RE: BOOKS: Pournelle's *A Step Farther Out*

Jonathan Reeves (JonathanR@mail.iclshelpdesks.com)
Wed, 17 Feb 1999 13:27:30 -0000

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Anders Sanberg writes:

> I think you misunderstood me. If your spaceship accelerates at 1 G, a
> classical calculation would say that after one year you would travel
> faster than c. However, in relativity (and as evidenced in particle
> accelerators) even a constant acceleration doesn't lead to a velocity
> greater than c. What happens is that the mass of the accelerated
> object increases as 1/sqrt(1-(v/c)^2) and the energy needed to
> accelerate it to a few percent higher velocity diverges.

The energy needed to accelerate it from it's _starting_ point increases, but not the energy it needs to accelerate itself. An object/vessel which is capable of generating it's own thrust will not need to output more power to maintain a constant acceleration the further it gets from it's origin.

Jon Reeves



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Anders Sanberg writes:
> I think you misunderstood me. If your spaceship = accelerates at 1 G, a
> classical calculation would say that after one = year you would travel
> faster than c. However, in relativity (and as = evidenced in particle
> accelerators) even a constant acceleration = doesn't lead to a velocity
> greater than c. What happens is that the mass = of the accelerated
> object increases as 1/sqrt(1-(v/c)^2) and the = energy needed to
> accelerate it to a few percent higher velocity = diverges.

The energy needed to accelerate it from it's = _starting_ point increases, but not the energy it needs to accelerate = itself.

An object/vessel which is capable of generating it's = own thrust will not need to output more power to maintain a constant = acceleration the further it gets from it's origin.


Jon Reeves