Re: [FT] The Sa'Vasku

On Sat, 5 Dec 1998, Thomas Barclay wrote:
> Brian spake thusly upon matters weighty: 
> Is this possible? I'm not sure it would work. I think that falls into 
> a popular fallacy about space: That space is cold (ducks and prepares 
> for salvo fire from the physics guys out there). 

space is cold, it is just also not very dense :-). however, you can
still
move heat about by radiation; as every schoolboy learns, heat can move
by
conduction, convection and radiation - in space the latter is the only
method. space is quite a good medium for infra-red radiation to cross,
as
it is largely empty.

> I was under the impression space was not cold, rather it had a lack 
> of temperature - because as I understood it temperature is a property 
> of matter relating to how excited or how expanded the particles were 
> and what phase they were in or some such. As a result, space being 
> largely empty, doesn't really have much of a temperature. 

you can also measure temperature by looking at radiated heat, and the
universe has a measurable temperature of 3 K, or about -270 celsius.
this
heat is what is left over from the big bang. the things in space - stars
and the like - are usually a lot hotter.

> And you can't effectively lose heat in space (by ejecting water) 
> because (I could be wrong) the water has no nearby particle which it 
> can transfer its energy (heat) to, therefore it is unlikely to 
> freeze. I believe you require a transfer of energy between molecules 
> or some such to change temperature. 

water in space can lose heat by radiation, and so can freeze, as someone
else has already calculated and posted. however, mercury would freeze
far
more slowly, as, being highly reflective, it cannot radiate heat as
well.
i tend to think that heat loss from vaporisation will be far greater
than
radiated heat loss, however.

> This is illustrated by one of the main space shuttle problems: 
> Overheating. The humans and equipment inside radiates heat. It 
> doesn't (because it can't) radiate into space. So things get warm. 

the shuttle, and other spacecraft, get hot mostly because of radiated
heat
from the sun. this can be dealt with by rolling the ship (i think this
is
called barbeque mode, or donner kebab mode to the brits) or having
circulating coolant.

> > How about "Mister" for your organic sandcaster? Instead of spraying
sand,
> > it sprays water/some other liquid - which in space instantly freezes
into
> > ice crystals anyway, giving roughly the same effect. fits the
organic-ship
> > feel as well.

sounds good; it might work by disrupting fire-control rather than the
beam
itself; whilst the direct mode might work against lasers, i feel it
would
be harder against particle beams.

> > (One of David Brin's books had a scene where a (non-bio) ship dumped
a
> > massive load of water to screen it's escape - and to lose the
> > wieght)(Can't remember the name...not 'Uplift War', not "sundiver',
one of
> > the other uplift series books...with dolphins in it...mental
blank...)

as someone pointed out, brin is a physicist, so we trust him on this
one.
on the other hand, frank tipler is a physicist, and he's written some
complete tosh. stephen baxter is an engineer, and 'moonseed' has gaps
the
size of intergalactic voids. this is probably why they call it 'science
fiction'.

Tom