發信人: EPS.bbs@bbs.ntu.edu.tw (貓咬豬), 看板: astronomy
標  題: Re: 什麼是馬赫原理?
發信站: 台大計中椰林風情站 (Tue Apr 22 14:15:51 2003)
轉信站: Lion!news.nsysu!news.civil.ncku!netnews.csie.nctu!ctu-peer!news.nctu!ne

==> graddivcurl@bbs.ee.ntu.edu.tw (為所應為) 提到:
> ※ 引述《EPS.bbs@crux.chem.nsysu.edu.tw (觀測如作戰)》之銘言：
> : 不論如何,廣義相對論與馬赫原理在某種程度上似乎是被曖昧地連結在
> : 一起,廣意相對論是某能成為馬赫原理的終極解答? 到目前為止我還沒聽過
> : 有人說是或不是的,大家都看得到那個曖昧但有趣的連結,但沒人有真正的
> : 答案....
> While most of my GR books are in Taiwan, I still may say something about it,
> based on my memory & Ohanian & Ruffini's text.
> In a wider sense, Mach's principle only states that matter acts on the
> geometry (Ohanian & Ruffini's text).
> There are several viewpoints (or interpretations) about Mach's Principle.
> In Tolman's text on Relativity, Thermodynamics, and Cosmology, he states that
> the dependence of gravitational field and Metric on the distribution of matter
> and energy is mediated via Principle of Mach. Einstein (in his text on the
> meaning of relativity) formulated Mach's principle as: "The spacetime
> geometry is entirely determined by the energy-momentum tensor of matter".
> Also, Wheeler formulated Mach's principle as the following:
> "The inertial properties of an object are determined by the energy-momentum
> throughout all space". His more precise formulation of Mach's Principle
> is given below: "The spacetime geometry is uniquely determined by the
> energy-momentum and by the initial conditions on the geometry."

I would rather say, all these statements are linked to Mach's
principle but not exactly Mach's principle itself.

For example, the energy-momentum tensor, will change its form when
an observer is moving at constant speed relative to the matter associated
with the tensor.  However, what Mach's principal really states is about
inertia, and therefore acceleration.

Personally I am convinced that these statements about space-time in
GR by various people are all linked to Mach's principle but the link
is vague.

Anyway, it interesting to see all these.
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