I view a physical impossibility as one contingent on the laws of the
universe we occupy, while a logical impossibility is impossible across
all possible universes. This makes the logical impossibility more
general, and in a sense, more fundamental.
e.g. As far as we know it is impossible for a massive object to travel
at 400,000 km/s, but we can imagine another universe where the speed
of light is different. It is logically impossible to be simultaneously
travelling faster than light and slower than light (relative to the
same object).
-- David McFadzean david@lucifer.com Memetic Engineer http://www.lucifer.com/~david/ Church of Virus http://www.lucifer.com/virus/