Electrostatic and gravitational forces

[Ranku]

An object on the surface of the ground does not penetrate the ground. How much is this because of the electrostatic force between the particles constituting the ground and the object, and thereby maintaining their integrity? And, how much is it because of the materiality of the mass of the particles constituting the ground and the object and the gravitational force between them?

 

[vanhees71]

One important aspect to the answer of this question is quantum mechanics, and particularly also the Pauli exclusion principle. It's not possible to understand the existence of stable bulk matter from a classical microscopic point of view to begin with. It's not even possible to understand the existence of a stable hydrogen atom without quantum mechanics!

 

[PeroK]

An object on the surface of the ground does not penetrate the ground. How much is this because of the electrostatic force between the particles constituting the ground and the object, and thereby maintaining their integrity? And, how much is it because of the materiality of the mass of the particles constituting the ground and the object and the gravitational force between them?

If you imagine a particle that interacts with the Earth gravitationally but not otherwise (no electric charge for example), then that particle would pass right through the Earth.

There may be such particles that constitute the dark matter that makes up the missing mass of the galaxies. These particles would not clump together like ordinary matter into stars and planets but would ghost straight through stars and planets.

 

[Ranku]

If you imagine a particle that interacts with the Earth gravitationally but not otherwise (no electric charge for example), then that particle would pass right through the Earth.

There may be such particles that constitute the dark matter that makes up the missing mass of the galaxies. These particles would not clump together like ordinary matter into stars and planets but would ghost straight through stars and planets.

Just to clarify, given that the object is grounded and electrically neutral, is there any electrostatic interaction between the object and the ground?

 

[PeroK]

Just to clarify, given that the object is grounded and electrically neutral, is there any electrostatic interaction between the object and the ground?

There must be, otherwise the particle would fall through the centre of the Earth - and exhibit SHM.

For atoms, the force is the electrostatic repulsion of the electron shells, for example.

 

[Delta2]

The mystery of contact forces: Electromagnetic interaction or Pauli Exclusion Principle?

 

[Nugatory]

Just to clarify, given that the object is grounded and electrically neutral, is there any electrostatic interaction between the object and the ground?

Electromagnetic interactions are responsible for just about all of the bulk properties of any chunk of matter, including the object and the ground underneath it. These interactions are between the charged particles (electrons and atomic nuclei) that make up the matter and they are present even if the matter in bulk is electrically neutral (positive charges on nuclei balanced by equal number of negative charges from electrons).

These interactions are why the object is a solid instead of a gas or a liquid, why the ground is something we can stand on instead of a cloud of dust particles, and it is electrical forces between the particles in the ground and particles in the object that resist our efforts to push the object into the ground.

 

[vanhees71]

All this however works only within quantum theory. Classically one cannot account for the stability of matter as we know it!