Limerick Pictures

Once again, my apologies for being a lousy correspondent. At some point or points I will switch tracks and be able to write to you engagingly about the new world I’m exploring here. But as of now my brain is overloaded. I’ve written my first computer programs, built a database by hand, interviewed people, held project meetings. It’s been a month and a half. I feel like my thumb has been jammed down on the fast forward button. I’d like to tell you about all that I’ve learned, but it seems less like learning and more like being swept out to sea on a tide of knowledge. I don’t think I have the authority to explain any of it yet.

This is a polite way of saying that I have no idea what I’m doing.

So meanwhile, some more pictures from my wonderful visit to Skycon at the University of Limerick. UL is a young university and so has one of the most modern and impressive campuses in the country, though it can’t compete with what we have in NUI Galway of course.

OK… What the freaking freak is that? The department of bizarre architecture? We don’t have one of those.

And I bet these buildings hardly look impressive at all when the sun isn’t shining.

Another shot of that “Living Bridge” over the mighty Shannon. Our campus has a bridge too though. Actually, our campus is crossed by a bridge.

A bit of nature for ye now. It was a lovely day for invisible spiders.

Back in the hotel after, with the gang from NUI Galway’s Computer Society. (The decent hotel where Randall Munroe was put up. We stayed in a Travelodge, a sort of footlocker for people.) What is everyone looking at with such interest – a video perhaps? Cartoons? No. Server logs. They’re using phones to view what’s happening on the club computers.

I know I’m going to like these people.

Randall Munroe in Limerick

They carry him back to their village and worship him as their god

You might expect someone who thinks so much and so deeply about mathematics and science to be socially uncomfortable with the normal humans, but Randall Munroe is an engaging and amusing speaker – both in front of a lecture theatre audience and over dinner later.

This was at Skycon’12, a really good weekend conference put on by the University of Limerick‘s computer society. Other speakers included Mark Shuttleworth, creator of Ubuntu Linux, and…

OK, how many people have I lost already? I need to remember that not everyone is immersed in Geek culture, even now. Randall Munroe is hugely famous; possibly the second most famous person I’ve met. After Colonel Sanders.

But he’s not… TV famous, for want of a better term. Not public property.

I spend much of my social life in a world where everyone but everyone knows who Randall Munroe is. That world is congruent with the other one – you’ll find XKCD fans in every country of every continent – but it is still a shadow world. You’d be forgiven for thinking that Geek culture is mainstream now, what with everyone being on Facebook and all, but really most people just hang around the gateway to the other realm.

And so he can have literally millions of fans – of which I am certainly one – yet still speak at an obscure conference in a small city, and have a quiet dinner after with friendly and only slightly overawed strangers. If you’re going to be famous, I think that may be the way to do it.

Definitely not Frank McCourt’s Limerick.

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!

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.