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oldman
- 633
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In the cosmology forum I posted this statement:
to which a PF mentor kindly replied:
I fully accept what he says, but would be interested if any of "the GR crowd" would like to comment further.
What I am asking is: by what means does mass/energy shape the geometry of spacetime? Does anybody know? Or is it one of those questions which one shouldn't ask?
,oldman said:All we know is that (at a Newtonian level) masses attract but don't repel, and that (at a GR level) mass/energy distorts spacetime so that geodesics converge. But we don't know exactly how mass/energy accomplishes either feat. Hence gravity remains a given mystery.
to which a PF mentor kindly replied:
Space Tiger said:Well, you should ask the GR crowd for a deeper understanding of the concept of a "gravitational field" in modern physics, but gravitation is generally framed in terms of a metric. This gives the geometry of spacetime, which is shaped by the matter and energy contained within. This matter and energy then moves in response to the local geometry.
Loosely, I suppose you can think of the geometry of spacetime as the "gravitational field" ...
I fully accept what he says, but would be interested if any of "the GR crowd" would like to comment further.
What I am asking is: by what means does mass/energy shape the geometry of spacetime? Does anybody know? Or is it one of those questions which one shouldn't ask?