Philosophers of Ancient Greece reasoned that all matter in the universe must
be composed of fundamental, unchangeable, and indivisible objects, which they
called "atoma" ("ατoµα").
The exact nature of these atoms remained elusive,
however, despite centuries of attempts by alchemists to create a
"philosopher's stone" that could transmute atoms of lead to gold, prove the
Greeks wrong, and make its inventors very rich. It was only in the late
1890s and the early twentieth-century that this view of a solid atom,
bouncing around the universe like a billiard ball, was replaced by an atom that
resembled more a miniature solar system, its electrons orbiting around a small
nucleus. Explorations into the nature of the atom from 1919 to
1932 confirmed this new model, especially with Ernest
success in finally transmuting an atom of one substance into another and with
James Chadwick's 1932 discovery of the elusive final basic particle of the atom,
the neutron. From 1932 to 1938,
scientists around the world learned a great deal more about atoms, primarily by
bombarding the nuclei of atoms and using a variety of particle
accelerators. In 1938, word came from
Berlin of the most startling result of them all: the nucleus of an atom could
actually be split in two, or "fissioned." This breakthrough was
quickly confirmed in the United States
and elsewhere. According to the theories of Albert Einstein, the fission of an atom
should result in a release of energy. An "atomic bomb"
was now no longer just science fiction -- it
was a distinct possibility.
To learn more about any of these events associated with the early years of
atomic research, choose a web page from the
To continue with a quick overview of the Manhattan Project, jump ahead to the
description of "Early Government Support"
provided uranium research from 1939-1942.
Sources and notes for this page.
The text for this page is original to the Department of Energy's Office of History and Heritage Resources.
The meaning of the word "atoma" is from the entry on
"Democritus" in The Concise Oxford Companion to Classical
Literature, edited by M. C. Howatson and Ian Chilvers (New York:
Oxford University Press, 1993), 167-168. Click here for more information on the
comic book image. The atom graphic is a combination of
graphics that were originally produced by the Washington
State Department of Health (the nucleus) and the Environmental
Protection Agency (everything else); the combination of the two
graphics, the labels, and other customizations, are original to the Department of Energy's Office of History and Heritage Resources. The fission
graphic is adapted from a graphic originally produced by the Washington
State Department of Health; the modifications are original to the Department of Energy's Office of History and Heritage Resources.
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