Why is Space a Vacuum

[Suicide Junkie]

The amount of matter in the universe is just very small compared to its volume.
On the order of 10^-28 kg per cubic meter.
The mass of a proton is 1.67 x 10^-27.

Now, most of the mass is also concentrated in stars, planets and whatnot, so the matter left to spread over deep space is even less.
Interplanetary space has a bit more than deep space, mot not too much.

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The oxygen molecules from your tank are all travelling quite fast in random directions, and since there are no longer any walls to hold them in, the random motions cause them to spread out quite quickly. Gravity will deflect them somewhat towards the nearby large bodies, but the velocity of those oxygen molecules is surprisingly high.

After they rapidly leave your immediate vicinity, they'll spread out around the solar system and the concentration drops to undetectable levels again.

A kilogram of oxygen has 2x10^25 molecules, but a cubic AU (radius of earth's orbit) has 3x10^33 cubic meters in it.
Evenly spaced and at orbital speeds, you'd bump into those lost molecules rarely enough to count each meeting.

[Suicide Junkie]

The densest nebulae have about 10,000 molecules per cm^3.
The air we breathe has 10^19.

If they get too dense or cool, then they'll collapse into star clusters.

[Paul1980au]

Fully understand the vacuum is because there is a lack of any heavier elements hydrogen and helium making up 99.999% of the volume of interstellar space.

[Fyron]

Umm... invert that number and then divide some really huge exponentials into it and you have a more accurate number on the volume of space taken up by hydrogen and helium. Now, the vast majority of matter is made of those 2 elements, but the vast majority of space is empty.

[narf poit chez BOOM]

When molecules move and collide with something, they exert force on it, transfering some kinetic energy. This is what pressure is, a measure of the average force that the matter is exerting upon a surface, an object, a probe, etc.

ah, that explains it. so, if you froze something to near 0 kelvin, you could compact it alot?

[Phoenix-D]

Originally posted by Paul1980au:
Fully understand the vacuum is because there is a lack of any heavier elements hydrogen and helium making up 99.999% of the volume of interstellar space.

Fyron is correct..if this was true, letting oxygen out into space and then lighting a match would result in an explosion. It doesn't.

Hydrogen and helium make up the majority of elements because they are the simplest and take the least mass. For every, oh, carbon atom you could have TWELVE hydrogen atoms. For the metals and heavy radioactive elements, it gets even worse.

EDIT: and yes, things near 0K can be more compact. Note the can. Because as you compact them you decrease the volume and increase the pressure. The result of -that- is an increase in heat.

[ January 28, 2004, 05:13: Message edited by: Phoenix-D ]

[Fyron]

Originally posted by narf poit chez BOOM:
ah, that explains it. so, if you froze something to near 0 kelvin, you could compact it alot?

Yes, because the molecules would not hardly be moving at all. And what P-D said. The increase in heat from compacting stuff comes from the increase in the kinetic energy transfered per unit area/volume, hence increased pressure. Same amount of energy, just in a smaller area/volume. But then the increased heat causes the molecules to move faster, so they get away from each other and decrease the volume again, unless you keep them trapped. Keep in mind that temperature is a measure of the average root mean square velocity of the molecules in a given volume, which is a direct result of their average kinetic energy.

[ January 28, 2004, 05:22: Message edited by: Imperator Fyron ]

[Atrocities]

Ok the reason I brought this up was A) I honestly did not understand the nature of space as a vacuum, that being explained now, and thank you all, I move on to my other thought.

Nebula's are basically gasses being held in place by a gravitational force or other. These nebula can be pretty much any gas combination. So to turn this toward an SEIV topic, would it be possible to make a component that could use the inherent gasses of a nebula and convert them into energy for a ship or say stationary Starbase where a Q-reactor was not present?

The idea I have in mind is to make nebula system even more of a strategic asset then they currently are.

If you could mine a nebula for resources and use those resources for production or supply generation depending upon the component used, then nebula systems become far more useful in a game. You would want to protect them from nebula busters or other.

That being said, why not consider the possibility of mining the entrance to a black hole. We all know that matter is pulled into a black hole and super compacted to extremely dense material, so why can we not mine that material? Of course this would require a means to remain neutrally buoyant against the gravitational event horizon of a gravity well, and components to mine for resources at an accelerated rate. The cost would be high, but the pay off would be well worth it.

Also, as a twist to the normal use of a nebula, have breathable ones where you could establish colonies similar to ring worlds, but more along the lines of platforms or rafts that a colony can be built upon. So long as the nebula was breathable gas, IE hydrogen, oxygen, etc it could support a limited number of these colonies.

What about randomly forming nebula? Basically from what I recall from the discovery channel, a nebula is could be formed when a star explodes and the gasses within it are released. There is still enough density from the Stars core to keep the ever expanding gasses held together via gravity, thus creating a nebula. Kind of like a big bag of sun gasses held together and prevented from dissipating by what was left of the stars core and its gravity. So a nebula is formed, why can it not be used as a source for material or a home for a race that can live off of the gasses contained within?

These were just some thoughts I had about trying to make nebula a more useful part of the game.

Edit: Spelling error, thanks Narf for pointing it out. I owe you one.

[ January 28, 2004, 07:06: Message edited by: Atrocities ]

[Karibu]

Mining black holes is propably Last thing mankind ever learns to do, if ever. As we know, black holes are virtually everLasting (but not practically. There are few events caused by laws of quantum mechanics, which result that even black holes will lose mass and vanish in time and I am not talking about millions of years, but 10^90 years) and nothing can escape from there.

However, even if we could extract some material from a singularity, I doubt it could be of any use. Basically it is assumed that it consists of only protons and neutrons which would combine combounds with the nearby matter (atoms, electrons, neutrons, other protons) at the very same moment they would be taken off from the high gravity area. However this is interesting theoretical discussion

[ January 28, 2004, 07:50: Message edited by: Karibu ]

[Suicide Junkie]

Nebula's are basically gasses being held in place by a gravitational force or other. These nebula can be pretty much any gas combination. So to turn this toward an SEIV topic, would it be possible to make a component that could use the inherent gasses of a nebula and convert them into energy for a ship or say stationary Starbase where a Q-reactor was not present?

Also known as ramscoops.

The element mix you'll find is essentially pure hydrogen with a tad of helium mixed in. Fly through at high speed, and scoop up those 10,000 molecules per cm^3
You'll have to sweep 3x10^17 cubic meters before you've got 1 gram of hydrogen though, so you need a big scoop.

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And the densities of nebulae are so very low, only "none" races could consider it breathable.
Plus, there are no convenient ways to move around, since the material is so very thin, and there aren't even any stars around to sail by.

Black holes are a bad idea to mine for matter.
Jupiter would be uneconomical to pull material up from.
Stars are much worse, and hotter too. Solar wind is too thin to bother with.
Neutron stars, well your digging equipment would be compacted into neutronium and join the star, and the gravity is much worse.
Black holes are insanely bad.

They do evaporate, though, and emit radiation like a blackbody. As they get smaller, their effective temperature goes up and they emit more, and shrink faster until boom.

In the Last second of its existence, according to theory IIRC, it will lose 1000 tons of mass as energy. Enough to sterilize the entire solar system from anywhere nearby.

Any decent sized hole has an effective temperature lower than the surrounding universe, and will just pull in photons and stray atoms to grow.
Eventually, as space expands, the surroundings will approach emptyness, and the huge hole will begin to evaporate.

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The scale of time you are talking about is many millions of years.
If the race is waiting for nebulae to form randomly, they'd be an incredibly ancient race.

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PS:
Fun trumps all! If it would be fun to play, go ahead and do it!