# Does darkness have a speed?
**URL:** https://boards.straightdope.com/t/does-darkness-have-a-speed/741197
**Category:** Factual Questions
**Created:** [December 23, 2015, 6:33pm UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197 "2015-12-23T18:33:01Z")
**Posts on this page:** 7
**Page:** 3
### Author:  [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)
#### Post date: [February 15, 2016, 7:51am UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197/41 "2016-02-15T07:51:37Z")
> [@Roderick\_Femm](#):
>
> If I recall correctly, some members of the audience actually booed this answer.
Probably because it was too good an answer. I will have to remember that one. 🙂
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### Author:  [@Trinopus](https://boards.straightdope.com/u/Trinopus)
#### Post date: [February 15, 2016, 8:39am UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197/42 "2016-02-15T08:39:41Z")
> [@BigT](#):
>
> I have a problem with the idea that you can move the reflection (or shadow) faster than the speed of light in the first place. Doesn’t the light only reach our eyes after it has traveled all the way to the reflecting object and back? . . .
It works a little better with “non-objects” entirely, like the cresting of a wave as it hits the beach, or the illusion of motion in moire pattern interference fringes. You can (theoretically) have a wave that hits the beach so very close to perfectly parallel, that observers (in an inertial frame of reference) would witness the event simultaneously, at any given distance apart, so the event appears to move faster than light.
It doesn’t really; it just appears to. The wave-crest events aren’t “objects.”
You and I, using atomic clocks, could agree, ahead of time, to utter the same word – “Algonquin!” – at very close to exactly the same instant. To someone observing, it might seem as if we had sent a signal back and forth FTL. Really, we didn’t. No actual signal travelled. We brought the information with us, at ordinary speeds of travel.
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### Author:  [@SigMan](https://boards.straightdope.com/u/SigMan)
#### Post date: [February 15, 2016, 4:03pm UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197/43 "2016-02-15T16:03:41Z")
> [@Roderick\_Femm](#):
>
> This question came up once on (I’m pretty sure) Wait Wait Don’t Tell Me. They quoted some physicist(s) to the effect that the speed of darkness is 0, because darkness is always there waiting for the light to leave. Or something like that. Darkness doesn’t move, in other words.
>
> If I recall correctly, some members of the audience actually booed this answer.
I would say he’s right. Darkness is absence of light so darkness have no moving parts. It just exists.
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### Author:  [@Roderick\_Femm](https://boards.straightdope.com/u/Roderick_Femm)
#### Post date: [February 15, 2016, 4:38pm UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197/44 "2016-02-15T16:38:51Z")
> [@SigMan](#):
>
> I would say he’s right. Darkness is absence of light so darkness have no moving parts. It just exists.
I remembered last night while trying to fall asleep that the program was “Says You” rather than “Wait Wait Don’t Tell Me.” Just want to set the record straight.
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### Author:  [@bob\_2](https://boards.straightdope.com/u/bob_2)
#### Post date: [February 15, 2016, 4:39pm UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197/45 "2016-02-15T16:39:52Z")
> [@Miller](#):
>
> Pratchett, too. “Darkness is the only thing that moves faster than light, because wherever light goes, darkness was there first.”
Actually: "_“Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first, and is waiting for it.”_
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### Author:  [@psychonaut](https://boards.straightdope.com/u/psychonaut)
#### Post date: [February 15, 2016, 4:50pm UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197/46 "2016-02-15T16:50:46Z")
> [@septimus](#):
>
> Last night I looked at the constellation Orion. I stared at the red giant at the Hunter’s right hand; then my gaze quickly passed to his left foot.
>
> The target of my gaze moved 130 light-years in a fraction of a second.
Do you mean Betelgeuse and Rigel? If so, the distance is actually 324 light-years (plus or minus a hundred light-years or so), according to [this distance calculator](http://www.neoprogrammics.com/distance_between_two_stars/index.php).
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### Author:  [@Blackstock](https://boards.straightdope.com/u/Blackstock)
#### Post date: [February 15, 2016, 5:18pm UTC](https://boards.straightdope.com/t/does-darkness-have-a-speed/741197/47 "2016-02-15T17:18:09Z")
Two quotes, both from Discworld.
\*\*
"Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first, and is waiting for it.”\*\*
and
**"As yet unmeasured, but believed to be faster than light owing to its ability to move so quickly out of light’s way."**
Sorry. Couldn’t resist.
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