How fast is darkness?

[Thanatos]

As fast as light? Faster? Imagine a shadow puppet. Darkness has a speed that is directly related to how fast you wiggle your fingers. Imagine a bigger shadow puppet using a screen that's a bit bigger, like the moon and some sort of giant laser projector that would probably melt my hands, but continue with the thought experiment anyway. I'll wear gloves for this shadow puppet session.

If I flicked my fingers would it be possible to make a wave of darkness travel faster than the speed of light?

[Ajdub18]

Well in your example darkness is only relative to the light you block out. You would perceive darkness as the part of light that you blocked. So, in reality you would be watching the light reflecting around your fingers. Meaning you would only be seeing the speed of light not the speed of darkness.

But it is an interesting question. How fast is the darkness of infinite space? When you look at a distant star the light could take millions of years to reach you. So how fast does the darkness around that star reach you?

[Jinei]

Quote by: Thanatos As fast as light? Faster? Imagine a shadow puppet. Darkness has a speed that is directly related to how fast you wiggle your fingers. Imagine a bigger shadow puppet using a screen that's a bit bigger, like the moon and some sort of giant laser projector that would probably melt my hands, but continue with the thought experiment anyway. I'll wear gloves for this shadow puppet session. If I flicked my fingers would it be possible to make a wave of darkness travel faster than the speed of light?

The wave of darkness you're talking about is a shadow. If we define a shadow as the darkness resulting from the obstruction of a light source, then a shadow may only travel at the speed of light. When you put your hand in the way of a laser, the residual light beam would still be travelling toward the moon (in your example), so it would take about a second for the last of the beam to reach the moon. Since the last of the beam is followed by shadow, the shadow will get there in about a second.

[SoylentGreen]

No matter how fast light travels, darkness is always there first.

[Gods_Mercenary]

I'd say that since darkness can travel as fast as the light is disappearing, they have equal speeds.

[wyoguy]

Quote by: Thanatos As fast as light? Faster? Imagine a shadow puppet. Darkness has a speed that is directly related to how fast you wiggle your fingers. Imagine a bigger shadow puppet using a screen that's a bit bigger, like the moon and some sort of giant laser projector that would probably melt my hands, but continue with the thought experiment anyway. I'll wear gloves for this shadow puppet session. If I flicked my fingers would it be possible to make a wave of darkness travel faster than the speed of light?

Interesting....

*Stupid personal note* -- first time I read through your OP, I thought it said "licked" my fingers. I was sure you'd gone over the edge. lol

[yanieh]

Newton's Law of Motion applies... "Every Action has an Equal and Opposite Reaction". Light and Darkness are two directly opposite things. The absence of the first means the presence of the second. How fast? Just as how fast the other one fades.

[Jinei]

Quote by: SoylentGreen No matter how fast light travels, darkness is always there first.

Well that would be true for darkness, but not for a shadow. Besides, darkness doesn't travel.

[Thanatos]

Quote by: Jinei The wave of darkness you're talking about is a shadow. If we define a shadow as the darkness resulting from the obstruction of a light source, then a shadow may only travel at the speed of light. When you put your hand in the way of a laser, the residual light beam would still be travelling toward the moon (in your example), so it would take about a second for the last of the beam to reach the moon. Since the last of the beam is followed by shadow, the shadow will get there in about a second.

So it will take a second before it gets there but once it gets there the wave of shadow will appear to move across the moon faster than the speed of light?

[Tycoon]

So it will take a second before it gets there but once it gets there the wave of shadow will appear to move across the moon faster than the speed of light?

No, at exactly the speed of light. Darkness is the absence of light. Before you put your hand in front of the light beam there was light traveling to the moon at the speed of light. When you put your hand in front of the light beam you stopped the flow of light, but there was already light on its way inbetween the source and the moon, traveling at the speed of light. The shadow will not exist until all this light reaches the moon.

[Dr_Acula]

Quote by: Thanatos As fast as light? Faster? Imagine a shadow puppet. Darkness has a speed that is directly related to how fast you wiggle your fingers. Imagine a bigger shadow puppet using a screen that's a bit bigger, like the moon and some sort of giant laser projector that would probably melt my hands, but continue with the thought experiment anyway. I'll wear gloves for this shadow puppet session. If I flicked my fingers would it be possible to make a wave of darkness travel faster than the speed of light?

Darkness doesn't travel.

Though you could think of a donut: you move it around. How fast does the hole in it move? As fast as the donut.

[Darebirth]

Quote by: Thanatos As fast as light? Faster? Imagine a shadow puppet. Darkness has a speed that is directly related to how fast you wiggle your fingers. Imagine a bigger shadow puppet using a screen that's a bit bigger, like the moon and some sort of giant laser projector that would probably melt my hands, but continue with the thought experiment anyway. I'll wear gloves for this shadow puppet session. If I flicked my fingers would it be possible to make a wave of darkness travel faster than the speed of light?

Well, scientifically speaking, darkness is just the absense of light. Picture for a moment the colors white and black. Black is the presence of all color (or all colors blended together) while white is the absence of all color. In this way, white is not necessarily a color, but is rather the absence of said color. Atheism isn't a religion, it is the absence of religion. Space is the absence of matter.

Darkness doesn't necessarily travel because it is not made of anything. Light is of course made of waves, and any place where those waves are not present will have darkness.

[Jinei]

Quote by: Thanatos So it will take a second before it gets there but once it gets there the wave of shadow will appear to move across the moon faster than the speed of light?

Nope. Any change in what you're projecting will take one second to get to the moon. If you change your hand from a bunny rabit to a dinosaur, the change will take about a second, all the while these changes travelling at the speed of light.

Quote by: Darebirth Well, scientifically speaking, darkness is just the absense of light. Picture for a moment the colors white and black. Black is the presence of all color (or all colors blended together) while white is the absence of all color. In this way, white is not necessarily a color, but is rather the absence of said color. Atheism isn't a religion, it is the absence of religion. Space is the absence of matter. Darkness doesn't necessarily travel because it is not made of anything. Light is of course made of waves, and any place where those waves are not present will have darkness.

Yeah, that's why I hastened to make the distinction in my first and second posts about "darkness" and "shadow."

[Eraldo Coil]

I'd say that since darkness can travel as fast as the light is disappearing, they have equal speeds.

Going to have to agree with Mercenary on this one. Say if it's really dark in your basement. I'm talking pitch black, if you turn your flashlight on the room illuminates, as soon as you turn it off, the room returns to it's original state just as quickly.

[adam10312]

There's no such thing as darkness. It is just a term used to explain the absence of light. It doesn't move. Light moves; where it no longer is, we call darkness. This is just easier than saying no-light-area. Once you understand this, you realize that "darkness" can only occur as fast as light can move. Or, that light can only move as fast as light can move.

[GG04]

exactly right. Darkness does not exist. Therefore it can't be measured. And it certainly can't move faster than the speed of light.