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发帖数: 53 | 1 【 以下文字转载自 Joke 讨论区 】
发信人: Albacore (LongFin), 信区: Joke
标 题: Re: 三体是很棒的科幻小说，虽然其基本思想不科学 (转载)
发信站: BBS 未名空间站 (Mon Apr 21 13:23:15 2014, 美东)
Also the effective gravitating mass at the center of gravity is not the
total mass of the system. It depends on the explicit spatial mass
distribution and changes over time in a 3-body system.
I can give a simple example that illustrates the point.
Consider a empty sphere S^2 (empty both in and out of the sphere, like a
Ping-Pang ball) that has static, homogeneous mass distribution.
A test body in the inner space of this sphere do not experience any gravity
(since the contribution from different part of the sphere perfectly cancels)
.
It is either static or moves with a constant velocity until it hits the
inner wall of the sphere. But according to lz it will orbit the center of
the sphere, which is not what it does. |
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