In school, you may have learned that nothing can travel faster than light. This principle, rooted in Einstein’s theory of relativity, holds true for objects moving through space. But there’s an important nuance that we didn’t dive into during those lessons: while nothing can travel through space faster than light, space itself is not bound by this rule. Space can expand at any speed it wants — and that’s where things get interesting.

How does space expand faster than light?

Imagine you’re listening to a radio host who is sitting at rest. From your perspective, they aren’t moving. Now, picture a galaxy at the far edge of the universe. Just like the radio host, the galaxy is also at rest from its own perspective. However, the space between you and that distant galaxy is expanding.

The light from that galaxy may be traveling toward you at the speed of light, but the space between you and the galaxy is stretching faster than the light can cover it. As a result, the light never quite reaches you — it’s as if the ground is constantly being pulled out from under the poor beam of light, no matter how fast it tries to get across.

Why is this happening?

This phenomenon is driven by the expansion of the universe, which has been ongoing since the Big Bang. The further away a galaxy is, the faster the space between you and that galaxy expands. Eventually, at extreme distances, the space is expanding faster than light can travel.

This is why some galaxies are receding from us faster than the speed of light, even though they aren’t breaking any physical laws — it’s the space between us that’s doing all the work.

What does this mean for the universe?

This faster-than-light expansion of space means that there are parts of the universe we will never be able to observe. As space stretches between us and distant galaxies, their light will never reach us, leaving those regions forever outside our view. In essence, the universe is continually creating “new” space, pushing some areas beyond our observational horizon.

So, while nothing can travel through space faster than light, space itself can and does expand faster than light. And that’s one of the great mysteries of our expanding universe.