From: nickh@CS.CMU.EDU (Nick Haines)
Subject: different kind of universe
Date: Tue, 14 Apr 92 23:19:59 GMT
Organization: School of Computer Science, Carnegie Mellon University
Distribution: rec
Originator: nickh@VOILA.VENARI.CS.CMU.EDU

Well, I figure it's time I gave the rest of you something to think
about instead of trying to answer all your questions.

I've written a few stories set in a universe of my own devising, with
some rather different physical laws. I'd like opinions and ideas on
the physics and sociology.

To start with, gravity doesn't work the way it does here. I'll explain
how it _does_ work below. (I get this out of the way to avoid the
obvious flames). And the universe appears blatantly artificial to us,
but so what (remember the Arch in Ringworld).

The universe is flat three-dimensional, infinite (or possibly
finite/closed/toroidal, but so nearly flat that it appears flat), and
full of breathable air.  It is oriented by a gravitational `force'
(not, I repeat, like our gravity), which is in the same direction
everywhere. This force affects some things (such as people) but not
others (such as air). The key behaviour is that the terminal velocity
of a falling human body in air is about 5 m/s (~11 mph). To give you
some idea, this is the same speed with which you hit the ground if you
jump (or fall) off your desk. Not all objects need fall with the same
speed. The speed is determined by composition, mass, and fudge-factor
:-). In particular, a person carrying much of anything (including
excess body-fat) falls significantly faster (say 50 m/s), although
nothing that falls does so much slower than a person (I haven't needed
to come up with a really good fudge-factor for this yet. I don't need
one for most of my stories (Remember: all my characters have grown up
in this universe.  It just _is_ that way to them).  You're welcome to
provide rationales).

There are a large number of fixed objects in the universe, which do
not move with respect to each other (think of them as infinite
non-gravitating masses if you like). The ones I have dealt with (that
part of my universe in which I have written stories) are all flat
horizontal discs, of sizes varying from tens of metres to thousands of
kilometres, with thickness of a few metres. Light is emitted from the
undersides of some discs, and this brightens/fades on a cycle (not all
discs are in synch). People (/plants/animals/ecologies/societies) live
on the upper sides. They are placed seemingly at random, separated by
some kilometres horizontally (enough for some _really_ elegant
suspension bridges) and some hundreds/thousands of kilometres
vertically. Which is to say, a few days falling (great waterfalls...).
There are enough clouds, and air is opaque enough, that in general you
can't see where you'll end up if you go off the edge. There's a goodly
amount of earth and rock, but much less on the smaller discs---it gets
washed off much faster than it is deposited.

What else about the science? Ah yes, there's weather, of course, some
on a grand scale, not much climate except as created by the discs, and
there are some (not many) really _large_ creatures (up to several
hundred metres) which can ascend slowly. Sort of like Jovian
(/Herbert) gas-balloons, although the mechanism isn't described and
will clearly depend on the rationale I end up choosing for the way
gravity works.  The rest of the ecology is fairly straight-forwardly
what you would expect---some weird creatures, but mostly fitting
typical ecological niches. There are no really big (much larger than,
say, pterosaurs) fast-moving aerial beasties. I can put a fudge-factor
for this into the `gravity' equation. There are good places for really
_extreme_ rainforests (excess precipitation, very warm, and the weight
that trees have to support is much smaller, because of the way gravity
works).

On to societies. Well, the main culture I have written about (having
an infinite universe is nice, coz there's room for lots of cultures
:-) is medium-low technology (ie metals but no electricity), and has a
prevailing belief that the universe was created, by a being they call
Godbelow, who lives AT THE BOTTOM. To progress spiritually, one must
make pilgrimage downwards, by jumping off.  Without much (culturally
this translates to `any') food or equipment (otherwise you fall too
fast...). People who fall from above are clearly less worthy/holy, and
can be treated as such. But might be pilgrims. On very large discs,
subcultures grow up believing themselves to _be_ at the bottom, and
are therefore either atheistic, proud, both, or believing that God is
AT THE TOP (or elsewhere). These are either heretical (ie minorities)
or mainstream.  There are, of course, religious wars. Note that
generally speaking cultures are _vertical_, since it's hard to spread
horizontally. Also, strange cultural things happen _under_ big discs,
where no-one goes unless there was a really big storm. (Some of the
big storms make the Oz tornado look puny).

Oh, and there are some nomadic cultures, using the big balloon
creatures, and some slave cultures, using pilgrims from above, and
some higher-tech cultures near one or two really _strange_ oracular
places, and lots of places where living is difficult (in the
shade---or the too-bright illumination---of a big disc tends to get
you desert one way or another), and some weird mental states, which
can be looked at as communications from Godbelow, or dismissed as
raving (that part's a direct steal from our universe :-),

Last, but not least, there is the Earth. In one story, this gets
zapped into my universe as a new stationary object. And yes, all the
people and all of the water on the `down' side (which happens to
include Europe) fall off. Just my way of introducing a few familiar
people to point out the weirdnesses.

Comments, please, by email or post. Intelligent criticism welcome.
Flames to /dev/null.

Nick Haines nickh@cs.cmu.edu

PS: oh, by the way, I'd appreciate at least being _told_ if anyone
else uses any of these ideas.
Newsgroups: rec.arts.sf.science