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Symbol in context

Σβ\Sigma_\beta

This entry links every published equation using this exact notation. Its meaning may change between equations.

Meanings in context

Article-grounded definition

Symbol Sigma_β

a spacelike hypersurface and uμu^\mu the four-velocity of the observer whose notion of simultaneity Σ\Sigma represents with subscript beta (a directed three-volume element on Σ\Sigma , units of volume).

Read equation 13 in The Atlas That Refuses to Close →

Used in 3 equations

Xμ(u,Σ)=∫Σxμ Tαβuα dΣβ∫ΣTαβuα dΣβ.X^\mu(u,\Sigma) = \frac{\int_\Sigma x^\mu\, T^{\alpha\beta}u_\alpha\, d\Sigma_\beta}{\int_\Sigma T^{\alpha\beta}u_\alpha\, d\Sigma_\beta}.

The Atlas That Refuses to Close · Equation 13

This equation states an equality: the expressions on both sides have the same value under the article’s assumptions.

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