HDTenEightyP/NetNews huggingface dataset:
From: max@west.darkside.com (Max Pandaemonium)
Newsgroups: rec.arts.sf.science
Subject: Re: What if the Sun dimmed?
Date: 12 Apr 92 07:40:09 GMT
Organization: The Dark Side of the Moon +1 408 245 SPAM

moonman@camelot.bradley.edu (Craig Levin) writes:

> 	I have been taking an astronomy class, and we were discussing
> the issue of the solar neutrino problem-that only a third of the
> expected yield of neutrinos was being observed-and I had a brainflash:
> the core of the sun has cooled, and as the effects of this core
> cooling percolate through the rest of the sun, the sun will radiate
> less energy and cool. Have there ever been any stories about the
> effects of a suddenly cooler sun, and, if not, what might these
> effects be?

I can think of two off the top of my head:  Niven, Barnes, and Flynn's 
_Fallen Angels_ and Niven and Barnes' _The Barsoom Project_ (if you can't 
tell, I'm a Niven fan).

They both stem from the idea that, _yes,_ the Sun isn't producing as much 
neutrinos as it should; that's because it's actually cooler.  In _The 
Barsoom Project_ (actually, a Game played within the context of the major 
plot), the Sun has dimmed a _great_ deal, and the Earth is freezing 
solid.

The idea behind _Fallen Angels_ is that the only reason Earth hadn't 
entered its next Ice Age centuries ago was because of man-made pollution. 
Environmentalists take control of the United States government, set up a 
totalitarian regime to reduce the harm to the environment, and cut down 
on greenhouse gas emissions excessively (similar things happen in other 
major industrial countries as well).  As a result, Earth is kicked into 
an Ice Age.  The whole world becomes a giant war from North vs. South, as 
the glaciers march south to engulf northern countries.  All of Canada and 
most of the northern United States have been evacuated at the time of the 
story.

Quite a disquieting thought, really . . .

----------
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 _>|<_
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Newsgroups: rec.arts.sf.science
From: sane@cs.uiuc.edu (Aamod Sane)
Subject: Re: Psychohistory
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
Date: Mon, 13 Apr 1992 23:02:14 GMT

markrose@spss.com (Mark Rosenfelder) writes:

>Comments:

>   Interviewer: Welcome to 'State your claim'!  First, we have with us
>      psychohistorian Hari Seldon!

>   Hari Seldon: My theory is that when you get enough people together
>     history is determinate.  I say the Galactic Empire is going to
>     fall apart for 30,000 years.  However, with careful management
>     this can be reduced to 1000 years.

Correction:
   Hari Seldon: My theory is that when you get enough people 
     *who do not know psychohistory* together
     history is determinate.  I say the Galactic Empire is going to
     fall apart for 30,000 years.  However, with careful management
     this can be reduced to 1000 years.
	
Therefore, the following does not follow.

>   Interviewer: But that wouldn't happen if you had never existed, 
>     would it?  Isn't that a whacking big difference for one individual
>     to make?

>   Hari Seldon: Well, this is where my theory falls to the ground.


QOTD:

Dead in all but name, wandering lost somewhere amongst the steep green
 hills sketched on the his EEG screen. His body's the grave of his
 mind, rooted there, translucent stalks rise from vein and nostril
 into grass flowers. containing glucose to lure bees. If touched, they
 chime, brief and melancholy.
	- Loose Ends ( Reprisals ), Swamp Thing, Alan Moore.
-- 
sane@cs.uiuc.edu
         ==         / \  
-----    ==    *    \_/     -|||- 
         ==     
Newsgroups: rec.arts.sf.science
From: garyg@netcom.com (Gary Greene)
Subject: Re: Cherryh's technology (was: SF about doing science ?)
Date: Thu, 16 Apr 92 10:00:29 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
Keywords: Don't read _Twistor_

s5223927@titan.ucc.umass.edu (Daniel Lescohier) writes:

>In article <1992Apr14.041927.16381@ccu1.aukuni.ac.nz> ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig) writes:
>>
>>One other thing which peeves me are the speed and acceleration.
>>Accelerating at 10 g's will not get you up to light speed in a matter
>>of minutes.

>	True.  It would take about 35 days to get to light speed at 10g
>acceleration (3*10^8 m/s / 100 m/s^2 = 3*10^6 s = approx. 35 days.)
>That's extremely fast compared to today's standards, however.
 
You folks may be right, but does this calculation account for time
dilation for the crew?  I'll need to look at her accounts again to see
how long it appears to the station's approach control, and minutes is not
the duration I remember her listing for acceleration to c.  The crew of 
the starship would clearly experience a much shorter subjective approach 
time than the 35 days you calculate.  Seems to me the normal acceleration
she lists takes more than a number of days for the crew to acheive near
light speed, not minutes.  At 75% c time dilation is not much, but as it
approaches 95% the dilation builds rapidly if I recall corectly.

Respects,

Gary Greene						garyg@netcom.com
San Jose, California


>-- 
> Daniel Lescohier        | InterNet: s5223927@titan.ucs.umass.edu (until May)
> Univ. of Massachusetts  |---------------------------------------------------
> Amherst, MA (until May) | FidoNet:  1:101/138 (permament address; after May)
>  [quote deleted]        |        (Daniel.Lescohier@f138.n101.z1.fidonet.org)
From: drenze@umaxc.weeg.uiowa.edu (Douglas J Renze)
Newsgroups: rec.arts.sf.science
Subject: Re: Virtual reality, the brain, and high-speed modems.
Date: 9 Apr 92 17:55:25 GMT
Organization: U of Iowa, Iowa City, IA

In article <NICKH.92Apr7150003@VOILA.VENARI.CS.CMU.EDU> nickh@CS.CMU.EDU (Nick Haines) writes:
>2. talking of the `I/O bandwidth' of the brain (for instance) is
>   mixing ones metaphors: the brain is _not_ a bunch of electrical (or
>   electronic) circuits, there are many different sorts of signals,
>   and we don't know how much information is carried by each (loosely,
>   all the systems are not just analogue circuits, but analogue circuits
>   that are parameterized by other sorts of signals (eg.
>   blood-chemicals).
>
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.  After all, each individual has to learn how to process information
on his or her own...I should think that a necessary consequence of this is
that each individual would, therefore, develop slightly different information-
processing algorithms.  After all, how else could you explain the fact that
some people can look at a series of unconnected clues and solve an investi-
gation at a glance, while to others, they remain a series of unconnected clues?

--
Douglas J Renze
drenze@umaxc.weeg.uiowa.edu
+1 319 337 4664
From: stig@Lise.Unit.NO (Stig Hemmer)
Newsgroups: rec.arts.sf.science
Subject: Re: Parallel Universes
Date: 15 Apr 92 21:56:37 GMT
Organization: Anarchy

In article <1992Apr15.040437.16828@latcs1.lat.oz.au>, burns@latcs1.lat.oz.au (Jonathan Burns) writes:
[...]
> There _is_ a theory of splitting universes, generally known as Everett's
> Many-Worlds Interpretation. It has been fairly deeply reasoned through.
> It stands up as a _consistent_ interpretation of quantum measurement.

This question isn't just directed to Jonathan but to anyone who think
they know the answer.

If I have understood things correctly the MWI people state that
nothing really significant happens when you do a measurement.

If this is so, how does they explain the recent experiments where
measurement one place are affected by whether or not a measurement is
made elsewhere?

(What happens is that a wave-like multi-hump interference pattern
changes into a particle-like single-hump (non)interference pattern)

Stig 'Tortoise' Hemmer   aka   stig@lise.unit.no
.no means Norway, a minor kingdom in northern Europe.
Europe is a moon of Jupiters.
This is NOT a .signature virus. Do NOT copy it into your .signature
From: neufeld@helios.physics.utoronto.ca (Christopher Neufeld)
Newsgroups: rec.arts.sf.science
Subject: Re: Dyson Sphere
Date: 12 Apr 92 00:40:36 GMT
Article-I.D.: helios.1992Apr12.004036.3665
Organization: University of Toronto Physics/Astronomy/CITA

In article <1992Apr11.042042.12230@ux1.cso.uiuc.edu> tbmg9061@uxa.cso.uiuc.edu (Thomas B MacIukenas) writes:
>
>You can add this to the lengthy list of problems with Dyson spheres:
>
>Some kind of system is needed to hold the thing up.  Spinning doesn't
>work for spheres, since the top and bottom will cave in.   And you
>can't use a system of free flyers, all of which are in stable orbits,
>because you could never work out a system of interlocking orbits which
>would guarantee no collisions (and that's ignoring gravitational effects
>between the flyers!).
>
   Of course you could work out the orbits! I can only guess you're
assuming that all the orbits are exactly the same distance from the Sun,
and are all exactly circular. Why limit yourself? The idea is to capture
the full power output of the Sun. This means a line drawn from the
surface of the Sun outward in any direction should hit a free flyer. They
could be in a region thousands, millions, or tens of millions of
kilometres thick quite easily. Of course, that implies that a given free
flyer probably won't be in continual sunlight, but that wasn't the idea
of building the Dyson sphere anyway.
   As for mutual gravitational interactions, they are small. Remember
that as designed the Dyson sphere tries to be a uniform spherical shell.
This geometry is a particularly easy one, and integrated over several
orbits its effects should balance to zero (the design of a Dyson sphere
implies the absence of mass multipole moments above l=0).

>You need some kind of thrust system capable of
>holding the sphere up against the sun's gravitational pull.  That won't
>be cheap, and you'll basically be sending a continuous shower of matter
>into the sun (radiation pressure systems won't work, so you need some
>kind of reaction mass system).
>
   If you do want to build a continuous solid, then unless it is
extremely rigid you will need some effective repulsion from the Sun. You
can do it with radiation pressure. Just make sure that the power density
inside the sphere is significantly greater than that outside the sphere.
In other words, a given photon can provide a lot of outward momentum if
it bounces from one part of the sphere to another, while an outgoing
photon can only provide an inward push once. Of course, this has the
effect of heating the Sun a bit.

>___-Tom_Maciukenas_(tbmg9061@uxa.cso.uiuc.edu)_________________________________


-- 
 Christopher Neufeld....Just a graduate student  | alien: n. a being who
 neufeld@helios.physics.utoronto.ca    Ad astra  | travels great distances
 cneufeld@terranet.cts.com                       | to molest our cattle
 "Don't edit reality for the sake of simplicity" | and trample our grain
Newsgroups: rec.arts.sf.science
Subject: Re: Strength of skrith (sp?)
From: ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig)
Date: Mon, 13 Apr 1992 06:45:43 GMT
Organization: University of Auckland, New Zealand.

nickh@CS.CMU.EDU (Nick Haines) writes:

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

Let's treat this as an example of technical mechanics :-)

We can model the Ringworld as a consisting of three parts: the scrith in
the floor, the dirt above and the air to top it all.

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

a is known (about earth's surface acceleration), R is about one AU.  What
about M?

Defining B as the breadth of it all, rho_s the density of the scrith,
rho_d the density of the dirt above, d_s the thickness of the scrith,
d_d the thickness of the dirt and p_a the atmospheric pressure, we get:

M = B *(rho_s * d_s + rho_d * d_d + p_a / a)

The first two terms should be obvious, the third one should become clear
if you cut free a column of air above the ground.

So, F = ((rho_s * d_s + rho_d * d_d) * a + p_a) * B * R

Tension, which we have been looking for all the time :-) is defined by
sigma = F / A, in this case the scrith's.

A = B * d_s, so

sigma = 1/ (B * d_s) * (( rho_s * d_s + rho_d * d_d) * a + p_a) * B * R

or, striking out B,

sigma = 1/ d_s * (( rho_s * d_s + rho_d * d_d) * a + p_a) * R

(Anyone familiar with technical mechanics will see, BTW, that this problem
is very much like a tube under internal pressure.)

Now it's time to plug in some values.

Let's say d_s and d_d are both 30 m, rho_s = 1E4 kg/m^3 (a bit more than
steel), rho_s = 3E3 kg/m^3 (average rock), p_a = 1E5 N/m^2, which is
about what Earth has at sea level, a = 10 m/s^2, and R = 1.5E11 m (one AU).
What we get is a tension of 2E16 N/m^2.

Steel has up to 2E9 N/m^2 (or 2000 N/mm^2, if that makes you feel more at
home), so it's a factor of ten million between the two, but that steel will
be brittle; 2E8 N/m^2 is a more comfortable value.

With more exotic materials, you'll get factors of maybe ten or a hundred
over the best steel, but that's still a long way off.  None of these
materials could be shaped into the Fist of God, anyway, because they
usually cannot be subjected to much plastic deformation.

If you play around with the above formula a bit, plus the one for centri-
fugal acceleration, which is a = v^2 / r, will also get the maximum size
for the diameter of a space station using centrifugal force to simulate
gravity; I'm afraid Cherryh may have to scale hers down a bit, or at
least give them a more cylindrical form :-)
-- 
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
Subject: Re: Dyson Sphere
From: chisnall@cosc.canterbury.ac.nz (The Technicolour Throw-up)
Date: 13 Apr 92 23:42:52 +1200
Reply-To: chisnall@cosc.canterbury.ac.nz
Distribution: world
Organization: Computer Science,University of Canterbury,New Zealand

From article <1992Apr08.232317.5570@onetouch.COM>, by csmith@onetouch.COM (Craig Smith):
> A number of problems with the idea:
>    1) It requires artificial gravity (spinning the sphere doesn't work)

Whats wrong with velcro?  Why use hi-tech solutions when lo-tech ones
suffice?

--
Just my two rubber ningis worth.
Name: Michael Chisnall          email: chisnall@cosc.canterbury.ac.nz
I'm not a .signature virus and nor do I play one on tv.
From: markrose@spss.com (Mark Rosenfelder)
Newsgroups: rec.arts.sf.science
Subject: Re: Psychohistory
Date: 16 Apr 92 16:33:32 GMT
Organization: SPSS Inc.

In article <1992Apr15.213035.21790@midway.uchicago.edu> mss2@midway.uchicago.edu writes:
>Remember, the Galactic Empire _did_ suppress psychohistory-- or so it
>thought.  It exiled Seldon's project to the end of the galaxy.

Yes, that's what happened in the book.  I'm talking about whether this
is plausible.

>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, 

Implausibilities all.  Our planet, of a mere billion people, produces
geniuses of this caliber several times per century.  And if there's only
one really good research library in the Galactic Empire, and/or no way
to access it off-planet, it *deserves* to die.  I also have problems with 
a *galactic* culture declining in a matter of centuries. 

>it seems easily
>possible that Seldon was unique.  

So the history of the galaxy depends on the existence of one
person, and psychohistory is in grave trouble.  QED.

>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.  [...]

I think it's significant that you are driven to the ancient world to find
analogies to Asimov's Galactic Empire.  That's part of the problem.
The Galactic Empire and its decline is more or less a scale-up of the
Roman Empire.  (I could veer off into a comparison of the Foundation(s)
and the Church, but I think I won't.)  I get much more of a sense of an
enormously complicated galactic society from Poul Anderson, or Douglas Adams. 

(someday I must read some authors beginning with B :-)
Newsgroups: rec.arts.sf.science
From: sane@cs.uiuc.edu (Aamod Sane)
Subject: Re: Psychohistory
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
Date: Tue, 14 Apr 1992 23:36:59 GMT

markrose@spss.com (Mark Rosenfelder) writes:

>For an interesting argument that the social sciences will never be able
>to be as predictive or reductive as the physical sciences, see John
>Searle's _Minds, Brains, and Science_, chapter 5.

I have not read this book, but I would say that the "Butterfly Effect"
is a good argument against predictability. One of my
favorite butterfly effect examples is Stilgar's reminiscences early
in Children of Dune - something like - "He thought of the fragile chain
of events that led to the children being in the cave. If he were
to kill them now..."

>(Myself, I think psychohistory is impossible, but makes for some very
>entertaining stories, at least till R. Daneel turns up.)

I agree. The R. Daneel connection ruined Foundation for me.

Aamod Sane

QOTD:

"Power outage at a department store yesterday, Twenty people
 were trapped on the escalators." -- Steven Wright
-- 
sane@cs.uiuc.edu
         ==         / \  
-----    ==    *    \_/     -|||- 
         ==     
Newsgroups: rec.arts.sf.science
From: kasprj@isaac.its.rpi.edu (Jim Kasprzak)
Subject: Re: Dyson Sphere
Reply-To: kasprj@rpi.edu
Organization: The Big Wedge
Date: Mon, 13 Apr 1992 21:32:41 GMT

In article <1992Apr13.234253.4664@csc.canterbury.ac.nz>, chisnall@cosc.canterbury.ac.nz (The Technicolour Throw-up) writes:
|> From article <1992Apr08.232317.5570@onetouch.COM>, by csmith@onetouch.COM (Craig Smith):
|> > A number of problems with the idea:
|> >    1) It requires artificial gravity (spinning the sphere doesn't work)
|> 
|> Whats wrong with velcro?  Why use hi-tech solutions when lo-tech ones
|> suffice?
 
 It'd take one _hell_ of a lot of velcro to hold the atmosphere in place.
------------------------------------------------------------------
     __  Live from Capitaland, heart of the Empire State...
 ___/  | Jim Kasprzak, computer operator @ RPI, Troy, NY, USA
/____ *| Why can't people stop taking things so seriously? 
     \_| "All I want is to have my peace of mind" - Boston   
      ====  e-mail: kasprj@rpi.edu or kasprzak@mts.rpi.edu
From: nickh@CS.CMU.EDU (Nick Haines)
Newsgroups: rec.arts.sf.science
Subject: Re: Virtual reality, the brain, and high-speed modems.
Date: 7 Apr 92 20:09:33 GMT
	<1992Apr7.182053.27694@cs.rose-hulman.edu>
Organization: School of Computer Science, Carnegie Mellon University
Originator: nickh@VOILA.VENARI.CS.CMU.EDU

In article <1992Apr7.182053.27694@cs.rose-hulman.edu> kempga@NeXTwork.Rose-Hulman.Edu (Greg Kemp) writes:

   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).   

Ahem.

1. Human vision does _not_ consist of as many as 10^8 pixels. Most of
one's visual field is kept hanging around by wetware---the actual
input is only in the fovea (with small amounts of motion detection
(eg) in the rest of the retina).

2. 14 million colours => 24 bits, not 16.

3. I stand by my figure (of ~500Mb/sec).

Nick Haines nickh@cs.cmu.edu
From: rose@acf9.nyu.edu (David Rose)
Newsgroups: rec.arts.sf.science
Subject: Re: Psychohistory
Date: 10 Apr 92 21:38:30 GMT
Organization: New York University

csmith@onetouch.COM (Craig Smith) writes:

>I have a major gripe with Foundation's Psychohistory.
>...
>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!

  Three things.

  1.  It was claimed that Hari Seldon (tho actually the Second Foundation)
      foresaw "critical periods" in the history of the First Foundation,
      which is when the following stories take place.  These were periods
      when something like a phase change might occur and the historical
      trends and society of the First Foundation shifted.  These were also
      times when the recorded image of Hari Seldon expressed relief because
      otherwise he doubted that anyone would be there to listen to the
      recordings.

  2.  Take a solution of supercooled water, i.e. below the freezing point.
      Now eventually that water is going to freeze, just a soon as it
      can find something to start the process.  Once it begins, the
      whole solution freezes quickly.  The individuals in the Foundation
      stories are like the particle which begins to freeze first.

  3.  In his Second Foundation, Asimov backs off from having Hari Seldon
      predict everything, and replaces an ongoing and active organization
      called the Second Foundation instead.  An active prescence would
      be able to correct predictions made and adjust their guidance
      accordingly.

>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.

  This is more a commentary upon history as an art form than the past.
In fact, since the end of the 19th century people have increasingly
written "social" histories, which focus upon popular trends and not
upon individuals.

>Any refutations? comments?


--
David Rose
Courant Institute of Mathematical Sciences
251 Mercer Street, New York, NY 10012
rose@math12.cims.nyu.edu
From: stevea@jab.tucson.az.us (Steve Albany)
Newsgroups: rec.arts.sf.science
Subject: Re: Dyson Sphere
Date: 8 Apr 92 18:51:04 GMT
Organization: Just Another Bbs. Tucson, AZ


        A Dyson Sphere is an artifical construct which incircles a star and 
traps its energy. The amount of available surface area is outrageous!
        I don't know if its really been in any books (I'm sure it has). Alot 
of people might jump and say Larry Niven's Ringworld, but a Ringworld is 
something entirely different..

        ================================================================
        |                    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   |
        ================================================================