Why Can't Anything Go Faster Than Light?
It's not an engineering limit. The speed of light is built into the structure of cause and effect itself.
By Cosmic Discovery Hub Editorial · Published 2026-09-24 · Updated 2026-09-24
A speed limit written into reality
299,792,458 metres per second. Light in a vacuum always travels at this speed — and, according to Einstein's special relativity, nothing with mass can reach it, let alone pass it.
The real reason: energy diverges
As an object accelerates, its relativistic energy grows by the Lorentz factor γ = 1/√(1 − v²/c²). As v approaches c, γ approaches infinity. Reaching light speed would require infinite energy.
See how γ explodes near light speed in the Time Dilation Calculator.
Causality is at stake
If signals could travel faster than light, some observers would see effects happen before their causes. The light-speed limit is ultimately what keeps cause before effect for everyone.
What about the expanding universe?
Distant galaxies can recede faster than light — but that is space itself expanding, not anything moving through space. No information outruns light locally, so relativity survives.