This discussion centers on the implications of an atom reaching absolute zero energy and the resulting behavior of the atom in an isolated environment. Participants agree that as an atom approaches absolute zero, its kinetic energy (KE) approaches zero, leading to a smeared-out state due to the Heisenberg Uncertainty Principle (HUP). The conversation also touches on the philosophical implications of atomic stability and the nature of quantum mechanics (QM) in relation to single particles versus multiple particles in the universe.
PREREQUISITESPhysicists, students of quantum mechanics, and anyone interested in the fundamental principles of atomic behavior and thermodynamics.
Mu naught said:If you placed an atom in an empty universe that was completely dark and cold, would it eventually radiate away all its energy until it had zero KE?If so, what would happen to an atom with zero energy?
Unstable is another way of saying they're not the permanent solid little particles we're used to thinking of them as.Mu naught said:In this sense, are atoms inherently unstable systems?
DaveC426913 said:KE is a relative concept. A single atom with no motion relative to anything else has no KE.
However, I think you've touched on something profound. An isolated atom would have no constraints on its position or velocity and thus would cease to have a discrete value for either. The atom would smear out across space, potentially without limit. Interestingly, this is the same thing that happens to atoms cooled to (almost) absolute zero (Bose-Einstein condensate).
Unstable is another way of saying they're not the permanent solid little particles we're used to thinking of them as.
When an atom approaches absolute zero, its velocity approaches zero. As per HUP, if its velocity is well-defined, its position becomes poorly-defined. Atoms near 0K really do smear out.Rebound said:I was going to say that I presumed when you said it would cease to have a discrete value, that it was because with no outside observer it would be equally likely to appear at any point in the universe. The bold text, however, indicates to me that this is incorrect. Please explain.
DaveC426913 said:When an atom approaches absolute zero, its velocity approaches zero. As per HUP, if its velocity is well-defined, its position becomes poorly-defined. Atoms near 0K really do smear out.
When you say "equally likely to appear at any point in the universe", that is the same thing as saying it is essentially at any point in the universe (i.e. when you go to observe it, it's there). i.e. it has smeared out across the universe.
They are two sides of the same coin.
DaveC426913 said:When an atom approaches absolute zero, its velocity approaches zero. As per HUP, if its velocity is well-defined, its position becomes poorly-defined. Atoms near 0K really do smear out.
When you say "equally likely to appear at any point in the universe", that is the same thing as saying it is essentially at any point in the universe (i.e. when you go to observe it, it's there). i.e. it has smeared out across the universe.
They are two sides of the same coin.
Mu naught said:Even though this is just a "thought experiment" in reality, eventually the entire universe will cool off will it not?
DaveC426913 said:b] the heat will be evenly distributed.
Sakha said:If we say that universe is fixed size, this would require some kind of mirror or something at the 'edge' of the Universe?
Sakha said:If we say that universe is fixed size, this would require some kind of mirror or something at the 'edge' of the Universe?
DaveC426913 said:An isolated atom would have no constraints on its position or velocity and thus would cease to have a discrete value for either. The atom would smear out across space, potentially without limit. Interestingly, this is the same thing that happens to atoms cooled to (almost) absolute zero (Bose-Einstein condensate).
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Can you explain this? Why would the atom smear out across space?
No I can't. That's just the way QM is.Drakkith said:Can you explain this? Why would the atom smear out across space?
DaveC426913 said:No I can't. That's just the way QM is.
DaveC426913 said:No I can't. That's just the way QM is.
jensel said:I cannot agree reading this thread. QM is a theory, nothing more. It is has been tested under the condition that we have a universe with many particles and energy. To follow that the eigenstates of such a single atom allow to be expanded in space in infinity would imply that QM is founded on an interaction in the universe with the interaction of other materia.
QM is more or less a theory of single particles, interacting if at all in a simple case. It needs linearity from the beginning.
It is not okay to talk about a universe with one atom. You should not forget that we expect the universe to be more or less 4 dimensional, where we have those dimensions because we have more than one single atom.
Jens
Rebound said:You have no sense of fun.
jensel said:This is not fair. You don't know me in person and I am not an native english speaker. This forum is about physics and I try to answer in way which is only about the subject. It has nothing to do with me in person.