Speaker 1: Hey, Katie, do you have science words that you especially like? Yeah,
Speaker 1: I really like apoptosis. It makes me think of popcorn.
Speaker 1: That does make me want to have a snack. Well,
Speaker 1: I like the word fundamental. It sounds so important, it's
Speaker 1: got fun in it, it does. So what science words
Speaker 1: don't you like? Um, coagulate, I was afraid you're gonna
Speaker 1: say moist coagulates pretty gross. Also, I'm not such a
Speaker 1: fan of the word had drawn. No, the problem is
Speaker 1: a lot of people end up with a little typo
Speaker 1: that swaps a couple of letters and you end up
Speaker 1: with something very not safe for work. Yeah, that gives
Speaker 1: the lard hay drown collider a whole different connotation. Hi,
Speaker 1: I'm Daniel, I'm a part of Old Physicist, and I
Speaker 1: definitely am colliding hay drowns at the LHC. And I
Speaker 1: am Katie Golden. I'm stepping in for Jorge this week,
Speaker 1: and I am the host of Creature Feature. I'm a
Speaker 1: science podcast interested in evolutionary biology, human psychology, and hate
Speaker 1: also physics and Welcome to the podcast. Daniel and Jorge
Speaker 1: explain the universe, in which we take you on a
Speaker 1: mental journey to understand everything about the universe, from the
Speaker 1: tiniest things between your toes to the things you see
Speaker 1: in the night sky to the vast weird, crazy bonker
Speaker 1: stuff going out in the depths of space. We take
Speaker 1: all of it, roll it up and try to make
Speaker 1: sure that you understand it. Like a cosmic burrito. How
Speaker 1: much hot sauce you want is up to you. And
Speaker 1: we love to talk about stuff that we see in
Speaker 1: the night sky, but we also love to talk about
Speaker 1: stuff you might not have even heard of. When you
Speaker 1: look up in the sky, you see stars, and if
Speaker 1: you have a nice telescope you can even see further
Speaker 1: in meb see those smudges that our galaxies. But there's
Speaker 1: a lot of other stuff out there in the universe
Speaker 1: that we are not familiar with, that most people don't
Speaker 1: even know exists. Okay, so if I'm looking at the
Speaker 1: night sky, I see a bunch of stars. Sometimes I
Speaker 1: see like, like you said, it looks like someone spilled
Speaker 1: a bunch of sugar up there, and it's a galaxy.
Speaker 1: But what can I possibly be missing? I mean other
Speaker 1: than yeah, I guess I can't see them in detail
Speaker 1: with a telescope, But but what what's up there? Like
Speaker 1: you mean giant alien eyeballs. Well, there's a lot of
Speaker 1: stuff out there. And basically, every time we turn on
Speaker 1: a new telescope or a new kind of device for
Speaker 1: we're listening to the Cosmos, we find something new. And
Speaker 1: every time we ap peer deeper and deeper into the sky,
Speaker 1: we see stuff that we didn't expect. On the podcast today,
Speaker 1: we'll be talking about a weird thing that's in the
Speaker 1: sky that astronomers have known about for hundreds of years,
Speaker 1: but most people aren't aware of. All Right, well, what's
Speaker 1: this big secret? What if astronomer has been keeping from us? Well,
Speaker 1: unfortunately it's got a really strange and kind of an
Speaker 1: ugly name. Oh, it's not coagulated. It stars don't coagulate.
Speaker 1: I guess if a galaxy cuts itself right, a bunch
Speaker 1: of like stars could rush in to fill in the
Speaker 1: gap planetary platelets. No, Today on the program, we'll be
Speaker 1: asking the question what are globular clusters? You? Doesn't sound
Speaker 1: like something you want to order on the menu, does it? No?
Speaker 1: It sounds like the worst kids cereal? Ever, like, be
Speaker 1: sure to get globios for your globular clusters. I know,
Speaker 1: I imagine some like scoop of some very viscous kind
Speaker 1: of stuff. It's like jello mixed with gravy or something.
Speaker 1: Oh man, I don't I have a texture thing when
Speaker 1: it comes to food, Like I don't like cottage cheese
Speaker 1: or other like things, little chunks suspended within goo. So
Speaker 1: I don't know about this globular clusters thing. This does
Speaker 1: not sound good. Well, fortunately it was not designed as
Speaker 1: a menu item. It's an astrophysical object. It's something out
Speaker 1: there in our universe that might teach us something about
Speaker 1: how the galaxy was formed, and how old the universe is,
Speaker 1: and weird new kinds of stars, and so it's an
Speaker 1: opportunity to learn something. Unfortunately, we don't actually have to
Speaker 1: taste it. That's good, that's good, all right. I'm still
Speaker 1: with you then, But if you try to give me
Speaker 1: a spoon on one of these globular clusters, I am check. Please.
Speaker 1: So we asked what people think globular clusters are, and
Speaker 1: this is what people have to say. I don't know
Speaker 1: what a globular clusters. I think it might be something
Speaker 1: found in out space, but I don't actually I'm not
Speaker 1: sure entirely, but I think it's just some type of
Speaker 1: grouping of stars, assuming it's a term from cosmology. A
Speaker 1: cluster is a collection of stars, and globular means that
Speaker 1: it's round like a globe, and you'll as in molecule
Speaker 1: or module, suggests that it's small, so it's a small
Speaker 1: round a bunch of stars. This one is like a
Speaker 1: gathering of stars spherical. It's not a galaxy. It can
Speaker 1: be within a galaxy, but it may look like a galaxy,
Speaker 1: like a spherical galaxy. I've heard the phrase globular or cluster.
Speaker 1: I'm not sure what it means. I thought that it
Speaker 1: had something to do with a group of stars, maybe
Speaker 1: that are clustered together in a spherical shape. This is
Speaker 1: a gigantic group of stars sit outside and I think
Speaker 1: maybe even all of it the galaxies. This has something
Speaker 1: to do with a group of stars, maybe that they
Speaker 1: all formed from the same nebula or um other event.
Speaker 1: Thanks to everybody who volunteered to speculate baselessly without getting
Speaker 1: to do any research or googling. If you'd like to
Speaker 1: participate for a future episode, please write to me two
Speaker 1: questions at Daniel and Jorge dot com. I think it's interesting,
Speaker 1: so most of the answers more along the same lines
Speaker 1: like this is probably a big cluster of stars or
Speaker 1: some kind of space junk, some kind of space junk.
Speaker 1: But then no clue in there that it's a cluster
Speaker 1: of stars, right, it could have been a cluster of anything,
Speaker 1: you know, jello or gravy or breakfast cereal or whatever.
Speaker 1: I think when people think about space, you think of
Speaker 1: it mostly stars. Right, you look out into space. What
Speaker 1: do you see? You see stars. All the other stuff
Speaker 1: that is out there is either hard to see or
Speaker 1: isn't really perceivable. Yeah, but you hear some people speculating
Speaker 1: like maybe it's a cluster of galaxies or a cluster
Speaker 1: of galaxy clusters or something like that, because there's this
Speaker 1: fascinating sort of hierarchy of structure out there in space. Right,
Speaker 1: It's not like they're just stars everywhere. Things are sort
Speaker 1: of grouped together into galaxies, and those galaxies are grouped
Speaker 1: together into clusters of galaxies, and so there's like this
Speaker 1: really fascinating sort of hierarchy of structure is getting bigger
Speaker 1: and bigger and bigger. And so I guess the question
Speaker 1: then is, you know, like what are globular clusters a
Speaker 1: cluster of Yes, what kind of pyramid scheme is a
Speaker 1: globular cluster. Who's the downstream and who's the upstream? Who's
Speaker 1: really making money off globular clusters? Right? Who's behind big
Speaker 1: globular taking globular clusters to the moon. So the answer
Speaker 1: is that globular clusters are clusters of stars. And to me,
Speaker 1: the fascinating thing is that there's something in between, sort
Speaker 1: of like our Solar system and the galaxy. Do you
Speaker 1: think about like our cosmic address. We're here on Earth,
Speaker 1: we're zooming around our star, and then we think that
Speaker 1: our star is just like one of many stars of
Speaker 1: hundreds of billions of stars in the galaxy. But it
Speaker 1: turns out that there's an intermediate step there. It's not
Speaker 1: like just Solar system and then galaxy. You could have
Speaker 1: organizations of solar systems. So when you zoom out, like
Speaker 1: when you see these videos of here you are on
Speaker 1: planet Earth. You're tiny and significant, flee like creature on
Speaker 1: this huge planet. Then you zoom out to Solar system
Speaker 1: and usually goes right from Solar system to galaxy. But no,
Speaker 1: there's an extra step. You're saying, there's an extra step. Yeah,
Speaker 1: some stars, some special stars grouped together into these big
Speaker 1: clusters of stars called globular clusters. Now, not every star
Speaker 1: is in one of these things. It's not like, you know,
Speaker 1: another layer in this hierarchy is sort of like a
Speaker 1: special clumping. Like most stars are just sort of like
Speaker 1: out there on their own, sort of like out in
Speaker 1: the middle of the countryside by themselves. But it turns
Speaker 1: out that there are these like urban areas where stars
Speaker 1: clump together really densely and make these things called globular clusters.
Speaker 1: And they're like a fascinating relic of the ancient formation
Speaker 1: of the galaxy and can tell us a lot about
Speaker 1: how things work out there. So it's like you've got
Speaker 1: a bowl of granola, and yet you have your little
Speaker 1: oatmeal pieces in there, but then you have the big
Speaker 1: clusters of oatmeal too. Those are the best ones. Those
Speaker 1: are the best ones. Those are nice. Yeah. I always
Speaker 1: fish those out first, and then I'm left with just
Speaker 1: sort of a bowl of sugary oatmeal and that's not great.
Speaker 1: But so that whole bowl is like the galaxy, but
Speaker 1: within that bowl you have the globular clusters of the
Speaker 1: nice crunch granola's. Yeah, exactly. The stars are not evenly
Speaker 1: distributed through the galaxy. I mean, the overall pattern is
Speaker 1: that there's more stars in the center of the galaxy
Speaker 1: with a gravity stronger, and then it's sort of peters
Speaker 1: out along the galactic disc. But inside there it's not smooth.
Speaker 1: There are these clumps where you get these big collections
Speaker 1: of stars. And we're not talking like, you know, five
Speaker 1: ten stars. We're talking like a few hundreds of thousands
Speaker 1: of stars. It's a big deal. Sounds like when they're
Speaker 1: making the galaxy that just didn't stir enough. That's what
Speaker 1: I learned about. Like when I'm trying to make polina,
Speaker 1: you know, it gets clumpy. You just didn't stir enough.
Speaker 1: Katie's globular polenda. That's not the foundation for your next
Speaker 1: food truck, right, And so these things have like a
Speaker 1: few hundred thousand stars in them, but they're not actually
Speaker 1: that big, right there only like ten to sometimes like
Speaker 1: three hundred light years wide. Okay, you say that's not
Speaker 1: that big. However, how long would it take me to
Speaker 1: drive from one end to the other of three hundred
Speaker 1: light years? Yeah, it would take you a while. I mean,
Speaker 1: even in your light speed polenta powered vehicle, it would
Speaker 1: take you three hundred years to go across three hundred
Speaker 1: light years obviously, and in a much slower, more reasonable
Speaker 1: ship it would take much much longer. But the reason
Speaker 1: I say that it's not that big is that there
Speaker 1: are so many stars in there. So would you end
Speaker 1: up with is stars in a very unusually dense collection
Speaker 1: like in our part of the galaxy in our neighborhood,
Speaker 1: there aren't that many stars, like the nearest stars more
Speaker 1: than four light years away, right, I mean, it seems
Speaker 1: like there would be conflict with stars being that close together, right,
Speaker 1: because I know every body in the universe has some
Speaker 1: kind of gravitational poll and stars are so big they
Speaker 1: seem like they would be acting on each other there,
Speaker 1: So it's it's odd that you would have them so
Speaker 1: close together. Yeah, And that's exactly what makes them fascinating
Speaker 1: because in these clusters we get to see stars doing
Speaker 1: something they don't normally do, which is like dance around
Speaker 1: each other and tug on each other and form new,
Speaker 1: weird kinds of stars. And we're gonna dig into all
Speaker 1: that crazy stuff that's happening inside the globular clusters in
Speaker 1: a minute. But here's some numbers for you, Like the
Speaker 1: density of stars in our neighborhood. Like around where we
Speaker 1: live in the galaxy is like one star per three
Speaker 1: hundred cubic light years, so that's pretty big area just
Speaker 1: to get one star. But inside one of these globular
Speaker 1: clusters there's like two stars per cubic light year, so
Speaker 1: it's like six hundred times denser than it is in
Speaker 1: our neighborhood. It's like going from the middle of nowhere
Speaker 1: to Manhattan. Really packed in there, like star deans. Yeah,
Speaker 1: they really are. Imagine what it would be like to
Speaker 1: live around a star in a globular cluster. You would
Speaker 1: have so many other like bright stars in the sky
Speaker 1: at night. The night itself might be a lot brighter
Speaker 1: than it is here. Yeah, it seems I would be
Speaker 1: as bright as daylight. You just have too many suns
Speaker 1: going on. Yeah, if you're near the center one of
Speaker 1: these things, I mean, the globular cluster itself is like
Speaker 1: twenty five thousand times brighter than the sun. These things
Speaker 1: are really bright. Some of them are up to like
Speaker 1: fifty times brighter than even that. You'd be in the
Speaker 1: middle of like a lot of light bulbs all the time.
Speaker 1: Maybe a pretty crazy experience. Well, I need to get
Speaker 1: some more high tech sunglasses. It seems like to be
Speaker 1: able to live here some of that those polarized shades.
Speaker 1: But before I do that, why don't we take a
Speaker 1: quick break and I will return with all new sunglasses.
Speaker 1: All right, I've got my super polarized super extra anti
Speaker 1: glare globular cluster sunglasses on. I can't see a thing indoors,
Speaker 1: but I think it'll help me see within the globular clusters. So,
Speaker 1: so what's going on around me? Yes, So these globular clusters.
Speaker 1: You have this big collection of stars all packed into
Speaker 1: one spot. And one of the amazing things is that
Speaker 1: there aren't actually that many of these, Like the galaxy
Speaker 1: has hundreds of billions of stars, but they're only about
Speaker 1: a hundred and fifty, maybe up to two hundred of
Speaker 1: these globular clusters. Well why are they so rare? We
Speaker 1: don't really understand, and we can talk in a minute
Speaker 1: about how they form, but one clue is that they're
Speaker 1: also not always contained within the galactic disk. Like when
Speaker 1: you look at the galaxy sort of from outside, which
Speaker 1: we can't do what we can look at other galaxies.
Speaker 1: Of course, you see that it's mostly a flat swirl,
Speaker 1: and that's because of how the galaxy formed. Right, the
Speaker 1: galaxy form from a huge collection of gas and dust
Speaker 1: which collapsed into stars and then gravity took over and
Speaker 1: try to pull all those stars together, and that's why
Speaker 1: you have a galaxy. But it's my it's harder for
Speaker 1: gravity to pull along the galactic plane because that's how
Speaker 1: the galaxy is spinning. That's spinning keeps things from falling
Speaker 1: in only along that plane. Perpendicular to that plane, you
Speaker 1: can squish it flat like a pancake. Is it sort
Speaker 1: of like when you have a bicycle wheel, You have
Speaker 1: some torque there, so you have that kind of like
Speaker 1: inward energy of the galaxy spinning, So it's easier for
Speaker 1: it to be flat and spinning inward than it is
Speaker 1: to spin another direction. Yeah, exactly, if you spin a
Speaker 1: bicycle wheel, then it's harder for things to sort of
Speaker 1: fall in towards the center. Or if you think, for example,
Speaker 1: about like a merry go round with ping pong balls
Speaker 1: on it, right you spin that thing, the ping pong
Speaker 1: balls are all going to fly out, but they're gonna
Speaker 1: fly out along that plane. So that's what we call
Speaker 1: rotation supported. The rotation of the galaxy is keeping things
Speaker 1: from falling inwards, but again only along that plane. There's
Speaker 1: nothing that prevents the collapse perpendicular to that plane, which
Speaker 1: is what makes it flat like a disk. Well, next
Speaker 1: time I go on a Merry go around, I'm bringing
Speaker 1: a bunch of ping pong balls with me. This is
Speaker 1: probably why I'm banned for most Merry go round. Maybe
Speaker 1: also because you try to eat polenta and you end
Speaker 1: up throwing up globular chunks of polenta. Oh man, When
Speaker 1: I was a kid, I was a throw upper kid,
Speaker 1: and I had some moments. I had my moments, especially
Speaker 1: on the teacups. All right, well, we don't want to
Speaker 1: revisit that with too much to jail. But the interesting
Speaker 1: thing about these globular clusters is that they don't tend
Speaker 1: to be along this galactic disk. Like if you looked
Speaker 1: at a diagram of where they are, there's some of
Speaker 1: them that are in the disc, but they're also sort
Speaker 1: of just spherically distributed around the galaxy. It's almost like
Speaker 1: they come from a time when the galaxy was a
Speaker 1: big puffy sphere before collapsed. Right, And I'm looking at
Speaker 1: this image and what it looks like to me is
Speaker 1: like a side view of like a fried egg, and
Speaker 1: then above it, like scattered around it are little little
Speaker 1: yellow dots like you just spilled a bunch of salts around. Man,
Speaker 1: I keep coming back to food on this globular cluster episode,
Speaker 1: don't I. We've gotta stop recording these at lunch. Whoever
Speaker 1: thought globular clusters would make you hungry? Like, I gotta
Speaker 1: bring a positive spin to it. So they're falling outside
Speaker 1: of that disk. You're saying that maybe these had formed
Speaker 1: back when the galaxy was sort of this big puppy cloud,
Speaker 1: and even as it flattened down to the disk, they
Speaker 1: didn't come with the rest of the game. Yeah, precisely.
Speaker 1: And there's a bigger topic here of the galaxies halo.
Speaker 1: Remember that galaxies are not mostly stars. Most of what's
Speaker 1: in the galaxies actually dark matter. And if you look
Speaker 1: at where the dark matter is in a galaxy, it
Speaker 1: doesn't collapse the same way that normal matter does. It
Speaker 1: tends to spin. And so this is big spherical halo
Speaker 1: of dark matter around the galaxy. And that's the original
Speaker 1: thing that's sort of like clustered together the gas of
Speaker 1: dust that made our galaxy. And so these globular clusters
Speaker 1: they're sort of in this larger galactic halo, but they
Speaker 1: haven't collapsed down into this disk, and we don't know
Speaker 1: exactly why. It could be that they didn't form with
Speaker 1: the original galaxy but are like their own little mini
Speaker 1: galaxies that were then captured later and that's why they're
Speaker 1: orbiting around. Or it could be that they formed with
Speaker 1: the rest of the galaxy but then didn't collapse as
Speaker 1: well as the gas and dust because they don't collide
Speaker 1: with each other as much as the gas clouds do,
Speaker 1: so they avoided like losing all that angular momentum and
Speaker 1: they can keep spinning around out there in crazy orbits.
Speaker 1: Or maybe they just prefer to hang out out in
Speaker 1: the dark matter halo. Dark Matter Halo is a really
Speaker 1: good metal band name, I've got to say. Yeah, So
Speaker 1: that that's interesting. We can't see dark matter, but it
Speaker 1: is there, and so it's like this halo around the
Speaker 1: galactic disc. And suspended in that halo are these little
Speaker 1: dots and those are each a globular cluster, yeah, exactly,
Speaker 1: and some of them happen to fall within the galactic disc,
Speaker 1: but most of them do not. You know. The closest
Speaker 1: one to us is about sixteen thousand light years away.
Speaker 1: It's called the Omega cluster. But there's a bunch of
Speaker 1: these things, and what's really interesting is how they form.
Speaker 1: And as you said earlier, they might tell us something
Speaker 1: about the age of the Milky Way, because we think
Speaker 1: that they formed very very early on as the galaxy
Speaker 1: was forming. You know, the way these things happened is
Speaker 1: that you get, you know, a big clump of gas
Speaker 1: and dust, and it may have been that you just
Speaker 1: got sort of like an over dense pocket of gas
Speaker 1: and dust something which was like, you know, got more
Speaker 1: of a serbing of globs than the rest of the
Speaker 1: stuff around it, and it collapsed all at once and
Speaker 1: made a big bunch of stars. And so these globular clusters,
Speaker 1: when we look at them, we see a bunch of
Speaker 1: stars and no gas and dust in between, which means
Speaker 1: like they're not forming any new stars. So there's sort
Speaker 1: of like a little time capsule from very very early
Speaker 1: formation of the galaxy. So when you say it happens
Speaker 1: at the same time, what are we talking about, Like
Speaker 1: it all happens within sort of one of our human
Speaker 1: years or is it literally like within a few moments?
Speaker 1: Oh wow, now we're talking like in within millions of years. Okay,
Speaker 1: star times. We humans are sort of like dogs. We
Speaker 1: live in dog years and they live in star years. Yeah,
Speaker 1: they live in star years. We think that these globular
Speaker 1: clusters are about eleven to thirteen billion years old. I remember,
Speaker 1: the whole universe is only just under fourteen billion years old,
Speaker 1: which makes these things some of the oldest things in
Speaker 1: the galaxy, which is how we can sort of use
Speaker 1: them to help understand the age of the galaxy. And
Speaker 1: also when we see them in other galaxies like Andromeda,
Speaker 1: we can use them to help understand the age of Andromeda.
Speaker 1: And one way we can do that is because we
Speaker 1: think that all the stars in there were formed at
Speaker 1: the same time, which means they all sort of like
Speaker 1: start their own clock at the same time. And you
Speaker 1: remember that the life cycle of a star is that
Speaker 1: it burns for a while and then ones is done
Speaker 1: with all of its fuel. It either goes nova or
Speaker 1: collapses or something. But the lifespan there depends on the
Speaker 1: original size of the star. The more mass it has,
Speaker 1: the faster it burns. The smaller it is, the longer
Speaker 1: it burns. So we can tell something about the age
Speaker 1: of these things just by looking at like the distribution
Speaker 1: of stars, which ones have burned out already, which ones
Speaker 1: have not. But the fact that they've all formed at
Speaker 1: the same time makes it very easy to sort of
Speaker 1: like reverse that back and understand how this thing started.
Speaker 1: It's nice from a scientific perspective because you control for
Speaker 1: the factor of age. You've got like these little test
Speaker 1: tubes out there that you can look at as physicists. Yeah, exactly.
Speaker 1: And they're also an interesting collection of stars because they're
Speaker 1: not stars like our sun. Our universe has gone through
Speaker 1: a few cycles of making stars. You know, the very
Speaker 1: early universe, you had hydrogen helium and that fell together
Speaker 1: to make the original first generation of ours, which weirdly
Speaker 1: astronomers called population three stars. And those were really big
Speaker 1: and didn't burn for very long, but they made some
Speaker 1: like helium and some heavier stuff and things that astronomers
Speaker 1: called metals. And then when they blew up and they
Speaker 1: spread their stuff through the galaxy, there was a second
Speaker 1: generation of stars which formed, and those are called population
Speaker 1: two stars. Some of those burned up and collapsed and
Speaker 1: spread their stuff through the galaxy to make population three stars,
Speaker 1: which is like our sun is a population three stars.
Speaker 1: But these stars in the globular clusters are only population
Speaker 1: two stars. There weren't any of the population one stars,
Speaker 1: the ones like our sun when these things formed. So
Speaker 1: you may have explained this. It counts down. It goes
Speaker 1: pop three pop to pop one is the newest or yeah, exactly,
Speaker 1: which I guess makes the next generation of stars are
Speaker 1: gonna be what pop zero and then pop negative one?
Speaker 1: Like nobody really thought this through pop zoomers. And the
Speaker 1: other fun thing about these is that that very low metallicity,
Speaker 1: Like there's basically just helium and hydrogen because that's what
Speaker 1: was around after the first generation of stars, the population
Speaker 1: three stars. You know, astronomers have this weird naming system
Speaker 1: for basically everything. Well one thing that's especially weird is
Speaker 1: what they call them metal. Like everything that's not hydrogen
Speaker 1: or helium is a metal to them because it's like
Speaker 1: a big heavy element. See. I mean, like, you know,
Speaker 1: there's a lot of controversy in the metal community of
Speaker 1: what can be considered metal. There's prog metal, and some
Speaker 1: people say, no, it's too much of a ballad to
Speaker 1: be metal, But you know, I think it's nice to
Speaker 1: be inclusive, and so these globular clusters that have basically
Speaker 1: only very low metal stars. And these stars are also
Speaker 1: not that big, which is why they've been burning for
Speaker 1: so long, and they might continue to burn for billions
Speaker 1: and billions of years more. The smaller kinds of stars,
Speaker 1: like red dwarves, they might even last for trillions of years.
Speaker 1: So these are very I guess gassy stars would be
Speaker 1: fair to say these sorry gassy stars. But the interesting
Speaker 1: thing is that they've sort of cleared out all the
Speaker 1: ask the dust inside of them. They're not making any
Speaker 1: new stars. Other parts of our galaxy still have these
Speaker 1: big blobs of gas and dust, so there's still new
Speaker 1: stars being made all the time, Like our son was made,
Speaker 1: you know, fairly recently on these time scales, only five
Speaker 1: billion years ago. But the globular clusters, they're sort of
Speaker 1: like you know, old boys clubs. They made all their stars,
Speaker 1: they used up all their gas and dust, and then
Speaker 1: they're done. They're just like, we're gonna hang out. We're
Speaker 1: happy with a number of stars. We have no new members. Typical. Typical.
Speaker 1: There are some places in the universe where globular clusters
Speaker 1: are still forming, like in the large Magellanic Cloud there's
Speaker 1: a big positive gas and people think that it's now
Speaker 1: forming into a new globular cluster. And by now we mean,
Speaker 1: you know, within the last twenty million years on star time,
Speaker 1: star time, not not a little human dog time. But
Speaker 1: there's still a lot of really interesting mysteries about these things.
Speaker 1: Most of them have sort of like a single population
Speaker 1: of stars that we think all formed at the same time,
Speaker 1: and you can tell based on like the star ages
Speaker 1: and sort of how they're like popping off and dying.
Speaker 1: But some of them have like two or three different populations.
Speaker 1: It looks like there was a clump all made it once,
Speaker 1: and then another clump all made at the same time
Speaker 1: that was different from the first clump. So there's a
Speaker 1: lot of interesting mysteries there. So is it more rare
Speaker 1: for globular clusters to form in our current universe than
Speaker 1: you think that it was like near the beginning of
Speaker 1: the universe. Yeah, absolutely, because a lot of the gas
Speaker 1: has already turned into stars or into globular clusters, and
Speaker 1: so it's very rare for globular clusters to still be made.
Speaker 1: Most of them were made in the early universe and
Speaker 1: they're just sort of like hanging around. They're like, you know,
Speaker 1: the old folks still smoking in the back of a bar,
Speaker 1: you know, and they're just not really making them like
Speaker 1: they used to anymore. There's just not enough gas to
Speaker 1: go around, which I can't believe I'm saying. And so
Speaker 1: we don't really understand like how these globular clusters have
Speaker 1: multiple different populations, Like people think maybe different globular clusters
Speaker 1: might have merged, like you had two of them formed
Speaker 1: at different times, and they sort of came to get
Speaker 1: there to make one that had two different populations in it.
Speaker 1: But it's you know, it's an area of active research.
Speaker 1: It's not something we really understand. So could I live
Speaker 1: in a globular clusters? What's going on in there? Is it?
Speaker 1: Is there anywhere for me to be? Are you looking
Speaker 1: to move, Katie? You are happy with your current apartment.
Speaker 1: I've got my cool shades that I currently can't say
Speaker 1: anything through, So I've gotta gotta find a place as
Speaker 1: bright as I am. It's a really fun question because
Speaker 1: it's fun to imagine what would like to be on
Speaker 1: a planet inside a globular cluster, And so people are wondering,
Speaker 1: like are there planets around these stars? Do these stars
Speaker 1: also have like planetary disks which collapse and give you
Speaker 1: rocky stuff that you could live on. Could there be
Speaker 1: alien life that evolved inside a globular cluster? We think
Speaker 1: actually it's pretty unlikely for these things to have planets
Speaker 1: around them, which is a bit disappointing when it comes
Speaker 1: to like writing science fiction novel about it. But there's
Speaker 1: really two reasons. One is that most of the material
Speaker 1: just sort of went to making stars, Like there's mostly
Speaker 1: gas there, so it's hard to form planets. Planets you
Speaker 1: tend to want to have like a rocky core with
Speaker 1: something heavy in it, But these things formed in the
Speaker 1: early universe when there was basically just hydrogen and helium
Speaker 1: and very small amounts of heavier stuff, so you didn't
Speaker 1: have sort of the raw ingredients to make planets. And
Speaker 1: the second is that it's pretty hard for a planet
Speaker 1: to stay orbiting a star if there are so many
Speaker 1: other stars nearby constantly tugging on it. Right, it seems
Speaker 1: like even if you could have like a gas planet,
Speaker 1: it would just get ripped apart by these quarreling stars. Yeah, exactly,
Speaker 1: and it would just get tugged out of orbit. You know,
Speaker 1: we think of our planet is mostly just orbiting the Sun,
Speaker 1: but there are gravitational forces from other nearby stars or
Speaker 1: things that pass nearby, and when the Sun comes nearby
Speaker 1: other stars, those things get stronger. So in a globular cluster,
Speaker 1: remember it's much much denser, there are many more stars,
Speaker 1: your byes of these tugs are a lot stronger. So
Speaker 1: even if you did form a planet and it did
Speaker 1: survive being pulled apart, as you said, you woul probably
Speaker 1: just get like passed around from star to star. Wouldn't
Speaker 1: have like a stable orbit like a volleyball exactly like
Speaker 1: a hot potato planet. That doesn't sound ideal for me
Speaker 1: as a little person living on this volleyball planet. So
Speaker 1: I'm gonna have to rethink my travel plans. So we'll
Speaker 1: take a break while I look into real estate in
Speaker 1: a different part of the universe. Alright, so we are back.
Speaker 1: I am looking at man Zillo just does not really
Speaker 1: go into like beetle juice area. There aren't very many
Speaker 1: sales to track there, so who knows how much of
Speaker 1: those houses cost. So we're talking about globular clusters. We
Speaker 1: have found out that I cannot live there inside a
Speaker 1: globular cluster, dream shattered but maybe there's something else we
Speaker 1: can get out of these globular clusters. Yeah, we think
Speaker 1: that there aren't planets around these things. And people actually
Speaker 1: went and looked and they studied a cluster and one
Speaker 1: of them had exactly zero planets in them. And then
Speaker 1: they looked at another cluster and they actually did find
Speaker 1: one planets, this huge Jupiter sized planet. But it's orbiting
Speaker 1: a pulsar in a binary star system. It's like a
Speaker 1: really rare and unusual kind of situation. And a pulsar
Speaker 1: is not what you want for like your home sun.
Speaker 1: So what is a pulsar? A pulsar is a star
Speaker 1: that's already collapsed, so it's burned it through its life
Speaker 1: and it doesn't have the energy to prevent gravitational collapse,
Speaker 1: and so it falls down into a neutron star and
Speaker 1: then it starts spinning crazily and emitting crazy radiation into
Speaker 1: the universe, which then sweeps across the sky and pulses,
Speaker 1: which why we call it a pulsar. We have a
Speaker 1: whole fun podcast episode about pulsars people can dig into.
Speaker 1: But pulsars don't emit light the same way like our
Speaker 1: son does because there's no fusion going on inside, so
Speaker 1: it would be a pretty chilly place to live. Well,
Speaker 1: I'll pack a sweater, pack all the sweaters. But there
Speaker 1: are some really interesting things you can do with globular clusters,
Speaker 1: like experiments, you can do questions, you can ask things,
Speaker 1: you can learn about the universe. To me, what's really
Speaker 1: interesting is that you get all these stars together, like
Speaker 1: really tightly packed, and so you get to see like
Speaker 1: what happens when stars get really dense, when they're like
Speaker 1: all tugging on each other gravitationally. Because you know, normally
Speaker 1: stars are pretty far separated, they don't really pull on
Speaker 1: each other that much. So it's like getting to study
Speaker 1: what happens when they get all crammed together. It's a
Speaker 1: starsh pit exactly. You get really interesting dynamics. Like some
Speaker 1: of these things have had what they call core collapse,
Speaker 1: where the center of the globe the cluster has a
Speaker 1: bunch of really really big stars and all the smaller
Speaker 1: stars are on the outside. And so they're trying to
Speaker 1: understand like are these because of gravitational interactions where like
Speaker 1: two stars come near each other and then sort of
Speaker 1: like throw each other in different directions and the bigger
Speaker 1: star always gets sort of thrown a little bit more
Speaker 1: towards the center, so that after billions of years, you
Speaker 1: end up with the smaller ones like in a little
Speaker 1: halo around the bigger ones at the center. It's like
Speaker 1: you have a bunch of dance partners, and you've got
Speaker 1: a bunch of little guys and some some big guys,
Speaker 1: and they're doing the dance from you know, the Titanic,
Speaker 1: where you hold hands and you spin around in a
Speaker 1: circle and then you let the other person go and
Speaker 1: they go flying. But it's a bunch of stars, and
Speaker 1: so maybe the little ones, like when they go flying,
Speaker 1: they fly out further, keep getting slingshotted out to the outside,
Speaker 1: whereas the bigger ones don't get tossed or heated. As
Speaker 1: the kids say as far, Yeah, that's exactly what happens.
Speaker 1: That makes the core of these things even crazier, because
Speaker 1: not only is it a place where there are a
Speaker 1: lot of stars, but now you have even bigger stars
Speaker 1: all clustered towards the center. So the heart of these
Speaker 1: globular clusters must be a really crazy place to live
Speaker 1: or even to visit. It seems slightly deadly. Potentially, you
Speaker 1: can also see really interesting new kinds of stars. There's
Speaker 1: a kind of star that seems to only exist inside
Speaker 1: a globular cluster. Yeah, and these actually I gotta give
Speaker 1: astronomers kudos because they have a cool name. These stars
Speaker 1: are called blue stragglers. Oh man, this sounds like I
Speaker 1: can just hear sort of like a guitar toWin going
Speaker 1: on and a country songs starting about the blue stragglers. Yeah,
Speaker 1: they lost their dog and their truck. But the interesting
Speaker 1: thing about these stars is that usually what happens to
Speaker 1: a star is a d percent determined by how much
Speaker 1: gas it started with and then how old it is.
Speaker 1: So you start with a bunch of gas and it
Speaker 1: burns for a long time, and you know, it's color
Speaker 1: depends on its temperature, which depends on the gravitation pressure,
Speaker 1: which depends again on just how much stuff it is.
Speaker 1: So you get enough stuff, you're gonna have a red giant.
Speaker 1: You get a little more, you can have a blue giant,
Speaker 1: for example. And so it's a very like well known,
Speaker 1: well understood sequence and stars should only appear like somewhere
Speaker 1: on this curve that tells you the mass and the
Speaker 1: age of the star. But inside these globular clusters is
Speaker 1: a weird kind of star called a blue straggler, and
Speaker 1: they're much bluer than you expect for a star of
Speaker 1: that size and that age. Poor things they got the
Speaker 1: blues that country music at all. It's the blues really,
Speaker 1: all right, So why are they so down? Are you
Speaker 1: talking about the color? Yeah, well, we don't exactly know.
Speaker 1: It's a fascinating area of study, something people are trying
Speaker 1: to understand. And that's what's really interesting about these globular clusters.
Speaker 1: It's like a new experiment. You know. Astrophysicists, they don't
Speaker 1: get to do experiments like particle physicists, where we like
Speaker 1: smash stuff together to see what happens. They don't just
Speaker 1: say I'm going to smash two stars together and see
Speaker 1: what happens. We don't have a star canon yet, we
Speaker 1: can't do it, yeah, exactly. We asked for funding for
Speaker 1: the Star game seventy two trillion dollars, but we haven't
Speaker 1: heard back yet. But what they can do is just
Speaker 1: sort of look out into the universe and see if
Speaker 1: these experiments are already happening. Because the universe is chalk
Speaker 1: filled with weird stuff, and if you look long enough,
Speaker 1: you'll see something that might answer your science question. And
Speaker 1: so we think that might be what's happening inside globular clusters,
Speaker 1: that essentially star collisions happened. That the reason these stars
Speaker 1: are like two or three times bigger than you expect
Speaker 1: for a blue star is that they sort of like
Speaker 1: got captured and fell together and formed an extra big star.
Speaker 1: So they just kind of like it's a collision and
Speaker 1: instead of all spreading out, it all kind of just
Speaker 1: starts to I hate to say it, but congealed together,
Speaker 1: coagulated exactly. And you know, that tells us something about
Speaker 1: star formation, because most stars we see formed outside globular clusters,
Speaker 1: and that tells us about the distribution. You know, you
Speaker 1: get a certain amount of helium and hydrogen, you get
Speaker 1: this kind of star of that kind of star. This
Speaker 1: tells us that under special circumstances, if you make a
Speaker 1: bunch of big stars near each other, they can combine
Speaker 1: together to make a super kind of star blue straggler
Speaker 1: that doesn't appear anywhere else in the galaxy or the universe.
Speaker 1: It's like a special star laboratory. And what's the straggler
Speaker 1: part of the name referring to if you look at
Speaker 1: the curve for where stars are, it's like color versus mass.
Speaker 1: Then there's this population of blue stragglers that are sort
Speaker 1: of off the curve. They're like to the left, and
Speaker 1: so they're sort of like not hanging out with the
Speaker 1: rest of them that are like falling behind. You know,
Speaker 1: you don't want to judge these stars and make them
Speaker 1: feel bad. They're just sort of different. They're differently starred. Yeah,
Speaker 1: they're differently started exactly. Globular clusters also give us a
Speaker 1: laboratory for trying to understand another mystery of the universe,
Speaker 1: and that has to do with black holes. Black holes
Speaker 1: form in our universe, but sort of only in two
Speaker 1: different groups. Like we either get black holes that form
Speaker 1: when stars collapse, and then they're about the mass of
Speaker 1: a star. And so we see black holes from stellar
Speaker 1: collapse and they're out there and they have masses of
Speaker 1: like ten to a hundred times the mass of our Sun,
Speaker 1: about what you would expect from the collapse of massive stars.
Speaker 1: Then there's another whole group of black holes that are
Speaker 1: like millions of solar masses, and these are the ones
Speaker 1: at the centers of galaxies. So you got like stellar
Speaker 1: black holes hanging out in the neighborhood, and then like
Speaker 1: the really big Papa black holes in the centers of galaxies.
Speaker 1: And one question in astrophysics for a long time is
Speaker 1: like where are the intermediate ones? Like why are there
Speaker 1: no black holes that are sort of like between a
Speaker 1: hundred and ten thousand solar masses right the Goldilocks black holes? Yeah,
Speaker 1: you know, why don't black holes emerge to form the
Speaker 1: bigger ones. It's an interesting question about like where they're
Speaker 1: made and how often it happens, and so this is
Speaker 1: something people have been trying to understand. And one possibilities
Speaker 1: that you might be able to make intermediate mass black
Speaker 1: holes in globular clusters because here you have like an
Speaker 1: unusual density of stars and if a bunch of them
Speaker 1: go black hole and then formed together, you might be
Speaker 1: able to make one of these things. So how are
Speaker 1: we going to do this? What do we need to
Speaker 1: make a black hole out of one of these globular clusters. Well,
Speaker 1: we don't have to do much. We just sort of
Speaker 1: sit back like astronomers and look out in the universe
Speaker 1: that's putting on a show for us. And the idea
Speaker 1: is sort of wait for one of these things to
Speaker 1: turn into a black hole. And then if there are
Speaker 1: a bunch of other black holes nearby, they could sort
Speaker 1: of swirl into each other. And remember what happens when
Speaker 1: you toss a black hole into a black hole is
Speaker 1: you just get a bigger black hole. Right, black holes
Speaker 1: don't like tear each other apart. Anything you tossed into
Speaker 1: a black hole just makes a black hole bigger. This
Speaker 1: is one of the favorite things people write in about,
Speaker 1: like what if I threw in, you know, antimatter into
Speaker 1: a black hole? Or what if I shot a laser
Speaker 1: into a black hole? Right? You can't destroy a black
Speaker 1: hole by adding more energy to it. A black hole
Speaker 1: is just a big blob of dense energy. So the
Speaker 1: more you add to it, the more black holely it gets.
Speaker 1: This is called the Kirby principle. Is at a cartooning joke.
Speaker 1: It's a it's a Nintendo character Kirby. He just sucks
Speaker 1: stuff up and he gets bigger and bigger. Awesome. Well,
Speaker 1: that's exactly what happens. And so black holes can eat
Speaker 1: other black holes and then become super black holes. Or
Speaker 1: if you start out with a bunch of smaller ones,
Speaker 1: you might get an intermediate mass black hole, and that'd
Speaker 1: be really interesting because maybe intermediate glass black holes do
Speaker 1: something different from the really big ones. Are the really
Speaker 1: little ones, you know, the really big ones are for example,
Speaker 1: sometimes their quasars they make crazy radiation because of all
Speaker 1: the gas and dust swirling around them. So this would
Speaker 1: be like a cool opportunity to just see something new
Speaker 1: we've never seen before. And so people are looking inside
Speaker 1: these globular clusters trying to see if there are these
Speaker 1: intermediate mass black holes inside of them. So when you're
Speaker 1: looking in a globular clusters, there a trick to being
Speaker 1: able to find a black hole inside one of these. Yeah,
Speaker 1: that's great question because you can't obviously see them directly.
Speaker 1: The way you can see a black hole is either
Speaker 1: gravitational lensing of the stuff behind it. So for example,
Speaker 1: of a star passes behind the black hole, than most
Speaker 1: of the star would disappear or some of the light
Speaker 1: from the star would bend around the black hole and
Speaker 1: you could see that sort of distortion. And actually a
Speaker 1: globular cluster is a great place to do that because
Speaker 1: you have a lot of stars moving all around, so
Speaker 1: it's easier to see this gravitational lensing effect I see.
Speaker 1: So the more activity you have, like, the easier it
Speaker 1: is to see the disruption of that activity as done
Speaker 1: by the black hole. Yeah, because you can see the
Speaker 1: black hole directly, you can only see its influence on
Speaker 1: stuff around it. So you can either see it bending
Speaker 1: the light that comes from behind it, or you could
Speaker 1: just see its gravitational effects on the nearby stars. Like
Speaker 1: the black hole that's at the center of our galaxy.
Speaker 1: We know it's there because we've seen its pull on
Speaker 1: the stars that are around and we see those stars
Speaker 1: orbiting something that isn't there but obviously has a very
Speaker 1: strong gravitational pull. And so globular clusters are a great
Speaker 1: way to see black holes because there are so many
Speaker 1: of these gravitation or probes. If there's a black hole somewhere,
Speaker 1: you should be able to see its effect on the
Speaker 1: nearby stars. You can calculate, like how should these stars
Speaker 1: be moving if there wasn't the black hole, And then
Speaker 1: you can see if there's a deviation from what you
Speaker 1: expect and if that could be explained by putting an
Speaker 1: invisible heavy mass in one spot, and if so, then
Speaker 1: you think you've seen one. So have we found any
Speaker 1: inside a globular cluster. So no confirmed sightings of intermedium
Speaker 1: mass black holes and globular clusters. I know, stay tuned.
Speaker 1: There was one where people thought maybe they saw one
Speaker 1: with four thousand solar masses, but then follow up analysis
Speaker 1: didn't see the same results. And actually you could explain
Speaker 1: all of the star paths without the black hole. And
Speaker 1: so it's a hard thing to do because these things
Speaker 1: are not that close by, and you're looking at individual
Speaker 1: stars in a cluster, you know, thousands of light years away.
Speaker 1: But it's an exciting thing. It's a it's a cool
Speaker 1: new object for us to look into and to ask
Speaker 1: questions about the way stars form and new weird kinds
Speaker 1: of stars and strange conditions for black holes. I mean,
Speaker 1: it seems like a real, just fun happening spot in
Speaker 1: the universe to really put your papers on. As an astronomer. Yeah,
Speaker 1: I think it's really interesting and I love these bits
Speaker 1: of the universe that are sort of left over from
Speaker 1: an earlier time. Now, these things formed more than ten
Speaker 1: billion years ago and they're still around, which gives us
Speaker 1: an opportunity to learn, like what was going on back then,
Speaker 1: because what happened back then is what determined the shape
Speaker 1: and the nature and the content of these things. So
Speaker 1: they really are like a little time capsule of the
Speaker 1: early universe. And everything we're doing in physics about trying
Speaker 1: to understand the universe is about trying to rewind and
Speaker 1: trying to understand how did everything happen. So to do
Speaker 1: that we have to find clues. We have to look
Speaker 1: for places in the universe where stuff is left over.
Speaker 1: You now, this is like the astrophysics analogy of a fossil,
Speaker 1: you know, a little piece of evidence left over from
Speaker 1: an earlier time, or like a living fossil, like a
Speaker 1: Ceila camp. Yeah, exactly, like a living fossil. Unfortunately, there
Speaker 1: probably aren't any aliens living on planets swinging arounds from
Speaker 1: star to star inside a globular cluster. But maybe there are,
Speaker 1: and if so, maybe they could tell us something fascinating
Speaker 1: about what it's like to live inside such a bright environment.
Speaker 1: I'm hoping to find a blob fish inside a globular cluster.
Speaker 1: I think that's why globular cluster sounds gross to me,
Speaker 1: because it resonates with the word blob. You know, every
Speaker 1: time on this podcast, I wanted to say globular cluster
Speaker 1: of almost said blobular cluster. Well, you know it's interesting
Speaker 1: because globular clusters do not deserve that kind of nasty name. Likewise,
Speaker 1: the blobfish actually gets a bad reputation. It does not
Speaker 1: look like that. Have you ever seen the blobfish. It
Speaker 1: looks sort of like a a sad, ziggy exploded blob
Speaker 1: with a frown. Yes, it's not very advertising. No, no,
Speaker 1: it looks like a slimy bloble. That's because it exploded
Speaker 1: when you brought it up from the deep sea and
Speaker 1: it's natural environment. I wouldn't say it's a looker. It's
Speaker 1: not beautiful, but it it looks a lot more solid.
Speaker 1: It just kind of looks like this gray, sort of solid,
Speaker 1: bony fish. But when you bring it to the surface,
Speaker 1: it looks like a blob. And so you know you
Speaker 1: can't trust a glob or a blob by the name. Well,
Speaker 1: it must be very disappointed. You know. It looked at
Speaker 1: itself in the mirror before it leads the house, and
Speaker 1: it's like, I'm looking good, and then it ends up
Speaker 1: looking like a big blob when it's brought up to
Speaker 1: the surface. And they truly do look quite pathetic because
Speaker 1: it looks like they're frowning. But maybe the globular clusters
Speaker 1: and the blobfish can come together and get some better
Speaker 1: pr for themselves. Maybe the aliens that live in globular
Speaker 1: clusters look like blob fish and they'll come here and
Speaker 1: they'll recognize the blobfish as you know, really the people
Speaker 1: they want to talk to. It seems like you'd have
Speaker 1: to be sort of blobular to live in a globular
Speaker 1: cluster because of all those stars tugging on you all
Speaker 1: the time. Like Taffy, your planet would be a bit
Speaker 1: of a blob as well. All right, well, thanks everyone
Speaker 1: for sharing your curiosity with us and taking this tour
Speaker 1: of a fascinating structure inside our galaxy, something that can
Speaker 1: tell us all about the universe and house stars formed
Speaker 1: in the age of our galaxy, and maybe about the
Speaker 1: future of black holes. Episode. When someone says, hey, would
Speaker 1: you like a globular cluster, don't turn your nose up
Speaker 1: at it. It could teach you about the deepest secrets
Speaker 1: of the universe. But please don't use that for your
Speaker 1: next breakfast cereal. All right, everyone, thanks for tuning in,
Speaker 1: see you next time. Thanks for listening, and remember that
Speaker 1: Daniel and Jorge explained. The Universe is a production of
Speaker 1: I heart Radio or more podcast from my heart Radio.
Speaker 1: Visit the i heart Radio app, Apple Podcasts, or wherever
Speaker 1: you listen to your favorite shows.