Abstractly, perfect spheres exist, but they are all self-similar in form. Physically, in nature, are there perfect spheres, wthout any irregularities? The only way to measure an irregular surface is via fractals. http://www3.amherst.edu/~rloldershaw/NOF.HTM No, I did NOT. A person can change his name for any number of reasons. Almost all women change their name when they get married. And if Tegmark changed his name for commercial reasons is perfectly acceptable to me and to me not noteworthy. Sorry, that was my error, I was looking at another sub-form at the time. Sloppy....Please Register or Log in to view the hidden image! The illustration showed that "Ad Hominem" attacks the characteristics or the authority of the writer without addressing the substance of the argument and is therefore not a valid "argument" in the Science and Physics sub-forum.