HDTenEightyP/NetNews huggingface dataset:
From: artn@bert.eecs.uic.edu (Ellyn Sandor)
Newsgroups: rec.arts.sf.science
Subject: Mini-Atomics
Date: 4 Sep 92 21:45:45 GMT
Article-I.D.: bert.1992Sep4.214545.25904
Organization: University of Illinois at Chicago


	The book _Logan's Run_ refers to a "vestpocket a-bomb".  I have
heard that at present there are tank shells with atomic bombs, as well
as shells for battleship guns and small missles for aircraft.
	True or not?  Who cares.
	But... what is the minimum practical size of a fission or fusion
bomb?  The aforementioned projectile bomb is purported to vaporize about
one city block.  Is that realistic?  Can an atomic grenade be made, say
one to ten pounds, which can destroy a single building?  A few ounces
for a room?
	I've heard the stories from the 50s about "X pounds of uranium
or Y pounds of plutonium will start fission when brought together," such
as in the recent John Cusack movie ("Fat Man and Little Boy?")  I presume
at this point we have somewhat more elegant methods of controlling such
things.
	And should I cross-post this somewhere else?

			sm
-- 
--
Stephan Meyers | artn@uicbert.eecs.uic.edu
(Art)^n Laboratories, inventors of the Stealth Negative PHSCologram
(312) 567-3762
Newsgroups: rec.arts.sf.science
From: jbf@wts.com (Jens B. Fiederer)
Subject: Re: Niven's teleportation & 2nd law of thermodynamics (was: Superconductors + the 2
Organization: Wegmans Transaction Services
Date: Wed, 9 Sep 1992 14:55:36 GMT

In article <FRANCIS.92Sep3094741@galois.dogwood.atl.ga.us> francis@dogwood.atl.ga.us (John Stracke) writes:
>In article <1992Sep2.204731.4669@msc.cornell.edu> hillyard@msc.cornell.edu writes:
>
>>From article <1992Sep2.114236.428@cine88.cineca.it>, by campo@sunthpi3.difi.unipi.it (Massimo Campostrini):
>>[...]
>>>    Any comment on this? Maybe the 2nd law of thermodynamics is
>>> supposed to be "less fundamental" or "less established" than the
>>> 1st by non-physicists?
>>
>>It is less fundemental in the sense that it is a statistical law.  Entropy
>>can go down in a system--its just unlikely.
>
>Make that *extremely* unlikely.  Sufficiently unlikely that it
>probably has not occurred more than a handful of times in the history
>of the Universe to date.
>
It has happened innumerable times!!!  The trick is to choose VERY SMALL
SYSTEMS.  The larger the system, the more the laws of large numbers
predominate.

Jens
Newsgroups: rec.arts.sf.science
From: baylor@force.ssd.lmsc.lockheed.com
Subject: Re: Mini-Atomics
Reply-To: baylor@force.ssd.lmsc.lockheed.com
Organization: LMSC, Sunnyvale, California
Date: Wed, 9 Sep 92 19:40:58 GMT

In article <rwallace.715785120@unix1.tcd.ie>, rwallace@unix1.tcd.ie (russell wallace) writes:
>Basically a fission device requires a critical mass, and therefore a
>certain minimum amount of fissionable material. (Though you *can* reduce
>the explosive yield almost arbitrarily by making the bomb inefficient so
>that most of the material remains unfissioned.)
>
[other stuff deleted]
I've always wondered about the concept of "critical mass". The
explanation I've heard is that there has to be enough fissionable 
material so that there are good odds on a released particle from atomic
decay hitting another fissionable atom (which then releases other 
particles, which need good odds on hitting still other fissionable atoms).
Ok, so what if you had a "Perfect Partical Reflector?" Then no particles
would be lost, and most would eventually cause atoms to split. 
Would such a (mythical) substance destroy the concept of critical 
mass? (Kids! Amaze your friends with the ATOMIC CAP PISTOL!!)
Newsgroups: rec.arts.sf.science
From: dietz@cs.rochester.edu (Paul Dietz)
Subject: Re: Mini-Atomics
Organization: Computer Science Department University of Rochester
Date: Tue, 8 Sep 1992 19:13:58 GMT

In article <1992Sep8.162944.25894@lmpsbbs.comm.mot.com> johnmc@comm.mot.com (John McCash) writes:

>In article <1992Sep4.214545.25904@bert.eecs.uic.edu>, artn@bert.eecs.uic.edu (Ellyn Sandor) writes:

< scenarios. One of them mentioned that since a certain isotope of
< Californium is fissionable (sorry, don't remember which one), with a
< critical mass of approx.  three grams, in theory you could make a
...
< would be. As I hazily recall, the conversion efficiency of a fission
< warhead is about either 3% or 30%. This would mean that either 1 gram
< or .1 gram would be converted to energy. I think critical mass for
< plutonium is roughly 10kg, so for a regular 2 kiloton or so warhead
< you're converting either 3 or .3kg to energy. So, assuming these
< figures are correct, and they may not be, the explosive yield should
< be roughly equivalent to 1/3 ton of TNT.


Californium would be dicey to make into a bomb -- a solid lump of the
stuff would glow white hot from the decay heat -- but I have read
about a proposal to make curium-245.  This isotope can be bred from
the curium in thermal fission reactor waste; the proposal I saw was to
use 14 MeV neutrons in a fusion reactor blanket.  The critical mass is
supposed to be about 50 grams.  It has a halflife in the centuries, if
I recall correctly.

Yield can be computed as follows.  At at atomic weight of around 250,
a gram contains 4e-3 moles or about 2.4e21 atom.  Each nucleus, when
fissioned, liberates about 200 MeV, or about 3.2e-11 joules.
Therefore, completely fissioning one gram yields about 8e10 joules of
energy, or about 20 tonnes of TNT equivalent.  In any real explosion,
however, only a fraction of the nuclei will fission.  If 10%, then the
yield is about 2 tonnes TNT/gram.  The 50 gram mass liberates about
100 tonnes of TNT equivalent.

Spontaneous fission should be common enough in these higher isotopes
to make bomb design difficult, but perhaps there is some way to get
around that problem.

	Paul F. Dietz
	dietz@cs.rochester.edu
Newsgroups: rec.arts.sf.science
From: ingles@engin.umich.edu (Ray Ingles)
Subject: Re: Mini-Atomics
Date: Wed, 09 Sep 92 20:48:06 EDT
Organization: University of Michigan Engineering, Ann Arbor

In article <rwallace.716073011@unix1.tcd.ie> rwallace@unix1.tcd.ie (russell wallace) writes:
>In <1992Sep9.130719.6060@sctc.com> beede@sctc.com (Mike Beede) writes:
>
>>rwallace@unix1.tcd.ie (russell wallace) writes:
>
>>>Basically a fission device requires a critical mass, and therefore a
>>>certain minimum amount of fissionable material. (Though you *can* reduce
>>>the explosive yield almost arbitrarily by making the bomb inefficient so
>>>that most of the material remains unfissioned.)
>
>>This critical mass thing is not really true, is it?  As I understand
>>it, the problem is fission products escaping without causing further
>>fission. If that can be prevented, a chain reaction can take place in
>>any reasonable amount of material.  So, for instance, if I could
>>create something that reflected all neutrons, I might be able to have
>>a 1 gram fission bomb (if I could assemble it fast enough).  Is this
>>correct?
>
>Yes, but no such material exists. In a far-future sf scenario, you could
>assume one (e.g. "scrith", the Ringworld floor material, would probably
>do), but in that case why not just assume micro-fusion bombs which don't
>require a fission trigger?

 A: Niven actually had a "fusion field" that the Belter culture used...
it was basically a forcefield that reflected neutrons.
 
 B: It was my understanding (and *please* correct me if I'm wrong) that
a 'critical mass' *per se* is not necessary, only that you need to duplicate
in some region the conditions of a critical mass. I.e. if you compress
the material enough, there will be a good chance that a given neutron
will hit another atom, etc., etc.
 So, if you just surround a less-than-critical mass with enough explosives,
you can get a nuclear explosion. (Of course, "enough," most likely, would
be more than you'd get out of the fission reaction... right?)

>Russell Wallace, Trinity College, Dublin
>rwallace@unix1.tcd.ie

Sincerely,

Ray Ingles                  || The above opinions are probably
                            || not those of the University of
ingles@caen.engin.umich.edu || Michigan. Yet.
Newsgroups: rec.arts.sf.science
From: johnmc@comm.mot.com (John McCash)
Subject: Re: Mini-Atomics
Organization: Motorola Land Mobile Products Sector
Date: Tue, 8 Sep 1992 16:29:44 GMT

In article <1992Sep4.214545.25904@bert.eecs.uic.edu>, artn@bert.eecs.uic.edu (Ellyn Sandor) writes:
|> 	But... what is the minimum practical size of a fission or fusion
|> bomb?  The aforementioned projectile bomb is purported to vaporize about
|> one city block.  Is that realistic?  Can an atomic grenade be made, say
|> one to ten pounds, which can destroy a single building?  A few ounces
|> for a room?

I read a letter in Dragon Magazine a year or two ago in which the writers were
discussing possible "secret weapons" for use as plot hooks in spy adventure
scenarios. One of them mentioned that since a certain isotope of Californium is
fissionable (sorry, don't remember which one), with a critical mass of approx.
three grams, in theory you could make a nuclear 38 caliber bullet. Talk about
the ultimate handgun! Of course, using current technology, the material would
all have to be made in a particle accelerator, and would only have a half life
of a few weeks at best. Also, I'm not sure what the explosive yield of such a
weapon would be. As I hazily recall, the conversion efficiency of a fission
warhead is about either 3% or 30%. This would mean that either 1 gram or .1
gram would be converted to energy. I think critical mass for plutonium is
roughly 10kg, so for a regular 2 kiloton or so warhead you're converting either
3 or .3kg to energy. So, assuming these figures are correct, and they may not
be, the explosive yield should be roughly equivalent to 1/3 ton of TNT.
								John
Newsgroups: rec.arts.sf.science,rec.arts.sf.written
From: rwallace@unix1.tcd.ie (russell wallace)
Subject: Re: Something Nasty in the Human Genome
Organization: Trinity College, Dublin
Date: Mon, 14 Sep 1992 11:28:07 GMT

In <1992Sep13.043751.21009@ultb.isc.rit.edu> smt1179@ritvax.isc.rit.edu (Tom Thatcher) writes:

>In article <rwallace.716203570@unix1.tcd.ie>, rwallace@unix1.tcd.ie (russell wallace) writes:
>>In <1992Sep10.212615.768@csc.canterbury.ac.nz> chisnall@cosc.canterbury.ac.nz (The Technicolour Throw-up) writes:
>>
>>>From article <1992Sep8.094119.26816@crc.ac.uk>, by gwilliam@crc.ac.uk (Gary Williams x3294):
>>>>>In article <1992Sep3.031844.21399@news.eng.convex.com>, cash@convex.com (Peter Cash) writes:
>>>>>Hmmm. I read an article in my local newspaper a few days ago that claimed
>>>>>that several research teams have found a "fractal pattern" in the "junk"
>>>>>DNA of many diverse lifeforms, including man. (According to one team, the
>>>>>fractal complexity was highest for man, according to the other, it wasn't.)
>>
>>Yes, but wouldn't you naturally expect to find fractal sequences in the
>>junk DNA? After all, the junk DNA is formed not by random nucleotides
>>getting appended one by one, but by the duplication (and subsequent
>>modification) of segments of DNA of various sizes. Hence you would

>You are making a questionable assumption with the use of the word "junk"
>to describe DNA that we still have after 3 billion years of evolution.
>"Selfish Gene" theory holds that life is just DNA's way of making more DNA.
>Just because we don't know what some DNA does doesn't mean it does nothing.
>At the very least, it has done a very good job of keeping itself around,
>which is the whole point, from the DNA point of view.

What makes you think that any particular sequence of junk DNA has been
around for any length of time? I would imagine that any particular
sequence of it would be quite rapidly altered by genetic drift (since it
does nothing, and is therefore not preserved by selection) - although,
to be sure, the fact of the existence of some junk DNA has been around
for a very long time.

And if you think it actually does anything to preserve itself, then
what? This is the first time I've heard the idea mentioned.

--
"To summarize the summary of the summary: people are a problem"
Russell Wallace, Trinity College, Dublin
rwallace@unix1.tcd.ie
Organization: Penn State University
Date: Tue, 8 Sep 1992 10:05:33 EDT
From: <EXE101@psuvm.psu.edu>
Newsgroups: rec.arts.sf.science
Subject: Re: Laser weapons
 <FRANCIS.92Sep3154408@galois.dogwood.atl.ga.us>
 <rwallace.715604300@unix1.tcd.ie> <NICKH.92Sep7141331@VOILA.VENARI.CS.CMU.EDU>
 <rwallace.715944724@unix1.tcd.ie>


Following along the sonic weapon thread:

    I've read at one time or another that various sound waves can be quite
powerful.  In one experiment I heard of they used sound waves to levitate
objects.  In another experiment they used sound waves to punch shaped holes
through various materials.  I believe some of these materials where metal.
I've forgotten the exact details but seems to me that there might be some
potential in a directional sonic weapon.

                                                           2
                                                          E



"Silicon Songs play harshly in my head."
itself in the memory of a computer."

Mamir BaBu
Newsgroups: rec.arts.sf.science
From: rwallace@unix1.tcd.ie (russell wallace)
Subject: Re: Laser weapons
Organization: Trinity College, Dublin
Date: Tue, 8 Sep 1992 09:32:04 GMT

In <NICKH.92Sep7141331@VOILA.VENARI.CS.CMU.EDU> nickh@CS.CMU.EDU (Nick Haines) writes:

>In article <rwallace.715604300@unix1.tcd.ie> rwallace@unix1.tcd.ie (russell wallace) writes:

>   In <FRANCIS.92Sep3154408@galois.dogwood.atl.ga.us> francis@dogwood.atl.ga.us (John Stracke) writes:

>   >Possibly sonics (anybody know feasibility here?).

>   Not very; it's the same as lasers, you simply can't get enough power
>   output. Also there's no way to keep the sound in a tight beam. (Though
>   one weapon I did use in an sf scenario was a sonic stunner that was like
>   a directional version of the stun grenades used by anti-terrorist teams;
>   it produces a very intense blast of sound that will shock anyone within
>   a few metres in a 60 degree arc into immobility. Not a general-purpose
>   weapon, but a nice touch I thought.)

>But there was that court case in Britain a few years ago of a bloke
>who'd built a sonic `projector' to rig a horse race by distracting the
>lead horse. Definitely directional.

Oh, you can *distract* with sonics all right, you just can't do any
damage. (Imagine: you send your troops into battle armed with the latest
in high-tech weaponry, the fearsome Mark 1 Portable Stereo System :-).)


--
"To summarize the summary of the summary: people are a problem"
Russell Wallace, Trinity College, Dublin
rwallace@unix1.tcd.ie
From: urf@icl.se (Urban F)
Newsgroups: rec.arts.sf.science
Subject: Rocket projectiles (Was: Re: Laser weapons)
Date: 5 Sep 92 05:41:13 GMT
Organization: None. On USENET I speak only for myself.
X-Alt.reply-Address: n.g.u.fredriksson.swe2001@oasis.icl.co.uk

rwallace@unix1.tcd.ie (russell wallace) writes:

>Main problem with rocket-propelled projectiles is that they will be very
>much slower than bullets. You could use a small explosive warhead, but
>experience with tanks has shown that composite armor can defeat
>shaped-charge warheads much easier than it can defeat high-velocity
>solid slugs; this might scale down to personal armor.

Rockets doesn't have to be slower, but if you have a light, very fast
projectile, it will lose speed at a greater rate than a slower, heavier.
For armour penetration, you'll want it to be very fast when it reaches
the target, so why not emulate runway-busters: Ignite the motor close
before impact.
-- 
 Urban Fredriksson   urf@icl.se
Newsgroups: rec.arts.sf.science
From: tmyoung@rodan.acs.syr.edu (Thomas M. Young)
Subject: Re: Niven's teleportation & 2nd law of thermodynamics (was: Superconductors + the 2
Organization: Syracuse University, Syracuse, NY
Date: Fri, 4 Sep 92 09:20:23 EDT

In article <1992Sep2.204731.4669@msc.cornell.edu> hillyard@msc.cornell.edu writes:
>From article <1992Sep2.114236.428@cine88.cineca.it>, by campo@sunthpi3.difi.unipi.it (Massimo Campostrini):
>[...]
>>    Any comment on this? Maybe the 2nd law of thermodynamics is
>> supposed to be "less fundamental" or "less established" than the
>> 1st by non-physicists?
>
>It is less fundemental in the sense that it is a statistical law.  Entropy
>can go down in a system--its just unlikely.
>
>SEH

But doesn't quantum mechanics ensure that it can't go down?  It was my
understanding that, at least using Shroedinger's Equation, you are 
guaranteed non-decreasing entropy because of the state mixing.  Does 
this depend on which philosophy of q.m. you subscribe to?


--
Tom Young                                         tmyoung@rodan.acs.syr.edu
Newsgroups: rec.arts.sf.science
From: wengland@stephsf.com (Bill England)
Subject: Book Review: 2020 Vision (Re: Future Civilization Advances)
Date: Thu, 10 Sep 1992 02:03:46 GMT
Organization: Stephen Software Systems Inc., Tacoma/Seattle, +1 800 829 1684
X-Bytes: 1696

Good Timing! (again)

I just finished reading "2020 Vision" by Stan Davis and Bill Davidson.
This is a very good book thats frames human progress  in terms of 
economic advances.

Currently Stan sees us entering the "Age of smart toilets" or the
hayday of the new information economy.  Many premises are demonstrated
and put forward in the book and predictions are made as to how our next
economy, the bio-economy will unfold. 

All in all it's a  riveting book that will make you review your current
business practice in light of the rapidly aging info-economy.  Lights
were going on for me all over the place.

It becomes clear in this book that it isn't simply inventions that
cause advancment but, economic shifts based on competition.  In this
case it is not the discovery of DNA than changes the world but, the
creation of Nano machines that can manipulate it to our will.

Summary

I had originally bought the book for research  into my software
development business but have instead added it to my "reality is
more interesting than Sci-Fi collection."

PS.
   The question has been proposed ... "Would you buy a `Mind Machine'?
   Stan thinks not today but, such things will be essential in 30 years.

  (Also, I really would like to go to Saturn ...  if you can get
   funding I'll  help design/write the systems software ... See previous
   book review for context. )

-- 
 +-  Bill England,  wengland@stephsf.COM -----------------------------------+
 |   * *      H -> He +24MeV                                                |
 |  * * * ... Oooo, we're having so much fun making itty bitty suns *       |
 |__ * * ___________________________________________________________________|
From: trip@cco.caltech.edu (Trip)
Newsgroups: rec.arts.sf.science
Subject: Re: Rocket projectiles (Was: Re: Laser weapons)
Date: 9 Sep 92 08:38:38 GMT
Organization: California Institute of Technology, Pasadena

rwallace@unix1.tcd.ie (russell wallace) writes:

>Main problem with rocket-propelled projectiles is that they will be very
>much slower than bullets. You could use a small explosive warhead, but
>experience with tanks has shown that composite armor can defeat
>shaped-charge warheads much easier than it can defeat high-velocity
>solid slugs; this might scale down to personal armor.

Not only are rockets slower than bullets (presuming equal masses of
propellant and warload), but rockets are slowest (hence, least
effective) near the muzzle, which
is where you want handguns and submachine guns to be *most* lethal.

My understanding is that explosive projectiles are not terribly
effective against people. 'Explosive bullets' are more like superduper
hollowpoints; the explosive breaks them up so they deposit the energy of
the bullet more unpleasantly, but the energy of the explosive is much
less than that of the bullet. Shaped charges are designed to punch
through armor, so they would just poke narrow holes through people.
Dangerous, but not an optimum use of your explosives.

I suppose you could put a rocket booster on a bullet to extend the
range, but firearms already throw bullets farther than they could
possible be accurate.

Trip				|   Never stay a minute too long
President, ECNG			|   Don't forget the best will go wrong
(trip@cobalt.cco.caltech.edu)	|   Nobody's on nobody's side
				|			-_Chess_
From: swf@teradata.com (Stanley Friesen)
Newsgroups: rec.arts.sf.science
Subject: Re: Mini-Atomics
Date: 11 Sep 92 22:43:16 GMT
Reply-To: swf@tdat.teradata.com (Stanley Friesen)
Organization: NCR Teradata Database Business Unit

In article <18nk0gINN1b9@usenet.INS.CWRU.Edu> be726@cleveland.Freenet.Edu (Joseph A. Ellis Jr.) writes:
|
|You know, I would think a LONG time before I fired that bullet... 

Agreed.

|It reminds me of the "Atomic Hand Grenade" in the 'Paranoia' game. I don't
|recall the exact numbers, and they're not really important... but it had a
|burst radius of something like 40 meters... and the thrown range of it was
|_30_ meters!

Hmm, that sounds an aweful lot like a *real* hand grenade.
[When they say 'throw it and DUCK', they mean it].
-- 
sarima@teradata.com			(formerly tdatirv!sarima)
  or
Stanley.Friesen@ElSegundoCA.ncr.com
Newsgroups: rec.arts.sf.science
From: beede@sctc.com (Mike Beede)
Subject: Re: Mini-Atomics
Organization: SCTC
Date: Wed, 9 Sep 1992 13:07:19 GMT

rwallace@unix1.tcd.ie (russell wallace) writes:

>Basically a fission device requires a critical mass, and therefore a
>certain minimum amount of fissionable material. (Though you *can* reduce
>the explosive yield almost arbitrarily by making the bomb inefficient so
>that most of the material remains unfissioned.)

This critical mass thing is not really true, is it?  As I understand
it, the problem is fission products escaping without causing further
fission. If that can be prevented, a chain reaction can take place in
any reasonable amount of material.  So, for instance, if I could
create something that reflected all neutrons, I might be able to have
a 1 gram fission bomb (if I could assemble it fast enough).  Is this
correct?

	Mike


-- 
Mike Beede         Secure Computing
beede@sctc.com     1210 W. County Rd E, Suite 100           
------------------ Arden Hills, MN  55112
                    (612) 482-7420
Newsgroups: rec.arts.sf.science
From: wiml@milton.u.washington.edu (William Lewis)
Subject: Re: Niven's blunders (was:Superconductors + the 2nd law)
Organization: University of Washington, Seattle
Date: Mon, 7 Sep 1992 05:49:56 GMT

In article <8-ty74#@rpi.edu> kasprj@rpi.edu writes:
> The problem is that, once the ship leaves the vicinity of the neutron
>star, it's got all that angular momentum impatred to it by the torque 
>of being swung around perpendicular to the neutron star's surface. There's
>no way to get rid of that angular momentum quickly, so Shaeffer still has
>the problem of being flung towards one end or the other of his ship (though,
>for what it's worth, this time he knows the source of the acceleration (-:).
>Sooner or later he's going to lose his grip there at the center of the ship
>and... *splat*. 

  Even given attitude jets and big momentum wheels? (For that matter,
maybe even the "reactionless drive"? I don't remember when that
was supposed to be invented.) Remember, one of the things he put
on the ship was a "very large" fusion drive, which I would assume
would translate also to a "very large" attitude jet. At one point
he tried to force the ship out of the tidally locked orientation,
so he must have attitude control with some oomph to it...


-- 
email: wiml@u.washington.edu             |  Home:  Seattle, Washington   |
     (William Lewis)                     |  47 41' 15" N   122 42' 58" W | 
NeXTmail: wiml@ingalls.cs.washington.edu `-------------------------------'
        --*-- Member, Coalition to Preserve Semantic Vacuity --*--
Newsgroups: rec.arts.sf.science