What is special about the speed of light? Why isnt it faster or slower?

Question

I sort of get the idea of how nothing can go faster than the speed of light but it always bugged me in the back of my mind and seems like it shouldn’t be how the universe works

In: Physics

Answer 1

The super-simple, ELI3 answer I gave my son when he asked was: The speed of light is how fast you go when you weigh nothing. Asking why you can’t go faster is like asking why you can’t weigh less than nothing.

If there were no brakes, if there was no matter weighing stuff down, then everything would travel at that speed. But there is “stuff,” and stuff is heavy. So when you’re made of stuff, you get weighed down and can’t go as fast. We all grew up in a world made of stuff, so we made measurements of how fast stuff travels under certain conditions. We came up with measurements like miles-per-hour or whatever. We came up with ways to measure how much energy it takes to move stuff at a certain speed, and we discovered formulas and equations, like *F=ma,* and we attached numbers to those measurements.

And once you have equations, you can plug in different numbers and play with them, and it turns out that if you weigh zero, then you would move at about 300,000km/second^(1) according to the measuring system we use. There’s nothing magical about the number 300,000kn/sec, I’m sure some people on another planet somewhere call it something else, but it’s just how fast nothing goes.

The reason this all got so confusing is because of Einstein and his friends. People started noticing that you could set up an equation where light (or nothing) could be measured differently depending on where you were standing. The famous “Twins Paradox.” Einstein was the guy who finally realized–and proved–that time itself was malleable. If things reach the top limit speed-wise, then there’s no more room for movement, so something else must change. And this turns out to be a scientific fact. Time is different depending on your situation.

But the speed of light is just “speed.” It’s how fast everything wants to go, but it’s weighed down with all this stuff.

^(1. This is a huge oversimplification, but it’s an ELI5 question.)