Letters archive

James Dinneen's article on the challenge of reducing our rate of energy consumption to 2000 watts encouraged me to put some numbers into a calculator( 11 February, p 36 ). Our car used 748 litres of fuel over a period of 381 days. Taking the energy value and density of diesel as 43.1 megajoules per …

The difference between averaged power usage, as imagined in the 2000-watt challenge, and peak power usage is important. It is the latter value that grids must be designed to supply, with power stations ready to fire up to meet it, especially when renewable inputs are lacking. These stations are usually gas fired, and this makes …

Dinneen switched from drying his clothes in a powered dryer to hanging them indoors. Does this really use less energy? Surely, the energy to evaporate the water is the same regardless. Of course, the best thing would be to hang clothes outside, but, where this isn't an option, the evaporation would cool a building and …

One of the most significant long-term contributions people can make to cutting carbon emissions and energy use is to have fewer children.

There is a relatively simple solution to the question of dark matter – the unseen mass thought to be exerting an additional gravitational effect on galaxies( 11 February, p 46 ). In his book The Elegant Universe: Superstrings, hidden dimensions, and the quest for the ultimate theory , Brian Greene explains that string theory postulates …

Reader Chris Hall wonders what Darwinian forces might drive European eels to undertake a 12,000-kilometre journey across the Atlantic and back to breed. This could be an adaptation to the formation of the ocean about 150 million years ago via slow spreading of tectonic plates( Letters, 11 February ). Perhaps eel ancestors had breeding grounds …

You say that "for much of recent human history, nature has been regarded as mere property... to be exploited". Many cultures don't see nature that way at all, and I suggest it is the Judaeo-Christian idea that we have "dominion over nature" that is the main problem( 11 February, p 26 ).

Your feature on immunity states that the immune system wastes its resources attacking the cytomegalovirus pathogen, which persists nonetheless. If this virus rings our immune alarm bell so much, you might assume that the immune system would have evolved to kill it off( 4 February, p 43 ). Could this be like countries holding war …

You report that mammals such as foxes have been infected by the current bird flu virus. This has been attributed to scavenging of the carcasses of infected birds( 11 February, p 8 ). It seems to me only a matter of time before other wild mammals – especially rats, as scavengers, and squirrels, as raiders …

You report that mongooses and warthogs display "the only known mammal-mammal mutualism in the world". That does seem to be true of land-based mammals( 4 February, p 44 ). I wonder if there are valid examples for marine mammals, such as seals leaving their young pups to be watched over in sea lion nurseries, or …

Andrew Rogoyski works at the University of Surrey, UK ( 4 February, p 25 )