Letters archive

I was amused to read of Michael Frayn's unpromising starting materials – chalk and elderberries – for making explosives at the age of 7 (23 September, p 50). I recall similar researches on my own part at a similar age. I, at least, had paraffin as an available ingredient, but I, too, failed to make …

• Due to an editing error, our article about snake venom (30 September, p 51) stated that it is possible to receive a deadly bite from garter snakes, American racers and radiated rat snakes, all of which are kept as pets. This is not true. Even if you put your hand into those snakes' mouths, …

In his article on mathematical proofs, Marcus du Sautoy raises the issue of the acceptability to mathematicians of computer-assisted proofs: "the possibility remains that a glitch is hiding somewhere in the mass of computer code that could kill the proof" (26 August, p 41). The correctness of the proof is the issue that is usually …

In my view, the conclusion reported in your article on food fads that "you might as well not bother" to increase fibre intake to reduce your risk of colon cancer remains premature until investigators have studied the effects of long-term fibre consumption from natural foods, in amounts approximating to 100 grams per day (23 September, …

The article about biofuels unfortunately repeated uncritically some naive ideas suggesting that the interests of the global poor are served by cheap food produced on agricultural land in rich countries (23 September, p 36). The reverse is often the case, as potential exports by Third World farmers – who constitute most of the world's poor …

I was fascinated by Lee Smolin's article on the mutability of the laws of nature (23 September, p 31). He says that the question that keeps him awake nowadays is: "Is there a way to represent the laws of physics mathematically that retains the notions of the present moment and the continual unfolding of time?" …

Patrick Barry's article describes John Cramer's proposed experiment to delay one of two entangled particles by sending it on a longer journey than its twin, then forcing the delayed particle to choose wave or particle form in order to find out if the choice forced upon it controls the form of the twin particle, detected …

Burying carbon dioxide is being promoted by some sections of the coal-fired power industry as the solution to climate change. Aside from the massive technical hurdles to be overcome, one of the problems with such techniques is the limited availability of suitable geological structures in which to store the enormous quantities of CO 2 we …

I refer to your article on military robots (23 September, p 28). Is it just me, or can anyone think of an easier way to get a munition into a US base than by attaching it to a robot with an autonomous "return home" function? So, military robots might be developed by the Pentagon with …

The main thing that your report on how to be a genius missed was the other, unsuccessful side of the coin (16 September, p 40). While the genius-level achievers mentioned in the feature all had the work ethic, the inspiring tutor and so on, we didn't see how many others had the same opportunities, worked …