Pauli exclusion principle at distance

In summary, the conversation discusses the Pauli exclusion principle and whether it applies over macro distances or only within a single atom or atoms in proximity. One side argues that the principle is valid even over vast distances, while the other side argues that it only applies in close proximity. The current understanding is that while the principle does apply to all identical particles in the universe, the effects are negligible for particles that are not in close proximity. However, it can have measurable consequences for large groups of particles, such as in a Bose-Einstein condensate.
  • #1
airydisc
4
0
Hi.

New member to this Physics forum and not a physicist, although have an interest in physics from a layman's position.

I saw a series of threads on a Twitter discussion posted about a year ago concerning Brian Cox and some other physicists concerning a statement made by Cox that the Pauli Exclusion principle work over macro distances, so that when an electron is excited in one part of the universe, all other electrons in the universe change their energy state, even if that change is at an imperceptible level. The argument was about whether there was a misunderstanding of the PEP, in that it should only work within a single atom or atoms in proximity so that there is an exchange of information between the two. One side states this is the case, the other side states that the PEP is valid even over vast distances.

Does anyone know what the current understanding of this issue is?

Many thanks

airydisc
 
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  • #2
The Pauli exclusion principle in a general form states that the wave function of identical fermions should be anti-symmetrized. In principle, the wave function of the electrons of a rock on Earth does depend on the electrons on the moon. However, the error made by ignoring the electrons on the moon is negligible. There is a quantitative discussion of this in Shankar's "Principles of Quantum Mechanics", p283.
 
  • #3
Ah OK. So suggesting that exciting electrons in a diamond on Earth forces electrons the other side of the Universe to alter their state so that they remain anti-symmetrized is theoretically correct, but in reality the impact is so tiny, its immeasurable. It only becomes measurable (and therefore a big enough deal) when the fermions are within close proximity, i.e. in a single atom or close group of atoms?
 
  • #4
Yes, roughly. However, the number of atoms to which it applies with consequences we can measure can be quite large. For example, the symmetrization of the wave function applies for 2000 atoms in a Bose-Einstein condensate. http://en.wikipedia.org/wiki/Bose–Einstein_condensate . (The Pauli exclusion is a different effect in which the wave function is anti-symmetrized for identical fermions, while in the Bose-Einstein condensate the wave function is symmetrized for identical bosons. Nonetheless, the idea the idea is the same in that the effect in principle applies to identical particles throughout the universe.)
 
  • #5
If we have 2000 atoms moving in a common potential well it the same as electrons in a single atom. So it does not make the point that PEP works for two particles that are confined to two separate potential wells.
 

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 fermions cannot have the same set of quantum numbers, such as energy, momentum, and spin, within a system.

How does the Pauli Exclusion Principle apply to particles at a distance?

The Pauli Exclusion Principle also applies to particles that are at a distance from each other. This means that even if particles are not in direct contact, they still cannot occupy the same quantum state. This is due to the fact that particles can interact and affect each other's quantum states even at a distance.

Why is the Pauli Exclusion Principle important in understanding the behavior of matter?

The Pauli Exclusion Principle is important because it explains the stability and properties of matter. It prohibits electrons from occupying the same energy levels and prevents atoms from collapsing. It also plays a crucial role in determining the electronic structure of atoms and the periodic table of elements.

Can the Pauli Exclusion Principle be violated?

The Pauli Exclusion Principle is a fundamental principle in quantum mechanics and has been extensively tested and confirmed through various experiments. So far, no violation of this principle has been observed. However, there are some theoretical scenarios where it may appear to be violated, such as in the presence of exotic particles like quarks and bosons.

What are the real-life applications of the Pauli Exclusion Principle?

The Pauli Exclusion Principle has many practical applications in various fields of science and technology. It is essential in understanding the properties of materials, such as electrical conductivity and magnetism. It also plays a crucial role in the functioning of electronic devices, such as transistors and computer memory. Additionally, the principle is applied in nuclear physics, astrophysics, and chemistry, among other fields.

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