» Urban Legends

You spin me right round baby
CDs and DVDs in Australia (or indeed, anywhere far south of the equator) have to go the other way around, and are therefore incompatible with UK/US/Canadian equipment.

Honest! Why? Well, surprisingly quite simple when you think about it. As we all know, manufacturing processes are never perfect, and so the discs are rarely perfectly circular. This imperfection results in significant wobbling when the discs are spun really fast -- something that the players hardware has to be able to correct for. Unfortunately, when the disc is spinning in the opposite direction to the earths rotation, the Coriolis effect induces instabilities that hardware of the player is unable to correct for (due to requiring third and higher order differential stability correction in the mechanical hardware), so therefore the player (and discs) have to be manufacturered to rotate in the direction /matching/ the spin of the earth in the region that the player is manufactured from.

This is why you can swap UK and US discs, but Australians can't use discs from the US/UK and vice-versa.
(Fri 6th Jan 2006, 0:56, More)