It was recently claimed that the mass of the Milky Way can be measured using a small 10 cm Michelson-type interferometer located on the surface of the Earth. Using the Kerr metric to model the Earth located in the gravitational field of the Galactic centre, light travel times were calculated along the orthogonal directions of the interferometer arms. The difference in travel times was proportional to the Galactic mass and the size of the effect was found to be measurable.

We have investigated the claim, both analytically and computationally, and found it to be an artefact of the simplifying assumptions employed in the analysis. The physical situation pertaining to the claim has been modelled in a numerical experiment in GRworkbench, an ongoing project in visual, numerical General Relativity at The Australian National University, without the necessity of making any simplifying assumtions. An accurate estimate of the effect for the Milky Way, the Sun and the Earth has been obtained.