C.G., I can see your frustration, I really can. I'm a layman myself (and I BEG those with more expertise to correct the many mistakes I'm probably going to make trying to explain this layman to layman).
First C.G., the thing is, what these guys are trying to get across is that the very bottom line fundamental basis of your questions seem to be grounded within a conceptual framework that's got nuthin to do with how "the big bang" is thought to have worked.
For instance - you keep talking about gasses, and how gasses behave. But early in the b.b. THERE WEREN'T ANY GASSES YET.
To have a gas you have to have atoms. A few instants after the b.b. started, pressures were SO high, and energy levels were SO dense, that structures like atoms weren't possible. Even "subatomic particles" like electrons, protons, neutrons, etc. hadn't formed yet.
Photons (light) couldn't even exist under conditions like that.
What you had, at first, was a kind of homogeneous energy "soup".
That "soup" had to expand and cool a bit before structures like photons could essentially precipitate out, and it had to expand and cool a bit more before things like electrons, protons, neutrons etc. could precipitate out, and expand and cool even more before subatomic particles could begin to condense into atoms.
QUESTION FOR THE ADVISORS:
Have I got that right - i.e. no atoms or photons at first, if so...
How far into the b.b. did photons start to form?
How much later before atoms and gasses, of any kind, were able to form?
"Gas naturally expands unless there is a substantial mass somewhere to pull it together. Fick's law of Diffusion. Then, once the gas started to somehow condense, it somehow convinced itself to stop condensing. Either the Big Bang should have produced an expanding cloud of gas, or it would have produced an expanding cloud of gas that magically condensed, and kept condensing until there was another singularity. This would kind defeat the purpose of a big bang. Also, I simply cannot come up with another reasoning other than magic that tells us how subatomic particles were going supersonic speeds and expanding in every direction, but somehow came together. In a fraction of a second, the particles would have been too far away from each other for the strong and weak nuclear forces to do their job."
Man. No 'fense C.G., but you've got all this SO tangled up that I literally don't know where to start. I really don't. I'm not trying to put you down, or embarrass you, heck it's not like I "get" much of this either but, sheeesh. Where to start?
Maybe piece by piece?
"Gas naturally expands unless there is a substantial mass somewhere to pull it together."
What you're missing here is that there IS "a substantial mass somewhere to pull it together". And that would be the mass of the cloud of gas itself.
Picture a cloud of hydrogen in deep space. Picture a single hydrogen atom at its edge that flies away from the cloud. That atom isn't going to just go on forever right? I mean, it's got a finite amount of momentum to keep it going, but the gravitational attraction of ALL the atoms in the cloud of hydrogen gas it left behind are going to be trying to pull that stray atom back - no matter how far away it gets.
The farther it gets from the cloud, the less the gravitational attraction of all the atoms in that cloud are going to be pulling on it, but that gravitational attraction is never - ever - going to become zero.
The mass of the gas cloud forms essentially a kind of gravitational bowl where, the walls of the bowl start out quite steep, and get less steep the farther you get from the center of the bowl, but the bowl NEVER gets to a point where it's flat, the stray atom is ALWAYS essentially going "up hill", with the hill always getting less and less steep, BUT NEVER FLAT.
Eventually, since the stay atom started out with a very finite amount of momentum, it's going to run out of steam, stall, and start to fall back toward the center of mass of the gas cloud it came from - unless...
There's another gas cloud out there someplace, in which case the stray atom could get caught in the gravity well of THAT cloud of hydrogen gas, in which case the stray atom would wind up getting sucked into that second cloud. Got it so far?
"Fick's law of Diffusion." Has nothing at all to do with any of this. Seriously. Fick's laws cover how, and how quickly, things mix by diffusion.
"Then, once the gas started to somehow condense, it somehow convinced itself to stop condensing."
No! No it wouldn't. In fact this is exactly how stars form.
With a little gas, you wind up with a nebula. A gas cloud. That acts like a bowl full of marbles bouncing off each other. And just like the example above, any atom at the edge that flies off into space, will only go as far as its momentum will carry it from the center of mass of the gas cloud, until it runs out of steam, stalls, and falls back into the gas cloud.
With enough gas, a lot of gas, the condensing doesn't stop.
The more atoms that get drawn to the center of the gas cloud, the steeper the gravity well gets.
The steeper the gravity well gets, the more atoms get drawn in, and the more the pressure goes up as they start piling up on each other.
The more the pressure goes up, the more the temperature of the gas goes up.
If this keeps up, eventually the pressures and temperatures get SO high that nuclear fusion begins, and you get - A STAR - a gas cloud of hydrogen maintained in a fine balance between fusion trying to drive it apart, and gravity trying to crush it together.
And this is exactly what the big bang produced.
Once it had cooled enough for things like atoms to exist, what you wound up with is a HUGE cloud of mostly hydrogen gas with enough momentum to keep expanding - for a while.
But that cloud wasn't absolutely perfectly homogenous. There were imperfections in the mass distribution. Areas of very slightly higher and lower density.
So it started clumping up as it continued to expand.
It started forming into clumps of hydrogen gas with each clump competing for and stealing hydrogen atoms from each other as in the first scenario I described.
(an atom only gets so far from the gas cloud - unless... it gets grabbed by another gas cloud)
The clumps condensed into galaxies. Clumps within the galaxies formed nebulae. Many of the nebulae collapsed into stars, etc.
WHERE "DARK ENERGY" COMES INTO ALL THIS.
O.K., at first all this pretty much matched what we could see through telescopes etc.
The b.b. had produced a vast cloud of expanding hydrogen gas that, because it wasn't PERFECTLY homogenous, started clumping up into galaxies and stars as it continued to expand.
So now one of two things would happen in the long term (as in billions of years from now).
1) The big bang expansion had SO much inertia behind it that this cloud of clumped up galaxies and stars would continue to expand forever, getting cooler and thinner, as it went. Eventually even individual stars would get so far apart that you wouldn't even see any other stars in the night sky. The night sky would just be black. Eventually even the stars, all of them, would burn-out, cool, and the entire universe would under go what was termed "heat death".
2) The big bang's expansion DIDN'T have enough inertia to keep expanding forever. Eventually, just as in that first example I gave of the stray atom shooting away from a gas cloud, the expansion would run out of steam (momentum), stall, and the entire universe would start to fall back into what was referred to as "The Big Crunch". Eventually all mass and energy would be compressed back into a single point to produce another Big Bang, and this process would repeat for all time - Big Bang, stall, Big Crunch - Big Bang, stall, Big Crunch - Big Bang, stall, Big Crunch, and that would repeat for all time because since energy can't be created or lost, and there was no place for the energy to go, this process would repeat - literally - forever.
So the BIG question a few decades ago was - WHICH IS IT? Big Crunch leads to Big Bang and repeat for all time? Or Heat Death?
The answer lie in measuring - to a very exact degree - how quickly the expansion of the universe was slowing.
If the expansion was slowing quickly - that would imply Big Crunch.
If the expansion was not slowing quickly enough - that would imply Heat Death.
So with much better instruments those measurements were made and, once the results were in...
IT HIT THE FAN BIG TIME BABY!
Turns out, to literally EVERYONE'S amazement, the expansion wasn't slowing at all, IT WAS ACCELLERATING!
Something HAS to be powering that accelerated expansion. For now it's being called "Dark Energy". And "Dark Energy" ISN'T just a fudge factor or a cheat. It's VERY real, it's right there in front of our eyes. We didn't expect to see this - but hey - it's RIGHT THERE in front of us. We can't just ignore it. It's effects can be clearly seen, and measured, and analyzed, but this is a very new wrinkle in things nobody expected to have to grapple with. It's just a new piece of the puzzle to be placed in the picture. But for now, and just for now, NOBODY knows where Dark Energy comes from - yet.
