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How do you create dramatic film out of mathematics? We find out with writer and director Timothy Lanzone.

Mathematics plays a central role in understanding how infectious diseases spread. This collection of articles looks at some basic concepts in epidemiology to help you understand this fascinating and important field, and set you up for further study.

Find out why the formula we use to work out conditional probabilities is true!

- We talk about a play that explores the fascinating mathematical collaboration between the mathematicians GH Hardy and Srinivasa Ramanujan.
News stories have claimed they may have — but is this true?

I'm inclined to agree and suggest going a bit deeper. The confusion between prior and posterior probabilities results from the fact that no decision is in fact made, however much we think we're seeing into what would happen were it made, so no new information is in fact ever learned. And that decision was never made because it was revoked before being implemented and nothing changes, including information. If a decision does change anything, then it can't be revoked or switched, at least not without cancelling the resulting information changes too.

In this crucial respect the two envelopes problem differs from Monty Hall (which some people compare it to), since in the latter the first decision does result in new information which the player can then use for their next. But switching doors doesn't mean they're revoking their first decision. They can't.

(When I finally hit the SAVE button, I can't change anything either. Oh well, here goes)