The Final Frontier for Einstein’s Theory of Gravity
In 1914, Einstein brought forth his foundations for General Relativity (GR) to explain gravity using the geometry of space and time. Einstein’s GR ushered in the beginning of a new scientific paradigm shift for the science of the origin and development of the universe (“Cosmology”). This is now a golden age, similar to the centuries around Plato, Copernicus and Newton, and we are privileged to be witnesses to this paradigm shift in real-time. All scientific paradigms go through a long period of intense testing, as the data and the scientific methods push the theory to its limits. A primary goal of cosmologists is to test GR to strengthen and harden the theory until it becomes a natural law. Einstein’s original theory of GR has so far survived all tests against it.
However, the Universe is vast and there are physical scales on which GR should apply, but which are also so large that it has been difficult to test. Consider clusters of galaxies, which are the largest gravitationally bound objects in the Universe. Clusters entrap galaxies on scales of tens of millions of light years (i.e, 100 times larger than our own Milky Way). Does GR still apply over such large distances in space-time? A consequence of GR is that matter/energy tell space-time how to geometrically curve. This curvature bends light and tells matter/energy how to move. New astronomical instrumentation is providing cosmologists the data to combine the bending of light with the dynamics of the trapped galaxies in clusters to test GR on the largest possible scales. The final frontier of general relativity is within reach. Will Einstein again be proven correct? Or will these data open the door to a new shift in our cosmological paradigm?
Christopher Miller is Associate Professor at the University of Michigan and Asa Briggs Fellow at the University of Sussex. During his Fellowship Prof Miller will be collaborating with Professor Kathy Romer on the project Using Clusters of Galaxies to study the Dark Universe. The project will focus on the characterization of Dark Matter and Dark Energy using clusters of galaxies.