3 June 2015
I spotted this video thanks to Joe Hanson at It’s OK To Be Smart. He said after watching it that he needed to sit down and think for a while. I love reading about relativity, but i agree with Joe!
To get you to watch the 10 minute video, a question: You have identical watches, one you wind up and is running the other is not. Do they have the same mass? (Answer is NO)