Hm...I've seen that alleged before, but...
Taking out the oceans, the difference between the highest point on Earth (Mr. Everest) and the lowest (Mariana Trench) is about 13 miles...that's roughly one part in six hundred as compared to the Earth's diameter.
http://en.wikipedia.org/wiki/Ball_%28bearing%29
As I read the chart, the highest grade ball bearings (Grade 3), which have a diameter of up to 2 inches, have a maximum variation in diameter of 0.000003 inches...which is a heck of a lot smoother than the Earth, being a variation of only one part in 600,000!
Hmmm. Good to know. Thanks!
Hey Kip, is you a scientist fella, or does ya just read about ‘em?