Isn't it remarkable what an education can do for a person? ... I recall once I invented a simple computer for doing arithmetic; cutting some notches in the pencil slot on my desk, much too young to realize I was defacing public property but had I given it any thought I would have esteemed it a worthwhile permanent improvement. To add 2 + 3? insert pencil at left, move 2 clicks, then three. Count the clicks running backwards; 5! But when Teacher heard the racket, she came back to see what was going on, and the rest is history. No Nobel Prize! Two tides a day is interesting; it is the quadrupole moment, not the dipole moment. The dipole moment keeps the Earth in orbit around the moon. Funny thing: water on the near side of the Earth falls toward the moon, but the Earth falls away from the water on the back side, and you get two bulges. But there is some friction and a phase lag so you don't get high water just under the moon. And no, it isn't due to the finiteness of the velocity of light (or gravitation either). How are you going to explain dipole and quadrupole moments to a fifth grader? Probably thinks there are tripole moments and they come next after the dipoles. It's off to the beach to see if the wind has anything to do with it. Sigh ... - hvm ------------------------------------------------- Obtén tu correo en www.correo.unam.mx UNAMonos Comunicándonos