I'm trying to remember where I read it, but it HAS been calculated how much the earth's rotation has been slowed by various forces, including tides, over the last couple of billion years. I believe it amounts to about ¼ second per century...or something like that. Meaning a few minutes in billions of years.


awww..never mind. It took about 5 seconds to get the wikipedia page with the info.

"Atomic clocks show that a modern day is longer by about 1.7 milliseconds than a century ago,"