# Re: (TFT) hollow Cidri

```At 01:09 AM 2/5/06 -0600, David Michael Grouchy II wrote:
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So in answer to your question, a person (P) standing inside or outside will be 6km from the center and feel equal gravity.
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To get a little more picky and technical about this one point (confused people, just ignore - this isn't going to help, sorry):
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Hmm, assuming an equal distribution and a small enough radius, I would say there would be a difference, because on the outside, the curved parts are "down" relative to someone standing on the outside, but they are "up" relative to someone standing on the inside, so gravity would tend to be to some degree less for someone on the inside, though maybe the distribution could be tweaked to make them identical, if desired. Also, if Cidri is as big as ITL suggests, though (so big that it's essentially flat), then it would be essentially flat for gravity calculation purposes too, so yes.
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The interesting thing about the subtractive nature of an anti-grav center is that a person will feel attracted to which ever center point (0) they are closest too.
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That would be true even without an anti-grav center, wouldn't you say? I assume the reason you want an anti-grav center is to try to get exactly the gravity numbers you want (but not really the direction), no?
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And on that journey to the surface from inside? The gravity will become much much stronger as they near the zero (0) and then get weaker as they near the outside surface.
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I believe you have that backwards. Just like in the middle of the Earth (or, probably, off some distance because of the curvature of the shell, at your zero point, with your anti-grav center balanced for 1g at the surface, there would be zero gravity, and not more than 1g, as you wrote. Gravity goes steadily down as you get closer to the zero point, because the mass "over your head" is pulling you up, not down.
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PvK
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