Thursday, August 28, 2008

sausages. Esther. Esther. sausages.

You know when you cut an aubergine in half and it has the word "Allah" written across the middle of it? Or those cock-shaped carrots that people used to send in to That's Life? Or any number of similar occurrences involving eggs, beans, melons, tomatoes, chapatis, you name it. What you have to conclude as you look at this series of pictures of random sliced fruit and vegetables is one of the following:

  • it's a bleedin' miracle and God (of one denomination or another) has decided to manifest himself by hiding in a tomato and hoping that it gets cut in the correct orientation (or ensuring that it does by exerting some spooky influence) to reveal some gnomic non-sequiturs, rather than something a bit more obvious and reliable like, say, turning up in your kitchen with a deafening blast of celestial trumpetry and having a nice sit down and a cup of tea with you and really Thrashing The Whole Thing Out once and for all.

  • what we're witnessing here is a fascinating example of a phenomenon called pareidolia, whereby the hyper-evolved human brain insists on resolving stuff into patterns that fit with its preconceptions of the world, even when the things being observed are, in reality, entirely random jumbles of stuff.

Needless to say I find the second explanation more plausible. Another good example is the "face" photographed in the Cydonia region of Mars by the Viking orbiters. Despite many more detailed photographs being taken from a variety of angles, all of which reveal that it's just some rocks that the sunlight happened to be falling on at the correct angle when the original images were captured, some people still cling to the notion that it's some sort of alien observatory or some such nuttiness. Faces seem to be a bit of a theme, for reasons that aren't too difficult to work out if you think about why these pattern-recognition abilities must have evolved: here's another one magically imprinted into the turf at Selhurst Park. And then there's the ones found in the smoke from the World Trade Centre on 9/11, or in a nuclear mushroom cloud. Some people take photos of ordinary clouds, too, for reasons best known to themselves.

More generally, any attempt to explain life, the cosmos, belly-button fluff, etc. by resorting to some notion of an external agency directing proceedings is committing the same error. No prizes for guessing the sort of thing I'm referring to here.

But I'm not here to talk about religion. No, I'm here to talk about the Olympics. A week late and via, I'll grant you, something of a roundabout route, but stay with me.

One of the things that always fascinates me about the Olympics is the photo-finish images that they occasionally show after the shorter sprints. Here's an example:

The pareidolia connection is as follows: it's almost impossible for the human brain not to interpret these images as being snapshots of the entire field of runners at the moment the race ended, i.e. as the winning athlete crossed the line, whereas in fact they are a montage of hundreds of individual narrow "slit" images of the finishing line itself, with time passing as you scan from right to left across the image. This is why the "track" always looks a bit weird in the images; it's just a tiny image of the finishing line itself "smeared" out over the whole strip.

Certain things look a bit weird; the feet tend (with some exceptions I'll come to in a minute) to look very small in comparison to the rest of the legs and body, and there's some slightly strange curvature of the shins going on, particularly for those runners who happened to be leading with a knee when they crossed the line. A couple of moments thought about the mechanics of snapping a constant series of images of the same spot reveals why this happens; basically bits of body travelling fast will be disproportionately narrow in the finished image and, conversely, slow-moving things will be disproportionately wide.

This doesn't destroy the illusion, but things start to get a bit weird when one of the competitors happens to tread on the finishing line in the act of crossing it. Then you get a phenomenon I've heard described colloquially as "ski foot", and you can see why:

It's all down to the complex mechanics of running - your head might be doing a constant 20 miles an hour, but if you consider the speed of each individual foot relative to your head's speed things get a bit more complicated. There's less chance of things ending up looking quite that weird when you're on wheels, although there's something a bit crazy going on with the spokes in the bicycle photo here. Again, if you think about the speed of any given spoke-hole on the wheel-rim relative to the (constant) speed of the wheel hub you'll see why this happens.

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