Test of general relativity could potentially generate new gravitational models

A UCLA-led team has discovered a new way of probing the hypothetical fifth force of nature using two decades of observations at W. M. Keck Observatory, the world's most scientifically productive ground-based telescope.

There are four known forces in the universe: electromagnetic force, strong nuclear force, weak nuclear force, and gravitational force. Physicists know how to make the first three work together, but gravity is the odd one out. For decades, there have been theories that a fifth force ties gravity to the others, but no one has been able to prove it thus far.

"This is really exciting. It's taken us 20 years to get here, but now our work on studying stars at the center of our galaxy is opening up a new method of looking at how gravity works," said Andrea Ghez, Director of the UCLA Galactic Center Group and co-author of the study.

The research is published in the current issue of Physical Review Letters.