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

Michael S. Lorrey (
Wed, 17 Feb 1999 09:01:58 -0500

Jonathan Reeves wrote:

> 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.

no, each additional mph requires greater and greater amounts of energy to acheive.

> 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.

Yes it will because as any object approaches c, the object begins to increase in mass, thus posessing greater inertia. This is an electromagnetic based intertial resistance. It will require greater thrust to accelerate the same amount, and depending on the type of propulsion you use, the performance of the drive may be decreased as it approaches c as well. This is not unique. We have the same problem with jets approaching the sound barrier. Jets can pass the sound barrier because they are not made of air. Matter cannot pass the light barrier because all matter is, well, matter.

> Jon Reeves