WEBVTT - Galactic Youngsters

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<v Speaker 1>Welcome to Stuff from the Science Lab from how stuff

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<v Speaker 1>works dot com. Hey guys, and welcome to the podcast.

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<v Speaker 1>This is Alice Madam, science how stuff works dot com.

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<v Speaker 1>And this is Robert Lamb, science writer at how stuff

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<v Speaker 1>works dot com. Today we're doing the third podcast in

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<v Speaker 1>our very first recurring series, and that series has been

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<v Speaker 1>looking at how different celestial bodies get their start. Today

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<v Speaker 1>we're talking about galaxies. If I had to listen to

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<v Speaker 1>the series, I would start with galaxies, then go to stars,

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<v Speaker 1>and then listen to planets, just for heads up if

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<v Speaker 1>you haven't heard any of them. Okay, but not because

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<v Speaker 1>of preference, right, because no, just because because one thing

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<v Speaker 1>that occurred to me when I was actually writing our

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<v Speaker 1>article about that galaxy formation is that this one, I

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<v Speaker 1>think is often overlooked because like the formation of the universe,

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<v Speaker 1>like that, like the Big Bang, like that's so huge

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<v Speaker 1>and mind boggling that you instantly think of that, and

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<v Speaker 1>then things like the formation of a planet or the

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<v Speaker 1>solar system that's a lot closer to home and you

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<v Speaker 1>can relate to that a little better. But a galaxy

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<v Speaker 1>that's just kind of somewhere in between. It's not Yeah,

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<v Speaker 1>I mean, it's enormous. It's on such an enormous scale,

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<v Speaker 1>but not on such a just mind boggling cosmic scale

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<v Speaker 1>that people set around and I think, ponderate unless you're

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<v Speaker 1>you know, like actually a cosmologist or after physicist. So

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<v Speaker 1>we have to back up to the Big Bang. But

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<v Speaker 1>we're not going to get into the Big Bang. Um.

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<v Speaker 1>So it is a galaxy. A galaxy, Well, it is

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<v Speaker 1>the largest structure in the universe, and it binds billions

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<v Speaker 1>or even trillions of stars together in a big gravitational yoke.

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<v Speaker 1>What else is in galaxies besides stars? Well, you've got

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<v Speaker 1>planets yep, yeah, cats, dog, Well that's on the smaller scale.

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<v Speaker 1>But no, you've got cosmic dust, vast clouds of gas, um,

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<v Speaker 1>you know, comets, like every thing really if you can

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<v Speaker 1>name it, it's in the galaxy, including dark matter, yes,

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<v Speaker 1>dark matter, dark energy, all that good stuff. So let's

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<v Speaker 1>rewind roughly fourteen billion years ago, two win galaxies got

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<v Speaker 1>their start. Yeah, back to the Big Bang, which is

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<v Speaker 1>our best theory about how all this came about. And

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<v Speaker 1>I like to think of and this is a this

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<v Speaker 1>is a very basic analogy, but I like to think

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<v Speaker 1>that this way. Imagine you have a map of the

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<v Speaker 1>universe right spread out on a table. Yes, now, no, now,

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<v Speaker 1>imagine the entire map like wadded up into a single

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<v Speaker 1>ball of paper. But a ball of paper like just

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<v Speaker 1>microscopic and size, you know, just ridiculously small. Yeah. I've

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<v Speaker 1>come across a different a few different estimations of how

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<v Speaker 1>big or how small via that singularity was. Some people

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<v Speaker 1>say it's about the size of a dime. Other people

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<v Speaker 1>say it's smaller than an electron. Yeah, yeah, you see it.

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<v Speaker 1>See size estimation is bearing. But whatever the exact size,

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<v Speaker 1>a whole lot, like everything, the entire universe crunched down

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<v Speaker 1>to one unimaginably small because whether we're talking about the

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<v Speaker 1>size of a quarter or the size of a basketball

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<v Speaker 1>or the size of an atom. Um that's a lot

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<v Speaker 1>of universe packed into one god stopper. And then it

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<v Speaker 1>then it expands and yeah, and you have hot matter,

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<v Speaker 1>it ends up cooling. But but nothing has there's not

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<v Speaker 1>really any structure. It's not like wham, now we have

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<v Speaker 1>you know, galaxies and planets, etcetera. You just have a

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<v Speaker 1>lot of like it's like raw uncooked galaxy. No not,

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<v Speaker 1>I mean raw uncooked universe out there. Yeah, you have

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<v Speaker 1>the ingredients. You just have a lot of gas, a

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<v Speaker 1>lot of dust just floating out there. So how those

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<v Speaker 1>ingredients evolve in somewhere than a hundred billion galaxies. Well,

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<v Speaker 1>there are two bodies of theories according to NASA about

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<v Speaker 1>how this came about, all right. There are bottom up

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<v Speaker 1>theories and they're top down theories, and this sort of

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<v Speaker 1>sounds like what they are. Yeah, you know, it's it's

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<v Speaker 1>kind of like in a bottom up theory, the gas,

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<v Speaker 1>all this gas and dust collapses and compresses into a

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<v Speaker 1>clump about the size of a million sons. And that's

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<v Speaker 1>that's starting small for something that's gonna become, you know, galaxies.

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<v Speaker 1>All right. These clumps then merge to build galaxies. All right.

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<v Speaker 1>Again bottom up, and as we touched onto some previous podcasts,

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<v Speaker 1>this is acretion. This is the process of little particles

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<v Speaker 1>coming together forming slightly larger particles which then have a

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<v Speaker 1>gravitational pull on other particles. It's like a snowball going

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<v Speaker 1>down a hill. Right. If you're listening to these podcasts,

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<v Speaker 1>there's definitely a theme of acretion running through all of them. Yeah.

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<v Speaker 1>So yeah, this one is just that the gas collapse

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<v Speaker 1>into enormous but cosmically small clumps which then end up

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<v Speaker 1>forming larger clumps which become galaxies. And then you have

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<v Speaker 1>your top down theories, which of course start big. And

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<v Speaker 1>the school of thought is going to argue that the

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<v Speaker 1>resulting clumps were each of us of multiple galaxies, and

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<v Speaker 1>then the size got too big to manage, and they

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<v Speaker 1>broke down into our individual galaxy, like the Milky Way galaxy.

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<v Speaker 1>And if you follow this train of thought, then you

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<v Speaker 1>get an understanding of why galaxies occur in clusters, but

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<v Speaker 1>either way bottom up, top down. The resulting clumps then

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<v Speaker 1>collapsed into proto galaxies, which consisted of dark matter and

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<v Speaker 1>hydrogen gas. Yeah, and then the hydrogen then falls to

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<v Speaker 1>the center of the proto galaxy, wanted the dark matter

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<v Speaker 1>remains as an outer halo surrounding everything. You know. When

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<v Speaker 1>we're researching this podcast, it came across another interesting theory,

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<v Speaker 1>that of hierarchical formation, in which merging of established galaxies

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<v Speaker 1>occurs too, And so the story on it was this.

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<v Speaker 1>Researchers from University of Switzerland saw some merging galaxies in

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<v Speaker 1>a group dubed s g oh Dash one two, which

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<v Speaker 1>is a very sexy name for those galaxies. Right, and

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<v Speaker 1>roughly four billion light years away, and they reported their

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<v Speaker 1>findings in the August two thousand eight issue of the

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<v Speaker 1>Astrophysical Journal Letters. Have you read that, lady, Robert so Um,

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<v Speaker 1>they were saying that smaller galaxies were destined for one

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<v Speaker 1>another courtesy of the mutual gravitational attraction, and then they

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<v Speaker 1>formed these massive galaxies. Okay, so that was that was

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<v Speaker 1>their take on it, and their theory also stipulated that

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<v Speaker 1>star formation would primarily occur when galaxies were small, but

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<v Speaker 1>they would gather all their mass during the mergers. But

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<v Speaker 1>we'll get to star formation in the second. So astronomers

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<v Speaker 1>recognized to basic shapes for galaxies. There's elliptical and then

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<v Speaker 1>their spiral and we're spiral galaxies, but we're technically a

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<v Speaker 1>spiral bar galaxy. Yeah right, a lot of them are

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<v Speaker 1>actually yeah, well the spiral galaxies are essentially we're spiral galaxy.

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<v Speaker 1>And you also have you disorganized galaxies, which are kind

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<v Speaker 1>of my favorite. Which, um, if you think about two

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<v Speaker 1>galaxies merging, um, maybe when they first merged, they they're

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<v Speaker 1>disorganized and then they sort themselves out into their neat

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<v Speaker 1>spiral shape for their elliptical shape, but who knows, they're

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<v Speaker 1>not sure of that. And then there's a third type

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<v Speaker 1>of galaxy, UM, the disorganized galaxy, which you have to

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<v Speaker 1>kind of identify with this kind of galaxy, right, um,

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<v Speaker 1>that disorganized but no, no, no no, that was not a

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<v Speaker 1>personal rabbert. Although are you disorganized? No, just I'm organized,

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<v Speaker 1>but in a disorganized fashion at times. Depends on what

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<v Speaker 1>I'm doing. Well, they say, the people who have very

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<v Speaker 1>organized deaths have too much time in their hands, right yeah.

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<v Speaker 1>And then some people don't don't decorate their offices at all,

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<v Speaker 1>or their cubicles. That's just I don't know if that's

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<v Speaker 1>not being if that's being really organized, or that's just

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<v Speaker 1>being lame. I know somebody at work who had decorated

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<v Speaker 1>their cubicle and then took it down in protest when

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<v Speaker 1>she had a bad day one day, and she never

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<v Speaker 1>put it back up. I don't think it's an odd

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<v Speaker 1>form of protests. It didn't convey anything to me. Attachment detachment.

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<v Speaker 1>I think say these UM, so you have your your spirals,

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<v Speaker 1>you have your ellipticals, and then UM, at least initially,

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<v Speaker 1>emerged galaxies might not like these two main shapes. They

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<v Speaker 1>might be disorganized, but eventually astronomers believe that the merge

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<v Speaker 1>galaxies result in an elliptical galaxy. As such, our Milky

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<v Speaker 1>Way has probably never emerged with another galaxy, because again

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<v Speaker 1>it's that's hard spiral shape. But the massive elliptical galaxies

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<v Speaker 1>found at the center of galaxy clusters are probably the

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<v Speaker 1>result of some serious cosmic mashups. Yeah, it's just it's

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<v Speaker 1>almost it's kind of like accretion on a huge scale,

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<v Speaker 1>with just galaxies running into each other, just becoming this big,

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<v Speaker 1>enormous thing. But the interesting thing that I was reading

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<v Speaker 1>about is just because two galaxies passed close by, they

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<v Speaker 1>don't have to merge, they don't have to make this

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<v Speaker 1>one big galactic family. Rapidly moving ones I read can

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<v Speaker 1>pass through one another, sort of like ghosts almost, but

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<v Speaker 1>the slower moving ones seemed to be likely to get

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<v Speaker 1>all up in each other's business and merge. Something to

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<v Speaker 1>keep in mind when we went eventually merged with Andromeda. Right, indeed,

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<v Speaker 1>so let's about star formation and the elliptical and spiral galaxies. Okay,

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<v Speaker 1>how does that figure in? All? Right? Well, stars develop

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<v Speaker 1>inside a proto galaxy when the cloud, when the clouds

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<v Speaker 1>of gas mix and collide, so of all the stars

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<v Speaker 1>in a proto galaxy form at once, and the mature

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<v Speaker 1>galaxy essentially retains the roundest shape of the proto galaxy

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<v Speaker 1>and becomes an elliptical galaxy. Spiral galaxies, however, occur when

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<v Speaker 1>the stars inside the proto galaxy or as at different intervals,

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<v Speaker 1>so you know, they're not popping up all at once,

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<v Speaker 1>They're happening at different times, and the gas between the

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<v Speaker 1>developing stars continues to collapse, and the resulting gravitational differences

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<v Speaker 1>manhandle the proto galaxy stars, the dust, and the gas.

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<v Speaker 1>What do you know? This motion starts to force everything

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<v Speaker 1>into a rotating disk, and additional differences in gravity result

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<v Speaker 1>in the spiral arms. It's kind of like when I

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<v Speaker 1>was trying to make sense of this, I thought of

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<v Speaker 1>it in terms of, like imagine like with an elliptical galaxy,

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<v Speaker 1>Like imagine a town where everybody's the same age, you know,

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<v Speaker 1>only like everybody's like thirty five, so you only have

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<v Speaker 1>the kind of places thirty five year olds hang out,

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<v Speaker 1>like no, you know, no place where like teenagers roll

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<v Speaker 1>or where it's one of those over fifty communities. That's

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<v Speaker 1>what it is. Yeah, Yeah, that kind of thing whereas

0:10:10.679 --> 0:10:13.440
<v Speaker 1>elliptical has would like an elliptical galaxy is like a

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<v Speaker 1>town where you have guys of all ages with his

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<v Speaker 1>diversity and conflict spinning everything around, so much more interesting

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<v Speaker 1>place to live if you're into that. Yeah, so that's

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<v Speaker 1>my convoluted analogy of the day. Did you know that

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<v Speaker 1>the Milky Way galaxy is rotating and will complete a

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<v Speaker 1>revolution in two fifty million years, like a galactic year?

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<v Speaker 1>That would be okay, Yeah, it's a lot longer than

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<v Speaker 1>one of those restaurants that rotates at the top of

0:10:41.120 --> 0:10:45.360
<v Speaker 1>the hotel will market on the calendar. Put them in

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<v Speaker 1>Google calendar alert. Galactic year just finished. Well, said Robert.

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<v Speaker 1>So that was kind of a light intro to galaxy formation.

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<v Speaker 1>If you guys want to hear more about the mechanics

0:10:57.760 --> 0:11:00.480
<v Speaker 1>of galaxy formation or get deeper into the topic, send

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<v Speaker 1>us an email at science Stuff at hows to first

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<v Speaker 1>dot com and we'll see what we can do. For instance,

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<v Speaker 1>like bottom up theories, there are a number of bottom

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<v Speaker 1>up theories. There are a number of top down theories,

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<v Speaker 1>but they're a number of steps. Yeah, and but these

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<v Speaker 1>are the basics, and obviously there's a lot of formation

0:11:13.520 --> 0:11:17.840
<v Speaker 1>that continues um, you know at lower levels within the galaxy,

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<v Speaker 1>which we've touched down on in uh in other podcasts. Yeah,

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<v Speaker 1>as always, you can take galaxies into the search part

0:11:24.360 --> 0:11:26.920
<v Speaker 1>on how Stuff Works homepage and see what good stuff

0:11:26.920 --> 0:11:30.400
<v Speaker 1>that brings up. They're gonna see how galaxies work. Maybe

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<v Speaker 1>whether space has a shape? This is a good one.

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<v Speaker 1>Is there a hole in space? That's another one that

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<v Speaker 1>we have, Yeah, or the big bank very written by Strickland.

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<v Speaker 1>But I think you did a good job. Hey, and

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<v Speaker 1>we also have a Facebook and a Twitter account now,

0:11:42.559 --> 0:11:46.920
<v Speaker 1>so um you can check those out. Just to search

0:11:47.000 --> 0:11:50.000
<v Speaker 1>for stuff in the science lab or lab stuff on

0:11:50.080 --> 0:11:52.840
<v Speaker 1>Twitter on Twitter or Facebook and then lead you right

0:11:52.920 --> 0:11:57.280
<v Speaker 1>to us, and uh we update that thing pretty pretty regularly.

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<v Speaker 1>Come see what science the topics we're thinking about this week.

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<v Speaker 1>So that's all the galactic goodness we have for you

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<v Speaker 1>guys today. Thanks for listening. For more on this and

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<v Speaker 1>thousands of other topics. Is it how stuff works dot com?

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<v Speaker 1>Want more how stuff works? Check out our blogs on

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