Ancient atomism anticipated a genuinely granular universe

Rovelli opens his historical arc with the ancient Greek atomists, whose proposal that matter is composed of indivisible, discrete particles moving through empty space was, remarkably, philosophically closer to modern physics than the smooth, continuous view that dominated much of the intervening scientific tradition. He treats this not as a lucky coincidence but as an early instance of a recurring pattern: correct intuitions about reality's underlying discreteness can precede, by enormous stretches of time, the empirical tools needed to confirm them.

He uses this parallel to frame modern quantum theory's discovery that energy, and eventually space itself in some theories, comes in discrete units rather than smooth quantities, as a kind of vindication, however transformed, of the ancient atomist intuition. The details differ enormously, but the suspicion that reality is granular rather than infinitely smooth has very old roots.

This supports his broader argument that scientific progress isn't a simple story of accumulating certainty, but often a return to older intuitions with far more rigorous support.

Takeaway: some of physics' strangest modern discoveries about a granular universe echo philosophical intuitions that are thousands of years old.