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Re: [GZG] Gzg-l Digest, Vol 37, Issue 14

From: Samuel Penn <sam@g...>
Date: Mon, 13 Sep 2010 08:50:42 +0100
Subject: Re: [GZG] Gzg-l Digest, Vol 37, Issue 14

On Sunday 12 September 2010 03:48:09 John Atkinson wrote:
> On Sat, Sep 11, 2010 at 11:30 PM,  <gzg-l-> wrote:
> > On Thursday 09 September 2010 04:26:43 John Atkinson wrote:
> >> I'm doodling here, so here goes nothing. . .
> >>
> >> Presumptions:  No nanotech "magic wands", technology levels
> >> roughly equivalent to Drake's Hammer's Slammers, Jerry Pournelle's
> >> CoDo series, and similiar novels.	Volume matters when shipping
> >> across space, mass relatively less so.
> >
> > Any particular reason? Mass is the most important factor in
> > reality.
> 1: Contra-grav.  The way it has always worked in my brain (mine, I
> decline to speak for anyone else--but I'm pretty sure this is how it
> works in Marc Miller and Frank Chadwick's brains too) is that within
> the 'envelope' of a CG suspension, the planet's gravitational pull is
> cancelled out, so the limiting factor is how much stuff you can stuff
> into that CG envelope.

Okay. Unless you're cancelling the entire vehicle's mass though
(Bergenholms?) to accelerate you still need to push your mass
around. Outside an atmosphere, that's entirely dependent on mass
and unaffected by volume.

At which point it comes down to which is cheaper - increasing the
CG field or increasing the thrust.

> 2: To be redundant, I got started playing Traveller a long time ago,
> and I think it damaged my brain.

When I ran Traveller, I made some changes to the tech to make it
a bit harder. Contra-grav is too much like magic for me, and gets
rid of lots of interesting difficulties, therefore making the
setting less fun (IMO).

CG can also give you perpetual motion machines, and hence limitless
free energy.

> 3: I'm presuming you want to ship stuff inside your starship, not
> strapped to the outside.

You still need to push it.

The way I see it though, is if you want a bigger cargo hold, you
need more hull, which adds a little bit to mass (volume increases
with the cube, hull mass only increases with the square).

If you want to carry more mass, you also need bigger drives,
which may require bigger power sources and more fuel/reaction mass.

> 4: I'm also presuming that FTL drives, when engaged, pull along
>  things within a certain volume, not up to a certain mass limit.

Would this lead to spherical ship design?

If you have a Traveller-like 100 diameter limit for FTL, then
mass will affect acceleration and how quickly you can get to
a safe jump point.

> John
> who is NOT a physicist, not even a little bit.

Neither am I, but I'm better at pretending physics than pretending

Be seeing you,
Sam.			    Mail/IM (Jabber): 
Gzg-l mailing list

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