Physics World April 2021

Cattle battle: measuring methane emissions from cattle

Studying bovine emissions and trying to reduce the amount of methane they emit is a clever, short-term solution to climate change. But the tricky bit is measuring how much methane cows produce in the first place – especially from a herd of them. As Michael Allen explains in this month’s cover feature, physicists have turned to drones carrying spectrometers and even “frequency combs” – sensitive, laser-based systems that bagged a Nobel prize. Also in this issue, 100 years after “nuclear isomers” were first discovered, Philip Walker and Zsolt Podolyák pick five examples of these long-lived, excited nuclear states to show why they are so important in medical physics and beyond.

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