# How To Travel at The Speed of Light

1. Jan 17, 2012

### JtValentine

Okay, so I'm no physicist, but I just had a random thought. So they say that traveling at the speed of light is impossible because the mass of the engine would have to be constructed infinitely big. But what if the propulsion didn't come from the spacecraft?

I was wondering what you guys and gals thought about a device that would pull the spacecraft to the speed of light, instead of push. Think of a slingshot.

It was just a random thought. It may be totally idiotic. I don't know, I just love physics. :)

What do yall think?

2. Jan 17, 2012

### D H

Staff Emeritus
The impossibility of traveling at the speed of light results from you having mass. Only massless particles can travel at the speed of light, and they must do so.

3. Jan 17, 2012

### Staff: Mentor

You'd still need 'infinite' energy, so a slingshot won't help.

4. Jan 17, 2012

### JtValentine

Ah. I'm dumb. Thanks!

5. Jan 17, 2012

### BF004

No matter how fast you are travelling, relative to how you started, you will still measure the speed of light travelling away from you at c. So basically, no matter how fast you get going, you are essentially never any closer to getting to close to the speed of light, since you will always measure the speed of light the same from every frame of reference.

Unless you are a nuetrino of course.

6. Jan 20, 2012

### Tracer

If you have the time to wait, you could let yourself free fall from infinity into a black hole. When you reach the event horizon you should have a relative velocity of c with the black hole in accordance with classical physics. However, GR might determine the relative velocity to be other than exactly c.

If you are in a hurry you could start from a shorter distance from the black hole and accelerate toward it such that upon free falling the rest of the distance to the black hole your relative velocity with the black hole is c when you reach the event horizon. Again, this is according to classical physics.

So in essence a black hole would be pulling rather than pushing you.

Last edited: Jan 20, 2012