# Thread: Absolute Zero and Volume

1. I know that the current known laws of physics prevent a temperature at absolute zero from being reached; however, theoretically, what happens to the volume of an object at absolute zero?

According to the equation PV = nRT

(Pressure * Volume) = (amount * a constant * temperature)

when the temperature is 0, either volume or pressure must also be zero.

Any ideas?

2.

3. If I had to take a big guess, from the way I understand things, I think pressure would be zero at 0 temperature.

4. I think those equations are for ideal gasses. Maybe another more real-world equation exists? Question: Does "temprature" only refer to the chaotic movement of the atom/molecule as a whole or does it include electron movement as well? If not, the volume should drop some, but the effective volume of each atom/molecule should still be more than the actual physical width of each. That is outside pressure, isn't it? That should stay constant. IMO. Good question

5. The reason we can't get to absolute zero is because time stops for that object at zero point and requires a lot of energy to keep it that way, if not an infinite amount.

6. Originally Posted by svwillmer
The reason we can't get to absolute zero is because time stops for that object at zero point and requires a lot of energy to keep it that way, if not an infinite amount.
Time would not stop. People keep trying to equate time with motion and while related they are not equivalent. Even at absolute zero you'd still have QM effects/zero-point energy anyway.

7. Originally Posted by Nima Rahnemoon
According to the equation PV = nRT...
I'll give you the simple and obvious answer.

The ideal gas equation applies only to gases. As you enter cryogenic temperatures, all known gases will freeze. They are now solid and the above equation no longer applies.

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8. At risk of sounding overly pedantic to SteveF's statement to ''As you enter cryogenic temperatures, all known gases will freeze.'' I thought it should be worthy adding that they freeze to *liquids* and not solids what day to day thinking might suggest.

It doesnt make any difference just a bit of worthless knowledge!

Barry

9. Originally Posted by Barry Flannery
At risk of sounding overly pedantic to SteveF's statement to ''As you enter cryogenic temperatures, all known gases will freeze.'' I thought it should be worthy adding that they freeze to *liquids* and not solids what day to day thinking might suggest.

It doesnt make any difference just a bit of worthless knowledge!

Barry
Hmm. Dry ice is solid carbon dioxide.

10. Harold,

Good point but I was mainly referring the noble ones.

11. Originally Posted by Nima Rahnemoon
(Pressure * Volume) = (amount * a constant * temperature)

when temperature is 0, either volume or pressure must also be zero.

Any ideas?