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Anonymous Mon 17 Aug 11:55:46 2020 No.12017763 View Reply Original Report

Quoted By: >>12017775 >>12017780 >>12017865 >>12018284 >>12018291 >>12018296 >>12018331 >>12019001 >>12021663

How can gas ever coalesce into stars when the very nature of how gas behaves would suggest that shit would continue to spread out to the (in)finite universe?
>inb4 gravity
Gravity is a force that acts between one body and another. A cloud of gas is really just a collection of many, many atomic/molecular bodies. None of these invisibly small bodies have any chance of having enough gravitational force to attract the rest.

Anonymous

Anonymous Mon 17 Aug 2020 11:58:30 No.12017775 Report

Quoted By: >>12017820

>>12017763
gravity is cumulative, the gravity between any one given particles is small, but a given particle is being attracted to multiple particles at once

Anonymous

Anonymous Mon 17 Aug 2020 11:59:47 No.12017780 Report

Quoted By:

>>12017763
holy based

Anonymous

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Anonymous Mon 17 Aug 2020 12:15:48 No.12017820 Report

Quoted By: >>12017838 >>12017849 >>12018003 >>12020639

>>12017775
I fail to see how that would change things much.
The particles in the inner part of the cloud would be pulled towards the particles of the outer cloud, and the outer part of the cloud would be pulled towards the inner. That would effectively cancel out, would it not? Even if you include differing masses of the particles (when the first stars were forming, the heaviest form of matter that existed at the time was just helium, right?) and possible irregularity of said particles' distribution in the gas, I don't really see that causing the cloud to collapse in itself, especially when on top of all of that the gas is seeking equilibrium and naturally wants to spread out.

s Mon 17 Aug 2020 12:23:22 No.12017838 Report

Quoted By: >>12017849 >>12017912

>>12017820
no it wouldnt cancel the inner cloud has higher density

Anonymous

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Anonymous Mon 17 Aug 2020 12:24:13 No.12017840 Report

Quoted By: >>12017912

>gravity only acts on solids

Anonymous

Anonymous Mon 17 Aug 2020 12:29:13 No.12017849 Report

Quoted By: >>12017912 >>12024078

>>12017820
see>>12017838
the clouds aren't perfectly uniform and equally spaced. it doesnt cancel out, there is a net positive acceleration towards the center

Anonymous

Anonymous Mon 17 Aug 2020 12:32:30 No.12017857 Report

Quoted By: >>12017912

this is not really my field of competence, but the way i see it there are 2 ways to explain:
1) lets say you have an initial overdensity region which occured purely from random motions of particles, now each particle is preferentially attracted to that 'clump' and if its total energy (i.e. kinetic/thermal - potential w.r.t. to the clumps gravity well) is negative, it will orbit the clump. When it passes through its periapsis, it effectively increases the clump's mass (it's a nonlinear effect) meaning more particles are dragged in, further increasing the clump's density...
then after a while you both have a huge mass of gas and also it becomes very hot because the particles close to the center (assuming they haven't lost that much of their energy to other particles) move very fast i.e. the gas is very hot -> boom iginition
2) if you know friedmann's equation (self-gravitating fluid essentially) then there is a limiting density above which the matter collapses gravitationally (not in the black hole sense, just that 'on average' it experiences 'pull' as opposed to 'push'). Then the clump grows like I've explained above

Anonymous

Anonymous Mon 17 Aug 2020 12:35:57 No.12017865 Report

Quoted By: >>12017912

>>12017763
Gas spreads out on Earth because the particles are moving around very fast. In space the particles don't have much energy so gravity is the dominant force.

Anonymous

Anonymous Mon 17 Aug 2020 12:39:53 No.12017872 Report

Quoted By:

Helium atoms don't repel each until they are extremely close together.Meaning by the time they do repel each other it's too late and the cloud is big enough for gravity too snowball into a star.

Anonymous

Anonymous Mon 17 Aug 2020 12:56:09 No.12017912 Report

Quoted By: >>12017961 >>12017971

>>12017840
Is that a picture of you? I never said that.
>>12017838
>>12017849
>>12017857 [1)]
I already addressed that in my post. Gas spreads out; there is nothing suggesting the inner cloud would necessarily be denser unless heavier particles just happened to be there; and even so they are still just that, particles. That's not even mentioning the fact that nebulae are literally less dense than the vacuums we can create on Earth.
>>12017865
Maybe, but don't most nebulae have stars in side them, which is the reason we can see them at all? Wouldn't that provide some energy? What about the gas clouds that come from supernovae? Or the gas in the beginning of the universe when everything was order of magnitudes hotter than it is now?

Anonymous

Anonymous Mon 17 Aug 2020 13:15:21 No.12017961 Report

Quoted By: >>12017965 >>12021692

>>12017912
the fact that there is a cloud implies that the cloud is denser then the not-cloud around it.

all the gas will be attracted to the clouds gravitational center, but start orbiting this center due to minute spin buildup/turbulence. it will form clumps, those clumps will form bigger clumps, ect, star.

>The particles in the inner part of the cloud would be pulled towards the particles of the outer cloud, and the outer part of the cloud would be pulled towards the inner.

For ease of imagining, think of an evenly spread out gascloud in the shape of a sphere for a second.

the particles at the centre of the shere are pulled from all sides evenly by all the particles around it, so they stay in place, the particles on the edges of the cloud are pulled only to the gravitational centre, since on one side they have gas with gravity, and on the other they have just void.
This condenses the cloud more and more towards the centre.

>when on top of all of that the gas is seeking equilibrium and naturally wants to spread out.

gas only does that under pressure, but by the time it experiences any pressure from gas particles bouncing around enough to make the gas want to spread out, there is already enough gravity to overcome this. (and if there is not enough gas to overcome this pressure through gravity at any point in the star formation, the cloud will spread out again, being unfit for star formation)

So yes, that happens, but also it sometimes "not" happens when the gas cloud is large enough.

Anonymous

Anonymous Mon 17 Aug 2020 13:17:04 No.12017965 Report

Quoted By:

>>12017961
>So yes, that happens, but also it sometimes "not" happens when the gas cloud is large enough.

For the same reason all stars dont just burst into clouds of gas because their gravity cannot hold their pressure together.

Anonymous

Anonymous Mon 17 Aug 2020 13:18:43 No.12017971 Report

Quoted By: >>12017973

>>12017912
firs of all, whether a collection of particles is correctly treated as a gas (i.e. a fluid) depends on the scale of the problem, the ideal gas law and such don't apply if the scale of the object (e.g. a nebula) is less than or on the order of the mean free path of a particle.
now that we know that particles in a very tenuous medium can approximately be discovered as having no collisions, you should be able to see how simply due to the random motion of particles in straight lines density (number of particles per a test volume) can become different in different parts of space. in fact AFAIK this is exactly the model they use to explain how larger structures of the universe (the cosmic web with the galactic clusters) came about following inflationary epoch, this can in fact be modeled by a gaussian density field
also take a look at this
https://en.wikipedia.org/wiki/Friedmann_equations#Density_parameter
the critical density is several orders of magnitude lower than can be achieved in ultra-high vacuum chambers on earth, yet a clump of matter with density higher than this will tend to collapse (heating up in the process as the gravitational energy is converted to thermal)

Anonymous

Anonymous Mon 17 Aug 2020 13:19:48 No.12017973 Report

Quoted By:

>>12017971
>approximately be discovered
treated of course

Anonymous

Anonymous Mon 17 Aug 2020 13:32:16 No.12018003 Report

Quoted By:

>>12017820
Because the inner particles are compressed more so because of the increase in density the mass per square meter increases. This creates a stronger gravitational pull.

Anonymous

Anonymous Mon 17 Aug 2020 15:23:44 No.12018284 Report

Quoted By:

>>12017763
Because it wasn't all gas. There were the same rock and slush that coalesced to form the planets as well in the disk.
Your densest stuff is going to sink to the middle because of the friction and gravity, which is going to attract more gas in a feedback loop.
Eventually you have enough mas to crush atoms beyond the electron rebound limit and fusion starts, which creates an outward pressure that blows away any more infalling dust and gas.

Anonymous

Anonymous Mon 17 Aug 2020 15:25:44 No.12018291 Report

Quoted By:

>>12017763
It's all fake.

Anonymous

Anonymous Mon 17 Aug 2020 15:29:36 No.12018296 Report

Quoted By:

>>12017763
Gravity

Anonymous

Anonymous Mon 17 Aug 2020 15:42:19 No.12018331 Report

Quoted By:

>>12017763
>None of these invisibly small bodies have any chance of having enough gravitational force to attract the rest.
since when?

Anonymous

Anonymous Mon 17 Aug 2020 19:18:39 No.12019001 Report

Quoted By:

>>12017763
You're not appreciating how massive these gas clouds are. Big enough to dominate spacetime

Anonymous

Anonymous Tue 18 Aug 2020 08:47:09 No.12020639 Report

Quoted By:

>>12017820
You lack imagination.
You are attracted to the earth, which you may see is made of individual little bits of dirt and stuff. But you understand that since you are equally attracted to all the bits of dirt at a given distance, it averages out so that you are attracted toward a point in the center in between all the bits of dirt. And each but of dirt is also attracted to that center. Hence the dirt ball.

Anonymous

Anonymous Tue 18 Aug 2020 08:51:52 No.12020641 Report

Quoted By:

In the beginning, the ripples of the big bang and uneven cooling would bring the first hydrogen atoms together enough for gravity. As stars were born and died, they made heavier solid elements. This dust collages through electrostatic charges and then gravity kicks in. The dust balls gather gas for the next generations of stars.

Anonymous

Anonymous Tue 18 Aug 2020 16:18:18 No.12021663 Report

Quoted By:

>>12017763
It's gravity. Just because you are dumb enough to believe it isn't gravity, doesn't mean it isn't gravity.

Anonymous

Anonymous Tue 18 Aug 2020 16:25:27 No.12021692 Report

Quoted By:

>>12017961
Better than I'd have said it.

Anonymous

Anonymous Wed 19 Aug 2020 05:05:43 No.12024078 Report

Quoted By:

>>12017849
This is a good description.

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