Ever heard of an old soul? According to one theory making the rounds among physicists, virtually every electron in your body may be more than a googol years old (10 to the 125th power), much older than the universe itself, if I understand the premise correctly.
A fascinating article at io9 by Alasdair Wilkins imagines that every electron in the universe is a single particle:
As Wheeler pointed out, each electron traces out a unique path through spacetime, which is its world line. He simply connected all the forward-traveling electrons and backwards-traveling positrons into a single gigantic world line, imagining a particle tracing its way back and forth through the history of the universe to become every electron and positron we had ever observed. And that was why all electrons were indistinguishable.
The implications of this would be absolutely tremendous. Current estimates suggest there’s about 1080 atoms in the observable universe, so let’s use that same figure for the number of electrons. (Actually, since the vast majority of those are one-electron hydrogen atoms anyway, that isn’t much of a stretch.) The universe is already nearly 14 billion years old, but it will last far, far longer than that, although the ultimate age of the universe depends on which theory of its final fate you subscribe to.
Since we’re really only going for a rough estimate anyway, let’s just use 4.6*1026 years, which is the lower limit for the lifetime of an electron before it decays (assuming it actually decays, which isn’t a certainty). So then, if the one electron universe is correct, that single particle has traveled through the universe 1080 times, with each journey taking 460 septillion years, and you can double that for all its return trips as a backwards-going positron.
That means, by the end of its journey, the electron is 2*4.6*1024*1080 years old, or just about 10105 years old. That’s ten-thousand googol years old. That also means that 99.99% of the electrons in your body, and indeed everywhere in the universe, have already been traveling for over a googol years…assuming this is true, of course. I don’t know about you, but I suddenly feel weirdly ancient.
It’s going too far to call the idea of a one electron universe a full-fledged theory, or really anything close too it – it’s more of a gloriously unconventional thought experiment. But that doesn’t change the fact that, from a strictly theoretical perspective, there’s absolutely nothing wrong with it. Sure, your intuition probably tells you that this is very, very unlikely, but classical world intuition doesn’t mean anything in the quantum world.
The article goes on to explain some very good reasons why the One Electron Theory isn’t very likely.
Likely or not, I can’t say from the physicist’s perspective, but I do feel that the whole existence of the universe at all strikes me as pretty damn unlikely.