The effect of a massive object on an expanding universe

Understand

A tetrad-based procedure is presented for solving Einstein's field equations for spherically-symmetric systems; this approach was first discussed by Lasenby et al.

• in the language of geometric algebra.
• The method is used to derive metrics describing a point mass in a spatially-flat, open and closed expanding universe respectively.
• In the spatially-flat case, a simple coordinate transformation relates the metric to the corresponding one derived by McVittie.