None of the atoms reading this sentence will be at your funeral.
In the 1940s, a physicist named Paul Aebersold, later Oak Ridge’s Mr. Radioisotope, fed people radioactive isotopes (it was a more relaxed era) and watched where the atoms went.
The answer: everywhere, briefly. His estimate, which he never actually measured, was that about 98% of the atoms in a human body are swapped out within a year. The gut lining goes in days. The skeleton, which feels like the permanent part, cycles on the order of a decade.
Whatever you are, you are not your matter. Your matter barely stays the weekend.
Fine, the bricks change, but the building stands. Except the building doesn’t stand either – it’s being continuously demolished and rebuilt to a drifting blueprint, connections pruned and grown all night, every night.
There is no vault-room where the real you sits untouched while the maintenance crews work around it. It’s maintenance crews all the way down.
So what’s left to be?
Watch a whirlpool below a weir. The water in it is never the same water twice, and the shape holds anyway. The whirlpool is what the water is doing there.
Your atoms are just passing through, at a rate that should terrify you. You’re what they’re doing while they pass.
Which changes the tense of being alive.
A statue exists. You occur.
The person who went to sleep in your bed last night was a slightly different arrangement of matter than the one reading this – close enough to answer to your name, different enough that “same” is a courtesy the ancient gods and new ones extend daily and could, in principle, decline.
I find this either horrifying or consoling depending on the hour.
Horrifying by night: nothing about me persists.
Consoling by day: nothing about me is stuck.
The river brings new water whether you asked for it or not.
The whirlpool never holds the water… only the shape. That turns out to be the whole job.
And that turns out to be you.
Related: You Are Your Thoughts – the original, longer take.
Sources: TIME, The Fleeting Flesh, 1954 · Sender & Milo, Nature Medicine, 2021 · Surgeon General, Bone Health · de Vivo et al., Science, 2017
I came for a physics lesson and left with an existential crisis. 10/10, would get atomically replaced again.
"A statue exists. You occur". Stunning!