HDTenEightyP/NetNews huggingface dataset:
From: stevea@jab.tucson.az.us (Steve Albany)
Newsgroups: rec.arts.sf.science
Subject: Parallel Universes
Date: Wed, 15 Apr 92 23:39:13 PDT
Organization: Just Another Bbs. Tucson, AZ

        Sounds like a bunch of physists who have done far too much LSD!
 
 
 
        Seriously, I've always had a little more than doubt about PUs. But 
then, that ties into the belief that Time is more an abstract concept 
invented by man rather than a FORCE (which most in the QM field tend to 
believe it is).. But then, who am I? Not a Physist that's for sure.

        ================================================================
        |                    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: max@west.darkside.com (Max Pandaemonium)
Newsgroups: rec.arts.sf.science
Subject: Re: Dyson Sphere
Date: 10 Apr 92 19:21:15 GMT
Organization: The Dark Side of the Moon +1 408 245 SPAM

v118qpx9@ubvmsb.cc.buffalo.edu (BYTEMAN, OF COURSE) writes:

> Larry Niven has a collection of short stories call _A Hole in Space_.
> I believe he has a short speculation piece on a variety of worlds that could 
> built for exploration, living space, etc.  One of them was a Dyson sphere; he
> even went so far as to describe one spinning to produce the necessary gravity
> Very fascinating "article."

The article is called "Larger Than Worlds" and is quite interesting.  Ir 
ranges from ship-sized living places (like Heinlein's _Universe_ ship) 
and goes up to bubble-worlds, tubes circling stars, Ringworlds, Dyson 
spheres, Alderson discs, and even galaxy-sized Dyson spheres.

Quite interesting . . .


----------
Max Pandaemonium   Omnia quia sunt, lumina sunt.  Coming soon:  UNIVERSE _ | _
USmail:  1070 Oakmont Dr. #1 San Jose CA 95117  ICBM:  37 20 N  121 53 W _>|<_
UUCP:  ..!apple!uuwest!max   Usenet:  max@west.darkside.com   464E4F5244   |
From: lfd@cbnewsm.cb.att.com (Lee Derbenwick)
Newsgroups: rec.arts.sf.science
Subject: Re: Kevlar Balloon Space Station mk II
Summary: If foil, paint it!
Date: 16 Apr 92 22:09:56 GMT
Organization: AT&T

In article <1992Apr16.005054.39402@kuhub.cc.ukans.edu>, 2frssprout@kuhub.cc.ukans.edu writes:
> To summarize the issue:  Why not use Kevlar balloons as space station hulls?
> 
> Problems:  Radiation (hard, soft, and electromagnetic), affecting both the
>            Kevlar (James William Stepanek claims polymers tend to break down
>            under intense UV) and the people (EM and hard stuff).  
> 
> Response:  Fix UV and EM problems by an outside layer of aluminum foil?

If you don't want _hot_ kevlar, you'd better add a coat of white
paint, too.  (Actually, even moderate-colored paint might help.)
There's a lot of UV up there, and metals that are nice and
reflective in the visible and infrared ranges are fairly good
absorbers of UV.  So they absorb UV, but they don't radiate IR
well.  Thus, they get, uh, warm...

(I know, the Echo satellite was shiny.  But it had no contents;
it was _just_ a balloon, so unless it reached the breakdown
temperature for mylar, it didn't matter.)

 -- Speaking strictly for myself,
 --   Lee Derbenwick, AT&T Bell Laboratories, Warren, NJ
 --   lfd@cbnewsm.ATT.COM  or  <wherever>!att!cbnewsm!lfd
From: s861022@minyos.xx.rmit.oz.au (Harry the Dirty Dog)
Newsgroups: rec.arts.sf.science
Subject: Re: Dyson Sphere & Ringworlds
Date: 9 Apr 92 01:12:09 GMT
Organization: Green Bomb Design Team & Assoc.

randy@rss.dl.nec.com (Randy Bullard) writes:

>In article <3427@balrog.ctron.com>, smith@ctron.com (Larry Smith) writes:
>|> In article <1992Apr7.183343.18093@murdoch.acc.Virginia.EDU>, jes2x@fermi.clas.Virginia.EDU (John Sommerville) writes:
>|> a surface area around 1e9 times the Earth's.  No novels I am aware of use
>|> the idea directly, but Niven's Ringworld stories ("Ringworld" and "The
>|> Ringworld Engineers") use the idea of a rotating ring surrounding the sun,

>One of Robert Silverberg's earlier works "Across a Billion Years" 

Hasn't anyone heard of Orbitsville and Orbitsville Departure by Bob Shaw.
Now that most definately features the idea of a Dyson Sphere.
-- 
Harry the Dirty Dog           "That's the problem with plutonium, it's
                               pretty limited in its applications. It's not
s861022@minyos.xx.rmit.oz.au   user friendly, but as a vehicle for regaining
                               self respect, its got a lot going for it"
                                  - Darius Jedburgh
Organization: Senior, Math/Computer Science, Carnegie Mellon, Pittsburgh, PA
Newsgroups: rec.arts.sf.science
Date: Thu,  9 Apr 1992 11:46:19 -0400 
From: "Andrew C. Plotkin" <ap1i+@andrew.cmu.edu>
Subject: Re: Virtual reality, the brain, and high-speed modems.
	<1992Apr9.011807.20047@cs.rose-hulman.edu>

Excerpts from netnews.rec.arts.sf.science: 9-Apr-92 Re: Virtual reality,
the br.. Greg Kemp@NeXTwork.Rose- (1392)

> Earlier today, I read a book outside.   
> How much information would be required to simulate the breeze on my face,  
> the cold ground beneath, the rough tree bark to my back, the scent of the  
> flowers just coming into bloom, the song of the birds, and the look and  
> feel of the book in my hands? 

Well, that's just it. Nobody knows.

It seems (to me :-) that the brain does a *lot* of data-compression in
storing memories, and it does it at a fairly high level. You remember a
breeze on your face, but not the exact pattern of pressure and
direction. If someone simulated the scene, and reconstructed a
breeze-sensation from just the words "a breeze on your face" and a few
bytes of temperature data, could you tell the difference? So the amount
of data needed to *store* a scene in your head might be quite small.
(Smallish. Not immense, anyway.) 

So if I were designing a sim-stim technology, I would have it work at
that level, instead of the "low level" of rods and cones, or individual
skin nerve endings. Shove the condensed data directly into the mind. The
memories you wind up with are of exactly the same quality as memories of
real scenes, so how could you tell the difference? 

(One might complain that the *memories* are the same, but the immediate
experience of the scene would be different. To which I reply, what the
hell do you mean by that? A difference that by definition you can't
remember?)

This argument is heavily influenced by a book I read recently and mostly
agree with, entitled _Consciousness Explained_ (ego? What ego? :-) by
Daniel Dennett. I don't know how well-regarded _CE_ is among
Professional Philosophers, but it gave a number of examples which seem
to support what I'm saying.

The obvious problem with this approach (well, nothing's obvious with
such up-in-the-air theorizing, but anyway) is that the "encoding" is
likely to be very individual to each brain; it's based on chunking data
into meanings and ideas, and I doubt there's any nice way to map
meanings to nerve cells. So you might have to spend a few days
baselining your cyberdeck, either by watching various images as the
machine reads your brain, or by letting it zap your brain at random
until it works out what's what. Or maybe it would take a few years. I
dunno.

--Z

"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the borogoves..."
Newsgroups: rec.arts.sf.science
From: jes2x@fermi.clas.Virginia.EDU (John Sommerville)
Subject: Dyson Sphere
Organization: University of Virginia
Date: Tue, 7 Apr 1992 18:33:43 GMT

Could somebody tell me exactly what a Dyson sphere is, and in which books
one plays a large part?  I would be most grateful.

--
John Sommerville (jes2x@Virginia.Edu)    <<Ren and Stimpy in '92!>>
Rose tint my world, keep me safe from my trouble and pain- RHPS
From: stevea@jab.tucson.az.us (Steve Albany)
Newsgroups: rec.arts.sf.science
Subject: Alternate Universes
Date: Wed, 15 Apr 92 23:42:54 PDT
Organization: Just Another Bbs. Tucson, AZ

        Now this one is a little more probable in my book. I mean seriously, 
it seems pretty damn likely. Take the BIG BANG or STEADY STATE Models of the 
Universe. My big question, especially concerning the BB Model, is hey, ok, 
the Universe was created from a relatively small ball of cosmic stuff, and 
BLAM-O, Insta-Universe. What exsists beyond the confines of this universe. 
What kind of "space" is being filled up by our Universe.. Etc..
        Anyway, I find this subject just as intriguing as the PU thread, 
although, as I said, a bit more probable..

        ================================================================
        |                    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: mss2@quads.uchicago.edu (Michael S. Schiffer)
Newsgroups: rec.arts.sf.science
Subject: Re: Psychohistory
Date: 15 Apr 92 21:30:35 GMT
Reply-To: mss2@midway.uchicago.edu
Organization: University of Chicago Computing Organizations

In article <1992Apr15.205315.5794@spss.com> markrose@spss.com (Mark Rosenfelder) writes:

>Asimov's essays.)  If the world is ripe for a particular scientific
>discovery, there's no stopping it.

Maybe, but there are historical counterexamples.  In the Byzantine Empire,
Greek Fire was developed by a single individual, and the secret of its
making was kept for centuries.  (In fact, it's still "kept" in the sense
that we don't know exactly how to make it, though we have a decent idea
what chemicals would produce its effects.)

>Perhaps the Galactic Empire, or the Second Foundation, has such fascistic
>control of every planet in the galaxy that nothing like psychohistory can
>develop outside Seldon's project?  Well, one, I don't believe it, two,
>such a totalitarian regime is antithetical to scientific inquiry anyway,
>and three, such a regime isn't worth preserving from the dark ages.

Remember, the Galactic Empire _did_ suppress psychohistory-- or so it
thought.  It exiled Seldon's project to the end of the galaxy.
Besides which, one of the signs of decadence was a slowdown in
scientific research and innovation, such that within a half century
after Seldon some areas of the galaxy were _losing_ technologies
they'd had for centuries.  If developing psychohistory required
genius on the level of a Gauss or a Newton, plus access to a library
as good as the one at Trantor for necessary research, plus interest
in pure research in a culture which didn't value it, it seems easily
possible that Seldon was unique.  Maybe someone would have developed
psychohistory fifty or a hundred years later-- except that by then
the conditions would make it even less possible.

Consider the level of mathematical science in the classical world at
the time of Archimedes, and compare it to mathematics in the same
region a thousand years later.  Where Archimedes was arguably within a
hair's breadth of discovering calculus (but was hampered by his
numerals, among other things) as it happened it wasn't near
"calculus-inventing time" again for more than a millennium and a half
afterward-- at which point it was discovered by two people independently.


Mike
-- 
Michael S. Schiffer, LHN, FCS	"Never let your sense of morality prevent
mss2@midway.uchicago.edu	 you from doing what's right!"
mike.schiffer@um.cc.umich.edu	 --Mayor Salvor Hardin of Terminus
mss2@usite-next.uchicago.edu     Isaac Asimov, _Foundation_
From: tarl@sw.stratus.com (Tarl Neustaedter)
Newsgroups: rec.arts.sf.science
Subject: Re: Ringworlds & buckeytubes
Date: 10 Apr 92 01:09:04 GMT
Distribution: usa
Organization: Stratus Computer, Inc.

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.
-- 
         Tarl Neustaedter	tarl@sw.stratus.com
         Marlboro, Mass.	Stratus Computer
Disclaimer: My employer is not responsible for my opinions.
Newsgroups: rec.arts.sf.science
From: ingles@cclittle.engin.umich.edu (Ray Ingles)
Subject: Re: Chaos vs psychohistory
Date: Wed, 08 Apr 92 16:25:55 EDT
Organization: University of Michigan Engineering, Ann Arbor


In article <72555@netnews.upenn.edu>, weemba@libra.wistar.upenn.edu (Matthew P Wiener) writes:
> In article <a!g+MsA@engin.umich.edu>, ingles@finch (Ray Ingles) writes:
> > But the way I read the Foundation series was that psychohistory was
> >invalid for small systems ("small" relative to the population of a
> >galaxy) and worked peachy for sufficiently large systems. (Of course, as
> >you point out, there *was* a regulating mechanism.) No mention was made
> >of "problematic" areas, (corresponding to your "islands of non-chaos"
> >above) as long as the problems were of sufficient size. This is no slight
> >on Asimov; "chaos" as such wouldn't really be recognized for decades.
> 
> Just like Asimov revealed in F'S EDGE that Trantor was of course next
> door to the black hole at the center of the galaxy, he revealed in
> PRELUDE2F that the predictive power of psychohistory should come from
> these islands.

 Oh. Well, then, we're talking about two different things, I'm
talking about Psychohistory V1.0, and you're using V2.0. Oh,
well. :->

> > Anyway. While it's true that we now know of some ways of controlling
> >chaotic processes, from my understanding it requires that we have
> >near-total control of (at least) one of the variables involved.
> 
> This is just the first round of our understanding.  Who knows what other
> mechanisms could be possible?

 Perhaps by imperfect control of one or more variables we could
control chaotic systems; indeed, since slight differences lead to
large-scale changes, this should be possible. But the smaller the
difference the longer it takes to have an effect... so it'll
probably be along time before we have, say, real-time control of
the weather.

> >								 In the
> >system I read about (control of vibrations in a magnetoelastic ribbon),
> >the experimenters could measure to reasonable accuracy all relevant
> >variables and control the strength of the applied field. Whether this
> >would ever be possible in a social system seems doubtful to me.
> > Weather control, for example, seems to still be a dream. [...]
> 
> Well yes.  For one thing, we don't really know the relevant equations,
> just bits and pieces.  I have no idea if humanity en masse is more or
> less comprehensible than weather, so while I don't particularly believe
> in psychohistory, I think anyone who claims it's provably impossible is
> probably speaking nonsense.  Certainly the fellow I responded to was.
> (And no, I did not see his paper either.)
>
> -Matthew P Wiener (weemba@libra.wistar.upenn.edu)

 Well, I agree with that. I don't think you could *prove* that some
kind of psychohistory is impossible, but it does seem unlikely...

Sincerely,

Ray Ingles                  || The above opinions are probably
                            || not those of the University of
ingles@caen.engin.umich.edu || Michigan. Yet.
From: John_Jenkins@taligent.com (John H. Jenkins)
Newsgroups: rec.arts.sf.science
Subject: Re: Psychohistory
Date: 10 Apr 92 23:57:53 GMT
Organization: Taligent, Inc.

In article <1992Apr09.160916.14693@onetouch.COM>, csmith@onetouch.COM (Craig Smith) writes:

[Remarks on the basis for psychohistory, etc. deleted]

> 
> 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?
> 
> 

This is the "great man" school of historiography, which not everyone accepts.
For example, you could argue that Hitler "caused" WW2.  Had it not been for
that Austian painter, millions of people would have lived longer, happier
lives. 

On the other hand, you could argue that Hitler did not cause anything.  Had
he never been born (or had you gone back in a time machine and killed him as
a boy), the "forces of history" would have swept somebody else into his
place.  WW2 would still have been fought; it might have been a different
war, with different goals and a different conclusion, but the war itself
was unavoidable.

Asimov subscribed to this latter philosophy.  Moreover, he extrapolated
that given a large enough population base, the impersonal "forces of
history" take over.  If Adolf Hitler hadn't been taken over Germany and
launched Nazism, somebody very like him would have started an almost
identical movement.  The larger the sample, the better the statistical
method works.  "Great men" don't count for much.  

If only one person in a hundred billion are like Hitler, in other words,
then by the time your population is measured in trillions or quadrillions,
you've got a darn goot chance of getting at least one.  

Spoilers follow--



Besides, Asimov stacked the deck.  The Second Foundation and R. Daneel
were running around to make sure that things stayed on course.  (Although
I can't remember if Daneel ever said that he actively intervened in 
Foundation history to make sure the Seldon Plan would work.)

John H. Jenkins
John_Jenkins@taligent.com
From: nickh@CS.CMU.EDU (Nick Haines)
Newsgroups: rec.arts.sf.science
Subject: Strength of skrith (sp?)
Date: 8 Apr 92 20:21:10 GMT
Article-I.D.: VOILA.NICKH.92Apr8152110
	<3427@balrog.ctron.com>
Organization: School of Computer Science, Carnegie Mellon University
Originator: nickh@VOILA.VENARI.CS.CMU.EDU

In article <3427@balrog.ctron.com> smith@ctron.com (Larry Smith) writes:

   Question: Niven says that a Ringworld needs to spin at 770 miles/sec to
   maintain 1g at 1au.  How strong a material is needed to support this?
   Can diamond fiber do the job, or is it beyond any theoretical material?

The speed Niven gives is correct, but is irrelevant to the question of
strength as it happens. We don't know how strong the material has to
be, because we don't know how dense it is (or, rather, how massive the
Ringworld is).  Let's work it out with some guesses at the critical
figures.

Right, basically, the tension in the Ringworld is equal to 1/(4\pi)
(about 1/12) the weight of the whole thing (he says, after 1 minute
sketching a diagram). This is equivalent to being able to support
0.5AUs (ie 75 million kilometres) of itself under 1g. I seem to recall
that the RW has mass something similar to Jupiter, which is, erm,
about 2e28kg (?) so the tension is about 2e27 N and the area is about
2e21 m^2 (?), so the surface density is 1e7 kg/m^2. The tension seems
like a lot. It's a million miles wide, so that's 1e18 N/m. Suppose
it's made out of diamond, which has a density of, erm, call it
3e3kg/m^3 (?).  Then it's 3e3 metres thick (wow, 3 kilometres of
diamond...), and the tensile strength required is 3e14 Pa, or 4e10 psi
for those of you still working in primitive units :-). I seem to
recall ordinary materials having strengths around 1e7 Pa, but can't be
sure.

Anyone want to check my math, or have figures for tensile strengths of
exotic materials?

Of course, a practical Ringworld has to be much stronger, to withstand
impacts :-)

Nick Haines nickh@cs.cmu.edu
From: nickh@CS.CMU.EDU (Nick Haines)
Newsgroups: rec.arts.sf.science
Subject: Re: Alternate Universes
Date: 16 Apr 92 20:55:44 GMT
Organization: School of Computer Science, Carnegie Mellon University
Originator: nickh@VOILA.VENARI.CS.CMU.EDU

In article <827aJB4w164w@jab.tucson.az.us> stevea@jab.tucson.az.us (Steve Albany) writes:
                                 My big question, especially
   concerning the [big bang] model is hey, ok, the Universe was created from
   a relatively small ball of cosmic stuff, and BLAM-O, Insta-Universe.
   What exists beyond the confines of this universe.
   What kind of "space" is being filled up by our Universe.. Etc..

Well, the Universe that is created (/expanded/inflated) in the
`BLAM-O' event does not just include the matter, but also all the
space in between. Think of drawing dots on a balloon and then
inflating it. The dots are the galaxies, the rubber is the space. What
exists beyond the `confines' of the balloon? (i.e. what was in the
`rubber' before the dots `got there'). What kind of rubber is being
filled up by our balloon? This kind of question doesn't really have a
sensible answer.

By the way, steady-state is old hat.

Oh, and something that really bugs me is this assumption by people
that our universe has some finite total size. This is _not_ implicit
in the big bang model. The big bang happens _everywhere_ when it
happens---there _is_ no space `outside cosmic egg'. So why should it
be finite? A lot of cosmologists don't believe that it's so. Even if
our universe has enough curvature (i.e. density) to be closed, it
_need_not_ be closed (it could be a more complicated manifold).

Nick Haines nickh@cs.cmu.edu
From: kempga@NeXTwork.Rose-Hulman.Edu (Greg Kemp)
Subject: Re: Virtual reality, the brain, and high-speed modems.
Reply-To: kempga@NeXTwork.Rose-Hulman.Edu
Organization: Rose-Hulman Institute of Technology
Date: Tue, 7 Apr 1992 18:20:53 GMT

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?

More information than you think.  Human vision consists of ~10^8 pixels  
with 16 bits of color information per pixel (humans can distinguish ~14  
million colors).  Images are processed at about 24 per second.  This comes  
to about 20 gigabytes per second per person (very rough ballpark figure).   
That's a whole lotta bits.  Today's best systems are still 1000x too slow  
for this.  For now, the only way to move that much information is to look  
at something and let your eyes do the seeing.

> Mike Gebis   mjg51721@uxa.cso.uiuc.edu   OR   m-gebis@uiuc.edu
--
Greg Kemp
inmate, Rose-Hulman Institute of Technology
Internet: kempga@rosevc.rose-hulman.edu