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waterfall
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Are there different kinds of metric in GR? For instance. I read in http://www.astronomy.ohio-state.edu/~dhw/A682/notes3.pdf there the FRW Metric is about:
"In 1917, Einstein introduced the first modern cosmological model, based on GR, in which the spatial metric is that of a 3-sphere:"
Why. Can the GR metric be based on 2D, 3D, 3-sphere, 3-cube? Can you give other examples?
What would happen to the EFE if you change the metric?
Btw.. is the FRW metric about space or about spacetime?
"In 1917, Einstein introduced the first modern cosmological model, based on GR, in which the spatial metric is that of a 3-sphere:"
Why. Can the GR metric be based on 2D, 3D, 3-sphere, 3-cube? Can you give other examples?
What would happen to the EFE if you change the metric?
Btw.. is the FRW metric about space or about spacetime?
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