Proving Unachievability of Absolute Zero: Uncertainty Principle

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Discussion Overview

The discussion revolves around the question of whether the uncertainty principle can be used to prove that absolute zero is unachievable. Participants explore the implications of quantum mechanics on the concept of absolute zero, particularly in relation to energy and motion of particles.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions if the uncertainty principle is sufficient to demonstrate that absolute zero cannot be achieved, suggesting that a particle cannot have exactly zero energy.
  • Another participant explains that the uncertainty principle relates measurable quantities and argues that if the ground state energy is not zero, then absolute zero cannot be reached.
  • Some participants assert that quantum mechanical effects imply that particles will still exhibit motion at absolute zero, countering the misconception that absolute zero equates to no motion.
  • A later reply seeks clarification on the definition of absolute zero, prompting a discussion on whether it is defined as "zero kinetic energy" and thus "zero motion."

Areas of Agreement / Disagreement

Participants express differing views on the relationship between the uncertainty principle and the concept of absolute zero, with no consensus reached on whether absolute zero can be considered achievable or not.

Contextual Notes

Participants have not fully defined their terms, such as "absolute zero," leading to potential ambiguity in the discussion. The relationship between ground state energy and absolute zero remains unresolved.

Archosaur
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Is the uncertainty principle enough to prove that absolute zero is unachievable? i.e. a particle can't be said to have exactly zero energy, because it can't be said to have exactly any amount of energy.
 
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The uncertainty principle relates tells us how we can relate two quantities we can measure.

A better way to understand is that for any given wave function in a determinant state of the Hamiltonian the lowest amount of energy is the ground state. If the ground state energy is not zero then it can't be absolute zero by default.
 
No, but quantum mechanical effects mean that things (=atoms etc) will move even AT absolute zero (it is a common misconception that absolute zero means no motion).
 
f95toli said:
No, but quantum mechanical effects mean that things (=atoms etc) will move even AT absolute zero (it is a common misconception that absolute zero means no motion).

Well how are you defining absolute zero?
 
I would think "zero kinetic energy" and thus "zero motion", no?
 

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