When beer is poured into a 500-millilitre glass, somewhere between 200,000 and 2 million bubbles rise to the surface to form the foamy head.
This estimate was made by Gérard Liger-Belair and Clara Cilindre at the University of Reims Champagne-Ardenne in France, who calculated the number of tiny bubbles that form before a lager goes flat.
The researchers first measured the amount of carbon dioxide dissolved in 250 millilitres of lager after it was …