Robert B See in teal. Jack L Therefore why aren't Michaelson and Morely et al scientific heroes? I'm on very shaky ground here, but my understanding is that the experiment to which you are probably refering was interpreted by the two 'camps' to have had different conclusions. Had the non revolving Earth conclusion been correct, then the way the universe works would have been very different from the way it is understood to work. [Robert Bennett] The difference in understanding between GC and HC/AC would be very great. However the difference in observations would be very slight (Agreed) - the difference between aether and gravity has only been detectable for about a century. But more GC proofs are unfolding each day. (No doubt you will keep us informed). In this position, I'd venture the guess that none of the space missions outside the Earth/Moon system would have succeeded, instead of which a quite large proportion have succeeded hansomly. [Robert Bennett] The old canard - that you must use HC to navigate in the Solar System - is contrary to general covariance and exposed in GWW as a myth promoted by a certain USA space agency. (Well this '...old canard...' has intrigued me for as long as I've been exposed to GC. I cannot imagine what physics could be employed to plot the navigation as GC doesn't seem to run on physics but rather on mysticism for which there are no rules. Do you have a comment or is this propriety to GWW?) Does ESA insist that they use HC navigation - because they must? (Not clear. They must insist? Or they have some other reason for insisting? Or other?). On shaky ground... yes then why venture the guess? (Because I'm basically a polite person and I was asked). RB Paul D ____________________________________________________________________________________ Yahoo!7 Mail has just got even bigger and better with unlimited storage on all webmail accounts. http://au.docs.yahoo.com/mail/unlimitedstorage.html