7
$\begingroup$

I've been looking around, and can't find a solid answer. Many websites say darkness is the speed of light due to the fact it is the absence of light, but other sources say otherwise, that in some cases darkness is actually faster in some cases. Could someone clarify this for me?

$\endgroup$

closed as unclear what you're asking by James K, called2voyage Jan 14 '17 at 6:09

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ astro.uni-bonn.de/~dfischer/dark_sucker_2.html is a humorous take on the subject $\endgroup$ – barrycarter Dec 20 '15 at 14:56
  • $\begingroup$ Darkness is not "a thing". It's just a linguistic shorthand for a type of absence. How fast does the absence of a thing occur? $\endgroup$ – Jeff Y Dec 20 '15 at 17:36
  • $\begingroup$ Take a laser, put a slotted disk in front of it, and point the thing at a planet of alpha centauri, where the beam will have spread out to say 100,000km. Aim a telescope at your laser from that distant planet, and measure how long the light flashes and dark periods last. You'll get some astoundingly rapid numbers for the rate of shadow propagation. However, nothing is actually traveling faster than light, you've just enlarged a small thing to a huge degree. $\endgroup$ – Wayfaring Stranger Jan 13 '17 at 14:37
7
$\begingroup$

The darkness does not have a speed, as it's just the space the light travels through. It's always there until the brief instant a photon whizzes through.

It would be analogous to asking what speed the road is travelling at, rather than the car.

$\endgroup$
  • $\begingroup$ But the speed at which darkness fills that space back up, that's something to take in to factor- right? $\endgroup$ – Charles Truluck Dec 20 '15 at 5:14
  • 2
    $\begingroup$ The space is not being "filled" by darkness, but emptied of light. So the darkness, again, does not move. And the space is not empty anyway. The darkness is a myth. The photon is, in a sense, always passing through and always leaving and always elsewhere - it's spread out, a wave. $\endgroup$ – StephenG Dec 20 '15 at 5:39
5
$\begingroup$

Darkness is not a thing. It is just the absence of light. It doesn't have speed. Try observe the image: enter image description here

In this image this is shown that suppose there is darkness on any many light year far object if someone switch the torch in the direction of object and after some instant raise his hand and cover the light then before the light the darkness will reach on object which is completely wrong. Since the darkness which is assumed to be reach before light is the darkness there before the light reach on the object.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.