Why can’t anything travel faster than light and what would happen if it did?

– Sai Karthikeya Duggirala

Albert Einstein’s equation E = mc² says energy and mass are linked. If you push an object to go faster, you add energy to it. At everyday speeds, this just increases the object’s velocity. But as you approach the speed of light, the extra energy starts adding up to the object’s effective mass instead.

As the object becomes heavier, it also becomes harder to accelerate. To reach the actual speed of light, an object with mass would become infinitely heavy and require an infinite amount of energy to move. Since the universe contains a finite amount of energy, reaching light speed is impossible for anything made of matter.

Because space and time are woven together, travelling faster than light in vacuum would likely mean travelling backwards in time. You might see a glass shatter before it hits the floor or receive an answer to a question you haven’t asked yet. Physically, the laws of nature would break, creating paradoxes the universe currently prevents.

It’s possible to travel faster than light in a particular medium, e.g. electrons can outpace light in water. The limit is light’s speed in vacuum.