Categories
Humour

The Sinking Guinness Bubble – Explained!

Guinness drinkers are puzzled about something. OK, after a few they’re puzzled about many things, but the one that gets you even before you start drinking the black stuff is that the bubbles in it appear to rise… downwards. This is not the standard behaviour of bubbles.

You might think that this has something to do with the unusual, possibly supernatural, properties of the famous Irish beer. But no. Scientists have finally torn their attention away from trivialities to explain exactly what is going on here, and it has less to do with the liquid itself than with the glass. Not the special Guinness “tulip” either, but any beer glass just so long as it has the typical tapering shape.

You can read the actual scientific paper here (PDF) if you don’t mind looking at maths, or MIT’s excellent non-technical account. But if you want a loose and more inaccurate explanation which has the merit of being simple enough to tell someone in the pub while they wait for their pint to settle, read on!

GuinnessPint
Other Irish stouts are also available

Like other beers or fizzy drinks, bubbles form in stout as gas forced in under pressure escapes after the pressure is released. They’re significantly less dense than the liquid of course, and therefore float to the surface – exerting a little drag on the liquid as they do. Now that drag would have no effect in a straight-sided container. All the liquid would feel an equal upward pull, so it would be in balance and none of it could move. But in the slope-sided glass things are different.

This is the crucial bit: There are always fewer bubbles directly above the sloped sides than there are directly above the flat bottom. Therefore there is less upward pull near the sides, more in the centre. This creates an imbalance – the centre goes up, and the liquid at the sides is pulled downwards to take its place at the bottom of the glass. Similar to the convection that occurs when you heat fluids, a “rolling” motion is set up.

Bubbles still want to go up at the sides of course, but the liquid is being pulled down faster than they can rise through it. The net result therefore is that they are visibly dragged downwards. And as we know Guinness is pretty opaque stuff, so though there are actually far more upward-moving bubbles at the centre, we only see the downward-moving ones just inside the wall.

The solution is simple and convincing then: The bubbles at the outside sink because of a circulating motion caused by the bubbles on the inside rising. Next perhaps mathematicians can explain why people drink the stuff when it tastes like wet cardboard.

Categories
Cosmography

Eggs At Eleven

Praise me, for I labour to advance the breakfast!

Of all things today, a recipe.

Eggs At Eleven

– An ideal breakfast for a day off –

Ingredients: Butter, milk, mushrooms, eggs, ham, bread for toast.
Time: About 15 minutes.
Serves: One to two.

  • Take a small saucepan and gently melt a largish knob of butter.
  • Add milk to cover bottom to about 1cm (½”) and, stirring all the while, bring to a slow simmer.
  • Throw in a little pepper and salt if you want.
  • Break up and drop in about five or six mushrooms.
  • Simmer mushrooms in the milk for a few minutes, being sure not to let it boil.
  • Chop four or five slices of ham up small and stir in.
  • Gently break in two or three eggs, without bursting the yolks if you can.
  • Now would be a good time to put your toast on.
  • When the white has mostly turned white, turn the heat down very low and stir in the egg yolks.
  • Continue to cook, stirring very frequently, until the egg looks almost done.
  • Take off heat and stir some more, eggs will continue to set.
  • Butter toast and cut into bite-size pieces. Put on plate.
  • Dump the good stuff on top.
  • Pour some water in the pan. You won’t regret that later.
  • Serve, preferably in bed, preferably to someone you like.
Categories
Humour Politics

Fruit Fabrics And The Austerity Agenda

You’ll regret it!

Well I hope not of course. I hope I was wrong, and the greater cuts we’re now committed to don’t further hurt the poor and stall the economy. But… It’s hard to see how they won’t.

Too late I know, but it’s worth listening to Paul Krugman‘s argument that austerity is being cheered on by people with an agenda. Said agenda being, to free the rich from the burden of the poor. Some of you will have seen him nail the point on Jeremy Paxman’s BBC show last Wednesday. Though clearly, not enough of you.

Somehow, the mayhem wreaked by unfettered capitalism in the last decade or so gets turned into an excuse to destroy the welfare state. What is the logical justification for that? Because they can, apparently.

All right, enough of the sad. Today started dull but became amazingly hot. I found myself without suitable attire, so I bought some shorts in TK Maxx. I usually try to just buy from charity shops, but there were none nearby and this seemed the next best thing.

I love the label. Whoever wrote this is bored with their job and spends the day trying to sneak in fruit and veg references. Look:

  • “Dries faster due to the higher proportion of polyester yams.”
  • “Is fabric washed and peached for extra softness and comfort.”

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