Letters archive

One of the main problems with so much health advice, including that based on BMI, is that it is too absolute, too definite ( 10 September, p 28 ). Advice on body weight, the recommended number of alcoholic drinks, the number of steps to walk and so on is rarely given as a range. Why …

Consuming fewer calories than are burned each day will cause weight loss. Unfortunately, too many people eat more than they need, and excess food production has major environmental impacts. Perhaps there is merit in an environmental tax that could deter this? That will motivate the curbing of appetites.

Alec Williams fears that microbes genetically engineered to eat plastic waste might come to consume useful plastics ( Letters, 20 August ). This echoes the 1970s novel Mutant 59: The Plastic Eaters . The risk is all too real, but the catastrophe might be slowed by the fact that there are many different types of …

In our look at remastered NASA images ( 10 September, p 30 ), Rusty Schweickart was in a photo of the Apollo 9 mission and the Apollo 8 astronaut was Bill Anders.

Sending people to the moon always seemed misguided ( 17 September, p 38 ). Space agencies could have flooded the solar system with hundreds of probes, rather than operating expensive crewed missions to space that make only narrow discoveries. For example, there are seven other substantial planetary atmospheres that should be utterly surrounded by weather …

It is beyond belief that we are talking of sending humans back to the moon. Have we forgotten the general loss of interest in 1972? There is now increased awareness of the dilapidated state of Earth, the huge cost of sustaining settlers on other celestial bodies and the fact that returns on such huge investments …

I propose the use of a "mooncrete", comprising a mixture of lunar regolith – or moon dust – water and hydrogel, as a material from which to build a lunar base. Moon dust is notoriously gritty stuff, composed of microscopic fragments of pulverised rock. The function of the hydrogel would be to lock those spiky …

"Come on in, the water's cold" briefly raised the issue of water quality for anyone swimming wild, but needed to go further ( 17 September, p 25 ). A report by UK group Surfers Against Sewage in May included a survey of 2000 people that found over half of those who went wild swimming last …

Your graph showed there have been more deaths than usual in England and Wales up to 5 August ( 10 September, p 14 ). The figures before 15 April were consistently low, and since then have been consistently high. My own analysis suggests that this has continued. You proposed some reasons, such as issues in …

The case for "longtermism" – caring about future generations and the environment – wouldn't need to be made if we raised all children to accept they belong to an interdependent species that is part of a global biosphere with a shared, billions-of-years-old lineage connected through DNA – and aren't, as humans, somehow chosen or special …