# 0 K

#### curioucity

##### Unbelievable and odd
Registered Senior Member
Here is my opinion on things at 0 K

The possibility of matter growing as cold as 0 K lies between two 'values':

1) 0 K is unreachable-> All matters always stay in motion
2) the temperature may reach 0 K, but cannot stay at 0 K-> 0 K implies no energy, at the instant the electron stops moving, the kinetic energy is 0, but the gravitational and electrical forces causes the electron to move again, and then it fuses with proton to release energy.
Personally, probability 1) is the most possible.

1 is right but not for the reason you gave.

At the subatomic level, the definition of motion can sometimes be pretty motionless. Quantum mechanics basically tells us that bodies in a region of potential cannot exist with zero energy and the third law of thermodynamics tells us that 0 K is physically unattainable.

I take that thanks...
I forgot to use the word energy instead.... actually I was only considering the kinetic when writing the 1st statement....

Just for the record, what temperature where-abouts are vaccuums, exactly? I know this will involve a long and complicated answer involving "there is no temperature because there are no molecules to vibrate" - but of course I don't referr to a perfect vaccuum.

disposable88:

If you're not referring to a perfect vacuum, then the temperature is the temperature of whatever is in there.

A perfect vacuum has no temperature. The concept has no meaning in that situation.

Originally posted by ryans

the third law of thermodynamics tells us that 0 K is physically unattainable.

It would take an infinite amount of energy to attain 0 K.

If there were nothing in our universe it would have a temperature of 0 K, which, as James R has said, is not really a temperature anyway! It is a fundamental constant of our universe.

Originally posted by curioucity

0 K implies no energy.

At 0K, a system will be at the lowest energy, that doesn't neceesarily say that this energy equal 0.

At zero Kelvin,a gas composed of fermions (like the electrons for example), will have all its levels filled with only one electron for each state (the state includes the electron spin). In principle, the electron with the highest energy can have a very high energy.

there are two things to consider here. the laws of thermodynamics dictate that you can never get a system to 0K, even if its lowest state has 0 energy. so even a system of classical particles can never be 0K.

QM also tells us that no system has 0 energy in its lowest state. this is unrelated.

Re: Re: 0 K

Originally posted by 1100f
At 0K, a system will be at the lowest energy, that doesn't neceesarily say that this energy equal 0.
This is true. Even at absolute zero there is still some molecular motion. The energy that remains when a substance is at absolute zero is the zero-point energy.

sorry, but I'm quite a beginner...

Can you explain what fermion is? I have seen this word several times but yet I cannot figure out exactly what that is....
Oh and about the history of 0K theory 'invention'...
I once read this article (I forgot most of the part), saying that some scientist suggested the value of 0K to be -273.16 deg Celcius when they drew the linear graphic of V/T of gas, and when they virtually drew the line so that it hit the T axis (thus v=0), the coordinate of that point of intersection appeared to be -(273.16 deg Celcius, 0 m cubic)....
I want you opinion (and correction, since I may have accidentally altered somthing) on this, thanks.

Re: sorry, but I'm quite a beginner...

curioucity:

<i>Can you explain what fermion is? I have seen this word several times but yet I cannot figure out exactly what that is....</i>

All fundamental particles in the universe are either bosons or fermions. Fermions are particles with spin 1/2, 3/2, 5/2 etc. Bosons have spin 0,1,2,3 etc.

<i>I once read this article (I forgot most of the part), saying that some scientist suggested the value of 0K to be -273.16 deg Celcius when they drew the linear graphic of V/T of gas, and when they virtually drew the line so that it hit the T axis (thus v=0), the coordinate of that point of intersection appeared to be -(273.16 deg Celcius, 0 m cubic)....</i>

Yes. The absolute temperature (Kelvin) scale is defined in terms of ideal gas parameters. On that scale 0K = -273.15 Celcius.