When you close both eyes you see black, but when you close one you don’t see half black.
When you close both eyes, the photoreceptors in your eyes are not receiving any light, so you perceive blackness. When you close one eye, the other eye is still receiving light and sending signals to your brain, so you do not see half black, but rather the image that your open eye is seeing.
It’s also worth noting that the perception of black is not simply a result of the absence of light, but is actually an active process that occurs in your brain. The cells in your retina that detect light and send signals to your brain are called rods and cones. When they are not stimulated by light, they send a signal to your brain that is interpreted as blackness.
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That’s really interesting, Andrew. I didn’t know that.
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