Spacetime and Geometry · Problem 7.2

Cosmology — Sean Carroll

Physics — General Relativity · gravitomagnetism-lense-thirring

Problem

Consider a thin spherical shell of matter, with mass MM and radius RR, slowly rotating with an angular velocity Ω\Omega. (a) Show that the gravito-electric field G⃗\vec{G} vanishes, and calculate the gravito-magnetic field H⃗\vec{H} in terms of MM, RR, and Ω\Omega. (b) The nonzero gravito-magnetic field caused by the shell leads to dragging of inertial frames, known as the Lense--Thirring effect. Calculate the rotation (relative to the inertial frame defined by the background Minkowski metric) of a freely-falling observer sitting at the center of the shell. In other words, calculate the precession of the spatial components of a parallel-transported vector located at the center.

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