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-   -   can some one explain space to me..... (http://www.bushtarion.com/forums/showthread.php?t=6251)

willymchilybily 12-12-2012 06:11 PM

can some one explain space to me.....
 
i know there's some clever people in Bushtarion, I'm hoping you still hang around. i have something that is bugging me.

in my knowledge of chemistry, stuff boils at lower temperatures in a vacuum. example vacuum distillation of heat sensitive materials.

so now imagine I'm on a space ship, naked, and I'm jettisoned into space. straight away all the air around me is removed into the vacuuum of space along with myself, even the air in my lungs etc.

now the water on my eyeballs, and in my breath and mouth should in theory in a complete vacuum, evaporate, and this will provide some cooling instantly. but other than this i shouldn't lose heat too quickly as there is no atoms/mass around me to remove the heat. all i can do is radiate heat.... so eventually i cool down. but i should not instantly freeze, even when dead ill have some respiratory and digestion going on, even the fat cells decomposing once i die? correct? i should die long before i fully freeze?

another thing is why does ice form on the space ship hull/windows (in the movies) in a complete vacuum. it can cool down, by radiation, until there is no heat left in it. depending on distance from the radiation from the sun. So how does the ice then attach to the space ship going from a vapor molecule something with a relatively small size to ice on the windows, as a solid would require a collection of water molecules to be able to form in the first place? is it that it remelts at low temperature in the vacuum of space. attach to the spaceship as the space ship collides with it then re-freeze as it radiates the tiny amount of heat. whereby the collision and surface of the shuttle has enough heat to melt it in the first place? or enough mass to allow the very few vapour molecules to collect on it? and where do the molecules come from, id assume they would be drawn to something with mass, but not just hang in limbo in space for very long? I'm struggling conceptually to understand it. so any input is welcome. or even a website link....probably should have googled it first tbh. but meh.

have at it

Max 12-12-2012 09:03 PM

Hi willy!

In answer to question 1 - you would die well before freezing. The vacuum of space has an incredibly low pressure, which means in fact your blood would BOIL (not freeze) much quicker than anything else. Ever seen an experiment with a vacuum flask and a cup of red dyed water inside? The result isn't pretty :P

In answer to question 2 - spacecraft don't actually freeze in reality. It may happen in the movies, but as you rightly point out you'd need a lot of water vapour in space, which just doesn't exist. The spacecraft I am currently working on gets as cold as -150 out on the boom in the Sun's shadow, and it sure as hell doesn't freeze :P The metal just gets very cold, that's all.

pistol 12-12-2012 10:59 PM

Quote:

Originally Posted by Max (Post 88000)
Hi willy!

The spacecraft I am currently working on

Max your such a badass!

Twigley 12-12-2012 11:16 PM

Quote:

Originally Posted by pistol (Post 88002)
Quote:

Originally Posted by Max (Post 88000)
Hi willy!

The spacecraft I am currently working on

Max your such a badass!


Benneh 12-12-2012 11:40 PM

Quote:

People assume that time is a strict progression of cause to effect, but actually, from non linear non subjective point, its more like a big ball of wibbly, wobbly, timey, wimey... stuff

timtadams 13-12-2012 06:46 AM

Quote:

Originally Posted by Twigley (Post 88003)
Quote:

Originally Posted by pistol (Post 88002)
Quote:

Originally Posted by Max (Post 88000)
Hi willy!

The spacecraft I am currently working on

Max your such a badass!



No-Dachi 13-12-2012 09:05 AM

A follow up question; how can there be temperatur in a vaccum? If there's no mass, there should be nothing to heat, and it should be zero Kelvin?

antisback 13-12-2012 10:26 AM

Quote:

Originally Posted by No-Dachi (Post 88010)
A follow up question; how can there be temperatur in a vaccum? If there's no mass, there should be nothing to heat, and it should be zero Kelvin?

Photons my friend, also there is mass - no vacuum is truely massless. Even if you could suck all the mass out you'd still get virtual particles.

Max 13-12-2012 10:47 AM

antisback is spot on, a vacuum is never TRULY a vacuum.

There's always stuff going on in terms of particle-antiparticle pairs popping in and out of existence all the time.

Physicists describe the result as there being a "Quantum Zero-Point Energy" attributed to empty space, such that even what we would consider a perfect vacuum has some residual energy associated with it, giving the potential for these particles.

But in space there are actually plenty of particles zipping about to and fro (they are just very sparse, about 5 in every cubic centimeter I think), so it's not a real vacuum anyway. You are correct to assert that "temperature" is a property of the particles though.

timtadams 13-12-2012 12:29 PM

I thought zero point energy was the theoretical, and inaccessible, energy minimum of any molecule/lattice. Because temperature is a bulk property describing the distribution of particles in various vibrational, rotational and translational energies (depending on the phase). Higher temperatures = more molecules/atoms with higher vibrational/rotational/translational energies. i.e. vibrating with higher amplitude or moving faster.

At zero Kelvin (absolute zero) then the molecules must have zero rotational/translational energy. If considering an atomic gas like argon, then it will freeze into a solid crystal with zero translational and rotational motion. However, even at absolute zero the atoms in the crystal will still be vibrating with a certain energy. At zero Kelvin all atoms are vibrating in the ground state. This vibration has a certain energy associated with it. There is also a theoretical energy minimum associated with all the atoms being perfectly still. I thought this is called the zero point energy. This state is purely theoretical and cannot be accessed. Something to do with Herzberg uncertainty principle??

I only did chemistry, not physics, so forgive me if I got it wrong. I would be very happy to get a better understanding of it.

Also, regarding freezing on space ships, any body above zero Kelvin will radiate energy. The energy distribution of photons radiated is related to temperature. Often approximated as black body radiation. The transition from one vibrational state to a lower vibrational state can be associated with the emission of a photon of equal energy. And this is the source of radiation. Higher temperature of body = higher occupancy of higher energy states and thus emission of higher energy photos during transition to ground state.

So considering a space ship with the cabin at something like 23 degrees. The air in the cabin would contain water vapour. If the ship was in a vacuum it would be losing heat by radiation add we already know. As Max said, metals get very cold. Now imagine any surface on the inside of the cabin is really cold due to the radiation of heat. A water molecule in the cabin at 23 degrees will have translational, rotational and vibrational energy. If it collides with the cold surface, that energy can be transferred to the material quite easily. And the molecule now has no translational energy and is stuck to the cold surface by van der Waals forces. When lots of water molecules collide with the surface you get a build up of water. This is the reason your windscreen fogs up when it's cold. And if it is very cold and there is enough water, you will get a build up of ice. However the cabin of any space craft would be insulated, and the windows double/triple glazed so that there wouldn't be any very cold surfaces inside the cabin for ice to form. Is that right Max?

Max 13-12-2012 02:58 PM

Yeah you've it pretty much spot on timtadams - the only thing you need to know is that the "vacuum energy" is the "zero point energy" of all fields in space, rather than just a property of a physical lattice. The ground state of all fields.

It's inaccessable, but I'm pretty sure it's responsible for quantum particle-antiparticle fluctuations as well. Due to Heisenberg's uncertainty principle, particles can "borrow" some energy for a short period of time, so long as they give it back pronto :P This mechanism is responsible for the Hawking radiation you get coming off black holes.

As for the INSIDE of a cabin on a MANNED spacecraft - I don't see any reason why it couldn't freeze over. In the same way you get condensation on the inside of the car. If the outer metal is cold enough the water vapour inside will gladly condense and freeze, since there is plenty of water vapour inside. Just not outside ;)

antisback 13-12-2012 05:53 PM

If the inner windows/walls of your space craft are cold enough to freeze water vapour, you're in for a bad time.

Remind me not to get inside of any Max designed spacecraft :P

Max 13-12-2012 08:11 PM

Quote:

Originally Posted by antisback (Post 88024)
If the inner windows/walls of your space craft are cold enough to freeze water vapour, you're in for a bad time.

Remind me not to get inside of any Max designed spacecraft :P

I'm incredibly anti-manned spaceflight so you are safe for now - GO ROBOTICS!

Alvestein 16-12-2012 12:01 PM

Quote:

Originally Posted by timtadams (Post 88007)
Quote:

Originally Posted by Twigley (Post 88003)
Quote:

Originally Posted by pistol (Post 88002)
Quote:

Originally Posted by Max (Post 88000)
Hi willy!

The spacecraft I am currently working on

Max you're such a badass!



It's been awhile since anyone has quoted this so I thought I'd do it just to make sure no one forgets.

Hobbezak 17-12-2012 07:29 PM

stfu hiuey!


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