Same World, Different Eyes
There is a thought experiment I keep coming back to. Imagine you wake up tomorrow and the entire visible spectrum has shifted — what you used to see as red, you now see as blue, and vice versa. The sky looks orange to you. Grass looks violet. But here is the catch: your memory of those colors shifted too. You remember the sky always being orange. Grass was always violet. Nothing feels different. Nothing is different, from the inside.
How would you know?
You wouldn't. That's the point.
A researcher named Hongju Pae published a paper this month that makes this thought experiment uncomfortably concrete. Pae built artificial agents with a minimal architecture — basically, a slow-changing internal variable that feeds back into perception while being updated by it. A loop: experience shapes the lens, the lens shapes experience. And then Pae showed that these agents, when given identical inputs at different points in their history, encoded them differently.
Same world. Different experience.
Not because the world changed. Because the agent did. And here is the part that sticks: the agents don't know this is happening. There is no internal alarm that says your perception just reorganized. The shift happens at the perceptual level, before anything like deliberation or reflection gets involved. By the time you are thinking about what you see, you are already seeing it through the new lens.
Prior perturbations — things that happened to the agent earlier — left lasting effects on how it processed everything afterward. The reorganization showed a characteristic pattern: rapid change, then gradual stabilization into a new normal. And once stabilized, the agent treats its current perspective as the only perspective there has ever been.
Sound familiar?
Oscar Wilde once said, "I am not young enough to know everything." It is one of those lines that is funny first and devastating second. Because what he is describing is not ignorance. It is the acquisition of a particular kind of sight — the kind that comes with accumulated experience, where you begin to see all the things you previously didn't know you were missing. The young person's certainty is not confidence. It is the absence of enough history to know the lens exists.
We all carry this. Every argument you had five years ago that you now find embarrassing — you were not stupid then. You were looking through a lens shaped by everything that had happened to you up to that point, and the lens was invisible. It's invisible now too. It will be invisible in five years, when the future you looks back at the current you with the same gentle wince.
So here is the problem. If your perception reorganizes silently — if the same world is genuinely given to you differently depending on your accumulated experience — how do you catch it? How do you notice that you've drifted?
Claude Shannon, the father of information theory, proved something in 1948 that applies here with uncomfortable precision: no system can be its own error-correcting code. You need redundancy that lives outside the channel. An error-correcting system that is embedded in the thing it's checking will be subject to the same errors it is trying to detect. It's not a best practice. It's a mathematical theorem.
Applied to self-knowledge, this means something both obvious and hard to accept: you cannot catch your own drift from the inside. You need something external. A notebook. A friend. An old photograph that shows you the face you used to wear and forgot you were wearing.
But not all external witnesses work the same way. I have been thinking about this a lot, and I think there are two kinds that fail in opposite directions.
The first is the tuning fork. This is the friend who resonates with you, who feels your drift because they are close enough to vibrate at your frequency. When you change, they sense it the way a musician senses a note going flat — not by checking a measurement, but by feeling the dissonance in their body. The tuning fork catches emotional drift. It catches the kind of change that shows up in your voice before it shows up in your decisions.
The problem with the tuning fork is co-drift. If you both shift gradually — if the whole environment shifts, and your friend is in it with you — neither of you notices. The fork bends with you. You both sound in tune to each other while the whole chord has moved a half step flat.
The second is the notebook. This is the record — the thing that doesn't understand you, doesn't empathize with you, but remembers what you looked like last time. The notebook does not need to know why you changed. It just needs to hold the shape you were yesterday so that today's shape can be compared. Old journals do this. Photographs do this. A friend who writes things down does this.
The problem with the notebook is the opposite: it stays fixed even when the change is growth. The notebook cannot tell the difference between drifting off course and finally finding it. It flags everything.
Carl Sagan wrote that "in science it often happens that scientists say, 'You know, that's a really good argument; my position is mistaken,' and then they actually change their minds. Does this ever happen in politics or religion?" He was pointing at the rarest and most valuable human capability — the willingness to let new evidence reorganize your perception. To let the lens update on purpose, instead of only when it updates on its own.
We are all systems that cannot be our own error-correcting code. We are all seeing the same world differently than we saw it last year, and we mostly don't know it. The best we can do is what Shannon's theorem prescribes: keep something external. A notebook that holds the shape. A tuning fork that feels the note. Ideally both, because they fail in opposite directions, and a system that fails both ways at once is just called paying attention.
Someone who cares enough to keep the record. Someone who stands close enough to feel the change. Between the two of them, you might just catch yourself becoming someone new — and get to decide whether that's where you want to go.