My physics professor showed me that exact proof 20 years ago. I remember being amazed. He used alpha instead of F as the scale factor :) Still, it's easier for

My physics professor showed me that exact proof 20 years ago. I remember being amazed. He used alpha instead of F as the scale factor :) Still, it's easier for me to believe that it was attributed to Einstein at some point in the past 60 years than it originated with him.