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As a retired pilot I was intrigued by the Pentagon's plans to recharge micro air vehicles (MAVs) from power lines (5 January, p 22) . I fear that one factor may have been overlooked. The American military has a well-known propensity to destroy absolutely everything within a wide area of a combat zone, so it …

• The vaquita ( Phocoena sinus ) is a porpoise endemic to the Gulf of California (Sea of Cortes), and not to the Gulf of Mexico, as we suggested (22/29 December 2007, p 19) . • A. C. Grayling's comment on the fate of conceptions should have read: "an estimated quarter of all pregnancies spontaneously …

Â鶹´«Ã½ readers might be aware of the new Indian car, the Tata Nano, which will sell in India for the equivalent of £1300 and has a claimed fuel consumption of 5 litres per 100 kilometres or better. The car is expected to sell by the million to India's present cycle and motorcycle users. It …

The best spellchecker is Google. It is virtually immune to the "Cupertino effect" you describe (1 December 2007, p 62) . Google has access to probably every word in all major languages and, more significantly, it can evaluate spellings in context. Type a phrase into the Google search page with one or more misspellings and …

Evolution from a single-celled ancestor to all the current forms of life requires not merely "changes in gene frequency" (8 December 2007, p 46) but the spontaneous generation of qualitatively new information coded in new genes at countless points along numerous lines of development. Simply changing gene frequency is selective breeding, not evolution. In the …

Jennifer Ouelette suggests that Marco Polo introduced yodelling to Europe from Tibet (22/29 December 2007, p 58) . But in the 1959 movie Thunder in the Sun a group of Basques from the French Pyrenees make their way to California in the 19th century. The film showed the peculiar traditions of the Basques – a …

If I understand him rightly, A. C. Grayling says that closing off areas of cities to cars might lead to urban decay because there is evidence of links between inaccessibility and decay (12 January, p 48) . But most people do not travel around central London by car at all, and access on foot or …

You report research at Harvard University finding a correlation between childhood learning difficulties and road traffic fumes (5 January, p 13) . To compound the matter, the tar used in blacktop roads could also be a source of health problems. Polycyclic aromatic hydrocarbons are usually present in these tars, as are numerous other toxic compounds, …

Mike Huckabee might appeal directly to the evangelical right wing of the US Republican Party (12 January, p 3) , but on a national scale he is way behind John McCain in the polls and it is McCain who is by far the biggest hidden threat to scientific fact and education in the US. McCain …

Your recent article about attaching cameras to animals to monitor their behaviour (19 January, p 22) got me thinking about the problem of the weight of the devices. Could this be avoided by distributing them throughout, say, a flock of birds? Perhaps one bird could carry a camera and low-power transmitter, with another carrying a …

Although your report of our work on software which seems to encourage students to focus on the wrong aspects of scientific problems (5 January, p 22) quotes our results correctly, the website headline "Physics tool makes students miss the point" yields a spin that we are afraid may make readers draw an incorrect inference. Our …

Debora MacKenzie wrote that the anti-smoking aid bupropion is banned for use by athletes "on the day of competition, but it can be used during training" (12 January, p 12) . To clarify, bupropion is not a banned substance at any time – whether during or out of competition. It has been placed on a …

Jeff Warren attributes "informal laws" to lucid dreams (22/29 December 2007, p 73) . I have often wondered to what extent the laws of physics are respected in these highly realistic dream states. The last time I had a lucid dream I inspected my image in a mirror, and found it to be inverted in …

Hugh Everett's many-worlds view of quantum mechanics has implications for the fate of the universe (24 November 2007, p 52) . Suppose there is a 90 per cent probability that within the next hour the "false vacuum" containing our universe will decay into a zero-energy ground state containing no material universe. This implies that 9 …

You imply that the misuse of science by anti-smokers is a rare and recent phenomenon (10 November 2007, p 8) . It is neither. In 1950 Richard Doll and Austin Bradford Hill published the results of a preliminary study which showed an association between smoking and lung cancer. It also showed that men who inhaled …

The views of the physicist Niels Bohr on language have a lot to answer for, not least David Peat's article about the language of physics (5 January, p 42) . If European languages really consisted only of sentences like "the cat chases the mouse", communication would indeed be impoverished. But we can produce sentences like …

I read with some surprise that for us Scandinavians the straw goat is the equivalent of Santa's reindeer (22/29 December 2007, p 38) . As a Norwegian I have no relation to said goat whatsoever. I understand from the article that it is popular in Sweden. What people believe in Denmark is not revealed. Apparently …