It is interesting to note that some
people divide physics using Planck’s dis-
covery: The term classical physics is often
referred to as “before Planck”; while the
term for modern physics is often referred
to as “after Planck.”What is quantum mechanics?
Quantum mechanics is a branch of quan-
tum theory that simply determines the
probability of an event happening, al-
though the mathematical calculations to
prove such things are very rigorous and
complex. In fact, quantum mechanics is
often called the “final mathematical for-
mulation of the quantum theory.” Devel-
oped during the 1920s, it accounts for
matter at the atomic level and is consid-
ered an extension of statistical mechanics,
but is based on quantum theory. One
important part of quantum mechanics is
wave mechanics,which is an extension of quantum mechanics based on Schrödinger’s
equation. This idea states that atomic events can be explained as interactions between
particle waves. (For more on Erwin Schrödinger, see “History of Mathematics.”)What is the Pauli exclusion principle?
Quantum theory also relies on the Pauli exclusion principle. This principle, developed
by Austrian-born Swiss physicist Wolfgang Pauli (1900–1958) in 1925, states that two
particles of a certain class—called femions, and otherwise known as electrons, neu-
trons, and protons—can never be in the same energy state. For example, two elec-
trons with the same quantum number can’t occupy the same atom.What is the Heisenberg uncertainty principle?
German physicist Werner Karl Heisenberg (1901–1976) not only helped with the
quantum theory of light waves, he also developed the Heisenberg uncertainty princi-
ple. This states that it is impossible to determine, at the same time, both the energy
and velocity of a particle.How else is mathematicsused in physics?
There are hundreds of other applications of mathematics in physics. The following
282 lists only a few:
Physicist Max Planck was the first to propose the idea
that energy existed in bundles called “quanta.” His
theories later led to the development of quantum
mechanics and modern physics. Library of Congress.