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I have heard Frank Close say that the reason you can't put your hand through a solid object is the Pauli exclusion principle. However Richard Feynman in his "Fun to Imagine" series attributes it to electrostatic forces.

I have two questions: Firstly, who is correct here (or maybe both)? Secondly, on a classical scale can the Pauli exclusion principle be interpreted as a force? The reason you can't put your hand through a solid object is because of a normal reaction force. So if the PEP is responsible for this it must be creating a force. I have sometimes seen the singularity at 0 in the Lennard-Jones potential interpreted as due to the PEP.

EDIT: I understand that the PEP is not a "fundamental force" carried by force-carrying particles. But it seems to clearly manifest as a force on a classical scale.

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Without Pauli exclusion your hand would go through a glass table or even fuse with it. There would be no chemistry as we know it. It seems unbelievable that the universe is stabilised by something regarded to be a mere consequence of symmetry.

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Close and Feynman are both right. If you try and overlap one electron-state with another then, thanks to the Pauli Exclusion Principle,this is impossible. One of the electrons must move to a higher state, which requires energy, which is why the Lennard-Jones potential shoots up, and there is a resistive force. The reason this state has a higher energy is that the electron involved is further from the nucleus, so its electrostatic potential energy is higher.

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