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Equation 71 · Part 12 · The Bend an Elevator Cannot Fake

Symbol g

ds2=−U(Z)2 dx02+dZ2+dx2+dy2,x0:=ct,U(Z):=1+gZc2.ds^2 = -U(Z)^2\,dx_0^2 + dZ^2 + dx^2 + dy^2, \qquad x_0 := ct, \qquad U(Z) := 1 + \frac{gZ}{c^2}.
gg

What this part means

the observer under constant proper acceleration.

Its job in the formula

g occurs above the fraction bar. The numerator is divided by the entire denominator below it.

Where the article explains it

Consider a uniformly accelerated laboratory in otherwise empty, flat spacetime — Einstein’s elevator, given by the exact Rindler metric in coordinates comoving with an observer under constant proper acceleration g : ds2=−U(Z)2 dx02+dZ2+dx2+dy2,x0:=ct,U(Z):=1+gZc2ds^2 = -U(Z)^2\,dx_0^2 + dZ^2 + dx^2 + dy^2, \qquad x_0 := ct, \qquad U(Z) := 1 + \frac{gZ}{c^2}.

The passage around this formula

Consider a uniformly accelerated laboratory in otherwise empty, flat spacetime — Einstein’s elevator, given by the exact Rindler metric in coordinates comoving with an observer under constant proper acceleration g : ds2=−U(Z)2 dx02+dZ2+dx2+dy2,x0:=ct,U(Z):=1+gZc2ds^2 = -U(Z)^2\,dx_0^2 + dZ^2 + dx^2 + dy^2, \qquad x_0 := ct, \qquad U(Z) := 1 + \frac{gZ}{c^2}. This is an exact solution describing flat Minkowski spacetime in non-inertial coordinates, not a weak-field approximation. A clock held static at height Z has dτ\tau = U(Z)\,dt exactly, so two such clocks compare frequencies as ν2\nu_2/ν1\nu_1 = U(Z1Z_1)/U(Z2Z_2) to all orders — the…

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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.

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Sources cited in the article section

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