Letters archive

You tell the life story of a water molecule from a comet to the present day far too simply ( 14 November, p 31 ). There is in fact no such thing as the history of a single water molecule. We know from quantum mechanics that every time two water molecules collide in the ocean …

• A quantum mechanical view might even claim the world divides at each collision, in which case we are back to one story for the water molecule. We decided to avoid that minefield and stuck to a purely classical description.

Soils are under threat ( 10 October, p 43 ), but most farmers recognise that they are their most valuable asset and in Western Australia we take steps to keep our soils in balance. These measures include " knife point " technology to place seeds with minimal soil disturbance, retaining unused parts of harvested crops …

Great! I would feel safer if I was diagnosed by a pigeon... not a specialist... Sylvie Tapp is not entirely reassured at pigeons being taught to diagnose breast cancer on X-rays ( 21 November, p 12 ) .

There has been a lot of hype about quantum computing over the years, including claims that quantum cryptography will offer better security ( 17 October, p 10 ). This comes from a fundamental misunderstanding of how cryptography works. Our current cryptographic algorithms are already strong enough. The main weaknesses in computer system security come from …

Given the potential for a catastrophic rise in sea levels in the next 20 years if the West Antarctic ice sheet collapses ( 17 October, p 8 ), surely the UK government should be seeking to decommission coastal nuclear power stations rather than building more? Horsham, West Sussex, UK

Your Leader articles make the case for not reducing national science budgets ( 14 November, p 5 ). But it is a poor case if considered as a stand-alone issue. Science is about taking things apart to understand them; and design is about putting them back together to make a useful object. Science serves no …

I was inspired by your interview with face transplant recipient Carmen Blandin Tarleton ( 31 October, p 28 ). It offers a real example of determination to make the best of appalling events. Well done on printing this challenging article. I have tremendous admiration for Blandin Tarleton. Cambridge, UK

I note that side effects of deep brain stimulation therapy to treat Parkinson's include impulse control disorders such as excessive gambling and hypersexuality ( 24 October, p 38 ). These symptoms are similar to side effects reported for the main dopamine analogue drugs. Is it possible that this therapy causes the brain to release dopamine, …

I fully understand Jeff Hecht's call for caution over crewed space missions that might contaminate Mars with terrestrial microbes ( 7 November, p 26 ). However, although a robotic sample-return mission would help to avoid this particular problem, won't it just create another? Wouldn't it still run the risk of contaminating Earth with microbes from …

Donald McCoy interprets the Homo naledi finds deep inside a cave system as implying early mastery of fire, to light the way (Letters, 31 October ). A simpler explanation might come from a few people, blind from early in life, learning to navigate by echolocation. A Wikipedia entry reports one person demonstrating his skill in …

A basic income for all seems to be a widely assumed scenario for the future, according to Laura Smith ( 3 October, p 28 ), and Anil Ananthaswamy in his review of The Master Algorithm ( 31 October, p 44 ). I don't see much about darker futures which seem at least as likely. In …

Your recent article about the ability to take a snapshot of part of the web and access it as a "web in a box" away from any internet connections ( 26 September, p 22 ) took me back to 1997 in Pakistan. The British Council's plans to celebrate the 50th anniversary of independence were well …

Bill Corner suggests that discovering the typical duration of mammalian urination may not just be worthy of an Ig Nobel prize but actually a useful diagnostic tool for men with prostate problems (Letters, 31 October ). This sounds eminently simple and sensible, so I'm planning a smartphone app and associated gadget (on the lines of …

• That stings: the water corals inhabit is more acidic than it was, but is still alkaline ( 14 November, p 17 ).