One of the earliest atomicity was Democritus, an ancient Greek philosopher who lived sometime in the 5th century BC. Democritus once stated that matter must be made up of “indivisible and continuous atoms”. One of Democritus best known works is his treatise on physics and natural philosophy, which he wrote in 391 BC. Democritus likewise was the first person to postulate the idea that all matter is made up of “indivisible and continuous atoms” (which he called “atom”). In other words, Democritus believed that matter consisted of “universals” that were subject to all of the laws of physics.
Another one of Democritus greatest works is his treatise on the nature of atoms. The most important part of this work is his model of how an atom should move when placed at rest along with other atoms. This was a vast improvement over earlier views held by the ancients including Aristotle and Hippocrates. According to Democritus, an atom was made up of four elements which were “rudely” arranged. These elements were hydrogen, oxygen, carbon and sulphur. These elements were mutually inseparable and Democritus was quick to point out, “An atom cannot be placed at rest nor be put into motion”.
Democritus was a big proponent of atheism. He was so great that even Aristotle, who was not particularly a great follower of atomism, acknowledged the Democritian atomistic philosophy as his own. However, even the great scientist Linus Pauling did not completely endorse Democritus’ ideas about atoms.
In the second half of the fourth century BCE, a very popular teacher named Aristotle began to develop a different model of how atoms worked. His basic idea was that all elements were made up of several common elements. However, the different elements did not consist of distinct atoms. Each element was composed of many similar elements. In his view, atoms could be thought of as “plants” that had grown together.
With the advent of modern technology and the advent of electricity, Aristotle was able to prove that Aristotle was wrong. Modern atomists now accept that each atom is composed of numerous positively charged protons, but have no knowledge as to whether these protons are bound together or whether they move freely. Atomists have further developed a model of the physical world called “atoms” wherein there is no such thing as time. Thus, it is believed that Democritus’ three ideas – that matter consists of unities and that time is a fabrication of the physical world, are false.
Democritus also denied that there was a physical law by which all atoms were known. Instead, he relied on analogies to explain how various atomic substances behave. For example, he illustrated how hot water evaporates when it is exposed to an excess of heat. The heat will cause the molecules in the water to expand until they reach a temperature of absolute zero. Similarly, he used analogies to explain how substances like rock do not come to an end – rather they continue to increase in volume until they reach some kind of natural limit known as the “critical point.”
After his death, Lavoisier realized that Democritus’ three-step process for atomism was not adequate to account for the structure of atoms. He thus concluded that Democritus must have used something more than simple comparison and analogy. According to Lavoisier, the “anatomy of matter consists in determining the arrangement and combination of its elementary atoms.” This was actually the first concept that modern science eventually adopted and put into practice. Lavoisier’s basic arguments concerning the structure of atoms were later adopted and developed by Isaac Newton and Galileo.
In our current age, nearly two hundred years after his death, Lavoisier’s original model for the atom has been incorporated into almost all existing theories of the universe. Even the most-discovering cosmologists have incorporated Lavoisier’s model into their own theories. The modern interpretation of Lavoisier’s original three-step method is called the Laplacean theory of the atom. Most modern philosophers agree with Lavoisier’s original three-step process model. The debate over his theory continues to this day.