Dafter Question.

If the speed of light is approximately 186,282.397 miles per second, or 670,616,629.384 miles
Per hour, or almost one foot per nanosecond.
What is the speed of darkness?

My nephue would like to know.

 

the same

 

Interesting lol

Light is an electromagnet wave, darkness is a lack of light so it doesn't have a speed. You might consider the speed of darkness as the spped at which light ceases to be visible though..

Basically Darkness is a concept not an object er I think

My head hurts now

 

As light advances, darkness must recede. At exactly the same speed.

 

Well, it could be:-

http://en.wikipedia.org/wiki/StarCraft:_Speed_of_Darkness

Otherwise:- As soon as your brain no longer compreheds an input - you have it. Whatever time that may take, as per individual.

For enquiring minds that need to know:-

http://www.physicsforums.com/archive/index.php/t-101443.html

 

If that gets you,how fast does darkness travel when a Train travelling at 100mph turns off its headlight

Yeh I know the answer,no I didnt have to look it up,no I'm not smart I just love this stuff

 

Doppler effect for darkness anyone?

 

er... X-rays, Gamma rays, radio waves, microwaves are electromagnetic waves that are not visible light but also travel at the speed of light. The definition of darkness has been adequately stated, all sorts of things travel in the darkness.

 

Short answer: Since "dark" is the absence of light, we can assume that once a source has been extinguished, the end of the electromagnetic wave will reach the observer traveling at the speed of light.

Long answer:

Light cones! http://en.wikipedia.org/wiki/Light_cone
You can model this using a light cone, where at the origin you have an event (in this case the event is the light source being extinguished), and at a line of, say, x=50, z=0, you have the position of the observer. The y axis is time.

The cone will expand where the angle of it's tip is equal to the speed of light. This is how an "event" is observed. Once your location intersects the cone you will observe the event.

Since the gradient of the cone is equal to the speed of light, always, then we can assume that observing any event in the electromagnetic spectrum (such as an alteration in light) will be observed at the same time regardless of it's nature.

But what if you had a mirror behind you?

In this case, when you receive the last photon (or end of the wave if you prefer) there will still be a stream of photons behind you which haven't been reflected by the mirror. These will then hit the mirror and reflect back to your position. And as such darkness will take longer to "reach" you. This is, of course, assuming that you take exactly half of the photons which reach you at any one point. You could be, in this case, a beam splitter (a perfect one).

If you averaged this out you'd end up with a speed of "darkness" which is slower than that of light! In this case your equation would be:

Let :
distance from observer to source = x
distance from observer to mirror = j
speed of light = c

speed of "darkness" = (x / c) - (2*j / c)

This only works in the linear case, and where your observing the output of a beam splitter directly in between the light source and the mirror.

You can make this as complicated as you want, really

It's also possible to model "sound" cones as well, but they are much less frequently used as it's usually more complicated than can be modeled with a cone, and there are other better ways of representing the propogation of pressure waves which can take into account reverberations and such.

 

You spelt once wrong

 

And linear.

Nobody's perfect

 

Looks fine to me

 

I am very impressed by Goldfish's reply . . . nice indeed!

But, seeing as I am a simple soul - here is my take on the question: The speed of dark is relative

One time long ago, I became lost while hunting in a national forest (in the largest tract of public land east of the Mississippi river). Well, it seemed the speed of dark was pretty damn zippy that day!

Cut to my wedding day when I had to wait for darkness to fall till all the guests left and I could get on with the honeymoon - it seemed dark took it's damn sweet time to arrive . . .

Einstien was right!

 

Sheesh if you guys are finished will you please turn out the dang LIGHT

 

The speed of light is 670616629.13 mp/h, and both of yours sources are correct because.

86,282.397 miles per second x 60 = ?
? x 60 = 670,616,629.384 miles Per hour

Because:

Seconds x 60 = minutes
minutes x 60 = hours

So all i did was x the miles per second by 60 to gt miles per minute then by 60 again to get miles per hour.

Well, darkness is simply the absence of light. Therefore 'darkness' will take the same time to reach something (following extinguishing of a light source) as light would (following illuminating of the source).

Does that Help ?

 

There is much truth in this!

I once read a book called Mr God, this is Anna, by Flynn, and Anna has some interesting theories about this, and she actually demonstrates that darkness (or in this case shadows) move faster than light!

If it was my nephew who asked this, I would give him an other example on how speed is relative:

If it takes a week to walk a fortnight,
how long will it take a flee to cross a treacle barrel?

If you can't figure out the right answer, I'll help you a little later!

 

And here I thought that the Speed of Darkenss was actually how fast the evil kung fu bad guys moved.


sheesh... another childhood dream up in smoke... LOL

~c

 

the speed of darkness is relative to the absence of light. therefor the rate at which the light diminishes (NOT the speed of light itself) is the relative factor. if light diminishes slowly, than darkness falls slowly. if light is extinguished instantly, the dark becomes instant. i experience this phenomena every night.

 

. . . Well, I give up . . . except maybe half as long as it should?

I know I am missing the point, but my old brain just can't wrap itself around it

 

Heres a nice little film on light and time,too basic for Goldfish I watched it last night and enjoyed it

http://video.google.com/videoplay?docid=-5896048467372201322&q=FIRST+TIME+MACHINE&hl=en

 

You really don't know?

Are you stuck...?

 

I must confess to my shame that I do not know.

I'm gonna feel silly, aren't I . . .

 

It doesn't take any time at all, because it doesn't even bother trying

 

Are you sure you don't know? You are completely stuck?

 

...........

 

Shesh, you don't have to spell it out THAT loud!

http://members.chello.se/solange/smileys/Rotfl.gif

 

lol - actually I think Goldfish had to, seeing as how I was too dense to get it . . .

It seems so simple now . . .