General Relativity and Cosmology
General relativity is Einstein’s theory of gravity and is the basis for understanding the large scale structure and history of the universe. Although the theory is almost 100 years old, the process of determining exactly what it predicts still continues. The theory predicts that many astrophysical events will generate gravitational waves, ripples in the geometry of spacetime. What waveforms should our gravitational wave detectors look for?
The theory is unique in predicting its own breakdown through the formation of singularities. The best known example of a singularity is the Big Bang that started our universe. Is that the only example or is it possible to generate a singularity that can affect other things? Such a thing is called a “naked singularity.” The conjecture that Einstein’s theory forbids such naked singularities is called “Strong Cosmic Censorship” and remains unproven. Theorists are still at the stage of seeking counterexamples to the conjecture in order to sharpen our understanding of it.
The theory has passed every experimental test so far, but is widely thought to be just a very good approximation to the correct theory of gravity. Candidates for the correct theory include string theory (in its many manifestations) and loop quantum gravity. There are also a number of candidates for a theory that is simply a better approximation without being the final answer. These include the Randall-Sundrum model and other theories in which our universe is a subspace of a larger one.
At VCU our research includes exact solutions of Einstein’s field equations that have been used to validate the computer codes that predict gravitational waveforms from astrophysical sources and have also been used in the most extensive search to date for counterexamples to the Strong Cosmic Censorship Conjecture. Current research at VCU includes a search for geometrically natural generalizations of Einstein’s theory.