Letters archive

Michael Harrison suggests that neural networks should have a "don't know" output (Letters, 30 June ). If he visits the mathematics gallery of the Science Museum in London he will find the London Hospital Survival Predictor , which I invented in 1972. It used two "classifiers" on electroencephalograph data from patients in a coma after …

Catherine Brahic asks whether we will soon use CRISPR to create children that are fitter by design, rather than by evolution, and if so whether we will have transcended the state of living things ( 30 June, p 36 ). If this comes about, surely it will be another step change in evolution, comparable to …

Brahic suggests that we may soon no longer fit NASA's criteria for life because we now use CRISPR editing techniques to modify our own genome and hence may no longer be subject to Darwinian evolution. But we have been modifying our genomes for as long as we have existed as a conscious species, simply by …

Researcher Frédéric Lechenault concludes that the stretchiness of knitting is due to the way interlocked stitches spread friction through the fabric, based on an assumption that the yarn itself doesn't stretch ( 30 June, p 19 ). Perhaps he should watch someone knit a scarf. Depending on what pattern of stitch a knitter uses, they …

Peter Wilson is enthusiastic about electric aircraft ( 30 June, p 24 ). But one problem they face is that an empty battery weighs just as much as a full one, whereas a liquid-fuelled plane gets lighter and more efficient as its tanks empty. So can we jettison empty batteries and recover them? I recall …

What Wilson fails to mention is that the heavier the plane , the more energy it takes to get from A to B because more lift is needed and there is more drag. About half the weight of a liquid-fuelled long-range flight at take-off is fuel. We need instead to develop liquid fuel that doesn't …

Clare Wilson reports doctors saying that you cannot replace their wealth of experience and "gut feeling" during consultations ( 7 July, p 25 ). But when discussion or examination of a patient isn't enough, doctors rightly send them for tests. We all dislike incursions into our expertise, but sometimes it can be more expert still …

You accompanied an article on the public acceptance of genetically modified food with a comment piece by Lesley Paterson in favour of scientists asking for public views on where to take GM food ( 7 July, p 23 ). This is superficially appealing, but problematic. Such consultations don't happen for most areas of science – …

I was interested to read about how the GM debate may turn into the gene-editing debate ( 7 July, p 22 ). Has anyone done any research asking people who are against gene-edited foods whether or not they are also against using gene editing in treatments for, say, cancer?

I was pleased by the unequivocal line you are taking concerning the possibility of a "no-deal" Brexit (Leader, 14 July ). The phrase "crash out" would be most appropriate. I hope you sustain this approach, as I fear that already we are being subtly primed by hard-liners to accept "no-deal" as a valid option. Now …