By | September 05 2012 6:34 AM

In the first century of the common era, the Greek historian Plutarch reported on a question that had vexed philosophers 300 years prior: that of whether a ship that was taken down and rebuilt plank by plank would still be considered the same ship after restoration. In the 18th century, Irish intellectual George Berkeley wondered whether a tree falling in a forest with no witness to the event could be understood to make a sound. In 1935, Austrian physicist Erwin Schrödinger mused on the fact the standard model of quantum mechanics allows for a cat, in certain experiments involving feline elements, to be simultaneously alive and dead.