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The concept of the atom-the smallest physical building
block of nature-has been around at least since ancient Greece.
Leucippus and Democritus conceived of a mechanical
or physical atom; in the Middle Ages the Islamic
philosophers Ibn
Rushd and Agostino Nifo added a chemical
role to atomic theory. In the 17th century, Descartes'
mechanical philosophy extended the idea of a corpuscle moving
in a "plenum"; and Robert Boyle suggested the possibility
of subatomic particles.
During
the 18th and 19th centuries, atomic theory was involved in the
growing understanding of chemistry and in debates about whether
light is made of particles or waves. Atoms also
were used to theoretically explain electricity, especially after
J.C.Maxwell in 1873 showed that light, electricity, and
magnetism are all forms of electromagnetic radiation. J.J.
Thompson discovered the electron in 1897, stimulating interest
in the internal structure of the atom.
Prominent
models of the atom included Kelvin's vortex model
(1867), Thompson's plum pudding model (1904),
and Rutherford's nuclear model (1911). Experimental
and theoretical problems began to undermine classical physical
theory, and in 1900 Max Panck postulated the "quantum"-a
smallest possible unit of energy. Energy thus became
"atomized"; in 1905. Einstein's
studies of the photoelectric effect suggested that light
itself is atomized.
In
1912, Neils Bohr created an atomic model that has "rings"
of orbiting electrons, thus accommodating quantum theory and
the latest experimental results. Continued elaboration of this
model produced what's called the "Copenhagen Interpretation";
this conception of the atom explains experimental results yet
it abandons precise definition of atomic behavior, abandons
classical continuity in favor of quantum discontinuity,
uses statistics rather than unambiguous definition, and abandons
many traditional notions of determinism and causality.
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