HDTenEightyP/NetNews huggingface dataset:
From: 2frssprout@kuhub.cc.ukans.edu
Newsgroups: rec.arts.sf.science
Subject: Kevlar balloon space stations
Date: 14 Apr 92 08:44:33 CDT
Organization: University of Kansas Academic Computing Services

Whatever happened to the idea of using Kevlar and Kevlar-like
materials in balloon-type structures in a space station?  

It seems to me that if we put together a large kevlar balloon with
many chambers, filling each part with rigid, but light, structures
that people would actually walk around in (erector set pieces, not
launched within the balloon, carried up separately & assembled)?

From what I understand, if Kevlar sustains an injury, say, a puncture
hole, it merely starts leaking through that small hole, as opposed to
the rubber balloon tendancy to explosively rend/tear/shear.   Could
someone from DuPont correct me on this?  

Yes, I understand the psychological factor here, but the only people
we need worry about are the astronauts, right?

Also: are there radiation problems with Kevlar that aluminum or
titanium or steel or (grin) rolled iron (whatever we use as materials
for the walls of our space structures) doesn't have?
From: egl1@cunixf.cc.columbia.edu (Elizabeth G. Levy)
Newsgroups: rec.arts.sf.science
Subject: Re: Psychohistory
Date: 10 Apr 92 23:07:13 GMT
Reply-To: egl1@cunixf.cc.columbia.edu (Elizabeth G. Levy)
Organization: Columbia University

In article <1992Apr09.160916.14693@onetouch.COM> csmith@onetouch.COM (Craig Smith) writes:
>I have a major gripe with Foundation's Psychohistory.
>
>It is based on the gas laws, which say that while the actions of a single
>atom are not predictable, a large enough quantity of gas is highly predictable.
>Asimov took this and applied it to people to make pychohistory.
>
>The problem is, that every major turning point was predicted by Harry Seldon,
>but the actual change was accomplished, not by masses of humanity, but
>by a single person!

Asimov's argument would have been that these people are not
transcendental figures.  They do not define history.  Instead,
people rise up to fit whatever roles are necessary for that history.
The argument would have been that Hitler or Napoleon would be
inevitable figures.  If not Hitler, then some other figure filling
the same role.
Newsgroups: rec.arts.sf.science
From: jon@cyclone.MITRE.org (J. E. Shum)
Subject: Re: Psychohistory
Originator: jon@cyclone
Organization: The MITRE Corp. McLean Va.
Date: Fri, 10 Apr 1992 19:40:07 GMT


In article <1992Apr09.160916.14693@onetouch.COM>, csmith@onetouch.COM (Craig Smith) writes:
> I have a major gripe with Foundation's Psychohistory.
> 
> It is based on the gas laws, which say that while the actions of a single
> atom are not predictable, a large enough quantity of gas is highly predictable.
> Asimov took this and applied it to people to make pychohistory.
> 
> The problem is, that every major turning point was predicted by Harry Seldon,
> but the actual change was accomplished, not by masses of humanity, but
> by a single person!
> 
> Now, while following the actions of a mass of people does not make for
> a good story, he contradicts the main point the the series by doing
> this.
> 
> Actually, if we look at history as we know it now, at the center of every
> major event in history stood a single person, not a mass of people.
> 
> Any refutations? comments?
> 

The only thing I can refute is what you claim Asimov said Psychohistory
was.  (Gad what a sentence.  Glad my 8th grade english teacher can't
see it)  Actually the point you make about the individual's importance
in history is confirmed in _Foundation and Empire_ and _Second Foundation_.

The leader of the Second Foundation makes the point rather strongly that
the plan had to be constantly revised to remain current.

-- 

<jon@mitre.org>
From: jc@crosfield.co.uk (jerry cullingford)
Newsgroups: rec.arts.sf.science
Subject: Re: Cherryh's technology (Docking)
Date: 16 Apr 92 12:21:40 GMT
Reply-To: jc@crosfield.co.uk (jerry cullingford)
Followup-To: rec.arts.sf.science
Organization: Crosfield Electronics, Hemel Hempstead, United Kingdom.

In article <1992Apr14.041927.16381@ccu1.aukuni.ac.nz> ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig) writes:
>>C. J. Cherryh's _Downbelow Station_ includes some strange physics:
>
>> - Long, narrow spaceships hanging sideways by the nose at the edge
>>   of a spinning space station.
>
>What's strange about that?

Well, it's a hideously messy, dangerous, and fuel-expensive method of docking.
The stations spin to give (presumably) the equivalent of a 1g field at the
docking level. That means that the ships must be capable of accelerating at
more than 1g perpendicular to their long axis, or they'd never be able to
dock in the first place.

Given that they apparently use normal reaction propulsion systems for this,
that is one hell of a lot of reaction mass to spend for something the size
of 'Dublin' or 'Norway'.

It would also require a very strong ship structure to support the weight of
the entire ship, and the leverage of the long axis.. Not to mention the
stresses on the docking point.

And screw up matching the stations rotation and you hit/get hit by one
-- 
+-----------------------------------------------------------------+     |
| Jerry Cullingford  #include <std.disclaimer>     +44 442 230000 |   ,-|--
| jc@crosfield.co.uk (was jc@cel.co.uk) or jc@cel.uucp      x3868 |   \_|__
+-----------------------------------------------------------------+ \___/
Newsgroups: rec.arts.sf.science
From: kempga@NeXTwork.Rose-Hulman.Edu (Greg Kemp)
Subject: Re: Dyson Sphere
Reply-To: kempga@NeXTwork.Rose-Hulman.Edu
Organization: Rose-Hulman Institute of Technology
Date: Thu, 9 Apr 1992 14:59:47 GMT

Reading about Dyson Spheres made me wonder:

Suppose, in a fit of industriousness, we were to build a Dyson Sphere  
around the sun to really capitalize on solar energy.  How would we deal  
with the solar wind?

I'm missing one key piece of information: the amount of material the sun  
throws off per square meter of solar surface.  Maybe this solar wind  
business is not worth considering, but I can't help but wonder.

--
Greg Kemp
inmate, Rose-Hulman Institute of Technology
Terre Haute, IN
Internet: kempga@nextwork.rose-hulman.edu
From: tbmg9061@uxa.cso.uiuc.edu (Thomas B MacIukenas)
Subject: Re: Strength of skrith (sp?)
Organization: University of Illinois at Urbana
Date: Tue, 14 Apr 1992 03:20:00 GMT


ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig) writes:

>First, let's figure out what force the floor is submitted to:

>Let's define the mass density per lenght unit as M, the radius of the
>Ringworld as R, the acceleration on the floor as a.  Doing a bit of
>work (Hint: cut free, for example, a quarter of the Ringworld, then
>integrate over the centrifugal forces in the x - direction and set
>them equal to the resulting force in the other direction), we find
>that F = a * M * R

Are you sure R should be there?  If a is the _downward_ acceleration
on the floor, then I get the force to be  F = a * M, where M is the
mass of the floor-plus-everything-above-it.  What am I missing?  Why
did you need to include the R factor?
-- 
___-Tom_Maciukenas_(tbmg9061@uxa.cso.uiuc.edu)_________________________________
main(){char c[159],s[159]="main(){char c[159],s[159]=@@@;strcpy(c,s);s[26]=34;s
[27]=0;s[28]=34;printf(s);printf(c);puts(&s[28]);}";strcpy(c,s);s[26]=34;s[27]=
0;s[28]=34;printf(s);printf(c);puts(&s[28]);}
From: lizi@ocf.berkeley.edu (Cosma R. Shalizi)
Newsgroups: rec.arts.sf.science
Subject: Re: Those funky mushroom planets
Summary: Don't be photocentric
Date: 9 Apr 92 00:01:09 GMT
Article-I.D.: agate.s01g5INNoan
Organization: Vampire Research Group at Berkeley :)
NNTP-Posting-Host: avalanche.berkeley.edu

In article <1992Mar20.002903.8842@rigel.econ.uga.edu> hughes@dogwood.botany.uga.edu (wayne) writes:
>In article <92079.084149IOR@SLACVM.SLAC.STANFORD.EDU> IOR@SLACVM.SLAC.STANFORD.EDU (Thomas Hyer) writes:
>> [sensible & ugly questions about how an anaerobic-only ecosystem, e.g.
>>  just fungi, could be set up. Where's the energy come from?]
> ...there has to be some kind of autotrophic
>   form (such as photosynthetic bacteria) for saprophytes to munch on.
   Quite true, but not all autotrophs are photosynthetic. The ecologies of
those neat deep-sea vents are supported by bacteria which get energy from
metabolizing sulfur compounds, and I seem to recall from high school
microbiology that there are some which can pull the same trick with iron
compounds, though that may be just terminal post-midterm brain-fry. No
doubt an ingenious chemist could come up with more sources of energy.
   The other alternative is that the "primordial soup" is still sloshing
around, full of nice hydrocarbons & such just begging to be catabolyzed.
Not having read either of the stories in the original post, I couldn't say
if this is an option.
Cosma Rohilla Shalizi (lizi@ocf.berkeley.edu to friends)
Aspiring physicist who took microbio lo, these many years ago, and is quite
possibly talking out of his ass, & VP of the Campus Crusade for Cthulhu,
for which I DO speak.
"Disrepent now or be eaten alive by shoggoths!"
"For friends, anything. For enemies - the law!" - my grandfather
Newsgroups: rec.arts.sf.science
Subject: Re: Strength of skrith (sp?)
From: ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig)
Date: Tue, 14 Apr 1992 04:06:15 GMT
 <NICKH.92Apr8152110@VOILA.VENARI.CS.CMU.EDU> <1992Apr13.064543.20533@ccu1.aukuni.ac.nz> <1992Apr14.032000.14335@ux1.cso.uiuc.edu>
Organization: University of Auckland, New Zealand.

tbmg9061@uxa.cso.uiuc.edu (Thomas B MacIukenas) writes:

>ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig) writes:

>>First, let's figure out what force the floor is submitted to:

>>Let's define the mass density per lenght unit as M, the radius of the
>>Ringworld as R, the acceleration on the floor as a.  Doing a bit of
>>work (Hint: cut free, for example, a quarter of the Ringworld, then
>>integrate over the centrifugal forces in the x - direction and set
>>them equal to the resulting force in the other direction), we find
>>that F = a * M * R

>Are you sure R should be there?  If a is the _downward_ acceleration
>on the floor, then I get the force to be  F = a * M, where M is the
>mass of the floor-plus-everything-above-it.  What am I missing?  Why
>did you need to include the R factor?

That's what you get when you make a claim like that on the net without
offering proof :-)

All right, let's do it.

Let phi be the angle (in radians) from the centre of the Ringworld,
d l the infinitesimal length of a single piece we're looking at.
It then holds that 

d l = R * d phi

(which is why radians were introduced in the first place).

The centrifugal force, with mass density per length unit M and centrifugal
acceleration a, is then

d F = a * M * d l

This force is directed away from the Ringworld's centre.  So, only a
fraction of it contributes in any given direction, let's say the
x - direction, namely:

d Fx = a * M * cos(phi) * d l 

Seeing that d l = R * d phi, we arrive at

d Fx = a * M * cos(phi) * R * d phi.

If we want to know the resulting force of one quarter of the Ringworld,
we have to integrate over it (one quarter circle is pi/2 in radians),
so we get

     pi/2     pi/2
     I        I
Fx = I d Fx = I a * M * R * cos(phi) * d phi = a * M * R
     I        I
     0        0

with the three I's denoting an integral sign.

Hope I haven't confused most people here, with this :-)  It's non-
obvious if you are not used to thinking in differentials, I have to admit.
Sorry for using M for kilograms per metre, BTW, but the limitations of
ASCII formulas :-)
-- 
Thomas Koenig, ecmtwhk@ccu1.aukuni.ac.nz
Snail-Mail: 
c/o Department of Chemical and Materials Engineering, University of Auckland,
Private Bag 92019, Auckland, New Zealand
Newsgroups: rec.arts.sf.science
From: csmith@onetouch.COM (Craig Smith)
Subject: Re: How far is a second ?
Organization: MCS/OneTouch, Inc.
Date: Mon, 06 Apr 92 20:08:08 GMT

I still think that the same unit can be used for both space and time.
This was one of my main arguments for being able to set c=1 in the
first place.

-- 
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
::Craig Smith                                             csmith@onetouch.COM::
::Columbus, OH                                      ...!uunet!onetouch!csmith::
::"Life is a fulltime occupation."--Gene Kalman                              ::
Newsgroups: rec.arts.sf.science
From: mvp@hsv3.uucp (Mike Van Pelt)
Subject: Re: Kevlar balloon space stations
Organization: Video 7 + G2 = Headland Technology
Date: Wed, 15 Apr 1992 00:37:06 GMT

In article <IdulRl_00UhWI44qto@andrew.cmu.edu> James William Stepanek <js43+@andrew.cmu.edu> writes:
>>Also: are there radiation problems with Kevlar that aluminum or
>>titanium or steel or (grin) rolled iron (whatever we use as materials
>>for the walls of our space structures) doesn't have?

>Well Kevlar would provide no shielding whatsoever against
>electromagnetic ratiation and other forms of radiation above alpha
>particles.

Actually, with cosmic rays, no shielding at all is better than 
inadequate shielding.  Adequate shielding means something like
14 pounds of shielding per square inch of external surface area.
(That's the shielding we have here at sea level.)

The problem with "a little but not enough" shielding is that the
cosmic ray primaries, which would otherwise mostly just pass right
on through without doing a whole lot of damage, get converted to
a shower of very damaging secondary particles.

So what you'd really like to do is coat your space station with
about three feet of lunar dirt.  (This is much more of a problem
outside the Van Allen belts than in low earth orbit, though.)

>Also polymers have a tendency to break down under UV radiation,
>which happens to be mych more intense in space due to a lack of
>ozone shielding.

This is the main problem.  You could probably coat the kevlar with
something UV-reflecting, though.
-- 
Mike Van Pelt                     Will your long-winded speeches never
Headland Technology/Video 7       end?  What ails you that you keep on 
...ames!vsi1!hsv3!mvp             arguing?    --    Job 16:3
mvp@hsv3.lsil.com
Xref: sparky rec.arts.sf.science:1429 alt.cyberpunk.tech:345 alt.cyberspace:228
From: wengland@stephsf.com (Bill England)
Newsgroups: rec.arts.sf.science,alt.cyberpunk.tech,alt.cyberspace
Subject: Re: Virtual reality, the brain, and high-speed modems.
Date: 10 Apr 92 21:16:26 GMT
Organization: Stephen Software Systems Inc., Tacoma/Seattle, +1 800 829 1684
X-Bytes: 2417

In article <1992Apr7.160153.13146@ux1.cso.uiuc.edu> mjg51721@uxa.cso.uiuc.edu (Michael James Gebis) writes:
>I have recently read a variety of stories concerning COMPLETE virtual reality..
>where the user has had an implant (or something, sometimes this is not very
>clear) in his brain which totally simulates all sensory input, and also receives
>all commands from the brain.
>My question is....how much information is this?  How fast an interface would be
>required?  Would a simple parallel port do, or are fiber-optics more realistic?
>Anyway, thanks.
>


  Interface?  To your Brain?  A parallel port?  Well _kind_ of
  parallel, actually VERY parallel ...  :-)

----

  INTRODUCING THE GNU DO IT YOURSELF BRAIN AUGMENTATION KIT!

  Are you tired of your old VR helmet? Is your data glove
  touch feedback just not fast enough? Is the new Sco OS for 
  these systems still 4 releases behind everyone else? 

  Cut out the middle man!  Spend no more money on high priced
  equipment that only takes you half way there! Go all the way 
  and permanently embed yourself in Cyberspace with ...

  -----
  The GNU DIYBAK 

  1)  Included are two complete, and replicateable nano factorys
      with 50,000 Nanos ready to go to work on you.  

  2) Just add sugar/water and swallow.

  3)  Once ingested the systems will organize and gain access to 
      your nervous system spinal fluid. 

  4)  Initial programming will create, almost overnight, 50 thousand
      meters of super conducting fiber a couple of molecules in diameter
      with almost 100 thousand terminal SQID detect/affect terminal pairs
      in all vital cerebral areas.

  5)  As the system becomes functional a 50 Million cpu, micro-spark 
      system will be generated around the nano factories.  All brain 
      activity may then be mapped, modeled, recorded and shared 
      with your friends.

  6)  It doesn't stop here! Share the new bio-tech with your friends!
      The software and bio-systems are fully redistributable using
      the GNU Copyleft and Patentleft licenses.

  Offer begins Oct. 2, 2150 ...

----

-- 
 +-  Bill England,  wengland@stephsf.COM -----------------------------------+
 |   * *      H -> He +24MeV                                                |
 |  * * * ... Oooo, we're having so much fun making itty bitty suns *       |
 |__ * * ___________________________________________________________________|
From: cash@cbnewsm.cb.att.com (john.i.mccash)
Newsgroups: rec.arts.sf.science
Subject: Re: Ringworlds & buckeytubes
Date: 10 Apr 92 19:21:00 GMT
Distribution: usa
Organization: AT&T

In article <2076@transfer.stratus.com> tarl@sw.stratus.com (Tarl Neustaedter) writes:
>In article <1992Apr9.202718.92@cbnewsm.cb.att.com>, cash@cbnewsm.cb.att.com (john.i.mccash) writes:
>> [buckytubes]
>> I'm not sure how to calculate the tensile
>> strength of such a fiber, but I'm sure it would be far in excess of any other
>> non-exotic (i.e. nuclear polymer, bound quarks, etc.) fiber possible. Any
>> chemists familiar with fullerenes care to comment?
>
>Uh, why would buckytubes be any stronger than diamond? The weak points are
>still the same single carbon-to-carbon covalent bonds. A buckytube would
>have *fewer* such bonds per cross-section area than diamond does.

Firstly, I plead ignorance. I don't know that much about the the covalent
bonds in a diamonds crystal lattice. I have no idea how many will cross
a given planar cross section of one square inch area, and that is the
information that would be required to calculate the tensile strength of a
fiber composed of flawless diamond. I lack the same information about the
fullerene fiber I describe above. It seemed, intuitively, to be, that the
fullerene fiber would be stronger, but that may well be incorrect. Once again,
any chemists out there care to comment? Secondly, diamond seems an awfully
brittle substance to use in such an application. A crack could prophogate
through it quite rapidly and cause the whole thing to break. This disadvantage
could possibly be overcome by using very thin fibers and spinning them into
a cable, though this would decrease the overall strength in comparison to a
monofilament of the same diameter. It might also be overcome by doping the
crystal with some substance which would retard crack growth. This might weaken
the fiber as well. Fullerenes, as I understand them (and I may not understand
them well at all) are both more flexible than pure diamond and self healing in
the event of damage, at least in the sense that the ruptured bonds will reform
with the nearest unpaired carbon rather than prophogating through the crystal.
									John
From: stevea@jab.tucson.az.us (Steve Albany)
Newsgroups: rec.arts.sf.science
Subject: Dyson Sphere Construction
Date: 11 Apr 92 21:50:43 GMT
Organization: Just Another Bbs. Tucson, AZ


        Seems to me that if a race were to construct a Dyson Sphere, they 
would have already mastered other technologies required to solve some of the 
nagging problems we've covered. Gravity, could be nullified by Anti-Grav 
Generators, etc..

        ================================================================
        |                    Capt. Steve E. Albany                     |
        |                 Cmdr. USS PATTON (NCC-8570)                  |
        |--------------------------------------------------------------|
        |                           | "My son, ask for thyself another |
        | SteveA@Coyote.Datalog.Com | kingdom, for that which I leave  |
        |  SteveA@Jab.Tucson.Az.Us  | is too small for thee.."         |
        |                           |    - King Phillip of Macedonia   |
        ================================================================
From: jhk6@cunixb.cc.columbia.edu (John H Kim)
Newsgroups: rec.arts.sf.science
Subject: Re: Virtual reality, the brain, and high-speed modems.
Date: 13 Apr 92 21:21:13 GMT
Article-I.D.: cunixf.1992Apr13.212113.334
Reply-To: jhk6@cunixb.cc.columbia.edu (John H Kim)
Organization: Columbia University

In article <12082@ns-mx.uiowa.edu> drenze@umaxc.weeg.uiowa.edu (Douglas J Renze) writes:
>In article <NICKH.92Apr7150003@VOILA.VENARI.CS.CMU.EDU> nickh@CS.CMU.EDU (Nick Haines) writes:
>> The brain is _not_ a bunch of electronic circuits, there are many 
>> different sorts of signals, and we don't know how much information is 
>> carried by each.
...
>I would go even farther than this.  How do we know that the routines are
>even the same from person to person?  Perhaps my eyes 'scan' vertically while
>yours scan horizontally...perhaps my image-processing routines are different
>than yours, ditto my auditory input routines, ditto my...well, you get the
>picture.  

There has been a fair amount of neurological work done testing the way the 
brain scans both visually and auditorially - I can give some references 
later if anyone asks. It appears that the routines (at least to some point) 
are not 'learned' skills, but rather inborn. 

It is true, however, that when different people look at the same scene, 
they will scan it a different way. Thus if you were given the direct 
optical nerve signal of someone else looking at a scene, you would just 
see a bunch of images jumping around in a crazy manner, because his eyes 
are not scanning it the same way yours would. 

People often do not recognize that vision is an active process - what 
objects in a scene we focus on and track is very much a product of who 
we are. 

What is inborn is how we percieve depth/distance, boundaries, motion, etc. 
and transform these into a three dimensional 'world-view' (picture of our 
surroundings in our mind). 

- John Kim
From: mahesh@numenor.next.nd.edu (Mahesh "BigMan" Subramanya)
Newsgroups: rec.arts.sf.science
Subject: Re: Dyson Sphere
Keywords: dyson
Date: 9 Apr 92 16:39:04 GMT
Article-I.D.: news.1992Apr9.163904.22732
Distribution: na
Organization: University of Notre Dame

In article <1992Apr9.154418.14501@acsu.buffalo.edu>  
v118qpx9@ubvmsb.cc.buffalo.edu (BYTEMAN, OF COURSE) writes:
> In article <1992Apr7.183343.18093@murdoch.acc.Virginia.EDU>,  
jes2x@fermi.clas.Virginia.EDU (John Sommerville) writes...
> >Could somebody tell me exactly what a Dyson sphere is, and in which  
books
> >one plays a large part?  I would be most grateful.

"Spinneret" by Timothy Zahn had a rather interesting use of a Dyson  
Sphere.  An Alien race with a Dyson Sphere around their yellow sun used it  
to caomuflage their existence by having it trap all the energy *except*  
that which would be radiated by a red sun.  The idea was that since the  
baddies new that the alien's sun was yellow, they would not look at this  
specific sun......

> 
>   
-------------------------------------------------------------------------- 
----
> | Sean Souva                      |                                             
|
> | V118QPX9@UBVMS.CC.BUFFALO.EDU   |            JESUS SAVES SINNERS!             
|
> |       (Smile! I'm a nice guy!)  |(and redeems them for valuable cash  
prizes) |
> |                                 |                                             
|
>   
-------------------------------------------------------------------------- 
----

--
*****************************************************************
Mahesh Subramanya               INTERNET: mahesh@darwin.cc.nd.edu
Senior Analyst                
Office of University Computing
University of Notre Dame        Voice:    (219) 239-5600  x6421
Notre Dame,  IN  46556