John,

How long has GPS been available worldwide? Is there there a test to confirm it's correct?

There's always room for debate in science. Not everyone hops on everyone elses bandwagon all of the time. That's why it has taken 50 years for most to accept plate tectonics. Note I said, most. Not all of you are on the same page in the book and even at that, who knows that in another 50 years what is thought to be correct now will be reversed, modified, redirected or tunneled into something else. Perhaps Earth Expansionism into Earth Protuberant Theory.

When one looks across scientific disciplines it's interesting to hear most scientists being aware of one theory to the next, but expanded upon greatly by those outside of geosciences. The world is much richer and fuller from a multi-sided discussion. It leaps outside of the box, yet keeping inside of basic fundamentals. Sometimes it's good to not know everything or appear to know it all because information doesn't come as a challenge, but rather to broaden a point of view, which is complimentary.

I heard a new song the other night and it may take a year to gather all of the instruments needed to replicate the orchestra, however in the end the music will be of such a quality I'm sure it won't be like anything ever assembled before. You should ask Knopoff sometime why music and geophysics are connected.

Petra