Symbol phi

The passage around this formula

…surveying, where 1\,$\mathrm E$ = 10^{-9}\,$\mathrm{s^{-2}}$ . Under a rotation of the local spatial axes it transforms as an ordinary rank-two tensor; under a change of which node is used as the additive reference for $\phi$ it is unchanged, because it depends only on derivatives of $\phi$ , never its value; and up to the factor $U^2$ $\approx$ 1 negligible at the one-part-in- 10^9 level for any terrestrial network, it is $c^2$ times the frame component $R^i${}_{0j0} of the Riemann tensor in the static observers’ own rest…

Read this part in the article →