Wednesday, August 14, 2013

What "Hitchhiker's Guide to the Galaxy" is really about

I was on holiday recently lying on a meadow somewhere near Furka pass in Switzerland. It was the middle of the night and the sky was cloudless. Far from any civilization I could see the night sky in all its glory - with all the tiny stars and the clear shape of the Milky Way. Truly stunning view!

Coincidentally I was also reading Douglas Adams "Hitchhiker's Guide to the Galaxy". It's brilliant! Funny and smart. It struck me what it really is about. Let me give you a hint by quoting a paragraph:

"Han Wavel is a world which consists largely of fabulous ultra-luxury hotels and casinos, all of which have been formed by the natural erosion of wind and rain. The chances of this happening are more or less one to infinity against. Little is known of how this came about because none of the geophysicists, probability statisticians, meteoranalysts or bizzarrologists who are so keen to research it can afford to stay there."

Yes! It is basically saying that because the universe is so vast, the probability of extreme events (such as spontaneous formation of luxury hotels) happening by pure chance is not that low. This is nothing else than the problem of family of statistical test and multiple comparison correction. The longer you draw samples from a random distribution the more likely it is that you will find one very extreme value!

Of course I cannot fool anyone that H2G2 is about multiple comparison correction. Obviously it's about life, the universe and everything. It is just my personal bias. Being obsessed about a certain problem I'm more likely to find patterns related to it. This is, however, a topic for a whole new post :)