Letters archive

Helen Greiner's call to design practical robots really hit the nail on the head (21 January, p 20) . I was an early pioneer in autonomous human-scale robotics. My friends often ask me why I'm no longer "in the game", building walking, talking robots. I tell them it's because the world does not need humanoid …

The article on the Durban climate talks was a useful synopsis of the current state of affairs (17 December 2011, p 8) , but the diagram analysing the gap between the projected emissions of 55 gigatonnes of carbon dioxide in 2020 and the environmentally desirable goal of 44 gigatonnes suffered from a gap of its …

Commercial travel to near space in helium-filled balloons (24/31 December 2011, p 46) is to be deplored. Helium is a non-renewable commodity in demand for superconducting magnets in medical and science applications. Even if the envelope of the balloon is recovered, the gas will be lost, which cannot be justified for such a frivolous purpose …

It is fascinating to read that cognitive differences may have played a big role in modern humans seeing off Neanderthals (14 January, p 26) . I've also read that Neanderthals may not have invented sewing needles, so were unable to sew well-fitting and warm leather garments, unlike Homo sapiens . Neanderthals' neophobic attitudes would have …

Creativity is a many layered thing. Your feature on non-human art showed that a computer may compose a score (14 January, p 42) . Crucial to our appreciation, however, is the interpretation of the musician, the subtleties of their pauses, breathing, emphasis and so on. I wonder how many shades of pressure Aaron the painting …

Paul Root Wolpe asked for a single symbol to represent all of science (7 January, p 24) . Around 400 BC, Greek philosophers Leucippus and Democritus proposed that the world is made of atoms. More recently, physicist Richard Feynman suggested the atomic hypothesis when asked for a statement containing the most scientific knowledge in the …

In his letter, Steve Hibbert (7 January, p 29) asks if any present-day actresses have been active in cutting-edge research. Natalie Portman co-authored two papers. Her 1998 high school paper "A Simple Method to Demonstrate the Enzymatic Production of Hydrogen from Sugar ", written with Ian Hurley and Jonathan Woodward, was entered in the Intel …

David Comerford's letter talked of economists' reservations about The Limits to Growth (28 January, p 32). Traditional economics and The Limits to Growth reach different conclusions because they start with different assumptions. The question is, which assumptions describe reality? In Limits , the consumption of resources does not change as limits are approached, so there …

"Forbidden reactions" told of five chemical reactions that scientific orthodoxy of the day said couldn't happen ( 21 January, p 30 ). What is worrying is that terms such as "asked to leave", referring to the treatment of quasicrystal researcher Dan Shechtman, and "holy war", describing Herbert Brown's stand against non-classical ions, appear in an …

• The ruffed grouse makes a drumming noise by beating its wings while standing on a log (21 January, p 14). It does not strike the log. Ringo Starr can relax. • The DOI in the story of an artificial brain developing approximate number sense (21 January, p 9) should have been 10.1038/nn.2996.

A lottery draw, which is televised, uses balls numbered 01 to 39, from which five winning balls are selected and displayed in a row. By the magic of the producer's graphics software, they are then rearranged into ascending order from left to right, to make checking easier. One week, two of the winning balls had …