It’s the first Friday of the month, which means another installment about the history of atom theory from physics professor and my dad, Dean Zollman. Here, atoms become the subject of Roman poetry. The theory might have gotten more traction if the poet had only stuck to science.—Kim
By Dean Zollman
Try this experiment at home. Find a small, bright beam of light. Sunlight coming through a small opening or the light from a video projector will do. Looking from the side of the beam, watch the motion of small particles of dust in the beam. You will see that the dust particles seem to bounce around in a somewhat random way. This motion indicates that the dust particles are colliding with invisible atoms in the air.
The effect was described by Robert Brown in 1827 and thus is called Brownian motion. The atomic explanation was presented by Albert Einstein in 1905. The discovery and explanation are considered critical events in establishing the existence of atoms.
Rewind the tape about 2,000 years. Lucretius, a Roman who died in about 55 BCE, wrote an epic poem, On the Nature of Things (De rerum natura). In this poem, Lucretius describes the science and philosophy of Epicurus, a Greek who lived about 200 years earlier.
The poem is divided into six books and is about 7,500 lines long. Books 1 and 2 describe Epicurean concept of atoms. Built on the ideas of Democritus, Epicurus added some features particularly about weight, density, and motion. He even connected the motion of atoms to free will. Lucretius was a follower of Epicurus and wrote his epic poem in Latin to convince Romans of the value of this philosophy.
Book 2 contains the following:
There’s a model, you should realize,
A paradigm of this that’s dancing right before your eyes—
For look well when you let the sun peep in a shuttered room
Pouring forth the brilliance of its beams into the gloom,
And you’ll see myriads of motes all moving in many ways
Throughout the void and intermingling in the golden rays
Your attention to the motes that drift and tumble in the light:
Such turmoil means that there are secret motions, out of sight,
That lie concealed in matter. For you’ll see the motes careen
Off course, and then bounce back again, by means of blows unseen,
Drifting now in this direction, now that, on every side.
You may be sure this starts with atoms; they are what provide
The base of this unrest. For atoms are moving on their own,
Then small formations of them, nearest them in scale, are thrown
Into agitation by unseen atomic blows,
From Lucretius: The Nature of Things translation by A. E. Stallings, Penguin Classics, 2007.
This short passage could have been a summary of Einstein’s ideas about the origin of Brownian motion. But it was written 2,000 years too early.
On the Nature of Things contains descriptions of atoms, their motion, and how they combine. Some by today’s standards are naïve; others like the Brownian motion are rather good.
However Epicureanism was not just science: it was also philosophy. That philosophy included components that did not sit well with many people. For example, the soul died with the body, and gods did not intervene in the affairs of humans. A small issue was that pleasure from sex was considered “unnecessary.”
As a result, 400 years after Lucretius died St. Jerome attempt to discredit him by claiming that he became insane after drinking a love potion and committed suicide. This story was propagated by Tennyson in a poem titled Lucretius. No evidence exists to support St. Jerome’s claim.
Perhaps if Epicurus had held different views of religion and sex, progress on humankind’s understanding of atoms and molecules would have moved much more quickly. Then the nuns at the Abbey of Saint Stephen in The Cross and the Dragon might have had molecular based medicine instead of herbs and prayers to help them nurse Hruodland back to health.
During a recent trip to India, I was reminded of the models of atom developed by Hindu philosophers at the same time as the Greek models were developed. More on that next time.
Dean Zollman is university distinguished professor of physics at Kansas State University where he has been a faculty member for more than 40 years. During his career, he has received three major awards—the National Science Foundation Director’s Award for Distinguished Teacher Scholars (2004), the Carnegie Foundation for the Advancement of Teaching Doctoral University Professor of the Year (1996), and American Association of Physics Teachers’ Robert A. Millikan Medal (1995). His present research concentrates on the teaching and learning of physics and on science teacher preparation.