If you find yourself crying when chopping onions, physicists have found a possible solution – but professional chefs probably aren’t going to like it.

When onions are cut open, they spray a mixture of sulphur-rich compounds into the air, one of which is syn-propanethial-S-oxide, a chemical that triggers the nerves in the eye responsible for producing tears.

Sunghwan Jung at Cornell University in Ithaca, New York, and his colleagues used a high-speed camera to analyse in detail the spray produced when…