This column first ran in The Tablet in December 2015 One hundred years ago, Albert Einstein published his theory of General Relativity and changed the way we understand our universe. Newton had shown, 200 years earlier, that one could use mathematics (including his newly invented Calculus) to describe and even predict the way things in our physical universe move. But to do that, Newton had had to assume without definition the concepts of space, mass, and time. He had to assume that forces like gravity acted “at a distance”… Earth could pull on the Moon even if there’s nothing but this mystical “gravity” connecting them. Finally, he had to envision a playing field, the “inertial frame of reference”, where these forces could move those masses through space, over time. The whole genius of physics is to describe motion and change; but change, relative to what? Newton’s unmoving frame of reference was his answer. But was the Earth’s surface such a … Continue reading →