nuclear physics

By definition, fermions are particles which obey Fermi-Dirac statistics: when one swaps two fermions, the

wavefunction of the system changes sign.[1] This "antisymmetric wavefunction" behavior implies that
f
ermions are subject to the Pauli exclusion principle — no two fermions can occupy the same quantum

state at the same time. This results in "rigidity" or "stiffness" of states which include fermions (atomic

nuclei, atoms, molecules, etc.), so fermions are sometimes said to be the constituents of matter, while

bosons are said to be the particles that transmit interactions (force carriers), or the constituents of

radiation. The quantum fields of fermions are fermionic fields, obeying canonical anticommutation

relations.

The Pauli exclusion principle for fermions and the associated rigidity of matter is responsible for the

stability of the electron shells of atoms (thus for stability of atomic matter) and the complexity of atoms

(making it impossible for all atomic electrons to occupy the same energy level), thus making complex

chemistry possible. It is also responsible for the pressure within degenerate matter which largely governs

the equilibrium state of white dwarfs and neutron stars. On a more everyday scale, the Pauli exclusion

principle is a major contributor to the Young modulus of matter.

All known fermions are particles with half-integer spin: as an observer circles a fermion (or as the fermion

rotates 360° about its axis) the wavefunction of the fermion changes sign. In the framework of

nonrelativistic quantum mechanics, this is a purely empirical observation. However, in relativistic quantum

field theory, the spin-statistics theorem shows that half-integer spin particles cannot be bosons and

integer spin particles cannot be fermions.[2]

In large systems, the difference between bosonic and fermionic statistics is only apparent at large

densities when their wave functions overlap. At low densities, both types of statistics are well

approximated by Maxwell-Boltzmann statistics, which is described by classical mechanics.

If thse ques r not going to come in exams, then why r u answering these ques and wasting your time ?????

not wasted , just copied and pasted.

Copy and paste is too a wastage of time.
It wastes abt 1-2-3 mins.