when the temperature of matter increases the particles

So not having the air around should make your arm feel a bit warmer than it would otherwise. If there were air in the room, there would also be some convective cooling of your arm by the air. So there's a net flow of radiant heat out from your arm to the room. Your arm is at ~37☌ internally, somewhat cooler on the surface but still well above 22☌. Say you stick your arm into a vacuum room at some normal temperature, say 22☌. I think it wouldn't feel very hot or cold. (published on ) Follow-Up #1: vacuum temperature By the way, the third law of thermodynamics says nothing can ever get to zero temperature, so by that definition there wouldn't be any vacuums.

If you want, though, you could choose to only call that a vacuum if the temperature is zero. are pumped out, yes it still has a temperature of electromagnetic radiation. If you mean what's left when all the atoms etc. So the answer really depends on what you mean by vacuum. There's little you can do about the neutrinos and dark matter - they penetrate ordinary matter, but also don't really interact with it so to a good approximation you can neglect them. You have to also shield it from outside sources of energy. Cooling the walls down to as close to absolute zero as you can get (and the limit here is that photons of energies that would be radiated by a wall of a cold temperature would have wavelengths longer than the size of the can - that'll let you freeze out all of the photons) will give you a vacuum. There may be other stuff, like the neutrinos, for example, which are not in thermal equilibrium with the 3K radiation because they don't interact with it, and so space may have two or more 'temperatures'.īut we said a vacuum is a region of space with nothing in it, and that means those photons have to go. In fact, even the deepest of deep space (outside the galaxy, for example), is in a radiation bath of temperature 3K, left over from the Big Bang. This soup of photons will be in thermal equilibrium with the walls, and therefore will have a defined 'temperature'. If you manage to pump all the air out of a steel can, for example, you will have a vacuum in there, but there will be photons constantly radiated off of the walls and re-absorbed by them. It's probably also filled with dark matter which doesn't interact with other stuff (except gravitationally, and possibly only through the feeble weak interaction), as well as neutrinos. Space beyond the Earth's atmosphere isn't a bad approximation to a vacuum, but it is filled with solar wind particles, light from the sun, cosmic rays and cosmic microwave background radiation. We don't know of any examples of a perfect vacuum, but know some bits of space that get pretty close. This tendency of diffusion is merely a matter of odds, as particles are more likely to move from higher concentration to lower concentration than the opposite simply because there are more particles in high concentration areas to move elsewhere.Well, our idea of a vacuum is a bit of space with nothing in it. There is no force in normal diffusion that makes any particular particle more likely to move into an area of lower concentration.

While writings about diffusion often describe the process as the tendency of particles to move from areas of higher concentration to areas of lower concentration, this is somewhat misleading. The concentration difference is also another important factor, with greater differences resulting in faster diffusion. A larger particle requires more energy to move, and therefore at any given temperature, larger particles tend to diffuse slower than smaller ones. Another aspect of diffusion rate, still related to temperature, is the size of the particles involved. Temperature is an important factor in determining the rate of diffusion, but it is only one of several.

When the temperature of matter increases the particles