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進入《中英對照讀新聞》Maths cracks beer froth mystery 數學破解啤酒泡沫之謎
◎鄭寺音
Mathematicians have come up with a formula that predicts how the head on a pint of beer will change after pouring.
數學家已經提出一個公式，預測一大杯（品脫）的啤酒在倒入大酒杯後最上層會如何變化。
Their advance could shed light on why the foam on a pint of lager quickly disappears, but the froth on a pint of Guinness sticks around.
他們的研究結論可能可以解釋，為何一大杯黑啤酒的泡沫會迅速消失，但一杯Guinness啤酒的泡沫會留著的原因。
Beer foam is a cellular structure comprising networks of gas-filled bubbles separated by liquid.
啤酒泡沫是一種由氣泡組成、由液體加以分隔開來的網絡構成的分子結構。
The walls of these bubbles move as a result of surface tension. The speed at which the walls move is proportional to the curvature of the bubbles.
這些泡沫的內壁會因為表面張力而移動，內壁移動的速度，與泡沫的曲率成比例。
As a result of this movement, the bubbles merge and the structure "coarsens", meaning that the foam settles and eventually disappears.
這種移動導致泡沫互相結合，結構「變粗」，代表泡沫安定下來，最終消失。
"What happens in beer is the small bubbles shrink; the big bubbles grow," said David Srolovitz, from Yeshiva University in New York.
「啤酒的情況是小泡泡縮減，大泡泡變大，」紐約葉史瓦大學的史羅洛維茲說
"Eventually, the big bubbles pop—although they pop for slightly different reasons. On Earth, there’s gravity and the liquid that’s within the walls tends to drain out back into the beer. The walls get thinner and thinner and eventually they pop."
「最後，大泡泡破裂—雖然它們是因為稍有不同的理由破裂。地球有引力，內壁的液體會回流到啤酒內，內壁越來越薄，最終破裂。」
新聞辭典
froth︰（啤酒等的）泡沫，氣泡。如 a glass of bear with a lot of froth on it（一杯有許多泡沫的啤酒）。
shed light on︰解釋，使某事清楚明白地顯示出來。例句：As an economist, he was able to shed some light on the problem.（身為經濟學家，他可以解釋這個問題。）
