Theseus is an ancient Greek character. He was one of the founder of Rome. This story is about his ship. The story is that Theseus had a ship, a tall, beautiful ship in which he came to Rome. The people of Rome preserved this ship long after Theseus was dead. The people replaced the planks as they decayed, they replaced the masts, the sails were repaired and later replaced. These parts were identical to the original parts as the people wanted to preserve the heritage of Theseus. After enough time, all the parts of the ship are replaced. So, is this new ship same as the ship in which theses arrived to Rome? It looks identical to the original, yet Theseus has not put his foot in the deck of this ship. Also, if a ship is constructed out of all the original parts, will this ship be same as the original?
Actually, the ship of Theseus is a paradox, a thought experiment. Same thing can be said about us. Are we the same person that we were 10 years ago? No, we aren’t. The cells of our body are constantly being shed and replaced over a period of time. So, we are not made up of the same matter in the past that we are made up of now. Not only the physical matter but our thoughts, feelings, memories have been altered. Pretty amazing huh!
Another interesting paradox is related to time travel. In this paradox, we imagine a man in an empty room where a mirror is placed in the center. The mirror is a time machine which takes him 10 minutes into his past. What if he was to take a pistol, go through the mirror and shoot himself? Will he be dead? If he is dead, he couldn’t have gone through the mirror to fire a bullet. This is the grandfather paradox.
These kind of paradoxes test our brains and its interesting to know these once in a while. They are usually hard wrap our heads around because they are fundamentally contradictory in nature and our brains have a hard time figuring them out. They may be considered as “brain workouts”!