Given that the electrical force is so much stronger than gravitational force at atomic levels, why is it that it's the gravitational force between you and the earth that keeps you on the ground rather than the electrical force between you and the earth?
Gravitational force is what keeps us on the ground rather than electrical force because there's no negative gravitational mass. Electric charge can be neutralized, while gravitational attraction not.
Actually, if you were at rest on the ground, the van der Waals repulsion between the atoms of the soles of your feet and the atoms of the ground — which is electrical in origin — exactly cancels the gravitational force between your entire body and the entire mass of the Earth.
And the van der Waals force isn't even a direct Coulomb force between two simple charges, but a much weaker indirect electrical repulsion between neutral atoms due to a deformation of the electron clouds. I know you might argue the repulsive van der Waals force is actually due to the Pauli exclusion principle, and that is also true. After fixing the positions of the nuclei, the physical ground state — which is given by a totally antisymmetric electron wavefunction — has a higher energy than some unphysical electron wavefunctions which aren't totally antisymmetric. But if we restrict ourselves to the physical wavefunction, the immediate repulsive force can still be traced back to electrostatics.
You write "rather than the electrical force between you and the earth". There is no electrical force between you and the earth because neither of you is charged! But you and the earth do both have mass so gravity acts but electricity doesn't.
"that the electrical force is so much stronger than gravitational force at atomic levels'" is only true between two charged particles of say the mass of a proton and the charge of a proton.
protected by ACuriousMind♦ Nov 15 '16 at 17:25
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