Pauli Exclusion Principle and Entanglement

g.lemaitre

How do fermions, which have vast amounts of empty space, know not to occupy the same space as another fermion? Do physicists say that the two fermions become entangled and that is what enables them to be "aware" of the "existence" of the other fermion? Is entanglement used as an explanation for how objects interact with each other?

Zarqon

I'm not sure what you mean by "vast amounts of empty space", but in my view, the Pauli exclusion principle doesn't come in until the wavepackets of the fermions in question start to overlap. The PEP is a quantum interference effect anyway and they "feel" it whenever the wavepackets overlap. If they don't overlap, then they don't have the same (spatial) quantum numbers, and they can have the same spin without a problem, i.e. there is no PEP.

g.lemaitre

So entanglement is not used to explain how particles are aware of each others' space?

kith

The wave function of a number of indistinguishable particles looks like the wave function of entangled particles. But you cannot perform entanglement measurements on them even in principle. In order to do this, you have to have distinguishable particles (like in EPR experiments, where the particles usually move in different directions).

See also Arnold Neumeier's FAQ: http://www.mat.univie.ac.at/~neum/ph...Entangled.html