I was reading an article in Scientific American today regarding the possibility of parallel universes. The article says that mathematical models predict that there is a twin universe at least 10 to the 10 to the 28th power meters away. Suffice it to say that it is very far away, according to this model. This model supposes that space is infinite and that there are an infinite number of universes. Therefore, there must be a twin universe exactly like our own. However, this model falls foul of a common mistake in logic. Just because a set is infinite, does not mean that every possible member of the set exists. There may be possibilities which would fall into the set, but do not exist. This does not make the set any less infinite. In other words, it is not a fact that an infinite number of monkeys banging away at an infinite number of typewriters (or computer weblogs) for an infinite amount of time will necessarily reproduce the entire works of Shakespeare. It might be that they fail to reproduce Trolius and Cressida by leaving out the third act.

The Scientific American article began with this paragraph: "Is there a copy of you reading this artcle? A person who is not you but who lives on a planet Earth, with misty mountains, fertile fields and sprawling cities, in a solar system with eight other planets? The life of this person has been identical to yours in every respect. But perhaps he or she now decides to put down this article without finishing it, while you read on." At that point, I decided to stop reading and take a nap.