Yes…I’m still alive and blogging. Just been very busy, as it is coming up to exam-time. Thankfully I think I can safely say that my exam-sitting days are behind me, but there are a lot of anxious students happy to pay good money to someone who will help them pass theirs! Anyway, I recently read an interesting blog post about the axiom of choice, and I thought it would be a good topic to give my usual treatment (that is an attempt to explain it to an interested and patient non-mathematician).
Now, unlike other sciences – in which theories and models are often proposed, used for while, and then modified or just plain discredited by subsequent discoveries – mathematics is constantly building on what has gone before. If sciences were buildings, then mathematics would be a vast complex structure that is constantly being added to: sometimes the foundations would be strengthened, sometimes an extension or a whole new wing would be added, but nothing would ever be demolished. Physics, on the other hand, would be a lot of separate buildings, some of which have long ago been abandoned, and most of the rest of which are in a constant state of being torn down and rebuilt in the modern style! This is part of what drew me to the subject in the first place; the fact that if you prove something mathematically, it is definitely true, and will never be disproved. We still use theorems proved by people that lived thousands of years ago, and it is reassuring to know that anything we prove now will still be being used by people in thousands of years.