Since we have a philosophy thread section... how about a good ol paradox to get everyone's brain running??
Ship of Theseus
There once was a ship whose captain was named Theseus. This ship was made of a large number of parts. One day (we’ll call this day D1) Theseus and his crew set out on a long voyage. On D1, the Ship of Theseus consisted of a determinate set of physical parts. As the voyage moved along, the crew recognized that they would occasionally have to make repairs to the ship, sometimes throwing old planks overboard and replacing them with new planks. After a long while, on Day 3002, it turns out the crew had replaced every part of the ship and there were no longer any original parts left. The question that naturally arises here is whether the Ship of Theseus on Day 3002 is the same ship as the Ship of Theseus on Day 1, even though they share none of the same physical parts.
Now suppose that, unbeknownst to Theseus and his crew, there had been a man collecting all the old parts of the original Ship of Theseus (the ship as it was on Day 1). Let us further suppose that on Day 3002, when he collects the final discarded part, he completely rebuilds the ship with nothing but the original parts. Now, we find ourselves with two candidates for the Ship of Theseus. Which one, if either, is the actual Ship of Theseus?
Penny for your thoughts?