If the speed of light is 186,00 mph, what is the speed of darkness?

Answer 1

The speed of light is 670, 616, 629 miles per hour. It's not THAT silly a question. I think that the answer is that the speed of darkness is less than or equal to the speed of light. Here is my thinking.

If you think of light as a photon then it has a limited extent in space, like the "wave packet" of light in quantum mechanics. So, you can say "darkness" is the stuff where a particular wave packet of light is not. Now, most of the darkness is not moving. But, when such a wave packet is traveling through space, the BOUNDARY of the stuff that isn't the wave packet--the "darkness" is up close to the wave packet and follows from behind on the trailing side and stays just out of the wavepacket's reach on the leading side. Since the boundary of the darkness must keep up and keep out of the way at the same speed that light travels, I say the boundary velocity of darkness behind and in front of light must also travel at the speed of light.

This is all about the speed of the boundary behind and in front of the photon. Now, darkness would also have to move out of the way perpendicularly to the photon along the sides. The odd thing here though is that the speed it would move out of the way would depend on the spread of the wavepacket. I think the extent is determined by the energy--bigger energy more concentrated wavepacket. A wavepacket that was more spread out would allow the perpendicular boundary of darkness to move out of the way and return more slowly. So the speed of the boundary of darkness in the perpendicular direction to the wavepacket's path is less than the speed of light and depends on the wavepacket's energy, slower if the wavepacket has less energy!

So darkness moves fastest behind and in front of a photon, and more slowly to the sides.

In classical mechanics, it's trickier to define the extent in space of the electromagnetic wave that makes of the photon, so it's harder to say where the darkness boundary lies. I think quantum mechanics and wave packets are the correct way to approach the speed of darkness questions.

Great question!

Also, even though wavepackets are a superposition of an infinite number of probability distributions that extend to infinity, they DO have a mean position and root-mean-square width that describes where you are most likely to find the particle and the packet DOES have a group velocity. That's the great utility of constructing a wave packet is that it does have effectively a limited extent, even though there are miniscule probabilities of finding the wavepacket away from its mean position and outside of a few root-mean-square deviations from the mean.

Answer 2

You are speaking and thinking of light and darkness in Biblical terms, but now in the 21st century, we know that there is no such thing as darkness as a separate and independent entity. Darkness is merely the absence of light, so it does not travel and has no speed.

however, if you were to ask what if i turn off a light source in a room, how fast does darkness covers the entire room? that is an answerable question. the answer is it is the amount of time it take for the last photon leaving the light source to reach the furthest wall from the light source. so darkness does not happen instantaneously like some people think.

BTW, a wave packet is a probabilistic concept, meaning that we are not actually saying that a particle like a photon is a wave in the shape of a packet moving through space. it merely describes the probability of finding the photon within a certain region of space. the reason we call it a packet is because the probability function looks like a packet, maximum at mid-point with trailing tails on both sides. so as a photon moves through space, we can only say that there's a high probability that we will find the photon at some point in space, lower probability around that point, and near zero everywhere else. so the previous response to your question is nonsensical.

Answer 3

Let A and B be two stations separated by a distance of one light year.

Let there be complete darkness around A and B.

Let a light pulse start from A which lasts only for few nano second.

As light passes from A to B, darkness precedes and follows the light pulse with the same speed.

Therefore as already stated by many, darkness spreads with the speed of light.

Answer 4

I think the speed of darkness is immediate or instantaneous. If an asteroid got in the way of the sun suddenly, not gradually like an eclipse, and a shadow fell on a certain part of the earth I believe the shadow would be an instantaneous shadow. Because the very moment the light is blocked there is an immediate darkness.

Answer 5

The speed of light is 186,000 miles per second, not hour.

Darkness has the same speed, because it is the absence of light. If there is a light source shining in your eyes, the speed of darkness is also 186,000 miles per second, as light issued by the source before it is shut off will reach you when it does, and your experience of darkness will not happen until after the last photon reaches you.

Answer 6

Darkness is the standard situation, with no light. It doesn't travel anywhere because it's always there.

Light is at least an object of some sort, and yes, its speed is 186,000 miles per second.

So, if you turn on a light to brighten a room, it travels at 186,000. Logically, when you switch the light off, ending the stream of photons, darkness will appear to 'swallow up' the light at 186,000.

Answer 7

Light travels at 186,000 miles per second..
Darkness does not travel at all unless you would
consider the darkness following a retreating
light to be also traveling.
This might be imagined however the darkness is
not really traveling behind the vanishing light.

Answer 8

Darkness doesn't have a speed because darkness isn't a "something"; it's a lack of light.

Answer 9

darkness because there is no light.

if the matter is darkness. The speed of darkness is the speed of matter.

Answer 10

I guess to make light move forward than darkness move in the other direction. So, it must be -186,000 mph.

An other question then is if light is moving forward in time, them is darkness light moving in reverse time?