In physics, a quantum is the minimum amount of any physical
entity involved in an interaction. Behind this, one finds the fundamental
notion that a physical property may be "quantized," referred to as
"the hypothesis of quantization". This means that the magnitude can
take on only certain discrete values. There is a related term of quantum
number. An example of an entity that is quantized is the energy transfer of
elementary particles of matter through bosons and of photons.
A photon is a single quantum of light, and is referred to as
a "light quantum". The energy of an electron bound to an atom is said
to be quantized, which results in the stability of atoms, and of matter in
general. As incorporated into the theory of quantum mechanics, this is regarded
by physicists as part of the fundamental framework for understanding and
describing nature at the infinitesimal level.
Normally quanta are considered to be discrete packets with
energy stored in them. Max Planck considered these quanta to be particles that
can change their form. This phenomenon can be observed in the case of black
body radiation, when it is being heated and cooled.
