# 0 degrees Kelvin

## Main Question or Discussion Point

1)I am very interested to know about studies being done into the uses of atoms at 0 degrees Kelvin (I understand this as the temperature at which atoms cease to oscillate?) Apparently this has possible uses as nano-computers whereby a normal object, such as a coin can house massive memory. This is what I have heard from some of my collegues in physics. This is very interesting. If you know anything about the mechanics of extremely low temperatures on atoms, please write.
2)The average temperature of the universe is around 3 or 4 degrees Kelvin. Is this true? How can this be? Please help.

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1) Atoms never cease to oscillate at 0 K , they still "jiggle" around.The reason for this is that if atoms cease to oscillate at 0K , then we can easily depict its position which is not possible as per Uncertainity Principle.Although this "Jiggle" is so little , that it almost respects the Heisenberg Principle.

2) Never heard of the information, Maybe abstract knowledge.

BenGoodchild
The average temperature is about 2.725degrees Kelvin and is found using using Planck's Black Body Radiation Law.

Ryan Lucas said:
2)The average temperature of the universe is around 3 or 4 degrees Kelvin. Is this true? How can this be? Please help.
don't forget most of the universe is completely empty, and where there is nothing, there is no temperature, the mode temperature is therefore 0K.

also, Kelvin is not measured in Degrees

It's impossible to reach absolute zero (supposedly, but I have my doubts - see http://www.chronon.org/articles/absolute_zero.html). Quantum computers promise a great improvement on normal computers, and some types of quantum computers devices at low temperatures but not at absolute zero. See http://www.qubit.org/ for more information on quantum computers. (Again I have doubts about the accepted view - see http://www.chronon.org/articles/quantum_computers.html)

The temperature of the universe is that of the cosmological microwave background radiation, which was emitted a few hundred thousand years after the big bang, and we see highly redshifted. Essentially we are seeing back to a much earlier stage of the universe. See http://www.astro.ucla.edu/~wright/cosmo_01.htm

don't forget most of the universe is completely empty, and where there is nothing, there is no temperature, the mode temperature is therefore 0K.
hexhunter, you have got me roaring like an angry tiger!!! grrrrrr, misinformation.

Space is not empty, it is full of thermal radiation at 2.75 kelvins!

This radiation is actually the afterglow from the big bang, and it fills every nook and cranny of the entire universe! Including regions that are empty of matter (actually not empty, about 2 protons per cubic meter).

This radiation is in the microwave frequency spectrum, so it is called the Cosmic Microwave Backround CMB. The CMB is about as well established as anything can be in science, so please read a book.

SpaceTiger
Staff Emeritus
Gold Member
2)The average temperature of the universe is around 3 or 4 degrees Kelvin. Is this true? How can this be? Please help.
It all depends on what you're taking the temperature of. Most of the radiation in the universe is in the CMB, which has a temperature of 2.73 K. Most of the matter in the universe is in the form of dark matter, for which we can only say that it's non-relativistic (leaving the temperature very uncertain). Finally, most of the baryonic matter (the stuff we're made of), is in diffuse gas at extremely high temperatures (~106 K).

The point is that the universe is not in thermodynamic equilibrium, so giving it a single temperature doesn't make sense.

Danger
Gold Member
SpaceTiger said:
Finally, most of the baryonic matter (the stuff we're made of), is in diffuse gas at extremely high temperatures (~106 K).
Could you elaborate upon this, please. I've always thought that it would be cold because of being diffuse (heat of compression and whatnot). Is the measurement taken from how fast the atoms are moving, regardless of how many collisions they undergo?

SpaceTiger
Staff Emeritus
Gold Member
Danger said:
Could you elaborate upon this, please. I've always thought that it would be cold because of being diffuse (heat of compression and whatnot). Is the measurement taken from how fast the atoms are moving, regardless of how many collisions they undergo?
Temperature is basically related to the average kinetic energy of the particles in the gas. Keeping this in mind, imagine that you have some process that is producing energy and dumping it into space. This could be a supernova blast wave, light from a bright star, or a shock wave from the collision of two galaxies. If this process dumps the same total energy into the gas, which will have a higher energy per particle, a high-density gas or a low-density gas?

Danger
Gold Member
SpaceTiger said:
which will have a higher energy per particle, a high-density gas or a low-density gas?
Okay, got it. Thanks, Tiger. I think that my confusion was in considering the gas as a whole rather than on an individual atom basis.

Space is not empty, it is full of thermal radiation at 2.75 kelvins!
I think what he meant to say is that space is virtually empty of matter--light (and radiation) has no matter, therefore "nothing" could be considered to be there.

I understand where you're coming from, and I agree, but on the flip side, it's also true that nothing with matter exists between stars, planets, etc.