Q: Is darkness a wave the way light is a wave? What is the speed of dark?

Physicist: The very short answer is no: darkness is not a wave.  There are no waves in the dark for very much the same reason that there’s no surfing (or ocean waves) in Death Valley.  Darkness, being an absence of electromagnetic waves (light) has nothing to do any waving.

There are waves in the ocean, because in the ocean there’s stuff to do the waving.  Having nothing to wave, deserts are waveless.  Darkness doesn’t involve waves because it’s a lack of electromagnetic waves.

If you define the speed of dark to be the speed at which you could find out about someone turning out the lights, it’s exactly the same as the speed of light: 671 million mph, or 2.99 x 108 m/s, or about 1 foot per nanosecond.  For example, if the Sun were to suddenly go out (unlikely), then the darkness wouldn’t get to the Earth for a solid 8 minutes.

The somewhat longer answer (that sound like it undermines the short answer, but totally doesn’t) is that “darkness”, while not a wave itself, can be produced by light waves.  Light waves, rather than merely being there or not can add and subtract from each other (at each tiny point in space).

You’d think something like light and dark would be an either/or sort of thing, like eggs (for example).  But while eggs always add, light (and any other kind of wave) can add or subtract.

So if you’re looking at a particular point in space there can be light waves present, but they may cancel each other out, creating a little dark patch.  In this sense light has more in common with money than most “actual” things.  You can have positive money (colloquially; “bones”) or you can have negative money or debt (vernacularly; “boned”), and it’s not unless you have neither, or equal amounts of both, that you’re exactly broke.

White=1, Black=-1, Grey=0. Notice that the patches are moving faster in-between the sources.

Light is similar.  Correctly prepared light can produce doubly bright or completely dark regions.  What’s really slick, is that these regions can move faster than light!  There are a lot of effects like this that get a lot of people excited, but before you get too excited; don’t.  It has to do with the difference between “phase velocity” and “group velocity”, but the basic idea is that these dark and light patches move faster than light in exactly the same way that the intersection of the blades of a pair of scissors move faster than either blade.  There’s an old post that talks about one of the more exceptional examples of this.

Long story short: darkness isn’t a wave itself because it isn’t anything, if it has a speed it’s the same as light speed, and also light is profoundly weird stuff (and not to be taken lightly).

The ocean, desert, basket, and hypnotic pictures are from here, here, here, and here.

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37 Responses to Q: Is darkness a wave the way light is a wave? What is the speed of dark?

1. Darkness is a wave or not I don’t know about that. But if darkness is not a wave then whats about “Dark Energy”???

2. Someone says:

3. larry walden says:

You have got to be kidding. Anyone with common sense knows that darkness is the absence of light, like in a moral sense evil is the absence of goodness. I define “absence” in the dictionary meaning of nonexistence….ka put….nothing or nothingess.

4. Quantum vacuum fluctuation have broken the symmetry of nature due to which our universe is existing with four fundamental forces of nature…

5. Quantum Vacuum fluctuation have created the Space-time of our Universe to inflation..!

6. larry walden says:

This is one of the most nebulous and confusing science articles i have read in a long time. It also sounds contradictory in part. I have read this article more than once and am still scratching my head.

Come on professor. You say there it is (light) and there it “ain’t”. You still can not get around the fact that darkness is the ABSENCE of light……….nothing unless you want to include that dark matter stuff that physicists/astronomers are struggling with.

7. JonL says:

I’ve actually though about this. Everyone thinks we need to be a ble to travel faster than the speed of light to go through space. In actuallity, we need to be able to surpass the speed of dark. Darkness is constant. Always there. Light is fleeting. Turn off the stars and darkness prevails. Darkness is not the absence of light, because darkness exists even in when there is light. Give it enough thought. You’ll see it too.

8. Jack Dooney says:

My guess is that this is a question from a fan of Terry Pratchett. In his satirical Discworld series nothing is faster than dark because no matter how fast light is dark has to be faster to get out of its way. And due to the heavy magical field, light isn’t all that fast, just slightly faster than sound.

So, shadows and light spots could move faster than the speed of the light?

10. Larry Dale says:

None of the analogies really fit because it all depends on definition. If one defines light as that which we humans can see then ligh and dark exist together. But if the definition is EM then most of our known universe is filled with EM in one form or another so in that sense there is no ‘dark’ place. DM and DE really don’t alter this because whatever they turn out to be in the end will either modify the SM or be contained within it thus consist of some particle/wave (Baryonic or otherwise). Maybe will have something worry about if DM an DE violate (ultimately) E=Mc^2.

11. Stuart Scott says:

I came here to try to understand a passage of Scripture that says the God created “darkness”, and was there a physical way to understand that passage?

12. Philip says:

Well, darkness and outer-space both are not nothing because nothing doesnt exist (if it didnt exist then we could not think of it, could you say that you can think of nothing if you can call it something?) in complete darkness we can still feel and hear things and we are not surrounded by nothing at that moment, we are just incased in a total eye-sight of black. it may be true that we would die in outer-space without imitating our earth environment but that does not mean outer-space is nothingness because if outer-space was nothing then we wouldn’t be traveling through it and there would be no distance. if there is distance there is something… for example could you travel from point 1 to point 2 through 0? answer: no, because 0 doesn’t exist and cannot be a passage. 0 only exists as a measurement because it is used to see a lack of one kind of thing or a set of things. there can be no absolute 0 of all things at once, why? because something exists, and there is evidence all around you. it may be that space is infinite but it is not nothing, because it is “space.” we may be unable to sense/know what’s in outer-space because it is not possible with our current senses or technology, but because we can’t sense or understand it does not mean it is nothingness. are our senses perfect, and we can sense all things? no.

13. Steve says:

Wait what? Doesn’t light bounce in every direction? Isn’t the existence of light purely relative? Where we see black other animals see everything, Wth are you saying? Smh I’m no physicist but if animals can see where we can’t while using eyeballs, that would mean the existence of light is relative, a worm has no eyes and see’s no light, so therefore it doesn’t exist for the worm. Again if light radiates in every direction and bounces off of surfaces it is safe to say the whole damn universe is lit up, yet darkness wins.

14. Steve says:

Darkness doesn’t need light, light needs darkness. Therefore darkness is the presence of darkness and light is the absence of darkness

15. Teal says:

darkness is just shade. the light is still there you just dont see it with your eyes. the vibrations and waves are still there. even if the ocean has no wave that you see it still is a wave because it still keeps moving. darkness moves at the speed of light because they work interchangeably.

16. Xerenarcy says:

(for simplicity brightness = luminous flux)
dark is the absence of light, ergo dark = 0 brightness.

you can make some interesting abstract ideas out of this, such as “darkness is the property at a point that contains equilibrium of the quantity of photons in all directions”.

17. Scott says:

If you were to instantaneously pop a planet into existence close to the earth would we detect its gravity at the same time we would detect light shining from that planet? If so, and gravity is not really a part of the electromagnetic spectrum (maybe it is?) then it seems that the speed of light is more like a speed of reality threshold.

18. Bill says:

Darkness at the most can contain the echoing of sound waves,,but in itself darkness is incapable of creating light..so can someone tell me how light came into exsistence.

19. ash says:

To steve.regards light not existing for a worm because it has no eyes is wrong it exists in another sense to a worm as heat.As it would do for a blind human.Light still exists for them but as a thermal effect.

20. deepak desai says:

Hello there
Frankly speaking, the darkness is greatly neglected part from studies.
We all , all of us little or more forgotten that many things took birth in the darkness.

21. Pingback: What Is The Speed of Dark? | Help

22. Pingback: What Is The Speed of Dark? | Woowix

23. David T says:

As Leonard Susskind says, ” we’re prisoners
of our neural architecture, some things we can
visualize, other things we cannot”.
The darkness always holds some form of
Electromagnetic wave, we are just not always
equipped to see it. There is always vibration,
no part of the universe is totally frozen.
Therefore light is always present, even if we
can’t see it, and darkness doesn’t exist at all.

24. Alan Christ says:

The fastest object that moves within that darkness

25. Bryan says:

Maybe we should think of darkness as an energy that simply filled all the light in the universe rather than light being created from darkness (everything beginning with light). You need the darkness to distribute the light in order to see in the world just as you need light to fill the void of darkness. One can over come the other, therefore they coexist. Darkness is an invisible energy that we can’t measure because we can’t see or feel it. Darkness may not be fast, it may be extremely slow and light weight;just like bacteria. We can’t see light because it’s too fast, darkness seems to be constant in our universe maybe because there are more dark particles than that of light. We exist in the dark and in the light.

26. Angel says:

@Bryan:

No. Light is an energy of its own. What we call darkness is a lack or scarcity of that energy. Light is just the processing of electromagnetic waves that contain frequencies within the detectable, visible range, for humans and other eyed organisms. The concentration of electromagnetic waves in a given space determines how much light there is, because the brain processes it as more packed and dense. Darkness is when there are few or no waves. The blackness we see results from lack of waves.

27. Angel says:

@juges debneth:

Dark matter is non-baryonic matter that makes up the universe. We call it “dark” because it is invisible to the current technology (and potentially to all technology possible). If it is invisible, it means it emits no detectable light, which is why it represents darkness. It has nothing to do with waves.

28. ben says:

if darkness is a lack of waves, darkness must be a perfect representation of total nothingness as perfect symmetry

29. Nkosinathi Zamisa says:

Then if darkness is not a wave, what does the light do to make darkness disappear?

30. Chris Santiago says:

Light exists as both a particle and a wave. Darkness does not. My thinking about the nature of darkness itself, is not just that it travels at the same speed that light does, but that darkness will always be there waiting, no matter how fast light/energy travels. Which deals with a more philosophical conceptualization between the two.

31. Nkosinathi M Zamisa says:

No darkness is simple the absence of light so there is no way that darkness could be a wave therefore it it isn’t wave it doesn’t have speed because it is not in motion.

32. TheEndlessCycle says:

Everything is something you cant have nothing or it would not be

‘why you see dark?’
It means that there are somethings.
So dark is………..

34. Angel says:

@Nkosinathi Zamisa,

Darkness is an absence of light waves, it is like an empty bowl. Light waves fill that emptiness so that it no longer exists.