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Different representations of the Levi-Civita Bertotti Robinson solution
Oyvind Gron, Steinar Johannesen
The Levi-Civita Bertotti Robinson (LBR) spacetime is investigated in various coordinate systems. By means of a general formalism for constructing coordinates in conformally flat sp…
A physical interpretation of Hubble's law and the cosmological redshift from the perspective of a static observer
Simen Braeck, Oystein Elgaroy
We derive explicit and exact expressions for the physical velocity of a free particle comoving with the Hubble flow as measured by a static observer, and for the frequency shift of…
A solution of the Einstein-Maxwell equations describing conformally flat spacetime outside a charged domain wall
Oyvind Gron, Steinar Johannesen
We derive and discuss the physical interpretation of a conformally flat, static solution of the Einstein-Maxwell equations. It is argued that it describes a conformally flat, stati…
FRW Universe Models in Conformally Flat Spacetime Coordinates. III: Universe models with positive spatial curvature
Oyvind Gron, Steinar Johannesen
We deduce general expressions for the line element of universe models with positive spatial curvature described by conformally flat spacetime coordinates. Models with dust, radiati…
FRW Universe Models in Conformally Flat Spacetime Coordinates. II: Universe models with negative and vanishing spatial curvature
Oyvind Gron, Steinar Johannesen
We deduce general expressions for the line element of universe models with negative and vanishing spatial curvature described by conformally flat spacetime coordinates. The empty M…
FRW Universe Models in Conformally Flat Spacetime Coordinates. I: General Formalism
Oyvind Gron, Steinar Johannesen
The 3-space of a universe model is defined at a certain simultaneity. Hence space depends on which time is used. We find a general formula generating all known and also some new tr…