# Re: starship-design: Re: FTL travel

```STAR1SHIP@aol.com writes:
> >   > The increased relativistic 1/2 ton mass
> >   > approaches infinity as the velocity approaches light speed.
> >   > This real difference in the masses and resulting energy is the factor
> you
> >
> >   > underestimate the velocity obtainable by my machine.
> >
> >  But if the fuel gets heavier as the ship goes faster, so would the ship,
> >  and therefore that increasing amount of energy you think you'd get would
> >  have to be applied to an equally magnified payload mass.  The effects
> >  cancel out.
>
> You skipped a step the mass that needs to be converted to provide the
> relativistic energy you calculated was the relativistic mass. To get
> the mass wrt the ship you have to use the mass transform the other
> direction (that is why the are called transformations as they go both
> ways with equal validity) to arrive at the 1/2 ton mass I did unless
> you made some sort of math error I did not catch.

The ship carries the fuel.  Either both the ship and the fuel get more
massive with velocity or both the ship and the fuel stay the same mass.
Are you claiming that the fuel gets more massive but the ship that
carries it stays the same?  Either way the fuel can only provide so much
acceleration, and that little fission fuel can't propel a heavier