# why does light go so fast?

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why does light go so fast?

In: Physics

It has no mass. Things without mass always go the maximum speed possible and nothing slower.

The speed of light is a bit of a misnomer, as it implies that only light travels at that speed. It is much closer to a “speed of causality”, the maximum speed at which anything can occur. It is the upper speed limit that binds all forces. Any particle that has no mass, such as the photon and the gluon, will necessarily travel at the speed of light of its medium. Additionally gravitational wave, radio waves, x-rays, and other waves of the electromagnetic spectra travel at this speed.

Anything that has mass can not travel at or faster than the speed of light as doing so would require infinite energy. /

It’s like the render speed of the universe. Nothing can go faster. Everything with no mass goes at that speed, not just light. And everything with any mass *must* go slower because it would take literal infinite energy for mass to go that fast. Not just a huge amount but *infinite*, so it’s impossible.

It would be better to call it the Universal Speed Limit rather than the Speed of Light, because lots of other stuff goes that speed. Even gravity. If the Sun instantly stopped existing, Earth would orbit the place where it was for about 8 minutes. Then its light and its gravity would both stop affecting us at the same instant and we’d fly straight off in the dark.

ELI5 answer?: Because nothing is stopping it. Light travels at the speed of causality through a vacuum because there’s no interaction happening to drag on it.

It kinda depends on what you mean by “why”. One reason is because it’s massless. Any and all massless particles will travel at the speed of light. Now if your question is why that speed and not something else, well that doesn’t have an answer (yet). We could pretend to live in a different universe where the laws of physics are different. Maybe in this one, the speed of light is slower. Well that would mean we would experience Einstein’s theory of relativity at everyday speeds which would not be good. It would also mean that atoms fly apart so also not good! But again, we don’t know *why* our universe chose the value it did.