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The concept of "virtual water" (8 November, p 8) seems applicable to all resource use. China can't dig up enough coal, so it relies on "virtual coal"; France relies on "virtual uranium"; and the US on "virtual carbon". I wonder what the true emissions of the US would be if we were to include the …

Would it really be such a bad thing for space tourism to stall on the launch pad (1 November, p 5) ? It borders on the obscene that the world allows private space flight when everyone with an ounce of sense knows now is the time to cut back on unnecessary carbon dioxide production. Exhilarating …

Holly Preston asks why Â鶹´«Ã½ is not published solely online (1 November, p 20) . Answer: it folds into my jacket pocket and goes absolutely everywhere with me until finished – breakfast, bathroom, morning tea and lunch in the cabin of my truck, on the tram, waiting in queues, or just relaxing in an …

Amanda Gefter's article on the "cultural war" over the brain significantly misrepresents non-materialist neuroscience (25 October, p 46) and does a disservice to your readers. Most participants in the 11 September symposium "Beyond the Mind-Body Problem: New Paradigms in the Science of Consciousness" at the United Nations were medical doctors or neuroscientists who work with …

The day before I saw Amanda Gefter's article on the mind/body controversy (25 October, p 46) , I presented a first-year general philosophy lecture covering the "thinking matter controversy" of the 17th and 18th centuries. In 1651, Thomas Hobbes's book Leviathan stirred up a hornets' nest with his claim that minds are material. He provoked …

The paper "Cross-cultural analysis of students with exceptional talent in mathematical problem solving" in Notices of the American Mathematical Society to which A. C. Grayling refers (25 October, p 48) was written by three male mathematics professors and Janet Mertz, an oncology professor. It is a well-intended and thorough piece of research but, as always …

Clive Semmens is right to criticise (1 November, p 21) Tony Budd's calculation of the risk of a "once in 100 years" event occurring within 60 years (18 October, p 20) . But he falls into the same trap himself, ignoring the odds of a building blowing down more than once in the same year. …

If it is truly possible that after watching a lot of black-and-white TV programmes you can dream in black and white (25 October, p 15) , will watching a widescreen TV make you dream in 16:9 aspect ratio, rather than old-fashioned 4:3? Will we soon dream of menus offering chapter selection and extras? I rather …

Alex Pentland's work on "honest signals" is extremely interesting, but there is one important issue in the dialectic between them and the use of explicit reason, deliberation and forethought, that Mark Buchanan's review did not make clear (25 October, p 44) . It is possible to view "social cues" and explicit statements as two separate …

• We quoted views on civilian space flight safety held by Gérardine Goh, who is legal counsel with the German Aerospace Centre and would like us to make clear that these views are entirely her own and are not necessarily shared by the organisation (1 November, p 24) . She, with colleagues in the International …

T. Robertson rightly highlights our unreasonable focus on renewable power and neglect of renewable heat (1 November, p 20) . But his proposed solution, running wind turbines for heat at very low wind speeds, will not help. Turbines may have a tough time synchronising to the grid at low speed, but this is not a …

Richard Elwes writes, "But what is it exactly about the conjurer's knot that means it can be pulled apart just like that, but the shoelace cannot?" (25 October, p 32) . This immediately brought to mind the stunning demonstration that my son gave, aged 6, of his own method for untying his double-knotted shoelaces. He …

Feedback refers to "proper terminology" in the naming of Bigfoot and goes on to refer to the name Anthropoidipes ameriborealis as being derived from Latin (8 November) . It is of course derived from Greek, as are many so-called Latin names. The key words, transliterated, are anthropos (man), eidos (form), pous or podos (foot) and …

Mark Buchanan writes about how speculative information causes people to act in stock markets (1 November, p 15) . Last summer, the satirical newspaper The Onion ran a story headlined "Stock market rises ten points on rumours stock market would rise ten points". Rings true, doesn't it? The editor writes: • Even better, we find …

As an engineer who values psychologies' tools, I was delighted to read Dorothy Rowes discussing whether psychology is science (November, p 18) . I recall one psychologist being asked to find out whether vibration was a problem in helicopters. He designed a perfectly balanced experiment comparing several frequencies of very severe vibration with a control …

Congratulations to Devin Powell for his interesting interview with "hypermiler" Jack Powell (25 October, p 42) . It is a subject of which we will become more aware and which we will all have to learn and practice. However, the interview only went part of the way. A major cause of increased fuel consumer is …