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Hey, welcome to Ologies. I'm your Alie Warren the host. Now each week I sit down with an ologist, I ask why do they love what they do? What is your deal? What should we know about it? And this week we cover the whole fucking universe which has existed and it's expanding in your floating in it, and you're made out of particles and matter and forces we don't even understand, and maybe there are multiverses and is this reality? And what are you doing here and does anything matter?
And of course it does. But should you be afraid of wearing bright lipstick or dancing in public? Probably not. No, in the scope of things, and the scope of things is really it's giant. It's called cosmology. Now, if you think that you listen to this episode already because you learn some stuff about beard care and face wash, think again, suckers. That was cosmetology. This week is cosmology, the study of the cosmos. And so when I say this episode is
like everything, it's actually everything. It's the whole universe. It's a lot, it's a lot, it's so much. It's a two parter, it's a two fur So this week we'll get the nuts and bolts of what astrophysics is, and after about an hour you will walk away cocktail party literate on goddamn astrophysics. Kind of. I don't know. I'm learning here with you. Of all the episodes I've done, this was probably the one I need the least about.
So let's learn together, shall we? Part two of this next week are your questions submitted via Patreon and the Ologies Podcast Facebook group. Y'all had good ones. Next week will address them. Now, the etymology of cosmology. Cosmos with a K is the kicky little Greek word for world or order. So cosmology is a study of planets and such, sure, but also why and what and how where? What's huh?
It's the study of what. This week's cosmologist is someone I've had a fawning Twitter fascination with for a while, and I met through a group of science friends I love, known to some as the nerd Brigade or kind of like a gang but with a website. But I was always kind of intimidated by her because she is, in her own words, an academic nomad, and she continent hops while studying particle physics and black holes and gravitational waves,
and she hangs out with Stephen Hawking. So when I met her through friends, I usually just sat at brunch like a barnacle and tried to look away when she caught me staring at her, So I asked her to be on the podcast. She said yes, and I immediately started perspiring. So she came to my apartment. We sat down, and my usual hour interview stretched to almost two, hence the two parter. Hours before she politely reminded me that we were supposed to be meeting people for a movie
and we should stop. I'm so so glad we did this podcast because I got to know her even better as a friend, which, y'all, I'm going to be cheesy
and say it's a true honor. So in this episode, you'll learn about the things that make you you and the stars that exploded to make the things that make you you, and the scale of our existence in space, and what it feels like to be heckled by Stephen Hawking and if this is real life, and if astrophysicists are just like making bullshit up that the rest of us just accept because we're like, man, I don't even
know how to read these equations. So okay. So you'll get at the very least a loose grasp on just the whole of existence and maybe steel yourself to be the biggest you you ought to be, and more importantly, get to know better one of the world's finest voices in cosmology. You know her as astro Katie on Twitter
aka astrophysicist Katie mac. So take me back to defining some stuff because as a layman, as a lay woman over here, a lay human, yes, I don't know that difference between a physicist, an astrophysicist, a particle physicist, an experimentalist, a cosmologist, and an astronomer. I don't know what those are, and I'm either going to have to Wikipedia this or I can have you give me a rundown.
So these things are, they're a little bit like fluid, these definitions. So astronomer is basically somebody who studies space in some way. And usually when people say astronomer versus astrophysicists, usually astronomer is like more on the observational side or sort of describing stuff in space. Astrophysicist is more about like trying to understand how the physics of the thing in space works. So you can be an astrophysicist trying to understand how galaxies form, for example, and so you're
applying physics to this stuff in space. If you're a particle physicist, you're working on like how particle interactions work, so like you know atoms, fasters and things. Large Hadron collider exposon usually I mean the like classic particle experiment, does you take two particles and you smash them together and you see what comes out. Huh, that's what the Large Hadron Collider is doing now.
The LHC. That's what you call the Large Hadron Collider when y'all are tight, So you've maybe heard of it, you kind of know, like it's a thing in Europe, maybe has something to do with atoms. I looked into it. The Large Hadron Collider is located near the France Switzerland border, and it's a circular tunnel. It's over five hundred feet deep in some parts, and it's seventeen miles around. It
is the largest machine in the world. So this thing consists of over twelve hundred magnets and they're cooled to a temperature colder than outer space, and then the magnets accelerate protons to almost the speed of light, and then the protons are bashed together. It's very punk rock, very expense. The LHC was mostly completed in two thousand and eight. Over ten thousand scientists and engineers worked on it. Now in photos it looks kind of like a giant, well
lit subway tunnel, but with less p and rats. If you're like, I can't remember what a proton is because I'm not required to anymore. I'm not in school, don't worry. Neither did I I had to google, like, how does an atom work? I forgot, so I'll brush you up. So matter is stuff, and molecules are some atoms stuck together. Atoms are made of a nucleus, which is a little
cluster of neutrons and protons. Protons have a positive charge, pro electrons have an equal negative charge, and electrons are bebopping zooming around whirling dervish style outside of the nucleus. So the neutrons and protons, which are the ones that are just cuddling in the nucleus, those are made of smaller powder called quarks. And the quarks come in a couple different varieties. So what gives these particles their mass? What are they? Where do they come from? We've got
all these little tiny things that make up matter. Okay, So I heard it explained that there's a field called the Higgs field. It's named after one alive and well Scotsman physicist named Peter Higgs. And how a particle interacts with the Higgs field gives it its mass, kind of like drag and water. So Higgs bosons are particles. They're an excitation of the Higgs field. It's kind of like
a drop of water. Splashing from an ocean. So the Large Hadron Collider smashed protons together to see if they could prove that the Higgs boson exists, and guess what, bitches it does. You're not bitches. Some people call this the god particle because it's so fundamental to all matter in the universe. Does Doctor Higgs like this name? No,
he's an atheist. He thinks it sucks. And the guy who coined did the God particle actually wanted to call it the goddamn particle, but his publisher made him change it in a book. So the Large Hadron Collider. One of the things it does smashes these protons together into smaller things to figure out why matter has mass. There you go. Also, the Large Hadron Collider accidentally has its name spelled wrong on its own website as Large hard
On Collider once would be mortifying. But what if they did it more than once, like twice or five times? That's impossible, is it? Because a search on their site revealed they'd spelled it large hard On Collider one hundred and sixty five times. Thank God particle for that. That's just precious. So whenever you're like, I don't understand this stuff. Maybe I'm not smart enough. Just think someone typed in large hard on collider over one hundred and fifty times
and they built the thing. So how else do people figure this shit out? About very important things that we can't see.
But there are other ways to do particle physics measuring how particles interact with each other, throwing particles at other things, accelerating stuff, and seeing what happens, all of that kind
of stuff. On the experimental side and on the theory side, it's a lot about trying to understand like the fundamental forces of nature, so like how how atoms hold together, how you know particles can change into other particles in certain conditions, how gravity fits into all that, which it doesn't at the moment theoretically, Okay, okay, it's very hard
to get gravity and particle physics to work together. This is kind of yeah, it's it's sort of This may be another topic, but like, this is the reason string theory was invented.
Real quick, What is string theory? Well, in a very quark sized, tiny nutshell, the premise of strength theory is that basic objects are not point like, but they're string like. So a quark might be made of a loop that kind of vibrates and moves around. Every kind of particle is like a different wiggly string. So why does anyone care? Why are people so horny for string theory? Well, number one, it's from the eighties, and maybe this is like the
scrunchy of particle physics. I don't know. More importantly, string theory is a theory that works with both Einstein's general relativity and that mister Einstein pose that what we perceive as the force of gravity is the curvature of space and time. More on that in a minute, and quantum mechanics, which is the physics of the tiniest building blocks that exist. So remember those quirks that made up protons and neutrons? What are those made of? Maybe these stringlike loops of matter.
Every time I hear string theory mentioned, I think of string cheese. I cannot And I was writing and researching this episode, and I found myself on a website like two thirty in the morning learning that string cheese, as we know what, was invented in Wisconsin in nineteen seventy six, and the way they get it to string is to heat it to one hundred and forty degrees fahrenheit, and that aligns all the milk proteins. Also, the first iterations of string cheese were bigger and chunkier and served to
drunks in bars. Should we get back to physics, Okay, I'm.
Sorry, And this is like the big question in physics is that, like, so, there there are a few sort of fundamental forces of nature. Right, there's electromagnetism, and that's like light and you know, like static cling and all of those kinds of things, right, and magnetism. And then there's the weak nuclear force, which has to do with like how particles decay in radioactivity that kind of thing, and how particles can change into other particles under certain conditions.
There's the strong nuclear force, and that holds particles together in the centers of at Okay, and those all kind of make sense together theoretically, like you can write down equations that make those all fit in some way more or less.
When Katie says you can write down equations that make those all fit, I appreciate her being inclusive with the second person, But I cannot write down equations to make those all fit in some way. I cannot do that.
But then there's gravity, and gravity just doesn't follow any of the same rules. It's like it's very hard to put together a theory that includes those the fundamental forces of particle physics and gravity.
So so it's gravity like the bad boy in a teen drama. It's just like it's just not following any rules.
It's weird. It's like like gravity is all about space time, you know, so gravity like, So the theory of gravity that we have is Einstein's theory of relativity, so general relativity. This is the theory of gravity.
Where okay, yeah, heres Einstein. Here's how the universe of which you are a part works.
The basic picture is that you can think of space as this malleable thing, and if you have something that has mass, it creates like a dent in space. It sort of bends space around it, okay, and so other things moving past will respond to that and like fall into that dent. And that's like how gravitational attraction works. You can think of it in this geometric way, okay, and it works really well like geometrically to think of
it like that. But then there are fundamental principles that happen in that like the speed of light, as a limiting factor and all sorts of things like that, so only certain paths things can follow and everything. But then the particle physics stuff, like all the equations of particle physics are done without thinking about gravity because on those scales, like gravity isn't important. It's a really really weak force, okay.
But also like there are the way that the particle physics is is formulated in the standard model of particle physics, which is what we use to talk about all these interactions.
It doesn't have the same like, it doesn't follow the same rules as gravity, Like there are ways in which the whole like speed of light thing is violated in one way that you can formulate how particles move around, which is kind of like there's kind of like there's this way of formulating it where a particle going from point A to point B passes through every possible path on the way between point A and point B, and it's only by by using that idea that you get
the right answer for how that particle is moving in the particle physics point of view, And that doesn't work with relativity. So there are a couple of things like that, where like quantum mechanics and relativity just do not like each other really, And it gets especially problematic when you get to black hole because a black hole is this very like intense gravitational system mm hmm. It's basically a dent in space time that's so deep that like everything
falls into it if it gets close enough. But at the edge of a black hole, the event horizon, you have this weird quantum mechanical thing happening where you can have like particles evaporating off of it, and that sets like a sort of scale of the black hole, and that means there's quantum mechanics happening in a strong gravitational system,
and then just everything breaks. It just goes totally haywire, because if you look at it from a gravitational point of view, like a relativity point of view, you should see nothing at all interesting happening when you when you fall into the black hole, like aside from like you're you're killed by the gravity, right, Like you don't see
like nothing weird happens when you pass the horizon. But from a particle physics point of view, like there there might be like this like firewall, like there might be like a sort of like boundary of intense radiation there because of the way you have to think about how the particle physics works. This is a complicated story, but.
Basically the astrophysics typically is yeah, I'm not explaining it very well, but but basically, like like, basically, when you get to that point when you have a black hole has an evaporation happening where particles are coming off the edge of the event horizon, one way of looking at it says that that that means that whatever you.
Fought through into the black hole, you can't ever find out what it was. That information is destroid. But quantum mechanics, like the particle point of view, says you can't do that, and so there has to be some kind of loophole and then gravity doesn't like that and you just you
just end up with chaos. And so there's this there's this big problem called the black hole information paradox, which has been around forever, and every once in a while somebody's like, oh, I solved it, and then it's really complicated and people don't really understand how that works.
Has anyone actually solved that?
I mean, I so technically I'm just not qualified to know that for sure, because it requires understanding quantum gravity in a way that I do not. But there have been some solutions suggested, but in general there's still a lot of discussion, so I don't know.
Okay, wait, so what does a cosmologist do.
A cosmologist just means you study the universe as a whole, right, so you study maybe the beginning of the universe, the end of the universe, how it changes over time. But you can be a physicist cosmologist or an astronomer cosmologist,
and those are different, and it's culturally different. Like, but the so if you're a physicist, if you hang out with particle physics people and you say you're a cosmologist, then then the implication is that you work on like the beginning of the universe and the forces of nature and maybe the end of the universe something like that.
If you hang out with astrophysicists and you say you're a cosmologist, then you just study things that are really far away, or you study you know, some something you know more fundamental. But like, you can be a cosmologist in astrophysics and you're a cosmologist because you study very very distant galaxies. The reason that counts as cosmology is because that means you're studying the very distant past of the universe.
So there are different flavors of cosmology, but they're all kind of linked, at least in my opinion, by like, oh, where are we? What are we? What are we made of? AKA, it's a branch of astronomy that involves the origin and evolution of the universe. That's a less panicky way to put it.
And so so then you're studying like how the universe has changed over time. So there are kind of different ways of doing it. And I've done all of those different kinds of cosmology, I guess because I've spent my time kind of bouncing back and forth between the particle physics and the astrophysics communities. So I've worked on you know, the Big Bang and like theories of the early universe, and I've worked on distant galaxies and how galaxies form.
And I've worked on black holes and weird stuff like cosmic strings and just all sorts of things.
What is a cosmic string?
A cosmic string is kind of like a sort of line or wiggly line of energy that stretches across the cosmos. Might not exist, probably doesn't exist, but there could be this like whole network of strings. Of like it's kind of like if you think of like a black hole, but you like stretch it out across the whole universe. You get it's kind of like that, what does it do?
What?
It?
So really interesting things. So if you have two cosmic strings and they cross each other they collide, they can like reconnect in a different way. So you can have two cosmic strings that are about to collide and then they like change so that now you have two sort of loops of cosmic strings. They're going into deficite directions, like so they sort of passed through each other by branching off in this weird way.
So cosmic strings may or may not exist. Now, if they do exist, some theorists have used them to maybe sketch out some stuff about time travel. Please figure that out, please fix some stuff, thank you.
And you can make a loop of cosmic string, and then that loop of cosmic string will like wiggle around and make gravitational radiation and disappear into nothingness. And if you have a cosmic string, like if you have a cosmic string between you and some distant galaxy, then you might see two pictures of that galaxy because it like splits the space kind of. It's really cool.
Now, how much do you think about all of this in your day to day life? And like when you're deciding if you should upgrade your rental car and like if you should cut bangs and what happens to your molecules after you die? Like how much do you let this kind of get to your own existence? Ah?
Yeah, somebody asked me that the other day, Like how much do I like get sort of just overwhelmed by these ideas or whatever? It's not very often, Like most of the time this is like this is fun stuff to work on, but like most of this time it feels more like some kind of combination of science fiction and a fun puzzle, you know. So like I'm trying to solve a problem. I'm trying to calculate something and trying to come up with a new idea for how
to do something, and so it's like a puzzle. It's like some kind of neat thing to work out, And I don't think of it as connecting to my own life or existence because it's way far away or way in the past, or you know, probably doesn't exist. Or whatever. Right, But then every once in a while, like I'll be I'll be thinking about this stuff and I'll be like, oh my God, like there's this stuff is out there.
Like I'll be thinking about black holes or gravitational waves or like the inflation period in the early universe or something like that, and I'll be like I'll have to like hold on to something and be like, oh God, because these are huge, like mind bendingly intense forces and massive things and like the kinds of energies and the kinds of like force and just I don't know the explosions and everything. It's just we cannot comprehend this stuff.
I mean, the Earth is really tiny and really unimportant, like in a big way. So, okay, you know there's this there's this famous photograph, the Pale Blue Dot. Yes, huh yeah, So this is a picture that was taken by the Voyager spacecraft.
So the Pale Blue Dot photo was taken on Valentine's Day in nineteen ninety as Voyager one was leaving the Solar System. It was like by by I'm out, and astronomer Carl Sagan said, Oh, let's turn that lens around. Let's take a pick of all of us far away. What do you say, might as well? And it was three point seven billion miles away. It's little galaxy's longest range.
Selfie this photo itself. It looks like you accidentally took like a blurry image of a few Christmas lights and there was like a speck of dust on your lens. Those lights are just a few scattered rays of sun. And someone would have to point out that that dust is our planet is such a tiny speck. And I'll let Carl Sagan put this in context. He's the pro here, that's here.
That's home, that's us on it.
Everyone you love, everyone you know, everyone you ever heard of, Every human being whoever was, lived out their lives the argregate our joy and suffering, thousands of confident religion, ideologies and economic doctrines. Every hunter and forager, every hero and coward, every creator.
And destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every superstar, every supreme leader, every saint and sinner in the history of our.
Species lived there on a motive. Dust suspended in a sunbeam. The Earth is a very small stage in a vast cosmic arena.
Sometimes when I give talks about cosmology, I'll end with this picture, and I'll be like, you know, she's thinking about how vast the universe is and how really insignificant we are. And the insignificant is even deeper than just what you see from that picture, because in that picture you see like there's a whole lot empty space and then there's a little tiny rock. Yeah, and we're on that little tiny rock, right, oh, and there's a lot
of space. But it's even worse than that because because like, not only are we not the center of like the universe or a galaxy or a solicism or anything like that, the matter that we're made of is also really unimportant because because like like just the kind of stuff that we are and that we can understand and interact with,
regular matter is like five percent of the universe. So most of the universe is something called dark energy that we really don't understand, but it's some sort of mysterious stuff that's making the universe expand faster and faster and it's going to take over eventually. And then there's dark matter, which is some kind of invisible matter that is most of what the galaxy is made of, and most of
what all galaxies are made of. So like our galaxy, you know, we think of it as like this pretty disc of stars, but it's actually embedded in this invisible blob of extra stuff that we can't see. And that blob is way bigger than the stuff that we can actually see. So dark matter is like eighty five percent of the matter in the universe or something like that, Oh my god. And then dark energy is like seventy
percent of all of the stuff in the universe. Like so so then we're this like tiny five percent slice and that's just the kind of matter that we can understand, that we can do experiments on, that we can see
or touch or interact with in any reasonable way. And then it's like not only not only are we like a tiny speck of dust on a tiny speck of dust, like who's you know, Like we are so insignificant, Like the universe doesn't even it doesn't even matter that we're like that our kind of stuff is there.
You know, the best thing about this conversation is, yeah, I'm having it with a cosmologist, and like an astrophysicist, but I could also be having the same conversation with any of my college roommates who had like a seven
foot bong in their garage. Astro Physicists and cosmologists get together, yeah, is it just kind of like a round robin of like stoner existentialism, Like because they feel like there's such a fine line, like and then you're either incredibly incredibly smart and thoughtful and knowledgeable about this stuff, or you're just like you've just numbed yourself enough or you allow yourself to think about it, and then and it's like the Bell curve. There's this big white swath of people
who are like I can't even think about it. It's too much, you know.
I mean, so when I do get together with other cosmologists and we talk shop, it's usually very very technical, and so we don't get into this stuff at all, like we're it's it's usually you know, we're just talking about we're talking in a lot of jargon about like some measurement or something, and we're throwing out numbers and we're trying to like figure out like is this a reasonable measurement to make or whatever, Like what kind of plot can we make to to, you know, to illustrate
this point, or what kind of calculation should we do, or like what's the important variable? It would not be
interesting to somebody who is not in the field. So it's really only when I'm talking about people who are not in cosmology, where like I have these moments of like, oh god, you know, but the thing I mean, but it's it's a little bit dangerous to talk about this stuff though, because then sometimes people get the idea that we really are just kind of sitting around making stuff up, you know, like and so then people think like, oh, I can be a cosmologist, Like what if the universe
is shaped like a football?
You know?
And I think that that the sort of disconnect there is that like the ideas themselves, if they're not backed up by the data or by like a very rigorous model,
are really not that important. Like once we have data and we have some kind of unifying theory that says that this is probably the way things are, then it's like super cool, right, But if somebody had said, like, oh, you know, maybe the universe is like this, like we don't really know what to do with that, and it does, it's not really helpful and you.
Can just spitball.
Yeah, yeah, exactly, like like you have to. It has to be connected to something we can test or or write down mathematically or else. It just it's kind of not helpful, which which is, you know, it's a bummer. But but once you do have the sort of mathematical tools and stuff and you can speak that language, you know, then you can get really creative and then you can
just do really fun things. So like I have I have a project I'm working on that has to do with I have a few interesting projects actually, so I have one. So here's one that it could be fun. So it has to do with black holes and galaxies and the bending of space. Okay, So so every time there's a massive object, it bends space around it, and so that means that light when it goes past bends around so like a lens. Like the massive object acts like a lens for light, and so light gets bent around.
So there's this way to study like what galaxies are made of by having a very bright light behind the galaxy, like really far away and looking at how that light like bends around inside that galaxy and like how the light fluctuates as things move and stuff like that, and that's called gravitational micro lensing in this case the kind of thing I'm working on, but the details aren't important, but it's this thing where like the thing that's making
the bright light is also a black hole. Because it turns out when you have a super massive black hole, like billions of times as massive as the sun, those things can be pulling matter into themselves and that matter lights up like a whirlpool of stuff, and it can make this incredibly bright light that you can see like across the universe. And so we use that as like a back light to study this stuff in a more nearby galaxy to find out how many black holes there are in that galaxy.
So black holes make lights sometimes, Yeah, it's supposed to be confusing.
Yeah, it's like I think, I mean, I think it's like it's one of these things that's like the biggest misconception about black holes is that they're dark. Usually they're not, like the ones we know about are usually not dark,
and it's it's yeah, it's because they're not. It's it's because like technically the black hole itself can't be seen, but it's doing so much that it like affects everything around it, and so usually you can see black holes because they're like really destructive and like the stuff is falling into them, kind of like if you if you had a drain at the bottom of a bathtub, uh huh, Like you might not be able to see the drain through like the you know, bubbles or something, but you
can see that there's like a whirlpool of stuff falling in at that point, oh man. And that's how we see black holes in space usually is we see that they're they're pulling in a lot of matter and so they like that matter lights up and so once it goes into the black hole, we can't see it, but it spends a lot of time whirling around really fast.
It's like an intergalactic garbage disposal.
Yeah, yeah, and it can be. It's some of the brightest things in the universe are black holes. We call them quasars when they're when they're the super massive ones and they're pulling matter in like that and and we have so so that's like those are for black holes that are like millions or billions of times as massive as the sun.
And how far away are those pep beats?
All right? Well, Okay, super massive black holes, the ones I was just talking about millions or billions of times the mass of the Sun. Those seem to exist at the centers of pretty much every reasonably sized galaxy we know about at the centers.
Yes, so including ours?
Yes, really, yes, so our galaxy.
Okay, quick note, let's do a few cosmological basics. Our galaxy is Smoky Way, right, And this next analogy I got right off of NASA's Night Sky website, which I think is for children, but it's so helpful. So okay, imagine our Sun. It's one star among hundreds of billions of stars in our Milky Way. Right. So if we shrink the Sun down to smaller than a grain of sand, our little solar system Venus Mercury Earth, all of those would be small enough to fit the whole solar system
in the palm of your hand. Now, on that scale, with our solar system in your hand, the Milky Way galaxy would be the size of North America. And the Milky Way's big. But our next, our neighbor and Drameda galaxy, it's about twice as big as the Milky Way. Scale is important here, I suppose, But at the center of our galaxy there's a black hole. So the Milky Way.
Is like a disc of stars and gas and dusts and stuff, and we're sort of out toward an edge and at the center there's a bulge of stars and gas and nusts, and then in the middle of there's a black hole. It's four million times as massive as the Sun.
I didn't know that.
Do we have a name for it, Yeah, yeah, we have a name for it. We call it Sagittarius a star, okay, which is a silly name. It's because it's the kind of I think it was like I think a radio source, and because it was pulling in some matter and so it was lighting up in the radio a little bit, and so ours is not pulling in very much matter at all, Like very occasionally it'll lead a little blobb of gas and the astronomers get super excited, but like
there's very little happening with it, but it does. It is really big, and it's got a bunch of stars orbiting really closely around it, and so you can actually go online and see like data follow like tracing out the paths of some of these stars, and you can see them like whip around as they go really close to the black hole in their orbits. So some of them have these orbits that they're really far away and they come in really close and they go boom like
that right around the black hole. And so you can figure out exactly like how big it is and where it is by watching these stars go around it really quickly.
So I did a little looking and if you google European Southern Observatory and s AS in SAM too, you'll find this, oh my god, like a rim shot in a basketball game, like yeah, yeah.
Yeah, like that, except it comes back around. You know, it's on an orbit. So yeah, so there's stuff orbiting really close. So that black hole, that one is like, well, let's see, it's eight thousand parsecs away. I don't know how much that is. A parsec is about three something light years. So a light year is how far how far to how far light travels in a year? Right, So light moves very quickly, so that's a very long way. So for example, light travels it takes light eight minutes
to get between the Sun and us. There's a rule of thumb. Actually, if you want to know how far how fast light speed is, it goes about a foot per nanosecond.
A foot per nanosecond. Yes, oh, that's easy to calculate. Yeah, just a punch of zeros, right, yea, just put a zero on it.
Yeah, yeah, it's easy and now, but it's kind of cool because then you can like you can say, like, if somebody is like ten feet away from you, they are ten nanoseconds in the past.
They're ten nanoseconds in the past. Oh man, I'm going to trip out.
So like we're like three nanoseconds apart, right, So.
Weird, it's so weird. It's great though, And I learned this recently and I've already forgotten it, which is embarrassing. The distance between us and the Sun is a certain what is the U?
Oh that's an astronomical unit.
Astronomical unit.
Yeah, that was the distance between us and the Sun.
I just learned that and then completely forgot it all in the span of a couple of weeks.
It's okay, there's no reason to know that stuff.
I want to know a little bit more about when you were a kid. By the time Katie was about ten years old, she was inspired to pursue some form of cosmology, and she was already a fan of British cosmologist and theoretical physicist Stephen Hawking, she was already hip to him. She's like, I know this dude. Now. If you need a quick brush up on him as a person after this podcast, watch the twenty fourteen Eddy Redmain film The Theory of Everything. I'm a cosmologist, what's that?
I study the marriage of space and.
Time, the perfect couple.
Or you can just watch the trailer and start crying like somebody you know. Now, if thinking about living on a dust moat floating in a sunbeam was an inspiration to do what you want to do in life, consider a human who's figuring out the mysteries of the cosmos, doing computations and cracking theories about which I can't even comprehend. The first paragraph of the Wikipedia page Also while living with als, Katie is one of several billion people inspired
by Stephen Hawking. What was it that Stephen Hawking did or what did you How did you become aware of him and how did you kind of absorb what he did? Well?
I'm not sure how I became aware of him. I think that you know, he was on TV every once in a while, and I had A Brief History of Time the book, and I read that and I just like, I don't know, Like I was interested in black holes, and I was interested in like the Big Bang.
The Big Bang theory being that the universe began those thirteen billion years ago with high temperatures and high density it's continued to expand Also note if you google Big Bang theory, all roads lead to Sheldon, so just be cash call it big Bang as far as Wikipedia is concerned.
And so I would read about that stuff. And Stephen Hawking was a big figure in those those areas, and he was doing a lot of science communication and he would visit cal Tech every once in a while. And I was growing up in LA and St. Long Beach, and so I would sometimes, like my mom would take me to see talks by by physicists because I was super excited about these things. And so I remember seeing
talked by him. I remember seeing a talk by Paul Davies, and like, you know, just prominent theorists would give talks sometimes, and somehow my mom would find out about them and take me along because she's she's really into science and science fiction and physics and everything.
Have you gotten to meet have you gotten to meet stupid Hawking.
Yeah. Yeah, So when I was at Cambridge. So I spent a year at Cambridge during grad school, just kind of visiting and working with people on some research. And I was mostly based in his department and my office was like directly below his. Yeah, and we were in the same like research group basically, I mean like like we didn't talk, like we weren't. I wasn't in his research group, but we were in the same as the center for the article cosmology, and like we were both
based there. So there were you know, half a dozen professors who were told to that he was one of them. And I was a grad student visiting and so I would go to all these like you know meetings and the coffee and stuff. And shortly after I was shortly after I started being a visitor there, somebody asked me to do one of the like lunch seminars.
So basically, if you're a physicist and you're visiting another department, you're kind of obligated to give a talk. That's kind of how it works. So they say, hey, can you give a talk. She's like, yeah, I'll give a talk for the Thursday lunch seminar.
So she does it, and it turns out that it was the lunch seminar that like Hawking goes to. I'm getting ready to give the talk, and I see like several of my professors in the audience like looking expectantly at me, and this is when I'm like freaking out. But he wasn't there. Hawking wasn't there. So I was like, it's fine, it's fine, and I'm getting ready to give the talk. And then I hear this like beee pee pee.
Oh my god, my stomach is cramping just hearing this.
And he shows up.
Oh gets so much worse.
Oh god. So I told this story before, but it's it's still it's still like is it makes me like sweat? So so I was I was getting ready to give the talk, and so I start the talk, like I put up the title side, and I was the The topic was primordial black holes, which is a concept that Hawking came up with along with some other people.
Pressure.
Yeah, And as I'm starting, like as I after I introduced the title and stuff, I hear this this voice say and it was his voice, and I was like, and everybody kind of laughed, you know, and I thought maybe he was like thanking me for talking about the thing that he invented, you know, but I don't know, and you can't ask him to elaborate because he's his speech is very like slow. So he uses this machine thing and it just it's very slow.
Attracks his eye movements.
Yeah, well no, not exactly. It tracks there's a little sensor that looks at his cheek and so he kind of winks and that like selects words on this like list and it takes a couple of minutes per words sometimes, right, So you weren't like I couldn't elaborate, Yeah, yeah, so I had, so so I just kept going and then eventually like I heard it again, yes, or later on or I don't know, or just random things as I'm going, And every time, like I'd look at him and I'd
be like, you know, but he would just kind of look blankly at me. And the person who was like taking care of him is the lunch seminar, So the person who was taking care of him like feedium, and she just kind of looked blankly at me, and like I had no idea what was going on, and so I would just kind of pause and then continue because like what am I gonna do?
What was happening here?
Had no idea, and I was so nervous, and like all the professors were there and already one of the other professors had been like asking a whole bunch of really tough questions on like the second slide. So I was already like freaked out.
Just imagine being in this situation. It's a nightmare. It's like the best nightmare ever.
But like I answered the questions and that he seemed to be okay with it. So I finished the talk and Hawking left and he hadn't asked any questions. And I asked one of the seminar organizers, like what what was that? And he was like, oh, well, when he eats, the machine is chewing and it just picks random stuff from like the quick select menu, So nothing to do with you at all. It was just like it was just like here's the you know, here's the most common phrases. Yes, no,
maybe I don't know. I don't think so.
Oh my god, this is like the worst deodorant ad ever. Like this is the most stressful situation you could possibly ever be.
Oh my god, And like they could have told.
Me, yeah, they could have given you every time.
Oh my god, they just like they just didn't mention.
It any word on whether or not he like you talk.
I have no idea.
Oh my god, could you ever tell him that you went into cosmology because of him?
I don't well. So the first time I met him when I was sixteen, oh just by fourteen fourteen, baby baby, I did tell him then that I was a big fan.
So Hawking was at cal Tech and Katie got her mom to drive her and a friend there to hear him speak. And afterward they were walking the same way that he was going. When they were leaving, and she was too nervous to say hi.
I my friend went up to him and said, my friend would like to speak to you.
She had a wingman.
So I went up and said that I was a big fan and I enjoyed his work, and I thanked him, and he said.
Thank you very much.
Oh Now, what happens to you when you get that? Because you're really I mean, I'm not going to fangirl right here, I'll do it in the intro. But you're like a very big voice in science communication, Like you're a very well known astrophysicists, cosmologist. How do you feel when people come up to you and say I was inspired to study this or you've changed my course, Like, what kind of reactions do you get?
It's I mean, it doesn't so it's not I'm not like Stephen Hawking, Like I'm not that level of famous, and I'm not that level of like important in physics and stuff and and you know, so it's it's kind
of a different thing, but I do. You know, sometimes people do like tell me that they like So one of the messages I've gotten a couple of times is a like a teenage girl will say that she didn't think she could do astrophysics, but she really loved it and then she saw what I was saying on Twitter or something, or she saw me speak and then she decided she was going to go for it.
Wow.
So I do get that sometimes, and I like my feelings, don't know what to do with that, but it's really it's really sweet.
And roam in a black hole no feeling here.
I mean, it is really sweet. It's really like rewarding when that happens, and it makes me feel like maybe like this stuff is maybe the stuff I'm doing is worthwhile. When people say stuff like that or like a little kid will sometimes say that they want to be an astrophysicist or something, and they'll be really excited to meet me,
like I was. I was in Raleigh a couple of weeks ago, and I was I was sitting in a cafe and I was wearing my NASA jacket with a little NASA badge on it that I got it JPL.
JPL, by the way, is NASA's Jet Propulsion Laboratory and it's nestled in the Golden Hills of Pasadena, California, and it's responsible for things like rovers on Mars. And according to press materials, JPL's function is to engineer and fabricate cool ass shit. That's like so dope, that's very bold. NASA also do not fact check that part and is not true.
And this little girl came up to me and she was probably like eight or something, and she asked me if I work for NASA, and I said, I don't work for NASA, but I am an astrophysicist and and so we'd like talk a little bit. And she said that she really is into space and stuff, and I was like, well, I'm giving a talk at the museum in a couple of days you can come and hear
my talk. And so she and her mom came to my talk and she asked a question and it was just really sweet, and I was like, oh, what was her question? I think her I think her question was about like what's inside a black hole?
M h, which is a good question, like a bunch of space garbage.
Well, yeah, so it's I mean, that's it's not as straightforward answer really because once stuff goes inside the black hole, it has to go straight to the singularity, and I can't do anything else, and so then does it really exist at that point? Like that's kind of subtle, But anyways, a good question. And apparently, like she was talking about the talk later on and I was like, hey, you know, I inspired somebody.
She's going to be in your department later and give your lunch Shami dumb questions. Explain the singularity?
Oh yeah, yeah, So a singularity is so it comes up in the context of the Big Bang and in the context of a black hole. A singularity is like
a point of infinite density. Okay, Usually in physics, when you have a singularity, I mean, a singularity basically means it's a point where something infinite happens like where things diverge in some way, and usually when that happens in physics, it means you've done something wrong, okay, and it's a sign that the theory is broken and you just can't deal with that because it is none of the none of the theory like really works at a point of infinite anything, Okay.
In the black hole, like the way that black holes are defined and the way that we understand how the gravity works, there really should be a singularity at the center of the black hole and everything has to move toward it. So so the you know, the black hole has this is this thing that like the way you make a black hole go back up.
One, yeah, no, backup, because they're like, where do they come from? What's the deal?
Yeah, So the way you make black holes you take a really massive star and you wait a while millions of years, and the star will explode and the core of the star will collapse on itself. And if it's massive enough, then I mean the reason that the star didn't collapse before is because it had nuclear burning happening.
It was kind of keeping it puffed up, okay, right, and so you had this energy source that's sort of pushing against it, kind of like if you have like a balloon in the air inside is pushing the plastic the rubber out right. When the star explodes, there's nothing to keep it from collapsing under its own gravity. You know, you get to a point where there's you can't do any more nuclear fusion.
So nuclear fusion is when atoms join to become a different kind of atom and they give off energy in the process, like two hydrogens becoming a helium and giving off energy. Now, this happens with atoms up to the size of iron, at which point that fusion starts to take energy.
You can't get any more energy out of those processes because you've gotten to a point where you've just the whole center of the star is iron basically, and it can't go farther than that. And so then you have this like huge chunk of iron that's not being held up by anything, and so it starts to clapse under
its own gravity. Like that stuff just falls in and it has to go toward the center, and it has to keep going toward the center, and it can't go any other direction, and so you end up with this singularity, this point of infinite density. Technically, what is this shape?
Like?
Is it like an ice cream cone that has an infinite tail?
Or what I mean? You can visualize it that way if you think about it in terms of like a two D analog. Like usually when we think of space time, like the pictures are always like a big rub rubber sheet.
The rubber sheet visual is so helpful for comprehending space time. But also when I think of rubber sheets, usually the situation is not comfortable. It's either like an awkward grad school slumber party explanation or some suburban dungeon kink that sounds exasperating at best. But for space rubber sheets, thumbs up.
And you have this big rubber sheet, and you put a bowling ball in one spot and that bends around, and so then when you take your tennis ball and you try and roll it past the bowling ball, it makes a little orbit and falls in rightow. This is the usual visualization for space time. But that doesn't have the right number of dimensions because space is space is three dimensional, and then you can think of time as another dimension, but that's kind of separate.
Mum, why did they call it Scottish cheese?
It's cottage cheese, honey. And I'm not sure the dogs in other countries speak different languages. Yeah, I think so.
Well when we get there.
Well, we've got to fix the car first, but there's someone coming to help us. Is it the man from Geneva. He's from a Viva Oh there's the van.
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I am curious about time is a fourth dimension?
Okay, well we can talk about that.
Okay, I'm sorry I have so many questions.
But anyways, So if you if space is three dimensional, then the way gravity like works on it is that it kind of like pulls space inward toward itself. So like a massive thing kind of pulls space inward toward itself. So in the context of a black hole, it would be like a place where space gets really scrunched up, right, But it's easier to think about it in the two
dimensional case. So it would be like you have your rubber sheet and you pinch a piece of the rubber sheet and you just pull it down and you just keep pulling it down, and it just goes to a point and it's like, you know, forever, and it gets deeper and narrower whatever. Right, So you can think about it like that, But then you think about like a three dimensional analog, and your brain kind of breaks and it's fader. But yeah, so it's basically a place where
space is really supercurved, okay, really super bent inward. And so there's a point. So if you think again about the two D kind of thing the rubber sheet, you can you can still move past, Like if you have your your like little hole that you pulled down on rubber sheet, you can still take your tennis ball and roll it past that and it'll keep going. But if it gets too close, it'll fall in and there's nothing you can do about it, and it'll always go toward
the deepest point. And so that's like there's this horizon this this distance from this from that singularity where if you get closer than that, you will fall in no matter what, and you will just keep going and you can't ever escape. And light itself will fall in too, because light follows the curve of space, and so if space is curved enough, then light will just follow that
curve all the way down. Oh man, So once you know, so you throw flow a flashlight into a black hole like that light never comes out again, It just goes that that light beam. No matter which direction the flashlight is facing, the light beam will bend toward the center.
And what is that danger zone called the event horizon. Okay, that is the event.
Yeah, that's the event horizon. I mean you should probably stay farther than the event event in general, because other bad things can happen to you if you get close to the black hole.
If you listen to Ology's episode one Volcanology and thought jumping into a volcano was intense, like hang on to your butts right now.
I mean, so, for one thing, the most of the most of the ones that we've seen directly with light are pulling in matter, right, and so that means that there's a lot of hot stuff falling into the black hole in the form of a disk, and so that'll radiate you to death if you get too close. And then if you if you get close, if it's a small enough black hole, then when you get close, the tidal forces will kill you. So tidal force is where you have like, it's where you have more more gravity.
The gravity is pulling stronger on part of you than another part. Oh, so like if like if you imagine, you know, you're falling feet first toward a black hole, the gravity goes the strength of the gravity goes up so steeply because it's such a compact, steep thing. Then your feet will be pulled on much more tightly than your head and you'll be stretched out. And it's it's there's a word for it. It's called spaghettification. It's actually called that.
That's honest thing I've ever heard of my life.
Yeah. Yeah, So you have to watch out for spaghetification if you get too close to a black hole. Who the hell, maybe I don't know, I don't know. I mean Hawking uses it, I don't And maybe he came up with it. I'm not really sure.
Oh my god, But of all of the things to call it.
Yeah, it turns you to spaghetti. I don't know, Like that's just what else are you gonna call it? Like it's title disruption, But I love it the most.
Yeah, Spaghnification was indeed coined by Hawking in his book A Brief History of Time, And if you happen to Google image search this you will find a bounty of photoshopped images of astronauts being tapered into space noodles by cosmic forces. I'm so impressed by this astrophysical whimsy.
Yeah, there are a lot of There are a lot of really silly names in astronomy.
Who gets to name this stuff?
Whoever comes up with it? I mean people come up with a name it, but like sometimes the community names it, like the Big Bang. That that was a joke, Like that was the word was a joke, the term the Big Bang. Like somebody came up with the idea that, you know, the universe started small and has been expanding, and somebody was like, oh, the Big Bang, and that it stuck.
No, it was a throwaway.
Yeah, it was like it was mocking.
Did that person get pissed and it stuck?
I'm not sure.
Okay, So English astronomer Fred Hoyle coined the term big bang. It was during a radio broadcast in the late nineteen forties and it was kind of an accident. Now the story is he's so bent that it's stuck, but apparently he denies that. So drama in ms. What in terms of what your output is? You're you're a professor, you give talks, you travel all over the world, Like what is your big goal as a cosmologist? Like do you want to write an encyclopedia about cosmology? Like what's your endgame?
So I'm almost a professor, you are, I'm going to be a professor. Well, I'm going to be an assistant professor starting January first, yay. Yeah, so I'm not quite a professor yet.
So in a matter of days pretty much, Katie will be assistant professor of physics at North Carolina State University. So tweeted her and say, congrats.
So what my goal? I mean? I want to figure stuff out, but I don't have like there's not like one thing where it's like I must solve this problem. I kind of like, uh, just working on whatever fun stuff comes up, which is not what you're supposed to do.
But it's what you like.
It's always what I like. I mean. So the big thing I'm working on right now has to do with dark matter. So dark matter is this invisible stuff, you know, And it's possible that dark matter has this weird property where if you take a dark matter particle and another dark matter particle and you you like, collide them into each other in just the right way, they'll annihilate and
create other kinds of particles. So that's a possibility. And if that's the case, if that's a thing that happens, then it can mess with how the first stars and galaxies form, because those form and like blobs of dark matter, and the formation of those is kind of delicate because you have to get the right balance of the gravity
and the gas and all this stuff. So if dark matter is going and like annihilating all the time, then that sort of messes with that balance, and so it can change the way the first stars and galaxies form, and then we can look for the evidence of that with telescopes. So this is the kind of problem that I like, where you have like a sort of fundamental particle physics problem and then you try and figure out how to look for it. With telescopes.
So what is your work involved. Do you have like a moleskin that's just filled with like gobbledygook equations, or are you working on a computer with data sets like when you're like when you get down to work, what does that look like?
So I do have my muleskin with full of equations over there. I brought it with me, so I have that. I also have a whole bunch of code that I've written to try to solve some of these equations that are in the moleskin. I mean, so the usual thing is like, Okay, you talk to people who work on similar things, and you try and come up with like
what is it how can we answer this question? Or what is a question we can answer with this obser or like what would be a cool thing that might happen that we could find out if it does happen.
So then physicists talk to each other and writes it down and look at papers and write down more equations. And I was kind of surprised to realize how collaborative this could be. I always imagine physicists needed to be like sequestered in a well appointed lab or a classy den to just think clearly, but now there's like a lot of chatting happening.
And then once you figure out like what equations you need to solve and what things you need to calculate, then you then you go to the computer and you write code to calculate those things and to put out numbers and draw graphs, and then you see if you have something interesting or not.
If it all kind of clicks yeah, yeah, and.
You see if like, you know, does this tell us that this is going to be an interesting technique to test the theory or not? And then depending on you know, because this is all theoretical work. Sometimes sometimes you find well, this is just really uninteresting and is going to care, so I'm not going to write it up. Sometimes you're like, well, you know, it turns out you can't measure this thing with this technique, but we should write that down anyway,
because people might have tried otherwise. And then sometimes it's like, oh, we can measure this thing with this thing and that'll be a really interesting result and we'll get a better answer than anybody's gotten before, So we're gonna write it up and be really happy about it.
And then you go toward writing it up and publishing it.
Yeah, yeah, and then and then you write the paper, and then you publish the paper, and then you know, or you send it to the journal, and the journals the editors or the referees are like, yeah, you should do this differently, and so you do that differently, and then eventually it gets published.
What is the craziest paper that you've ever had published? When the title of the craziest paper, because just looking at paper titles is, yeah, so funny to me because they're so specific and wonderful.
I mean, I guess it depends on what you mean. I wrote a paper called known Unknowns of dark Matter Annihilation over Cosmic Time that.
Sounds like the best like Norwegian metal album them Ever, it was like, well, yeah, so that was all about like what we know we don't know about this problem?
Mm hmm. I've calculated a bunch of stuff. I've I had some papers about, uh like axions and and those are theoretical particles that are super cool.
Is there an upper limit to how many words your paper title can be?
Yeah, you don't want to. I mean you kind of wanted to be punchy, right, like like the whole non unknowns thing is I wanted it to be like eye catching.
Right, it's good marketing.
Yeah, yeah, so you got to think about marketing to some degree, and you don't want it to be a long title because people are going to be skimming out.
This part is crazy. It's like trying to buy Beyonce tickets. So the way that people find papers to read is every day, every weekday. The website, it's a r xiv dot org. There's like a hundred new papers about astronomy and physics and math and stuff.
So the way that people find papers to read is every day, every single day, every weekday. The archive website, it's a r xiv is how it's spelled, but we call it the archive. The archive website displays like one hundred papers, new papers about astronomy, and there's just a list and the titles. So there's the titles and the authors and maybe like the abstract depending on how you
read the archive. And if you're a responsible astronomer, then every morning you wake up and you read the archive and you skim the papers and the and the abstracts and you see which ones are relevant to your work, and then you you know open those and read, you know, skim those papers and find out if like they tell you something interesting, you get information. This is how you keep up with the field. It's so much work. It's
like of a lot of work. And if you're somebody who maybe does you know particle theory stuff as well, then there's a whole other archive for like particle theory, and then part of phenomenology, which is more like the phenomenology is like where you try and figure out what you would see in this in the universe that's closer to what I do. So then if you're trying to read particle theory and phenomenology and astronomy, you can get like one hundred and fifty papers or something every day.
It's a black hole.
It's just it's impossible to keep up.
Oh my god.
But anyway, so because of that, you want your paper title to be punchy and eye catching. But the other thing, so there's a this is like so totally inside baseball, but there's there's this ridiculous thing that happens.
So the order of the papers as they appear on the website is determined just by what time they were sent in and after not too long. These are literal geniuses. They were like duck.
There's a cutoff time of like four pm and sometimes on I don't remember which one, where if you get your paper in as close as possible after that time, it will appear at the top of the god. And so there's this you can people have written papers about like the spike insubmission times, where like everybody's trying to get like, for you know, a clock zero zero one second, Like they all want to get it like exactly at that moment so that their paper will be on the
top of the list. Because a lot of people, you know, like they open the archive and then they just get like exhausted by the time they've gone through five papers, and so they don't get to the end of the list. And so there's this ridiculous, like this ridiculous ritual of when you're when you submit your paper to the archive, you're trying like you watch the clock and you try and hit the submit button exactly the right moment.
That makes me so anxious. It's like when someone people comment first on YouTube vation it should.
Be randomized because like it's also been shown that it does matter in terms of like citations.
That's not right, it's not right. Oh my god. Yeah, Oh wait, what was the question that I had right on top of that? It was definitely a dem one. It was definitely a stupid question.
I don't think any questions are stupid, Are you sure? I think these are good questions. These are important questions because like what it doesn't like you know, these are like if you're asking questions about something because you're not an expert in that field, Like you can't be an expert in every field. If I ask questions about entomology,
I'm gonna have no idea what's going on? Okay, But I'm like, I'm still trying to remember what the difference beviews between a bug and not a bug, right, Like, I don't know.
I'll give you some clearance on that, okay. But the problem is is you study the universe? Yes, so could your field be any broader? Like no, no, it could not literally everything.
Yeah, And this can be a problem too, Like when I give talks, I have to be prepared for anything the questions and that used to just freak me out a lot, and now I just feel like like I just have to I have to read as widely as possible, and sometimes I'll be like, I have no idea but like, like, I gave the talk about gravitational waves in Raleigh the other week and one of the questions was, tell me about the Great Red Spot on Jupiter, And I was like,
it's a storm, it's been shrinking. There's a spacecraft looking at it. You should maybe talk to somebody who studies about that.
The Great Red Spot, by the way, that's its actual name. It's a little on the nose. Also, people mix it up sometimes with the Great Dark Spot, which was near Jupiter's northern poul. So y'all call me, let me name some of these things. Also, how did Katie feel about the detection of gravitational waves? This was the Lago project you may have heard about in twenty sixteen.
The detection of gravitational waves by the Lego instrument was probably the biggest discovery in physics in my lifetime.
Damn.
Yeah, that's a big deal. It's a super big deal. I when so the first the first detection was last year sometime. Well, the detection was the end of twenty fifteen and it was announced I guess during twenty sixteen. The announcement was in I don't remember what times when it was or whatever, but it was such that it was going to be two am local time in Melbourne, and so a bunch of us got together and like
had a party in a university department. Like we brought food and booze and like we watched videos and like we took like we took selfies. It was really late, but we were just like we got to see this live, you know. And and there were there were two people in the room who were part of the collaboration, so they they already knew what was going to be done. But the rest of us, like we'd heard rumors, but we didn't know for sure what was what that was
going to be announced. And yeah, it was. It was just a huge party and it was a we were really excited and like we just everybody was like clap and stuff when it happened, and I mean it was it was a huge deal.
Of the way that it was announced was like a press conference from like an awesome eighties movie.
Yeah, ladies and gentlemen, we have detected gravitational waves.
We did it.
I mean, how cute is that? So that was Dave Ritzi. He's a laser physicist and he's director of the Lego Lab, And I love that audio so much. It's just like pure triumph, like the last scene of a Schwarzenegger movie or something. We have detected gravitational waves. It was like the best.
Yeah, yeah, no, I remember that very clearly.
So explain to me why the detection of gravitational waves is such a big deal.
Okay, So, first, gravitational waves are are ripples in this fabric of space time. So you know, the space space can be bent around massive objects. And when massive objects are moving through space, if they're moving in an accelerated way, which could be in an orbit in orbit as a kind of accelerated motion, that creates ripples in this sort of space time fabric, which is kind of hard to
visualize and explain, but it ripples through space. And so like when you have really massive objects moving really quickly, that can make large disturbances relative to other things. I mean, if I wave my hands, I'm making gravitational waves, but like that's not detectable. So so two black holes orbiting each other make really big detectable gravitational waves, especially when they get so close that they're about to merge into
one thing. So you can have two black holes in a binary orbit orbiting each other, and then as they get closer and closer, the signal gets stronger and stronger, you know, the waves get stronger and stronger, and then they merge and that makes this big sort of burst of gravitational waves. And the way that gravitational waves work,
they're not like ripples on a pond. Usually when you see a visualization, it's like ripples on a pond, but that's that two dimensional analog, you know again, And they're not like if you're standing there, the gravitational wave like moves your space that you're in, but it doesn't just like move you up and down. What it does is it stretches and squeezes the space that you're in. So let's say that you're standing there and a gravitational wave comes,
it hits you in the face. What that does to you is it stretches your space a little bit, so you get a little bit taller and at the same time a little skinnier, and then a little bit shorter and a little wider, and like it oscillates back and forth. So as the waves are coming at you, each wave is giving you that that stretch and squeeze, stretch and squeeze, and so it's actually distorting your shape. Oh my god, what is happening.
This is like a big boy and it it keeps like for everything that creates gravitational waves. Is this doing this to us all the time? Micro micro basis?
Yeah, yeah, So the Lego experiment is built to detect these things. So they have two detectors, and each detector is like it's an L shaped thing. Each arm is four kilometers long.
Now, if you've seen photos of this, you might think from a distance, is some shit that we build like on Mars, because there's just this treeless, ocre landscape in the desert. It seems to look lonely in every direction. But no, it's just Washington State.
And they shoot lasers back and forth along these two arms there. They meet at the center and they're measuring. The lasers are just there to measure the length of those arms, basically, and when a gravitational wave comes and hits that detector, it makes one of the arms a little longer while the other one gets a little shorter, and vice versa, depending on the direction and the you
know and everything. So if it does that, then the detector can detect that the length of the arms has changed and then that's the signal, is the changing of the length of the arms and the level on which that happened. So this is four kilometers right, Yeah.
That's about two and a half miles America.
The first detection, when it was detected, the length of that four kilometer arm changed in length by a thousandth the width of a proton.
Oh my god.
Yeah that's a teensy tiny that's really small.
And this was a huge collision.
Yeah, yeah, this was like it was one point three billion light years away, so it's very far. But it was like the black holes were around thirty times as massive as the Sun and they collided, and so it was a pretty strong signal, Like it was a surprisingly strong signal, Like if you actually looked at the data, raw data, like you could see it, which is not usually the case in this kind of field. Usually, like you have to do lots of processing, but like you
can see the signal is very strong. So but yeah, thousands the width of a proton, so that you know, your own height is changing much less than that, right, because you're not four kilometers long, sure.
So I'm getting a little bit not quite as tall and not quite as skinny, and not kind of quite as short as fat as it's not noticeable in a photograph.
Say, yes, yeah, yeah, it's really it's a really subtle effect. But but yeah, so that's the gravitational wave. It's the detection of that change in length, that sort of stretching and squeezing of space time. And each time the black holes, you know, black holes or something collide, you get this kind of like the the wiggles will come faster and
closer together. And so the frequency of this changing of shape is going up, and the amplitude is going up, and so it makes this kind of rising sound if you transmit it, if you change it into sound, it's like a sort of like the like end part is when they collide. And the reason people change it to sound a lot is because the frequency of these waves coming, like how how quickly the stretching and squeezing happens, is
about the same frequency as like sound waves. Okay, so it is kind of audible, Like if you change it to sound, it's kind of audible.
And that was like the the boop heard around the world, right.
Yeah, yeah, it's called a chirp, A chirp, yes, just.
Okay, you ready for this? This is the sound of history. So what does that mean going forward for astrophysicists, And like, how many more have we heard since then?
So there have been oh gosh, I didn't even know the number, like something like five scene now and the most recent, most recent one was was two black holes. But the one before that was the neutrons. There was two neutrons stars and those were a big deal because those when they collided, also created a gamma ray.
Burst gamma ray burst super energetic explosion, so we can't see gamma rays but the pack of punch and a burst.
And so we were able to see the collision from the gravitational waves but also from light and that was a huge deal. And I can talk about that for hours, but it's it's a big deal. The whole thing is a big deal for a bunch of reasons. One is that this, like the existence of gravitational waves was kind of known indirectly because we'd seen systems where like you had two pulsars orbiting each other, So pulsar is a kind of neutron star. A neutron star is like the
core of a dead star. It's so we'd seen things orbiting each other where the changing of the orbit could only really be easily explained by gravitational waves kind of radiating energy away from the orbit, and so the orbit got smaller because gravitational waves were pulling energy away, oh and sort of shrinking that orbit. So so we had indirect evidence the gravitational waves existed, but we'd never seen
them directly. And seeing like directly, like detecting, like feeling the gravitational wave is a huge deal, right, And the gravitational waves were like the last, the last prediction of Einstein's relativity to be confirmed.
Einstein's theory of relativity. Remember, our perception of the force of gravity is a bendy spacetime thing. I'm very paraphrasing a lot.
So he predicted them one hundred years about one hundred years before the first detection was made, So it was it took a long time to see these things, but so it was confirmed that And it's just this incredible laboratory for relativity for physics because by detecting the gravitational waves and looking at the signal, we were able to determine that gravitational waves travel at the speed of light. We didn't know for sure before. That was part of the theory, but we didn't know for sure, so we
figured that out. It told us stuff about how black holes are made, like what black holes are made of, sort of like the properties of black holes, by examining very closely how they come together and merge, how much energy the gravitational wave burst creates, you know, a lot of stuff about about that. And then because now we can we can watch black holes colliding in the distant universe, we can learn about how black holes grow, you know, by when they collide with each other, and that tells
us something about how black holes grow. It tells us something about how galaxies grow. It tells us something about how stars form, because black holes are the end results of stars.
When you were a kid, were you ever hoping that this that we would be able to detect gravitational waves where you like, I've been waiting since I was a little girl.
So so I didn't know a whole lot about gravitational waves when I was a little kid. But there was there was a really beautiful moment during one of the detection of the neutron star collisions when one of the scientists was he was he was talking about the neutron star collision and the neutron stars when they collide, they make a slightly different kind of like chirp sound.
Okay, here's the sound of the neutron stars booping themselves together.
So the black hole one is actually a lot quicker than what I said, But the neutron star one goes like it takes it. It takes a while and it does it. So and there'd been simulations of this for years. I mean, the scientists who was talking about the discovery said that he'd been waiting to hear that sound from nature for twenty years and he just did and it was really touching.
I mean.
So for me, I knew about LEGO because it was it was partly headed by people at cal Tech, and I was an undergrad at Caltech, And so when I was an undergrad there people were talking about a lot and there was there was a famous bet between like Kip Thorn and Stephen Hawking or something.
Kip Thorn, by the way, is a theoretical physicist, the twenty seventeen Nobel.
Laureate about whether or not gravitational waves would be detected by the year two thousand. I started cal Tech in ninety nine, so they were not detected by year two thousand, so that bet was lost. But it was a funny thing because when I first got to cal Tech, they were building LAGO and it was this big deal and everybody's like, we're going to detect gravitational waves. It's gonna be amazing. And then you know, and LEGO is being built,
and I was like, oh, it's any minute now. And then I left cal Tech and I went to grad school and then after a while, I was like, I haven't heard anything about this for a while, you know, And I realized that like they kind they'd kind of like they'd been like, yeah, we're going to detect gravitational waves, and then they kind of got quiet for a while, and I found out later on asked about it, and they were like, oh no, it's advanced.
LIGO was so there were some upgrades over the years from initial LAGO to Enhanced LAGO to advances LAGO. It's kind of like the tall Grande and Venti gravitational wave detectors just then maybe need a little more to get the job done.
Really going to do the detection. The initial LEGO was like maybe it would get lucky, but advanced LAGO will really see something. I'm like really, So, like for a while, I was like, I don't know what I feel like, I don't know if I believe that this is really going to happen. But then you know, as soon as they turned advanced lago on, like within like a week or something, they saw this thing. So that's like they really they really did it. And it's the most like
it's the most precise instrument ever built by humans. I think I read that somewhere. It's like the I mean, you're measuring something so tiny.
It's crazy.
It's it's impossible. I use, it's incredible. How like what went into it in terms of the engineering and you know, just the physics and like they had to they had to correct for things like the like how how much the photon's hitting the mirrors would move them.
Oh my god, Oh my god.
That's a big part of the noise in the signal that's called the photon shot noise. They have to deal with that. Yeah, so stuff like that. I mean, it's it's incredible that they were able to do this.
So can you get the chirp as a ring tone?
I believe you can. You can, I believe so, Yeah, would you get the the neutron whoop? Or would you get the the black hole one? The black hole one, you have to speed it up to make it sound cool, so you can still hear it, but it's more like a like so so in the actual data, it's like that, that's kind of what it sounds like. But then when you when you speed it up, it goes whoop whoop, but it's very quick, whereas the neutron star one, it's like ooop.
I feel like, yeah, I feel like that's the way to go.
Yeah.
Let's say someone is interesting cosmology but doesn't know a lot about it and is intimidated by it. What is the best book to pick up? I actually, and this is that. I don't know if you've ever read this, but I was. I was in Thailand and I was staying in a hut and there was some there was a free book pile, and I picked up a book called Quantum Mechanics Can't Hurt You. This book was actually called Quantum Theory Cannot Hurt You. It's by Marcus Choone
and it's delightful. I found my copy. It's still moldy from a monsoon. It was good, it was very it was very layperson's terms, but I clearly don't didn't retain any of it. But is there a book or a documentary or something that's just a good primer, because like in this episode, there's no way to describe everything, but like, what's a good go to, like astrophysics for dummies? What are we talking here? Is there a pamphlet? Uh?
So I wish I had a really good answer for this that.
It makes me feel like you don't you're winter.
So the thing is like, I don't. I don't read a lot of popular level stuff. And there's a couple of reasons for that.
So number one, she doesn't have much time to read non papers because there's like a billion papers, and when she does, she likes to read about spaceships. Okay too, when something is written for the general public, astro physicists have to take that lay information and kind of back translate it to a more technical version in their head. So it's like if you're a bartender and someone writes she drank a whiskey, but you're distracted wondering a whiskey,
Well it like a bourbon? Is this a single malt scotch? Was it a rye Tennessee whiskey is this on the rocks was in a cocktail? There's so much detail a minute.
I mean, Sean Carroll's written several books that are really good, so take a look at those. There's a physicist Katie Freeze, Catherine Freeze, who's a dark matter theorist like me. Oh, she's a dark menical corismologist, and she's written a book called Cosmic Cocktail and it's all about about dark matter and also like some audibiographical stuff. It's really cool.
What about What about movies? Do you have a favorite or a least favorite movie about space or cosmology?
You're like, could I not answer some of these?
Yes?
Yes, yes, okay, so so favorite yes. So there aren't a lot of movies where I feel like the cosmology, Like cosmology is hard to have as a topic of a movie because it's just too big a topic, and like stuff happens on cosmological time scales, which is like incredibly long times, and so having something happen within a
movie timeframe is really hard. But there's a movie that I really liked for how it portrayed the scientists and it had some cosmology ish stuff in it, So that was sunshine okay, which the science is wrong, just putting that out there. It's about the sun has like burned out or is burning out and they have to fix it, and none of that can happen. All of that's false, All that's fake. But it's done really well in terms of like they have physicists who who acts like a physicist,
and like they have people who talk like scientists. And I kind of just enjoyed it. Okay, so I thought that, and then there's like a monster thing, so anyway, but I thought that was done really well. I really enjoyed gravity. There's also bad physics in gravity in some places, but I thought it was a beautiful movie and it portrayed space very well.
How do you feel about space balls?
I think it was funny. It's been a long time.
Oh hell yes, that was good.
Yeah. Other space movies like The Martian was fun. Interstellar had a very pretty black hole in it.
Okay, that's that you are being very complimentary, and that is duly noted. You are being a very nice person.
The black hole and the wormhole and Interstellar were very beautifully done and done with with proper relativistic equations. It was very clever because what they did is they they had these simulations that are very very difficult and take a very long time on supercomputers, and they gave them to the the the people who do movie graphics, who have really powerful supercomputers, and they're like, no, we need
to do this black hole properly. So they calculated it, and now they got some like papers out of it because the result was such such a good calculation that they were able to get actual science out of the calculation done for the graphics in the movie.
Because movies are better funded.
Then yeah, yeah, yea, so it was a very good move. But but you should you should know that that the black hole in Interstellar, although there are some aspects that are done very faithfully, they did have they did tweak some things, so it actually would look pretty different if we saw an actual black hole in real life. So there are a couple of things that were tweaked that were a bit different.
So, speaking of movies, Katie and I were supposed to go to one after this interview, and we did, but we barely made it. Because this is all really great information. We hadn't even gotten to the rapid fire around of all of your questions, so I asked your questions. We race to the showing and this poor woman had to smuggle a burrito and eat it in the theater. I'm so sorry. By the way, we saw murder on the
Oran Express. It features a very bizarre mustache. I will give it that, So stay tuned the first two parter Anology's history when we resume with your questions, so you now have a solid base, Tune in next week to hear Astro Katie address your questions, including is there a name for the disorientation and panic one feels when considering the vastness of the universe there is Are any of the sci fi movie methods to save the planet plausible? Or are we basically doomed if an asteroid uses us
as a target? Will the universe expand forever? What's the deal with multiverses? Are there aliens? And speaking of your submissions, I wanted to let you know I totally see the reviews you write on iTunes and it's so appreciated. Rating and reviewing and subscribing is free, It takes very little time, and it helps ologies stay up there in the science charts, so more folks know about it. So thank you so much.
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explain these concepts that I thought. And right now, as I record this middle of the night, my neighbors had been blasting techno Christmas pop songs for four hours while I was learning about wormholes. The world feels very surreal. Also, congratulations to anyone who made it to the end of this episode. Man, you stuck it out. I appreciate that. As a special thanks, I'm going to tell you a secret that no one in the world knows. Earlier tonight, I ate cereal. I bought from a gas station and
I loved it. So if you listen to the end of this episode, feel free to holler at ologies or Ali Ward. I'm sure I'll have a new secret for you next week at the very end, when we are back with Katie, Max Q and A. So until then, ask smart people dumb questions because they love it and we're just tiny meat blobs on a dust spec So let's just live. Can we live? Okay? Byebye? Pacadermatology, hobbiology or do zoology, lithology, technology, meteorology and pedatology, ethology, zeriology, elenology,