21 Geeky Facts You Might Not Know About Beer, Explained By Physics

The Institute of Physics is running a campaign showing how physics affects your beer. Take notes, there will be an exam in the pub on Friday.

1. Let's start with the basics: you should pour your beer into a glass that is at an angle.

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You want some bubbles, to create a head on the beer, but not too many or the beer will taste flat. So start by pouring into a glass that's tipped at a 45 degree angle to minimise foam, then finish by tipping the glass upright for the remainder of the pour. Job done!

2. When you open a bottle of beer, the air in the bottle suddenly depressurises, condensing into a tiny cloud of water vapour.

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3. The glass you drink out of affects the taste of your beer.

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The glass shape affects how much your hands warm up your beer, and the flavour of beer is affected by its temperature.

A thick glass, or one with a handle, protects your beer from the heat of your hands and keeps it cooler. Beers that taste better closer to room temperature prefer a chalice glass that the drinker can cup.

4. Did you ever notice that bubbles sink in a stout?

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But some of them are rising too. The ones in the centre rise, and this sets up a circulating current in the pint, dragging the liquid on the outside down. The bubbles are dragged down with it, so that's what you see.

5. When someone pulls you a pint, they are actually pushing the beer.

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6. Light that's bouncing inside the head on a pint is what makes it a different colour to the beer.

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7. And the size of the head on a pint decreases exponentially.

Rhett Allain / Via vimeo.com

Rhett Allain at Wired did the maths.

8. Lipstick or greasy fingers can stop a good head forming.

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Starting off with a wet glass will have the same effect.

9. Oxygen is the enemy of your beer.

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So CO₂ is added to stop it going off. Otherwise the oxygen would cause it to oxidise and go off quicker (a bit like when you leave a bottle of wine open and it goes vinegary).

10. There’s about 2.5 pints of CO2 dissolved in a pint of beer.

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11. The bumps on the bottom of your beer bottle are there to make the bottle easier to move round the factory.

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The friction between the bottle and the conveyor belt needs to be just right so that the bottles don't tip over.

12. Hitting a bottle on top with another bottle causes a shockwaves which results in silly amounts of foam.

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Here's the explanation.

13. Scientists use the same technology to monitor bubbles in beer as they do to monitor volcanoes.

NASA / JSC / Via earthobservatory.nasa.gov

14. A temperature difference of a few degrees when making beer will result in drastically different flavours and colour of the final product.

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15. Humid weather makes your beer warm up faster.

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On a very humid day in Saudi Arabia, for example, a can of beer starting at 0°C would warm by around 9 °C in five minutes (not that anyone would be drinking beer in Saudia Arabia, of course.)

16. Freezing your beer will make it stronger.

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That's how BrewDog came up with their one-time world's strongest beer Tactical Nuclear Penguin.

17. You can tell how alcoholic your beer is from how things float in it.

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The denser the beer, the less alcohol it contains. Breweries use a device called a hydrometer that floats in the beer to calculate the density of the beer and work out what percentage alcohol it contains.

18. Barley has been grown in space, meaning you could brew beer there if you really wanted to.

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And on a long duration mission to, say, Mars, with only a handful of crew, you're probably going to want to do that.

19. But if you don't have any plans to be an astronaut, you can buy beer brewed with actual moon dust.

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But only if you go to the Dogfish Head brewery in Delaware.

20. Beer could survive a nuclear apocalypse.

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During the Cold War, scientists dropped nuclear bombs on beer and soda to see how it would fare in an apocalypse. Surprisingly well, as it turns out. As long as it was at least 1270ft away from ground zero and wasn't hit by any flying debris, the beer was safe to drink.

21. And it might even be what allowed civilisation to thrive in the first place.

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By growing barely to make bread and beer people could stay in one place, creating villages that grew into towns and eventually cities.