What have Greeks to do with atoms? – Part I

The greek atom

Every time a chemistry teacher or a science TV show start to talk about atoms, they invoke ancient Greeks. Then, they jump over 22 centuries and, without any connection, start afresh from John Dalton. But is there any connection to be made? What do ancient Greeks have to do with atoms?

A visit to Abdera

If you paid attention to your classical studies, you should remember the Eleatic school with names like Zeno and Parmenides.  The Eleatics believed that the world is eternal, indivisible and unified, without plurality, evolution or motion; and that all transformations are illusions caused by our senses.

They attempted to prove their point by pointing out that there are paradoxes everywhere. They are like glitches in the Matrix indicating that what we take for reality is an illusion. Zeno, for instance, argued that in a race between Achilles and a tortoise, if the tortoise had a head start, Achilles would never been able to overtake it, even being faster, because every time he reached the last tortoise’s position, it would have already moved a bit more.

For Zeno, who would probably fail basic calculus, this and many other paradoxes were evidences that we live within an illusion and that the universe is a static homogeneous unity. One single giant atom, so to speak.

More or less at the same time, another philosophical school was being developed, the atomists, with names like Leucippus and Democritus of Abdera. The atomists believed in plurality and motion, but they also saw the glitches. Democritus himself described the following paradox:

“If a cone was cut parallel to the base, how should we understand the surfaces of the segments, as equal or unequal? If they are unequal, they will produce an uneven cone, with many jagged steps and rough edges; but if they are equal, the segments will be equal and the cone will turn out to have the same character as a cylinder, composed of equal rather than unequal circles, which is completely absurd”

The philosophy of Leucippus and Democritus tried to avoid the Eleatic monism by establishing a duality between being and not-being. The world for them is made of beings scattered through the not-being, or void.

I can imagine Democritus arguing with an Eleatic: “OK, I give you that: the being is indivisible and eternal, but there are infinite number of beings within the void”.

Then, it was missing only a name for these small, eternal indivisible bits of being. With surprising lack of imagination, Leucippus called them indivisibles, or atoms in Greek.

Everything that we learn through our senses is subjected to transformation. For the Eleatic, transformations are illusions; for the atomist, transformations are reflex of atoms moving within the void. In Democritus words:

“By convention sweet (exists), by convention bitter, by convention hot, by convention cold, by convention color, but in reality atoms and void.”

In particular, the atom should be very small, otherwise we would see it. We see only groups of atoms, which we call bodies. But although they are small, they should still have a finite size, otherwise, things wouldn’t have size either.

Leucippus went even far in his speculations. He imagined the whole creation of the universe in terms of fluxes of atoms in turbulent motion. Democritus brought this idea to the limit by postulating the existence of atoms with different forms and sizes, to explain the different substances that form everything, from things to (literally) gods.

In a glance, this is the Greek concept of atom.

Then, I can finally return to the question of the title: what do ancient Greeks have to do with atoms?

Well, apart of inventing the name, everything and (paradox!) nothing. It depends on how we are using the word atom. And there are still two other ways of doing it. I will come back to that in the next post, but I can already anticipate: if you are a chemistry teacher, you can safely skip the chapter about the Greeks.

MB

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Categories: Chemistry, History of Science, Philosophy of Science, Science

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  1. What have Greeks to do with atoms? – Part II | Much Bigger Outside
  2. As Small As an Atom | Much Bigger Outside

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