Photo by: Getty Images

Getty Images

Darkness Is Faster Than the Speed of Light

By: Reuben Westmaas

Does darkness really have a speed?

August 01, 2019

Nothing's faster than the speed of light. Except the speed of dark. That might sound like the tagline of a grim and gritty movie that's trying way too hard, but it also happens to be true.

Photo by: Shutterstock

Shutterstock

Shadow Racing

This is a little hard to wrap your head around, but shadows can move faster than the speed of light, even though nothing can move faster than the speed of light. In a second, we'll explain how exactly that's possible without breaking the most fundamental law of physics. But first, this thought experiment might make things clearer.

Imagine you have a light that's powerful enough to reach the planet Jupiter. Imagine also that it casts that beam in a cone that's broad enough to cover the entire diameter of the planet. When you pass your finger over the lens, the shadow will cross the entire diameter of the planet — a distance of 86,881 miles (139,821 kilometers). The speed of light is 186,000 miles per second (299,338 kilometers per second). So if it takes you less than half a second to move your hand that distance, then that shadow will have "broken" the speed of light.

Shining a Light on the Subject

So, remember how we said that nothing can move faster than the speed of light? Well, that's the key. Shadows aren't anything. Shadows are the absence of something — specifically, photons, or particles of light. Since there's nothing that's actually traveling the distance, the only thing that's "moving" is an area where photons aren't. There's no information that's being transmitted faster than light, only a blockage of information. That means your interplanetary shadow-puppet show doesn't break any physical laws — only the hearts of your interplanetary audience.

This article first appeared on Curiosity.com.

Next Up

Mapping Dark Matter in Outer Space

Scientists in Zurich are using facial recognition-style algorithms to map what we cannot see in space.

What If Dark Matter Doesn't Exist and the Law of Gravity Is Wrong?

Dark matter and gravity have scientists at odds.

Why Does Pluto Have Such a Weird Orbit?

Pluto is the black sheep of the planets in our solar system and it looks like astronomers aren’t sure how long Pluto will remain in its present orbit.

Last Call for the King of Planets

This month Jupiter is entering conjunction which means it's the last chance this year to catch a glimpse of the largest planet in our solar system.

Celebrating Hubble's 30 Year Legacy

Three cheers for the Hubble! First launched in 1990 aboard the Space Shuttle Discovery, the storied space telescope is celebrating is thirtieth year in lonely orbit around the Earth.

May Sky Watch: What to Look Out For This Month

Whether you can see it from home or stream it online, here are some of May's wonderous celestial events.

When Was There Life on Venus?

What we have is a cosmic whodunit. Venus, the second planet from the sun and considered by the more romantic types as "Earth's twin" and the avatar of love, is dead.

Check out the Earth’s 800,000 Year Old Battle Wound

Scientists may have discovered the location of an ancient buried crater, a result of a meteorite that barreled into the Earth some 800,000 years ago.

The Coronavirus: What You Need to Know About the Virus

As the death tolls rise, Coronavirus is on the minds of people all over the world. Learn about this new virus and how we got here. Originally published: 2/20/2020 Updated: 3/9/2020

July in the Sky: Celestial Events Happening This Month

With eclipses, meteor showers, and more, it's a busy month in the night sky this July. Take some time this summer to look up and enjoy these cosmic wonders.