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Speaker 1: Hey, Daniel, do you remember the first time you saw

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Speaker 1: an X ray of yourself? I do. Actually, I once

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Speaker 1: broke a tiny little bone in my wrist the first

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Speaker 1: time I went snowboarding. And were you amazed to get

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Speaker 1: to see the inside of your body? I was really

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Speaker 1: excited about it, but then I was kind of underwhelmed.

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Speaker 1: It was sort of like a big whitewash. It was

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Speaker 1: hard to actually understand like what was going on inside there,

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Speaker 1: but the doctor could read it right. Oh. Yeah. To

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Speaker 1: him it was like crystal clear. He was like, oh,

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Speaker 1: this bone, that bone, the other bone. He knew exactly

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Speaker 1: what was happening. He spotted this tiny little break. And

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Speaker 1: that's pretty amazing, isn't it? How you know the knowledge

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Speaker 1: of an experience? I how they can pull out data

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Speaker 1: that other people can't see. Yeah, exactly. It makes me

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Speaker 1: wonder how X ray astronomers see the universe. Yeah, as

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Speaker 1: long as they don't go snowboarding, they're probably safe. I

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Speaker 1: hope the universe doesn't break its wrist. I am or

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Speaker 1: handmade cartoonists and the creator of PhD comics. I'm Daniel.

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Speaker 1: I'm a particle physicist, but I'm no longer a snowboarder.

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Speaker 1: Where you ever, Daniel, It doesn't sound like it went well.

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Speaker 1: I was a snowboarder for about five minutes and then

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Speaker 1: I retired. But no, it didn't go well. You achieve

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Speaker 1: what you wanted to achieve in that area of activity

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Speaker 1: and then decided to focus on physics. Yeah, exactly, I

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Speaker 1: crossed it off the list. Well. Welcome to our podcast,

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Speaker 1: Daniel and Jorge Explain the Universe, a production of I

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Speaker 1: Heart Radio in which we don't talk about snowboarding and skiing,

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Speaker 1: but instead we focus our energy on trying to understand

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Speaker 1: the universe, the vast reaches of space, the crazy explosions

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Speaker 1: going on inside stars, the weird things planets are doing

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Speaker 1: whizzing around stars in our galaxy and other galaxies and

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Speaker 1: in far reaches of the universe, and we try to

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Speaker 1: explain all of it to you without making too many

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Speaker 1: banana jokes. Although there is no out there in space, right,

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Speaker 1: there is galactic snow. Technically there's a lot of ice. Yeah,

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Speaker 1: we have ice giants in our Solar System. There's a

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Speaker 1: huge amount of frozen water all over the Solar System

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Speaker 1: and all over the universe. Water turns out, is not

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Speaker 1: actually that rare. It's only rare to be liquid on

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Speaker 1: the surface of a body like it is here on Earth.

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Speaker 1: Who do you think will be the first person to

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Speaker 1: snowboard on Neptune? Probably an astronomer, definitely not me. Hopefully

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Speaker 1: where where a risk guard? That would be my advice,

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Speaker 1: because there are some crazy mountains out there and some

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Speaker 1: crazy different kinds of snow, Like I wonder if methane

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Speaker 1: snow is good for snowboarding on or not. Do you

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Speaker 1: think aliens have a lot of different words for snow

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Speaker 1: and like we do here on Earth. I don't know.

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Speaker 1: Maybe if aliens have a lot of wrists, then they

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Speaker 1: don't go snowboarding because you know, it's too easy to

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Speaker 1: break one. They're an increased risk. They have like eight risks,

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Speaker 1: increased risk risk. Well, there are a lot of interesting

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Speaker 1: planets and asteroids and comments out there in the universe,

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Speaker 1: and we've talked about a lot of the ones that

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Speaker 1: we can find here in our Solar System on our podcast,

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Speaker 1: and also we talked about finding planets in our galaxy.

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Speaker 1: But it's a big universe and who knows what's out

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Speaker 1: there beyond our galaxy? And a deep question we're always

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Speaker 1: asking about the universe. Is how unusual is our neighborhood?

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Speaker 1: You know, we spent most of the time on this

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Speaker 1: planet just looking in our immediate neighborhood, understanding our planet,

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Speaker 1: our solar system, and then wondering, is this weird or

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Speaker 1: is this typical? Are other stars out there? Do they

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Speaker 1: also have planets like ours? Or are we the only

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Speaker 1: solar system out there with multiple planets? Or maybe other

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Speaker 1: solar systems have like dozens of planets. And so in

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Speaker 1: the beginning, we usually just wonder and we speculate, And

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Speaker 1: now we're in an era where we can actually start looking. Yeah,

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Speaker 1: because we have spotted planets in other solar systems within

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Speaker 1: our galaxy. I think you know, right now we not

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Speaker 1: only know that there are thousands and thousands of them

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Speaker 1: out there, but we've also started being able to actually

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Speaker 1: see them and even like check the weather on them. Yeah,

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Speaker 1: it's really pretty amazing. We are living in an extraordinary

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Speaker 1: era because for thousands of years people have wondered about

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Speaker 1: that question, are their planets around other stars? And now

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Speaker 1: just in the last twenty five years, we know for

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Speaker 1: a fact the answer to that question, and the answers

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Speaker 1: are kind of exciting. Ryany tells us that there are

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Speaker 1: a lot of planets out there, and there are a

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Speaker 1: lot of them that are probably like Earth, and so

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Speaker 1: that's exciting to actually like know for a fact the

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Speaker 1: answer to questions people have been wondering about for thousands

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Speaker 1: of years. Yeah, but most of the ones we've seen,

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Speaker 1: or at least have detected so far, we've seen by

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Speaker 1: looking out into the stars at night, and most of

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Speaker 1: them are in our galaxy. Right, It's pretty much all

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Speaker 1: of those thousands of exo planets that we found are

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Speaker 1: in the Milky Way. Yeah, that's right, because the Milky

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Speaker 1: Way is sort of our galactic neighborhood. It's about a

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Speaker 1: hundred thousand light years across, and so it's the best

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Speaker 1: place to look at other stars because they're the ones

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Speaker 1: that are nearby. But then, of course our imagination reaches

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Speaker 1: further and wonders like, well, maybe the Milky Way is unusual,

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Speaker 1: Maybe the Milky Way is weird, or maybe it's typical,

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Speaker 1: and it makes us wonder what is it like to

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Speaker 1: be a planet around a star in a far away galaxy? Yeah,

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Speaker 1: because the Milky Way is not the only galaxy, right,

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Speaker 1: There are hundreds of billions of galaxies that we can

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Speaker 1: see or know about. There might be maybe an infinite

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Speaker 1: number of them. Yeah, I think the last count is

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Speaker 1: in the observable universe. There are more than two trillion

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Speaker 1: galaxies right, each with hundreds of billions of stars. And

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Speaker 1: as you say, that's just the observable universe, we have

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Speaker 1: no idea what fraction of the actual universe that is.

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Speaker 1: It could be literally zero volume fraction, because the universe

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Speaker 1: could be infinite. Yeah, and it is sort of possible

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Speaker 1: now that you mentioned it is it would be weird.

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Speaker 1: But it is maybe possible that maybe the Milky Way

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Speaker 1: is it is strange, right, Like, maybe our galaxy is

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Speaker 1: the only one that is stable enough or calm enough

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Speaker 1: or something enough for it to have stars with planets

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Speaker 1: with life and them. Yeah. Absolutely, And it's one of

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Speaker 1: my favorite kinds of questions because any answer to this

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Speaker 1: question is mind boggling. Either the Milky Way is weird

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Speaker 1: and it's the only one that has the conditions to

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Speaker 1: make these kind of planets. WHOA, that would be weird, right,

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Speaker 1: or it's not. And then all those other galaxies are

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Speaker 1: also teeming with planets, which makes the number of earthlike

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Speaker 1: planets in our universe a huge number. That's hard to

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Speaker 1: hold in your head, and it makes you really suspect

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Speaker 1: that the odds of life are high. Yeah, but I

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Speaker 1: guess the question is can we confirm news? Do we

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Speaker 1: know for sure there are other planets in other galaxies

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Speaker 1: besides the Milky Way? And so to be on the program,

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Speaker 1: we'll be asking the question can we find planets in

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Speaker 1: other galaxies far far away a long time ago? And Daniel,

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Speaker 1: that's literally true. Every galaxy we look at is far

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Speaker 1: far away and the light is coming to us from

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Speaker 1: a long time ago. So they're basically all the setting

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Speaker 1: for Star Wars. Yeah, you know, that actually did blow

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Speaker 1: my mind recently. I was watching the Star Wars movie

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Speaker 1: and you know when those words come out at the beginning,

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Speaker 1: a long long time ago in a galaxy far far away,

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Speaker 1: and it did sort of made me think about some

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Speaker 1: of our conversations where it's like, oh, that means, you know,

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Speaker 1: it's sort of happening in real time. It's just that

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Speaker 1: the light is just getting to us now. Yeah, well

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Speaker 1: it could have happened a long time ago and the

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Speaker 1: light could still be arriving, So you can imagine that

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Speaker 1: instead of watching it on your TV screen you're just

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Speaker 1: looking through a telescope watching these battles play out in

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Speaker 1: a far away galaxy. Of course, you know the events

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Speaker 1: have already occurred and you're just watching them. But that's

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Speaker 1: sort of just like watching a movie, right, and the

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Speaker 1: movie is totally filmed before you watch it. It's not

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Speaker 1: like they're acting it live or anything. But it's fun

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Speaker 1: to imagine. Yeah, but even a movie like Star Wars,

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Speaker 1: if you think about it, they only hang out in

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Speaker 1: one galaxy. You know, it's the Galactic Empire, the only

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Speaker 1: goal around the galaxy. They never go to different galaxies. Yeah,

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Speaker 1: that's right, And I think they use that sort of

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Speaker 1: as a mechanism to suggest this is impossibly distant. This

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Speaker 1: is some where we could never go. This is a

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Speaker 1: different part of the universe. Because galaxies are crazy far apart.

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Speaker 1: They're not just really bit right there, like fifty or

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Speaker 1: hundred thousand or two hundred thousand light years across. The

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Speaker 1: space between them is much much bigger than the size

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Speaker 1: of the galaxies, right. Galaxies tend to be millions of

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Speaker 1: light years apart. So it's like, you know, if your

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Speaker 1: house was out in the deep woods and the next

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Speaker 1: house wasn't for miles and miles away. Yeah, yeah, I

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Speaker 1: think galaxies are like hundreds of thousands of light years wide,

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Speaker 1: but there are millions of light years apart. Yeah, they're

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Speaker 1: like little islands. Yeah, they're like little islands. Yeah, there's

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Speaker 1: a lot of variation in the size of galaxies, but

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Speaker 1: roughly that's correct. They're like basically ten times further apart

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Speaker 1: than they are wide. All right, Well, then the question

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Speaker 1: is are their plan in those other galaxies, and if

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Speaker 1: there are, how could we ever find them or maybe

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Speaker 1: even see them. That's right, because we want to move

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Speaker 1: beyond just speculation. We don't want to just wonder if

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Speaker 1: they're there. We want actual facts, We want data, we

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Speaker 1: want observations, We want to know because science is not

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Speaker 1: just about guessing and speculating. It's about asking nature questions

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Speaker 1: and hearing the answers. And the best moments are when

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Speaker 1: those answers are a surprise. Yeah. So, as usual, we

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Speaker 1: were wondering how many people out there in the public

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Speaker 1: and in our audience know if we can find planets

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Speaker 1: in other galaxy. It seems to impossible. I'm gonna put

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Speaker 1: my money on impossible, but we'll see. So Daniel went

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Speaker 1: out there and solicited answers from people on the internet,

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Speaker 1: and so thank you everybody who participated as usual, And

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Speaker 1: if you would like to give a shot to answering

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Speaker 1: tough physics questions without any preparation, without any googling, without

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Speaker 1: any background knowledge, please write to us two questions at

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Speaker 1: Daniel and Jorge dot com. We would love to put

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Speaker 1: your baseless speculation on the podcast. So think about it

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Speaker 1: for a second. If someone as you, if you thought

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Speaker 1: you could find planets in other galaxies, and what would

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Speaker 1: you say. Here's what people had to say. I was

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Speaker 1: under the impression we had already found planets in other galaxies,

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Speaker 1: but maybe not. That does seem very far away now

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Speaker 1: that I think about it and say it out loud.

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Speaker 1: That really depends on the times, because someday we totally

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Speaker 1: could find those planets. For example, if we launch robotic probes,

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Speaker 1: maybe with self replicating capabilities, they could go on and

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Speaker 1: on for billion years and catalog everything they come across.

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Speaker 1: But since the universe is expanding, I don't think we

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Speaker 1: will ever be able to reach the other galaxies. Yes

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Speaker 1: we can. My guess is that we probably don't yet

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Speaker 1: have any method to tech exoplanets and other galaxies directly.

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Speaker 1: I would imagine that the only way to detect them

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Speaker 1: would be indirectly, possibly from gravitational effects on that stars. Sure,

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Speaker 1: eventually we can, but I don't think we can now.

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Speaker 1: The distances are just too far for us to see

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Speaker 1: the wobble of the star with the planet orbiting around it. Well,

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Speaker 1: I can't think of a way then with the current

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Speaker 1: techlorldsy we could do that, all right, A lot of

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Speaker 1: optimism here. Somebody just said, yes, we can see sip

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Speaker 1: with it was that Obama didn't sound like him? Yeah, exactly.

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Speaker 1: I think there's a lot of good optimism here, and

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Speaker 1: also some great ideas, I like, you know, launching robotic

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Speaker 1: probes to other galaxies, though that would take a long

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Speaker 1: long time for them to get there and then report back,

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Speaker 1: so graduate students don't propose that for your PhD. Yeah.

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Speaker 1: And also it seems like somebody here thought that we

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Speaker 1: had already found planets in other galaxies. I guess, um, Yeah,

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Speaker 1: it's sort of hard to remember that distinction between stars

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Speaker 1: in our galley sea and stars in other galaxies. And

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Speaker 1: remember that when you look out in the night sky

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Speaker 1: and you see stars, all of those stars are stars

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Speaker 1: in our galaxy to the naked eye, a distant galaxy

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Speaker 1: is too faint for you to make out the galaxy

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Speaker 1: by itself. It takes like a telescope or a good

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Speaker 1: camera and you have to like build up that light

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Speaker 1: over several hours or days in order to see those

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Speaker 1: galaxies because they are so far away. Yeah, and if

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Speaker 1: you do see a galaxy on a telescope or on

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Speaker 1: a photo, it really just looks like a little smudge

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Speaker 1: from Earth. Unless you have like an amazing super telescope,

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Speaker 1: it's really almost impossible to make out the individual stars

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Speaker 1: in them. For most galaxies, that's true because they're really distant.

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Speaker 1: For the closest galaxies, they are actually quite large in

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Speaker 1: the night sky, like Andromeda. If you could see it

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Speaker 1: it was bright enough for you to see, it would

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Speaker 1: be larger in the sky than the full moon. Oh really, wow,

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Speaker 1: I didn't know that. Yeah, it's pretty incredible. So if

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Speaker 1: you look at a picture of Andrameda, it's taken over

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Speaker 1: many many hours or sometimes many nights just to build

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Speaker 1: up enough photons for you to see it. It's just

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Speaker 1: so far away. It's not very bright, but it's huge,

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Speaker 1: and so it takes up a big fraction of our sky. Wow,

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Speaker 1: it's pretty cool. All right. Well, let's get into this

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Speaker 1: topic then of how we would find planets in those

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Speaker 1: other galaxies. And I guess we should start by maybe

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Speaker 1: recapping how we know about planets in this galaxy. How

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Speaker 1: can we possibly know there are planets around us? Yeah,

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Speaker 1: it's pretty cool, and these are techniques that were developed

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Speaker 1: again just in the last couple of decades. You know,

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Speaker 1: for a long time people have wondered about this, But

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Speaker 1: planets around other stars are hard to see because those

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Speaker 1: stars are pretty far away. We're talking about light years

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Speaker 1: and light years away, and then the planets are really

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Speaker 1: close to their star in comparison to the distance from

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Speaker 1: here to there. I've heard you say before, and I

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Speaker 1: like this analogy that it's sort of like looking for

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Speaker 1: a tennis ball around a street light on the other

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Speaker 1: side of the country. It's very difficult to see a

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Speaker 1: very small thing next to a very bright thing. Yeah,

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Speaker 1: because suns are pretty bright, and planets don't. They don't glow.

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Speaker 1: Did you reflect light? That's right, they just reflect light,

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Speaker 1: and so it's very very difficult to see them directly.

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Speaker 1: So people came up with a few really clever techniques

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Speaker 1: to try to deduce the presence of planets, and these

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Speaker 1: days we actually have a few that are pretty successful. Historically, though,

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Speaker 1: the first one that really worked is something called the

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Speaker 1: wobble method, and this is based on the idea that

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Speaker 1: the planet doesn't just orbit the star. The planet in

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Speaker 1: the star sort of orbit each other because while the

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Speaker 1: planet is moving around the gravity of the star, the

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Speaker 1: planet is also a big massive object and it tugs

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Speaker 1: on the star. So the planet in the star together

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Speaker 1: actually orbit the center of mass of those two objects.

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Speaker 1: What this means is that if a star has a

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Speaker 1: planet around it, it wobbles a little bit, It moves

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Speaker 1: a little bit, sort of like shakes in the sky.

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Speaker 1: It's not stationary relative to us, and this is something

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Speaker 1: we can see, So we can see the gravitational effect

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Speaker 1: of a planet on its star by watching it wiggle. Yeah,

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Speaker 1: it's pretty amazing. We tend to think of our Sun,

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Speaker 1: for example, as being stationary and all the planets are

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Speaker 1: going around it. But the Sun is actually kind of

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Speaker 1: wiggling and getting pulled this way and that way by Jupiter,

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Speaker 1: by Us, a little bit, by Mars. It's not like

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Speaker 1: fixing space. Yeah, it's mostly by Jupiter though, and you

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Speaker 1: know this is not a huge effect. It's a subtle

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Speaker 1: effect because the star is usually most of the mass

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Speaker 1: of everything in the Solar system, Like in our Solar system,

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Speaker 1: the Sun is of the mass of the Solar System

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Speaker 1: and Jupiter is about of the rest of it. So

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Speaker 1: if you're looking at our Solar system from really really

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Speaker 1: far away, you could probably detect the effect of Jupiter

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Speaker 1: as a little wiggle on the location of the Sun.

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Speaker 1: But it wouldn't be a huge effect. It's not like

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Speaker 1: the Sun is moving around Jupiter the same way Jupiter

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Speaker 1: is moving around the Sun. It's a much smaller effect

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Speaker 1: because the Sun has so much more mass. Yeah, okay,

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Speaker 1: so you can look at a star and if you

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Speaker 1: see a wiggle, you know that it has a planet

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Speaker 1: around it, But that doesn't tell you much about the

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Speaker 1: planet itself, right, So there are other ways to tell that. Yeah,

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Speaker 1: you can basically just tell the mass of the planet

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Speaker 1: by the amount of the wiggle. And you can't see

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Speaker 1: the wiggle sort of side a side, right, we don't

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Speaker 1: have enough angular resolution and like see stars moving at

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Speaker 1: that resolution. But what you can do is see the

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Speaker 1: wiggle sort of back and forth. Is the star moves

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Speaker 1: away from us and then comes closer. It changes the

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Speaker 1: frequency of the light that the star is sending us

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Speaker 1: is a little bit of a Doppler shift. So that's

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Speaker 1: how we see it actually wiggling. You see a wiggle

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Speaker 1: in the color, like the star looks a little blue,

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Speaker 1: a little red, a little blue, and a little it

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Speaker 1: and if it looks regular enough, you think, hey, there's

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Speaker 1: a planet there. Yeah, and that can tell you the

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Speaker 1: mass of the planet, because you have to know how

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Speaker 1: heavy the planet is to pull on the star at

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Speaker 1: that amount, And they'll tell you a little bit about

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Speaker 1: sort of the rotation of that planet around the star,

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Speaker 1: or at least the star's rotation around the center of mass,

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Speaker 1: because that affects like how long it takes to go

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Speaker 1: back and then forth. But it doesn't tell us something

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Speaker 1: really key, which is how big is the planet. And

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Speaker 1: we're interested in knowing like are these planets really hot

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Speaker 1: and dense? Are they big fluffy blobs? You know, we're

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Speaker 1: interested in like planets that might have life on them.

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Speaker 1: So this method can't tell you the radius of the planets.

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Speaker 1: You don't really know what's going on with the planet.

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Speaker 1: But yeah, there are other methods yeah, it just gives

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Speaker 1: you a wobbly estimate. Yeah, exactly. All right, well, let's

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Speaker 1: get into some of the other ways. We know that

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Speaker 1: there are planets in other stars in our galaxy and beyond.

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Speaker 1: But first let's take a quick break. All right, we're

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Speaker 1: talking about finding planets in other galaxies. We know there

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Speaker 1: are planets here under our feet and in our Solar system,

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Speaker 1: and we've seen thousands of planets in our galaxy, in

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Speaker 1: other stars in our galaxy. But the question is are

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Speaker 1: there planets in other galaxies? Have we seen them? Can

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Speaker 1: we see them? Is that impossible? What can we know

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Speaker 1: about them? Nothing is impossible. What we think is impossible

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Speaker 1: in a hundred years will be like an undergraduate research project.

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Speaker 1: You know. That's what I love about the progress of science.

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Speaker 1: Only the impossible is impossible. Yeah, what's impossible today is boring.

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Speaker 1: Next week it's an iPhone app and there exactly. Yeah.

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Speaker 1: And so we're talking about ways to learn more about

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Speaker 1: these planets around stars in our galaxy. Yes, and and

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Speaker 1: they all sort of involved looking at the star that

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Speaker 1: the planet revolves around. Right, that's mostly the the idea,

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Speaker 1: because you know, the star is so brad it's really

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Speaker 1: hard to see the actual planet, Yeah, exactly. So mostly

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Speaker 1: we're looking at the effect on the star of the planet,

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Speaker 1: and so one effect is that it shakes the star.

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Speaker 1: The other is that we can actually have a little

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Speaker 1: bit of an eclipse, like if it's lined up perfectly

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Speaker 1: so that sometimes the planet passes between us and this

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Speaker 1: other star, and that just you know, has to be

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Speaker 1: by chance that the plane of that solar system is

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Speaker 1: aligned to the planet passes between us and the other star.

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Speaker 1: It will block some of the light of that star,

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Speaker 1: and not completely, of course, because the planet is typically

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Speaker 1: much much smaller than the star, but it will pass

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Speaker 1: in front of it, and you will see a dip

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Speaker 1: in the amount of light you're getting from the star.

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Speaker 1: And you can see this regularly. Can go dip and

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Speaker 1: then back up, and dip and then back up, and

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Speaker 1: so that's a really good sign that there's something, some

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Speaker 1: sort of dark mass orbiting that star. Right. It's kind

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Speaker 1: of like when you're watching a movie and someone stands

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Speaker 1: up in front of you, you know, they temporarily kind

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Speaker 1: of block the light from the screen. That's kind of

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Speaker 1: how it is. Right, It's like a big source of

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Speaker 1: light and something moves in front of it you the

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Speaker 1: overall light from that will sort of go down, and

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Speaker 1: if they did that, you know, every two minutes or so,

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Speaker 1: you would get pretty annoyed. But that's the scenario here,

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Speaker 1: is that we see this regularly. So this is a

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Speaker 1: really awesome method, not just because it's harder to fake

380
00:19:36,880 --> 00:19:39,240
Speaker 1: because you're seeing this thing like happen all the time

381
00:19:39,280 --> 00:19:41,440
Speaker 1: you see regularly if you watch the star long enough,

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00:19:41,720 --> 00:19:45,239
Speaker 1: but also because you can tell the size of the planet. Right,

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Speaker 1: The bigger the planet, the more light it blocks. The

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Speaker 1: smaller the planet, the less light it blocks. So you

385
00:19:50,160 --> 00:19:53,760
Speaker 1: can measure the radius of the planet, which is super

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00:19:53,840 --> 00:19:56,040
Speaker 1: duper cool because if you know the mass of the

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Speaker 1: planet and it's radius, you can tell it's density and

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00:19:59,240 --> 00:20:01,360
Speaker 1: that gives you a lot of clues about like what

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00:20:01,480 --> 00:20:04,159
Speaker 1: it's made out of. Is it mostly rock? Is it iron?

390
00:20:04,480 --> 00:20:06,879
Speaker 1: Is it just a big loose ball of ice? Is

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00:20:06,880 --> 00:20:09,320
Speaker 1: it just a fluffy collection of gas? Like that tells

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00:20:09,400 --> 00:20:12,359
Speaker 1: us so much more about what the planet is, all right,

393
00:20:12,400 --> 00:20:14,880
Speaker 1: So that's another way to tell if a star has

394
00:20:14,880 --> 00:20:17,359
Speaker 1: planets around it, But that also has some negatives, right,

395
00:20:17,400 --> 00:20:20,040
Speaker 1: Like you can only see the planet if it happens

396
00:20:20,040 --> 00:20:22,159
Speaker 1: to go in front of you between you and the

397
00:20:22,200 --> 00:20:25,800
Speaker 1: sun and the star, and um, there are other things

398
00:20:25,800 --> 00:20:28,400
Speaker 1: that could maybe causing this, right, yeah, exactly, other things

399
00:20:28,440 --> 00:20:30,159
Speaker 1: could be passing in front of it. Doesn't have to

400
00:20:30,160 --> 00:20:32,560
Speaker 1: be a planet, it could be some other weird kind

401
00:20:32,560 --> 00:20:35,359
Speaker 1: of star, you know, like a brown dwarf for you know,

402
00:20:35,480 --> 00:20:37,560
Speaker 1: some sort of neutron star or something. So you don't

403
00:20:37,600 --> 00:20:40,280
Speaker 1: necessarily know, but you can get a lot of information

404
00:20:40,320 --> 00:20:42,040
Speaker 1: about the composition of it, so you can rule a

405
00:20:42,080 --> 00:20:44,000
Speaker 1: lot of that kind of stuff out. And this is

406
00:20:44,040 --> 00:20:46,720
Speaker 1: really our workhorse method. This is the method we've used

407
00:20:46,760 --> 00:20:49,760
Speaker 1: to find a lot of planets recently. And even though

408
00:20:49,800 --> 00:20:53,080
Speaker 1: you can't see every planet, you can do calculations, you

409
00:20:53,080 --> 00:20:55,399
Speaker 1: can extrapolate. You can say, well, if I've seen a

410
00:20:55,440 --> 00:20:57,800
Speaker 1: bunch of them, I know how likely it is for

411
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Speaker 1: everything to be lined up perfectly right for me to

412
00:21:00,000 --> 00:21:02,359
Speaker 1: see it, So I can estimate how many solar systems

413
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Speaker 1: are there out there that aren't lined up perfectly, and

414
00:21:05,200 --> 00:21:08,520
Speaker 1: you can make guesses about those planets. So it's pretty effective. Yeah,

415
00:21:08,560 --> 00:21:11,040
Speaker 1: and there's a big telescope in space that's doing most

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Speaker 1: of this right exactly. The Kepler Telescope is basically launched

417
00:21:14,280 --> 00:21:16,800
Speaker 1: just to do this and so it's just like churning

418
00:21:16,800 --> 00:21:19,639
Speaker 1: out these candidates. And you know, in the beginning it

419
00:21:19,760 --> 00:21:21,479
Speaker 1: was rare. We had like one or two and they

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00:21:21,520 --> 00:21:24,320
Speaker 1: had like special fantasy names. And now there are thousands

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00:21:24,320 --> 00:21:27,000
Speaker 1: of these things and more discovered every week, and so

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00:21:27,119 --> 00:21:29,240
Speaker 1: now it's like a statistical game. Now we're able to

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Speaker 1: ask questions like how unusual is Earth? Or how weird

424
00:21:32,760 --> 00:21:34,800
Speaker 1: is it to have a hot jupiter that's close to

425
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Speaker 1: your star? Or how unusual is it to have nine

426
00:21:37,920 --> 00:21:40,639
Speaker 1: planets or eight planets? So that's really fun. Do you

427
00:21:40,640 --> 00:21:42,639
Speaker 1: think they will run out of names? Like I know

428
00:21:42,720 --> 00:21:47,680
Speaker 1: they use letters and numbers now, like you know, maybe seven, three, nine.

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00:21:47,840 --> 00:21:49,919
Speaker 1: They sort of remind me of license plates, like you know,

430
00:21:50,000 --> 00:21:52,800
Speaker 1: all these names are just like random collections of digits,

431
00:21:53,160 --> 00:21:55,280
Speaker 1: and so I think they can just keep adding digits

432
00:21:55,359 --> 00:21:56,920
Speaker 1: and they're never going to run out of names. Do

433
00:21:56,960 --> 00:21:59,160
Speaker 1: you think when they get to like our two D one,

434
00:21:59,440 --> 00:22:02,280
Speaker 1: the will skip the number just to avoid you know,

435
00:22:02,320 --> 00:22:05,439
Speaker 1: infringing star Wars is right, I'm sure Disney's lawyers have

436
00:22:05,440 --> 00:22:08,040
Speaker 1: already written those letters, all right. So those are two

437
00:22:08,119 --> 00:22:10,720
Speaker 1: good ways to know if there are planets around other stars.

438
00:22:10,760 --> 00:22:12,679
Speaker 1: But there's also kind of a more direct way. Right,

439
00:22:12,720 --> 00:22:16,040
Speaker 1: Like I've seen pictures of planets around other stars, like

440
00:22:16,080 --> 00:22:17,960
Speaker 1: it is possible to kind of look at them, take

441
00:22:18,000 --> 00:22:20,399
Speaker 1: pictures of them. And now we have super powerful space

442
00:22:20,440 --> 00:22:24,320
Speaker 1: telescopes and clever techniques, you could actually look at fairly

443
00:22:24,480 --> 00:22:28,880
Speaker 1: nearby stars and see light off of those planets directly.

444
00:22:29,119 --> 00:22:33,240
Speaker 1: So we have like direct images, actual pictures from those

445
00:22:33,280 --> 00:22:35,800
Speaker 1: solar systems, and not very many of them, just a few,

446
00:22:35,840 --> 00:22:38,160
Speaker 1: because everything has to be like lined up just right,

447
00:22:38,200 --> 00:22:40,240
Speaker 1: and the planet has to be really big and kind

448
00:22:40,240 --> 00:22:42,720
Speaker 1: of far away from its star, and the whole star

449
00:22:42,840 --> 00:22:45,280
Speaker 1: has to be pretty close to us, and you have

450
00:22:45,359 --> 00:22:48,360
Speaker 1: to line up this coronagraph to block the life from

451
00:22:48,359 --> 00:22:50,840
Speaker 1: that star just right. But we've done it, and that's

452
00:22:50,840 --> 00:22:53,840
Speaker 1: pretty exciting. Yeah, but most of what we've done is

453
00:22:53,960 --> 00:22:57,320
Speaker 1: within our galaxy, and it sounds like it's already really

454
00:22:57,359 --> 00:23:01,040
Speaker 1: hard to see planets around other stars within our Milky

455
00:23:01,040 --> 00:23:04,040
Speaker 1: Way galaxy, which is our neighborhood. And so now the

456
00:23:04,119 --> 00:23:07,960
Speaker 1: question is, how could we possibly ever see planets around

457
00:23:07,960 --> 00:23:10,439
Speaker 1: other galaxies. I mean, when we look at a galaxy

458
00:23:10,560 --> 00:23:12,560
Speaker 1: just kind of looks like a fuzzy cloud, like a

459
00:23:12,600 --> 00:23:14,920
Speaker 1: fuzzy collection of stars. Yeah, the problem with all these

460
00:23:14,960 --> 00:23:17,160
Speaker 1: methods is that they start to fail as the star

461
00:23:17,280 --> 00:23:20,480
Speaker 1: gets further and further away. Right, A star that's further

462
00:23:20,560 --> 00:23:24,200
Speaker 1: away wobbles less, and the light that comes from it

463
00:23:24,240 --> 00:23:27,240
Speaker 1: is harder to look at and harder to separate from

464
00:23:27,240 --> 00:23:30,320
Speaker 1: the nearby stars. And so these things start to fail

465
00:23:30,400 --> 00:23:33,200
Speaker 1: as the stars get further away, which is why, for example,

466
00:23:33,240 --> 00:23:36,760
Speaker 1: we haven't even seen planets all through our own galaxy.

467
00:23:36,800 --> 00:23:39,240
Speaker 1: There are parts of our galaxy where we have not

468
00:23:39,400 --> 00:23:42,800
Speaker 1: detected any planets. The furthest planet we've ever seen is

469
00:23:42,840 --> 00:23:46,280
Speaker 1: about twenty seven thousand light years away, whereas the whole

470
00:23:46,280 --> 00:23:49,199
Speaker 1: Milky Ways a hundred thousand light years across. Right, So

471
00:23:49,240 --> 00:23:52,439
Speaker 1: now it seems almost impossible to imagine going to another

472
00:23:52,480 --> 00:23:55,439
Speaker 1: galaxy millions of light years away. But there are some

473
00:23:55,640 --> 00:23:58,560
Speaker 1: very cool techniques people have come up with recently that

474
00:23:58,640 --> 00:24:00,800
Speaker 1: will let us do this way. You said a while

475
00:24:00,840 --> 00:24:04,240
Speaker 1: ago that stars wobble less still further they are away.

476
00:24:04,320 --> 00:24:06,399
Speaker 1: Why is that wouldn't they wobble the same or is

477
00:24:06,440 --> 00:24:09,360
Speaker 1: it just gets lost in the noise. No, you're right, stars,

478
00:24:09,440 --> 00:24:11,800
Speaker 1: if they're far away, they actually wobble the same way.

479
00:24:11,840 --> 00:24:14,600
Speaker 1: It doesn't really matter how far away we are, and

480
00:24:14,680 --> 00:24:16,959
Speaker 1: of course, the sideways wobble is not what we're looking at,

481
00:24:17,200 --> 00:24:19,639
Speaker 1: but the back and forth wabble that's the red shift

482
00:24:19,680 --> 00:24:21,840
Speaker 1: and the blue shift. We could still see that for

483
00:24:21,960 --> 00:24:24,320
Speaker 1: stars that are further away, but they're harder to see.

484
00:24:24,359 --> 00:24:27,000
Speaker 1: You're looking through lots of other stars. They're further away,

485
00:24:27,040 --> 00:24:29,600
Speaker 1: they're more dim, and so it's just harder to study

486
00:24:29,600 --> 00:24:32,000
Speaker 1: these things that are further away. It's a harder to

487
00:24:32,080 --> 00:24:34,600
Speaker 1: make out the wiggle. Yeah, and which seemed almost impossible

488
00:24:34,680 --> 00:24:37,399
Speaker 1: to do this with stars in another galaxy, just because

489
00:24:37,440 --> 00:24:41,479
Speaker 1: it's so far away and you know they're probably drowned

490
00:24:41,520 --> 00:24:44,000
Speaker 1: out by all the other stars in that other galaxy.

491
00:24:44,359 --> 00:24:46,159
Speaker 1: But you're saying there, it is sort of possible to

492
00:24:46,200 --> 00:24:48,359
Speaker 1: look at planets there. Yeah. People have come up with

493
00:24:48,440 --> 00:24:50,600
Speaker 1: crazy ideas to do this, and so the sort of

494
00:24:50,800 --> 00:24:53,960
Speaker 1: three ideas that I think are pretty awesome. The first

495
00:24:54,000 --> 00:24:59,000
Speaker 1: one is called gravitational micro lensing, and it also uses gravity,

496
00:24:59,160 --> 00:25:01,159
Speaker 1: but it's not the wa hobble of the star that

497
00:25:01,200 --> 00:25:04,600
Speaker 1: it's using. It's looking to amplify the light of a

498
00:25:04,640 --> 00:25:08,080
Speaker 1: star by another star passing sort of in front of it.

499
00:25:09,119 --> 00:25:11,600
Speaker 1: That's kind of how we look at dark matter, right,

500
00:25:11,640 --> 00:25:13,800
Speaker 1: And that holds to like if we look for that

501
00:25:13,840 --> 00:25:17,000
Speaker 1: kind of lensing effect exactly because mass doesn't just like

502
00:25:17,080 --> 00:25:20,520
Speaker 1: create gravity, it actually bends space. And so if something

503
00:25:20,640 --> 00:25:24,239
Speaker 1: passes between us and another object, it will bend the

504
00:25:24,320 --> 00:25:27,480
Speaker 1: space between us and that object. So the light from

505
00:25:27,520 --> 00:25:30,880
Speaker 1: the object in the background gets distorted, just like if

506
00:25:30,920 --> 00:25:33,560
Speaker 1: you had a lens in the sky, but now it's

507
00:25:33,560 --> 00:25:37,240
Speaker 1: a gravitational lens. It's bent space, so it changes a

508
00:25:37,359 --> 00:25:39,280
Speaker 1: path of light. But you can use all of your

509
00:25:39,320 --> 00:25:42,000
Speaker 1: intuition for how a lens works to understand how a

510
00:25:42,000 --> 00:25:45,000
Speaker 1: gravitational lens work. The principles the same, even though the

511
00:25:45,040 --> 00:25:48,000
Speaker 1: bending mechanism is different. So what happens here is you

512
00:25:48,040 --> 00:25:50,800
Speaker 1: have a star in the background, and then some star

513
00:25:50,880 --> 00:25:54,080
Speaker 1: in the foreground passes between you and that star, and

514
00:25:54,200 --> 00:25:56,840
Speaker 1: as it passes right through that line between you and

515
00:25:56,880 --> 00:25:59,720
Speaker 1: the background star, it creates this lensing effect and it

516
00:25:59,800 --> 00:26:03,760
Speaker 1: just dorts the background star. That's cool, that's gravitational micro lensing.

517
00:26:04,200 --> 00:26:07,800
Speaker 1: But if there happens to be a planet around the

518
00:26:07,840 --> 00:26:11,360
Speaker 1: star that's doing the lensing, then as the planets going

519
00:26:11,400 --> 00:26:14,000
Speaker 1: around the star, it will change how that lens works,

520
00:26:14,040 --> 00:26:16,680
Speaker 1: and so it will sort of like distort the distortion

521
00:26:16,800 --> 00:26:20,120
Speaker 1: in a particular way, So it changes how the background

522
00:26:20,160 --> 00:26:24,880
Speaker 1: star looks like there'll be a wiggle in the lensing basically, right,

523
00:26:24,960 --> 00:26:28,600
Speaker 1: like the lensing effect will be wiggly. Yeah, exactly, Just

524
00:26:28,640 --> 00:26:30,119
Speaker 1: like if somebody stands in front of you in the

525
00:26:30,119 --> 00:26:32,280
Speaker 1: movie theater and blocks your path, if they have like

526
00:26:32,320 --> 00:26:35,080
Speaker 1: a little toddler running around them the whole time, they'll

527
00:26:35,119 --> 00:26:38,320
Speaker 1: create a different shadow, right, And so it's the same idea.

528
00:26:38,480 --> 00:26:40,640
Speaker 1: And if the parent is like, you know, chasing after

529
00:26:40,680 --> 00:26:43,840
Speaker 1: the child, you would you would notice that from the lensing, Yeah,

530
00:26:43,920 --> 00:26:46,520
Speaker 1: you would notice that. So it changes the pattern of

531
00:26:46,600 --> 00:26:49,760
Speaker 1: the brightening and the fading that you get from gravitational lensing,

532
00:26:49,760 --> 00:26:52,120
Speaker 1: and it doesn't in a particular way. You can even

533
00:26:52,200 --> 00:26:54,639
Speaker 1: enhance it, right, You can get like a flare from

534
00:26:54,680 --> 00:26:57,080
Speaker 1: this planet if it's just in the right spot to

535
00:26:57,160 --> 00:27:00,679
Speaker 1: exaggerate and enhance the light of the background are And

536
00:27:00,720 --> 00:27:03,119
Speaker 1: so this is pretty cool, yeah, but you still need

537
00:27:03,160 --> 00:27:06,720
Speaker 1: a background star to sort of see and be able

538
00:27:06,760 --> 00:27:09,200
Speaker 1: to like see the life from it and be able

539
00:27:09,240 --> 00:27:10,800
Speaker 1: to tell it a part. Can we do that? And

540
00:27:10,840 --> 00:27:13,680
Speaker 1: with stars and other galaxies, like can we see individual

541
00:27:13,720 --> 00:27:17,479
Speaker 1: stars in like Andromeda? You can't always see individual stars.

542
00:27:17,520 --> 00:27:20,000
Speaker 1: But you're right, you need something in the background. It's

543
00:27:20,000 --> 00:27:22,720
Speaker 1: not critical that you have just one star in the background, right,

544
00:27:22,880 --> 00:27:25,199
Speaker 1: You just need some source of light. And then you

545
00:27:25,240 --> 00:27:27,040
Speaker 1: need to have a model for how that light will

546
00:27:27,080 --> 00:27:30,520
Speaker 1: be distorted by a foreground object. And so if you

547
00:27:30,560 --> 00:27:32,520
Speaker 1: have some sort of source in the background, you can

548
00:27:32,600 --> 00:27:35,520
Speaker 1: mimic you can model how that light would be distorted

549
00:27:35,520 --> 00:27:37,880
Speaker 1: by gravitational lensing, even if it doesn't just come from

550
00:27:37,880 --> 00:27:42,200
Speaker 1: one star, even if it comes from like a background galaxy. Interesting, okay,

551
00:27:42,200 --> 00:27:44,359
Speaker 1: So then the star we want to measure would be

552
00:27:44,400 --> 00:27:46,400
Speaker 1: in another galaxy, and now we need like a light

553
00:27:46,440 --> 00:27:49,719
Speaker 1: source behind that other galaxy, behind that star in the

554
00:27:49,760 --> 00:27:53,080
Speaker 1: other galaxy, or in or outside the galaxy. It doesn't

555
00:27:53,119 --> 00:27:54,639
Speaker 1: have to be in that other galaxy. It can be

556
00:27:54,720 --> 00:27:57,840
Speaker 1: like in another galaxy, even behind it, just anywhere behind

557
00:27:57,880 --> 00:27:59,720
Speaker 1: the star that we want to look at. We need

558
00:27:59,720 --> 00:28:02,560
Speaker 1: this perfect lineup of the star we're looking at and

559
00:28:02,600 --> 00:28:05,119
Speaker 1: then the star behind it, so the background star can

560
00:28:05,160 --> 00:28:08,879
Speaker 1: get lensed by the foreground star. So that's a big disadvantage.

561
00:28:08,920 --> 00:28:11,919
Speaker 1: Another big disadvantage is that it usually just happens once.

562
00:28:12,160 --> 00:28:14,719
Speaker 1: It's like a chance thing. These two stars are not

563
00:28:14,800 --> 00:28:17,359
Speaker 1: like usually in a binary system or anything. So it's

564
00:28:17,400 --> 00:28:20,200
Speaker 1: just like by chance that one happens to pass through

565
00:28:20,240 --> 00:28:22,800
Speaker 1: the line of sight to the background star, which means

566
00:28:22,880 --> 00:28:25,840
Speaker 1: you can't repeat it. You just get like one observation,

567
00:28:26,320 --> 00:28:28,359
Speaker 1: and that's kind of hard to like really base the

568
00:28:28,440 --> 00:28:30,920
Speaker 1: claim on if you only see something once. And this

569
00:28:30,960 --> 00:28:33,880
Speaker 1: works with stars in other galaxies, like we can tell

570
00:28:33,960 --> 00:28:37,520
Speaker 1: this wiggling in the lensing for something that far away. Yeah,

571
00:28:37,680 --> 00:28:39,760
Speaker 1: at the end of the program, we'll talk about some examples,

572
00:28:39,800 --> 00:28:42,200
Speaker 1: but it really can work. And the really cool thing

573
00:28:42,240 --> 00:28:44,520
Speaker 1: about it is that it can detect stuff that's pretty

574
00:28:44,600 --> 00:28:48,080
Speaker 1: low mass because the gravitational lensing is very sensitive to

575
00:28:48,160 --> 00:28:50,200
Speaker 1: the mass of the planet, so you can even work

576
00:28:50,200 --> 00:28:53,600
Speaker 1: for like planets down to the size of Mars. Cool.

577
00:28:53,680 --> 00:28:55,840
Speaker 1: All right, Well that's one way. What's another way we

578
00:28:55,880 --> 00:28:58,880
Speaker 1: can look at planets and other galaxies? Another way it's

579
00:28:58,920 --> 00:29:01,240
Speaker 1: more similar to the t ends it method, and that

580
00:29:01,320 --> 00:29:04,040
Speaker 1: you're looking for an eclipse. Here, you have a star

581
00:29:04,160 --> 00:29:06,520
Speaker 1: you're looking for in the other galaxy, and you try

582
00:29:06,560 --> 00:29:09,160
Speaker 1: to find a star that's in a binary system with

583
00:29:09,320 --> 00:29:12,880
Speaker 1: something that's producing really bright X rays like a black

584
00:29:12,920 --> 00:29:15,880
Speaker 1: hole or a neutron star or something. Then the star

585
00:29:15,960 --> 00:29:18,960
Speaker 1: you're looking for sometimes will eclipse that X ray will

586
00:29:19,040 --> 00:29:22,400
Speaker 1: like block those X rays. And this is something we

587
00:29:22,440 --> 00:29:25,160
Speaker 1: can see in other galaxies because X rays are more

588
00:29:25,280 --> 00:29:28,640
Speaker 1: rare than other light and they're really intense, and so

589
00:29:28,720 --> 00:29:32,840
Speaker 1: it's possible to see these things in other galaxies. So

590
00:29:33,240 --> 00:29:36,640
Speaker 1: this lets us see planets around binaries, meaning like solar

591
00:29:36,680 --> 00:29:39,000
Speaker 1: systems with two stars in them. Yeah, exactly, if one

592
00:29:39,040 --> 00:29:41,120
Speaker 1: star that maybe has a planet around it, and the

593
00:29:41,200 --> 00:29:44,200
Speaker 1: other star is a really strong emitter of X rays

594
00:29:44,320 --> 00:29:46,120
Speaker 1: and maybe it's a black hole, maybe it's not a star,

595
00:29:46,440 --> 00:29:48,720
Speaker 1: but some really bright source of X rays, and if

596
00:29:48,720 --> 00:29:51,240
Speaker 1: those two things line up just right so that the

597
00:29:51,280 --> 00:29:54,600
Speaker 1: star you're interested in studying blocks the X rays from

598
00:29:54,680 --> 00:29:56,840
Speaker 1: the other one, then you can see that. You can

599
00:29:56,880 --> 00:29:58,920
Speaker 1: see this sort of like dip in the X ray pattern,

600
00:29:59,240 --> 00:30:00,880
Speaker 1: and we can tell all like you know, if we

601
00:30:00,960 --> 00:30:02,680
Speaker 1: if I look at a galaxy and and I send

602
00:30:02,760 --> 00:30:04,920
Speaker 1: some X rays, I can tell that it's coming from

603
00:30:04,920 --> 00:30:08,000
Speaker 1: a particular star, like we have that resolution. Yeah, because

604
00:30:08,120 --> 00:30:10,440
Speaker 1: X ray emitters are more rare. So there's a lot

605
00:30:10,480 --> 00:30:12,920
Speaker 1: of stars in the galaxy, butN not that many strong

606
00:30:13,120 --> 00:30:15,720
Speaker 1: X ray emitters, and so that makes it less likely

607
00:30:15,720 --> 00:30:18,640
Speaker 1: to happen, but it also makes it easier to separate them, right,

608
00:30:18,680 --> 00:30:21,240
Speaker 1: so there are fewer of these things. Also, X ray

609
00:30:21,240 --> 00:30:23,880
Speaker 1: emitters tend to be really really small. These they are

610
00:30:23,960 --> 00:30:27,760
Speaker 1: very compact objects on black hole or neutron star, and

611
00:30:27,760 --> 00:30:30,280
Speaker 1: so it's more precise. Right, you can like block the

612
00:30:30,560 --> 00:30:35,040
Speaker 1: entire X ray emitter with your star or with your planet. Cool.

613
00:30:35,240 --> 00:30:37,000
Speaker 1: All right, So there's one more way and in which

614
00:30:37,040 --> 00:30:40,560
Speaker 1: we could detect planets in other galaxies. And then let's

615
00:30:40,560 --> 00:30:43,760
Speaker 1: talk about what we've actually found. Have we found planets

616
00:30:43,760 --> 00:30:46,040
Speaker 1: in other galaxies? And what can we know about them?

617
00:30:46,080 --> 00:31:01,360
Speaker 1: But first let's take another quick break. All right, we're

618
00:31:01,400 --> 00:31:05,400
Speaker 1: talking about exo galactic exoplanets. Do I need to repeat

619
00:31:05,440 --> 00:31:07,520
Speaker 1: the exo or can I just say at once like

620
00:31:07,680 --> 00:31:11,160
Speaker 1: exo galactic planets. I think it's like sergeants at arm right,

621
00:31:11,160 --> 00:31:15,000
Speaker 1: it's exo galactic planets instead of planetary exo galactics or

622
00:31:15,040 --> 00:31:20,520
Speaker 1: something that planet planets and other galaxies that are not

623
00:31:20,600 --> 00:31:23,800
Speaker 1: the Milky Way where we're at. And we talked about

624
00:31:23,800 --> 00:31:25,920
Speaker 1: a couple of ways in which we can actually maybe

625
00:31:26,120 --> 00:31:28,920
Speaker 1: see these planets, and you're going to talk about the

626
00:31:29,000 --> 00:31:32,040
Speaker 1: last one. There's one that involves pulsars. Yeah, this is

627
00:31:32,080 --> 00:31:35,000
Speaker 1: my favorite one because it's super crazy in science fiction. Ee,

628
00:31:35,400 --> 00:31:38,680
Speaker 1: and this involves pulsars, right, And so pulsars are neutron

629
00:31:38,760 --> 00:31:42,160
Speaker 1: stars that give off a really really intense beam of light,

630
00:31:42,400 --> 00:31:45,000
Speaker 1: but they're also spinning, and if the beam is not

631
00:31:45,160 --> 00:31:48,480
Speaker 1: perfectly aligned with the spin, then it sort of sweeps

632
00:31:48,520 --> 00:31:51,520
Speaker 1: across the galaxy and gives us a pings. So every

633
00:31:51,520 --> 00:31:53,959
Speaker 1: time it passes across us, we see life from it,

634
00:31:54,040 --> 00:31:56,040
Speaker 1: and then it goes dark, and then it passes across

635
00:31:56,080 --> 00:31:58,560
Speaker 1: from us and it goes dark. These things are crazy

636
00:31:58,640 --> 00:32:02,800
Speaker 1: and amazing, but also because they're super duper precise, Like

637
00:32:02,880 --> 00:32:05,040
Speaker 1: they spin at a very precise speeds and they don't

638
00:32:05,080 --> 00:32:07,320
Speaker 1: seem to change, so we can see like a ping

639
00:32:07,400 --> 00:32:09,520
Speaker 1: from them and then a gap and a ping from them,

640
00:32:09,560 --> 00:32:13,440
Speaker 1: and the time between those pings is very very regular,

641
00:32:14,040 --> 00:32:16,600
Speaker 1: and so that makes them really awesome clocks. And it

642
00:32:16,640 --> 00:32:19,320
Speaker 1: means that we can do things like measure their speed

643
00:32:19,480 --> 00:32:23,240
Speaker 1: relative to the Earth, and in particular we can see

644
00:32:23,320 --> 00:32:26,680
Speaker 1: whether they're moving back and forth because that will change

645
00:32:26,800 --> 00:32:28,840
Speaker 1: how often we get the pin from them. Yeah, so

646
00:32:28,880 --> 00:32:31,280
Speaker 1: it's kind of like the Doppler effect, but instead of light,

647
00:32:31,320 --> 00:32:36,160
Speaker 1: you're looking at the frequency of the pulse are blinking, Yeah,

648
00:32:36,200 --> 00:32:38,960
Speaker 1: exactly when the pulsar is moving away from the Earth

649
00:32:39,000 --> 00:32:41,600
Speaker 1: because it's getting wobbled by a planet that's around the

650
00:32:41,640 --> 00:32:44,600
Speaker 1: pulse are, then the time between the pulse becomes a

651
00:32:44,640 --> 00:32:47,640
Speaker 1: little bit longer. And then when the pulsar swoops around

652
00:32:47,680 --> 00:32:50,760
Speaker 1: it's coming towards the Earth, the time between those pulses

653
00:32:50,920 --> 00:32:53,640
Speaker 1: gets a little bit shorter because it's sort of closer

654
00:32:53,680 --> 00:32:56,280
Speaker 1: to us when it emits the next pulse. So if

655
00:32:56,280 --> 00:32:58,959
Speaker 1: you watch the pulsars timing and you see this wiggle

656
00:32:58,960 --> 00:33:00,920
Speaker 1: where it's like the pulse as they're getting longer and

657
00:33:00,960 --> 00:33:04,000
Speaker 1: shorter and longer and shorter, that tells you that the

658
00:33:04,040 --> 00:33:09,440
Speaker 1: pulsar is wobbling. And because pulsars are so precise, you

659
00:33:09,480 --> 00:33:13,040
Speaker 1: can measure these from pulsars in other galaxies, right, And

660
00:33:13,080 --> 00:33:16,320
Speaker 1: pulsars are very kind of noticeable, right even within the

661
00:33:16,440 --> 00:33:19,360
Speaker 1: Big Gus they are. Yeah, they're very noticeable, and they're

662
00:33:19,440 --> 00:33:21,880
Speaker 1: sort of rare. And that's the disadvantage of this method

663
00:33:21,920 --> 00:33:24,960
Speaker 1: is that, like there aren't that many pulsars and so

664
00:33:25,040 --> 00:33:27,720
Speaker 1: you can't really like find all the planets this way.

665
00:33:27,720 --> 00:33:30,200
Speaker 1: But you know, if you're just looking to find a planet.

666
00:33:30,480 --> 00:33:34,480
Speaker 1: This is one technique. Another disadvantages that pulsars. You know,

667
00:33:34,520 --> 00:33:36,800
Speaker 1: they're the remnant of the death of a star. You

668
00:33:36,880 --> 00:33:39,120
Speaker 1: had a big star which then collapsed and made a

669
00:33:39,160 --> 00:33:42,600
Speaker 1: neutron star. And so it's not always likely that planets

670
00:33:42,600 --> 00:33:45,520
Speaker 1: will like survive this process, that they won't just get

671
00:33:45,560 --> 00:33:48,200
Speaker 1: like blown up when the star goes red super giant.

672
00:33:48,680 --> 00:33:51,040
Speaker 1: And so it's not that common to have pulsars with

673
00:33:51,160 --> 00:33:54,560
Speaker 1: planets around them, but it's possible. So it's a dead

674
00:33:54,600 --> 00:33:57,440
Speaker 1: star spinning really fast and hopefully it still has a

675
00:33:57,480 --> 00:34:00,680
Speaker 1: planet circling around it. That's power all enough to make

676
00:34:00,720 --> 00:34:03,600
Speaker 1: it wiggle, yeah, noticeably, And then then we could maybe

677
00:34:03,800 --> 00:34:05,880
Speaker 1: tell if there's a planet. But but again we couldn't

678
00:34:05,920 --> 00:34:08,279
Speaker 1: tell anything about the planet, could we. Well, we could

679
00:34:08,280 --> 00:34:10,120
Speaker 1: tell that if there's life on that planet, it mus

680
00:34:10,160 --> 00:34:12,680
Speaker 1: have had a really good sunscreen because it survived a

681
00:34:12,840 --> 00:34:16,040
Speaker 1: very traumatic event. Right, So it's not their on their

682
00:34:16,120 --> 00:34:21,400
Speaker 1: underground bunkers with their conditioning, yeah exactly, watching TV shows, yeah,

683
00:34:21,480 --> 00:34:24,160
Speaker 1: their Netflix and chilling on that planet. Yeah. Well these

684
00:34:24,160 --> 00:34:26,239
Speaker 1: are all cool ways. I guess the question now is

685
00:34:26,280 --> 00:34:29,040
Speaker 1: do they work? Have they worked? Have we actually found

686
00:34:29,600 --> 00:34:32,560
Speaker 1: planets with them? So what do we know, Daniel, have

687
00:34:32,600 --> 00:34:35,279
Speaker 1: we found planets in other galaxies? So we actually have

688
00:34:35,440 --> 00:34:38,719
Speaker 1: seen planets in other galaxies, which is so much fun

689
00:34:38,760 --> 00:34:41,840
Speaker 1: to say, and to know that we've achieved this huge

690
00:34:41,920 --> 00:34:45,520
Speaker 1: breakthrough in terms of our like actually factual knowledge about

691
00:34:45,560 --> 00:34:48,480
Speaker 1: stuff going on super duper far away. Right, and by way,

692
00:34:48,520 --> 00:34:52,319
Speaker 1: you mean like the Royal weed. I mean we've been

693
00:34:52,560 --> 00:34:55,680
Speaker 1: me sitting on my couch reading news articles about astronomers

694
00:34:55,719 --> 00:34:58,560
Speaker 1: doing the actual work. You're like, I did that, We

695
00:34:58,640 --> 00:35:02,279
Speaker 1: did that, we could It's like quantum mechanics, right, what's

696
00:35:02,280 --> 00:35:04,640
Speaker 1: the point of doing science if nobody's reading your papers?

697
00:35:04,680 --> 00:35:08,879
Speaker 1: And so I'm participating just by reading their papers. Does

698
00:35:08,920 --> 00:35:12,719
Speaker 1: the paper exist if nobody ever reads it? Exactly exactly,

699
00:35:12,840 --> 00:35:15,000
Speaker 1: I'm collapsing the wave function of these papers. All right,

700
00:35:15,040 --> 00:35:17,200
Speaker 1: So we found planets and other galaxy. Yeah, so we

701
00:35:17,239 --> 00:35:19,359
Speaker 1: have to that are sort of like preliminary haven't been

702
00:35:19,400 --> 00:35:23,080
Speaker 1: confirmed that come from gravitational lensing, and these are tough

703
00:35:23,160 --> 00:35:25,640
Speaker 1: because you can't repeat them, and so like it seems

704
00:35:25,680 --> 00:35:27,719
Speaker 1: like a planet, but who can really tell and you

705
00:35:27,760 --> 00:35:30,120
Speaker 1: can't really do any follow up studies. And one that

706
00:35:30,160 --> 00:35:34,640
Speaker 1: seems really pretty solid using the X ray eclipse method. Alright,

707
00:35:34,680 --> 00:35:36,720
Speaker 1: so step us through. What's the first one we found.

708
00:35:36,719 --> 00:35:39,040
Speaker 1: So the first one we found is from this crazy

709
00:35:39,120 --> 00:35:43,920
Speaker 1: system called the twin Quaysar. So remember, gravitational micro lensing

710
00:35:44,200 --> 00:35:47,520
Speaker 1: requires you to have something in the background. Right, you're

711
00:35:47,520 --> 00:35:49,320
Speaker 1: studying a star. You want to know if there's a

712
00:35:49,360 --> 00:35:51,400
Speaker 1: planet around it, but first you have to have something

713
00:35:51,440 --> 00:35:54,719
Speaker 1: behind it that's going to get gravitationally lensed by your star.

714
00:35:55,120 --> 00:35:58,240
Speaker 1: So it turns out that there's a quasar super duper

715
00:35:58,280 --> 00:36:01,160
Speaker 1: far away. Remember, a quays are is basically just a

716
00:36:01,320 --> 00:36:04,799
Speaker 1: huge source of light. It's very bright. It's probably the

717
00:36:04,840 --> 00:36:07,319
Speaker 1: accretion disk of a black hole, and all that gas

718
00:36:07,480 --> 00:36:09,160
Speaker 1: is really hot and giving off a lot of light,

719
00:36:09,200 --> 00:36:12,120
Speaker 1: so they're some of the really brightest sources in the galaxy.

720
00:36:12,480 --> 00:36:16,120
Speaker 1: And right between us and this quasar is another galaxy.

721
00:36:16,600 --> 00:36:19,120
Speaker 1: So if the quays are really far away, and between

722
00:36:19,200 --> 00:36:22,319
Speaker 1: us and the quasar is a galaxy that's right between it,

723
00:36:22,640 --> 00:36:26,880
Speaker 1: and it's gravitationally lends that quasar into two pieces, so

724
00:36:26,920 --> 00:36:30,400
Speaker 1: we see basically two copies of this quasar split. So

725
00:36:30,480 --> 00:36:33,480
Speaker 1: it's called the twin quasar because it's already sort of

726
00:36:33,680 --> 00:36:37,560
Speaker 1: constantly being gravitationally lens in two bits, Right, and we're

727
00:36:37,560 --> 00:36:40,560
Speaker 1: pretty sure it's not two quasars. We're pretty sure that

728
00:36:40,640 --> 00:36:43,799
Speaker 1: it's the same, but it's just a lens distortion that

729
00:36:43,880 --> 00:36:46,920
Speaker 1: makes it look like they're twins. Yeah, because they're basically identical,

730
00:36:47,000 --> 00:36:50,359
Speaker 1: and you can see correlated fluctuations in the two. So

731
00:36:50,440 --> 00:36:53,279
Speaker 1: sometimes you'll see something happen in the A part of

732
00:36:53,320 --> 00:36:55,319
Speaker 1: it and it will also happen in the B part

733
00:36:55,360 --> 00:36:58,160
Speaker 1: at the same time. So you're pretty confident we're seeing

734
00:36:58,160 --> 00:37:01,000
Speaker 1: like two images of the same ways are but we

735
00:37:01,080 --> 00:37:04,040
Speaker 1: can't see the actual galaxy in between, or can we Well,

736
00:37:04,080 --> 00:37:06,200
Speaker 1: what we can do is we can see the effects

737
00:37:06,200 --> 00:37:08,960
Speaker 1: of that galaxy, and so this is exactly what happened,

738
00:37:09,280 --> 00:37:12,279
Speaker 1: is that we saw a fluctuation in one half of

739
00:37:12,280 --> 00:37:15,040
Speaker 1: the twins and not in the other, and we think

740
00:37:15,120 --> 00:37:18,160
Speaker 1: that's an effect of the galaxy that's doing the lensing,

741
00:37:18,200 --> 00:37:20,680
Speaker 1: because it only appeared in one of them, and what

742
00:37:20,760 --> 00:37:22,640
Speaker 1: we saw was like a little dip in the light.

743
00:37:23,200 --> 00:37:27,160
Speaker 1: And this is consistent with some big planet in this

744
00:37:27,320 --> 00:37:31,160
Speaker 1: foreground galaxy, sort of like changing the lensing of the

745
00:37:31,239 --> 00:37:38,960
Speaker 1: quasar behind it. What that seems implausible to me. So

746
00:37:38,960 --> 00:37:42,040
Speaker 1: so we have a point source of light that God

747
00:37:42,160 --> 00:37:45,600
Speaker 1: destroyed it into two by a whole galaxy, and you're

748
00:37:45,600 --> 00:37:48,319
Speaker 1: saying that a tiny little planet in that galaxy can

749
00:37:48,360 --> 00:37:51,759
Speaker 1: affect that lensing. Hmm, that's exactly what they're claiming, And

750
00:37:51,800 --> 00:37:54,960
Speaker 1: again it's hard to confirm, like what they're seeing is

751
00:37:55,080 --> 00:37:58,680
Speaker 1: consistent with that hypothesis, but like it could also be

752
00:37:58,760 --> 00:38:01,360
Speaker 1: other things, right, it could be just like you're changing

753
00:38:01,360 --> 00:38:04,480
Speaker 1: the arrangement of the stars in that galaxy and that

754
00:38:04,600 --> 00:38:08,279
Speaker 1: changes the gravitational lensing, and so it's consistent, you know,

755
00:38:08,360 --> 00:38:11,359
Speaker 1: with the planet, but it's not a confirmed observation, right,

756
00:38:11,400 --> 00:38:14,520
Speaker 1: because you're saying that the whole galaxy is wiggling because

757
00:38:14,520 --> 00:38:16,759
Speaker 1: of this one planet. Is that what you're saying the

758
00:38:17,239 --> 00:38:20,240
Speaker 1: whole galaxy is shaking because of this one planet going around.

759
00:38:20,360 --> 00:38:22,919
Speaker 1: We're saying that the light from the quaysar is going

760
00:38:22,960 --> 00:38:25,840
Speaker 1: through that galaxy in a way that's sensitive to how

761
00:38:25,880 --> 00:38:29,080
Speaker 1: that planet is moving. And this would be a big planet,

762
00:38:29,320 --> 00:38:31,160
Speaker 1: so it would have to be large to affect this.

763
00:38:31,560 --> 00:38:34,160
Speaker 1: But yeah, you know, the photons that we're seeing our

764
00:38:34,280 --> 00:38:37,200
Speaker 1: gravitational lens by that galaxy, and we're saying that it

765
00:38:37,239 --> 00:38:39,960
Speaker 1: would be changed by the motion of this planet. But

766
00:38:40,000 --> 00:38:41,600
Speaker 1: how do you know it is a planet? Couldn't it

767
00:38:41,640 --> 00:38:43,799
Speaker 1: be like a little black hole in that galaxy? Or

768
00:38:43,840 --> 00:38:46,919
Speaker 1: couldn't it be a star or something wiggling? It could

769
00:38:46,920 --> 00:38:48,680
Speaker 1: be yeah, and it could be a rogue planet. Right,

770
00:38:48,719 --> 00:38:50,920
Speaker 1: So we don't really know very much. We just know

771
00:38:51,120 --> 00:38:54,239
Speaker 1: like something happened in this planet between us and the

772
00:38:54,320 --> 00:38:56,839
Speaker 1: quays are so as I said, it's not really like

773
00:38:56,880 --> 00:39:00,720
Speaker 1: a very well confirmed detection of an exo elactic planet.

774
00:39:00,719 --> 00:39:03,640
Speaker 1: It's just like an early candidate, all right. So and

775
00:39:03,680 --> 00:39:05,600
Speaker 1: this was back in ninety six, but we have more

776
00:39:05,640 --> 00:39:08,319
Speaker 1: recent events. Yeah, So then people tried to do the

777
00:39:08,400 --> 00:39:10,839
Speaker 1: same thing for a closer galaxy. They said, well, let's

778
00:39:10,840 --> 00:39:13,759
Speaker 1: look at Andromeda and Drameda is only two million light

779
00:39:13,840 --> 00:39:16,080
Speaker 1: years away. And what they did is they said, what

780
00:39:16,120 --> 00:39:19,120
Speaker 1: would it look like if we had a gravitational micro

781
00:39:19,320 --> 00:39:23,040
Speaker 1: lensing event in Andromeda? Now, Andrameda is pretty close when

782
00:39:23,040 --> 00:39:25,719
Speaker 1: it comes to galaxies, and so you can't make out

783
00:39:25,760 --> 00:39:28,560
Speaker 1: individual stars very well, but you can like make out

784
00:39:28,600 --> 00:39:31,040
Speaker 1: clusters of stars, and you can say, if one of

785
00:39:31,080 --> 00:39:34,960
Speaker 1: the stars in that cluster was gravitationally micro lensed by

786
00:39:34,960 --> 00:39:37,239
Speaker 1: another star, what would it look like? You can sort

787
00:39:37,239 --> 00:39:39,799
Speaker 1: of like calculate what that would look like and say oh,

788
00:39:40,080 --> 00:39:42,120
Speaker 1: you would get a dip or a change in the

789
00:39:42,120 --> 00:39:44,640
Speaker 1: brightness of the star in a certain way. Then they

790
00:39:44,680 --> 00:39:47,120
Speaker 1: looked for that and they saw it in Andromeda. This

791
00:39:47,200 --> 00:39:49,560
Speaker 1: is in two thousand nine. They see this sort of

792
00:39:49,600 --> 00:39:52,360
Speaker 1: like the thing that looks like a micro lensing event

793
00:39:52,440 --> 00:39:55,440
Speaker 1: in Andromeda, and we think it is a planet, Like,

794
00:39:55,480 --> 00:39:57,640
Speaker 1: how big of a planet? If it's a planet, then

795
00:39:57,640 --> 00:39:59,839
Speaker 1: it would have to be like six or seven time

796
00:40:00,120 --> 00:40:02,520
Speaker 1: the size of Jupiter right in order to cause the

797
00:40:02,560 --> 00:40:04,840
Speaker 1: effect that they saw, So that would be a big

798
00:40:05,040 --> 00:40:07,439
Speaker 1: would be a big planet. Isn't that almost a star?

799
00:40:07,600 --> 00:40:10,480
Speaker 1: Like put in something that big collapse into a star. Yes,

800
00:40:10,600 --> 00:40:13,080
Speaker 1: something much bigger than that would turn into a brown dwarf,

801
00:40:13,160 --> 00:40:16,040
Speaker 1: like about ten times a jupiter with the right composition

802
00:40:16,080 --> 00:40:18,960
Speaker 1: would turn to a brown dwarf. About a hundred times

803
00:40:19,320 --> 00:40:21,919
Speaker 1: the massive jupiter would turn into a star would start

804
00:40:21,920 --> 00:40:24,680
Speaker 1: to fuse. So this could still be a planet, but

805
00:40:24,760 --> 00:40:26,439
Speaker 1: we don't really know, and you know, again it can't

806
00:40:26,480 --> 00:40:28,959
Speaker 1: be confirmed. It was a one time thing. We saw

807
00:40:29,000 --> 00:40:32,440
Speaker 1: this one wiggle. It's characteristic, oh, a planet, but that

808
00:40:32,480 --> 00:40:35,440
Speaker 1: doesn't necessarily mean that it definitely was a planet. So

809
00:40:35,480 --> 00:40:38,840
Speaker 1: again it's like it's a candidate it's exciting, but you know,

810
00:40:38,920 --> 00:40:41,279
Speaker 1: it's not the best evidence that we have, right, But

811
00:40:41,440 --> 00:40:44,239
Speaker 1: it turns out that more recently, last year we got

812
00:40:44,320 --> 00:40:48,759
Speaker 1: a pretty good candidate. Was a difficult year, but it

813
00:40:48,840 --> 00:40:52,040
Speaker 1: was a pretty good year for exo galactic planets. Yeah,

814
00:40:52,080 --> 00:40:56,160
Speaker 1: somebody made this X ray eclipse method work. They found

815
00:40:56,400 --> 00:40:59,840
Speaker 1: a pair of stars that are binary system. One of

816
00:40:59,880 --> 00:41:02,560
Speaker 1: them is giving off a bunch of X rays and

817
00:41:02,640 --> 00:41:05,640
Speaker 1: the other one sometimes blocks those X rays, and it

818
00:41:05,760 --> 00:41:08,359
Speaker 1: blocks it in this way that you can tell that

819
00:41:08,440 --> 00:41:10,879
Speaker 1: there's something else going on with this star. The star

820
00:41:11,080 --> 00:41:14,640
Speaker 1: is doing the blocking must have something around it that's

821
00:41:14,760 --> 00:41:18,439
Speaker 1: changing how it's doing that eclipse, and we can see that,

822
00:41:18,719 --> 00:41:21,520
Speaker 1: and we can see the effect on the eclipse, and

823
00:41:21,560 --> 00:41:24,640
Speaker 1: so we're pretty sure that there's a planet around that star.

824
00:41:24,880 --> 00:41:27,719
Speaker 1: And this is in the Whirlpool Galaxy, which is like

825
00:41:27,920 --> 00:41:32,480
Speaker 1: twenty three million light years away in the constellation URSA Major.

826
00:41:33,520 --> 00:41:37,120
Speaker 1: So something is emitting X rays and something is blocking

827
00:41:37,160 --> 00:41:40,960
Speaker 1: it regularly, and we can see the eclipse and then

828
00:41:41,000 --> 00:41:43,600
Speaker 1: we can see variations in that eclipse. Right, if it

829
00:41:43,680 --> 00:41:46,239
Speaker 1: was just an eclipse from another star, you would see

830
00:41:46,239 --> 00:41:48,920
Speaker 1: a regular pattern, but we see a pattern on top

831
00:41:48,960 --> 00:41:52,239
Speaker 1: of that which means there's something orbiting that star changing

832
00:41:52,360 --> 00:41:55,560
Speaker 1: how it's eclipsing it, and from that pattern we can

833
00:41:55,600 --> 00:41:59,200
Speaker 1: tell actually some really interesting information about the planet. We

834
00:41:59,239 --> 00:42:01,719
Speaker 1: think it's like just about the size of Saturn, maybe

835
00:42:01,760 --> 00:42:04,680
Speaker 1: a little bit smaller, and it orbits that other star

836
00:42:04,840 --> 00:42:08,560
Speaker 1: around ten times the orbital radius of the Earth around

837
00:42:08,560 --> 00:42:12,120
Speaker 1: the Sun, so ten au. Wow, that's crazy precise. It

838
00:42:12,120 --> 00:42:14,719
Speaker 1: seems like a lot of detailed information about something so

839
00:42:14,800 --> 00:42:18,160
Speaker 1: far away. Yeah. Well, because we can take repeated measurements, right,

840
00:42:18,200 --> 00:42:20,880
Speaker 1: so we can study these patterns, we can understand the

841
00:42:20,920 --> 00:42:22,840
Speaker 1: period of this thing. We can look at all the

842
00:42:22,920 --> 00:42:25,200
Speaker 1: dips and the flips and the wiggles, and so that's

843
00:42:25,200 --> 00:42:27,479
Speaker 1: what gives you a lot more confidence that this really

844
00:42:27,520 --> 00:42:30,480
Speaker 1: actually is a big object orbiting that star and to

845
00:42:30,560 --> 00:42:33,520
Speaker 1: make these kinds of measurements. So this technique is much

846
00:42:33,600 --> 00:42:37,680
Speaker 1: better than gravitational micro lensing because it allows for repeated observations.

847
00:42:38,280 --> 00:42:41,400
Speaker 1: But I guess these would be planets orbiting weird things

848
00:42:41,520 --> 00:42:43,920
Speaker 1: like maybe not a railar star, but like a black

849
00:42:43,920 --> 00:42:46,319
Speaker 1: hole or a neutron star. Right, Like the source has

850
00:42:46,320 --> 00:42:48,080
Speaker 1: to be something special, Well, it has to be a

851
00:42:48,120 --> 00:42:50,320
Speaker 1: little weird because it has to be in a binary system.

852
00:42:50,520 --> 00:42:52,680
Speaker 1: You can have a pretty normal star with a planet

853
00:42:52,680 --> 00:42:54,239
Speaker 1: around it, but then you have to be in a

854
00:42:54,320 --> 00:42:57,440
Speaker 1: binary system with something that's giving off X rays, so

855
00:42:57,480 --> 00:43:00,160
Speaker 1: you can then eclipse those X rays. So like our

856
00:43:00,280 --> 00:43:03,640
Speaker 1: star wouldn't be visible from the Whirlpool galaxy using this

857
00:43:03,719 --> 00:43:06,760
Speaker 1: technique because our star is not in a binary system

858
00:43:06,760 --> 00:43:09,439
Speaker 1: with a neutron star or with the black hole giving

859
00:43:09,480 --> 00:43:11,600
Speaker 1: off a bunch of X rays right right. So it

860
00:43:11,680 --> 00:43:14,960
Speaker 1: feels like a lot of these really distant methods for

861
00:43:15,040 --> 00:43:19,080
Speaker 1: other galaxies only seem to work in really strange situations. Yeah,

862
00:43:19,080 --> 00:43:20,880
Speaker 1: you know what I mean. Like, we can find planets

863
00:43:20,880 --> 00:43:23,480
Speaker 1: in our galaxy pretty much any star we can sort

864
00:43:23,520 --> 00:43:26,200
Speaker 1: of check to see if it has planets, But in

865
00:43:26,280 --> 00:43:29,640
Speaker 1: other galaxies we have to rely on these weird kind

866
00:43:29,640 --> 00:43:32,640
Speaker 1: of phenomenons or arrangements. It is so far we don't

867
00:43:32,640 --> 00:43:34,840
Speaker 1: have a way to just check all the stars in

868
00:43:34,880 --> 00:43:36,919
Speaker 1: the galaxy. No, we definitely, and even for the ones

869
00:43:36,960 --> 00:43:39,520
Speaker 1: in our galaxy, right, And it comes down to coming

870
00:43:39,600 --> 00:43:41,720
Speaker 1: up with clever ideas. But that's what I love about

871
00:43:41,760 --> 00:43:44,319
Speaker 1: astronomy is that they have to come up with these

872
00:43:44,320 --> 00:43:47,960
Speaker 1: clever ideas. They think, well, this seems impossible. What if

873
00:43:48,000 --> 00:43:50,799
Speaker 1: there was a really weird configuration and this happened to

874
00:43:50,800 --> 00:43:53,200
Speaker 1: be attached to that which would swing around this other thing. Oh,

875
00:43:53,360 --> 00:43:55,560
Speaker 1: then maybe we could figure it out, and then you know,

876
00:43:55,640 --> 00:43:57,680
Speaker 1: then we bootstrap our way up. We figured that out,

877
00:43:57,960 --> 00:43:59,680
Speaker 1: and then we come up with other ways. And so

878
00:43:59,760 --> 00:44:02,919
Speaker 1: it's just an opportunity for creativity. I mean, somebody needs

879
00:44:02,960 --> 00:44:05,279
Speaker 1: to figure out more ways to see these things, because

880
00:44:05,280 --> 00:44:07,919
Speaker 1: there are a lot more planets out there to look at. Yeah,

881
00:44:07,960 --> 00:44:12,279
Speaker 1: there's room for improvement or new technology, or room for

882
00:44:12,360 --> 00:44:16,319
Speaker 1: us actually going to these other galaxies and looking. Yeah,

883
00:44:16,360 --> 00:44:19,279
Speaker 1: of course the direct observation would be fascinating, but that

884
00:44:19,280 --> 00:44:21,359
Speaker 1: would take millions of years, we think, unless, of course,

885
00:44:21,400 --> 00:44:23,440
Speaker 1: you know, we could just build that worm whole highway

886
00:44:23,760 --> 00:44:26,280
Speaker 1: and then we can get to those other galaxies pretty quickly.

887
00:44:26,480 --> 00:44:28,799
Speaker 1: But yeah, there are opportunities out there. This is a

888
00:44:28,920 --> 00:44:32,640
Speaker 1: young field. We only recently saw the first observation of

889
00:44:32,640 --> 00:44:36,120
Speaker 1: a planet around any other star, and so studying planets

890
00:44:36,120 --> 00:44:38,960
Speaker 1: around stars and other galaxies is a whole open field

891
00:44:38,960 --> 00:44:42,080
Speaker 1: out there. So for you enthusiast thinking about school and

892
00:44:42,120 --> 00:44:45,319
Speaker 1: becoming a physicist, this could be your big discovery. There's

893
00:44:45,400 --> 00:44:47,560
Speaker 1: lots of exciting stuff left to do. This could be

894
00:44:47,600 --> 00:44:50,719
Speaker 1: your PhD. That might take millions of years, but you know,

895
00:44:51,800 --> 00:44:54,080
Speaker 1: get a hang in there. Yeah, Unfortunately you can't get

896
00:44:54,080 --> 00:44:56,759
Speaker 1: the posthumous Nobel Prize. So well, I'm gonna wait for

897
00:44:56,880 --> 00:45:00,680
Speaker 1: a new film starting called The Exo Universe Galactic Planets.

898
00:45:01,800 --> 00:45:03,719
Speaker 1: We need for us to be able to type things

899
00:45:03,719 --> 00:45:06,239
Speaker 1: in other universes, and then we'll zoom in on those

900
00:45:06,239 --> 00:45:09,600
Speaker 1: planets will see people snowboarding down weird slopes filled with

901
00:45:09,640 --> 00:45:12,640
Speaker 1: weird kinds of chemical snow. Yeah. All right, Well, I

902
00:45:12,680 --> 00:45:14,799
Speaker 1: guess it's kind of interesting to think about planets and

903
00:45:14,840 --> 00:45:19,040
Speaker 1: other galaxies because it doesn't seem likely that will ever

904
00:45:19,200 --> 00:45:21,239
Speaker 1: visit them, do you know what I mean? Like in

905
00:45:21,320 --> 00:45:23,600
Speaker 1: our galaxy when we see a planet now it's like,

906
00:45:23,640 --> 00:45:27,240
Speaker 1: you know, twenty thousand or twenty seven light years away,

907
00:45:27,280 --> 00:45:30,440
Speaker 1: that's sort of doable for a human colony. But you know,

908
00:45:30,520 --> 00:45:33,000
Speaker 1: other gasy that is really far away, like we may

909
00:45:33,040 --> 00:45:34,960
Speaker 1: never get to those other galgs. No, you're right, and

910
00:45:35,000 --> 00:45:37,600
Speaker 1: it's more about like asking these questions about whether our

911
00:45:37,640 --> 00:45:40,440
Speaker 1: galaxy is typical and whether it's usual. Like when we're

912
00:45:40,440 --> 00:45:43,160
Speaker 1: studying our galaxy, are we getting misled about how the

913
00:45:43,239 --> 00:45:46,319
Speaker 1: universe works? Or is our galaxy like a pretty good

914
00:45:46,600 --> 00:45:49,560
Speaker 1: test case for understanding the whole universe. So it's more

915
00:45:49,600 --> 00:45:53,120
Speaker 1: about like understanding the broader context than actually like finding

916
00:45:53,160 --> 00:45:55,920
Speaker 1: other homes for humanity. Yeah, I guess it would be

917
00:45:55,920 --> 00:45:58,880
Speaker 1: pretty cool to know what those plants are like and

918
00:45:59,320 --> 00:46:01,680
Speaker 1: how many they are are and if we can pretty

919
00:46:01,719 --> 00:46:04,560
Speaker 1: much expect all galaxies to have as many planets as

920
00:46:04,600 --> 00:46:07,160
Speaker 1: we have, because that would be pretty mind blowing. That's

921
00:46:07,160 --> 00:46:09,000
Speaker 1: a big number to hold in your head. But it

922
00:46:09,120 --> 00:46:11,399
Speaker 1: makes a lot more sense than thinking that there are

923
00:46:11,440 --> 00:46:14,719
Speaker 1: no planets in other galaxies or fewer planets in other galaxies.

924
00:46:15,040 --> 00:46:17,600
Speaker 1: Most likely the Milky Way is pretty typical. It's also

925
00:46:17,600 --> 00:46:20,239
Speaker 1: cool to think about maybe there are civilizations in those

926
00:46:20,239 --> 00:46:23,239
Speaker 1: other planets in other galaxies and they're trying to look

927
00:46:23,239 --> 00:46:26,200
Speaker 1: at us. Yeah, I hope. So. Unfortunately, there's nothing really

928
00:46:26,239 --> 00:46:29,400
Speaker 1: weird enough about our start to make it extra visible

929
00:46:29,800 --> 00:46:32,920
Speaker 1: from other galaxies. Right, We're not like eclipsing and X

930
00:46:33,040 --> 00:46:36,120
Speaker 1: ray source or whatever. But maybe physics students in those

931
00:46:36,120 --> 00:46:38,840
Speaker 1: other galaxies have come up with a crazy clever way

932
00:46:39,120 --> 00:46:43,600
Speaker 1: to discover planets in our galaxy. Yeah, stay tuned, let's

933
00:46:43,600 --> 00:46:46,319
Speaker 1: just listen to their podcasts. Yeah, wait, wait, a few

934
00:46:46,320 --> 00:46:50,160
Speaker 1: million years, or maybe it's arriving now like the Star

935
00:46:50,200 --> 00:46:54,400
Speaker 1: Wars movie. Al Right, well, hopefully that gives you something

936
00:46:54,440 --> 00:46:56,280
Speaker 1: to think about when you look at the night sky

937
00:46:56,480 --> 00:47:00,279
Speaker 1: and wonder how many planets there are. Now many people

938
00:47:00,320 --> 00:47:02,480
Speaker 1: are in the Thanks for joining us you hope you

939
00:47:02,520 --> 00:47:04,920
Speaker 1: enjoyed that, and stay safe on the slopes. See you

940
00:47:04,960 --> 00:47:15,239
Speaker 1: next time. Thanks for listening, and remember that Daniel and

941
00:47:15,320 --> 00:47:18,600
Speaker 1: Jorge Explain the Universe is a production of I Heart Radio.

942
00:47:18,960 --> 00:47:21,600
Speaker 1: Or more podcast from my Heart Radio visit the I

943
00:47:21,800 --> 00:47:25,440
Speaker 1: Heart Radio app, Apple Podcasts, or wherever you listen to

944
00:47:25,520 --> 00:47:26,480
Speaker 1: your favorite shows.