How did ancient theories of matter evolve?

Karthik Gurumurthy

Question regarding natural phenomena and the physical world intrigued the ancient Greeks. The greatest philosophers tackled the question of the nature of the matter. Thales of Miletus,  who lived around 600 BCE, stated that all material things are aspects of one fundamental substance- water. He suggested that the amount of water in a substance gave it its unique characteristics.

Another Greek philosopher, Anaximenes, took exception to Thales’ argument, insisting that air was the fundamental material. Yet another philosopher suggested fire was the primary material. A century later, Empedocles of Sicily asked,  ” Why must there be just one basic substance?” He felt such a conception of matter was too simple. Rather, Empedocles believed that water, air, fire and earth were the four fundamental “elements” or building blocks, of matter.

Democritus (ca. 460-370 BCE) was a Greek philosopher who built upon the ideas of his teacher, Leucippus. Democritus said that matter is made up of solid “atoms” and empty space. Materials could be broken apart because of the spaces that exist between the atoms that compose the materials. If matter continues to be divided into smaller and smaller pieces, Democritus reasoned, one would eventually reach a point where the remaining materials could no longer be divided.

At this point, the remaining solid and miniscule particle would be “indivisible” or atomos in Greek. “Atoms” were indivisible.Democritus said, because they contained no remaining empty space. They were the smallest pieces of substances  that existed.  They were not only solid,  but they were indivisible to the naked eye. And they were all alike, that is, atoms were all  made from the same fundamental substance, regardless of  whether they had been obtained from rock, wood, leaves or flesh.What made various materials different from each other was the shape of their atoms  or the way those atoms were packed together.