Quantum Physics: the Pauli exclusion principal (General)

by David Turell , Thursday, October 12, 2023, 17:40 (198 days ago) @ David Turell

Explained:

https://www.sciencealert.com/what-is-the-pauli-exclusion-principle?utm_source=ScienceAl...

"The Pauli exclusion principle is a rule in quantum mechanics that explains why only a limited number of electrons can occupy any one of an atom's orbitals.

"Predicted by Austrian theoretical physicist Wolfgang Pauli in the 1920s, the exclusion principle underpins basic chemistry, and helps explain why massive objects like neutron stars and white dwarfs resist gravity crushing them into infinitely small black holes.

"Pauli's exclusion principle states two or more bound electrons can't have the same four quantum numbers when in the same system. Particles with the same energy, magnetic quantum number, intrinsic angular momentum, and orbital angular momentum simply cannot sit in the same seat around an atom's center stage.

"The reason for this is more a feature of mathematics than anything, so it can be a little hard to picture.

"To appreciate it, we need to stop thinking of electrons as tiny solid objects (like the picture below on the left) and remember they are more like flickering 'ghosts' that haven't really worked out where to appear yet.

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"One is that any two particles sitting at the same level of energy around a nucleus – with otherwise identical characteristics – would behave nothing like electrons.

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"a fundamental part of an electron's wave-like behavior forbids them from overlapping perfectly with one another. It's a principle of identity that applies not just to electrons but to all subatomic particles that belong to the group of fermions. (My bold)

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"Astronomers also note the consequences of this exclusion principle – it takes an incredible amount of energy to force electrons into spaces they don't typically move in, such as the inside of protons, which helps explain the workings of exotic objects like neutron stars. Push hard enough, and they may even lose all identity, mushing together into the space of a black hole's core."

Comment: the key is the bolded paragraph which tells us electrons repel other electrons very strongly. In an atom, electrons will occupy different orbits if another orbit is filled with its electrons.