Radio telescopes have been crucial to some significant discoveries regarding the nature of the universe. Now, though, they're verifying the basic rules of the cosmos. An international group of astronomers has shown that Einstein's theory of gravity holds up even in more extreme situations. The team spent six years using a trio of radio telescopes (Arecibo, Green Bank and Westerbork Synthesis) to track an unusual three-star system with a pulsar bracketed by two white dwarfs -- a textbook example of extreme gravity in action. How that pulsar moved would determine whether or not Einstein's concept passed muster.