From the “I’m Sorry I Asked” Department —
All of my life I’m been hearing about Albert Einstein and his Theory of Relativity. He has had such a huge impact on our lives in general and science in particular. In high school, when I was asked to report on the most consequential figure of the first half of the 20th Century, I chose Albert Einstein. But lately I’ve been wondering, what did Einstein actually say? When he wrote his papers, were they all equations? If so, how many and what were they?
First, some basic facts. Albert Einstein was born in Ulm, Germany on 14 March, 1879. He developed his special theory of relativity while working at the Swiss Patent Office in Bern, Switzerland (1902–1909). Realizing that the principle of relativity could also be applied to gravity, he published a paper on general relativity in 1916 with his theory of gravitation. He was awarded the Nobel Prize in Physics in 1921. (https://en.wikipedia.org/wiki/Albert_Einstein)
Thanks to the internet, anyone can now see his work. I found a Wikipedia entry entitled “Einstein’s Field Equations,” or EFE. There are actually 10 equations in the “general theory of relativity that describe the fundamental interaction of gravitation as a result of spacetime being curved by mass and energy.”
Paradoxically, the entry lists one equation as EFE. Unfortunately, it was a photo and I couldn’t copy it due to “security reasons.” But I can list the variables — Rμν is the Ricci curvature tensor, R is the scalar curvature, gμν is the metric tensor, Λ is the cosmological constant, G is Newton’s gravitational constant, c is the speed of light in vacuum, and Tμν is the stress–energy tensor. If you’re as confused as I am, the Wikipedia entry continues “Despite the simple appearance of the equations they are actually quite complicated.”
No kidding! If you’d like to see for yourself, the entry is at https://en.wikipedia.org/wiki/Einstein_field_equations.
Now I know. As a result of sticking my nose into this, I’ve drawn two conclusions of my own — Albert Einstein really was a genius, and I’m no Einstein.
If you want to go farther, the “Collected Papers of Albert Einstein, Volume 6, the Berlin Years” with an English translation of “the Foundation of the General Theory of Relativity” from the original German is available at https://web.archive.org/web/20120204074848/http://www.alberteinstein.info/gallery/pdf/CP6Doc30_English_pp146-200.pdf .