THE BUBBLE CHAMBER

particle tracks in a bubble chamber

I was trying to do something difficult earlier. I was trying to fit together five pieces of evidence in a way that made logical sense, but was totally different to the thing I thought was the most obvious conclusion.

You see this kind of thing all the time in those lateral-thinking puzzles. Here's a classic example:

Andy and Tim are professional golfers. One day they're out playing a match. The sun is shining, the grass is green, and away in the distance, lazy cotton-wool clouds are hanging perfectly still upon the horizon. The score-card, for those who take note of such things, is currently showing Tim: 15, Andy: 30.  In two shots' time though, Andy has won the game. How?

While you're puzzling over that, I'm going to talk about CSI and bubble chambers. A bubble chamber is an old-fashioned device, filled with supercooled liquid that was used to detect the activity of subatomic particles. As they zip through the bubble chamber, they leave a trail behind. Atomic physicists used to use bubble chambers to work out what had happened in a particle collision. If the tracks went off one way towards a large magnet, say, they could determine a particle was being diverted and must be somehow magnetically charged. If it took a straight line through the magnets or stopped or curled round completely on itself, it must be a different type of particle altogether.

Bubble chambers (like the cloud chambers and wire chambers that followed them) told a story about an event that was impossible to witness first-hand. Scientists pored over the elegant trace-pictures, forensically examining the evidence left behind so that they could reach a conclusion about what had happened.

That's what they did in CSI too - although far less plausibly. There, the larger than life forensic scientists gradually laser in on an impossibly detailed result from the smallest pieces of physical evidence left at the crime scene: a corner of a piece of paper from a notebook made of paper from one rare species of pine tree, a grainy photograph that can somehow be enhanced to show an identity badge, a UV footprint, a screw from a pair of spectacles, ad nauseum. And they're almost always exactly correct these pseudo-science-nerds, not to mention unfeasibly good-looking.

I wanted to try a bit of 'devil's advocacy' with myself and my five exhibits. I had almost certainly made some assumptions about them, locked them together without really thinking about it and had fashioned a hypothesis quite quickly.

Well, the trouble is that if you have a hypothesis, it's incredibly easy to find more pieces of the puzzle that back it up - what if you could rationally pose an alternative that matches the same set of facts? Even if you don't like that backup theory, even if it frightens you and you don't want to think about it, you have at least got to believe that it's possible, surely?

Here's another example. I'm thinking of an animal. It has a long neck, spindly legs, it eats from treetops and it lives in Africa. Now, you're probably on to me: That Matt Stubbs, you say to yourself with a knowing smile, he's a sneaky old so-and-so... and you've already ruled out the giraffe. Good for you. It's a heron, but you get my point. Sometimes you can draw completely the wrong conclusion from the information you're given, based on your assumption.

This is quite a unique thing that we do as human beings. A difference engine - a processor like a computer makes no assumptions from the bottom up. It works the other way round, starting with everything possible and gradually rules out only what logic dictates given the evidence. The idea of ruling out a possibility because it is ridiculous, makes no sense to a computer. Or, as Sherlock Holmes so eloquently and intelligently puts it, whatever remains, however improbable, must be the truth.

I couldn't do it. I couldn't find my alternative theory for my five pieces of evidence. I recognise though that it's a skill I'd like to be better at. The facts just painted far too strong a picture - which might actually be the only possible conclusion (and therefore the Holmesian truth) but I was a bit annoyed that I couldn't come up with at least a much more fanciful but less likely solution.

Right there in that annoyance is my problem I think: the creative part of my brain, the bit that likes fiction and art and music and stories, is so often at war with the other side which observes, analyses and processes everything as though the world is a giant problem that always has to be solved. My brain itself is a kind of bubble chamber. Some thoughts bend round in circles with all the fanciful imagination  my 36 year old head can dream up; others just power straight on through, unaffected by my built-in opinions, desires and prejudices.

But the world isn't just a puzzle that's there to be figured out. It's there to be enjoyed. That's what looking around at this beautiful world tells me, with its amazing people and incredible potential. Ah but perhaps you have another theory about that, based on your observation of this self-same crazy old world... That's more than OK.



By the way, if you haven't worked it out yet, Andy and Tim are playing tennis.