The Greek Concept of Atomos: The Indivisible Atom
Around 440 BC, Leucippus of Miletus, in his lost book "The Greater World System," originated
the atom concept. He and his pupil, Democritus (c460-371 BC) of Abdera, refined and extended
it in future years. There are five major points to their atomic idea. Almost all of the original
writings of Leucippus and Democritus are lost. About the only sources we have for their
atomistic ideas are found in quotations of other writers.
Democritus is known as the "Laughing Philosopher" because of his joyous spirit. He was a big
man (relatively speaking) and enjoyed life tremendously. He also was very widely traveled,
having reportedly visited Athens.
Democritus is widely credited with developing the atom concept. This is
incorrect. In fact, Democritus wrote his version in a (now lost) book
called "Little World System."
This map shows the important towns of
Greece, Turkey and Asia Minor around the
time the atom concept was developed. It is
about 250 miles as the crow flies between the
Abdera and Miletus.
At this time Greek philosophy was about 150 years old,
having emerged early in the sixth century BC, centered in
the city of Miletus on the Ionian coast in Asia Minor (now
Turkey). The earliest known Greek philosopher was
Thales of Miletus.
The work of Leucippus and Democritus was further
developed by Epicurus (341-270 BC) of Samos, who made the ideas more generally known.
Aristotle (384-322 BC) quotes both of them extensively in arguing against their ideas. Much of
what we know about their ideas comes to us in a poem titled "De Rerum Natura" (On the Nature
of Things) written by Lucretius (c95-55 BC). This poem, lost for over 1000 years, was
rediscovered in 1417.
The Greek Atomic Theory
Point #1- All matter is composed of atoms, which are bits of matter too small to be seen.
These atoms CANNOT be further split into smaller portions.
Atoms were impenetrably hard, meaning they could not be divided. In Greek, the prefix "a"
means "not" and the word "tomos" means cut. Our word atom therefore comes from atomos, a
Greek word meaning uncuttable.
Epicurus also insisted on an upper limit for atoms - they are always invisible. Although no
reason is given, it seems obvious enough: all matter that can be seen by humans is still divisible,
therefore cannot be atoms.
Point #2: There is a void, which is empty space between atoms.
Aristotle quotes Leucippus: "Unless there is a void with a separate being of its own, 'what is'
cannot be moved-nor again can it be 'many', since there is nothing to keep things apart."
In other words, there is empty space between atoms. In modern times, we would use the word
vacuum, although the Greeks did not.
Given that all matter is composed of atoms (the ultimate and unchanging particles), then all
changes must be as a result of the movement of atoms. However, in order to move there must be
a void--a space entirely empty of matter--through which atoms can move from place to place.
Point #3: Atoms are completely solid.
The absolute solidity of the atoms also leads to the notion that atoms are homogeneous, or the
same all the way through. Another way to express this is that an atom would have no internal
structure.
Point #5: Atoms are different in…
1) ...their sizes. See the Democritus quote just below.
2) ...their shapes. According to Aristotle: "Democritus and Leucippus say that there are
indivisible bodies, infinite both in number and in the varieties of their shapes...."
Democritus says of atoms: "They have all sorts of shapes and appearences and different sizes....
Some are rough, some hook-shaped, some concave, some convex and some have other
innumerable variations."
3) ...their weight. Again from Aristotle: "Democritus recognized only two basic properties of the
atom: size and shape. But Epicurus added weight as a third. For, according to him, the bodies
move by necessity through the force of weight."
Concluding Remarks
The Catholic Church came to equate atomistic ideas with Godlessness. For example,
"Democritus of Abdera said that there is no end to the universe, since it was not created by any
outside power."