Einstein's Lost Key - How we Overlooked the Best Idea of the 20th Century

Einstein's initial idea of general relativity was a variable speed of light theory. This talk (Title: Einstein's Unrecognized Masterstroke, given at the DPG Meeting in Berlin 2015 ) focuses on the historical aspects of this ingenious attempt of Einstein during the years 1907-1911. It is a widely underestimated, equivalent form of general relativity that allows for a Machian interpretation of gravity. Other aspects are addressed in the Book "Einstein's Lost Key": https://www.amazon.com/dp/B01FKTI4A8