What is general relativity? - Professor David Tong explains to Plus

What is general relativity? When physicists talk about Einstein's equation they don't usually mean the famous E=mc2, but another formula, which encapsulates the celebrated general theory of relativity. Einstein published that theory a hundred years ago, in 1915. To celebrate its centenary Plus (plus.maths.org), our free online mathematics magazine, asked physicist Professor David Tong of the University of Cambridge to explain what general relativity is and how Einstein's equation expresses it. Watch his explanation in this video, or read more in his article on Plus at plus.maths.org/content/what-g...