p******s
发帖数: 62 | 1 If universe is flat, what is the age? How is the age related to the
curvature of the universe?
Pure curious. | s*****n
发帖数: 209 | 2 When people say that recent observational evidence suggests that
the universe is flat, they mean that the spatial section of
the universe is flat. The metric for the cosmological model is
ds^2 = -dt^2 + a(t)^2 ds_3^2
where ds_3^2 = dx_1^2 + dx_2^2 + dx_3^2 instead of spherical or
hyperbolic metrics. The four-dimensional spacetime is not flat,
since the only flat spacetime in D=4 with Lorentian signature is
Minkowskian.
The age of the universe can be measured regardless whether |
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