Â鶹´«Ã½

HERE’S the good news: scientists at Harvard University have created a beer
that retains its head for several hours. The bad news is that you have to
dissolve hexafluoroethane (C₂F₆) in your beer, which would not
please real-ale enthusiasts. “It’s not harmful or anything,” insists Sascha
Hilgenfeldt, now at the University of Twente in the Netherlands, although it is
a potent greenhouse gas.

As beer drinkers know, the head eventually collapses as the bubbles in it
burst, but Hilgenfeldt and colleagues Stephan Koehler and Howard Stone wanted to
understand why this happens. They reckoned that when the…