# Re: starship-design: Genuine STR question

```Johnny Thunderbird wrote:

> These particles approach the asymptotic limit C;
> as they do, the energy increment you must supply
> to produce further acceleration grows exponentially.

Correct.

> Your labor is not unrewarded, for the "extra" energy
> ( departure from linear Newtonian term ) you have
> placed into accelerating these stubborn particles,
> shows up as an increase of their mass.

Not in _your_ reference frame. In the reference frame of an observer
moving WRT you, or vice versa. In your reference frame, all of your
particles are exactly the same. Note: 'mass' doesn't increase per se
when you approach C...rather it is your kinetic energy that goes to
infinity. Think of it as a resistance to further acceleration.

> transfer is a function of their new equivalent mass,
> not of their rest mass. In short, your overall reaction
> engine is boosted by the multiplier amounting to the
> relativistic increase in mass you impart to your ejecta.

It doesn't work that way. I won't get into the mathematical proofs, but
it is shown in several books that you simply cannot get either: 1.
enough mass, or 2. the mass to 'increase' enough, to accelerate you to C
and beyond. It can't be done with a normal engine. If you have a
different type of engine, say, one that zeroes your inertia or mass,
then maybe. But not like this.

Relativity, despite what some say, is not easy to understand or learn.
You will do what I did at first: look at it and say: huh? You'll also
have a tendancy to say that the observers on earth are somehow more
privileged than those on the ship, but it is not so. It doesn't really
make sense at first. To me, it still seems inadequate, so I am waiting
for a theory of quantum gravity to be found. Or something like it. But
stick with it, ask people questions if you don't understand something.
No question, if honest, is ever stupid.

Kyle R. Mcallister
```