Changes

: Relativity does imply that space as well as space-time are curved.  The observation of a flat universe does contradict what would be expected if Relativity were true.--[[User:Aschlafly|Andy Schlafly]] 10:03, 13 August 2010 (EDT)

: Relativity does imply that space as well as space-time are curved.  The observation of a flat universe does contradict what would be expected if Relativity were true.--[[User:Aschlafly|Andy Schlafly]] 10:03, 13 August 2010 (EDT)

:: A trivial solution to Einsteins field equations for a vacuum can result in Minkowski spacetime. This is a 4D metric describing a pseudo-Riemannian manifold with no spatial curvature (i.e. flat). A requirement of GR is that in locally inertial frames (i.e. small enough regions of spacetime) we recover Minkowski spacetime. It's just that in GR the requirement of a locally Minkwoski spacetime does not always extend to a global case with curvature effects breaking down the notion of inertial frames for all observers. The observation of a flat Universe (spatial curvature parameter, K = 0 in the FLRW metric) is not in violation of GR and is a valid solution to Einsteins field equations (see e.g. [http://en.wikipedia.org/wiki/Friedmann_equations|Friedmann's Equations]) and a prediction of models of inflationary cosmology whereby a rapid expansion in the early Universe drives the Universe towards a spatially flat solution, certainly within the observable Universe. Predictions from GR are still obeyed... 14th August 2010

:: A trivial solution to Einsteins field equations for a vacuum can result in Minkowski spacetime. This is a 4D metric describing a pseudo-Riemannian manifold with no spatial curvature (i.e. flat). A requirement of GR is that in locally inertial frames (i.e. small enough regions of spacetime) we recover Minkowski spacetime. It's just that in GR the requirement of a locally Minkwoski spacetime does not always extend to a global case with curvature effects breaking down the notion of inertial frames for all observers. The observation of a flat Universe (spatial curvature parameter, K = 0 in the FLRW metric) is not in violation of GR and is a valid solution to Einsteins field equations (see e.g. [http://en.wikipedia.org/wiki/Friedmann_equations | Friedmanns Equations]) and a prediction of models of inflationary cosmology whereby a rapid expansion in the early Universe drives the Universe towards a spatially flat solution, certainly within the observable Universe. Predictions from GR are still obeyed... 14th August 2010

== Reversion explained ==

== Reversion explained ==