If photons bounce off of surfaces (get reflected), why does it immediately go dark after we switch off the lights?
In: Physics
Because first of all surfaces do not reflect 100% of light. Secondly, light is FAST. Light is moving at 299.792.458 meters per second.
Now why is that important?
Because the faster something is, the more frequently it could bounce right?
For simplicity imagine photons as a collection of balls, now imagine them to be in a room where the longest distance they could travel before bouncing was 3 meters. This would mean they could do at least roughly 100.000 bounces per second.
Ok so it bounces often, now what?
Imagine the surface could reflect 99% of light:
before the bounce intensity is 1.
1 bounce -> 0.99
2 bounces -> 0.99^2 = 0.9801
3 bounces -> 0.99^3 = 0.970299
…
10. bounces -> 0.99^3 = 0.904382075
…
1000 bounces -> 0.99^1000 = 0.00004317124
So after 1000 bounces that reflect 99% of the light, only 0.004% of the light is left.
But the light is able to do 100.000 bounces per second, which means it only needs 10 milliseconds to do the 1000 bounces. That is the timespan a single frame is shown on a 100hz monitor!
On top of that, you do only ever see light that hits your eyes in the first place, this not only reduces the amount of possible light to see, but you yourself remove light with your eyes because the light you see doesn’t bounce back!
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