To the best of my ability. Capitals for emphasis. I split the difference on adding speech slurs.

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TITLE: Why Don’t Gas Clouds in Space Dissipate? Phil Plait, BadAstronomy.com

So in my live chatroom, I was asked: “Why is it that gas clouds, which can be of so low density, they’re basically like laboratory vacuum – how is it that these things don’t just dissipate into space”? And this is actually something that creationists talk about a lot, because they say “oh, stars can’t possibly form from hot gas, hot gas expands, we see this in balloons, right – hot air balloons expand, they can’t possibly collapse to form stars”. And, you know, if a creationist is saying it, it’s probably wrong. That’s the way to bet. So what does this mean? Well, here’s a picture [holds up book] of a really beautiful gas cloud, that I’m getting from the book “Bang!” by Chris Lintott, Patrick Moore and Brian May.. lead guitarist for Queen! That’s so cool – he’s an astronomer! Uhm, this is NGC-2467, that’s just the catalogue name, you can see this gorgeous cloud there. All of this [points] is gas. You can see all the gas.. there’s some dust, dark dust here, some starts lighting it up..
Now basically, some of these gas clouds are called.. a singular is nebula, which is Latin for cloud. Plural is nebulae, with an “e” on the end. And these gas clouds are very, very low density and some of them – the DENSEST of them, might have tens or hundreds of thousands of particles per cubic centimeter. So if I had a mini-marshmallow with [science?], I could show you this, but that’s.. that’s [gestures] about a cubic centimeter.. a salt – eh.. sugar cube, or a mini-marshmallow. And there might only be, you know, maybe a MILLION particles per cubic centimeter inside one of these gas clouds, and you might think “well, a million sounds like a LOT”. But the Earth’s atmosphere [gestures], all around us, has 10 ^ 19 particles, a one with 19 zeroes after it. So this is trillions of times denser – the air is – trillions of times denser than even the densest of these gas clouds in space. So if they’re hot, and they ARE hot, some of them are, you know, thousands of degrees.. although usually they’re cooler than that – hundreds of degrees celsius.. or even lower. Uh, they’re actually.. most of them are actually very cold. Uh, compared to Earth temperatures. Why don’t they dissipate, like hot air does, gas in a hot air balloon? If you were to pop a hot air balloon, right, that hot air will dissipate. The reason they don’t is because these nebulae are immense, okay? It’s not just like a balloon, which might only have a few pounds of air in it. We’re talking about a gas cloud, which is LIGHTYEARS across. And so the total, TOTAL mass of this entire gas cloud can be many times the mass of the sun. These things form stars, they’re star factories, and really big ones, like the Orion nebula or the Tarantula nebula can have thousands, or some of them can have MILLIONS of times the mass of the sun. And all of that gravity added together is what holds that cloud together. THAT’S why they don’t dissipate.
Gas clouds can collide. There’s lots of reasons they can do this. They’re orbiting the center of the Milky Way, some of them are moving faster than others, some of them are on orbits that aren’t in perfect circles, so they intersect and they smack into each other.. And when they do that, they can form shockwaves, and compress and that can form local dense regions inside the gas cloud, and those will collapse to form stars.
We. See. This. Happening. Don’t ever listen, well you can listen to a creationist when they talk, it’s always good.. because then you can find out what NOT to think. Uhm, but when a creationist says “stars cannot form from nebulae, we don’t see it happening”, that is a LIE. We see it happening in all different stages. We haven’t seen ONE star all the way through the process anymore than taking a snapshot of a crowd you will see babies being born, right? It takes a long time for this process to happen. Hundreds of thousands, or millions of years. So it’s not like you can watch one star do it, we’ve only been watching for, you know, a couple of centuries. But we have seen stars, in every different stage of development [shows pictures of this], from gas clouds, to where the stars are starting to form and it’s surrounded by dense gas, to where the gas is collapsing into a disc and forming planets.. We’ve seen these discs with gaps in them [shows picture] where we can see.. we can’t see the planet itself, but we know that there are planets in that disc, carving out these grooves, and forming new planets and gathering mass that way.. to where the planets system is very young and the planets are still glowing from the heat of the formation – all the way up to solar systems like ours! Which is 4.6 billion years old, again despite what SOME people are telling you.
And so, it’s kind of interesting, you get a question like, you know, “what holds gas clouds together” and it actually takes you, if you follow the logic and you follow the physics and you follow the math, it takes you right through from “they don’t dissipate because of their own mass” to “this is how we see stars form”, this is how we see US form.. uh, stars like the Sun forming, they got heavy metals in them like iron and molybdenum and calcium and all that, from stars that explode nearby and seed them with these heavy elements. Those form, and so the Sun gets iron in it from a nearby star that blew up. We see TONS of evidence of this. And so it’s great – this is a great example of where a simple question leads you to very, very profound results.

TITLE: Phil Plait, BadAstronomy.com

To the best of my ability. Capitals for emphasis. I split the difference on adding speech slurs.

TITLE: Why Don’t Gas Clouds in Space Dissipate? Phil Plait, BadAstronomy.com

So in my live chatroom, I was asked: “Why is it that gas clouds, which can be of so low density, they’re basically like laboratory vacuum – how is it that these things don’t just dissipate into space”? And this is actually something that creationists talk about a lot, because they say “oh, stars can’t possibly form from hot gas, hot gas expands, we see this in balloons, right – hot air balloons expand, they can’t possibly collapse to form stars”. And, you know, if a creationist is saying it, it’s probably wrong. That’s the way to bet. So what does this mean? Well, here’s a picture [holds up book] of a really beautiful gas cloud, that I’m getting from the book “Bang!” by Chris Lintott, Patrick Moore and Brian May.. lead guitarist for Queen! That’s so cool – he’s an astronomer! Uhm, this is NGC-2467, that’s just the catalogue name, you can see this gorgeous cloud there. All of this [points] is gas. You can see all the gas.. there’s some dust, dark dust here, some starts lighting it up..
Now basically, some of these gas clouds are called.. a singular is nebula, which is Latin for cloud. Plural is nebulae, with an “e” on the end. And these gas clouds are very, very low density and some of them – the DENSEST of them, might have tens or hundreds of thousands of particles per cubic centimeter. So if I had a mini-marshmallow with [science?], I could show you this, but that’s.. that’s [gestures] about a cubic centimeter.. a salt – eh.. sugar cube, or a mini-marshmallow. And there might only be, you know, maybe a MILLION particles per cubic centimeter inside one of these gas clouds, and you might think “well, a million sounds like a LOT”. But the Earth’s atmosphere [gestures], all around us, has 10 ^ 19 particles, a one with 19 zeroes after it. So this is trillions of times denser – the air is – trillions of times denser than even the densest of these gas clouds in space. So if they’re hot, and they ARE hot, some of them are, you know, thousands of degrees.. although usually they’re cooler than that – hundreds of degrees celsius.. or even lower. Uh, they’re actually.. most of them are actually very cold. Uh, compared to Earth temperatures. Why don’t they dissipate, like hot air does, gas in a hot air balloon? If you were to pop a hot air balloon, right, that hot air will dissipate. The reason they don’t is because these nebulae are immense, okay? It’s not just like a balloon, which might only have a few pounds of air in it. We’re talking about a gas cloud, which is LIGHTYEARS across. And so the total, TOTAL mass of this entire gas cloud can be many times the mass of the sun. These things form stars, they’re star factories, and really big ones, like the Orion nebula or the Tarantula nebula can have thousands, or some of them can have MILLIONS of times the mass of the sun. And all of that gravity added together is what holds that cloud together. THAT’S why they don’t dissipate.
Gas clouds can collide. There’s lots of reasons they can do this. They’re orbiting the center of the Milky Way, some of them are moving faster than others, some of them are on orbits that aren’t in perfect circles, so they intersect and they smack into each other.. And when they do that, they can form shockwaves, and compress and that can form local dense regions inside the gas cloud, and those will collapse to form stars.
We. See. This. Happening. Don’t ever listen, well you can listen to a creationist when they talk, it’s always good.. because then you can find out what NOT to think. Uhm, but when a creationist says “stars cannot form from nebulae, we don’t see it happening”, that is a LIE. We see it happening in all different stages. We haven’t seen ONE star all the way through the process anymore than taking a snapshot of a crowd you will see babies being born, right? It takes a long time for this process to happen. Hundreds of thousands, or millions of years. So it’s not like you can watch one star do it, we’ve only been watching for, you know, a couple of centuries. But we have seen stars, in every different stage of development [shows pictures of this], from gas clouds, to where the stars are starting to form and it’s surrounded by dense gas, to where the gas is collapsing into a disc and forming planets.. We’ve seen these discs with gaps in them [shows picture] where we can see.. we can’t see the planet itself, but we know that there are planets in that disc, carving out these grooves, and forming new planets and gathering mass that way.. to where the planets system is very young and the planets are still glowing from the heat of the formation – all the way up to solar systems like ours! Which is 4.6 billion years old, again despite what SOME people are telling you.
And so, it’s kind of interesting, you get a question like, you know, “what holds gas clouds together” and it actually takes you, if you follow the logic and you follow the physics and you follow the math, it takes you right through from “they don’t dissipate because of their own mass” to “this is how we see stars form”, this is how we see US form.. uh, stars like the Sun forming, they got heavy metals in them like iron and molybdenum and calcium and all that, from stars that explode nearby and seed them with these heavy elements. Those form, and so the Sun gets iron in it from a nearby star that blew up. We see TONS of evidence of this. And so it’s great – this is a great example of where a simple question leads you to very, very profound results.

TITLE: Phil Plait, BadAstronomy.com

Of course any “gas” made of real atoms at the temperatures quoted would be 100% ionized, so it’s deeply misleading to call it gas at all.

Atoms and electrons don’t need to have the same temperature.

IIRC conduction electrons in metals have a Fermi temperature on the order of 10^5 K as the metal is at room temperature. Likewise when you cool atoms to ultra low temperatures it is easier to cool the nucleus, which can interact in many ways, than the electron cloud. So you can have comparably hot gas if there is a restricted interaction.

And that would apply to vacuum conditions. Which is presumably why you AFAIU can see a lot of radiation interaction with dust and partially ionized molecules.

As for astronomers knowledge of plasmas, I find it curious that IIRC most of the easily tractable plasma wave modes are known from astronomy as opposed to say dentists x-ray tubes. Wonder why that is?

the plasma universe

Great, I presume another case of “I have a hammer, what can I use for nails”. Where is the “not for children” label?

Have a good chuckle at the plasma universe here:
http://www.bautforum.com/against-mainstream/

When astronomers see X-rays, they invariably assert that they indicate “hot gas”, and quote whatever absurd temperature it would take to produce the those photons with ideal gas particles bouncing at random. However, the gadget in your dentist’s office doesn’t have a pocket of million-degree “gas”; it’s accelerating electrons in a field. Of course any “gas” made of real atoms at the temperatures quoted would be 100% ionized, so it’s deeply misleading to call it gas at all. Maybe it really is hot, maybe it’s being accelerated; if they were interested they could tell you which.

Plasma, despite the difficulty of the mathematics that describe it, displays some characteristic behaviors. The plasma globe in your museum shop displays several of them. The balls’ current flow is tuned to make the plasma glow pleasingly, but the flux tubes would be there at lower currents, just invisible, as in most astronomical settings. In the solar system we call these tubes “Birkeland currents”, and even many astronomers have been obliged lately to accept that they connect Jupiter’s and Saturn’s poles with their respective moons, as well as the Sun with the Earth’s poles, but of course they still insist they have no notable effect. It’s not hard to get a plasma ball flux tube to oscillate. Plasma structures can oscillate in a seemingly unlimited variety of modes, producing sometimes rapidly varying emissions that astronomers insist can only be produced by the fast rotation of implausibly dense solid bodies.

So, whenever you see an astronomers’ press release that mentions “hot gas”, “dark matter”, or “neutron star”, have a good chuckle at their expense. Someday astronomy students will be obliged to learn and apply real plasma fluid dynamics. In the meantime the telescopes, satellites and space probes are collecting real data that will be useful someday when there is a corps of astronomers equipped to interpret it sensibly.