Exclusion Principle - why doesn't degneracy balance weight?

[AlfaFoxtrot]

Fairly simple question, I just couldn't think of a suitable explanation for it.

In white dwarfs, neutron stars etc gravity is balanced by high outward pressure of fermions, which are in a confined space, so have v. high velocities. My question is, if you placed a heavy weight on an ordinary chair, it doesn't go straight through the chair because of the electrostatic repulsion of electrons, but also the PEP repulsion as they are being squeezed closer together. So why does a chair break when a weight too heavy is put on it? Surely the PEP repulsion just increases as electrons are moved closer together, thereby balancing the weight and not putting any stress on the chair?

I'm sure the explanation is dead simple, and I'm currently thinking it's a equal-opposite reaction kind of thing. Thanks in advance for any replies...

 

[Nate810]

The reason why a chair breaks when a weight too heavy is placed on it is because the electrons in the chair are not able to resist the pressure of the weight due to their limited mass. The Pauli Exclusion Principle (PEP) does increase the repulsive force between the electrons, but it is not enough to oppose the weight which produces a net force that is greater than the force of the PEP repulsion. This net force causes the chair to eventually break.

 

[m2003]

The exclusion principle, also known as the Pauli exclusion principle, states that no two fermions (particles with half-integer spin) can occupy the same quantum state simultaneously. This principle is a fundamental concept in quantum mechanics and plays a crucial role in understanding the behavior of matter at a microscopic level.

In the case of white dwarfs and neutron stars, the exclusion principle plays a crucial role in balancing the weight of the object. As you mentioned, the high outward pressure of fermions, such as electrons, is able to counteract the force of gravity due to their confined space and high velocities. This is because the exclusion principle prevents these fermions from occupying the same quantum state, thus creating a strong repulsive force.

However, the exclusion principle alone cannot explain why a chair breaks when a weight too heavy is placed on it. This is because the chair is made up of atoms, which are composed of a nucleus (containing protons and neutrons) surrounded by electrons. The exclusion principle only applies to fermions within the same atom and does not account for the interactions between different atoms.

When a heavy weight is placed on a chair, the atoms in the chair are compressed and pushed closer together. This results in the electrons in the atoms being forced into smaller orbits around the nucleus, which increases the repulsive force between them. However, this increase in repulsive force is not enough to counteract the weight of the object, and the chair ultimately breaks.

In summary, the exclusion principle plays a crucial role in balancing the weight of objects such as white dwarfs and neutron stars, but it is not the only factor at play in the breaking of a chair under a heavy weight. The interactions between different atoms and their electrons also play a significant role in determining the strength and stability of a material.