Background and Motivation
The stress energy tensor of general relativity, as conventionally defined, has sixteen components.
One of those component, conventionally component T00, also called ρ, is mass-energy density, including the E=mc2 conversion for electromagnetic fields.
So imagine you have two disks, and from your perspective one is spinning on its vertical axis and the other one is spinning on its horizontal axis. What do you call that?
And what would it mean to "spin at the opposite polarity" if such a sentence makes any sense at all?
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