Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!mhuxl!houxm!houxz!vax135!cornell!uw-beaver!tektronix!hplabs!sri-unix!Poskanzer.PA@XEROX.ARPA From: Poskanzer.PA@XEROX.ARPA Newsgroups: net.sf-lovers Subject: Re: constructed worlds Message-ID: <2098@sri-arpa.UUCP> Date: Tue, 17-Jul-84 13:57:43 EDT Article-I.D.: sri-arpa.2098 Posted: Tue Jul 17 13:57:43 1984 Date-Received: Fri, 20-Jul-84 04:00:26 EDT Lines: 27 From: Jef Poskanzer All the constructed worlds messages, though fairly repetitive, missed one very good example: "Moonbow", by J. P. Boyd, a novelette in the May 1981 IASFM. It was not a particularly good story, but the construction was excellent. Imagine a very thin donut about one-fifth as big as the sun. Specifically, it's got a major radius of 150,000 km, minor radius of 1500 km, surface gravity 0.2 Gs, about 1 Barr of air pressure, toroidal spin of 6 km/sec, and 16 times the surface area of Earth. I call this type of object a torusworld. At the time the story came out, I was investigating them on my own, so the story got me pretty excited. One thing I like about torusworlds is that, unlike EVERY other non-trivial constructed world in SF, you can build them with known physical laws and without unreasonably strong materials. Another thing I like is the gravitational dynamics. Boyd's story did not say much about that aspect, but I can tell you they are pretty wild. For example, there is a helical orbit looping through the "hole"... The best technical reference on torusworlds is "Hydrodynamics", by Sir Horace Lamb, first published in 1878. There is also a paper by Laplace, published in 1780, looking into whether the rings of Saturn could be a torusworld. "Plus ca change..." --- Jef