Peres metric

In mathematical physics, the Peres metric is defined by the proper time



{d \tau}^{2} = dt^2 - 2f(t+z, x, y) (dt+dz)^2-dx^2-dy^2-dz^2 $$

for any arbitrary function f. If f is a harmonic function with respect to x and y, then the corresponding Peres metric satisfies the Einstein field equations in vacuum. Such a metric is often studied in the context of gravitational waves. The metric is named for Israeli physicist Asher Peres, who first defined it in 1959.