Letters archive

You are right to highlight the importance of heat storage as a way to use surplus renewable electricity. A big but under-appreciated resource on this front is the hot water tank. We have about 9 million in UK homes, typically supplied from a gas boiler, with a 3-kilowatt immersion heater backup ( Leader, 20 July …

Some things don't change. Our ancient ancestors valued caves as a haven from the weather and wild animals. Now, we are considering using caverns on the moon as protection from space "weather". Perhaps we should think about installing a copy of the Lascaux cave paintings in the first lunar cavern we use for habitation ( …

Having watched the first two A Quiet Place films, and reading Douglas Vakoch's lament about the irrational fears raised by the portrayal of scary extraterrestrials in the third film, I wonder if I am alone in believing these blind movie aliens aren't even remotely likely? Sharp-eared enough to hear a picture frame smash a mile …

The underlying debate is whether it is a good idea to send signals to try to reach intelligent aliens. The worry is there is no global entity that polices such transmissions and, even if there were, it would be impossible to enforce. But I agree with Vakoch that it doesn't matter because aliens advanced enough …

As a scientist, I prefer to think in terms of components, causality and processes. It would be good to know more about these when it comes to ultra-processed foods ( 13 July, p 10 ). There are many questions. Which additives might degrade the mucus lining of my gut, leaving me at risk of bowel …

Bringing back the dodo might have commercial implications because it was apparently tasty to eat. I can imagine meat producers being interested in an edible bird twice the size of a turkey, especially if its growth or reproduction rates could be tweaked ( 15 June, p 40 ).

In your look at the possibility of extra dimensions, Georges Obied says: "There's no reason why it has to be three. It could have been two; it could have been four or 10 ( 13 July, p 32 )." I wonder whether we can look to the anthropic principle as to why we have at …

Andrew Whiteley notes that the idea of our cosmic insignificance involves "equating physical size with significance", which he rightly decries as absurd. A similar point was made by the polymath Frank Ramsey: "I don't feel the least humble before the vastness of the heavens. The stars may be large, but they cannot think or love; …

As I see it, to replace a lot of fossil fuel use requires a chemical that would react, for example with water, to produce hydrogen on demand. A driver could go to a fuel station with a spent pack of this chemical, buy a new one and fit it in place and drive off in …

Geshuang Chen's photo shows an optical corona ( 13 July, p 25 ). To gauge the ideal bowl size for spent pistachio shells, they were modelled as hollow half-spheres with 73 per cent of the packing density of the whole nuts in shells ( 13 July, p 9 ). Boston Dynamics's robots are banned from …