1207.2510 (J. W. Maluf et al.)

Gravitational wave measurements and the breaking of parallelograms in
space-time    [PDF]

J. W. Maluf, S. C. Ulhoa, J. F. da Rocha-Neto

We consider a simple experiment to detect plane-fronted gravitational waves, similar to the experiments that are expected to lead to gravitational wave measurements. In the present setup, an incident beam of light splits into two beams running along perpendicular arms, in similarity to the arms of the standard gravitational wave interferometers. The two arms have the same length, and each one has a fixed mirror at the end. The reflected light beams are detected at the same point of the splitting. Along each arm of the setup, the two light beams define two null vectors in space-time: the forward vector and the reflected vector. We show that the sum of these four vectors, the forward and reflected null vectors along the two arms, do form a parallelogram in flat space-time, but not in the presence of a plane-fronted gravitational wave. The non-closure of the parallelogram expresses the existence of gravitational waves, and is a manifestation of the torsion of the space-time. The present setup is an alternative and well suited procedure that may improve the detection of gravitational waves.

View original: http://arxiv.org/abs/1207.2510