Date: Fri, 28 Jul 1995 12:09:50 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: Realistic Space Campaign

>> The question is more elaborately addressed in
>> 
>> http://www.cs.tu-bs.de/~rhiemeir/life.html
>> 
>> About realistic aliens, read
>> 
>> http://www.cs.tu-bs.de/~rhiemeir/aliens.html
> 
>Hi, I have a quick question you might be able to answer. I'm
>writing a story for a homebrew sf-rpg where back in the 40s,
>the USA manages to capture itself an extra-terrestrial. Even
>assuming that the ET is carbon/water-based, 

Which is not unlikely at all, I think.

>	and even assuming
>that it can withstand our atmosphere (which may be a stretch,
>I dunno), 

Not so big a stretch, I think; I'd say that such a nitrogen/oxygen is
not a very exotic condition on worlds with carbon/water-based life.

>	how long do you think it could survive eating our
>food? We don't know what minerals/vitamins are necessary to
>sustain it or if they even exist in our ecosystem. Man was
>naturally adapted to eat what was available on Earth. The
>alien wasn't. How likely do you think it is that it could
>even metabolize our food (i.e., can a bullfrog metabolize
>an apple or a carrot or even a grain of rice?). You seemed
>knowledgable about this sort of stuff, so I thought I'd
>see what you thought.

This is a very interesting question, and not easy to answer.  The
point is that we don't know how many alternatives to the sorts of
molecules which Earth-based life is based on exist.

I assume that many of the more abundant organics we are composed of
are also found in other planets' life, but many more special are not.
This means that the ET probably won't find anything it needs on Earth.
Some vital molecules (such as some vitamins or amino acids) will miss
on Earth, while some other substances which occur in any Earth
organism might be poisonous to the ET.

Look at the vitamin B-12, for example.  I have seen a chemical formula
of a part of B-12 once, and it was complex like hell.  Chances that
B-12 can be found elsewhere are as good as zero.  Nevertheless, it is
essential to us.  It is very likely that other life forms will have
some equally essential, and equally unlikely molecules, which don't
exist on Earth.

This means that the ET must feed off something from its own home
world.  If it carried along something alive which produces everything
it needs and which can be grown on Earth (and be it in a laboratory),
the ET might survive.  Otherwise, it'll be in BIG trouble.

Anyway, the problems with an ET trying to find food on Earth are much
more hairy than any kind of incompatibility found on Earth.  There are
animals right here on Earth, which feed off things that are of no
nutrition value for us (e.g., wood or paper), or even things that
would kill us (I have read of lemurs whose daily ration of bamboo
contains enough cyanide to kill half a dozen humans, not to mention
life at oceanic geothermal vents, which essentially lives in *boiling
acid* strong enough to entirely dissolve a human body in a few minutes!).
And even those things are a breeze against the problems you run into
with food from another planet, I'd say.

I see that this issue is not properly covered by what is on the World
Wrights' Web right now.  I think I'll have to write something up in
that vein.  I am going to revise several things anyway.  For example,
I am not very happy with the current Stars, Planets and Life page,
which I think should be rewritten and broken up into several pages.


From: james vassilakos <jimv>
Subject: Re: Realistic Space Campaign
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Fri, 28 Jul 1995 14:01:39 -0700 (PDT)
 
> Look at the vitamin B-12, for example.  I have seen a chemical formula
> of a part of B-12 once, and it was complex like hell.  Chances that
> B-12 can be found elsewhere are as good as zero.  Nevertheless, it is
> essential to us.  It is very likely that other life forms will have
> some equally essential, and equally unlikely molecules, which don't
> exist on Earth.

Yes, this is what I was worried about. In this story I'm writing which
is going to be part of an sf-rpg's background fiction, a space alien
is in-effect captured by the U.S. government and held for a period of
time. They don't know enough about the critter's biological needs to
synthesize the alien's version of B-12, so my question then becomes,
how long do you think said alien will survive after capture? I.e.,
how long could a person survive without B-12?

Maybe this would be a better question to ask a nutritionist, but
do you think we're talking weeks, months, or years?

jimv@cs.ucr.edu 


From: james vassilakos <jimv>
Subject: Re: Realistic Space Campaign
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Wed, 2 Aug 1995 19:07:25 -0700 (PDT)
 
> Look at the vitamin B-12, for example.  I have seen a chemical formula
> of a part of B-12 once, and it was complex like hell.  Chances that
> B-12 can be found elsewhere are as good as zero.  Nevertheless, it is
> essential to us.  It is very likely that other life forms will have
> some equally essential, and equally unlikely molecules, which don't
> exist on Earth.
 
Well, just in case you've been looking into this, I've learned from
some netters on sci.med.nutrition that many vitamins are stored in the
body in the event that some form of depletion might occur. In the case
of B-12, it seems it would take 3-5 years for the body's reserves to
be depleted. For some other vitamins, the timespan is only a few months
before clinical effects can be shown, although the immune system may
be effected in only weeks.

It might be useful to compile a chart detailing the value of each
vitamin, how long the body can go without, how likely it is to be
found "out there" on your random "Class-M" (haha), how easily it
can be synthesized artificially (they probably all can be, I'd
suspect), and most importantly, the effects of long-term depletion
and time-to-fatality.

Of course, the short question is still, how long can a human
get away with eating alien food and vice-versa before (a)
malnutrition sets in and (b) death results. Figure we should
just write up a random table and be done with it? :-)

jimv@cs.ucr.edu


Date: Thu, 3 Aug 1995 12:18:01 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: Vitamins (was Re: Realistic Space Campaign)

>> Look at the vitamin B-12, for example.  I have seen a chemical formula
>> of a part of B-12 once, and it was complex like hell.  Chances that
>> B-12 can be found elsewhere are as good as zero.  Nevertheless, it is
>> essential to us.  It is very likely that other life forms will have
>> some equally essential, and equally unlikely molecules, which don't
>> exist on Earth.
> 
>Well, just in case you've been looking into this, I've learned from
>some netters on sci.med.nutrition that many vitamins are stored in the
>body in the event that some form of depletion might occur. In the case
>of B-12, it seems it would take 3-5 years for the body's reserves to
>be depleted. For some other vitamins, the timespan is only a few months
>before clinical effects can be shown, although the immune system may
>be effected in only weeks.
>
>It might be useful to compile a chart detailing the value of each
>vitamin, how long the body can go without, how likely it is to be
>found "out there" on your random "Class-M" (haha), how easily it
>can be synthesized artificially (they probably all can be, I'd
>suspect), and most importantly, the effects of long-term depletion
>and time-to-fatality.

I think that humans (and probably all lifeforms everywhere) need more
of a particular vitamin, the more `likely' the molecule is.  We need
only very small amounts of B12, and can store it quite a long time,
but we run out of C quite quickly, for example.  The chance that
we'll find vitamin C on a random planet, however, is much larger than
that we find vitamin B12 there.  I think all known vitamins have been
synthesized, even B12; however, with the more complex ones, the
synthesis is far too expensive, and so far only done in laboratory scale.

>Of course, the short question is still, how long can a human
>get away with eating alien food and vice-versa before (a)
>malnutrition sets in and (b) death results. Figure we should
>just write up a random table and be done with it? :-)

Hmmm, I think that *unprocessed* alien food will lead to trouble quite
quickly, as it is very likely to contain some toxic substances.  To
live off alien stuff, we would have to process it heftily, to remove
unhealthy alien ingredients and add some vitamins etc. which are
missing (though the latter can also be complemented through pills,
imported or hydroponically grown oranges, or similar means).

The captured alien, however, is at an important disadvantage against
human settlers on alien planets.  We *know* which vitamins we need,
and can bring along the missing stuff, or build production
facilities.  The alien might also know what it needs, but *we* don't.
So we can't give it what it needs, and can't tell what is missing to him.
His physiology is alien, so if some clinical effect occurs in that
alien, we can't tell why.  We even don't know what is normal.  If the
alien's body temperature is measured to be 45 degrees C, is this its
normal temperature?  Or is its normal temp. 43, which means the alien
has light fever, or is it 35, which means very *severe* fever, or
perhaps 50 or more?


From: james vassilakos <jimv>
Subject: more questions
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Fri, 4 Aug 1995 17:32:49 -0700 (PDT)
 
> >Of course, the short question is still, how long can a human
> >get away with eating alien food and vice-versa before (a)
> >malnutrition sets in and (b) death results. Figure we should
> >just write up a random table and be done with it? :-)
> 
> Hmmm, I think that *unprocessed* alien food will lead to trouble quite
> quickly, as it is very likely to contain some toxic substances.  To
> live off alien stuff, we would have to process it heftily, to remove
> unhealthy alien ingredients and add some vitamins etc. which are
> missing (though the latter can also be complemented through pills,
> imported or hydroponically grown oranges, or similar means).

So what you're telling me here is that if I feed an apple to Mister
ExtraTerrestrial, he's gonna be puking his guts out within the hour.
Hmmm... poses severe difficulties in terms of keeping a captured
alien alive, particularly one you know very little about.

I have two other topics I'd like to discuss with you. The first may
seem trivial, but I wanted your opinion never the less. It concerns
our basic outward physiology. How do I explain this? Whenever you
see aliens in movies or on television, they are either humans in
make-up, or they are animal-like. I know the humans in make-up
syndrome is totally bogus, but what about the animal-like
syndrome? For example, almost any land-based animal I can think
of (aside from your arachnids and insects and starfish, of course)
has two arms, two legs, not more than five fingers/digits on any
single of these appendages with five being a fairly common number.
For example, lizards (which are obviously not even mammals) have
two arms, two legs, and a total of twenty digits... just like humans.
Life on this planet seems, then, remarkably similar. Is it possible
that this design is "popular" among aliens as well? This has
far-reaching implications. For example, the reason our numbering
system is base-ten probably has something to do with the fact that
we have ten fingers. If "most" sentient aliens are in the same
predicament because this "basic-body-design" is "popular" on some
"nature/biological" level, then it is not too unlikely that their
numbering systems will be base-ten also. In short, do you think
this "basic-body-design" which seems so popular on earth is
popular for a reason, or do you think it is just an accident, and
that aliens with four arms or six arms or twenty arms and twenty
fingers on each of them is just as likely?

My second question has to do with the carbonate circuit process
which you outlined in your one article on the web. Do you have
any suspicions about whether or not humankind is screwing around
so much with the environment that we might be triggering either
a runaway albedo-cycle (deep-freeze) or a runaway greenhouse
cycle? I've heard (just a rumor) that we've managed to kill off
some 70% of the oceanic plankton, and our efforts at deforestation
in the Amazon are now popular-knowledge. I've even heard that we've
heated the globe a few degrees (though this is controversial).
I'm wondering if we've had an impact on the carbon-dioxide
levels in the atmosphere which you make out to be the center-stage
of global temperature control. Has CO2 dropped on a percentage
basis in the last, say, fifty years? Basically, I'm trying to
determine the likelihood that we've tumbling ourselves off the
edge of a big environmental cliff.


Date: Mon, 7 Aug 1995 12:44:16 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: more questions
 
>> >Of course, the short question is still, how long can a human
>> >get away with eating alien food and vice-versa before (a)
>> >malnutrition sets in and (b) death results. Figure we should
>> >just write up a random table and be done with it? :-)
>> 
>> Hmmm, I think that *unprocessed* alien food will lead to trouble quite
>> quickly, as it is very likely to contain some toxic substances.  To
>> live off alien stuff, we would have to process it heftily, to remove
>> unhealthy alien ingredients and add some vitamins etc. which are
>> missing (though the latter can also be complemented through pills,
>> imported or hydroponically grown oranges, or similar means).
>
>So what you're telling me here is that if I feed an apple to Mister
>ExtraTerrestrial, he's gonna be puking his guts out within the hour.

Yes, for example.  Much more likely than that he enjoys it.

>Hmmm... poses severe difficulties in terms of keeping a captured
>alien alive, particularly one you know very little about.

Exactly!

>I have two other topics I'd like to discuss with you. The first may
>seem trivial, but I wanted your opinion never the less. It concerns
>our basic outward physiology. How do I explain this? Whenever you
>see aliens in movies or on television, they are either humans in
>make-up, or they are animal-like. I know the humans in make-up
>syndrome is totally bogus, but what about the animal-like
>syndrome? For example, almost any land-based animal I can think
>of (aside from your arachnids and insects and starfish, of course)
>has two arms, two legs, not more than five fingers/digits on any
>single of these appendages with five being a fairly common number.
>For example, lizards (which are obviously not even mammals) have
>two arms, two legs, and a total of twenty digits... just like humans.
>Life on this planet seems, then, remarkably similar. Is it possible
>that this design is "popular" among aliens as well? 

I don't think so.  Mammals, birds, reptiles and amphibia all had a
common ancestor, which happened to have four limbs, and five digits
per limb.  Thus, all land-living vertebrates share the same numbers of
limbs and digits, unless they have reduced them afterwards.

Arachnids, insects, starfish etc. do not share the same common
ancestor, but developed their limbs independently from vertebrates,
thus having different numbers of limbs.

>	This has
>far-reaching implications. For example, the reason our numbering
>system is base-ten probably has something to do with the fact that
>we have ten fingers. If "most" sentient aliens are in the same
>predicament because this "basic-body-design" is "popular" on some
>"nature/biological" level, then it is not too unlikely that their
>numbering systems will be base-ten also. In short, do you think
>this "basic-body-design" which seems so popular on earth is
>popular for a reason, or do you think it is just an accident, and
>that aliens with four arms or six arms or twenty arms and twenty
>fingers on each of them is just as likely?

I think it is an accident.  Aliens might just as well have six, eight
or even more limbs (even numbers seem to be preferred, with the
exception of starfish; but not even this rule can be safely applied to
aliens: perhaps their symmetry is trilateral instead of bilateral,
thus having 3, 6, 9, 12, or 15 limbs).  The number of digits might
also vary, from two to about twenty, perhaps, if we can speak of
digits at all.  Perhaps they have tentacles which they can wind around
objects they are going to manipulate, or whatever.

It might however be possible that some numbers are more advantageous
than other.  I can imagine four- or six-limbed tool-using sophonts
better than 38-limbed ones.  But this might just be human prejudice.

With our limb and digit numbers being accidental, there is of course
no point in assuming that base-ten counting etc. is natural to all
intelligent beings in space.  It's not.  A three-handed being with four
fingers per hand will consider base 12 natural, for example.

Even symbols they use will be different.  Cross-like symbols are very
widespread in human culture, perhaps because a cross has four
`limbs'.  Many ethnologists assume that the cross symbol reflects our
four-limbedness.  The pentagram perhaps reflects the fivefoldness of
our fingers, but perhaps also the human body, with the top point
representing the head, the upper sideways points the arms, and the
lower points the legs.  A six-limbed species might prefer hexagonal
symbols (six-rayed stars, and their like).

>My second question has to do with the carbonate circuit process
>which you outlined in your one article on the web. Do you have
>any suspicions about whether or not humankind is screwing around
>so much with the environment that we might be triggering either
>a runaway albedo-cycle (deep-freeze) or a runaway greenhouse
>cycle? I've heard (just a rumor) that we've managed to kill off
>some 70% of the oceanic plankton, and our efforts at deforestation
>in the Amazon are now popular-knowledge. I've even heard that we've
>heated the globe a few degrees (though this is controversial).
>I'm wondering if we've had an impact on the carbon-dioxide
>levels in the atmosphere which you make out to be the center-stage
>of global temperature control. Has CO2 dropped on a percentage
>basis in the last, say, fifty years? 

It has not DROPPED, it has INCREASED, thus warming the planet.
This comes from burning fossile fuels, and deforestation.  The
carbonate circuit works against this; with our planet becoming warmer,
the water circuit accelerates and washes more CO2 out of the
atmosphere.  But we can't rely on it.  This mechanism is very slow; we
spill out CO2 in so big amounts that the carbonate circuit cannot keep
pace.  If we stop spilling CO2 in time, however, the circuit will
smooth it out, and within a few hundred years, we are back at the
original 0.028% and the original temperatures.  But if we drive the
thing too far, we'll run into an ecological catastrophe.  I don't
think this will render the planet entirely uninhabitable, but many
species will die out, and human life will be very miserable (if we
humans don't die out).  We would die long before Earth goes over the
brink, and when we die out, the pollution stops.  (However, it might
be possible that some runaway side effects blow the lid.)

>	Basically, I'm trying to
>determine the likelihood that we've tumbling ourselves off the
>edge of a big environmental cliff.

See above.  Even if Earth's biosphere is not completely destroyed, it
will be severely messed up.  Circuit processes excel at smoothing out
random burps, but are often very easily broken by long-lasting
pressure towards one direction.  We should try to limit our CO2 emission
as soon as possible.


From: james vassilakos <jimv>
Subject: Re: more questions
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Thu, 17 Aug 1995 14:55:29 -0700 (PDT)

Speaking about the carbon-cycle and global warming, you wrote: 
> Even if Earth's biosphere is not completely destroyed, it
> will be severely messed up.  Circuit processes excel at smoothing out
> random burps, but are often very easily broken by long-lasting
> pressure towards one direction.  We should try to limit our CO2 emission
> as soon as possible.
 
This is the basic thesis behind the SF-game that I'm doing. Human
intelligence was genetically engineered by aliens some 30-50k years
ago. There was a species that believed in "uplifting" other species,
a practice now held to be highly questionable and occasionally
catastrophic. In any case, because humans didn't slowly develop
intelligence as did other races, we didn't have the time to study
our planet and our society before technological advances led us to
global warfare and a decaying biosphere. The aliens now regard us
as a barbaric curiosity, the only race known to them to have
tapped nuclear power before developing supersonic flight. They
also live in fear of the day that we should ever achieve interstellar
travel, as they have had problems with "upliftees" in the past.
Nonetheless, they are comforted by the fact that we are destroying
our own world with CO2 emissions and that our civilization will
most likely collapse from within before we ever manage to get off
the planet. Of course, the race that uplifted us in the first place
wants to lend a helping hand to protect our species for what little
good they see in us, however, they are prevented from doing so by
the coalition as a whole, and there is at least one other race
out there which would very much like to drop some pretty awful
weapons on our heads just to make sure we never pose them any
threat. In short, humanity is an unwanted child.

So, for purposes of depicting future events on earth, how long
do you think it'll take before the general populace begins to
realize the threat posed by global warming? Envisioning some
plausible advanced technology, what ways do you think the
more friendly of races might be able to help (even if they
aren't allowed to politically)? And, do you think we'll be
able to halt or even seriously curb CO2 emissions without
causing civilization to come crashing down around us, and
if not, how long do you think it'll take before we begin
suffering from mass-starvation or whatever due to the changes
in global climate?

Hard questions, I agree, but so far you're the best person
I've found who can make educated guesses as to this stuff.

One other question, which you can feel free to disregard
if you think I'm being dumb about the whole thing. I'm
trying to come up with a very simplistic planetary
catagorization scheme so that I can represent entire
worlds with just one byte of data (and then let the
individual world designers flesh out the planet in
whatever detail they want to provide). Here's the
system so far...

   Solar Companion: Not technically a world but not the main star
      or even a part of the close-binary pair.
   Gas Giant: Fairly obvious. Great for wilderness refueling if
      we're using hydrogen to get around.
   Greenhouse: A world gone to hell because of too much
      greenhouse gases.
   Planetoid: A very small world, generally. Not necessarily
      round. No atmosphere to speak of. Composed of rock or ice.
   Belch Ball: You don't want to breath the atmosphere. Probably
      corrosive in the extreme.
   Primordial: A very young world. Atmosphere varies.
      Geologically instable. Lots of volcanos and magma seas.
   Desert World: Generally a non-breathable atmosphere, but there
      may be water and oxygen tied up as ice crystals in the soil.
   Exotic: Not an atmosphere you want to breath, maybe because it
      contains poisonous gasses or even lethal micro-organisms.
      But not a place you can't otherwise walk around, so long as
      you have your own oxygen supply. Note that an alien
      ecosystem may well be thriving.
   Magma Ball: Ouch, this place is hot.
   Vacuum Ball: Like the moon, essentially. Lots of rock. No
      atmosphere.
   Shallow World: Has atmosphere but not enough to breath, at
      least not without descending to a very deep altitude. Mars
      could be an example.
   Dead World: The place is certainly colonizable, but for one
      reason or another, life either never existed or went
      extinct long ago. Maybe the sun flared and knocked out the
      entire ecosystem. Or maybe a slew of meteors struck,
      churning up enough dust that the sun was blotted out for
      decades. Most likely, the atmosphere is not breathable.
   Garden World: Earth is a prime example. Not only can you
      breath the atmosphere without mechanical aid, but life,
      either native or transplanted, thrives in abundance.
   Water World: Over 90% covered by water and ice. Possibly a
      breathable atmosphere. Possibly a teaming native ecosystem
      which got evolutionarily stuck due to the total lack of any
      freestanding continents.
   Ice Planet: May have a breathable atmosphere so long as there
      is the eco-system to support it. More likely a dead planet
      without a breathable atmosphere.

Do you see anything wrong... anything that should be changed or
added or whatever?

Thanks lots for all your input. I really appreciate it!


Date: Fri, 18 Aug 1995 12:29:32 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: more questions

On Thu, 17 Aug 1995 14:55:29 -0700 (PDT) you wrote:
>Speaking about the carbon-cycle and global warming, you wrote: 
>> Even if Earth's biosphere is not completely destroyed, it
>> will be severely messed up.  Circuit processes excel at smoothing out
>> random burps, but are often very easily broken by long-lasting
>> pressure towards one direction.  We should try to limit our CO2 emission
>> as soon as possible.
> 
>This is the basic thesis behind the SF-game that I'm doing. 

Neat idea!

>	Human
>intelligence was genetically engineered by aliens some 30-50k years
>ago.

According to current paleontological evidence, the first group of full-
fledged humans popped up in East Africa about 150k years ago, but this
is merely adjustment of figures.  The group seems to have been quite
small (about 10000 individuals), thus could well have been the result
of some weird experiment carried out by star-faring aliens.

Note that the alternative `multiregional' hypothesis, according to
which the different `races' reached Homo sapiens level simultaneously
after having spread about the continents more than 0.5M years ago, is
as good as dead.  All `evidence' for this hypothesis has turned out to
be either misinterpreted or forged.  And forget about bone-headed
arguments of multiregionalists of `misclaibrated genetic clocks' and
all that stuff.  If multiregionalism was true, this would mean that
`Eve' lived 2 million years ago (the oldest Homo erectus specimens
from Java are 1.7 million years old!), but this would infer that the
lines of humans and chimpanzees had diverged 70 million years ago!

>	There was a species that believed in "uplifting" other species,
>a practice now held to be highly questionable and occasionally
>catastrophic. 

Anders Sandberg has told me that there have been several more or less
sanctioned murders of species "for the common good"?

>	In any case, because humans didn't slowly develop
>intelligence as did other races, we didn't have the time to study
>our planet and our society before technological advances led us to
>global warfare and a decaying biosphere. The aliens now regard us
>as a barbaric curiosity, the only race known to them to have
>tapped nuclear power before developing supersonic flight. They
>also live in fear of the day that we should ever achieve interstellar
>travel, as they have had problems with "upliftees" in the past.

Bleak prospects :-(

>Nonetheless, they are comforted by the fact that we are destroying
>our own world with CO2 emissions and that our civilization will
>most likely collapse from within before we ever manage to get off
>the planet. Of course, the race that uplifted us in the first place
>wants to lend a helping hand to protect our species for what little
>good they see in us, however, they are prevented from doing so by
>the coalition as a whole, and there is at least one other race
>out there which would very much like to drop some pretty awful
>weapons on our heads just to make sure we never pose them any
>threat. In short, humanity is an unwanted child.

Similar to the `wolfling' status in Brin's universe, I guess.

I don't know whether I have told you about my campaign already, but I
work with the idea that an alien species abducted humans to remote
planets about 50-100k years ago for unknown reasons.  The result is a
mess of several dozen human nations at different tech levels (they
were left in stone age when the aliens vanished mysteriously).

Some of these nations are quite weird.  One, having become tall and
slender by living on a planet with low gravity (about 0.8 g), have
developed a naturalist life style, and employ creative energy to
accomplish magical effects.  Another group lives on a high-gravity
(1.4 g), metal-rich world.  They are rather short and squat, and
inclined to hard technology (mining, starship engineering, etc.).  
I am also considering a group with an aquatic life style.

Human technology: FTL stardrives, nanotechnology, no AIs built on purpose,
but some large computer networks have awakened.  No FTL `radio'.
Not much cybertech or posthumanism.

These scattered humans are actually a plot device.  It is the only
believable way to set up strange humanoid nations.

Of course, there are also a few non-human aliens.  The Elder Lords
(those who have abducted the humans) are gone, and some people assume
that the Jaig are their degenerate descendants, but they are almost
certainly wrong.  The Jaig are a mysterious race which I have modelled
after the `Greys' from UFO folklore.  They are small, amphibious,
grey-skinned bipeds.  They have some weird ultra-tech gadgets, among them
disc-shaped starships which can easily out-maneuver even the best human
starships.  They routinely do things which are deemed impossible by
even the most advanced human scientific theories.  Though being
technically utterly powerful, they seem to be very few in number and
not inclined to power.  They rather seem to make fun of us by playing
all sorts of tricks on humans.

Another important race are the Kla.  They are a very old, wise race,
which has the weird practice of `promoting' other species.  This is
somehow similar to uplifting, but does not involve genetic surgery; it
is rather teaching culture and technology.  The `Family' of species
promoted by the Kla and their client races (some of which have
promoted their own client races) consists of about 15 species.  Among
them is even one group of humans: the 'Nbuur.  It is unknown why they
do this.  Some people speculate that it is an old drive to secure the
future existence of their culture, perhaps caused by the fact that
their home world orbits an F6 star which is reaching the end of its
main sequence lifetime.  Some people assume that they have themselves
been promoted by a species which has disappeared long time ago.

Then there are a few very mysterious groups: the immaterial Taavi, which
are just sentient fields of creative energy (on the subjest of
creative energy, cf. http://www.cs.tu-bs.de/~rhiemeir/creative-energy.html).
The Harvesters are something from Anders's idea forge (but I coined
the name).  They are material, but incredibly alien and *very* old.
They are around for at least 5000 million years, and they are
colonizing not planets, but *stars*.  They build Dyson spheres
*within* stars.  Actually, all main sequence stars seem to be
colonized by the Harvesters this way, and some people assume that the
main sequence is not a natural phenomenon at all, but a kind of
artificial life prolongation by the Harvesters!

>So, for purposes of depicting future events on earth, how long
>do you think it'll take before the general populace begins to
>realize the threat posed by global warming? 

At least in some parts of the world, the general populace has already
begun to realize, but it catches on slowly.  I consider it not
unlikely that in Europe, a non-violent ecologist-social-democratic
revolution catches on in the first decades of the 21st century.
Unfortunately, it doesn't look like that in the U.S., let alone the
Far East.  It will get worse, with the fascist regime in China pushing
ahead large-scale industrialization at all costs.

>	Envisioning some
>plausible advanced technology, what ways do you think the
>more friendly of races might be able to help (even if they
>aren't allowed to politically)?

If you are thinking of some kind of super-tech miracle cure to our
planet: forget it.  But they might try to influence politics on Earth
in favour to environmentalist groups.

>	And, do you think we'll be
>able to halt or even seriously curb CO2 emissions without
>causing civilization to come crashing down around us, and
>if not, how long do you think it'll take before we begin
>suffering from mass-starvation or whatever due to the changes
>in global climate?

I think it could be done, but it definitely involves a somewhat
painful transition period.  Rebuild energy economy to replace fossile
fuels by renewable sources.  This includes replacing gasolin as car
fuel by things like rape oil, alcohol (from fermentation) or hydrogen
(obtained by electrolysis of water, using power from solar or wind
plants).  Improve energy efficiency.  The 100 miles-per-gallon car is
a viable option within the next 10 years.  It is estimated that energy
consumption in the U.S. could be cut by 75% without significant loss
of life quality!  (In Europe, this dactor is lower because in Europe,
energy is already used more efficiently -- smaller cars, less
air-conditioning, more widespread use of power-saving lamps, etc.  But
even here it could at least be cut by half.)

If this change doesn't happen, things will look VERY bad within 30 or
50 years.  Most of the U.S., many parts of China and all of Southern
Europe will turn into deserts.  Central Europe will have a
mediterranean climate.  Canada, Scandinavia and Siberia will have less
cold winters, but the benefits from this will be insubstantial.

>Hard questions, I agree, but so far you're the best person
>I've found who can make educated guesses as to this stuff.

People who *believe* that they are knowledged are copious, but those
who really know are few.  I *hate* all those dumbheads coming in via
AOL, Compu$erve or Prodigy (no, not ALL of these people are dumbheads,
but most are, probably because this is the dumbest way to access the
Internet I can imagine).

[planetary classification system omitted]

>Do you see anything wrong... anything that should be changed or
>added or whatever?

The scheme makes sense.  I have experimented with many self-designed
ones, but most didn't convince me.  One problem is that most systems
either lump too many different types in too few categories, create a
complicated mess of lots of types, or both.  The other problem is that
we don't know what is typical, and of most classes, we have just one
example (or even less), which might just as well be a unique freak,
unparalleled by anything in the Universe.

>Thanks lots for all your input. I really appreciate it!

Thank you too!


From: james vassilakos <jimv>
Subject: Re: more questions
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Mon, 21 Aug 1995 15:49:04 -0700 (PDT)
 
> On Thu, 17 Aug 1995 14:55:29 -0700 (PDT) you wrote:
> According to current paleontological evidence, the first group of full-
> fledged humans popped up in East Africa about 150k years ago, but this
> is merely adjustment of figures.  The group seems to have been quite
> small (about 10000 individuals), thus could well have been the result
> of some weird experiment carried out by star-faring aliens.

I didn't really want to make the aliens that old. I was thinking of
making the current group just older than human civilization (in the
most basic sense... once humans showed they were significantly smarter
than animals via use of symbols and more advanced tool fabrication as
well as agriculture and the ability to plan for the future in a
reasoning rather than instinctual capacity). Able to stick a
guestimated date on this?

> >	There was a species that believed in "uplifting" other species,
> >a practice now held to be highly questionable and occasionally
> >catastrophic. 
> 
> Anders Sandberg has told me that there have been several more or less
> sanctioned murders of species "for the common good"?

Yeah, we've been talking about this for some time now (since May). I
have all our correspondence saved, and I may provide it with the
game under "development notes" just so people can see the process
we went through. By the way, I'd very much like to include your
two web essays...

http://www.cs.tu-bs.de/~rhiemeir/life.html
http://www.cs.tu-bs.de/~rhiemeir/aliens.html

I pulled both down as text documents, and with your permission,
I'd like to include them in the "development notes" section.

> I don't know whether I have told you about my campaign already, but I
> work with the idea that an alien species abducted humans to remote
> planets about 50-100k years ago for unknown reasons.  The result is a
> mess of several dozen human nations at different tech levels (they
> were left in stone age when the aliens vanished mysteriously).

Sounds a bit like Traveller. The seeding idea is pretty common in
SF. The thing I never liked about it was the unusual circumstance
that Earth (our world) was the one they choose to use as the source.
It seemed a bit too unlikely. A bit contrived. I want to generate
a setting which is both fun and which can be rationalized naturally.
Something that'll make players nod and say, "That makes sense."
 
> These scattered humans are actually a plot device.  It is the only
> believable way to set up strange humanoid nations.

Yeah, precisely. Well, you can also assume a far-future setting
where Earth is destroyed but humans have scattered across the
galaxy and been removed from each other for several million
years. You might also want to assume a fairly close technology
ceiling, however, as well as assuming a "Vacant Universe" so
that humans can spread out at their leisure. Human-like aliens
could be the result of both evolution and genetic toying.
 
> >	Envisioning some
> >plausible advanced technology, what ways do you think the
> >more friendly of races might be able to help (even if they
> >aren't allowed to politically)?
> 
> If you are thinking of some kind of super-tech miracle cure to our
> planet: forget it.  But they might try to influence politics on Earth
> in favour to environmentalist groups.

That would be difficult to do without the sanction of the coalition.
Spies would catch on to what they are doing and effectively realize
they're breaking the non-interference agreement. I was figuring that
by the time the humans realized their predicament and had mustered
the political will to do something about it, it would be too late.
I was thinking more in terms of some sort of atmospheric processing
technology... something to scoop massive amounts of CO2 out of a world's
atmosphere. Of course, the humans would try to get it somehow once
they learn that it exists and that could be the focus of an adventure.


Date: Tue, 22 Aug 1995 14:59:44 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: more questions

You wrote:
>> On Thu, 17 Aug 1995 14:55:29 -0700 (PDT) you wrote:
>> According to current paleontological evidence, the first group of full-
>> fledged humans popped up in East Africa about 150k years ago, but this
>> is merely adjustment of figures.  The group seems to have been quite
>> small (about 10000 individuals), thus could well have been the result
>> of some weird experiment carried out by star-faring aliens.
>
>I didn't really want to make the aliens that old. I was thinking of
>making the current group just older than human civilization (in the
>most basic sense... once humans showed they were significantly smarter
>than animals via use of symbols and more advanced tool fabrication as
>well as agriculture and the ability to plan for the future in a
>reasoning rather than instinctual capacity). Able to stick a
>guestimated date on this?

Agricultural civilization started about 10000 years ago, I think.

>> >	There was a species that believed in "uplifting" other species,
>> >a practice now held to be highly questionable and occasionally
>> >catastrophic. 
>> 
>> Anders Sandberg has told me that there have been several more or less
>> sanctioned murders of species "for the common good"?
>
>Yeah, we've been talking about this for some time now (since May). I
>have all our correspondence saved, and I may provide it with the
>game under "development notes" just so people can see the process
>we went through. By the way, I'd very much like to include your
>two web essays...
>
>http://www.cs.tu-bs.de/~rhiemeir/life.html
>http://www.cs.tu-bs.de/~rhiemeir/aliens.html
>
>I pulled both down as text documents, and with your permission,
>I'd like to include them in the "development notes" section.

Feel free to do so, as long as you include a statement that the
material is written by me.

>> I don't know whether I have told you about my campaign already, but I
>> work with the idea that an alien species abducted humans to remote
>> planets about 50-100k years ago for unknown reasons.  The result is a
>> mess of several dozen human nations at different tech levels (they
>> were left in stone age when the aliens vanished mysteriously).
>
>Sounds a bit like Traveller. The seeding idea is pretty common in
>SF. The thing I never liked about it was the unusual circumstance
>that Earth (our world) was the one they choose to use as the source.
>It seemed a bit too unlikely. A bit contrived. I want to generate
>a setting which is both fun and which can be rationalized naturally.
>Something that'll make players nod and say, "That makes sense."

There is a reason why Earth was chosen, and not a neighbouring planet:
only Earth offered something which was of interest to the aliens.
There would have been little point in shipping around Arlian clawtoads,
Kamonian squirrel-bats or Hairunese swamp spiders.
I assume that the emergence of a sentient, tool-using lifeform is a
fairly unusual event, and it is unlikely that there is a species on
a stage equivalent to stone-age Homo sapiens on another planet within,
let's say, 100 light-years.  On most planets there is either nothing
ripe, or an advanced civilization.

>> These scattered humans are actually a plot device.  It is the only
>> believable way to set up strange humanoid nations.
>
>Yeah, precisely. Well, you can also assume a far-future setting
>where Earth is destroyed but humans have scattered across the
>galaxy and been removed from each other for several million
>years. You might also want to assume a fairly close technology
>ceiling, however, as well as assuming a "Vacant Universe" so
>that humans can spread out at their leisure. Human-like aliens
>could be the result of both evolution and genetic toying.

Yes, that also works.  The reason why I decided to go for scattered
humans is that I wanted to set the campaign in a rather near future
(about the middle of the 22nd century), because this way, I could
introduce Earth with recognizable cultures into the campaign.

In my astrography, Earth is not set in the center of the area
inhabited by scattered humans, but in a rather peripheral position,
which gives us a `back yard' to colonize.
 
>> >	Envisioning some
>> >plausible advanced technology, what ways do you think the
>> >more friendly of races might be able to help (even if they
>> >aren't allowed to politically)?
>> 
>> If you are thinking of some kind of super-tech miracle cure to our
>> planet: forget it.  But they might try to influence politics on Earth
>> in favour to environmentalist groups.
>
>That would be difficult to do without the sanction of the coalition.
>Spies would catch on to what they are doing and effectively realize
>they're breaking the non-interference agreement. I was figuring that
>by the time the humans realized their predicament and had mustered
>the political will to do something about it, it would be too late.

Perhaps the Coalition is secretely supporting anti-environmentalist groups?

>I was thinking more in terms of some sort of atmospheric processing
>technology... something to scoop massive amounts of CO2 out of a world's
>atmosphere. Of course, the humans would try to get it somehow once
>they learn that it exists and that could be the focus of an adventure.

They could set up underground algae farms to remove the excess CO2 from
the atmosphere (scooping off with spacecraft seems less likely).  The algae
could receive the light they need either through orbital mirrors which
reflect sunlight down volcanic shafts, or lamps powered by geothermy,
catalytic fusion, or whatever.  The usual terraforming stuff.



From: james vassilakos <jimv>
Subject: Re: more questions
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Wed, 23 Aug 1995 17:32:36 -0700 (PDT)
 
> >I pulled both down as text documents, and with your permission,
> >I'd like to include them in the "development notes" section.
> 
> Feel free to do so, as long as you include a statement that the
> material is written by me.

Of course. That goes without saying. One question though...
how do you want your first name spelled on the selection menu...
Jrg, Jvrg, or Joerg?
 
> They could set up underground algae farms to remove the excess CO2 from
> the atmosphere (scooping off with spacecraft seems less likely).  The algae
> could receive the light they need either through orbital mirrors which
> reflect sunlight down volcanic shafts, or lamps powered by geothermy,
> catalytic fusion, or whatever.  The usual terraforming stuff.

I dunno. It would have to be pretty huge. I was thinking of maybe some way
to inject chemicals useful to plankton into the oceans so that more could
produce. You'd think that more would produce in warm waters, however, I
guess that the warm water layer somehow prevents nutrients from reaching
the plankton from the sea floors (just reading an old article on the
topic). Makes me wonder if the drop of in plankton that I've heard rumors
about (can you confirm or deny?) is related to global warming and the CO2
surplus. If so, that would be pretty awful.  Talk about runaway greenhouse.

Oh, by the way, the computers here will be going down on the 24th and 25th
due to lack of air conditioning, so if my mail bounces during those days,
that's why.

Also, here's the most recent version of that planetary classification
scheme... final call for comments.

   Solar Companion: Not technically a world but not the main star
      or even a part of the close-binary pair.
   Gas Giant: Fairly obvious. Great for wilderness refueling if
      we're using hydrogen to get around.
   Greenhouse: A world gone to hell because of too much
      greenhouse gases (ala Venus).
   Planetoid: Generally a very small world which is not part of
      an asteroid belt. Not necessarily round. Could be a
      captured planet. No atmosphere. Composed primarily of rock.
   Belch Ball: Lifeless terrestrial planet with a poisonous
      (possibly even corrosive) atmosphere.
   Primordial: A very young world. Atmosphere varies.
      Geologically instable. Lots of volcanos and magma seas.
   Desert World: Generally a non-breathable atmosphere, but there
      may be water and oxygen tied up as ice crystals in the
      soil. May be volcanically active. Probably on its way to
      becoming a shallow world.
   Exotic: Not an atmosphere you want to breath, maybe because it
      contains poisonous gasses or even lethal micro-organisms,
      but not a place you can't otherwise walk around, so long as
      you have your own oxygen supply. Note that an alien
      ecosystem may well be thriving. Many alien homeworlds will
      be exotics.
   Magma Ball: Ouch, this place is hot. This planet is either
      very close to the primary or is on its way to becoming a
      primordial world.
   Vacuum Ball: Like the moon, essentially. Lots of rock. No
      atmosphere. Too big to be called a planetoid.
   Shallow World: Has atmosphere but not enough to breath, at
      least not without descending to a very deep altitude. Mars
      could be an example.
   Dead World: The place is certainly colonizable, but for one
      reason or another, life either never existed or went
      extinct in the recent past. Perhaps the sun flared and
      knocked out the entire ecosystem, or maybe a slew of
      meteors struck, churning up enough dust that the sun was
      blotted out for several decades. Almost certainly, the
      atmosphere is not breathable. In any case, the world is
      either slowly freezing or heating up and becoming a
      greenhouse.
   Garden World: Earth is a prime example. Not only can you
      breath the atmosphere without mechanical aid, but life,
      either native or transplanted, thrives in abundance.
   Water World: Over 90% covered by water and ice. Possibly a
      breathable atmosphere. Possibly a teaming native ecosystem
      which got evolutionarily stuck due to the total lack of any
      freestanding continents.
   Liquid World: Surface predominantly covered by ammonia or
      liquid methane. May contain an alien ecosystem.
   Ice Planet: May have a breathable atmosphere so long as there
      is the ecosystem to support it. More likely a dead planet
      without a breathable atmosphere.
   Ice Pebble: Like a planetoid, but composed primarily of ice.
      Usually found only beyond the star's biozone.
   Asteroid: Like a planetoid, only part of an asteroid belt.
   Unusual: This world cannot be placed in any of the previously
      defined categories. It may be an artificial planet or
      perhaps a fluke of nature. GM's discretion advised.


Date: Thu, 31 Aug 1995 18:14:05 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: more questions

You wrote:
>Of course. That goes without saying. One question though...
>how do you want your first name spelled on the selection menu...
>Jrg, Jvrg, or Joerg?

Ah yes, the well-known umlaut problem.  The correct form has an
o-umlaut as the second letter, but this always causes trouble.  I wish
everyone used ISO Latin-1 and 8-bit-clean software!

I don't know what the first two were like when you sent them, but
they arrived as `Jrg' and `Jvrg'.  `Jvrg' is what you get when the
high bit is stripped off from the o-umlaut, and `Jrg' is missing that
character entirely.  `Joerg' is an alternative spelling used on 7-bit
media; in any case, it is better than any kind of mutilated form like
`Jrg' or `Jvrg'.

(Side note: while machines tend to mangle my first name, people tend to
mangle my second name.  They almost never manage to get the `h' into
the right place, if they get it at all.  That's why I have developed
the habit to spell my name out whenever people try writing it down.)

>> They could set up underground algae farms to remove the excess CO2 from
>> the atmosphere (scooping off with spacecraft seems less likely).  The algae
>> could receive the light they need either through orbital mirrors which
>> reflect sunlight down volcanic shafts, or lamps powered by geothermy,
>> catalytic fusion, or whatever.  The usual terraforming stuff.
>
>I dunno. It would have to be pretty huge. I was thinking of maybe some way
>to inject chemicals useful to plankton into the oceans so that more could
>produce. 

Nonsense.  This means feeding *zoo*plankton, which then reproduces and
produces even more CO2!  Forget it!

BTW: That underground algae farm thing reminds me at those ancient
underground oxygen tanks on Mars in _Total Recall_.

>       You'd think that more would produce in warm waters, however, I
>guess that the warm water layer somehow prevents nutrients from reaching
>the plankton from the sea floors (just reading an old article on the
>topic). Makes me wonder if the drop of in plankton that I've heard rumors
>about (can you confirm or deny?) is related to global warming and the CO2
>surplus. If so, that would be pretty awful.  Talk about runaway greenhouse.

I think the warming kills off phytoplankton (green algae which
assimilate CO2) but increases zooplankton (small animals which
*produce* CO2).

>Oh, by the way, the computers here will be going down on the 24th and 25th
>due to lack of air conditioning, so if my mail bounces during those days,
>that's why.

Good to know!

>Also, here's the most recent version of that planetary classification
>scheme... final call for comments.
>
>   Solar Companion: Not technically a world but not the main star
>      or even a part of the close-binary pair.

OK.  It might be useful to note that close binaries don't contain planets.

>   Gas Giant: Fairly obvious. Great for wilderness refueling if
>      we're using hydrogen to get around.

One might want to distinguish between Jupiter-type (large, low
abundance of methane, metallic hydrogen mantle), and Uranus-type
(smaller, higher abundance of methane, icy mantle), but this is a
rather minor distinction.

>   Greenhouse: A world gone to hell because of too much
>      greenhouse gases (ala Venus).

OK.

>   Planetoid: Generally a very small world which is not part of
>      an asteroid belt. Not necessarily round. Could be a
>      captured planet. No atmosphere. Composed primarily of rock.

OK, but see my comment on Asteroid (below).

>   Belch Ball: Lifeless terrestrial planet with a poisonous
>      (possibly even corrosive) atmosphere.

Funny name!

>   Primordial: A very young world. Atmosphere varies.
>      Geologically instable. Lots of volcanos and magma seas.

The atmosphere is usually reducing, being composed primally of
nitrogen and CO2, with variable amounts of H2O, NH3, CH4, CO and H2S.

>   Desert World: Generally a non-breathable atmosphere, but there
>      may be water and oxygen tied up as ice crystals in the
>      soil. May be volcanically active. Probably on its way to
>      becoming a shallow world.

OK.  Only the water will be present as ice (unless the world is VERY
cold), but oxygen might be tied up in oxidizing compounds (such as
ferric oxide or nitrates).

>   Exotic: Not an atmosphere you want to breath, maybe because it
>      contains poisonous gases or even lethal micro-organisms,
>      but not a place you can't otherwise walk around, so long as
>      you have your own oxygen supply. Note that an alien
>      ecosystem may well be thriving. Many alien homeworlds will
>      be exotics.

OK.

>   Magma Ball: Ouch, this place is hot. This planet is either
>      very close to the primary or is on its way to becoming a
>      primordial world.

OK.

>   Vacuum Ball: Like the moon, essentially. Lots of rock. No
>      atmosphere. Too big to be called a planetoid.

OK.

>   Shallow World: Has atmosphere but not enough to breath, at
>      least not without descending to a very deep altitude. Mars
>      could be an example.

OK.

>   Dead World: The place is certainly colonizable, but for one
>      reason or another, life either never existed or went
>      extinct in the recent past. Perhaps the sun flared and
>      knocked out the entire ecosystem, or maybe a slew of
>      meteors struck, churning up enough dust that the sun was
>      blotted out for several decades. Almost certainly, the
>      atmosphere is not breathable. In any case, the world is
>      either slowly freezing or heating up and becoming a
>      greenhouse.

Yes. As soon as life is wiped out on a Garden World, the atmosphere
becomes unstable, and will be rendered unbreathable within a few
hundred years.

>   Garden World: Earth is a prime example. Not only can you
>      breath the atmosphere without mechanical aid, but life,
>      either native or transplanted, thrives in abundance.

OK.  Good term!

>   Water World: Over 90% covered by water and ice. Possibly a
>      breathable atmosphere. Possibly a teaming native ecosystem
>      which got evolutionarily stuck due to the total lack of any
>      freestanding continents.

I think it is sensible to distinguish between water worlds with a
breathable atmosphere and those with an unbreathable atmosphere.

>   Liquid World: Surface predominantly covered by ammonia or
>      liquid methane. May contain an alien ecosystem.

The two liquids are different enough to warrant breaking up this one
into two classes.  Liquid ammonia worlds are quite likely to contain
an alien ecosystem (ammonia has similar molecular properties to
water), while liquid methane worlds are less so (methane has far less
similar properties).

Other liquids are probably too exotic to warrant a separate class.
After all, things like that are what `Unusual' is for.

>   Ice Planet: May have a breathable atmosphere so long as there
>      is the ecosystem to support it. More likely a dead planet
>      without a breathable atmosphere.

Yes.  Ice planets with breathable atmosphere (like Hoth[TM]) are
probably very rare, and they are only a few degrees below 0 degs C.
Most breathable-atmosphere ice planets are probably former garden
worlds which have run into trouble, and won't stay habitable for long.

>   Ice Pebble: Like a planetoid, but composed primarily of ice.
>      Usually found only beyond the star's biozone.

OK.

>   Asteroid: Like a planetoid, only part of an asteroid belt.

I think the difference between within/outside a belt does not matter
so much.  After all, an asteroid belt is nowhere near a stone cloud
with chunks only a few hundred meters apart.

>   Unusual: This world cannot be placed in any of the previously
>      defined categories. It may be an artificial planet or
>      perhaps a fluke of nature. GM's discretion advised.

Yes, one always needs a catch-all category for those which fit
nowhere.

BTW: Do you have a web page?


From: james vassilakos <jimv>
Subject: Re: more questions
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Fri, 1 Sep 1995 10:48:41 -0700 (PDT)
 
> I think the warming kills off phytoplankton (green algae which
> assimilate CO2) but increases zooplankton (small animals which
> *produce* CO2).

This would be interesting to get more info on. If it's true, it
points toward a runaway greenhouse effect.
 
> >   Solar Companion: Not technically a world but not the main star
> >      or even a part of the close-binary pair.
> OK.  It might be useful to note that close binaries don't contain planets.

Hmm... this is news to me. Both GURPS and 2300 allow for binary systems
with planets. The only restriction in 2300 is the *3&/3 rule (in order
for a planetary orbit to be stabile, it's orbital radius must be more
than three times or less than one-third the distance between the two
stars.

I was planning on allowing most secondaries to fall within the 1st
planetary orbit, with most of the rest being distant binaries (the
secondary is far enough away that it is effectively a separate
star system). The only problem would be with the medium-ranged
binaries, where the secondary orbits in the same range as planetary
orbits. I was planning on just using the *3&/3 or something
similar for these systems.

> >   Asteroid: Like a planetoid, only part of an asteroid belt.
> 
> I think the difference between within/outside a belt does not matter
> so much.  After all, an asteroid belt is nowhere near a stone cloud
> with chunks only a few hundred meters apart.

True, however, I wanted to make the distinction just so the GM would
know if a belt is present, or if the worldlet is a chunk all by its
lonesome.
 
> BTW: Do you have a web page?

No. Never put the time into. I should probably do one though.


Date: Tue, 12 Sep 1995 14:40:45 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: sf-rpg: planet generation

>Date: Fri, 1 Sep 1995 10:48:41 -0700 (PDT)
>> I think the warming kills off phytoplankton (green algae which
>> assimilate CO2) but increases zooplankton (small animals which
>> *produce* CO2).
>
>This would be interesting to get more info on. If it's true, it
>points toward a runaway greenhouse effect.

I am not sure about the effects on plankton.  It has also been stated that
the increase in CO2 leads to an increase in the growth of
phytoplankton and other plants.
 
>> >   Solar Companion: Not technically a world but not the main star
>> >      or even a part of the close-binary pair.
>> OK.  It might be useful to note that close binaries don't contain planets.
>
>Hmm... this is news to me. Both GURPS and 2300 allow for binary systems
>with planets. The only restriction in 2300 is the *3&/3 rule (in order
>for a planetary orbit to be stabile, it's orbital radius must be more
>than three times or less than one-third the distance between the two
>stars.

That rule only considers the effects of stellar tides on a planet
which is already there.  However, tidal forces which are to weak to
throw a planet out of orbit can be strong enough to disturb the
formation of a planet.  Look at the asteroid belt.  The reason why
there is no planet there is Jupiter's gravity.  If there was a planet
there, its orbit would be stable, but it couldn't form.  Now guess
what a stellar companion with at least 100 times Jupiter's mass can do!

>I was planning on allowing most secondaries to fall within the 1st
>planetary orbit, with most of the rest being distant binaries (the
>secondary is far enough away that it is effectively a separate
>star system). The only problem would be with the medium-ranged
>binaries, where the secondary orbits in the same range as planetary
>orbits. I was planning on just using the *3&/3 or something
>similar for these systems.

See my argumentation above.

>> >   Asteroid: Like a planetoid, only part of an asteroid belt.
>> 
>> I think the difference between within/outside a belt does not matter
>> so much.  After all, an asteroid belt is nowhere near a stone cloud
>> with chunks only a few hundred meters apart.
>
>True, however, I wanted to make the distinction just so the GM would
>know if a belt is present, or if the worldlet is a chunk all by its
>lonesome.

I see.

>> BTW: Do you have a web page?
>
>No. Never put the time into. I should probably do one though.

Do it!

>Date: Fri, 1 Sep 1995 19:33:35 -0700 (PDT)
>Okay, here's what I've got so far...
>                   Contact  Inner  Biozone  Outer
>Gas Giant             -       1       2       3

I'd rather say:
 Gas Giant             -       -       1       3

>Snow Ball             -       -       1       3
>Ice Planet            -       -       1       3

Snow balls and ice planets don't form within the biozone because it is
too warm to allow ice to condense.  (Water ice does not condense in
vacuum above -100 degrees C.)  My bet is:

 Snow Ball             -       -       -       2
 Ice Planet            -       -       -       2

>Zones: Inner, Biozone, and Outer orbital zones are pretty self-
>explanitory. The contact zone is that which actually makes
>contact with the stellar material but is still outside the
>vaporization radius (this zone can only occur in red giants and
>some orange supergiants).

I think there will be no planets in the contact zone because friction
against stellar matter will brake the planets out of their orbits over
the course of a few million years.

>Factors of Planet Type: So far, according to this system, the
>only influencing factor of what sort of planet you end up with in
>a given orbit is the planet's orbital zone. Granted, O, B, and A
>stars aren't supposed to produce planets due to their ridiculous
>level of luminosity (and as corroborated by their high angular
>momentum), however, we only have a few type A stars in the near-
>star data we're working with, and I think they are all of the
>smallest type, so I may overlook this consideration.

MV stars (and small KV stars) have another problem: tidal friction
will slow down the rotation of any biozone planet to the point that
the planet is tidally locked.  Such a world probably cannot maintain a
substantial stable atmosphere.

>Explanation of Shares: Under this system, the program will first
>determine the orbital zone of the world it is generating, then it
>will go to the chart above, map out a probability spectrum, roll
>the dice, and see which world type gets chosen. So for an outer
>zone orbit, there is only a 3/23 chance of a gas giant being
>chosen (this may seem low to you, I dunno).

I think gas giants are more likely than the other types combined
(except as moons).

<list of planet types deleted>
 
Good!

>Date: Sat, 2 Sep 1995 15:58:33 -0700 (PDT)
>BII:   0.5% /  0.0% chance of 4 to 19 planets
>BIII:  0.5% /  0.0% chance of 4 to 19 planets
>BIV:   0.5% /  0.0% chance of 4 to 19 planets
>BV:    1.9% /  0.0% chance of 3 to 18 planets

The GURPS Space charts are quite far away from perfection!  (Yes, SJG
puts out lots of very good stuff, but even they sometimes blow things.
Look at GURPS Aliens, for an example of a truly goofed GURPS book.)

Given that B giants have been OV stars one, where should they have
obtained their planets from?  (BTW: There are no BIII, and BIV stars.)

>AIa:   0.5% /  0.0% chance of 6 to 21 planets
>AIb:   0.5% /  0.0% chance of 5 to 20 planets
>AII:   0.5% /  0.0% chance of 5 to 20 planets
>AIII:  0.5% /  0.0% chance of 4 to 19 planets
>AIV:   1.9% /  0.0% chance of 3 to 18 planets
>AV:    4.6% /  0.5% chance of 2 to 17 planets

AIV does not exist; AIa and AIb supergiants evolve from OV stars and
therefore don't have planets.

>FIa:   1.9% /  0.0% chance of 6 to 21 planets
>FIb:   1.9% /  0.0% chance of 5 to 20 planets
>FII:   1.9% /  0.0% chance of 4 to 19 planets
>FIII:  1.9% /  0.0% chance of 3 to 18 planets
>FIV:   9.3% /  1.9% chance of 3 to 18 planets
>FV:   83.8% / 62.5% chance of 2 to 17 planets

I think that's OK, except that chances are much lower in binary
systems (0.0 for FIV, at most 5% for FV).

>GIa:   9.3% /  1.9% chance of 6 to 21 planets
>GIb:   9.3% /  1.9% chance of 5 to 20 planets
>GII:   9.3% /  1.9% chance of 4 to 19 planets
>GIII:  9.3% /  1.9% chance of 3 to 18 planets
>GIV:  16.2% /  4.6% chance of 2 to 17 planets
>GV:   98.1% / 90.7% chance of 1 to 16 planets
>GVI:  98.1% / 90.7% chance of 3 to 13 planets

I'd reduce chances for GI, GII and GIII.  Again, much lower chances
in case of binaries.  GVI stars have no planets (they are Population II).

>KIa:  50.0% / 25.9% chance of 5 to 20 planets
>KIb:  98.1% / 90.7% chance of 5 to 20 planets
>KII:  98.1% / 90.7% chance of 4 to 19 planets
>KIII: 98.1% / 90.7% chance of 3 to 18 planets
>KIV:  98.1% / 90.7% chance of 2 to 17 planets
>KV:   98.1% / 90.7% chance of 1 to 16 planets
>KVI:  98.1% / 90.7% chance of 3 to 13 planets

Same as for G: KVI don't have planets; lower chances for KIa, KIb, KII
and KIII.  Perhaps:

KIa:   1.9% /  0.0%
KIb:   1.9% /  0.0%
KII:   9.3% /  0.0%
KIII: 16.2% /  0.5%
KIV:  83.8% /  1.9%
KV:   98.1% /  9.3%
KVI:   0.0% /  0.0%

>MIa:  98.1% / 90.7% chance of 3 to 18 planets
>MIb:  98.1% / 90.7% chance of 3 to 18 planets
>MII:  98.1% / 90.7% chance of 3 to 18 planets
>MIII: 98.1% / 90.7% chance of 3 to 18 planets
>MV:   98.1% / 90.7% chance of 1 to 16 planets
>MVI:  98.1% / 90.7% chance of 4 to 14 planets

I'd apply similar changes as suggested for K.  (Again, 0.0/0.0 for MVI.)

Summary: OK for single main-sequence stars, but too high for most
non-main sequence types and binary systems.

I'll have to rework the tables in GURPS Space... as soon as I have
come up with a satisfactory version, I'll send it to you (and put it
on the web)!


From: james vassilakos <jimv>
Subject: Re: sf-rpg: planet generation
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Wed, 13 Sep 1995 09:53:58 -0700 (PDT)
 
> >Hmm... this is news to me. Both GURPS and 2300 allow for binary systems
> >with planets. The only restriction in 2300 is the *3&/3 rule (in order
> >for a planetary orbit to be stabile, it's orbital radius must be more
> >than three times or less than one-third the distance between the two
> >stars.
> 
> That rule only considers the effects of stellar tides on a planet
> which is already there.  However, tidal forces which are to weak to
> throw a planet out of orbit can be strong enough to disturb the
> formation of a planet.  Look at the asteroid belt.  The reason why

Still, I'm picturing the case where, say, the secondary is orbiting
the primary at under .5 AU, and you've got this planet trying to
form at something like 10 AU or more. Or, alternately, you've got
a reverse situation. In any case, it seems to me that there must
be a point there the gravitational influence is overcome by sheer
distance. Maybe the *3&/3 rule is too lenient. What about a *5&/5
rule or a *10&/10 rule or even a *20&/20 rule? Roughly speaking,
there must be some place to draw the line.

> I'd rather say:
>  Gas Giant             -       -       1       3

GURPS allows for the possibility of a large or huge gas giant
to inhabit the inner system, particularly the brown/gray dwarves
(with their metallic hydrogen cores?). Do you think there is
no (or almost no) possibility of this?

> I think there will be no planets in the contact zone because friction
> against stellar matter will brake the planets out of their orbits over
> the course of a few million years.

I'll modify the chart to reflect that there's a low chance of
a planet inhabiting the contact zone.
 
> MV stars (and small KV stars) have another problem: tidal friction
> will slow down the rotation of any biozone planet to the point that
> the planet is tidally locked.  Such a world probably cannot maintain a
> substantial stable atmosphere.

This is fairly serious. Most of the stars in the local area are MVs.
Most of the rest are KVs. If none of these stars can have habitable
worlds due to tidal-locking in the biozone, then we're looking at
an awful lot of lifeless/inhospitable starsystems. Are you quite
sure that all MV-biozone planets will be locked-up in this manner,
and what percentage would you put on KV-bios, MVI-bios, KVI-bios,
and GVI-bios?
 
> GVI stars have no planets (they are Population II).
> KVI don't have planets
> Again, 0.0/0.0 for MVI.

Okay, this is extremely critical. In GURPS, they say that only
about 1% of stars in the galactic disk (which I assume is where
Sol is located) belong to the 1st generation (Pop II) group.
They go on to say that 1st generation stars are very popular in
the core and the galactic halo (this is all from the margin of
page 101 in GURPS:Space). Now, it doesn't say anything about all
subdwarves being 1st generation. Certainly, not all of them could
be. Some would probably be 1st and others would be formed from
the ashes of earlier stars of a less long-lived class. So what
do you think the odds are respectively for GVI, KVI, MVI, KV,
and MV stars being 1st generation?


From: james vassilakos <jimv>
Subject: Re: sf-rpg: planet generation
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Wed, 13 Sep 1995 13:15:32 -0700 (PDT)
 
> I think there will be no planets in the contact zone because friction
> against stellar matter will brake the planets out of their orbits over
> the course of a few million years.

Just had a quick thought. How long does a star stay in the red giant
or orange supergiant stage before blowing its twinkies? If the answer
is just a few million years, then contact zone magmaballs may outlast
the brakes.


Date: Thu, 14 Sep 1995 11:36:52 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu
Subject: Re: sf-rpg: planet generation

You wrote:
>Still, I'm picturing the case where, say, the secondary is orbiting
>the primary at under .5 AU, and you've got this planet trying to
>form at something like 10 AU or more. 

I don't think close binaries will ever have planets orbiting both stars
(except captured ones, which ought to be extremely unlikely).

>	Or, alternately, you've got
>a reverse situation. In any case, it seems to me that there must
>be a point there the gravitational influence is overcome by sheer
>distance. Maybe the *3&/3 rule is too lenient. What about a *5&/5
>rule or a *10&/10 rule or even a *20&/20 rule? Roughly speaking,
>there must be some place to draw the line.

It depends on the mass of the companion.  With a small red dwarf,
*10&/10 might be realistic; with a sun-sized companion, it would be
rather something like *100&/100, I guess.

>GURPS allows for the possibility of a large or huge gas giant
>to inhabit the inner system, particularly the brown/gray dwarves
>(with their metallic hydrogen cores?). Do you think there is
>no (or almost no) possibility of this?

There are binary stars where both stars orbit very closely.  But
binary stars are not just stars with a planet big enough to ignite.
Most binary systems have eccentric orbits, and the few known brown
dwarfs also have.  This means that brown dwarfs are not huge planets,
but tiny stars.

Gas giants in the inner zone are so unlikely that they should not be
placed randomly!

Most current theories even doubt the possibility of gas giants in the
biozone!  The reason is that a gas giant needs a big solid `seed'.  In
the outer zone, water ice is available as building material, which
allows for BIG chunks.  In the biozone, it is not, hence the `seed'
would have to be a huge chunk of rock of at least 20 times Earth's
mass.  (Note that the `seed' must be bigger the closer to the sun,
because the heat makes it harder to catch hydrogen.  Mini-giants such
as Uranus and Neptune therefore only occur in the outer fringes.)

Simulations of solar system evolution most often yield something
resembling our solar system: three to six terrestrials in the inner
and biozone, and two to five gas giants in the outer zone, and usually
an asteroid belt between the outermost terrestrial and the innermost
gas giant.

>> MV stars (and small KV stars) have another problem: tidal friction
>> will slow down the rotation of any biozone planet to the point that
>> the planet is tidally locked.  Such a world probably cannot maintain a
>> substantial stable atmosphere.
>
>This is fairly serious. Most of the stars in the local area are MVs.
>Most of the rest are KVs. If none of these stars can have habitable
>worlds due to tidal-locking in the biozone, then we're looking at
>an awful lot of lifeless/inhospitable starsystems. Are you quite
>sure that all MV-biozone planets will be locked-up in this manner,
>and what percentage would you put on KV-bios, MVI-bios, KVI-bios,
>and GVI-bios?

As I said, GVI, KVI and MVI stars DON'T HAVE PLANETS.
The lower limit for habitable worlds is at something like 5% solar
luminosity.  That's somewhere in the middle of the KV range.  With
such a star, the biozone extends from about 0.2 to 0.3 AU.  Those KV
stars which are above the limit should have the same percentages as GV
stars.  Those which lie below the limit will have planets in the
biozone (if there are at all) tidally locked.
 
>> GVI stars have no planets (they are Population II).
>> KVI don't have planets
>> Again, 0.0/0.0 for MVI.
>
>Okay, this is extremely critical. In GURPS, they say that only
>about 1% of stars in the galactic disk (which I assume is where
>Sol is located) belong to the 1st generation (Pop II) group.
>They go on to say that 1st generation stars are very popular in
>the core and the galactic halo (this is all from the margin of
>page 101 in GURPS:Space). Now, it doesn't say anything about all
>subdwarves being 1st generation. Certainly, not all of them could
>be. Some would probably be 1st and others would be formed from
>the ashes of earlier stars of a less long-lived class. So what
>do you think the odds are respectively for GVI, KVI, MVI, KV,
>and MV stars being 1st generation?

AFAIK, it is just such that population II (i.e., 1st generation) stars
simply do have a different main sequence, due to their lack of heavy
elements.  V is the main sequence of the later stars, thus GV, KV, and
MV are never 1st generation (unless they are 1st generation stars
crossing the main sequence on their way from their own main sequence
to the giant branch, which are of course VERY rare).  VI is the main
sequence of the 1st generation stars, thus GVI, KVI and MVI are always
1st generation.

>Just had a quick thought. How long does a star stay in the red giant
>or orange supergiant stage before blowing its twinkies? If the answer
>is just a few million years, then contact zone magmaballs may outlast
>the brakes.

It is a few million years, with supergiants (which evolve from big,
planetless stars anyway) less than that.  Thus, there might be a
planet in the contact zone, but not for long.  Chances are perhaps a
few per cent.


From: james vassilakos <jimv>
Subject: Re: sf-rpg: planet generation
To: rhiemeir@ibr.cs.tu-bs.de (Joerg Rhiemeier)
Date: Thu, 14 Sep 1995 15:58:25 -0700 (PDT)
 
> As I said, GVI, KVI and MVI stars DON'T HAVE PLANETS.
> AFAIK, it is just such that population II (i.e., 1st generation) stars
> simply do have a different main sequence, due to their lack of heavy
> elements.  V is the main sequence of the later stars, thus GV, KV, and
> MV are never 1st generation (unless they are 1st generation stars
> crossing the main sequence on their way from their own main sequence
> to the giant branch, which are of course VERY rare).  VI is the main
> sequence of the 1st generation stars, thus GVI, KVI and MVI are always
> 1st generation.

So what you are telling me is that ~100% of Population II stars are
Class VI and vice-versa, so that 100% of VIs are Pop II. Taking a sample
of stars around Sol, I see that approximately 5% are Class VI, however,
according to GURPS:Space, only about 1% of the stars in this region of
space are supposed to be Population II. So, in short, you're telling
me the authors screwed up. I also took at look at some basic astronomy
books at the local library, being that I'm a novice at this. 
Unfortunately, the books I looked at dwelled on the star color but
not on the size, though I didn't see any mention under the sections
describing Population II stars that they are all dwarves (except
for cross-overs, as you say).

I do have a quote here from one of these books which looks somewhat
suspicious. "...population II stars rarely contain blue giants", which
would seem to indicate that sometimes they do. However, the author goes
on to say, "they (population II stars) cannot include blue giants",
which seems somewhat contradictory with his previous statement. However,
if nearly all population II stars in this galaxy are dwarves and nearly
all dwarves in this galaxy are population II, then why didn't the author
just say so?

It would be convenient for me if, in fact, this was the case, however,
I want to be a little more certain about this if I am to run with it.
How certain are you, and can you point me to a source which agrees
with you about this?


Date: Fri, 15 Sep 1995 14:37:05 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: jimv@cs.ucr.edu, nv91-asa@nada.kth.se
Subject: Mails from James Vassilakos, Sep. 14

>BTW, I'm thinking of setting up a mailing list for this group
>just to make these mail-forwarding logistics easier.

Good!  Do that!

>Date: Mon, 11 Sep 1995 17:03:33 -0800
>To: jimv@cs.UCR.EDU (james vassilakos)
>From: llvogel@teleport.com (Laura L. and Allan Hayes Vogel)
>Subject: Planetary possibilities
>
>I don't think your source who claimed "that the M stars which are long
>lived are probably going to be 1st generation (Population II, very old) and
>hence not likely to have anything but lots of hydrogen and maybe the
>occasionaly captured planetoid" is correct. As I understand it, the initial
>mass of the protostar has more to do with the observed stellar class, but
>stellar evolution isn't my speciality. Furthermore, there's been a claim
>that Barnard's Star, an M5 star about 6 lights out from Earth, has two
>superjovians/brown dwarves in orbit around it, one with a mass of 10
>Jupiters. Although this report has not been confirmed to my knowledge (and
>I may be a bit dated here), but if it's correct, that would disprove your
>source.

M stars CAN be very old, but they needn't to.

I even think that 1st-generation stars don't have planets at all --
not even pure-hydrogen giants.  

>The key difference between the pop-1 (2nd and later generation) and pop-2
>(1st generation) stars is that the pop-2 stars only have hydrogen present
>in their systems while the pop-1 stars have heavier elements present.

Exactly.

>From: jimv
>To: Allan Vogel
>It may be the case that the gas giants around Barnard are totally composed
>of hydrogen. They'd probably appear a milky white with no bands of various
>other elements. They'd be entirely uniform because they'd be composed
>solely of hydrogen. This is assuming that Bernard is a 1st generation
>star.

But it might just as well be a younger star.

I also think that 1st generation stars don't have planets at all.  The
gas giants in the solar system condensed around a core of rocks and
ice.  With a 1st generation star, those pure hydrogen planets had to
condense spontaneously out of thin hydrogen gas, which I consider
extremely unlikely, if not impossible (not enough mass for spontaeous
gravity-driven collapse).

>> I've followed this topic for over 25 years as a research scientist
>> interested in the possibility other habitable planets and I think GURPS
>> Space have several errors in their (listed) probabilities of habitable
>> planets. 

Indeed!  Habitable planets of red giants?  Ridiculous!!!

>> Another thing is that it's not an either/or situation of
>> habitability; what about marginal worlds? I'll bet that there's a lot more
>> marginals than perfects out there. (As an aside, now speaking as a
>> professional ecologist instead of a gamer, the opportunities for confirming
>> many of our hypotheses about the environmental and evolutionary processes
>> would be tremendous if we had _even just one_ more planetary biosphere,
>> even a marginal world's biosphere, to measure, study, and compare with
>> Earth - Man, would I love to have the chance to study it!!).
>
>Agreed. It's too bad we don't have more to go on. However, at least this
>presents lots of opportunity for speculation.

And speculation is all we can do!

>Date: Wed, 13 Sep 1995 23:57:04 -0800
>To: james vassilakos <jimv@cs.UCR.edu>
>From: llvogel@teleport.com (Laura L. and Allan Hayes Vogel)
>First, I'd drop everything above an A5 and all Size I and II's because, as
>you noted later in your e-mail, no planets are likely orbitting the
>brighter classes. Nor are giants [and white dwarves] likely to have
>planets. 

At least no habitable ones.  They are also very old anyway, with
not much of heavy elements to start with.

>Second, I'd add individual subclasses between A5 and K5 at every
>half class interval; the increase isn't excessive if you've dropped the
>brighter classes.

An important line is to be drawn at F5 stars 3 times brighter than the
Sun.  These stars have a lifetime of about 3000 million years, which
is a good estimate for the minimum for having habitable planets.

>>I'd be interested in seeing it (- my planetary parameters program).
>Okay, I'll e-mail a copy to you when I'm finished.

Which language is it written in, and for which system?

>>   Magma Ball: Ouch, this place is hot. This planet is either
>>      very close to the primary or is on its way to becoming a
>>      primordial world. It is possible that such a world is
>>      tidally locked to its sun. Then, one half would be a
>>      sea of lava, and the other half would be frozen.
>
>Mercury, I presume? (said Stanley) A low probability planet, I suspect;
>your odds (i.e., shares of likelihood) aren't bad for this group.

Well, Mercury is just a standard-issue vacuum ball.  It is very hot
during the day, but there are no lava seas there.

>>   Primordial: A very young world. Atmosphere poisonous (usually
>>      reducing, being composed primally of nitrogen and carbon
>>      dioxide with variable amounts of water vapor, ammonia,
>>      methane, carbon monoxide and hydrogen sulfide).
>>      Geologically instable. Lots of volcanos and magma seas.
>
>Very low probability as most worlds have already passed through this stage
>a long time ago (>4 *10^9 years ago for Earth in a 4.5*10^9 year long
>history); I'd downgrade the number of shares to _much_ less than one in the
>biozone - about1/10.

The probability depends on the star!  If it is an A-type star, most
planets in the biozone are primordial, because the star doesn't live
much longer!

And then there is quite a longe rang of intermediates between
primordial and garden worlds.  Earth was Primordial until about
perhaps 3000 million years ago, but became a garden world not before
about 600 million years ago.  Most of the range in between could be
lumped into Belch Ball and Marginal (though the definitions given
don't include them), but I'd suggest another category (perhaps
`Unripe') for that.

>Parallel to these classes, I would include a superterrestrial class, a
>rocky, high-density-core world with a planetary mass between 2 and 10 times
>Earth and an extremely thick atmosphere with a share of one in the biozone.
>Of course, my ex-college roommate, G. David Nordley, may be correct in his
>Analog article of last year that such don't exist, but the fellows that
>publish in Icarus seem to like the idea still, so I'd keep it until Gerry
>can prove them wrong.

We have no known example of such a big terrestrial world, and many
simulation runs seem to indicate that they don't exist.  I think the
matter is still unsettled.

>>   Marginal World: Complex lifeforms either never evolved on this
>>      planet or went extinct sometime within the past couple
>>      million years. Perhaps the sun flared and knocked out the
>>      entire ecosystem, or maybe a slew of meteors struck,
>>      churning up enough dust that the sun was blotted out for
>>      several decades. Irregardless, this world is ripe for
>>      colonization. Some terraforming will be required, however,
>>      if the world is to remain habitable over the long term.
>>      Mars might have been a good example eons ago.
>
>I think that you may be lumping too much possibilities together here
>although your category makes perfect sense. Some may never be good
>colonization targets however.
>
>I would also include in this group optically-reversed-protein worlds,

Optically reversed proteins are only one of the worst cases of
bio-incompatibility.  No two worlds will have exactly the same
biomolecules.  Some basic compunds (such as most amino acids) will be
found virtually anywhere, but of the more specialized molecules (such
as most vitamins -- extreme case: B12) at least some will be missing!
Alien life may be inert or poisonous to us.  In the latter case, soil
and water, perhaps even the atmosphere may be polluted!  This means
that there is a continuum of possibilites between a perfect garden
world and an archetypical belchball.

>	moist
>(as opposed to runaway a la Venus) greenhouse worlds, and heavy metal
>worlds (i.e. worlds with too high concentrations of heavy metals for
>terrestrial organisms, although the native biota has evolved tolerances
>(and possibly even requirements) for large amounts of heavy metals as other
>possibilities. (And lest you think that my last example is crazy or only a
>minor possibility, first, heavy metals are one of my research specialities
>as an ecologist - I did both my M.S. and Ph.D. on this subject, and second,
>there was a so-so SF novella published about 30 years ago in either IF or
>Worlds of Tomorrow - the sibling publications of the late [and mourned]
>Galaxy magazine - using this very idea as its theme.)

For a GOOD example of a heavy metal world, see _Startide Rising_ by
David Brin.

>>   Desert World: This world isn't entirely desert, but the
>>      hydrographic percentage is relatively low. Most likely, the
>>      atmosphere is somewhat thin, and the change in temperature
>>      from day to night is fairly extreme. Assuming an ecosystem
>>      is present, however, the atmosphere is probably breathable.
>
>Last point is very doubtful if the percent land over 90%. (I call anything
>over 45% land a desert world as the percentage of desert gets too high for
>good oxygen generation - see note below.)

Possible.

>>   Water World: Over 90% covered by water and ice. Probably a
>>      breathable atmosphere. Possibly a teaming native ecosystem
>>      which got evolutionarily stuck due to the total lack of any
>>      freestanding continents.
>
>Ja, only I use 80% in my program, and I'm not sure about the breathability
>- see note below.

The formulae below give 0.15 for a 100% water world, which is a bit
less than half the value for Earth; i.e. marginally breathable.

>BREATHABILITY PROBLEMS,
>I have attempted to model this variability in my program, using a
>biogeochemical text of mine as my data source. I combined all non-desert
>biomes into one. The resulting mean productivity was just under 1.0 (0.98)
>as mm Hg of oxygen produced per one million square kilometers. For all
>oceanic biomes, the resulting value is 0.15, and the value for terrestrial
>deserts is 0.034. A good first order estimate for the amount of desert on
>an inhabitable world is the square of the percent land. 

Makes sense.  Small islands usually don't have much desert, but huge
super-continents usually have a desert core.

>	If you take the
>surface area of your planet relative to Earth and multiply by 510, then
>multiply it by the following term for the effectiveness of oxygen
>production, you should get a quick estimate of the amount of oxygen
>available to breathe in mm Hg.
>
>Relative effectiveness of oxygen production =
>        %ocean * 0.15 + % land^2 * 0.034 + (1 - % ocean - % land^2) * 0.98
>
>[I call the last term, 1 - % ocean - % land^2, the % fertile land, because
>it's doing most of the oxygen generation.]
>(The earth standard value for this term is 0.312; you can probably
>normalize it fairly easily.)

I have done some quick calculations, and come up with these results
(assuming that Earth has 21.5% -- I don't know the exact value):

Water%  Oxygen% (based on Earth standard surface pressure)
---------------
    0      2.3
   10      9.0
   20     14.4
   30     18.4
   40     21.2
   50     22.6
   60     22.8
   70     21.6
   80     19.2
   90     15.5
  100     10.4

This means that with about 30 to 80% water, the oxygen percentage does
not differ significantly from Earth.

>>   Belch Ball: Lifeless terrestrial planet with a poisonous,
>>      toxic, or possibly even borderline-corrosive atmosphere.
>
>Chlorine, anyone? Of course, out of the biozone, it should be methane and
>ammonia.

I don't think chlorine atmospheres are very likely.  Chlorine must be
produced by life forms, similar to oxygen; however, oxygen is the more
likely alternative as there will always be more H2O than HCl or Cl-.

>>   Greenhouse: A world gone to hell because of too much
>>      greenhouse gases (ala Venus).
>
>Correction, greenhouse worlds are terrestrial planets which are too close
>to their primary. Earth has the same amount of carbonates proportional to
>its mass as Venus has in carbon dioxide. Venus just got cooked is all (it's
>really too bad that Venus and Mars weren't switched; "Minerva" [as it's
>known to some of us in biogeochemical circles] would have been another
>inhabitable world - not breathable, but easily inhabitable.) Anything with
>an E > 1.5 ought to get cooked, so become a greenhouse world. 

What is `Minerva', and what does E stand for?

>I recommend
>dropping the greenhouse shares in habitable zone to zero (if there's a
>greenhouse world in the habitable zone, it's clearly a specific, and
>artifically-caused, situation, i.e., an example of your special category)

You mean: a run-down, polluted ecosystem gone haywire?

>>   Exotic World: This planet has life, but not as we know it.
>>      The atmosphere is poisonous to humans and may even contain
>>      lethal micro-organisms. The temperature, however, is
>>      probably moderate enough that an individual can walk around
>>      unscathed by the environment so long as he has a self-
>>      contained oxygen supply. Many alien homeworlds will
>>      be exotics.
>
>Nice idea!

And quite likely to be encountered, too.

>From jimv@cs.UCR.edu Fri Sep 15 00:57:08 1995
>So what you are telling me is that ~100% of Population II stars are
>Class VI and that 100% of VIs are Pop II. 

There are also Pop.II giants (only small ones: MIII, KIV, MIV), but
most Pop.II stars are class VI subdwarfs.

>Taking a sample
>of stars around Sol, I see that approximately 5% are Class VI, however,
>according to GURPS:Space, only about 1% of the stars in this region of
>space are supposed to be Population II. So, in short, you're telling
>me the authors screwed up. I also took at look at some basic astronomy
>books at the local library, being that I'm a novice at this. 
>Unfortunately, the books I looked at dwelled on the star color but
>not on the size, though I didn't see any mention under the sections
>describing Population II stars that they are all dwarves (except
>for cross-overs, as you say).

If 5% stars are class VI and 1% Population II, at least one of the
figures is wrong!  A class VI subdwarf is simply not part of a
Population I star's lifepath!  And I have seen a list in at least two
books of which objects fall in which population, and it listed
`subdwarfs' in Population II.  The list split P.I into extreme, older
and disc population and P.I in intermediate and halo population.  If I
remember correctly, it was like this:

Extreme (younger than 1000 Myr):
supergiants, O and B stars

Older (between 1000 and 3000 Myr):
bright giants, cepheids, A stars

Disc (between 3000 and 7000 Myr):
normal giants, sun-like stars [and therefore habitable worlds]

Intermediate (between 7000 and 10000 Myr):
[don't remember, not much anyway]

Halo (older than 10000 Myr):
stars in globular clusters, subdwarfs

The extreme and (to a lesser extent) older populations are
concentrated in the spiral arms, while the disc population is evenly
distributed over the galactic disc.  This means that habitable worlds
are not more frequent in the spiral arms than in the gaps between!

>I do have a quote here from one of these books which looks somewhat
>suspicious. "...population II stars rarely contain blue giants", which
>would seem to indicate that sometimes they do. However, the author goes
>on to say, "they (population II stars) cannot include blue giants",
>which seems somewhat contradictory with his previous statement. However,
>if nearly all population II stars in this galaxy are dwarves and nearly
>all dwarves in this galaxy are population II, then why didn't the author
>just say so?

It's confusing what he wrote.  I guess he just wasn't sure.  Perhaps
he was also referring to the `blue straggler' mystery: some globular
clusters contain A and even B stars, though this contradicts our
theories about stellar evolution.

>It would be convenient for me if, in fact, this was the case, however,
>I want to be a little more certain about this if I am to run with it.
>How certain are you, and can you point me to a source which agrees
>with you about this?

I am not too certain about it, and I unfortunately cannot state a
source in English.  

And anyway: no-one has ever seen the same star be born and die, hence
most what we know about stellar evolution is conjecture, anyway.


Date: Mon, 18 Sep 1995 16:11:44 +0200
From: Joerg Rhiemeier <rhiemeir@ibr.cs.tu-bs.de>
To: nv91-asa@nada.kth.se
Subject: Re: Mails from James..

Hi Anders!

You wrote:
>On Fri, 15 Sep 1995, Joerg Rhiemeier wrote:
>
>> >Also, I see that Joerg carbon-copied you this morning's email which he
>> >sent, so I won't bother forwarding that, however, there is some mail here
>> >from another guy. You and Joerg may be interested in seeing what he had
>> >to say. BTW, I'm thinking of setting up a mailing list for this group
>> >just to make these mail-forwarding logistics easier.
>> 
>> Good!  Do that!
>
>I agree. This is getting too confusing for my poor brain (I'm involved in 
>a similar discussion about another game in parallel to this). 

Let me know about that parallel discussion!

>	By the way 
>Joerg, I *am* responding to your long mail as per August, 

Go on!  I am looking forward to your reply!

>	and just 
>realized that you might have broken off our friendship due to my sins of 
>Netscape - I hope to make amends soon. :-)

I haven't broken off our friendship.  It was a kind of shock therapy,
to prevent you from moving up the wrong path.  To me, fighting
Netscrape enhancements is a serious issue, as any Netscrape page
decreases the chance that HTML 3 catches on.  It is a battle between a
good (HTML3) and a bad (Netscrape) solution for the same problem.

But you haven't removed them yet :-(  It looks like I'll have to come
up with heavier ordnance (maybe telling Germany's biggest conservative
tabloid about http://www.nada.kth.se/~nv91-asa/atomic.html ?) to get
you back on the HTML path :-)

But now, let's come back to the `real' discussion...

>Some brief comments and ideas:
>
>> M stars CAN be very old, but they needn't to.
>
>Are their luminosity similar during their long lifetimes? I think it ought
>to be that, thinking of how blue stars quickly burn their fuel. 

I think the luminosity of a star does only increase slightly over time
during the main sequence stage.

>> I even think that 1st-generation stars don't have planets at all --
>> not even pure-hydrogen giants.  
>
>Not even pure-hydrogen gas-giants?

The problem is that the gas giants in our solar systems formed around
solid cores composed of rock and ice, which condensed out of the solar
cloud.  With a 1st-generation star, there are no heavy elements to
form such a core, thus the cloud has to self-compress through its own
gravity.  And I guess that only stars can form this way, not smaller
objects.

>> I also think that 1st generation stars don't have planets at all.  The
>> gas giants in the solar system condensed around a core of rocks and
>> ice.  With a 1st generation star, those pure hydrogen planets had to
>> condense spontaneously out of thin hydrogen gas, which I consider
>> extremely unlikely, if not impossible (not enough mass for spontaeous
>> gravity-driven collapse).
>
>That would depend on the homogenity of the gas cloud, of course. If the 
>cloud collapse was sufficiently chaotic and uneven, then they might form. 
>But the more I think about them, the more unlikely they begin to seem. 
>Too bad, I really like the idea (wonderful refueling stations!).

Perhaps they might form under suitable conditions, but I guess they
will occur fairly rarely.

>> Indeed!  Habitable planets of red giants?  Ridiculous!!!
>
>You might terraform one, but it won't last. Reminds me of an UFO-logist 
>who claimed the aliens came from the Pleiades, and when confronted with 
>the fact that they were very young stars just responded "But the aliens 
>evolved quickly!". 

Ah yes, these darn stupid UFOlogists!  Lots of faulty logic and
superficial thinking, and often mistaking cause and effect!  They
especially lack a sense for quantities and relations (and they lack
knowledge anyway).  Must of their faulty logic runs as the following
example (which is famous in Germany, where mothers used to tell
children in former times that children are brought by storks):

I. The birth rates in Germany have been decreasing during the last 100
   years.

II. The number of storks observed in Germany has also been sharply
    decreasing during the same time period.

III. Therefore, it is obvious that children are actually brought by storks.

>> An important line is to be drawn at F5 stars 3 times brighter than the
>> Sun.  These stars have a lifetime of about 3000 million years, which
>> is a good estimate for the minimum for having habitable planets.
>
>Why is this? 

When writing `habitable', I was thinking about planets with
human-breathable atmospheres.  And such atmospheres take quite long to
build up.  Minimum for human breathing at Earth pressure is about 10%
oxygen (i.e., half the amount of today), and this wasn't reach on
Earth until about 1000 million years ago.

Life itself pops up much earlier, about as soon as 500 million years
after the star reaches main sequence stage.  But it is a long road
from the first replicators to a garden world.

>> >Parallel to these classes, I would include a superterrestrial class, a
>> >rocky, high-density-core world with a planetary mass between 2 and 10 times
>> >Earth and an extremely thick atmosphere with a share of one in the biozone.
>> >Of course, my ex-college roommate, G. David Nordley, may be correct in his
>> >Analog article of last year that such don't exist, but the fellows that
>> >publish in Icarus seem to like the idea still, so I'd keep it until Gerry
>> >can prove them wrong.
>> 
>> We have no known example of such a big terrestrial world, and many
>> simulation runs seem to indicate that they don't exist.  I think the
>> matter is still unsettled.
>
>Why can't they form? The vicinity of the star might blow away much of 
>what would otherwise have developed into a gas giant, leaving a 
>superterrestrial world. This may depend on how fast the star ignited, of 
>course.

This is possible, of course.  We just don't know how big solid chunks
in the inner and biozone grow.  If gas giants exist in the inner and
biozone, there will also be super-terrestrials, of course.

>Apropos atmospheres, don't forget the problems with high oxygen
>atmospheres: fires. If I don't misremember, at a sufficiently high
>percentage of oxygen in the atmosphere (or rather, sufficiently high
>oxygen partial pressure) even wet plants are combustible, and great fires
>could become a serious problem/bizarre opportunity for land life. I think 
>the figures are mentioned in The Anthropic Cosmological Principle by 
>Barrow and Tipler (great book about just about everything).

I also remember reading something in this vein.  It is estimated that
the limit lies near 25 or 30%.  Actually, the oxygen percentage curve
reconstructed for Earth's atmosphere pretty much looks like a sigmoid
curve where present-day Earth sits at the beginning of the asymptotic
branch, as expected for the case that there is an upper limit.

>> The extreme and (to a lesser extent) older populations are
>> concentrated in the spiral arms, while the disc population is evenly
>> distributed over the galactic disc.  This means that habitable worlds
>> are not more frequent in the spiral arms than in the gaps between!
>
>Is this true? I thought the spiral arms were brighter because there were 
>more *young* stars there! Hmm, someone has been feeding me 
>misinformation... :-)

I admit that the term `older population I' is misleading!  The `older'
refers only to the Extreme P.I, which is even younger.  The `older'
population is still younger than 3000 million years.  (This also means
that all garden worlds fall into the disc population.  The extreme and
older pops are too young, intermediate and halo have too little
amounts of heavy elements.)  Of course, it is the young stars which
make spiral arms shine and glisten!

The stars of the disc population formed within the spiral arms, but
drifted outwards.


