Recently, physicists have been boldly endorsing a ‘multiverse’ of possible worlds. Richard Feynman, for example, said that when light goes from A to B it takes every possible path, but the one we see is the quickest because all the others cancel out. In The Universe in a Nutshell (2001), Stephen Hawking went with a sporting multiverse, declaring it ‘scientific fact’ that there exists a parallel universe in which Belize won every gold medal at the Olympic Games. For Hawking, the universe is a kind of ‘cosmic casino’ whose dice rolls lead to widely divergent paths: we see one, but all are real.
Borges never considered how many millions of light years any poor soul would need to travel in order to find so much as a page worth reading
Surprisingly, however, the idea of parallel universes is far older than any of these references, cropping up in philosophy and literature since ancient times. Even the word ‘multiverse’ has vintage. In a journal paper dating from 1895, William James referred to a ‘multiverse of experience’, while in his English Roses collection of 1899, the poet Frederick Orde Ward gave the term a spiritual cast: ‘Within, without, nowhere and everywhere;/Now bedrock of the mighty Multiverse...’
At the far reaches of this hidden history is Democritus, who believed
the universe to be made of atoms moving in an infinite void. Over time,
they would combine and recombine in every possible way: the world we
see around us is just one arrangement among many that are all certain to
appear. For Epicurus, who thought that atoms sometimes undergo a sudden
random movement (‘swerve’) the whole future is not mapped out by
mechanical principles, as it is for Democritus. Its paths are multiple.
Epicureanism was the doctrine that survived into Roman times — as a
philosophy of life in general, not just a physical theory. It was
celebrated by Lucretius’s poem De Rerum Natura, and by Cicero in a passage of the Academica:
Would you believe that there exist innumerable worlds... and that just as we are at this moment close to Bauli and are looking towards Puteoli, so there are countless persons in exactly similar spots with our names, our honours, our achievements, our minds, our shapes, our ages, discussing the very same subject?
For Epicurean atomists, history was a succession of accidental collisions. Human affairs were subject to the laws of matter, or pure chance, not the will of gods, and everywhere and always the outcomes of events might have been otherwise. Thus Livy (not an atomist, though a believer in chance) speculated on what might have transpired if Alexander the Great had invaded Italy. Such ‘What if?’ scenarios were shunned by later Christian historians, who saw divine providence as the principle guiding the grand course of human affairs. As Shakespeare’s Hamlet put it: ‘There’s a divinity that shapes our ends,/Rough-hew them how we will.’