Source to detector

Changing what lies between

To see, you need a suitable source(torch, sun, candle) and a detector(eye).

To explore how photons can explain seeing and anything to do with lighting things up, go carefully. Photons come from the source—they’re emitted. Photons arrive at the eye—they’re absorbed. You know where photons start and end—where they are created and destroyed. But you’ve no evidence for what, if anything, happens in-between.

Collect some evidence by starting simply. Add some absorbers between the source and detector.

This effect happens. You can try it out by looking at a torch through one, then two, then three layers of black plastic bag. As you see less brightness, the number of photons detected is changed by what’s between source and detector.

So what’s in the space between source and detector affects the photons somehow. You do need to be careful because photons are part of the quantum world, something that’s only been known about for a century. The world at a quantum scale—very small SymbolEmdash is claimed to be weird, which is another way of saying that our common sense has not yet caught up with discoveries.