Classical
physics explains matter and energy at the macroscopic level of
the scale familiar to human experience, including the behavior
of astronomical bodies. It remains the key to measurement for
much of modern science and technology; but at the end of the
19th Century observers discovered phenomena in both the large
(macro) and the small (micro) worlds that classical physics
could not explain. Coming to terms with these limitations led to
the development of quantum mechanics, a major revolution in
physics.
