0 Kelvin ppl!!

[Liiia]

Sooo a friend of mine had a couple questions in mind, if you guys have any possible answers, please do share, give us your thoughts

1- Can there be energy in 0 Kelvin?
2- Can 0 Kelvin exist in the universe?

Answers appreciated in advance

[Fuzzwood]

1) You will still have the vibrational zero-point energy.

2) There is always some form of EM radiation or even gravity wells in the known universe. So no.

 

I expect and invite someone more educated in physics to beat me around the head now.

[timo]

There are three main examples of energy at 0 K: 1) Often you are free to chose the zero-level of energy yourself, which obviously makes it possible. 2) Mass is often considered a form of energy and does not vanish at zero temperature. 3) most relevant to the question: Many systems will have kinetic energy at zero temperature, e.g. a set of many independent atoms (the atoms do not move, but the electrons orbiting the nucleus have a certain amount of kinetic energy).

 

Your 2nd part of the question is a bit tricky, going into some subtleties of thermodynamics. The simple answers would be a mix of yes and no: Thermodynamics states that zero Kelvin cannot be reached by thermodynamics processes. But apart from that there is nothing too special about zero temperature, at least in theoretical models. The mainstream answer would probably be "no" due to the well-known statement about thermodynamic processes (combined with an incomplete understanding of the concept of the thermodynamic limit). The formally more correct -but completely useless- statement would be that thermodynamics cannot exist.

[MigL]

Even in the complete absence of any matter or radiation, we still have the quantum mechanical process responsible for vacuum fluctuations/virtual particles, i.e. energy borrowed from the vacuum. The HUP makes this impossible to eliminate.

[Wso]

Even if we assume for a moment that it is possible to have something that has no energy of any kind, how would you reach this state? Energy flows from high to low so reaching absolute zero would (please correct me if I'm wrong here) require something below absolute zero, or in other words, something that has a negative amount of energy. You can't get negative energy so this means that reaching that 0 energy level is not possible.

Good question. I hope that this helps you and your friend.

Edited November 14, 2014 by Wso

[AndresKiani]

This is much more fundamental.

 

The principle of entropy is completely against 0K, if you think about it.. in order to extract that last bit of energy away from a particle you have to have another particle with less than 0K to absorb that energy.

 

Since there is already no such thing as 0K, this nearly impossible (I say nearly cause our knowledge is dependent on our technology and understanding of this universe).

Also remember E = mc^2? In the lamest terms, this means energy and mass are interconvertable. If you lose complete energy, matter will break down, I imagine that you won't have matter in general since the elementary particles of matter are derived from energy.

[studiot]

 

The principle of entropy is completely against 0K, if you think about it.. in order to extract that last bit of energy away from a particle you have to have another particle with less than 0K to absorb that energy.

 

Have a care with this argument.

 

Entropy 'extracted' is defined as the heat extracted, (not the energy) divided by the absolute temperature of that extraction so extraction at 0^o leads to a division by zero singularity.

[swansont]

Also remember E = mc^2? In the lamest terms, this means energy and mass are interconvertable. If you lose complete energy, matter will break down, I imagine that you won't have matter in general since the elementary particles of matter are derived from energy.

Temperature is related to kinetic energy, not mass energy. 0K means no center-of-mass motion for the constituent particles of the ensemble. kT varies with mv², not mc²

 

[AndresKiani]

 

Have a care with this argument.

 

Entropy 'extracted' is defined as the heat extracted, (not the energy) divided by the absolute temperature of that extraction so extraction at 0^o leads to a division by zero singularity.

 

Well what I mean is that inorder to extract that last bit of energy wouldn't you need something with less kinetic energy to absorb it, thus making it nearly impossible to reach 0 K? I referred to entropy because in our universe.. we don't see objects with less energy favorably losing more and more energy around systems of higher energy.

 

Temperature is related to kinetic energy, not mass energy. 0K means no center-of-mass motion for the constituent particles of the ensemble. kT varies with mv², not mc²

 

 

I understand 0 K means no kinetic energy, no kinetic energy means the particle has no center of mass motion, trust me. This was actually one of my professors arguments when a student asked him the very same question last summer he said that if we take a look at mass and energy, referring to 0 K kinetic energy, than it would be impossible to reach it because you would essential need eliminate the mass of the object for it to successfully reach 0 K.

[swansont]

 

I understand 0 K means no kinetic energy, no kinetic energy means the particle has no center of mass motion, trust me. This was actually one of my professors arguments when a student asked him the very same question last summer he said that if we take a look at mass and energy, referring to 0 K kinetic energy, than it would be impossible to reach it because you would essential need eliminate the mass of the object for it to successfully reach 0 K.

 

I don't there's a sound physics argument behind that, nor does that extrapolate to matter "breaking down". I think that it's an issue of needing m to vanish (mathematically). But a zero mass particle moves at c, and has energy and momentum.

[studiot]

This is a prime example of where hand waving explanations break down in the face of hard facts.

Actually the entropy at 0^oK need not be zero.

 

Atkins give the value of 0.21 JK^-1 per gram for solid carbon monoxide, both experimentally measured and theoretically derived.

 

The mechanism is due to random variations of orientation of the molecules.

[AndresKiani]

 

I don't there's a sound physics argument behind that, nor does that extrapolate to matter "breaking down". I think that it's an issue of needing m to vanish (mathematically). But a zero mass particle moves at c, and has energy and momentum.

 

Please fully explain your point because your just throwing around obvious facts. What is your point? I understand what you mean by the mathematics however.

 

My main point is this, if you think about the question of whether or not we can reach the state of absolute zero or not? I believe that besides the fact that the elementary particles of matter perhaps experience quantum fluctuations in which their motion never comes to complete halt in which we could measure. Thus perhaps there will always be remaining kinetic energy.

 

Though my initial explanation was much more basic than that. Without the notion of quantum mechanics, absolute zero to me still seems impossible due to basic and pure thermodynamical postulations in which energy always flows from high energetic systems to low energetic systems. Thus, inorder to extract that last bit of energy one must utilize an instance of lower energy than 0K to effectively extract that energy and thus makes it impossible in based upon our current universal laws.

[swansont]

 

Please fully explain your point because your just throwing around obvious facts. What is your point? I understand what you mean by the mathematics however.

 

The point was that the bit about "matter breaking down" is wrong. Now you claim you knew the answer all along. What's the point of that? (That's rhetorical; something to ponder. I don't really care)

[AndresKiani]

 

The point was that the bit about "matter breaking down" is wrong. Now you claim you knew the answer all along. What's the point of that? (That's rhetorical; something to ponder. I don't really care)

 

With I due respect..so far you have managed to give a us a description of kinetic energy, thank you I applaud you. In which I clearly stated was inspired by an answer given to us by my professor last summer when a student asked a similar question.

 

You didn't not once comment on the thermodynamics that I was discussing, and you completed avoided the quantum fluctuation aspect of it as well. Are those sufficient answers to this problem of 0K or am I missing something else? I want to hear your whole point on the matter not just the fact that I was wrong about the thermal energy = breaking down of matter which sounds absurd to me know that you point it out.

Edited December 14, 2014 by AndresKiani