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Transcript: Empedocles supposed that all material was composed of four fundamental substances, earth, air, fire and water, and that everything we see in nature was either these primordial substances alone or seen in combination.  This ancient idea is the first signs of something that we would today recognize as the periodic table.  The Greeks also imagined there was a fifth, ethereal element that corresponded to the outer Celestial Sphere: quintessence.
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Transcript: In the year 584 B.C., on the coast of Asia Minor, two warlike tribes were engaged in a fierce battle: the Medes and the Lydains. As written by the Greek poets, these two cultures were hacking away at each other on the battlefield with burnished swords and shields, when suddenly the...
Published 07/12/11
Transcript: Thales was a philosopher who lived in the 6th century B.C. in Miletus, in what is now Turkey. No written work by Thales survives, but we know that he kept accurate eclipse records and he speculated about astronomy. He decided that the source of all things was one thing, and that...
Published 07/12/11
Transcript: The apparent motions of the stars in the night sky depend on your position on the Earth’s surface. At a northern temperate latitude, the stars rise in the east and set in the west, and they travel on slanting paths across the sky. The north celestial pole sits in the northern sky...
Published 07/12/11