Free electrons at zero kelvin?

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    Electrons Kelvin Zero
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Discussion Overview

The discussion centers around the behavior of free electrons at absolute zero (zero kelvin), particularly focusing on their energy states, movement under electric fields, and the implications of fermionic properties at this temperature. The scope includes theoretical considerations and conceptual clarifications related to quantum mechanics and solid-state physics.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether free electrons can exist at zero kelvin, suggesting that they should have zero energy but still be able to move under an electric field.
  • Another participant asserts that fermions cannot reach absolute zero due to the Pauli exclusion principle, implying that they will always possess some energy.
  • A different viewpoint clarifies that at zero temperature, particles occupy the lowest possible energy states, and while they may have energy, this does not contribute to temperature. It is noted that electrons can still have velocity even at near-zero temperatures.
  • A later reply challenges the definition of free electrons, arguing that if they are influenced by a positive potential, they cannot be considered free. The participant also discusses the context of conduction electrons in metals at zero kelvin, suggesting they are free to move within the conduction band.

Areas of Agreement / Disagreement

Participants express differing views on the nature of free electrons at zero kelvin, with no consensus reached on whether they can exist as free entities under the influence of an electric field. The discussion remains unresolved regarding the implications of fermionic behavior at absolute zero.

Contextual Notes

There are limitations in the definitions and assumptions regarding "free electrons" and their behavior in different materials, particularly metals. The discussion does not resolve the complexities of energy states and movement at zero kelvin.

chewchun
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At zero kelvin,are there free electrons?

At zero kelvin,the free electrons should have ZERO energy.But they are able to move under the influence of a electric field?
But when they are attracted towards the positive potential shouldn't they gain K.E? So they are moving at zero kelvin?
 
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you cannot send fermions at such temperature (they won't ever reach 0 K), just because they are fermions and must obey Pauli's exclusion principle they will have energy from that...
 
Zero temperature just means that all particles reach the lowest-possible states. In terms of fermions, they still have energy compared to the ground-state, but this energy does not contribute to temperature.
Note that this definition does not include any "velocity". You can have a collection of electrons at (close to) zero temperature, moving in one direction in your lab.
 
chewchun said:
At zero kelvin,are there free electrons?

At zero kelvin,the free electrons should have ZERO energy.But they are able to move under the influence of a electric field?
But when they are attracted towards the positive potential shouldn't they gain K.E? So they are moving at zero kelvin?

I do not understand your issue here. By definition, free electrons as ... FREE! If they are attracted to a "positive potential", then they are NOT free electrons in the first place!

So are they free, or aren't they? And where are these "free electrons" that you are considering? A metal? A metal's band structure is often calculated at 0 K! So the conduction electrons are in the conduction band at 0 K! They are free to move!

Zz.
 

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