[rhth54656]

But the more you accelerate the spaceship, the more energy you need, with the energy diverging to infinity as your speed approaches that of light. At some point, your spaceship will become so energetic that it, too, will collapse into to a black hole.

That is simply wrong. It is called relativity for a reason. An object might be traveling arbitrarily fast, but in its reference frame it is not moving.

That pretty much invalidates that part of the article.

For curious readers: http://physics.stackexchange.com/questions/3436/if-a-1kg-mas...

[KVFinn]

>Dear Readers: I apologize; there's one point in this article that's not quite right and ought to be clarified. Namely, when I said that a spaceship traveling exponentially close to the speed of light would collapse to a black hole: that's only true because, when the spaceship inevitably collided with some interstellar particle, the energy in the center-of-momentum rest frame would be exponential. A spaceship in a theoretical vacuum could get arbitrarily close to the speed of light without collapsing.

>However, it's important to understand that this doesn't change the computational situation in any important way. It's still true that, to accelerate exponentially close to the speed of light, you need an exponential amount of energy! And therefore, it will take you exponential time to accelerate to such a speed---unless your fuel tank (or whatever else is providing your energy) is exponentially concentrated, in which case it will exceed the Schwarzschild limit and indeed collapse to a black hole.

[rhth54656]

That is only true if assumed that the rocket will not gather additional energy on the trip.

Also the premise that the energy has to be concentrated to a certain are for the rocket to work is wrong. You can have as much energy on as large area as you want without reaching the critical mass and collapsing into a black hole. The rocket can be of any size to work.

Even so, a black hole is the perfect source of energy. Converting mass into energy without loss via hawking radiation. And the mass is collected when moving trough interstellar medium. Such micro black hole( it has to be small to radiate fast enough ) would still weight a lot and moving it would be difficult, but not impossible.

[noselasd]

Only the black hole part. As speed increases, mass increases too - and mass is energy. (Which is also why we can't have (anywhere) near speed light space travel, there's not enough energy anywhere to maintain accelerating the increasing mass)

[rohansingh]

An object can accelerate arbitrarily, but in any reference frame it will never be traveling faster than c.

Of course, it won't collapse into a black hole, but the amount of energy needed to accelerate further will increase asymptotically.

[rhth54656]

That is actually false from the frame of the traveler. Using constant acceleration, the traveler will observe constant energy usage. Then length contraction will guarantee that you can reach speeds arbitrarily close to speed of light( and also any location in the universe ) in about ~50 years with 1G acceleration.

http://en.wikipedia.org/wiki/Space_travel_using_constant_acc...

[AnimalMuppet]

Yes, but when do you get there? In 50 years in your time, but it may be a few billion years later in their time...

[rhth54656]

I believe that is the point. Even more time for the stationary computer to finish the calculation.

[abdullahkhalids]

Note the Scott has made a correction in the comments.

[andrewflnr]

Also, I can't see how, theoretically, your ship turning into a black hole would prevent the answer to your computation from being received.