From: "Smith, Jeff" <Jeff.Smith@bridge.com> To: "'halo@bungie.org'" <halo@bungie.org> Subject: Tech Theories - Why Halo Theory Doesn't Hold Water Date: Fri, 28 Jul 2000 09:45:11 -0500 While centrifugal (really normal-force) artificial gravity seems like nice theory from a distance, there are subtleties that Bungie shouldn't ignore. Although it has been said that Halo 'defies the law of known physics', it seems a little silly going with the whole 'mega-engineering-feat-of-the-universe-with-artificial-rotation-gravity' theme if some supplimentary technology like gravitonics is required to hold the place together. I have no problem with the idea of hyper-tensile material holding the place together. In fact, we already know of one that could do it. It's just that the theory doesn't hold water, or air, rather. Assuming that Halo has a 'g' of about about 9.8 m/s^2 like Earth, we find that it would need to have a tangential velocity of about 400 m/s: a = v^2 / r -> 10 m/s^2 = (400 m/s)^2 / 16000 km Please pardon the sloppy numbers, as I don't have a reference book on hand; they're close enough for my point. The main fact to be grabbed, though, is that the land is revolving to the tune of 400 m/s underfoot, which is a pretty good clip, though still noticably slower than some bullets. The other relevant knowledge is that normal-force 'gravity' only affects an object if it is in direct contact with, or under the indirect influence of, the spinning object. Imagine standing in the middle of a merry-go-round with a hole in the center and you will get a pretty good idea of the concept; you are pretty much immune to the spin and its effects until you grab onto the inner rim. A spaceship could fly through Halo and feel no effect until it tried to land (though purportedly, there were _crash_ landings that might not have been intentional. hmm...). As such, anything flying through Halo's atmosphere or above (in between, whatever) at 400 m/s (or less as you go 'up', or inwards) counter to the rotation of the ring could be put into an internal orbit for a song (or a couple ounces of gun powder). The theoretically crushing concept though, is that Halo would hold air about as well as a burlap sack. Because the speed of sound is around 330 m/s at 1 atm (depending who you ask, at what time of day, and where), logic would dictate that some of air molecules have to be moving faster than this (as some are moving slower, through a distribution curve) so that the average rate of signal propogation would be as high as it is. As a matter of fact, actual air molecules can and do move much faster than our magic speed of 400 m/s. Because of this, ANY air molecules moving at or above this speed against the direction of rotation at the 'top' of Halo's atmosphere would be free of the indirect normal forces imposed by the ground belo! w ! (the ground _would_ carry winds around with it at its tangential speed, keeping most air moving in the right, gravity simulating, direction). By the chaotic forces of heat, Halo's atmosphere would be bled dry as whifts of the upper atmosphere escaped into space. Though natural gravity be weak, its reach is infinite, and I for one am glad that Earth keeps its air the good old-fashioned way. I leave the other possible anomalies involving projectile weapons and aeronautical travel to the reader's imagination. I can only hope the Bungie simulates them. --Jeffrey Smith P.S. Halo obviously _does_ have an atmosphere, though, so some other, unimaginable force is keeping it habitable. Suffocation isn't its only obstacle, though; it has to deal with other issues like gravitational rotational friction and gyroscopic torque. Maybe I'll write in about these, too, if I don't get torn to shreds about this post. :) |
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