically the

672
00:35:26,480 --> 00:35:28,600
Speaker 1: entire surface of the Earth, and we can look for

673
00:35:28,840 --> 00:35:31,719
Speaker 1: high energy sources of gamma rays and X rays, which

674
00:35:31,719 --> 00:35:34,640
Speaker 1: are unusual and you don't expect to produce these things

675
00:35:34,680 --> 00:35:36,680
Speaker 1: in lots of different ways. And so if you see

676
00:35:36,760 --> 00:35:39,759
Speaker 1: one of these signals, flashes of gamma rays, especially the

677
00:35:39,800 --> 00:35:42,520
Speaker 1: double peak signature, then you have a very strong smoking

678
00:35:42,560 --> 00:35:45,120
Speaker 1: gun signature of a nuclear detonation. But what if you

679
00:35:45,280 --> 00:35:48,239
Speaker 1: detonated underground, like deep underground would be with the X

680
00:35:48,360 --> 00:35:50,719
Speaker 1: rays and gamma rays still make it through all those

681
00:35:50,800 --> 00:35:53,520
Speaker 1: layers of rock. It depends a lot on the shielding, right,

682
00:35:53,560 --> 00:35:55,800
Speaker 1: and sometimes they try to shield it with heavier metals

683
00:35:55,880 --> 00:35:58,840
Speaker 1: or they go deep deep underground. X rays can penetrate

684
00:35:58,880 --> 00:36:01,600
Speaker 1: a lot of material. Rays tend to be more ionizing,

685
00:36:01,680 --> 00:36:04,040
Speaker 1: so they do end up getting absorbed, but it depends

686
00:36:04,080 --> 00:36:06,160
Speaker 1: a lot on the depth. All right, Well, that's how

687
00:36:06,239 --> 00:36:09,000
Speaker 1: you can tell if someone exploded something here on Earth.

688
00:36:09,320 --> 00:36:12,680
Speaker 1: But what about the question of aliens exploding things in

689
00:36:12,719 --> 00:36:17,200
Speaker 1: their planets? Could we detect alien explosions or an alien

690
00:36:17,239 --> 00:36:20,040
Speaker 1: nuclear war. So if aliens have the same kind of

691
00:36:20,040 --> 00:36:23,240
Speaker 1: technology that we have, meaning they're blowing up bombs similar

692
00:36:23,239 --> 00:36:24,840
Speaker 1: to the ones we have, then we can look for

693
00:36:24,840 --> 00:36:27,520
Speaker 1: the same signatures from their planets that we would look

694
00:36:27,560 --> 00:36:31,520
Speaker 1: for on Earth. Obviously, we can't look for seismic activity

695
00:36:31,680 --> 00:36:35,920
Speaker 1: or hydroacoustic activity, and we can't sample their atmosphere directly.

696
00:36:36,160 --> 00:36:37,799
Speaker 1: The best way to do it would be to look

697
00:36:37,840 --> 00:36:41,160
Speaker 1: for these gamma ray flashes. And of course we already

698
00:36:41,280 --> 00:36:44,600
Speaker 1: have telescopes that are scanning the sky looking for gamma

699
00:36:44,680 --> 00:36:48,239
Speaker 1: rays because lots of non alien sources of gamma rays

700
00:36:48,320 --> 00:36:51,360
Speaker 1: are very interesting to us, and there's even a huge

701
00:36:51,480 --> 00:36:55,040
Speaker 1: fun physics mystery about gamma ray flashes. These things are

702
00:36:55,040 --> 00:36:58,800
Speaker 1: called gamma ray bursts that come from all over the sky.

703
00:36:59,120 --> 00:37:01,800
Speaker 1: We don't really understand them. They last for like sometimes

704
00:37:01,800 --> 00:37:05,080
Speaker 1: a few seconds, sometimes like thirty seconds. We think they

705
00:37:05,200 --> 00:37:08,960
Speaker 1: might be due to the collapse of supermassive stars, but

706
00:37:09,000 --> 00:37:12,560
Speaker 1: they generate very bright flashes of gamma rays that are

707
00:37:12,600 --> 00:37:15,520
Speaker 1: sort of similar to what you might expect from a

708
00:37:15,640 --> 00:37:19,200
Speaker 1: nuclear detonation. M I think you're sort of painting the

709
00:37:19,320 --> 00:37:23,359
Speaker 1: scenario where We're basically looking at the sky right with

710
00:37:23,520 --> 00:37:26,920
Speaker 1: giant antennas that can detect gamma rays. And if we

711
00:37:27,040 --> 00:37:29,600
Speaker 1: somehow are pointing to a particular planet or star and

712
00:37:29,640 --> 00:37:32,120
Speaker 1: we see a big flash or a signal, then that

713
00:37:32,160 --> 00:37:34,480
Speaker 1: could be the sign that the amiens blew themselves up.

714
00:37:34,560 --> 00:37:36,400
Speaker 1: It could be the sign. As one of the members

715
00:37:36,400 --> 00:37:40,040
Speaker 1: of Listener Panel pointed out, it might be hard to distinguish. Right.

716
00:37:40,360 --> 00:37:43,719
Speaker 1: On one hand, it's cool that supermassive stars collapse and

717
00:37:43,760 --> 00:37:46,120
Speaker 1: give off gamma ray bursts. On the other hand, it's

718
00:37:46,160 --> 00:37:48,480
Speaker 1: a bit of a bomber because it makes it harder

719
00:37:48,480 --> 00:37:52,279
Speaker 1: to distinguish between alien nuclear bomb gamma ray bursts and

720
00:37:52,440 --> 00:37:55,760
Speaker 1: just natural sources of gamma ray bursts. But I guess

721
00:37:55,760 --> 00:37:59,080
Speaker 1: if it was a super massive star collapsing, wouldn't we

722
00:37:59,160 --> 00:38:01,600
Speaker 1: also see other signs that go along with it that

723
00:38:01,680 --> 00:38:04,799
Speaker 1: wouldn't go along with a nuclear explosion. It could be,

724
00:38:05,000 --> 00:38:07,400
Speaker 1: And one thing we're doing is to try to study

725
00:38:07,480 --> 00:38:10,040
Speaker 1: these gamma ray bursts in more detail and see whether

726
00:38:10,080 --> 00:38:13,279
Speaker 1: they come along with other signs like flashes of neutrinos

727
00:38:13,400 --> 00:38:16,279
Speaker 1: or other things we can see in the optical To

728
00:38:16,320 --> 00:38:18,520
Speaker 1: try to figure these things out. We don't always have

729
00:38:18,560 --> 00:38:20,080
Speaker 1: a lot of warning, right, We don't know when it's

730
00:38:20,120 --> 00:38:21,719
Speaker 1: going to happen. We just see like, oh wow, that

731
00:38:21,840 --> 00:38:24,120
Speaker 1: was a big flash of gamma rays from this spot

732
00:38:24,200 --> 00:38:26,640
Speaker 1: in the sky. You don't always have time to train

733
00:38:26,800 --> 00:38:29,680
Speaker 1: other telescopes on that spot to get sort of multi

734
00:38:29,880 --> 00:38:32,840
Speaker 1: channel data, and they do look kind of similar. In fact,

735
00:38:33,080 --> 00:38:36,799
Speaker 1: when we first discovered gamma ray bursts, scientists thought that

736
00:38:36,880 --> 00:38:40,839
Speaker 1: what they were seeing were gamma rays from earthbound detonations

737
00:38:40,840 --> 00:38:43,640
Speaker 1: of nuclear weapons. They thought they had just picked up

738
00:38:43,840 --> 00:38:48,480
Speaker 1: the Russian explosions because I would explain the signal too, Yeah,

739
00:38:48,600 --> 00:38:51,239
Speaker 1: because that would have explained the signal. Now, gamma ray

740
00:38:51,280 --> 00:38:55,520
Speaker 1: bursts come from really really incredibly powerful events. These things

741
00:38:55,520 --> 00:38:58,480
Speaker 1: release enormous amounts of energy, so we can see gamma

742
00:38:58,520 --> 00:39:01,560
Speaker 1: ray bursts from all across the universe. We've seen them

743
00:39:01,600 --> 00:39:04,600
Speaker 1: from really really far away, like millions and millions, almost

744
00:39:04,600 --> 00:39:08,120
Speaker 1: a billion light years away, because they are so powerful.

745
00:39:08,280 --> 00:39:11,120
Speaker 1: Some of these things released like ten to the forty

746
00:39:11,200 --> 00:39:15,799
Speaker 1: four jewels of energy just in the gamma rays, and

747
00:39:15,880 --> 00:39:18,399
Speaker 1: so they're very bright, very powerful. We can see these

748
00:39:18,440 --> 00:39:21,600
Speaker 1: things from very very far away. Our nuclear bombs are

749
00:39:21,640 --> 00:39:24,759
Speaker 1: not nearly as powerful as these other natural sources of

750
00:39:24,880 --> 00:39:28,200
Speaker 1: gamma rays, so they would be relatively dim in comparison.

751
00:39:28,360 --> 00:39:30,239
Speaker 1: You mean if there was an alien looking at us

752
00:39:30,280 --> 00:39:33,279
Speaker 1: for these gamma ray bursts, Yeah, exactly. If aliens were

753
00:39:33,280 --> 00:39:37,280
Speaker 1: watching our nuclear explosions and they had technology similar to hours,

754
00:39:37,680 --> 00:39:40,399
Speaker 1: they would not be able to see our explosions from

755
00:39:40,480 --> 00:39:43,160
Speaker 1: very very far away because our explosions are not that

756
00:39:43,280 --> 00:39:46,960
Speaker 1: bright compared to gamma ray bursts. Well, sort of depends

757
00:39:46,960 --> 00:39:49,759
Speaker 1: on how many nukes we detonate at the same time.

758
00:39:49,960 --> 00:39:52,360
Speaker 1: It does. But if you imagine, like a doomsday scenario,

759
00:39:52,400 --> 00:39:54,520
Speaker 1: you take all of our nuclear weapons, you set them

760
00:39:54,560 --> 00:39:57,400
Speaker 1: all off at the same time, you can calculate, like

761
00:39:57,440 --> 00:40:00,600
Speaker 1: how much energy in gamma ray bursts would be emitted.

762
00:40:00,840 --> 00:40:05,320
Speaker 1: It's only like ten to the nineteen jewels, Like obviously cataclysmic,

763
00:40:05,560 --> 00:40:09,480
Speaker 1: terrible scenario, enough energy to devastate civilization on Earth. But

764
00:40:09,560 --> 00:40:11,719
Speaker 1: compared to gamma ray bursts, which are ten to the

765
00:40:11,880 --> 00:40:14,800
Speaker 1: forty four jewels, we're talking about ten to the twenty

766
00:40:14,800 --> 00:40:18,480
Speaker 1: five times less powerful than a gamma ray burst, So

767
00:40:18,520 --> 00:40:22,600
Speaker 1: they're relatively dim compared to these other astrophysical sources. It's

768
00:40:22,680 --> 00:40:27,000
Speaker 1: twenty five orders of magnitude weaker, but I guess you're saying, like,

769
00:40:27,080 --> 00:40:30,440
Speaker 1: if we do see a gamma ray burst and we're

770
00:40:30,520 --> 00:40:33,000
Speaker 1: not sure if it's an alien or a star collapsing,

771
00:40:33,280 --> 00:40:36,120
Speaker 1: I mean that would mean that this alien civilization blew

772
00:40:36,200 --> 00:40:40,399
Speaker 1: up twenty five orders of magnude, many more bombs than

773
00:40:40,400 --> 00:40:42,919
Speaker 1: we did. We're a bomb that was twenty five orders

774
00:40:43,000 --> 00:40:45,399
Speaker 1: of magnitude bigger than ours. Yeah, it depends on how

775
00:40:45,440 --> 00:40:47,640
Speaker 1: far away they are. If they are as far away

776
00:40:47,640 --> 00:40:50,399
Speaker 1: as some of these really distant gamma ray bursts, then

777
00:40:50,440 --> 00:40:53,400
Speaker 1: you're right, they would have like much much bigger nuclear

778
00:40:53,520 --> 00:40:56,759
Speaker 1: arsenals than we have, like ten to twenty five times

779
00:40:56,800 --> 00:41:01,960
Speaker 1: as powerful, or they had or they exactly exactly kind

780
00:41:02,000 --> 00:41:04,879
Speaker 1: of tense. But if you're imagining an alien civilization with

781
00:41:04,920 --> 00:41:07,440
Speaker 1: the power of our nuclear weapons and they had some

782
00:41:07,480 --> 00:41:09,960
Speaker 1: sort of cataclysmic event where they blew them all up

783
00:41:10,000 --> 00:41:12,479
Speaker 1: at once, then you can ask how far away would

784
00:41:12,480 --> 00:41:14,839
Speaker 1: they be for us to detect it. Our gamma ray

785
00:41:14,880 --> 00:41:18,080
Speaker 1: sensors are pretty sensitive, but remember that things get much

786
00:41:18,200 --> 00:41:20,920
Speaker 1: dimmer as you get further away, so the sources have

787
00:41:21,000 --> 00:41:24,040
Speaker 1: to be very bright to be visible. For an alien

788
00:41:24,120 --> 00:41:27,640
Speaker 1: nuclear war at human levels to look about as bright

789
00:41:27,680 --> 00:41:30,600
Speaker 1: as a typical gamma ray burst, that we see it

790
00:41:30,640 --> 00:41:34,480
Speaker 1: could only be around eight to ten astronomical units away

791
00:41:35,040 --> 00:41:38,120
Speaker 1: because it wouldn't be nearly as bright as its source

792
00:41:38,520 --> 00:41:41,359
Speaker 1: as gamma ray bursts that are typically much further. So

793
00:41:41,480 --> 00:41:44,280
Speaker 1: eight to ten AU that's like the distance to Pluto.

794
00:41:44,480 --> 00:41:47,040
Speaker 1: Beyond that, we might still be able to pick it up,

795
00:41:47,040 --> 00:41:50,080
Speaker 1: but it would start getting dimmer very fast because remember

796
00:41:50,360 --> 00:41:53,760
Speaker 1: the next star over is much further away than Pluto.

797
00:41:53,960 --> 00:41:56,720
Speaker 1: So it's possible to see it in another star system,

798
00:41:57,000 --> 00:42:00,680
Speaker 1: but not a guarantee, and our abilities fade very quickly

799
00:42:00,920 --> 00:42:04,680
Speaker 1: as you consider even further star systems. So if like

800
00:42:04,760 --> 00:42:07,080
Speaker 1: there are aliens in Pluto and they had a nuclear

801
00:42:07,120 --> 00:42:09,799
Speaker 1: war and they detonated all their nuclear weapons, then we

802
00:42:09,800 --> 00:42:13,160
Speaker 1: would see it through the gamma ray radiation. But if

803
00:42:13,200 --> 00:42:15,719
Speaker 1: it happened like and in another source system, it'd be

804
00:42:15,800 --> 00:42:18,440
Speaker 1: way too dim, or would it, or maybe maybe just

805
00:42:18,520 --> 00:42:21,480
Speaker 1: need better instruments. I mean, you're not saying it's impossible,

806
00:42:21,600 --> 00:42:23,560
Speaker 1: or you're saying it's impossible, or that it's really hard.

807
00:42:23,680 --> 00:42:25,520
Speaker 1: I'm not saying it's impossible. I'm saying it's at the

808
00:42:25,680 --> 00:42:28,959
Speaker 1: edge of our ability currently, like we can barely pick

809
00:42:29,080 --> 00:42:33,480
Speaker 1: up super bright, very distant gamma ray bursts, or we

810
00:42:33,520 --> 00:42:37,759
Speaker 1: could pick up less bright closer gamma ray bursts. Right,

811
00:42:37,920 --> 00:42:40,560
Speaker 1: there's sort of a line there between distance and brightness.

812
00:42:40,640 --> 00:42:42,719
Speaker 1: But we could also improve our technology and make our

813
00:42:42,719 --> 00:42:46,000
Speaker 1: gamma ray detectors more sensitive. Then we could see dimmer

814
00:42:46,040 --> 00:42:48,719
Speaker 1: things that were further away, including gamma ray bursts or

815
00:42:48,800 --> 00:42:52,040
Speaker 1: alien technology. Is definitely not impossible. But I think you

816
00:42:52,200 --> 00:42:54,680
Speaker 1: said that gamma ray are only one of the things

817
00:42:54,719 --> 00:42:56,759
Speaker 1: that come out of a nuclear explosion. There's also like

818
00:42:56,800 --> 00:42:59,919
Speaker 1: the actual visible light flash tour, and that's like many

819
00:43:00,080 --> 00:43:02,560
Speaker 1: times bigger than the gamma ray burst. Do we see

820
00:43:02,680 --> 00:43:06,400
Speaker 1: a star war happening just on the visible spectrum? We

821
00:43:06,480 --> 00:43:08,520
Speaker 1: might be able to, but the universe is a little

822
00:43:08,520 --> 00:43:11,839
Speaker 1: bit less transparent to that kind of light. Gamma rays

823
00:43:11,920 --> 00:43:15,160
Speaker 1: are awesome because most of the universe is transparent to them,

824
00:43:15,239 --> 00:43:17,439
Speaker 1: but visible life, for example, is more likely to get

825
00:43:17,440 --> 00:43:20,400
Speaker 1: blocked by gas or dust or these kinds of things.

826
00:43:20,640 --> 00:43:25,279
Speaker 1: But it is possible, and we should look for multiple signatures. Right,

827
00:43:25,320 --> 00:43:27,200
Speaker 1: So we can look at the gamma rays, we can

828
00:43:27,239 --> 00:43:29,520
Speaker 1: look in the visible light. We certainly should keep an

829
00:43:29,520 --> 00:43:32,520
Speaker 1: eye on that. There are also other more subtle ways

830
00:43:32,560 --> 00:43:36,319
Speaker 1: that we might be able to detect nuclear weapons explosions

831
00:43:36,440 --> 00:43:40,160
Speaker 1: on other planets and to distinguish them from gamma ray bursts.

832
00:43:40,200 --> 00:43:43,240
Speaker 1: The point you were making earlier about telling the difference

833
00:43:43,239 --> 00:43:46,239
Speaker 1: between nuclear weapons and gamma rays. All right, let's get

834
00:43:46,280 --> 00:43:49,280
Speaker 1: into those other ways we could detect an alien nuclear

835
00:43:49,280 --> 00:43:52,440
Speaker 1: war and whether or not it might ever happen. But

836
00:43:52,560 --> 00:44:08,680
Speaker 1: first let's take another quick break. All right, So what

837
00:44:08,719 --> 00:44:10,719
Speaker 1: do you think is the scenaro here where aliens have

838
00:44:10,760 --> 00:44:14,360
Speaker 1: a nuclear war? Do you think they just disagree about something?

839
00:44:15,080 --> 00:44:18,280
Speaker 1: Do you think it's inevitable for all civilizations to eventually

840
00:44:18,320 --> 00:44:21,440
Speaker 1: snuff themselves out? I don't know. I've heard this theory,

841
00:44:21,480 --> 00:44:24,600
Speaker 1: you know, the great filter that the reason we haven't

842
00:44:24,680 --> 00:44:28,160
Speaker 1: seen aliens or been visited by their probes is that

843
00:44:28,320 --> 00:44:31,839
Speaker 1: technological civilizations don't tend to last very long because they

844
00:44:31,880 --> 00:44:35,480
Speaker 1: tend to destroy themselves through climate change or annihilation or

845
00:44:35,560 --> 00:44:38,719
Speaker 1: war or whatever. And that's possible, I suppose, but it

846
00:44:38,760 --> 00:44:41,600
Speaker 1: seems to me like a huge amount of projection. It's

847
00:44:41,640 --> 00:44:44,439
Speaker 1: imagining that aliens are a lot like humans, and their

848
00:44:44,480 --> 00:44:47,879
Speaker 1: psychology and their struggles and their sociology is a lot

849
00:44:47,920 --> 00:44:50,480
Speaker 1: like ours. And that's possible, But it also seems to

850
00:44:50,520 --> 00:44:52,680
Speaker 1: me to be possible for it to be completely different,

851
00:44:52,719 --> 00:44:54,520
Speaker 1: for their politics to be totally different, and they never

852
00:44:54,560 --> 00:44:58,200
Speaker 1: even invent nuclear weapons. So I think it's too big

853
00:44:58,200 --> 00:45:01,839
Speaker 1: a question without really data to speculate on. Yeah, it's

854
00:45:01,840 --> 00:45:03,759
Speaker 1: a big unknown, but I think it has maybe kind

855
00:45:03,760 --> 00:45:05,840
Speaker 1: of the basis and the idea that, you know, anything

856
00:45:05,880 --> 00:45:10,640
Speaker 1: that evolves evolution works by competition, right, and so basically

857
00:45:10,680 --> 00:45:14,560
Speaker 1: any intelligent society will most likely it kind of come

858
00:45:14,600 --> 00:45:17,520
Speaker 1: up like we did, being having this kind of balanced,

859
00:45:17,600 --> 00:45:21,280
Speaker 1: this idea of competition and killing each other but also

860
00:45:21,520 --> 00:45:24,279
Speaker 1: being nice to each other. Yeah. We had an astrozoologist

861
00:45:24,360 --> 00:45:26,879
Speaker 1: on the podcast recently who made that point. He said,

862
00:45:26,880 --> 00:45:30,200
Speaker 1: predation is inevitable in evolution. You will eventually have one

863
00:45:30,239 --> 00:45:33,200
Speaker 1: guy that wants to eat the neighboring guy. And that's

864
00:45:33,280 --> 00:45:36,319
Speaker 1: probably true, but it doesn't mean that it doesn't mean

865
00:45:36,360 --> 00:45:39,759
Speaker 1: you can't like progress past your evolutionary impulses. Right. Our

866
00:45:39,760 --> 00:45:42,759
Speaker 1: behavior now is quite different from the behavior in which

867
00:45:42,800 --> 00:45:46,399
Speaker 1: we evolve, much more complex cooperative society. So I don't

868
00:45:46,400 --> 00:45:50,320
Speaker 1: know that it's inevitable that you're dominated by that competitive nature,

869
00:45:50,400 --> 00:45:53,399
Speaker 1: but hey, let's find out hopefully, listen, let's not find

870
00:45:53,400 --> 00:45:57,200
Speaker 1: out the negative outcome the hard way. So you're saying

871
00:45:57,239 --> 00:46:00,799
Speaker 1: before that for us to see alien nuclear explosions in

872
00:46:00,880 --> 00:46:04,040
Speaker 1: other planets, I mean they would have to basically detonate

873
00:46:04,200 --> 00:46:07,319
Speaker 1: twenty five orders of Maude, many more bombs that all

874
00:46:07,320 --> 00:46:10,160
Speaker 1: of humanity has for us to even have a chance

875
00:46:10,200 --> 00:46:12,360
Speaker 1: to see it. Yes, for us to detect these bright flashes,

876
00:46:12,680 --> 00:46:15,280
Speaker 1: they would have to have a much more substantial arsenal

877
00:46:15,360 --> 00:46:18,000
Speaker 1: than we have twenty five orders of magnitude more right,

878
00:46:18,360 --> 00:46:22,040
Speaker 1: like bombs that could destroy you. I don't even know

879
00:46:22,120 --> 00:46:24,920
Speaker 1: the number for that, but twenty five orders of magnitude

880
00:46:24,920 --> 00:46:27,239
Speaker 1: many more planets. Yeah, sorry, I don't know if I

881
00:46:27,280 --> 00:46:29,560
Speaker 1: said twenty five times right, it's ten to the twenty

882
00:46:29,560 --> 00:46:32,240
Speaker 1: five times, So it's one with a lot of zeros

883
00:46:32,320 --> 00:46:34,840
Speaker 1: in front of it. Absolutely, But if they do have

884
00:46:34,920 --> 00:46:38,440
Speaker 1: a canterclismic nuclear war, there will also be other impacts

885
00:46:38,640 --> 00:46:41,280
Speaker 1: on their planet that we might be able to detect

886
00:46:41,320 --> 00:46:43,759
Speaker 1: even if we don't spot the gamma ray burst. And

887
00:46:43,800 --> 00:46:45,759
Speaker 1: these are the kind of things we might be able

888
00:46:45,760 --> 00:46:48,920
Speaker 1: to spot from planets in other solar systems. And number

889
00:46:48,920 --> 00:46:53,000
Speaker 1: one on that list is changes in their atmosphere. You mean,

890
00:46:53,040 --> 00:46:56,400
Speaker 1: like maybe we don't detect the explosion itself, that of

891
00:46:56,480 --> 00:47:00,480
Speaker 1: the nuclear war. But we can detect their nuclear winter exactly,

892
00:47:00,760 --> 00:47:03,640
Speaker 1: their nuclear winter. If you do have this kind of

893
00:47:03,680 --> 00:47:05,800
Speaker 1: event where you blow up a lot of nuclear bombs

894
00:47:05,800 --> 00:47:09,319
Speaker 1: in your atmosphere, it would really change your atmosphere. Number One,

895
00:47:09,360 --> 00:47:13,080
Speaker 1: it would very briefly make your atmosphere glow. Right, you're

896
00:47:13,160 --> 00:47:16,000
Speaker 1: dumping a huge amount of energy into your atmosphere. It

897
00:47:16,040 --> 00:47:19,240
Speaker 1: would ionize a bunch of the gases from the radiation

898
00:47:19,400 --> 00:47:22,480
Speaker 1: produced by a lot of the byproducts, and so the

899
00:47:22,520 --> 00:47:25,640
Speaker 1: atmosphere itself would glow sort of like the Northern lights.

900
00:47:25,840 --> 00:47:28,520
Speaker 1: Ionized air tends to emit this kind of glow. We've

901
00:47:28,520 --> 00:47:30,279
Speaker 1: seen it on Earth, we've seen it on Venus, we've

902
00:47:30,280 --> 00:47:32,759
Speaker 1: seen it on Mars. And so if you have a

903
00:47:32,760 --> 00:47:35,839
Speaker 1: lot of nuclear bombs, then their atmosphere would have this

904
00:47:36,000 --> 00:47:38,040
Speaker 1: air glow and we might be able to spot that.

905
00:47:38,200 --> 00:47:40,920
Speaker 1: Wait wait, wait, we could see their atmosphere glow like

906
00:47:41,000 --> 00:47:44,640
Speaker 1: how like with telescopes. Yeah, telescopes pointed at these planets

907
00:47:44,920 --> 00:47:47,680
Speaker 1: might be able to gather some information about the light

908
00:47:47,719 --> 00:47:50,360
Speaker 1: that's coming directly from the planet. Right, we now have

909
00:47:50,600 --> 00:47:54,720
Speaker 1: direct imaging of exoplanets. And if you see, for example,

910
00:47:55,000 --> 00:47:58,839
Speaker 1: a spike in the oxygen line, that increases the oxygen

911
00:47:59,000 --> 00:48:02,480
Speaker 1: rapidly by a factor of ten than our telescopes could

912
00:48:02,480 --> 00:48:05,280
Speaker 1: spot that. But wait, if we can see their amosphere glow,

913
00:48:05,400 --> 00:48:09,840
Speaker 1: surely we would see their explosions themselves, right, Like explosions

914
00:48:09,840 --> 00:48:12,400
Speaker 1: would be pretty flashy, right, he said, forty percent of

915
00:48:12,400 --> 00:48:16,040
Speaker 1: a nuclear explosions energy goes into visible light. I mean,

916
00:48:16,040 --> 00:48:18,399
Speaker 1: if we can see their atmospherre glow, surely we would

917
00:48:18,400 --> 00:48:21,360
Speaker 1: see their like a big flash before the explosion or

918
00:48:21,880 --> 00:48:24,839
Speaker 1: during the explosion. The explosion itself might not be bright

919
00:48:24,960 --> 00:48:27,480
Speaker 1: enough for us to see. It'll also be really short lived.

920
00:48:27,680 --> 00:48:29,920
Speaker 1: What we're talking about here is seeing a change in

921
00:48:29,960 --> 00:48:33,200
Speaker 1: the atmosphere chemistry, which we usually detect from how the

922
00:48:33,320 --> 00:48:37,000
Speaker 1: light from the planet's star passes through its atmosphere or

923
00:48:37,080 --> 00:48:39,759
Speaker 1: reflex off its atmosphere. So the light we get from

924
00:48:39,800 --> 00:48:42,560
Speaker 1: these planets is not from any source on the planet itself,

925
00:48:42,680 --> 00:48:45,600
Speaker 1: but from the star, which is why it's visible at all.

926
00:48:45,719 --> 00:48:48,719
Speaker 1: The air glow might last longer than the flash, and

927
00:48:48,760 --> 00:48:50,920
Speaker 1: so it might be easier to spot. But what we're

928
00:48:50,920 --> 00:48:53,759
Speaker 1: doing is thinking about, like what are the multiple signatures,

929
00:48:54,400 --> 00:48:56,359
Speaker 1: Because in the end, the story is going to be

930
00:48:56,480 --> 00:48:59,959
Speaker 1: that you probably can't conclude that you've seen an alien

931
00:49:00,040 --> 00:49:02,680
Speaker 1: an explosion based on only one of these signatures, because

932
00:49:02,680 --> 00:49:05,000
Speaker 1: there are other ways to mimic any one of them.

933
00:49:05,440 --> 00:49:08,040
Speaker 1: So to conclude you've seen alien signatures, what you're going

934
00:49:08,080 --> 00:49:12,440
Speaker 1: to want is multiple pieces of evidence. I see, like

935
00:49:12,480 --> 00:49:15,400
Speaker 1: the afterglow will last longer, so there's more likelihood that

936
00:49:15,440 --> 00:49:17,160
Speaker 1: will see it. But also it's sort of like more

937
00:49:17,200 --> 00:49:21,080
Speaker 1: of a telltale sign. If planet is glowing more than

938
00:49:21,120 --> 00:49:23,520
Speaker 1: it should, then you can maybe infer that there was

939
00:49:23,520 --> 00:49:25,880
Speaker 1: an explosion there exactly, like maybe you see a gamma

940
00:49:25,920 --> 00:49:27,879
Speaker 1: ray burst and you see a bright flash of light

941
00:49:28,000 --> 00:49:30,200
Speaker 1: from the visible light emission and you're wondering, like, well,

942
00:49:30,400 --> 00:49:33,320
Speaker 1: was that some sort of star collapsing or was it

943
00:49:33,400 --> 00:49:35,400
Speaker 1: an alien nuclear bomb? Then you can look for the

944
00:49:35,440 --> 00:49:38,040
Speaker 1: air glow. There are other effects in the atmosphere as well,

945
00:49:38,440 --> 00:49:41,040
Speaker 1: like these blasts tend to produce a lot of nitrogen

946
00:49:41,080 --> 00:49:45,080
Speaker 1: oxides which react with and deplete ozone, And so if

947
00:49:45,080 --> 00:49:48,120
Speaker 1: you're watching the atmosphere of this planet, then you're looking

948
00:49:48,120 --> 00:49:50,799
Speaker 1: in the UV light, you can detect changes in the

949
00:49:50,840 --> 00:49:53,920
Speaker 1: ozone layer. So a lot of these other signals require

950
00:49:53,920 --> 00:49:56,600
Speaker 1: you to be looking at one of these planets already

951
00:49:56,640 --> 00:50:01,239
Speaker 1: in studying its atmosphere and seeing change in its atmosphere,

952
00:50:01,280 --> 00:50:03,920
Speaker 1: so it increases an ionization of the gases that lead

953
00:50:03,960 --> 00:50:07,520
Speaker 1: to air glow or decrease in the ozone layer by

954
00:50:07,560 --> 00:50:10,560
Speaker 1: interaction from some of the byproducts of the blast. Or

955
00:50:10,600 --> 00:50:14,040
Speaker 1: if you just like see the atmosphere become opaque, Right,

956
00:50:14,080 --> 00:50:15,920
Speaker 1: you have a bunch of nuclear bombs go off, it's

957
00:50:15,960 --> 00:50:18,040
Speaker 1: going to throw up a huge amount of either vapor

958
00:50:18,480 --> 00:50:21,759
Speaker 1: or dust or something to make the atmosphere more opaque,

959
00:50:22,040 --> 00:50:24,600
Speaker 1: and that could last for years. Right, We're talking about

960
00:50:24,600 --> 00:50:27,360
Speaker 1: a nuclear winter. And so if you see an atmosphere

961
00:50:27,400 --> 00:50:30,479
Speaker 1: becomes suddenly more opaque than it was before, that tells

962
00:50:30,480 --> 00:50:34,720
Speaker 1: you something big happened in that atmosphere, Like if there's

963
00:50:34,800 --> 00:50:36,680
Speaker 1: more dust in the atmosphere, Although that could also be

964
00:50:36,719 --> 00:50:40,440
Speaker 1: an asteroid, right, Like if an asteroid hits planet, it

965
00:50:40,480 --> 00:50:43,480
Speaker 1: would also cause a big flash of light and also

966
00:50:43,520 --> 00:50:45,560
Speaker 1: a lot put a lot of stuff in the atmosphere, right,

967
00:50:46,040 --> 00:50:48,759
Speaker 1: Or would it look differently? Is it's not radioactive? Yeah,

968
00:50:48,800 --> 00:50:51,960
Speaker 1: an asteroid wouldn't look exactly the same as a nuclear

969
00:50:52,000 --> 00:50:54,480
Speaker 1: bomb because it wouldn't deplete the ozone in the same way.

970
00:50:54,520 --> 00:50:56,400
Speaker 1: It might not cause the same amount of air glow

971
00:50:56,719 --> 00:50:59,359
Speaker 1: because it wouldn't have the same sort of radioactive byproducts,

972
00:50:59,520 --> 00:51:01,560
Speaker 1: but a lot of the signatures would be the same.

973
00:51:01,800 --> 00:51:03,640
Speaker 1: It would throw up a lot of dust in the atmosphere,

974
00:51:03,680 --> 00:51:06,880
Speaker 1: probably make the atmosphere opaque for years as well, but

975
00:51:06,880 --> 00:51:09,160
Speaker 1: you probably wouldn't also get the gamma ray burst. So

976
00:51:09,200 --> 00:51:11,719
Speaker 1: there's lots of things out there in the universe that

977
00:51:11,800 --> 00:51:16,400
Speaker 1: could make signatures similar to alien nuclear total annihilation, global

978
00:51:16,400 --> 00:51:19,440
Speaker 1: thermonuclear war, but not all of them. So if you

979
00:51:19,560 --> 00:51:22,680
Speaker 1: happen to see like several of these signatures all together

980
00:51:23,200 --> 00:51:26,319
Speaker 1: from an exoplanet, then you could probably conclude that there

981
00:51:26,360 --> 00:51:28,560
Speaker 1: were aliens and they had just had a very very

982
00:51:28,640 --> 00:51:32,600
Speaker 1: bad day. Or maybe they were celebrating something, you know,

983
00:51:33,280 --> 00:51:35,800
Speaker 1: it's just how they do fireworks in that ailing culture.

984
00:51:36,120 --> 00:51:39,960
Speaker 1: Maybe they detected us and they were celebrating because they

985
00:51:39,960 --> 00:51:41,759
Speaker 1: were going to get to eat a good mule latter.

986
00:51:42,080 --> 00:51:44,120
Speaker 1: Or maybe they try to have some fireworks and they

987
00:51:44,160 --> 00:51:47,560
Speaker 1: accidentally shot the fireworks right at their nuclear arsenal and

988
00:51:47,640 --> 00:51:50,600
Speaker 1: set it off. I think I've seen that on TikTok.

989
00:51:50,880 --> 00:51:52,560
Speaker 1: All right, well, I kind of feel like we have

990
00:51:52,600 --> 00:51:55,640
Speaker 1: to be looking for these things though, right, like gamma rays,

991
00:51:55,680 --> 00:51:57,840
Speaker 1: it's not like we have a camera looking out the

992
00:51:57,880 --> 00:52:01,200
Speaker 1: whole universe looking for gamma ray. Gamma detectors here on

993
00:52:01,239 --> 00:52:03,440
Speaker 1: Earth are very specific. Likely we have to point them

994
00:52:03,480 --> 00:52:06,680
Speaker 1: at specific stars and stuff, right, So it seems kind

995
00:52:06,680 --> 00:52:10,360
Speaker 1: of unlikely that will just happen to catch another civilization

996
00:52:10,840 --> 00:52:14,160
Speaker 1: having their nuclear war just as we're pointing our telescope

997
00:52:14,160 --> 00:52:16,319
Speaker 1: at them. I yeah, exactly. I think some people were

998
00:52:16,360 --> 00:52:18,680
Speaker 1: hoping that this would be a very easy way, a

999
00:52:18,760 --> 00:52:23,279
Speaker 1: very obvious way to identify alien civilizations. But unfortunately they're

1000
00:52:23,280 --> 00:52:25,920
Speaker 1: not as bright as you might imagine, and the universe

1001
00:52:26,040 --> 00:52:28,000
Speaker 1: is very very large, and there are other ways to

1002
00:52:28,040 --> 00:52:30,080
Speaker 1: create a lot of these signals, and so you have

1003
00:52:30,160 --> 00:52:31,960
Speaker 1: to be very lucky. You'd have to be looking at

1004
00:52:31,960 --> 00:52:35,120
Speaker 1: a planet basically when this happens, and have been looking

1005
00:52:35,160 --> 00:52:38,160
Speaker 1: at it beforehand so you could see the changes. And

1006
00:52:38,239 --> 00:52:40,560
Speaker 1: this is one of the big problems in detecting alien

1007
00:52:40,560 --> 00:52:44,680
Speaker 1: civilizations is just the deep length of time. Right, Maybe

1008
00:52:44,719 --> 00:52:47,640
Speaker 1: alien civilizations have existed and they've all killed each other

1009
00:52:47,719 --> 00:52:49,839
Speaker 1: and those signals came to Earth, but like a few

1010
00:52:49,960 --> 00:52:53,120
Speaker 1: hundred years ago and we missed it, right. Jill Tarter

1011
00:52:53,239 --> 00:52:56,040
Speaker 1: is famous for saying that we've been watching for aliens

1012
00:52:56,040 --> 00:53:00,520
Speaker 1: for a cosmically insignificant amount of time, and adding looking

1013
00:53:00,520 --> 00:53:03,719
Speaker 1: for nuclear explosions is a good way to increase our

1014
00:53:03,760 --> 00:53:07,800
Speaker 1: ability to see them, But it doesn't change this problem

1015
00:53:07,840 --> 00:53:10,600
Speaker 1: that we've only been looking very very briefly, and aliens

1016
00:53:10,640 --> 00:53:13,359
Speaker 1: could have existed and lived for millions of years and

1017
00:53:13,440 --> 00:53:16,040
Speaker 1: died off recently and we still wouldn't have seen it. Yeah,

1018
00:53:16,040 --> 00:53:17,600
Speaker 1: I see what you're saying. You're saying like, maybe these

1019
00:53:17,640 --> 00:53:20,759
Speaker 1: star wars happened a long long time ago and the

1020
00:53:20,840 --> 00:53:23,480
Speaker 1: galaxy far far away. Is that kind of what the

1021
00:53:23,600 --> 00:53:28,839
Speaker 1: conclusion of scientists is, Yes, exactly, that's entirely possible. Which

1022
00:53:28,880 --> 00:53:31,080
Speaker 1: I feel like I've seen that in a movie already.

1023
00:53:31,280 --> 00:53:33,920
Speaker 1: Did somebody have that idea already? Dang it, man, every

1024
00:53:33,920 --> 00:53:36,040
Speaker 1: time I have a good idea, it's still your Nobel

1025
00:53:36,120 --> 00:53:41,240
Speaker 1: Prize again and my ten billion dollars in box office receipts.

1026
00:53:41,360 --> 00:53:43,200
Speaker 1: All right, Well, I think it's still kind of interesting

1027
00:53:43,239 --> 00:53:45,840
Speaker 1: to think about, right, It's still worth thinking about because

1028
00:53:46,000 --> 00:53:49,480
Speaker 1: we do happen to see the city signals, right then

1029
00:53:49,600 --> 00:53:52,240
Speaker 1: we would know a lot about not only the idea

1030
00:53:52,280 --> 00:53:54,920
Speaker 1: that we're out there alone or not, but also like

1031
00:53:55,719 --> 00:53:58,759
Speaker 1: what these other aliens are capable of. Yeah, and these

1032
00:53:58,800 --> 00:54:01,800
Speaker 1: aliens could have court developed technologies that are far beyond

1033
00:54:01,880 --> 00:54:04,560
Speaker 1: what we have and create flashes of light much much

1034
00:54:04,600 --> 00:54:07,640
Speaker 1: brighter than the kinds of things we're imagining, and we

1035
00:54:07,640 --> 00:54:09,560
Speaker 1: should keep our eyes open for that. I think the

1036
00:54:09,600 --> 00:54:11,840
Speaker 1: spirit of this is just to try to be inclusive

1037
00:54:11,880 --> 00:54:13,760
Speaker 1: about the kind of things we're looking for, to increase

1038
00:54:13,800 --> 00:54:17,359
Speaker 1: our chances of seeing anything at all. Yeah, or I think,

1039
00:54:17,400 --> 00:54:19,560
Speaker 1: as we talked about in other episodes, like you might

1040
00:54:19,600 --> 00:54:22,160
Speaker 1: be limited in your imagination, right, Like maybe if you

1041
00:54:22,160 --> 00:54:26,800
Speaker 1: imagine giant space civilizations and have bombs that are twenty

1042
00:54:26,800 --> 00:54:30,240
Speaker 1: five orders of mine need to bigger than our bombs,

1043
00:54:30,400 --> 00:54:33,319
Speaker 1: then we would be able to see that kind of spectacle. Yeah,

1044
00:54:33,360 --> 00:54:36,680
Speaker 1: we talked about the Kardaship scale of civilizations. Some aliens

1045
00:54:36,760 --> 00:54:39,359
Speaker 1: might have tapped into all of the energy output of

1046
00:54:39,400 --> 00:54:43,920
Speaker 1: their sun and built a huge laser capable of vaporizing planets.

1047
00:54:44,280 --> 00:54:45,960
Speaker 1: You know, I think I've seen that in the movie also,

1048
00:54:46,239 --> 00:54:48,719
Speaker 1: but it could be real, and if they shoot that

1049
00:54:48,800 --> 00:54:50,920
Speaker 1: laser in our direction, we might be able to see it.

1050
00:54:51,040 --> 00:54:54,280
Speaker 1: That is exactly the plot of these Star Wars trilogies.

1051
00:54:55,280 --> 00:54:58,239
Speaker 1: They literally suck a son into their gun and then

1052
00:54:58,280 --> 00:55:01,120
Speaker 1: shoot it at other planets. Not something we're recommending, but

1053
00:55:01,160 --> 00:55:03,479
Speaker 1: if it happens, we might be able to see it. Yeah,

1054
00:55:03,520 --> 00:55:06,480
Speaker 1: and you'll be there with your popcorn, gleefully looking at

1055
00:55:06,520 --> 00:55:10,839
Speaker 1: the extinction of thousands or billions of alien lives as

1056
00:55:10,880 --> 00:55:13,440
Speaker 1: they melt my eyeballs. All right, well, we hope they

1057
00:55:13,680 --> 00:55:16,399
Speaker 1: give you something to think about, and maybe think about

1058
00:55:16,440 --> 00:55:20,080
Speaker 1: the trajectory of our own civilization, Like do we want

1059
00:55:20,120 --> 00:55:23,640
Speaker 1: to be known to other alien species by our last moments?

1060
00:55:24,440 --> 00:55:27,440
Speaker 1: Or should we be working harder to work things out

1061
00:55:27,520 --> 00:55:30,000
Speaker 1: between us so that they see us for other reasons.

1062
00:55:30,200 --> 00:55:32,240
Speaker 1: Or maybe we should take all of our nuclear bombs

1063
00:55:32,239 --> 00:55:34,160
Speaker 1: and launch them into space and blow them up out

1064
00:55:34,200 --> 00:55:36,920
Speaker 1: there so aliens know we're here. You mean, like a

1065
00:55:36,960 --> 00:55:41,080
Speaker 1: dinner bell, Like ring a different dinner bell. No, like

1066
00:55:41,120 --> 00:55:45,680
Speaker 1: an invitation to a party, right, a dinner party? Sounds

1067
00:55:45,680 --> 00:55:47,560
Speaker 1: like maybe we should put that up for a vote

1068
00:55:47,760 --> 00:55:50,279
Speaker 1: before we do that. All right, Well, we hope you

1069
00:55:50,360 --> 00:55:52,920
Speaker 1: enjoyed that. Thanks for joining us, See you next time.

1070
00:56:00,880 --> 00:56:03,680
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain

1071
00:56:03,760 --> 00:56:07,680
Speaker 1: the Universe is a production of iHeartRadio. For more podcasts

1072
00:56:07,800 --> 00:56:12,360
Speaker 1: from iHeartRadio, visit the iHeartRadio, app, Apple podcasts, or wherever

1073
00:56:12,480 --> 00:56:14,160
Speaker 1: you listen to your favorite shows.