Is Darkness Faster Than Light?

Written by OC Wanderer, author of Destiny Among the Stars, a LitRPG sci-fi series set in the real stellar neighborhood. Published August 28, 2026.

The world's biggest physics lab has found no way around the light-speed limit. A shadow offers a wonderfully strange next question: how can something so ordinary race across a surface faster than light without breaking relativity?

I wonder what it would take for a crew to ride that moving darkness. Picture its edge sweeping over lunar craters quicker than a beam could travel between them. Could a ship, or even a fresh message, hitch a ride? In Destiny Among the Stars, Luca's log says the crew found an "honest-to-god warp-speed engine" in a portal on Venus, and the Triumph flies on that. Real physics gives us a speed above c to investigate, but we need to look closely at what is doing the moving.

A flick of the wrist across the Moon

Imagine a laser powerful enough for this thought experiment, aimed at the Moon. A bright dot and a shadow's edge both depend on where light lands, so the dot lets us see the geometry. Turn the beam about 57 degrees in a second, or one radian. At the Moon's distance of 384,400 kilometers, the dot near the point facing us sweeps at about 384,400 kilometers per second, roughly 1.3 times the speed of light.¹ That is an extraordinary amount of apparent motion to get out of a turn of your wrist.

Every photon still travels from the pointer to the Moon at c. The light illuminating the next crater left the pointer a little later, aimed in a slightly different direction. The racing dot is a sequence of separate arrivals, so there is no photon sprinting sideways over the lunar dust. Physicist Robert Nemiroff, who studied beams sweeping across astronomical surfaces, writes that these speeds "cannot be used as a means of local communication."² Move a surface twice as far away and the same turn sweeps the dot twice as fast. I love how much speed the geometry gives us before we have accelerated anything along that track.

In Book 1, Chapter 26, Zoe traces a 2.3-second pulse near Proxima Centauri back to its origin using the transmission delay and Doppler shift. The lunar dot invites the same question: where did each arrival come from? Follow each ray backward and you return to the pointer, rather than the neighboring crater.

Can an astronaut send a message along it?

Suppose an astronaut at the first spot needs to warn an outpost 1,000 kilometers away the moment the dot passes. Could she put her warning onto that moving light? The photons heading for the second spot have already left the pointer before she can react. She can send her own radio or light signal, but it needs about 3.3 milliseconds to cross that distance; the swept dot takes about 2.6 milliseconds, carrying only what the pointer sent. I would love that shorter wait in an emergency, but the warning has to travel from the astronaut who just chose it. This is the rule from my post on why light is the speed limit: events too far apart for a signal at c to join them cannot send fresh information to each other.³

Back at the pointer, you can give the Moon a message. Open and close a shutter in a pattern and the lunar surface shows that pattern of light and dark. Every pulse takes about 1.28 seconds to arrive, just as a radio message would. It is tempting to watch the spot race over the craters and think the news must be racing with it, until you remember the journey each pulse made from Earth.

In Book 1, Chapter 26, Danny sees coherent structure in the Proxima pulse and takes it as evidence of something actively probing the ship, rather than natural interference. That is the sort of clue I would want a crew to notice: the pattern in the signal can tell them something about whoever sent it.

Darkness racing inside a crystal

The lunar dot is a thought experiment, but a research team measured fast-moving darkness on a microscopic scale in a study published in 2026. Inside a light wave, surrounding waves can cancel to leave a point of zero intensity, called a phase singularity.⁴ In a thin crystal where light travels as slow coupled waves, the team used an ultrafast electron microscope to track these points. Just before annihilation, their measured speeds exceeded c. The slow waves actually amplified the effect.⁵ That is a lovely puzzle: slowing the waves makes their dark patterns more likely to outrun light.

The paper itself distinguishes this motion from energy or information transmission. A dark point marks where the surrounding waves cancel; it is not a particle carrying something along its path. The authors also suggest ultrafast information flow in these media as a direction to explore. That possibility leaves me curious about what future experiments might achieve, but it is different from demonstrating a fresh message sent faster than light. The fast-moving darkness is fascinating enough without making it a working transmitter.

So is darkness faster than light?

Yes, a shadow can sweep across a surface faster than light, and microscopic dark points have been measured doing it too. The speed belongs to a pattern, which makes the prospect of riding it wonderfully slippery. I can imagine my crew spotting the racing edge and asking whether they have found a shortcut, then following the light paths until they see why it cannot carry them. The real payoff is discovering how much stranger motion can be than the movement of an object from one place to another.

A wave has crests and pulses moving through a real medium, and I wonder whether one of those could carry a message: what is phase velocity, and why can it exceed the speed of light without violating relativity?

Endnotes

1. NASA Goddard, “Moon Fact Sheet” (mean distance 384,400 km). Author calculation: 1 rad/s × 384,400 km = 384,400 km/s, which is 1.28 times c = 299,792.458 km/s, for the point straight ahead of the pointer on a surface facing it; 1,000 km ÷ 384,400 km/s = 2.60 ms; 1,000 km ÷ 299,792 km/s = 3.34 ms; 384,400 km ÷ c = 1.28 s. ↩
2. Robert J. Nemiroff, “Superluminal Spot Pair Events in Astronomical Settings: Sweeping Beams,” Publications of the Astronomical Society of Australia 32 (2015): e001. Primary research. The abstract states that superluminal spots on scattering surfaces do not violate special relativity and cannot be used as a means of local communication, and proposes a three-dimensional map of a target from controlled, repeated sweeps, since the timing of the spots depends on a surface's distance and tilt. ↩
3. Michael D. Stenner, Daniel J. Gauthier, and Mark A. Neifeld, “The Speed of Information in a ‘Fast-Light’ Optical Medium,” Nature 425 (2003): 695–698. Primary research. The abstract opens with the principle that no signal can cause an effect outside the source light cone. ↩
4. Wikipedia, “Optical vortex”. Context/definition. The dark point is the center of what optics texts call an optical vortex. An optical vortex is a zero of an optical field, a point of zero intensity, around which the phase circulates. ↩
5. T. Bucher et al., “Superluminal Correlations in Ensembles of Optical Phase Singularities,” Nature 651 (2026): 920–926; abstract and full preprint. Primary research. The abstract reports singularities accelerating to unbounded velocities before annihilation, with measured velocities exceeding the speed of light, amplified by the slow group velocity of hyperbolic phonon polaritons in hexagonal boron nitride membranes. The team includes Ido Kaminer. The full preprint (p. 4) distinguishes superluminal singularity motion from energy or information transmission; its abstract suggests ultrafast information flow in polaritonic media as a direction to explore. This does not establish a faster-than-light message. ↩