# Question regarding the Pauli Exclusion Principle?

• zeromodz
In summary, the conversation discusses the Pauli Exclusion Principle and its application to protons and neutrons, which are both spin 1/2 fermions. The principle states that no two fermions can have the same quantum state, meaning their assortment of quantum numbers. This explains why protons and neutrons, which have different quantum numbers, can exist together in the nucleus of an atom without violating the Pauli principle. Additionally, when nucleons are pushed together, they are forced to occupy different energy states, resulting in electron degeneracy pressure that prevents them from collapsing in on themselves.
zeromodz
Okay, I think everyone here knows what the principle states, so I am not even going over that. Is a proton not a fermion with is +1/2 spin? It has an half integral, hence it must be. However, how is this possible for a proton to be fermion when elements like gold have a lot of protons in the nucleus.

These protons are pushed together by the atomic force, why don't they disappear because they have asymmetrical wave functions, hence they should cancel out?

The Pauli Exclusion Principle states that no two fermions can have the same quantum state. Quantum state meaning the assortment of quantum numbers that the wave function has in order to describe the system. Sure two protons can have the same total spin, but other things like their spin direction, i.e along the z-axis or the x-axis, or their principal quantum number ,which is their energy state, cannot be the same.

Anyway, yes protons and neutrons are spin 1/2 fermions that do obey the Pauli Exclusion Principle. Just with different quantum numbers other than total spin.

I hoped this helped

Easy. They're not in the same place or state.

If you were to push the nucleons together so they occupied the same space, then the Pauli principle would not lead to them 'disappearing'. (The fact that the wave function 'disappears' means it's an invalid wave function. It's not a solution to the S.E. It doesn't happen.) What happens if they're pushed into the same space is that they're then forced to occupy different (higher) energy states.

This manifests itself as http://en.wikipedia.org/wiki/Electron_degeneracy_pressure" . Which is what keeps neutron stars from collapsing in on themselves.

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Okay, I guess you guys answered it, but don't you think your pushing when you say out of all the atoms in the universe, every single proton has a different quantum state?

zeromodz said:
Okay, I guess you guys answered it, but don't you think your pushing when you say out of all the atoms in the universe, every single proton has a different quantum state?

No, because protons that occupy different positions are not in the same state so the EP does not apply; and the universe is a big place with plenty of space.

## 1. What is the Pauli Exclusion Principle?

The Pauli Exclusion Principle is a fundamental principle in quantum mechanics that states that no two identical fermions (particles with half-integer spin) can occupy the same quantum state simultaneously. This means that two electrons, for example, cannot exist in the same energy level in an atom.

## 2. Who discovered the Pauli Exclusion Principle?

The Pauli Exclusion Principle was first proposed by Austrian physicist Wolfgang Pauli in 1925. It was later confirmed by experiments and is now considered a crucial principle in understanding the behavior of atoms and molecules.

## 3. What are the consequences of the Pauli Exclusion Principle?

The Pauli Exclusion Principle has several important consequences, including explaining the stability of matter, the periodic table of elements, and the properties of atoms and molecules. It also plays a role in the formation of white dwarfs and neutron stars.

## 4. Is the Pauli Exclusion Principle violated in any circumstances?

No, the Pauli Exclusion Principle has been found to hold true in all known cases. However, there are some hypothetical situations, such as in the extreme conditions of a black hole, where it may not hold true.

## 5. How is the Pauli Exclusion Principle related to the Heisenberg Uncertainty Principle?

The Heisenberg Uncertainty Principle states that it is impossible to know the exact position and momentum of a particle at the same time. This is related to the Pauli Exclusion Principle because it is the reason why two identical fermions cannot occupy the same quantum state - if they did, we would have complete knowledge of their position and momentum, violating the uncertainty principle.

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