On Mar 6, 9:44 am, CharlesRCap...@[EMAIL PROTECTED]
wrote:
> On Mar 5, 9:24 pm, John Schilling <schil...@[EMAIL PROTECTED]
> wrote:
>
> > On Tue, 4 Mar 2008 08:35:26 -0800 (PST), CharlesRCap...@[EMAIL PROTECTED]
> > This being rec.arts.sf.science, we can talk about the consequences if
> > someone were to imagine up such a material as the One Impossible Thing
> > allowed in their SF story, or we can explain why it actually is an
> > impossible thing. Which would you prefer?
>
> Well, there is a difference between unobtanium and handwavium. The
> latter is impossible when considered with our current understanding,
> the former is not impossible but no one can think of a way to do it.
> Which may mean that it IS impossible, but it gives the author more
> wiggle room. Handwavium must be strictly regulated lest a story become
> unbelievable, and is proscribed for the so called "hard" science
> fiction. Unobtanium has a lower "cost" in believability, particularly
> if the author provides a good explanation and relies on a chain of
> technology that is at least plausible if not probable. Now I'm sure
> you already knew this, so I'm just stating it for the record.
>
> Now as for the question you asked, I am looking for unobtanium (not
> impossible just unobtainable with current tech and/or scientific
> understanding) rather than handwavium (impossible given current
> understanding of science, but allowable if the author gives a vague
> enough explanation, a "hand wave" as it were, and makes the assumption
> that the reader will play along) so in this case, the explanation of
> why it really is impossible would be the preferred route.
>
> If reduced mass radiation shielding moves from unobtanium to
> handwavium, then I must thus discard it if I wish to remain "hard" in
> my science fiction.
>
> Now, I'm not expecting to reduce the mass needed for radiation
> shielding to negligible status, though any reductions in mass would be
> welcome. If for no other reason than I don't have to explain to the
> reader that the hull is lined with lead, when I could explain that it
> is lined with a high tech composite that works some small amount
> better than just lead.
>
> Luke did mention some things that help from a narrative standpoint, he
> reminded me that the reaction mass of the ship is quite able to
> provide protection from the engine/powerplant's radiation, which is
> good since if you run out of reaction mass, then there isn't much need
> to run the engine/powerplant. He also pointed out my confusion on the
> differences between neutron and gamma radiation.
>
> Robert hit dead on the point I was trying to get at, which is that how
> much does random placement of atoms in a material "waste" the
> protection of atoms that are shadowed? I'm guessing not much, but a
> small amount. Perhaps a crystal form of a heavy metal might perform
> better if its "tunnels" are arranged to be perpendicular to the angle
> that must be protected. (Not necessarily arranged in a two dimensional
> plane but perhaps a crystal structure designed to minimize the number
> of shadowed atoms.) However I get the feeling by responses that this
> method would be unlikely to generate any kind of reasonable reduction
> in mass for the cost of manufacture.
>
> So perhaps a composite material that takes advantage of the way that
> neutron radiation causes byproducts. Perhaps a material made up of
> alternating layers of heavy metals and hydrogen bearing materials
> might be more effective on a mass basis than just masses of metals or
> hydrogen alone. Actually I seem to remember something like that being
> proposed in the past, but I don't remember the specifics of the
> debate.
Why do you need the shielding effect anyway? Is it just to protect
the crew and passengers? If so, why not just posit some sort of
advanced medicine?
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