What Force Causes Electron Repulsion in the 1s State?

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SUMMARY

The discussion centers on the forces that cause electron repulsion in the 1s state, specifically addressing the Pauli Exclusion Principle (PEP) and the Heisenberg Uncertainty Principle (HUP). Participants assert that the PEP arises from the spin-1/2 nature of electrons and does not involve a force, while the HUP is derived from quantum mechanics axioms. The conversation highlights that both principles are theoretical constructs rather than experimental derivations, emphasizing their interdependence in quantum mechanics. Additionally, the concept of degenerate pressure in astrophysical contexts, such as white dwarf and neutron stars, is mentioned as a consequence of the PEP.

PREREQUISITES
  • Understanding of quantum mechanics principles, particularly the Pauli Exclusion Principle and Heisenberg Uncertainty Principle.
  • Familiarity with spin-1/2 particles and their implications in quantum states.
  • Knowledge of quantum field theory concepts, including fermions and the quantum vacuum field.
  • Basic grasp of experimental versus theoretical physics methodologies.
NEXT STEPS
  • Study the derivation and implications of the Pauli Exclusion Principle in quantum mechanics.
  • Explore the Heisenberg Uncertainty Principle in detail, focusing on its mathematical foundations.
  • Investigate the role of degenerate pressure in astrophysics, particularly in white dwarf and neutron stars.
  • Read Heisenberg's "Physical Principles of Quantum Theory" for foundational insights into quantum mechanics.
USEFUL FOR

Students and professionals in physics, particularly those focusing on quantum mechanics, theoretical physicists, and astrophysicists interested in the implications of quantum principles in stellar phenomena.

pivoxa15
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There must be a force repulsing the electrons for no more than two in the 1s state for example. What force is that?

How is this principle connected to the HUP?
 
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There is no force behind the exclusion principle -- until you get to phenomenological models in condense matter theory, which occasionally postulates such a fictitious force. The exclusion principle is solely due to the spin-1/2 nature of electrons.
 
And there's no connection with the HUP, since this follows from the axioms without considering the symmetrization/antisymmetrization of the state vector.
 
As the others said, there is no force behind the Pauli principle. In fact, the pauli prinicple can be the SOURCE of force, degenerate pressure; in for example White dwarf stars, and neutron stars.
 
I find that hard to believe. How then can particles know about the presence of the other?

There must be messenger particles of somesort?
 
dextercioby said:
And there's no connection with the HUP, since this follows from the axioms without considering the symmetrization/antisymmetrization of the state vector.

So the HUP is more fundalmental?

Is Pauli's exclusion principles derived experimentally or theoretically?
 
pivoxa15 said:
I find that hard to believe. How then can particles know about the presence of the other?

There must be messenger particles of somesort?

Welcome to the world of Quantum mechanics! =)
 
pivoxa15 said:
So the HUP is more fundalmental?

Is Pauli's exclusion principles derived experimentally or theoretically?

According to what I have learned (and my books do not mention anything else), it is derived theoretically. Just look it up in your QM books in the chapters on "Identical particles".



And what do you mean "more fundamental", the HUP is also derived from theory, not so very difficult either.
 
Pivoxa, it may help you to visualize the PEP this way. Imagine that a fermion is a condensation of the quantum vacuum field, and that the field has a "carrying capacity". In other words, the field cannot support the existence of two identical fermions in the same state. The fermions do not "know" where they are in relation to one another, nor do they repel one another - their failure to superimpose is a characteristic limitation of the field in which they arise. The existence of a fermion in a quantum state drives the probability of the existence of a same-spin twin in that same quantum state toward zero.
 
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  • #10
All physics is experimental -- otherwise it's maths. The uncertainty principle is was a *principle* when Heisenberg proposed it, extrapolating on experimental evidence; now, we tend to derived it, as a consequence of the formalism (Hilbert spaces and projection operators). What is theoretical in one view is experimental in another. If you're serious about wanting to learn about quantum mechanics, get a good book -- I recommend Heisenberg's original, Physical Principles of Quantum Theory, which is a short and cheap book.
 
  • #11
pivoxa15 said:
So the HUP is more fundalmental?

Is Pauli's exclusion principles derived experimentally or theoretically?

No, the HUP is a consequence of the axioms, the Pauli exclusion principle is a conseqance of the axioms as well. Therefore none is more fundamental than the other.
 

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