why is faster than light travel impossible?

Question

I’m wondering if interstellar travel is possible. So I guess the starting point is figuring out FTL travel.

In: 1302

Answer 1

There’s lots of fun explanations here that are consistent with the math (the core rule of relativity is that the math is straightforward but the physical intuition is anything but), but my favorite one is this –

You can go as fast as you want; there is no limit. The problem is that, the more you accelerate, you also accelerate *through time*. You could get on a hypothetical spaceship and keep accelerating until you reach the other side of the galaxy in a couple of hours. The problem is that, once you arrived there, you would find yourself about 100,000 years in the future. In its own reference frame, light travels **infinitely fast** – that is, no time elapses when you are “moving at the speed of light”. To the stationary observer, this looks like there is a “speed limit” since more and more of your speed is actually into the future rather than through space.