Letters archive

Jessica Marshall examines two alternative views of sadness: that it is a disorder to be treated, or an essential part of human function (17 January, p 36) . There is a third view: that it is like physical pain – indicating an underlying problem that needs to be addressed. If the problem is addressed, it …

James Lovelock's acceptance that 90 per cent of Earth's human population could perish is on a level with accepting events such as the Holocaust as minor incidents of history that will be forgotten in the course of time (24 January, p 30) . This may be true at some point, but it was not the …

Robert Kunzig and Wallace Broecker give an interesting account of technologies for scrubbing C0 2 from the air (10 January, p 34) , but they duck the problem of what to do with the captured CO 2 . It is theoretically possible to react it with steam or hydrogen to make liquid fuel, but I …

I found Michael Bond's claims that individuals are unwittingly infected by social epidemics alarming (3 January, p 24) . That individual behaviour is influenced by social networks is beyond dispute: recall the hope and optimism following Barack Obama's inauguration. This emotional response was, however, undeniably generated by the long-standing social and economic dishevelment preceding the …

The mind-body problem is not, as Owen Flanagan says, "about where the mind is located" (17 January, p 42) . It is about "mind" and "consciousness" being words flung about without much thought, despite 200 years of discussion by philosophers without any agreement as to what they mean. There can be no solutions until scientists …

It's good to see Richard Hammond backing the long-standing efforts to get more youngsters to look at science as a career prospect (3 January, p 14) . Many years' experience tells me, however, that simply keeping kids "bouncing along and excited" is not enough. From a young age kids love the entertainment and stimulation that …

Eduardo Almeida and his NASA team have ignored a fundamental principle in their interpretation of the data for rate of regrowth of tails in the newt Pleurodeles waltl (3 January 2009, p 12) . The newts use their tails for balance, so a longer, stronger tail is an advantage in a higher gravitational field. A …

As a teacher I fully agree with A. C. Grayling that the web can be a wonderful source of educational information (17 January, p 44) . Many of my teaching resources are derived from it. He is also right to point out its potential unreliability: I often have to remind my students to discriminate between …

So "botanists are rarely as idiosyncratic" as Godfrey Sykes, who in 1922 named a Mexican succulent after Lewis Carrol's Boojum (20/27 December 2008, p 63) . I offer you: Hebejeebie , a genus close to Hebe in the family Plantaginaceae, described by Michael Heads in 2003; Aquilegia flabellata nana pumila alba "Rama Lama Ding Dong …

• We said the "Martin Jetpack" was powered by two turbojet engines (24 January, p 44) . It is actually powered by a two-stroke petrol engine

Jessica Marshall reports Jerome Wakefield's assumption that sadness must have some sort of useful evolutionary purpose, because it is entrenched in our biology (17 January, p 36) . This is incorrect for a number of reasons. First, every human being is walking around with a time-bomb in our system called the appendix. This organ has …

Not only do kangaroos emit fewer greenhouse gases than cattle (20/27 December 2008, p 48) but, like other native fauna, their padded feet do far less damage to fragile Australian topsoils than the hooves of introduced species. Furthermore, kangaroo is healthier than beef or lamb and just as tasty at a fraction of the price …

Peter Aldhous's discussion of some of the techniques used to attempt to replicate the sense of touch in a prosthetic arm (24 January, p 15) interested me very much. When I was fitted with my first prosthetic arm (below the right elbow) 47 years ago, I immediately realised that I could "feel" whenever the split …

I am happy to be able to answer Tim Douglas's question about domestic heat pumps (17 January, p 16) . We have in our timber-frame, timber-clad house in the glen of Aherlow in Ireland exactly the system that he craves. When air is extracted from bathrooms, fresh air enters through a heat exchanger appropriately placed …

Two web letters point out that the methane animals produce is made from carbon that had earlier been carbon dioxide in the air (21 January) . But that is quite unimportant, because the greenhouse effect of a molecule of methane is much greater than that of a molecule of CO 2 . Even over a …