You can not turn on or measure darkness. It is always there, just covered up by light, therefore it has no speed. By measuring the speed of the last photon leaving, you are actually just measuring the speed of which light leaves, not darkness. The same goes for temperature.
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[deleted]
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It amounts to the same thing. Darkness is entirely dependent on light, so it "moves" at the same speed. It's like the concept of "hole flow" in electricity - the positive charges don't move, but the flow of the negative charges relative to them can make it look like they do from the right perspective.
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[deleted]
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"the positive charges don't move, but the flow of the negative charges relative to them can make it look like they do from the right perspective." the entire point is they don't move, they are static, which means it cannot be measured. Just because it appears to move doesn't mean it moves, just like they sun. So it doesn't amount to the same thing, you are still only measuring the speed of light either way, never the speed of darkness.
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[deleted]
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"Dark" is an expression of the intensity of the light in a given volume, and we expect knowledge of changes in that intensity to travel at the speed of light.
Imagine you could switch the sun on and off at will and that you're in daylight on Earth. At t=0 when you turn the sun off, you will be unable to detect any change from your observation point on Earth. At t=~8 min, it would become dark on Earth because the last photons emitted from the sun would have finally reached you and been dissipated. Since the amount of time elapsed between turning off the sun and observing a shift to darkness exactly equals the amount of time it would take light to travel the distance between the sun and the Earth, we can say that the "speed of dark" is in fact equal to the speed of light.
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[deleted]
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You still don't get it. Darkness is static. It never moves. When you turn the switch off, the movement you are measuring is the speed at which the light is leaving, not darkness entering. So there is no "speed of dark". How is that so hard for you to understand?
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[deleted]
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I could ask you the same question. Darkness is the absence of light. Therefore the speed at which light leaves is the same as the speed at which darkness enters.
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[deleted]
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No no no no no. Darkness is ALWAYS THERE. It is STATIC. It is only covered up by light. So it doesn't leave and come back. What are shadows? Places in which light doesn't touch because of obstruction, a place of darkness. The darkness is always there but concealed whrn light is present. Darkness cannot enter because it is always there. When light leaves, you only are measuring the speed of the light. It is just like how you cannot measure the level of darkness. Absolute darkness is defined as the abscence of all light. It is the amount of light measured, not the amount of darkness. Once you remove all light, it can't get darker, however you can always add more light. This is a pretty basic concept. Darness doesn't move, it is always there, which means that it has no speed.
Dark has no speed as there is no such thing as it, darkness as it's more commonly known is defined as a lack of light, just like black, is a lack of color
Re-caption this meme
Imagine you could switch the sun on and off at will and that you're in daylight on Earth. At t=0 when you turn the sun off, you will be unable to detect any change from your observation point on Earth. At t=~8 min, it would become dark on Earth because the last photons emitted from the sun would have finally reached you and been dissipated. Since the amount of time elapsed between turning off the sun and observing a shift to darkness exactly equals the amount of time it would take light to travel the distance between the sun and the Earth, we can say that the "speed of dark" is in fact equal to the speed of light.