It has been known for a long time how fast light travels. But what about the speed of darkness?
Darkness moves in a different way to light, thus travels at a different speed. But is it faster or slower than light? Or does it depend on the circumstances. Let us take a simple example, the everyday event of turning on and off a light switch.
When turning off the light the room becomes instantly dark. Thus the darkness must be at least as fast as the light to fill up the space. Now turn the light back on. The light is not there instantly it seems to take a moment longer to fill up all the space. You may also notice pockets of darkness in the corners. This shows that the light can not be moving as fast.
A better example would be watching sunrise and sunset. As the sun rises, letting light into the room the shadows get less. But the sun takes time to fill the whole room with light.  When the sun is setting the opposite is not quite true. The darkness does not take time to fill up. But fills the gaps as soon as the light leaves them. Filling up a space the light leaves as soon as it leaves it.  Unlike the light the darkness does not push into the others space but quickly flows into the space as the light leaves. This could explain why light is slower. Light has to push against the dark to take its place were as darkness flows back into the space left by moving away light.
The exact speed of darkness is very hard to calculate. But we can definitely say that darkness is a little faster than light.

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