The Nature of Matter
A visitor from outer space, taking his first look at our world from high in the sky, might very easily think that the countryside was filled with a series of channels through which flowed a curious black liquid. From his position high above the earth he might not realize that he was looking down on a stream of cars moving bumper to bumper along a congested road on their way home from the seaside. On taking a closer look he would perhaps be able to detect that the 'liquid' was in fact made up of separate moving objects. Some of these objects would be moving faster than others, and now and then an object would leave the main stream and travel along on its own, while occasionally two or more of the objects would collide! The space man would not find it easy to form any idea why or how all this was happening.
Any conclusions he offered in a report to his own world could only be based on the facts he had observed.
The early Greek philosophers were in much the same position as our space visitor when they attempted to think about the nature of matter. They were unable to observe matter close up and could only guess why and how it acted as it did. One of them, Democritus (5th century BC), believed that matter was made up of indivisible atoms (from the Greek word atomos which means something that cannot be divided). It was not a popular idea for it also suggested that the gods of the Ancient World were not in complete control of the movement of these atoms and this, to the Greeks of that time, was certainly unthinkable.
Little progress was made in the understanding of the nature of matter for nearly 2,000 years. Then, in the middle of the 16th century, a Dominican monk, Giordano Bruno (1548-1600), attempted to revive the atomic theory. He was, as it happened, burned at the stake for his 'outlandish' ideas and it was left to Pierre Gassendi (1592-1655), a French philosopher and mathematician, again to suggest that matter was made up of moving atoms. Gassendi was careful to explain that in his view atomic movement was under the complete control of God.
This made his theories acceptable, but still almost impossible to prove one way or the other.
Today, with modern electron microscopes, we can examine the structure of matter much more closely and obtain some direct evidence of the existence of atoms, though even now we cannot actually see them as. separate particles. We have still not moved as close to the atom as our imaginary space visitor to the line of cars on earth. But there is no need to see these atoms directly, for their existence has been confirmed in many ways, and they have enabled scientists to explain chemical and physical phenomena.