There are two things we here at Gizmodo love unabashedly: science and beer. So, when we saw that the gang at the UK's Institute of Physics had launched a site about the physics of beer, we just had to invite them to come for a chat.
We've got Henry Lau and Rik Sargent (pictured above) of Physics.org's Cheers Physics ready to answer your questions on the science of beer in the discussion below. They've been kind enough to take a quick break from an ongoing beer observation experiment (i.e. their annual holiday party), so ask 'em some good ones!
It's the weekend, you've made it through the long week, and it's time for Happy Hour, Gizmodo's booze column. A cocktail shaker full of innovation, science, and alcohol. What is the square root of wasted?
To get the ball rolling, we asked the guys to clear up a few things we've always wondered as we've stared deep into our pints.
Bubbles of carbon dioxide in beer will only form on irregularities, either tiny scratches on the glass or on specks of dust. If you look at a pint of beer you can normally see the bubbles rising in a constant stream from fixed points in the glass, known as nucleation points.
The type of glass your beer is served in really does affect the enjoyment of your beer! Some glasses—like a thinner pilsner-style glass-are great for naturally fizzier beers. They will have less liquid in contact with the bottom of the glass, causing a smaller head. Bubbles are also important for releasing the beers' aromas. When bubbles in the head burst, they spray a miniscule amount of liquid into the air, reaching your nose and tickling your sense of smell with delightful bouquets. To accentuate this, glasses with a tapered head concentrate the aroma and force the drinker's nose closer to the beer.
It might be hard to believe your eyes, but the bubbles in your pint of stout really are falling. But everyone knows that bubbles rise to the surface. So what's going on?
As your pint of stout settles, the bubbles in the center of the glass, where you can't see them, are rising to the surface. But at the same time, the bubbles touching the wall of the glass experience some drag, which prevents them from floating upwards.
The head is created by bubbles of gas, often carbon dioxide or nitrogen, that are released as your pint is being pulled. These bubbles are coated with a strong skin of proteins—these originate from the malted barley used during the brewing process, and they help the bubbles form a stable foam. But when fats or detergents come into contact with the foam, they can literally punch holes in the protein skin, weakening and destabilising the bubbles and destroying the head.
So, lipstick has the fats required to destroy the foam. The same thing happens when the beer meets other fats on your lips—from a bite of chips or nuts, the natural oils in a moustache—these all diminish the head of a beer.