## Profile: Dr. John Baker

# John's Big Question

**Simulation of gravitational radiation (waves)... was Einstein right about black hole mergers?**

We have made tremendous progress recently in understanding the predictions of Einstein's theory of gravity (general relativity) for what happens when black holes merge. But we don't yet know whether these predictions are correct. The part of Einstein's theory governing the strong interactions of black holes, which our group studies with numerical simulations, remains untested. High-precision gravitational wave measurements of black hole mergers, such as those LISA will conduct, will provide measurements of strong-field gravity unlike any before.

The gravitation dynamics of these systems are in some ways far removed from the familiar gravity of the solar system, where many tests of Einstein's theory have been conducted. If Einstein's insight nearly 100 years ago, rooted in basic physics principles and weak-gravity observations, turns out to make correct predictions, it will have been an incredible achievement of scientific induction. If not, LISA's measurements may provide the basis for a new, even more profound, theory of gravity.

*Publication Date: January, 2010*