Absolute Zero - No Entropy -Quantum Jiggles?

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Discussion Overview

The discussion revolves around the concept of absolute zero, specifically addressing the implications for entropy and quantum motion at this temperature. Participants explore the nature of "quantum jitters," zero-point energy, and the Heisenberg uncertainty principle in relation to absolute zero.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that at absolute zero, there is no entropy, questioning whether "quantum jitters" still occur.
  • Others seek clarification on what is meant by "quantum jitters," with suggestions that it may refer to the cessation of all motion, which could conflict with quantum principles.
  • One participant states that objects at absolute zero still possess zero-point energy, implying that motion does not completely cease.
  • Another participant argues that absolute zero cannot be achieved due to the Heisenberg uncertainty principle, which suggests that atomic motion cannot be zero.
  • A later reply introduces the de Broglie-Bohm interpretation, suggesting that particles can be stationary at absolute zero without violating the uncertainty principle, as it applies to ensembles rather than individual systems.
  • Some participants challenge the notion that all motion ceases at absolute zero, referencing mainstream quantum mechanics that indicates motion persists due to zero-point energy.
  • Discussion includes references to specific texts and concepts, such as the quantum harmonic oscillator and the behavior of noble gases as they approach absolute zero, highlighting the complexities of specific heat and energy levels.

Areas of Agreement / Disagreement

Participants express differing views on the nature of motion at absolute zero, with no consensus reached on whether absolute zero can be achieved or if motion ceases entirely at that temperature.

Contextual Notes

Limitations include varying interpretations of quantum mechanics, dependence on specific theoretical frameworks, and unresolved mathematical implications regarding energy levels and motion at absolute zero.

Quantum Bum
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When something is frozen fully, and the temperature is absolute zero -there is no entropy - but does that mean the "quantum jitters" are not occurring?
 
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What are quantum jitters exactly?
 
Stuff at absolute zero still have zero-point energy, if that's what you're asking.
 
Drakkith said:
What are quantum jitters exactly?

I'd assume he or she means that all motion ceases, down to quantum level, violating the HUP, and maybe a host of other quantum phenomenon that are often lumped together. Probably a good explanation of why you never CAN get to AZ.
 
What that means is that you cannot have something at "absolute zero". Absolute zero means no motion at all. As long as you sure the object whose temperature you are lowering is in the same building with you Heisenberg uncertainty means the speed of the atoms making up the object cannot be 0.
 
HallsofIvy said:
What that means is that you cannot have something at "absolute zero". Absolute zero means no motion at all. As long as you sure the object whose temperature you are lowering is in the same building with you Heisenberg uncertainty means the speed of the atoms making up the object cannot be 0.

Unfortunately, that statement is interpretation-dependent. In the de Broglie-Bohm interpretation (experimentally equivalent to orthodox QM), the zero-point energy is a 'quantum potential energy' (source: Holland's deBB textbook 'The Quantum Theory of Motion'). For a zero-angular momentum stationary state at absolute zero, the particles really do come to a dead stop, with zero kinetic energy. This doesn't violate the Heisenberg uncertainty principle because that principle only refers to ensembles of identically prepared systems. Over the ensemble, there is a distribution of positions in space in which the particles come to a dead stop which obeys the HUP, but for any individual system they are nevertheless stationary.
 
HallsofIvy said:
What that means is that you cannot have something at "absolute zero". Absolute zero means no motion at all. As long as you sure the object whose temperature you are lowering is in the same building with you Heisenberg uncertainty means the speed of the atoms making up the object cannot be 0.

This is -as Camboy has already mentioned- not quite correct. According to what I would consider to be "mainstream" QM things DO move even at absolute zero.
See e.g. Gardiner's book on Quantum Noise (as far as I remember there is even a calculation in there showing how fast an electron would move due to ZPE random-walk motion, a very small but non-zero number)
 
f95toli said:
This is -as Camboy has already mentioned- not quite correct. According to what I would consider to be "mainstream" QM things DO move even at absolute zero.
See e.g. Gardiner's book on Quantum Noise (as far as I remember there is even a calculation in there showing how fast an electron would move due to ZPE random-walk motion, a very small but non-zero number)

So quantum zero-point motion -vibrations, or are you saying more then this?
 
Quantum Bum said:
So quantum zero-point motion -vibrations, or are you saying more then this?

In quantum harmonic oscillator, the LOWEST possible level has an energy of 1/2 \hbar \omega. So it isn't zero.

Furthermore, in the deBoer effect for noble gasses, the specific heat actually increases as one gets closer to absolute zero, which is a direct consequence of the presence of zero-point energy/uncertainty principle.

Zz.
 

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