Oct 20 2009

Twitter, rumours and physics

The twittersphere avoided making a bit of a mistake this morning. Wikileaks had obtained a new version of the BNP membership list, which they released (the BNP claim this list is a fake). Prior to release it was claimed that a peer of the realm was on the list and immediately post release that peer was named. Only it turns out it wasn’t him, someone who styled himself Lord with a very similar name was the man on the list. Fortunately the released list was detailed enough that this could be checked, someone had the wit to check before blindly repeating the name. Once they’d done this they started correcting the false rumour (in what looks like quite a vigorous manual effort). It’s worth noting here that the fact-checker appears to be a trained journalist.

But it could so easily have been very different. It could have been very difficult to establish the rumour was false, it could have been that the diligent fact checker stopped to finish his cup of tea before tweeting his correction, the rumour could have been re-tweeted by someone with many followers. All of these things could have happened but didn’t, will this be true the next time?

On the plus side, twitter rumours do appear to be traceable back to source and it’s very easy to find the individual rumour-mongers and put them right. This is certainly true for non-malicious rumourmongering (that’s to say where people have not made a special effort to propagate a rumour, nor hide their tracks).

There is a scientific link here, modelling of all sorts of networks has long been a respectable scientific field. For example, there’s Per Bak’s forest fire model and work that follows on from there. More recently there’s been work focussing more explicitly on computer networks and social networks. To a physicist Twitter represents an example of a simple system which has nodes (with ingoing and outgoing links) and messages that are propagated between the nodes. The nodes could be trees in a forest and the thing passed could be fire, or the nodes could be computers in a network with the message being network traffic; the nodes could be scientific papers with the messages citations of other papers. The physics doesn’t care about the detail of these things, it cares about a small number of parameters in the system: how many links in and out of a node? What’s the probability of a message being transmitted from one node to the next?

So there’s an interesting bit of network analysis to do here. How fast can a rumour propagate on Twitter? What fraction of people refrain from tweeting a false rumour to stop it propagating? What’s the best way to squash a false rumour?

Having watched the no doubt frenzied activities involved in squashing today’s rumour. One useful tool would be an automated rumour-quashing robot. It would search for tweets containing the rumour (probably based on a manually selected keyword) and tweet the originator with a rebuttal.

Think before you tweet!

Oct 16 2009

Confessions of a Twitter addict

Twitter is my new addiction, twitter is an elephant described by a group of blind men.

Instructions for using twitter:
1. Sign up here: www.twitter.com (It’s worth selecting a short username)
2. Follow @stephenfry
3. Start twittering like a monkey

After a while things might start to become clearer.

Twitter all depends on who you follow; I started off following a bunch of people around Ben Goldacre (@bengoldacre) (who writes the Bad Science column in the Guardian), so naturally I ended up with a load of skeptics and science journalists. I therefore assumed that twitter predominantly contained skeptics and science journalists. But that’s not true, twitter contains many groups and subgroups and they’re invisible unless you go looking for them (or more precisely, follow them).   So finding people to follow is key, if you’re not following anybody, twitter will be awfully quiet. It’s also worth remembering that by default everyone can see everything you write.

Here are a few strategies for finding people worth following:

1. Keep an ear out for the rich and famous announcing their twittery-ness – don’t expect them to say anything back to you but it does give you something to read. @Stephenfry has something like 750,000 followers, if he points to a website and says “Look at this”, a large fraction of his followers simultaneous click the link….and the website falls over. @Stephenfry then tweets “Oh bugger”.

2. Follow a hashtag and follow people you find there. You do this by searching for something like #xfactor or #electricdreams – if you follow the hashtag for a TV program whilst it’s on then you get live commentary, which may be a good or bad thing. I was introduced to this with the debate between Lord Drayson(@lorddrayson), science and technology minister, and Ben Goldacre on science journalism (#scidebate). Twitterfall is rather good for tracking a hashtag, it automatically updates a search in real-time – new results fall from the top of the screen.

3. I searched for scientists under “Find People”, birds of a feather flock together. David Bradley (@sciencebase) is compiling a list of scientist-twitterers to which you can add yourself.

4. Once you’ve found a few people, have a look to see who they’re following and who is following them, services such as twubble or MrTweet will help you do this.

5. Try out a directory service like wefollow.

So what are they up to once you follow them?

Chatterers – some people are pretty conversational.
Linkers – some people just drop loads of links, sometimes this is automated, other times it’s just what people do.
Pimpers – famous people pimp their newspaper columns and TV progs, the riff-raff like you and I pimp our blog posts. So overwhelming is this meme that I felt obliged to kick the old blog into action, in order that I would have something to pimp!
Proclaimers – some people are proclaimers, they produce a long stream of one liners. Some of them do it in the style of a historical character:

@KingAlfredRex Pærværted Skunke Signor Bærlusconi bemoanes hys Posytion as Moste Vyrtuous Manne yn Alle Ytalie… through noyse of Bangyng Head-Board.

Robots – some people aren’t people, they’re robots. Try a tweet with tea, oblong or wasp in it (prize for making any sense). I suspect a Monty Python fan wrote the @stoningbot. I’m scared to try putting two robots into a loop…
Britney and her sausage – the less said about this one the better, suffice to say if said lady starts following you best block her.

I must admit before I tried twitter I thought the 140 character limit was ridiculous (particularly since most people are not posting over SMS – which is where the limit originates). However, having used it for a bit – it’s actually really neat. How many people can bore you in 140 characters? And fitting a thought into 140 characters is an interesting exercise. Some people do seem to be able to start an argument in 140 characters (but very few) – my twitter is very civilised.

The strengths of twitter are it’s flexibility and simplicity; communities can coalesce around a hash tag or an individual very rapidly. Applications can coalesce around it’s simple messaging and following system. If you don’t like how your twitters looking, treat it like a big soft pillow – push it around until it’s comfortable.

Basic twitter functions

There are five routes to seeing tweets on your twitter homepage:
1. Home – shows the tweets of those you are following
2. @[username] – shows tweets mentioning your username (Mentions)
3. Direct messages – shows direct messages (only you can see these)
4. Favourites – shows favourites tweets
5. Search – search for tweets containing a word or phrase

When you are posting a tweet:
@[username] directs a public message at someone. They’ll see it as a mention, along with anyone following both of you. (Not realising this in the early days caused me some embarassment). If you put a character before the @ i.e. _@[name] then all your followers can see the tweet.

d @[username] sends a private message to someone (but doesn’t work if they’re not following you).

#[label] is a hashtag. Clicking on a hashtag will bring up a list of all the tweets containing the hashtag

If you like a tweet, you can retweet it, RT @[username] is the usual form for doing this although it’s just convention and doesn’t fire up any special behaviour.

With only 140 characters to play with you’re not going to want to post full length links bit.ly and other similar services squash your links down to minimum size (and allow you to compose your tweet at the same time).

If you want to break the 140 character limit then you can use twerbose, although I suspect this violates the spirit of twitter.

There are loads of twitter clients around I use hootsuite  it’s a web-based service and supports tabs so you can collect twitters and searches related to one area on one tab. To be honest, the twitter homepage does a pretty good job. If you’re interested in getting more stats on your followers then tweepular is okay.

For the data visualisation fans here’s a list of twitter visualisations, and trendsmap is fun too.

Oct 14 2009

Wordless Wednesday

Oct 09 2009

Superconductivity

This is a little post about superconductivity, lecturing and liquid nitrogen.

The lecture I remember most clearly was when I first demonstrated the Meissner effect in a superconductor. You can buy a little kit to help with this. It contains a little powerful magnet, a disk of a high temperature superconductor and a polystyrene dish. Put superconductor in dish, add liquid nitrogen to dish, wait for bubbling to subside then drop small magnet onto superconductor and this happens:

(A video is better, see here)
The little magnet just sits there, suspended above the superconductor, if you give it a prod it’ll spin around on it’s axis. It’s magic! Now the first time I did this was live in a lecture theatre in front of fifty students. I’d not had a chance to try it out in advance, and I must admit I was a bit underwhelmed by the equipment provided. So I did the tippy-out-the-liquid-nitrogen and wotnot, and my first words thereafter were “Bloody hell – it works!” – the students seemed impressed too. Much poking of the little magnet with the plastic tweezers was done, and we also splashed around the liquid nitrogen for more fun. I did the demonstration the following year, but it wasn’t the same without my genuine surprise and excitement.

Lecturing is a bit of performance (quite literally), I struggled with the format because I found it hard to get meaningful feedback from a large group of students. If you do it passionately and enthusiastically it comes across to the students, but that’s difficult to sustain for lecture after lecture. If you get it spot on, it’s brilliant but usually its just a chore (for both student and lecturer).

Just to explain a little more about superconductors: a superconductor is a material which conducts electricity perfectly – it’s resistance is zero (not just small, zero). A light bulb, an electric fire or kettle would be utterly useless with a superconducting element, the electric current would flow through it without emitting any light or heat. Heike Kamerlingh Onnes discovered superconductivity in 1911 (having first worked out how to liquify helium to cool his samples). More recently a bunch of so-called high temperature superconductors have been discovered, the weird thing is these materials are ceramics – they don’t conduct at all at room temperature and yet cool them down to liquid nitrogen temperature (-196degrees centigrade) and they conduct really well. As I’ve mentioned in earlier blog posts, superconductors are used for the making of big magnets and there are also some applications in very sensitive detectors. In principle they would be great for electrical power transmission, but the requirement to cool everything down to at least liquid nitrogen temperatures has meant they’ve not been economically viable.

Laboratory scientists take liquid nitrogen for granted but it’s an utterly alien material, like furiously boiling water but at the same time deep-bitingly cold. It hisses as it’s poured into a new vessel, wreathed in clouds of condensing water vapour. Liquid nitrogen splashed on a laboratory floor will chase dust bunnies around with distinct droplets of fiercely boiling liquid, like tiny hovercraft. The droplets vanish without a trace.

Oct 07 2009

Wordless Wednesday