From: gt1759c@prism.gatech.EDU (Donald Morris)
Newsgroups: rec.arts.sf.science
Subject: Re: A nuclear question...
Date: 28 Sep 92 17:37:24 GMT
Organization: Georgia Institute of Technology/NE Student

In <6400@blue.cis.pitt.edu.UUCP> seawasp@vm2.cis.pitt.edu (Sea Wasp) writes:

>	Here's a question that pertains somewhat to SF:

>	I've seen it written many times (in stories, popular articles,
>etc) that at the time of the first atomic bomb test there were some
>respected scientists who were of the considered opinion that detonating
>the  Bomb could cause a self-sustaining nuclear chain  reaction
>(Which would either then just sit there and glow in atomic brilliance
>for eternity, or propogate across the world and blow it to pieces).

Hmm.... I don't remember this being said about the first fission bombs. There
was a _lot_ said in this line before the first fusion bomb tests. I'll say more
on this in a moment..... I suppose, though, they could have been worried about
such an intense neutron flux from the detonation that fission of usually non-
fissile materials could occur. In other words, the probablility (cross-section)
of most materials capturing a neutron and fissioning as a result is quite low.
And I mean _low_. You have a better chance of getting a spontaneous fission
of a U-235 atom. Since I don't remember offhand how much cross-section 
determination experimentation had occurred pre-1944, they might not have known.

>	This is really a two part question -- first, is this true --
>that there were some eminent and competent experts who held these
>views?

Could be. See above for why. I _know_ that there were a TON of people worried
before the first fusion bomb detonation. Why is next...

>	Second, and more to the SF point -- was there, AT THAT TIME,
>good reason to hold that view? In other words, was the fact that 
>nuclear chain reactions of the sort they feared could not happen
>something that COULD NOT have been known at that time -- that could
>only be known through research done later?

As a said before, I was under the impression that they should have known
better at the time. I mean, how can you do effective plutonium production
without knowing fission and absorption cross sections? At any rate, its 
certainly possible. As far as fusion, however, they _didn't_ know, they were
just pretty sure about the theories they had. The added insecurity was due to
the high concentration of hydrogen (water, gaseous, etc.) and the corresponding
supplies of deuterium and tritium. In other words, quite a few people thought
that once you got the fusion reaction started, the heat and pressure waves 
would be sufficient to induce secondary and tertiary fusion reactions, which
would be enough to induce still _more_ reactions until the Earth became a cute
little mini-sun for a while before becoming just a cinder. What the prevailing
scientists (and the people who built the damn thing) said was that the fuel
concentrations (no where near primary levels, since you seed the bomb for
the fusion reaction) and the expanding sphere of heat and pressure (causing
less intense effects with distance) would keep the secondary and tertiary, etc.
reactions from being intense enough to maintain a chain reaction. And they
were right (thank goodness...) ;)

>	As a corollary to this -- in view of the answers to the
>above questions, is it possible from an SF standpoint to have
>a scientific advance whose science is sufficiently understood to
>produce a desired engineering result -- a device based on this new
>principle -- but whose science is at the same time so LITTLE understood
>that the device could have any one of several radically different
>outcomes upon operation? Or is the apparent existence of this condition
>in the atomic bomb case just a sort of intellectual illusion -- that
>is, that those who held that view were ignoring inarguable, complete
>proof that their views were wrong?

I certainly think its possible, especially given the fact that weapons research
concentrates heavily on results. In other words, if you get a desired effect
in a lab, the Pentagon will probably have you build something to try to 
amplify the effect even before its completely understood. The A-bomb doesn't
fit in my mind, since I still _think_ most people should have known cross
sections well enough, but these are the same people that stood beside an
unshielded reactor below the Chicago University football stands.....*cough*

>	(This train of thought was started while re-watching an episode
>of Ren & Stimpy: the "History Eraser Button" -- Stimpy: "So... what'll
>happen?"  Ren(crazed):"That's just it! WE DON'T KNOW! Mayyyybe something
>bad.... mayyybe something good!..."   (From the episode "Space Madness"))

Ren & Stimpy, fathers of the Second Technological Revolution... >:)
	"Happy, happy..... joy, joy!"

Donald Morris                         Box 24815 Ga. Tech Station
vapspze@prism.gatech.edu              Atlanta, GA 30332
====================================================================
"Give me life, give me pain, give me myself again..."
			-Tori Amos, _Little Earthquakes_

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