Atoms, of course, have existed since the beginning of time. Man's study of them, however, did not begin until considerably after that.

The word atom was coined somewhere around 450 B.C. (it is an unfortunate side note about this period of history that it is usually quite difficult to give precise dates; one wishes that the ancient Greeks would have been a little bit better at keeping track of their activities) by a philosopher (which, at the time, was the same thing as a scientist) named Democritus.

What is Known about Democritus

Democritus was a student of Leucippus, who is said to also have subscribed to the atomic theory, though so very little is known about the actual works of both of these men that it becomes very difficult to tell where the theories of one ends and the other begins. Leucippus was said to have been influenced greatly by his contemporary, Zeno of Elea, which may explain some of his iconoclastic views on the substance of things.

While Leucippus is credited by many to have been the true “creator” of atomic theory, he is more often than not overshadowed by Democritus, who did much more to systematize this view. Though there was still not much to it.

Just as the sand on the seashore, so went the logic of Democritus, when viewed from afar looks to be a single body – a “beach” – so also may all matter be made up of tiny little granules of matter – the smallest of which he called atoms, which in Greek means, “uncuttable.” By virtue of the name itself, an atom in Democritus’ theory was the smallest thing in existence.

It is difficult to say just how “scientific” atomic theory was in the case of Democritus – was it a real theory, developed using something similar to today’s scientific method, based on factual observation and deductive logic? Or was it a lucky shot in the dark? The jury is still out on this one, though one must give Democritus credit for his undeniably witty observation, “Nothing exists except atoms and empty space; everything else is opinion.”

Opposition to Democritus

Nevertheless, the view of Democritus was greatly overshadowed by the theories of Aristotle, which viewed the entire known universe as being made up of five distinct “elements” (earth, fire, air, water, and ether) which mixed and matched to form anything of substance. In his theory was no need for everything to be made of tiny little atoms, so the view of Democritus was largely ignored.

One may be quick to judge Aristotle and the rest of the “scientific” community of the time for so quickly dismissing the views of Democritus (which are now known to be, to a certain extent, more correct), but this would be a bit near-sighted. The truth is that in the world of the ancient Greeks, there truly was much more evidence for the views of Aristotle than that of Democritus. There was much more reason to believe that everything tangible was made up of at least four of these elements (the fifth element, ether, was not quite so scientifically based, but was founded on much more pseudo-religious grounds concerning the perfection of the heavens and corruption of the Earth, but that is another story altogether), than there was to believe in these tiny things that could not possibly be seen.

The Legacy of Aristotle and Democritus

Because of the logic inherent in Aristotle’s views, as well as the fact that as the foremost scholar of his day many of his views went almost entirely unchallenged, the atomic view of Democritus faded away and Aristotle’s view increased in popularity to the point where it was nearly heretical to question it.

And so things would remain for more than two thousand years. Even as other principles of Aristotle (the geocentric view of the universe, the law of gravity, the concept of light) finally began to be questioned by the likes of Galileo, Copernicus, Kepler and Newton, his theory on matter remained.

It was not until the nineteenth century(!) in fact, that Scientists finally began to give the ideas of Democritus a second look.

To find out where atomic theory went from here, Read about John Dalton.

Further Reading:

Democritus and Ancient Atomic Theories

John Dalton and the First Modern Atomic Theory

Brownian Motion and the Proof of Atoms

The Scale of Atoms

J.J. Thompson and the Discovery of Electrons

Ernest Rutherford and the Discovery of Protons and the Atomic Nucleus

James Chadwick and the Discovery of the Neutron

References:

Asimov, I. (1966). Understanding Physics: 3 Volumes in 1. Barnes and Noble Books.

Gribbin, J. (2002). The Scientists: A History of the Science Told Through the Lives of its Greatest Inventors. New York: Random House.

Isaacs, A. (2003). Dictionary of Physics. London: Grange Books.