← All parts of this equation

Equation 78 · Part 4 · The Bend an Elevator Cannot Fake

Symbol x

ds2=−U(x)2 dx02+δij dxidxjds^2 = -U(\mathbf x)^2\,dx_0^2 + \delta_{ij}\,dx^i dx^j
xx

What this part means

x is one of the signed contributions combined to compute the quantity on the left.

Its job in the formula

x is one of the signed contributions combined to compute the quantity on the left.

The passage around this formula

What must therefore vanish, identically, is not the slope but the correctly defined curvature-frame component built from it. For any static metric of the form ds2s^2 = -U(x\mathbf x)^2\,dx02x_0^2 + δij\delta_{ij}\,dxix^i dxjx^j — flat spatial slices, all the position dependence carried by U — the only nonzero Christoffel symbols are Γ0i0\Gamma^0_{0i} = ∂i\partial_i ln⁡\ln U = ϕ,i\phi_{,i} and Γ00i\Gamma^i_{00} = U2U^2ϕ,i\phi_{,i} , both following directly from the metric’s definition. Substituting into…

Read this part in the article →

Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

Open the illustrated variables: a letter stands for a value guide →

See this notation across published equations →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.