Re: Best choice of FTL fuel?

On Jul 24, 12:24 pm, Peter Knutsen <pe...@xxxxxxxxxxxxxxxx> wrote:
Nevermind *how* FTL works.

Nevermind *how* your car works, just think up an interesting fuel
for it.

The point is, it needs some fuel, because fuel-using
FTL makes for *better* worldbuilding than non-fuel-using FTL. It works, and
that's it, we don't discuss how or why, but we do know that you have to feed the
hungry engine with some regularity.

For values of "better" ~= "makes material resource allocation/
conflict themes available to storyline" maybe.

The question then becomes, what substance should be chosen by the world builder
as the required fuel?

Horse, then cart. Your thinking is why we don't dare look too
closely at the details of things that sound cool on the surface like
certain sub-genres of steampunk, Baxter's _Anti-Ice_ notwithstanding.

The fuel should be one that stores enough energy to make the FTL
drive work*, be cheap enough to be commercially viable, be safe enough
to store on ships with humans aboard, and so on. BTW, why should there
be only _one_ fuel? Space piracy would be a lot riskier (i.e. more
interesting story-wise) proposition if the next ship you boarded
carried Diesel but you burned gasoline (so to analogize).

The famous Traveller RPG setting uses ordinary hydrogen,

If that's your preference then use it; don't waste everyone's time
justifying it.

Low-brow sci-fi television shows often use fictional materials, but we'll ignore
those

Let's don't. Star Trek in particular used matter/antimatter, which
the public was already familiar with as a high-density energy storage
medium, and that's exactly what you need for any "fuel-using" drive
(never mind it can't provide enough energy). It used fictional
materials to convert the stored energy to a form that could move the
ship FTL because somebody involved decided that warp drive was a field
effect roughly analogous to magnetism but iron warp coils weren't
going to do the job.

and confine ourselves to known substances, as well as materials that
scientists assume to exist somewhere out there.

You mean as an energy-storage medium? You _are_ aware that empty
vacuum theoretically holds more energy per volume than any possible
form of matter? Yes, the trick is getting it out, but still.

(snip H/He dither)

What other FTL fuel choices are there, if one recognizes the fact that
compications and logistical problems make for better worldbuilding than
"push-the-button-and-it-goes" problem-free wonder technology (much as I like
Iain M. Banks' stuff)?

That's not only not SF, it's not any kind of fiction; just fantasy!

Even an FTL drive that used vacuum energy would need maintenance.

Apart from abundance, ease of transport may also be important. How difficult is
it to move helium? Liquid hydrogen isn't too easy, as far as I know, but we have
some idea of how to do it, and we're gonna become much better at it in the next
couple of centuries.

Well, vacuum is available literally everywhere free of cost, takes
up no storage space, and carries no inertial mass penalty.

Ideally, starships should spend quite an amount of their capacity (mass) on FTL
fuel storage, if they want much range (or speed); not entirely unlike the
Traveller RPG setting.

Look, if you like the Traveller universe _that_ much, just write in
it. Apparently they do the shared-universe license thing, or at least
have according to Wikipedia:

http://en.wikipedia.org/wiki/Traveller_(role-playing_game)

see "Traveller in other media".

As for how much of a ship should be tankage, a vacuum-fueled ship
wouldn't need any but the size of the engine that extracted energy and
applied it would be proportional to the size and desired speed of the
ship, I'm thinking.

*Considering that just to get to c (much less past it) you need
_infinite_ energy, what possible fuel will do?


Mark L. Fergerson
.

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