Why can't we go faster than the speed of light?

[Selkie]

I demand a valid reason.

nao.

[Houdini]

Because we have mass, whereas light has none.

[Selkie]

Because we have mass, whereas light has none.

no I mean what would happen if we went faster than the speed of light?

[Samus Aran]

There is no absolute proof or anything that we can't. Only theories based on the theory of relativity.

Here's an interesting explanation that's not purely equation-based, though.

Now, let's go back to your starship. Let's assume that your engines are powered by tapping into some external energy source, so you don't have to worry about carrying fuel. As you get going faster and faster in your starship, you are putting more and more energy into the ship by speeding it up, so the ship keeps getting heavier. (Again, I should really be saying "massier" not "heavier" since there is no gravity in space.) By the time you reach 90 percent of the speed of light, the ship has so much energy in it that it actually has about twice the mass as the ship has at rest. It gets harder and harder to propel with the engines, because it's so heavy. As you get closer to the speed of light, you begin to get diminishing returns — the more energy the ship has, the heavier it gets, so the more energy that must be put into it to speed it up just a little bit, the heavier it gets, and so on.

The effect is even worse than you might think because of what is going on inside the ship. After all, everything inside the ship, including you, is speeding up, getting more and more energy, and getting heavier and heavier. In fact, you and all the machines on the ship are getting pretty sluggish. Your watch, for instance, which used to weigh about half an ounce, now weighs about forty tons. And the spring inside your watch really hasn't gotten any stronger, so the watch has slowed way down so that it only ticks once an hour. Not only has your watch slowed down, but the biological clock inside your head has also slowed down. You don't notice this because your neurons are getting heavier, and your thoughts are slowed down by exactly the same amount as the watch. As far as you are concerned, your watch is just ticking along at the same rate as before. (Physicists call this "relativistic time contraction.") The other thing that is slowed down is all of the machinery that is powering your engines (the dilithium crystals are getting heavier and slower, too). So your ship is getting heavier, your engines are getting sluggish, and the closer you get to the speed of light, the worse it gets. It just gets harder and harder and harder, and no matter how hard you try, you just can't quite get over the light barrier. And that's why you can't go faster than the speed of light.

[Himu]

Because light is faster than the time it takes for the earth to revolve/

[Blaze-Senpai]

There is no absolute proof or anything that we can't. Only theories based on the theory of relativity.

Here's an interesting explanation that's not purely equation-based, though.

That actually made some sense.. I think

[The artist formally known]

If we went faster then the speed of light we'd be literary going back in time.  caterpie;

[spoiler]Well, we're really just going so fast that time is going slower then us so it's not going back in time, it's just that time slows down sorta.[/spoiler]

[Samus Aran]

Well, we're really just going so fast that time is going slower then us so it's not going back in time, it's just that time slows down sorta.

It only "slows down" because our perception slows down.

[The artist formally known]

It only "slows down" because our perception slows down.

So what? Still awesome  caterpie;

[Selkie]

so basically, light is faster than time?

[The artist formally known]

so basically, light is faster than time?

Light speed is time. I forgot how they explained it. Also time isn't real, it's just a measurement made by humans so what I said about going back in time really isn't impossible as it seems (though I doubt humans will ever be able to travel back in time.)

Yeah it's still pretty impossible though.