Sniffing out an explanation

In laboratories up and down the country there are chemists who have the misfortune to work with thiols. Some of these whiffy molecules have a stench so pungent, so disgusting, that they have been known to empty entire buildings when a few drops are spilled in the wrong place.

But why do thiols smell so bad? The answer is surprisingly complicated, and scientists are still arguing about it. It’s strange to think that smell remains a mysterious process.

You would think that vision – which we understand quite well – would be a much more complicated sense than smell. But actually our eyes only have to detect one thing: photons (albeit with different wavelengths). Whereas our noses are chemical sensors: capable of identifying thousands of different molecules.