A red tomato. Seen this color dozens of times, never noticing anything special. It just is — solid, rich, confident. Everything matches: the word “red,” the feeling, the thing on the table. Seems like there’s no question.

But if I stop, that confidence slips away. Where is red, really? Inside the tomato? It’s just molecules reflecting a certain wavelength. In the air between me and the table? Photons flying — no color in them. Even on the retina it’s still just electricity and biochemistry.

I start to wonder: when exactly does red begin? Looks like it’s right in my head. I always thought color was a property of the world itself, not just my nervous system.

Outside my head, there are no colors. Only wavelengths and streams of particles — numbers for instruments or graphs for physicists. It only becomes “red” after the brain puts the signals together into something familiar and whole.

There’s a weird kind of hurt — so many years I was sure color was objective, and now it turns out red only lives inside my skull.

The awkwardness grows. I call it “red” because that’s what I was taught. But can I be sure I feel the same thing as someone else? We both look at the tomato and nod: yeah, it’s red. But inside us might be different worlds — and we’ll never know.

How to check? Philosophy even has a word for this puzzle — qualia: the subjective quality of experience that’s totally locked away from the outside. My red could be your green; we just agreed to call it the same.

Another weird thought pops up. If I didn’t have the word “red,” would I even have this experience? Or would it just be a flash of signal without a name — until language gives it a place among other feelings? The story about the Pirahã people in the Amazon comes to mind: they don’t have words for colors, and shades either stack up differently or vanish from their perception.

Sometimes you meet people with four types of cones in their eyes — tetrachromats see shades of red I can’t even imagine. Their experience is so much wider than language that there’s a gulf between our worlds.

The longer I think about vision and how the brain builds the world’s picture from a mess of signals — the further away “red” drifts. The feeling dissolves among numbers and neural patterns; only the question remains.

When I eat a tomato and think about its redness — who owns that color? Me? Language? The outside world?

I don’t know.
But now at least I see exactly where the not-knowing begins.