What mechanism provides the internal pressure inside a neutron star? a. ordinary pressure from hydrogen and helium gas b. degeneracy pressure from neutrons c. degeneracy pressure from electrons d. rapid rotation

Inside a neutron star, the internal pressure is not like that of ordinary matter. It's primarily supported by a special kind of pressure called neutron degeneracy pressure. This pressure arises because of the extremely high density of a neutron star.
Imagine a vast number of neutrons squeezed into an incredibly small space. This situation is fundamentally governed by quantum mechanics. In particular, it's the degeneracy pressure from neutrons that plays a crucial role.
Degeneracy pressure is a resistive force that prevents neutrons from being packed too tightly together. It's a quantum mechanical effect that becomes significant only in very dense environments like those found inside neutron stars.

The Pauli exclusion principle is a key concept in understanding neutron degeneracy pressure. It's a fundamental principle in quantum mechanics that states no two fermions (particles like electrons, protons, and neutrons) can occupy the same quantum state simultaneously.
This principle is what causes degeneracy pressure. Because neutrons are fermions, they can't all be crammed into the lowest energy state. Instead, they have to occupy higher energy states, effectively creating a pressure that resists further compression.
In the case of neutron stars, this exclusion principle ensures that neutrons can't be squeezed into the same quantum state, providing the necessary pressure to counterbalance the immense gravitational forces trying to crush the star further.

Neutron stars are born from the dramatic events of supernova explosions. When a massive star exhausts its nuclear fuel, its core collapses under gravity, and this collapse triggers a supernova.
The outer layers of the star are blasted away, leaving behind a dense core. If this core's mass surpasses the Chandrasekhar limit but isn't enough to form a black hole, it forms a neutron star.
The remaining core, now a neutron star, is the remnant of the supernova explosion. This remnant is incredibly dense and small, typically around 20 kilometers in diameter, yet containing more mass than our Sun. The internal pressure from neutron degeneracy pressure ensures the neutron star remains stable despite its compact size and massive gravitational forces.