pugh@topaz.ARPA (08/02/85)
From: "pugh jon%b.mfenet"@LLL-MFE.ARPA Gravity has been a fun topic in SF for years, and a thorn in the side of physicists too. Consider this: No one knows how or why gravity works, it just does. Albert says it is because matter warps space, but he still left it as an inherent property of matter. Matter just likes to clump together. This leaves writers a lot of room to wave hands. The only way to create gravity is to gather matter together. There is only one conversion process to transform gravity into another form of energy, and that is going downhill, which converts the gravitational potential into kinetic energy. Even this is not really using gravity, because gravity is defined as just storing the energy used to elevate matter in the first place. Likewise for all forms power generated from gravity, like hydroelectric; they are just manifestations of the energy that was used to raise the medium in the first place. In the case of hydro, the sun evaporates the water which then rises and falls above the dam. There is no use of gravity alone. It requires a medium to work with, i.e. matter. Many SF stories assume some form of gravitic power or locomotion. There is no basis for this in science. No one has a clue how to do anything even remotely associated with this topic. Gravity is just there, and matter is the only thing it affects. Mind you, most everything we have is matter, so that's no small effect, but it is still limited to a single direction (actually it's a vector sum, but no difference). I believe HG Wells was one of the first to use the concept of anti-gravity with his invention of Cavorite. They used it to fall up to the moon. A story rife with scientific inaccuracies, but what do you expect at the turn of the century? Antigravity is the simplest form of being able to control the magnitude and/or direction of the gravity force vector. A gravitic drive would be a more complex manifestation of the same principle. How would it work? If one could change the direction of the gravity vector, then travel near massive bodies becomes a snap. Try changing the gravity vector out in deep space and see what it gets you. Gravity is another of the distance squared drop offs. It fades fast. And we don't know how much is reaching us from the Milky Way, since we can't go anywhere else and measure. It might be that there is a large gravity force throughout the universe, but since everything is orbiting something, it isn't noticable to us. A gravity drive could be useless anywhere away from a massive body. Assume we could create a point source of gravity though. That would be an awesome ability. Virtually any sizable force would be useful (enough to create a pull of over 1/4 g). Create it reletive to a ship and that ship will fall along the path intended. It would be fairly simple to maneuver if the force could be dynamically controlled, otherwise it's a planning problem of when to slow down and where to turn. A powerful one would make a dandy weapon too. Larry Niven had pirates pulling little black holes around with magnets (dump a bunch of ions into a hole and it can get a mighty powerful charge) to nab hyperdrive ships. Imagine if you could create a black hole. Once it got enough matter, you could turn off your machine and it would continue to grow. Once again you would need matter, but this would collect it. Enough power and you might be able to counteract a black hole (where would you get that much power?) by balancing the forces. On a smaller scale, crushing metal would be easy. At any rate, speculation could run on forever. There are, at this time, no answers and a lot of questions. We should all push for more experiments along these lines. Most major experiments have had to be conducted in the confines of the earth's gravity well. Now we are able to escape that, somewhat, with the space shuttle. We need a better understanding of this fundamental force if we to ever unify the field theory, or escape this little ball of dirt we were born on. Jon Pugh pugh%e@lll-mfe.arpa The National Magnetic Fusion Energy Computer Center at the Larwence Livermore National Laboratory in sunny Livermore California
OSTROFF@RUTGERS.ARPA (08/08/85)
From: OSTROFF@RUTGERS.ARPA Since the subject of gravity has recently been brought up (ugh) I remember reading a short story long ago about a truck driver (perhaps he had a scientist friend) who learned to control gravitons. He would overload his truck, and just out of range of the terminal dump all the gravitons so the load wieghed almost nothing and thus made the driving much faster, easier, and less wear on the truck. Shortly before reaching his destination, he would stop under a big concrete railroad bridge to grab some gravitons and up his cargo to approximately the correct weight. Among other problems - after a while he had removed so many gravitons from the bridge that it broke up and floated away. Anyone else remember this? Jack (OSTROFF@RUTGERS.ARPA) -------