A rigorous mathematical definition of such concepts (for a given 3D “spatial domain slice” – with a fixed time-coordinate in 4D spacetime) should be based on the 4D spacetime metric.

A well-known example is the Kerr-Newman blackhole metric which is completely described by its intrinsic parameters (mass, electric charge, and vector angular momentum).

]]>A lot of mumbo-jumbo. Plain english is missing.

A well understood topic should be easy to communicate. ]]>

“c is also the speed of gravitational propagation” This isn’t true, the speed of propagation of Einstein’s ‘gravitational waves’ is arbitrary because it is coordinate dependent.

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