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Questions and answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. Restrict questions to scientific enquiries about everyday phenomena. The writers of published answers will receive a cheque for £25 (or US$ equivalent). Reed Business Information Ltd reserves all rights to reuse question and answer material submitted by readers in any medium or format. New Scientist retains total editorial control over the content of The Last Word. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to [email protected] or visit www.last-word.com (please include a postal address in order to receive payment for answers). For a list of all unanswered questions send an SAE to LWQlist at the above address. THE LAST WORD Chest in time In running races, the winner is the athlete whose torso crosses the line first. Hands, knees and heads don’t count. How, then, does the device that records the winning times work? In particular, how does it know which part of the body has crossed the line first? And how does it distinguish between all the athletes, some of whom must be obscured from a beam across the finishing line by their rivals? n The “beam” of the finishing line is really a camera that rapidly and repeatedly takes a picture of the plane of the finishing line. Over time, the slices of images of the finishing line are compiled into one picture and coordinated with the event clock to recreate a time-elapsed picture of the finishing line. These pictures are how the times and places of the athletes are determined. They can be odd in appearance. For example, if an athlete’s foot lands on the finish line itself, multiple photo slices give it the appearance of a ski. While the picture itself is auto- generated, the times and places are determined by a human judge. For each athlete the judge finds the position of the athlete’s chest. While this might not sound like a well-defined point, the athletes know how to contort their bodies at the last instant to make the chest cross the finish line at the earliest possible moment. Once the judge pinpoints the athlete’s chest the corresponding time of crossing the finishing line is determined from the picture. To minimise athletes blocking each other, the camera is raised and gets a bird’s-eye view of the line. I suspect there would be far more injuries from diving at the line if the hand rather than the chest were chosen to determine the winner. June Andrews San Francisco, California, US Modern remains I work as a wildlife tour guide in the Scottish Highlands so I travel widely in remote corners of the northern Highlands and islands. On two occasions in late 2009 I have come across a pile of odd objects (see photos) scattered on the ground. The first time was on a remote island in Orkney; the second was a few weeks later at an altitude of around 900 metres in the Cairngorm mountains. Had they been near a road or habitation I would probably have dismissed them as just some sort of household electronic debris, but in both cases they were miles from anywhere. The pile I found in the Cairngorms was at least a 2-hour walk from any road, track or building. They appear to have a burnt and pitted charcoal- like solid centre encased in a hard, plastic-like cover. The ones in the Cairngorms also had some small, charred battery-like cylinders with them. Can anybody suggest what they are, and why they ended up in such unexpected locations? (Continued) n The debris is from an old weather balloon. I used to see these on the Scottish mountains all the time in the 1970s. A sharp eye would spot a silver mark lying on the heather where it had landed. As a child I walked miles with my dad to collect these for proper disposal. If your reader found charred remains this was most likely on a managed grouse moor where one had landed in very long heather and could not be seen. The managers of the moor then burned the heather in rotation to improve the red grouse habitat. Such practise provides young heather for food and leaves long heather for shelter. The weather balloon would have burned in the fire, leaving hard parts such as the battery segments shown in the photos. Pete Oswald Taftshurie, Orkney, UK This week’s questions WHISTLE-STOP I recently bought a roof rack for my car and to my delight discovered it likes to whistle when my car approaches 100 kilometres per hour. But why does the whistling stop whenever I go under a bridge? Peter Morris Birmingham, UK IN A BLUE MOOD Why and how did blue become the standard colour for biro pen ink? Craig Mackie London, UK “A camera takes repeated photographs of the finishing line and compiles a single picture” Last words past and present, plus questions, at last-word.com A new collection: the usual insight, ingenuity and wit – this time with full colour photographs Available from booksellers and at newscientist.com/orangutans Why are orangutans orange?
