Ologies with Alie Ward - Cosmology (THE UNIVERSE) Part 1 Encore with Katie Mack

Episode Date: September 5, 2023

Stars. Black holes. THE GAWDANG UNIVERSE. Astrophysicist and cosmologist Dr. Katie Mack (@astrokatie) re-introduces us to this 2017 episode along with some bonus updates on astrophysics, her career, and the book she’s published since we last heard from her. Katie also tells us her most embarrassing moments as a cosmologist, debunks some physicist myths and gives us the nuts + bolts of everything form particle physics to gravitational waves and existential mysteries. Walk away with cocktail party comprehension of everything from the itty-bitty quarks that make you to the neutron stars banging together across the cosmos. More than anything, get perspective about your life on this, our little pale blue dot.Visit Dr. Mack’s website and follow her on Instagram, Twitter, YouTube and TikTokBuy Dr. Mack's new book: The End of Everything (Astrophysically Speaking)More episode sources & linksSmologies (short, classroom-safe) episodesSponsors of OlogiesTranscripts and bleeped episodesBecome a patron of Ologies for as little as a buck a monthOlogiesMerch.com has hats, shirts, masks, totes!Follow @Ologies on Twitter and InstagramFollow @AlieWard on Twitter and InstagramEditing by Steven Ray Morris and Mercedes Maitland of Maitland Audio ProductionsTranscripts by Emily White of The WordaryWebsite by Kelly R. DwyerTheme song by Nick Thorburn

Hey everyone, this is Katie Mac, your friendly neighborhood cosmologist and connoisseur of cosmic catastrophes. It's been a while since I've talked to you on all of these, and a lot of things have been happening. Since that time, I have published a book called The End of Everything, Astrophysically Speaking, which is all about different ways the universe might end and what those would look like, and I've moved to a new place. When I recorded this, I was just about to start a job at North Carolina State University, where I was an assistant professor of physics. And about a year ago, I moved to the perimeter institute for theoretical physics in Ontario, Canada. And there I have a really cool job title, which is the

Hawking Chair in Cosmology and Science Communication. And at the perimeter institute, I continue my research on dark matter, and I work on a number of other early universe kinds of questions, and I do a bunch of public engagement, outreach, things like that. I give a lot of talks, I do radio things, and'm working on a new book which will come out in a couple of years that's about particle physics. So this episode is an episode from 2017, the end of 2017, and a lot has happened in physics since then. In terms of what I talked about on the episode,

there's a bit of an update for the LIGO experiment. At the time, there were just a handful of detections of black holes colliding in other galaxies, which is just amazing. But now there have been something like 90 detections of black holes colliding in other galaxies. There will be some discussion in the episode about gravitational waves that we see from those. Another thing that we talked about is supermassive black holes and what they would look like if you could see them, and in the movie Interstellar there was a simulation of what that would look like. Since then, astronomers have actually seen that. They've actually seen the light from stuff falling into black holes and the black hole shadow that's produced when the light gets eaten by the black holes. So there's an experiment called the Event Horizon Telescope project where astronomers basically linked together telescopes all over the world and created an image of

a couple of supermassive black holes. So yeah, really exciting stuff. Check out those things and I hope you enjoy this little blast from the past of cosmology. Hey, welcome to Allegies, I'm your Ellie Ward, 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 and you're 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 boring 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 listened to this episode already because you learned some stuff about beard care and facewash, think again suckers. That was cosmology. 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-fer. 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 god damn 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 Allergy's Podcast Facebook group. Y'all had good ones. Next week are your questions. Submitted via Patreon and the Oligis Podcast Facebook group, y'all had good ones. Next week we'll address them. Now the etymology of cosmology. Cosmos with a K is the Kiki 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? Huh? It's a study of what This week's cosmologist is someone I've had a falling Twitter fascination with for a while and I met through a group of science friends I love known to some is 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 aren't 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

and 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 steal yourself to be the biggest you you want 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 Mack. So take me back to defining some stuff because as a layman, as a laywoman over here, a lay human, I don't know the difference between a physicist and 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 describing stuff in space. Astrophysicist is more about 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 how particle interactions work. So, Adam Fashers and things, Large Hadron Collider, he exposed on, usually, the classic particle experiment

is you take two particles and you smash them together and you see what comes out. That's what the Large Hadron Collider is doing. Now, the LHC, that's what you call the Large Hadron Collider when you're 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 500 feet deep in some parts, and it's 17 miles around. It is the largest machine in the world. So this thing consists of over 1200 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 expensive. The LHC was mostly completed in 2008, over 10,000 scientists and engineers worked on it. Now in photos, it looked kind of like a giant well lit subway tunnel, but with less

pee 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. Needed it, 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 b-bopping, zoom it around, whirling, derbish 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 particles 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 both on 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 Dr. Higgs like this name? No, he's an atheist. He thinks it sucks. And the guy who coined it the God Particle actually wanted to call it the God damn particle, but has published or 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 Hardon 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, 165 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 150 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 the fundamental forces of nature. How atoms hold together, how particles can change into other particles in certain conditions,

how gravity fits into all that, which it doesn't at the moment, theoretically. It's very hard to get gravity and particle physics to work together. This is kind of, yeah, 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 string 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 80s. And maybe this is like the scrunchy of particle physics. I don't know. More importantly, strength theory is a theory that works with both Einstein's general relativity. And that, Mr. Einstein, posed 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 string-like loops of matter. Every time I hear string theory mentioned I think of string cheese. I can't not. And I was writing and researching this episode and I found myself on a website like 2.30 in the morning learning that string cheese as we know it was invented in Wisconsin in 1976 And the way they get it to string is to heat it to a 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 and 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 are a few sort of fundamental forces of nature, right? There's electromagnetism, there's, 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 atoms. 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 this second person, but I cannot write down equations to make those all fit. I appreciate her being inclusive with this 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 very hard to put together a theory that includes the fundamental forces of particle physics and gravity. So it's gravity like the bad boy in a teen drama. It's just not following any rules. It's weird. Gravity is all about space time. 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. Get ready. Here's Einstein. Here's how the universe of which you're 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 is important. It's a really really weak force. Okay. But also, like there are the way that the particle physics 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 using that idea that you get the right answer for how that particle is moving in the particle physics point of you, and that doesn't work with relativity. So there are a couple of things like that where quantum mechanics and relativity just do not like each other. And it gets especially problematic when you get to black hole because a black hole is this very like intense gravitational system. It's basically a dent in spacetime that's so deep that like everything falls into it if it gets close enough. But at the edge of a black hole they have enhorizon. You have this weird quantum

mechanical thing happening where you can have like particles evaporating off of it. And that sets a 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 fall into the black hole, like aside from like you're killed by the

gravity, but 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, there's like astrophysics typically is. Yeah, I'm not explaining it very well. But basically, like, like, basically when you get to that point, when you have a black hole, it has an evaporation happening where particles are coming off the edge of the event horizon. One way of looking at it says that that means that whatever you thought through into the black hole,

you can't ever find out what it was, that information is destroyed. 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 end up with chaos. And so 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. Yeah. So I don't know.

Okay, wait. So what does a cosmologist do? The 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. So if you're a physicist, if you hang out with particle physics people and you say you're

a cosmologist, then the implication is that you work on 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, something 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 do we made of? A.K.A. It's a branch of astronomy that involves the origin and evolution of the universe. That's a less panicky way to put it.

Oh. And 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 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 if you think of like a black hole, but you like stretch it out across the whole universe.

It's kind of like that. What does it do? So really interesting things. So if you have two cosmic strings and they cross each other, they collide. They can 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 that are going into opposite directions. Like so they sort of pass 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 forget 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 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 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? Yeah, somebody asked me about 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 the time it feels more like some kind of combination of science fiction and a fun puzzle. So 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.

So it's like a puzzle. It's some kind of neat thing to work out. 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 thinking about this stuff and I'll be like, oh my god, like, there's 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 is really tiny and really unimportant like in a big way. So okay, you know there's this there this famous photograph, the pale blue dot. Yes. 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 1990 as Voyager 1 was leaving the solar system. It was like, bye bye, I'm out. And astronomer Carl Sagan said, yo, let's turn that lens around.

Let's take a pic of all of us far away. What do you say? Might as well. And it was 3.7 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 aggregate or joy in suffering, thousands of confident religions, 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 and love, every mother and father, hopeful child, inventor and its plorer, 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 mode of 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, just thinking about how vast the universe is and how really insignificant we are. And the insignificant it's is even deeper than just what you see from that picture. Because in that picture, you see there's a whole lot empty space, and then there's a little tiny rock. And we're on that little tiny rock, right?

Oh, boy. And there's a lot of space. But it's even worse than that, because not only are we not the center of the universe, or a galaxy, or a solace, or anything like that, the matter that we're made of is also really unimportant. Because like just the kind of stuff that we are and that we can understand and interact with, regular matter is like 5% 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 85% of the matter in the universe or something

like that. Oh my god. And then dark energy is like 70% of all of the stuff in the universe. Like so, so then we're this like little tiny five% 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 not only a tiny speck of dust, some tiny speck of dust, like it was, you know, like we are so insignificant, like the universe doesn't even, it doesn't even matter that we're like that are kind of stuff is there, you know? The best thing about this conversation is,

yeah, I'm having a 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 the garage. When astrophysicists and cosmologists get together, is it just kind of like a round robin of like stoner existentialism? Like, because they're feeling 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 for you to allow yourself to think about it. And then it's like, the bell carved, this is big, wide 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 customers, and we talk shop, it's usually very, very technical. And so we don't get into this stuff at all. Like, 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 I have these moments of like, oh god, you know. But the thing, I mean, it's a little bit dangerous to talk about that stuff though because then sometimes people get the idea that we really are just gotta sitin' around making stuff up, you know? And so then people think,

oh, I can be a cosmologist. Like, what if the universe is shaped like a football? And I think that the sort of disconnect there is that 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 like, yeah, yeah, yeah, exactly. Like, like, you have to, it has to be connected to something we can test or write down mathematically, or else it just, it's kind of not helpful. Which is, you know, it's a bummer.

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 a project I'm working on that has to do with, have a few interesting projects actually. So I have one, so here's one that that could be fun. So it has to do with black holes and galaxies and the bending of space. Okay. 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 microlensing 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 supermassive

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 so we use that as like a backlight to study So we use that as like a backlight to study the stuff in a more nearby galaxy to find out how many black holes there are in that galaxy. So black holes make light sometimes? Yeah. Is that supposed to be confusing?

Yeah, it's like, I think it, I mean, I think it's like, it's one of these things. It'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, yeah, it's because they're not, 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,

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 is we see that they're pulling in a lot of matter, and so 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 the supermassive ones, and they're pulling matter in like that. And we have. 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 puppies? All right. Well, okay, supermassive 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 Milky 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 is big, but our next ornate and drama to 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 dust and stuff, and we're sort of out toward an edge. And at the center, there's a bulge of stars and gas and dust, and then at the middle of that there's a black hole that's 4 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 kind of, I think it was like a thing 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 blob 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, 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 orbit. So some of them have these orbits that they're really far away and then they come and 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 is in SAM 2, you'll find this. Oh my god, like a rim shot in a basketball game? Yeah, yeah. Yeah, like that except it comes back around, you know, it's on a orbit. So yeah, so there's stuff Orbiting really close to that black hole that one is like well

Let's see. It's 8,000 parsecs away. I don't know how much that is in light years a parsec is about three something light years So light years how far how far take how far light travels in a year right? So light moves very quickly. So that's a very long way 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 wanna know how fast light speed is,

it goes about a foot per nanosecond. A foot per nanosecond. A foot per nanosecond. Yes. Oh, that's easy to calculate. Yeah. Just a bunch of zeros, right? Yeah. Just put a zero on it.

Yeah. Yeah, it's easy. But it's kind of cool, because then you can say, if somebody is like 10 feet away from you, they are 10 nanoseconds in the past. They're 10 nanoseconds in the past. Oh, man, I'm going to trip out. I'm just going to say we're like three nanoseconds in the past. Oh man, I'm gonna trip out. I'm just like we're like three nanoseconds apart right now. That's so weird.

That'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 you? Oh, that's a astronomical unit. Astronomical unit. Yeah, that's the distance between us and the sun. I just learned that and then completely forgot it all in this fan of a couple of weeks.

And so, 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 10 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 the student. Now if you need a quick brush up on him as a person after this podcast watch the 2014 Eddie Redmain film The Theory of Everything. Man of Cosmologist. What's that?

I study the marriage of space and time. The perfect couple. Or you can just watch the trailers start crying, like somebody you know. Now if thinking about living on a dust moat, floating in a sunbeam, wasn't inspiration to do what you want to do in life, Consider a human who is 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,

K.D. 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? I'm not sure how I became aware of him. I think that 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, I was interested in black holes and I was interested in the big bang. The big bang theory being that the universe began those 13 odd billion years ago with high temperatures and high density and it's continued to expand. Also, note, if you google big bang theory, all roads lead to sheldon. So just becash, 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 areas, and he was doing a lot of science communication. And he would visit Caltech every once in a while. And I was growing up in LA and sort of long beach. And so I would sometimes, like, my mom would take me to see talks by my physicist because I was super excited about these things and so I remember seeing talk 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 really into science and science fiction and physics and everything. Have you gotten to meet Stephen 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're in the same as the center for the article cosmology and like we're both based there. So there were, you know, half a dozen professors who were involved with that. He was one of them and I was a grad student visiting. And so I would go to all these meetings and the coffee and stuff. And shortly after I started being a visitor there, somebody asked me to do one of the 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 I'm like this one I'm like freaking out but he but he 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 beep beep, beep, beep. Oh my god, my stomach is cramping, just hearing this and he shows up,

oh, get so much worse. Oh god, so I told this story before, but it's still, it still like, it makes me like sweat. So 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 topic was Promordial Black holes, which is a concept that Hawking came up with along

with some other people. And pressure. Yeah. And as I'm starting, like, as I, after I introduced the title and stuff, I hear this voice say, thank you. 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 his his speech is very like slow so he uses this machine thing and it just it's very slow it tracks tracks 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 minutes per word sometimes. Right so you weren't like I couldn't be like yeah yeah so I had so so I just kept going. And then eventually, like I heard it again, or later on, or, or, or just random things as I'm going. And every time 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 was a lunch seminar. So the person who was taking care of him was like feeding him

and she just kind of looked blankly at me and like, I had no idea it was going on. And so I would just kind kinda pause and then continue. I guess like, what am I gonna do? Was he heckling you? What was happening here? I 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 and a 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 I answered the questions, and 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 was that? And he was like, oh well, when he eats, the machine picks up on his chewing and it just picks random stuff from the quick select menu.

Oh, so, and nothing to do with me at all. It was just like, here's the most common phrase, 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 all the hints every time. Oh my god. They just didn't mention it.

Any word on whether or not he liked your talk? I have no idea. Oh my god. Oh my god. But like, they just didn't mention it. Any word on whether or not he liked your talk? I have no idea. Oh my god. Did 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 16, oh, just my 14, 14.

Baby, baby. I did tell him then that I was a big fan. So Hawking was at Caltech and Candy 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. My friend went up to him and said,

my friend would like to speak to you She had a wing man So I went up and said that I was a big fan and I enjoyed his work and I thanked him and he said Now what happens to you when you get that because you're really I mean I'm not gonna fan girl right here I'll do it in the intro, but you're like a very big voice and science communication You're like you're a very well-known Astrophysicist cosmologist. What 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 you know so 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 gonna 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- Throw one of black hole. I mean, it is really sweet. It's really, like, rewarding when that happens.

And it makes me feel like maybe like the 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 in Raleigh a couple weeks ago and 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. I also do not fact check that part. It 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 a NASA physicist.

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, what was your question? I think her, I think her question was about like what's inside a black hole, which is a good question.

You're like a bunch of space garbage. Well, yeah, so it's, I mean, it's not a 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 it does it really exist at that point, like, that's kind of subtle. But anyway, it was a good question. And apparently, like, she was talking about the talk later on and I was like, oh, yay! I inspired somebody. She's going to be in your department later and give a talk with your lunch Jamie Explain the singularity. Oh, yeah, yeah, so 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, where 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 there's none of

the, another theory, like really works at a point of infinite anything. In the black hole, 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. Everything has to move toward it. So the black hole has this thing that, like, the way you make a black hole, you're going to get back up a little bit. Yeah, no, back up, because they're like, where do they come from? What's the deal?

Yeah, so the way you make a black hole is 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 was because it had nuclear burning

happening. It was kind of keeping it puffed up. You had this energy source that's sort of pushing against it, if you have a balloon in the air inside, is pushing the rubber out. When the star explodes, there's nothing to keep it from collapsing under its own gravity. You get to a point where 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 huge chunk of iron that's not being held up by anything. And so it starts to collapse under its own gravity. 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. So you end up with the singularity, this point of infinite density, technically. What is the shape like?

Is it like an ice cream cone that has an infinite tail or what is it? I mean, you can visualize it that way if you think about it in terms of like a 2D analog. Like usually when we think of space time, like the pictures are always like a big rubber, 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, green school summer 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 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, right? This is the usual visualization for space time. But that doesn't have the right number of dimensions because space is three-dimensional

and then you can think of time as another dimension, but that's kind of separate thing. I am curious about time as a fourth dimension, too. We can talk about that. OK. But we're going to take a quick break for sponsors of the show, sponsors, why sponsors? You know what they do?

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Okay, I'm sorry, I have so many questions. But anyway, so if space is three-dimensional, then the way gravity works on it is that it kind of pulls space inward toward itself. So a massive thing pulls space inward towards 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 that 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 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 kinda breaks and it's better. But yeah, so it's basically a place where space is really super curved.

Okay. Really super bent inward. And so there's a point, so if you think again about the 2D kind of thing, the rubber sheet, you can still move past, like if you have your little hole that you've pulled down on your 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 there's this horizon, this distance 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 a flashlight into a black hole, like that light never comes out again.

It just keeps, it goes 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 horizon. That is the event horizon. Yeah, that's the event horizon. I mean, you should probably stay farther than the event horizon. Okay, that is the event horizon. Yeah, that's the event horizon I mean you should probably stay farther than the event horizon in general

Because other bad things can happen to you if you get close to the black hole if you listen to Oligies 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 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 a form of a disc. And so that'll radiate you to death if you get too close. And then if you get close,

if it's a small enough black hole, then when you get close, the title forces will kill you. So title force is where you have, like, it's where you have more, more grab, the gravity is pulling stronger on part of you than another part. Oh, no. So 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

Uh-huh. 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 Yeah, yeah, so, so you have to want out for spaghettification if you get too close to black hole Who the hell made that? 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. Of all of the things. Like turns you to spaghetti. I don't know.

Like that's just, what else are you going to call it? Like, I mean, it's title disruption, but I love it. I know. The most. Yeah. Spaghettification 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 really silly names in astronomy. Who gets to name this stuff? Whoever comes up with it, I mean, people who come up with a name it, but like sometimes the community names it, like the Big Bang, that was a joke. Like, 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 stuck. No. It was a throwaway. Yeah, it was like, it was mocking. Did that person get pissed at 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 1940s and it was kind of on accident. Now, the story is, he's so bent that it stuck, but apparently he denies that. So, drama. In terms of what, in terms of what your output is, you is, you're a professor, you give talks to travel 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 end game? So what do 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 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 in these

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 is a galaxy's form and then we can look for 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 working vault? Do you have like a mole skin that's just filled with

like gobbledy gook 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 most skin with the 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 most skin. 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 observation 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 write stuff 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 imagined physicists needed to be sequestered in a well-appointed lab or a classy den to just think clearly. But no, there's like a lot of chatting happening. And then once you figure out what equations you need to solve and what things you need to calculate,

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, and see if it all kind of clicks. Yeah, yeah. And you see if 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 in nobody's 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 going to write it up and be really happy about it.

And then you go toward writing it up and publishing it. Yeah. 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 so funny to me because they're so specific and wonderful. I mean mean I guess it depends on what you mean. I wrote a paper called Known Unnones of Dark Man or an Eilation over Cosmic Time. That sounds

like the best like Norwegian Metal album ever. It was like well yeah so that was all about what we know we don't know about this problem. I've calculated a bunch of stuff. I've had some papers about axions 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 it to be... I mean, you kind of want it to be punchy, right? Like, the whole no-no-no-no thing is I want 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 it. 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 arxiv.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 that it's ARXIV, is how it's spelled,

we call it the archive. The archive website displays like 100 new papers about astronomy. And there's just a list, and the titles, so there's the titles and the authors, and maybe like 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 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. That's so much work. It's so

much work. It's heck 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 particle 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 I if you're trying to read particle theory and phonomenology and Astronomy you can get like 150 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, 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 duh. There's a cutoff time of like 4 p.m. 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... Oh my God. And so there's this, you can, people have written papers about like the spike in submission times, or like everybody's trying to get like four, 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 ritual of when you submit your paper to the archive, you're trying like, you watch the clock and you try and hit the submit button, at exactly the right moment. That makes me so anxious. It's like when someone people comment first,

on a YouTube video. It should be randomized because it's also been shown that it does matter in terms of like citations. That's not right. It should be randomized because it's also been shown that it does matter in terms of citations. That's not right. It's not right. Oh my god. Yeah.

Oh wait, what was a question that I had right on top of that? 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 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, I'm like I'm still trying to remember what the difference is between a bug and not a bug, right? Like I don't know

I'll give you some clearance on that. Okay the problem is, is you study the universe. Yes. So, could your field be any broader? Like, 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. Oh my god. I think we'll find the questions. And that used to freak me out a lot and now I just feel 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 I gave the talk about gravitational waves in rally the other week and one of the questions was Tell me about the great red spot on Jupiter and I was like G-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o about the great red spot on Jupiter and I was like, it's a storm, it's been shrinking. There's a space craft looking at it, you should maybe talk to somebody who studies about that.

The great red spot, by the way, that's a 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 Pole. 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 LIGO project you may have heard about in 2016. The detection of gravitational waves by the LIGO instrument was probably the biggest discovery in physics in my lifetime. Yeah, that's a big deal. It's a super big deal. I win the announcement. So the first the first detection was last year sometime or well the detection was the end of 2015 and it was announced I guess during 2016. The announcement was in, I don't

remember what time zone it was or whatever, but it was such that it was going to be 2am 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 we watched videos, and we took selfies. It was really late, but we got to see this live. There were two people in the room who were part of the collaboration, so they already knew what was going to be done. The rest of us, we'd heard rumors, but we didn't know for sure what that was gonna be announced. And yeah, it was just a huge party. And it was a, we were really excited.

And like we just, everybody was like clapping and stuff when it happened. And I mean, it was, it was a huge deal. The way that it was announced was like a press conference from like an awesome 80s movie. Ladies and gentlemen, we have detected gravitational waves. We did it. I mean, how cute is that? So that was Dave Wrightsy. 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. Yeah. I got it. I thought 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 so first gravitational waves are our 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, an 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 that's not detectable. 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. And 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. 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. What? So let's say that you're standing there and a gravitational wave comes and 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. What? And like it oscillates back and forth. So as the waves are coming at you, each wave is giving you that stretch and squeeze, stretch and forth. So as the waves are coming at you each wave is giving you that like that stretch and squeeze stretch and squeeze And so it's actually distorting your shape. Oh my god. This is happening. This is like a big boy are yawning and it's it keep like For everything that creates gravitational waves is it's doing this doing all the time micro micro basis? Yeah, yeah, so waves, is this doing this tome all the time? Micro basis? Yeah, yeah. So, so the LIGO experiment is built to detect these things. 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, it's some shit that we built

like on Mars, because there's just this treeless ochre 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, they meet at the center and 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 phase 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 has changed. And then that's the signal, is the changing of the length of the arms, and the level on which that happens, so this is four kilometers, right? 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.

So it was like 1.3 billion light years away, so it was very far. But it was like the black holes were around 30 times as massive as the sun. Oh god. 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 you have to do lots of processing. But like you could see the signal is very strong. But yeah, thousands of the width of a proton. So your own height is changing much less than that, right? Because you're not 4 kilometers long. Sure. I'm getting a little bit not quite as tall and not quite as skinny and not quite as short

as fat as it's not noticeable in a photograph, say. Yes. Yeah, it's really, it's a really subtle effect. 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. Any time the black holes, black holes, or something collide, you get this kind of like, 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, ooh, and the 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 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 round the world, right? Yeah, it's called a chirp. A chirp, yes. Just a little, yeah, chirp, a chirp.

Okay, you ready for this? This is the sound of history. So what does that mean going forward for astrophysicists? Yeah. And 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, seen now. And the most recent one was two black holes, but the

one before that was a neutron, there was two neutron stars. And those were a big deal because those, when they collided, also created a gamma ray burst, a gamma ray burst, super energetic explosion. So we can't see gamma rays, but they pack a 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 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 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. 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 we had indirect evidence that 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 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 about 100 years before the first detection was made. So it took a long time to see these things. But so it confirmed that. And it's just this incredible laboratory for for relativity for physics. Because by detecting the gravitational waves and looking at the signal, we were able to determine that gravitational waves traveled the speed of light.

That 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. 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 bursts creates. A lot of stuff about that. And then because now we can watch black holes colliding in the distant universe, we can learn

about how black holes grow when 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 are a kid were you ever hoping that this that we would be able to detect gravitational waves? Um, so like I've been waiting since I was a little girl. Um, so like I've been waiting since I was a little girl. Um, so, so I didn't know a lot about gravitational waves when I was a little kid, but there was, there was a really beautiful moment, um, during one of the, the detection of the neutron star collisions when one of the scientists, um, 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 chirps sound Okay, here's a sound of the neutron stars boop in 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 which takes a while and it does it So, and there'd been simulations of this for years. I mean, the scientist who was talking about the discovery said that he'd been waiting to hear that sound from nature for 20 years. And he just did. And it was really touching. I mean, so for me, I knew about Lago because it was, it was partly headed by people at Caltech and I was an undergrad at Caltech. And so when I was an undergrad there, people were talking about a lot.

And there was a famous bet between like Kip Thorn and Stephen Hawking or something. Kip Thorn, by the way, is a theoretical physicist, the 2017 Nobel Laureate, about whether or not gravitational waves would be detected by the year 2000. I started Caltech in 99, so they were not detected by the year 2000, so that bet was lost. But it was a funny thing, because when I first got to Caltech, they were building LIGO, and it was this big deal, and everybody's like, we're going to detect gravitational waves, it's going to be amazing. And then, you know, building LIGO and it was this big deal and everybody was like, we're going to detect gravitational waves. It's going to be amazing. And then LIGO was being built and I was like, oh, it's any minute now.

And then I left Caltech and I went to grad school. And then after a while, I was like, I haven't heard anything about this for a while. And I realized that they'd kind of like, they'd been like, yeah, we're going to detect gravitational waves. And they kind of got quite for a while. And I found it later on asked about it and they were like, oh no, it's advanced LIGO. So there are some upgrades of the years from initial LIGO

to enhanced LIGO, to advanced LIGO. It's kind of like the tall, grande, and venty gravitational wave detectors. Just then maybe you need a little more to get the job done. Really gonna do the detection. The initial Lego was like, maybe it would get lucky, but advanced Lego will really see something. I'm like, really?

And 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 gonna happen. But then, you know, as soon as they turned advanced Lego on, like within like a week or something, they saw this thing so that's quite 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 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 much the photons hitting the mirrors would move them. Oh, my God. Oh, my God. Oh, my God. That's a big part of the noise in the signal. Like, that's called the photon shot noise.

So I have to deal with that. Yeah, stuff like that. I mean, it's incredible that they were able to do this. So can you get the chirp as a ringtone? I believe you can. You can? I believe so, yes. Would you get the neutron whoop?

Or would you get 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 in the actual data, it's like... That's kind of what it sounds like. But then when you speed it up, it goes, but it's very quick.

Whereas the neutron star one, it's like, oooh! I feel like... It's much cooler. 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 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 were some there was a free book pile. Oh yeah. 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 Chone and it's delightful. I found my copy. It's still moldy from a monsoon. It was good. It was very, it was very lay person's terms. Excellent. I clearly 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 Astro physics for dummies. What are we talking here? Is there a pamphlet?

So I wish I had a really good answer for this Like you don't You're wincing the thing so the thing is like I is, I don't read a lot of popular level stuff. There's a couple of reasons for that. Number one, she doesn't have much time to read non-papers because there's a billion papers. When she likes to read about spaceships, Okay. When something is written for the general public, astrophysicists 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 were a bartender and someone writes, she drank a whiskey, but you're

distracted wondering, a whiskey will do it like a bourbon? Is this a single malt scotch? Was it a rye? Tennessee whiskey? Is single malt scotch? Was it a rye? Tennessee whiskey? Is this on the rocks? Was it in a cocktail? There's so much detail in it. I mean, Sean Carroll's written several books

that are really good. So take a look at those. And there's a physicist, Katie Freeze, Catherine Freeze, who's a dark matter theorist like me. Oh. She's a dark matter cosmologist, and she She's a dark matter cosmologist and she's written a book called Cosmic Cocktail and it's all about about dark matter and also like some autobiographical stuff. It's really cool. What about what about movies? Do you have a favorite or at least favorite movie about space or cosmology?

You're like, can I not answer some of that? Yes, yes, yes. Okay, 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 skills, is incredibly long times and so having something happen within a movie time frame 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. some cosmology-ish stuff in it. So that was sunshine, which the science is wrong. Just putting that out there. It's about the sun has burned out or is burning out and they have to fix it. And none of that can happen. All of that's false, all of that's fake. But it's done really well in terms of like they have physicists who acts like a physicist and like they have people who talk like scientists and I kind of just enjoyed it.

So I thought that, and then there's a monster thing. So anyway, but I thought that was done really well. I really enjoyed gravity. There's also bad physics and 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, 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 were 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 proper relativistic equations.

It was very clever because what they did is they had these simulations that are very, very difficult and take a very long time on supercomputers and they gave them to the people who do movie graphics who have really powerful super supercomputers and they gave them to the the people who do movie graphics who have really powerful super super computers 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 the calculation done for the graphics in the movie. Because movies are better funded than... Yeah, that's a good move. Yeah, so it was a very good move. But you should know that the black hole in Interstellar, although there are some aspects that are done very faithfully,

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, Keating 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 rap of fire around of all of your questions. So I asked your questions. We raced 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 orinic express. It features a very bizarre mustache. I will give it that. So stay tuned. It's a first two-parter analogies 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 allergies stay up there in the science charts, so more folks know about it. So thank you so much. Katie is at Astro Katie on Twitter, where she has approximately $1 billion trillion followers, and she has academic nomad on Instagram.

So thank you to all you all of Gites for tweeting and grahamming and meaming at us, and to all the folks on Patreon who make the show possible. It is currently 4 a.m. on a Friday night and I'm recording this to send it off to Stephen Ray Morris. He's gonna help edit it and your funding is making this dream project possible and putting a lot of facts in a lot of human minds. You can also keep the show going by stopping at oligee's merch.com. I also want you to know that yes, it's super late at night.

And I'm recording this partly because the mass of porridge that occupies the space where a brain would be had to spend a little longer trying to understand and explain these concepts than I thought. And right now, as I record this, mill 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 allegies or alleyward.

I'm sure I'll have a new secret for you next week at the very end when we are back with Kani-Max Q&A. So until then, ask smart people dumb questions because I love it. And we're just tiny meat blobs on a dust spec. So let's just live. Can we live? Okay, bye bye! Crypto-Zoology, Lysology, and Zanology. Meteorology, Doology, Faculty of Technology, Nephology, Cereology, and Technology. you