University of Denver
The modern idea that nature is discrete originated in Ancient Greek atomism. Leucippus, Democritus and Epicurus all argued that nature was composed of what they called ἄτομος (átomos) or ‘indivisible individuals’. Nature was, for them, the totality of discrete atoms in motion. There was no creator god, no immortality of the soul, and nothing static (except for the immutable internal nature of the atoms themselves). Nature was atomic matter in motion and complex composition – no more, no less.
Despite its historical influence, however, atomism was eventually all but wiped out by Platonism, Aristotelianism and the Christian tradition that followed throughout the Middle Ages. Plato told his followers to destroy Democritus’ books whenever they found them, and later the Christian tradition made good on this demand. Today, nothing but a few short letters from Epicurus remain.
Atomism was not finished, however. It reemerged in 1417, when an Italian book-hunter named Poggio Bracciolini discovered a copy of an ancient poem in a remote monastery: De Rerum Natura (On the Nature of Things), written by Lucretius (c. 99-55 BCE), a Roman poet heavily influenced by Epicurus. This book-length philosophical poem in epic verse puts forward the most detailed and systematic account of ancient materialism that we’ve been fortunate enough to inherit. In it, Lucretius advances a breathtakingly bold theory on foundational issues in everything from physics to ethics, aesthetics, history, meteorology and religion. Against the wishes and best efforts of the Christian church, Bracciolini managed to get it into print, and it soon circulated across Europe.
This book was one of the most important sources of inspiration for the scientific revolution of the 16th and 17th centuries. Nearly every Renaissance and Enlightenment intellectual read it and became an atomist to some degree (they often made allowances for God and the soul). Indeed, this is the reason why, to make a long and important story very short, science and philosophy even today still tend to look for and assume a fundamental discreteness in nature. Thanks in no small part to Lucretius’ influence, the search for discreteness became part of our historical DNA. The interpretive method and orientation of modern science in the West literally owe their philosophical foundations to ancient atomism via Lucretius’ little book on nature. Lucretius, as Stephen Greenblatt says in his book The Swerve (2011), is ‘how the world became modern’.
There is a problem, however. If this story is true, then modern Western thought is based on a complete misreading of Lucretius’ poem. It was not a wilful misreading, of course, but one in which readers committed the simple error of projecting what little they knew second-hand about Greek atomism (mostly from the testimonia of its enemies) onto Lucretius’ text. They assumed a closer relationship between Lucretius’ work and that of his predecessors than actually exists. Crucially, they inserted the words ‘atom’ and ‘particle’ into the translated text, even though Lucretius never used them. Not even once! A rather odd omission for a so-called ‘atomist’ to make, no? Lucretius could easily have used the Latin words atomus (smallest particle) or particula (particle), but he went out of his way not to. Despite his best efforts, however, the two very different Latin terms he did use, corpora(matters) and rerum (things), were routinely translated and interpreted as synonymous with discrete ‘atoms’.
Further, the moderns either translated out or ignored altogether the nearly ubiquitous language of continuum and folding used throughout his book, in phrases such as ‘solida primordia simplicitate’ (simplex continuum). As a rare breed of scholar interested in both classical texts and quantum physics, the existence of this material continuum in the original Latin struck me quite profoundly. I have tried to show all of this in my recent translation and commentary, Lucretius I: An Ontology of Motion (2018), but here is the punchline: this simple but systematic and ubiquitous interpretive error constitutes what might well be the single biggest mistake in the history of modern science and philosophy.
This mistake sent modern science and philosophy on a 500-year quest for what Sean Carroll in his 2012 book called the ‘particle at the end of the universe’. It gave birth to the laudable virtues of various naturalisms and materialisms, but also to less praiseworthy mechanistic reductionisms, patriarchal rationalisms, and the overt domination of nature by humans, none of which can be found in Lucretius’ original Latin writings. What’s more, even when confronted with apparently continuous phenomena such as gravity, electric and magnetic fields, and eventually space-time, Isaac Newton, James Maxwell and even Albert Einstein fell back on the idea of an atomistic ‘aether’ to explain them. All the way back to the ancients, aether was thought to be a subtle fluid-like substance composed of insensibly tiny particles. Today, we no longer believe in the aether or read Lucretius as an authoritative scientific text. Yet in our own way, we still confront the same problem of continuity vs discreteness originally bequeathed to us by the moderns: in quantum physics.
Theoretical physics today is at a critical turning point. General relativity and quantum field theory are the two biggest parts of what physicists now call ‘the standard model’, which has enjoyed incredible predictive success. The problem, however, is that they have not yet been unified as two aspects of one overarching theory. Most physicists think that such unification is only a matter of time, even though the current theoretical frontrunners (string theory and loop quantum gravity) have yet to produce experimental confirmations.
Quantum gravity is of enormous importance. According to its proponents, it stands poised to show the world that the ultimate fabric of nature (space-time) is not continuous at all, but granular, and fundamentally discrete. The atomist legacy might finally be secured, despite its origins in an interpretive error.
There is just one nagging problem: quantum field theory claims that all discrete quanta of energy (particles) are merely the excitations or fluctuations in completely continuous quantum fields. Fields are not fundamentally granular. For quantum field theory, everything might be made of granules, but all granules are made of folded-up continuous fields that we simply measure as granular. This is what physicists call ‘perturbation theory’: the discrete measure of that which is infinitely continuous and so ‘perturbs one’s complete discrete measurement’, as Frank Close puts it in The Infinity Puzzle (2011). Physicists also have a name for the sub-granular movement of this continuous field: ‘vacuum fluctuations’. Quantum fields are nothing but matter in constant motion (energy and momentum). They are therefore never ‘nothing’, but more like a completely positive void (the flux of the vacuum itself) or an undulating ocean (appropriately called ‘the Dirac sea’) in which all discrete things are its folded-up bubbles washed ashore, as Carlo Rovelli puts it in Reality Is Not What it Seems (2016). Discrete particles, in other words, are folds in continuous fields.
The answer to the central question at the heart of modern science, ‘Is nature continuous or discrete?’ is as radical as it is simple. Space-time is not continuous because it is made of quantum granules, but quantum granules are not discrete because they are folds of infinitely continuous vibrating fields. Nature is thus not simply continuous, but an enfolded continuum.
This brings us right back to Lucretius and our original error. Working at once within and against the atomist tradition, Lucretius put forward the first materialist philosophy of an infinitely continuous nature in constant flux and motion. Things, for Lucretius, are nothing but folds (duplex), pleats (plex), bubbles or pores (foramina) in a single continuous fabric (textum) woven by its own undulations. Nature is infinitely turbulent or perturbing, but it also washes ashore, like the birth of Venus, in meta-stable forms – as Lucretius writes in the opening lines of De Rerum Natura: ‘Without you [Venus] nothing emerges into the sunlit shores of light.’ It has taken 2,000 years, but perhaps Lucretius has finally become our contemporary.