Nice Going, Einstein

One of the great paradoxes of physics is that while gravity was the first force in nature to be described physically and mathematically—Isaac Newton worked out its basic laws more than 300 years ago—it may be the last to be understood. Generations of physicists have remained stumped by the utter strangeness of gravity: Not only is it the weakest of the four natural forces, but it is also the only one that appears to be directly related to the nature of space and time. Still, theorists steadfastly continue to wrestle with the problem, dreaming up extra dimensions or, as in Mordehai Milgrom's case, proposing new versions of Newton's classic equations.