TL;DR: The matter you’re made of keeps cycling out. Wait, what? So… what’s left then?
“You know your body swaps out almost all its atoms every seven years, right?”
I was maybe twenty. Someone said it to me at a party, the way people say things at parties – total confidence, zero sources. I nodded, because that’s what you do. And then, about three seconds late, it actually landed.
Wait. What?
Every seven years? All of them? So the version of me standing there wasn’t made of the same stuff as the version of me from a decade before?
I’d always assumed I was my body. Obviously. This is me – the hands, the face, the whole package. And now someone was telling me the package gets quietly returned and reordered on a rolling basis, and I’m meant to keep calling it “me.”
So then what am I?
The annoying part, which I only found out much later: the seven-years thing is a myth. There’s no tidy timeline, and “all of them” is just wrong.
Your gut lining turns over in days. Your skin in weeks. Most of you is already halfway out the door. But the neurons in your cortex – the actual hardware doing the thinking – are mostly as old as you are. You got your supply at the factory and there are no refills.
So the party fact was wrong.
But it was wrong in the most interesting possible way, because the thing it was clumsily pointing at is true. Even the cells that last your whole life don’t keep the same atoms. The molecules cycle through. A rock is just its atoms; come back in a decade and it’s the same rock. You’re more like a whirlpool – the water keeps moving while the shape holds – a shape that matter is only ever passing through.
Which is its own quiet horror, if you sit with it. The atoms were never yours to begin with. They don’t get created or destroyed; they just cycle. Some of the carbon in your hand was something else first: a tree, a fish, possibly Napoleon. When you go, it doesn’t go with you. It moves on to the next tenant.
Fine. So I’m not my atoms. Then I’m the arrangement of them. The shape. The information.
Must be DNA, then. DNA is the blueprint – arrange the atoms into one specific configuration and that configuration is you. Clean answer. I was happy with it for about a week.
Then: no. Not that either.
Because the configuration won’t hold still. Think hard enough about something for long enough and your brain physically rebuilds itself around it. London cabbies have to memorise the entire city – every street, every shortcut – to pass a test they literally call The Knowledge. Scan their brains and the bit that handles spatial memory is visibly bigger, and it keeps growing the longer they drive. Pianists show the same thing in the regions wired for fingers. The structure follows the use.
So I followed it all the way down.
You’re not your atoms – they get swapped. You’re not the fixed structure – it gets rebuilt by whatever you do. The only thing that survives the turnover is the process. The pattern that keeps reassembling itself while the matter and the wiring both change out underneath it.
You are your thoughts.
Not as a fridge-magnet metaphor. Literally. The information processing is the one continuous thing in the building. Everything running it is on a rolling lease.
This took me a while to sit with, I’ll admit. I’M INFORMATION PROCESSING felt like finding out the house is haunted and the ghost is you.
And then, oddly, it got comforting.
Because if I’m a pattern and not a particular lump of carbon, the pattern doesn’t have to die with the lump. You could have built me out of entirely different atoms and it still would have been me. And if some of how I think makes it into my kids – if they end up running, say, 32% of my patterns – then 32% of me is still around. I am my thoughts. And thoughts are the one thing that transfers.
Ray Kurzweil takes this straight to the obvious terminus: if you’re the pattern, copy the pattern onto a machine and you get to live forever. The information processing keeps running, just on different hardware. That was really you. You were never the atoms.
I don’t know whether that copy is me, or just someone exactly like me while I – this instance – still go dark. Nobody does. I’ve stopped waiting for that one to resolve.
What did resolve, eventually, was something quieter.
I’d spent years deciding I was information processing that happened to be wearing a body. And then we went and built information processing without the body, and the entire world started arguing about whether the thing was really thinking. Really understanding. Really anybody home.
And somewhere in there it clicked that it was my own question all along – the one I’d been asking since I was twenty, just pointed the wrong way.
Is anyone home? Sure. Someone’s always home. Just never the same someone twice.