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 …

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; …

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 …

You report evidence of an earlier origin of LUCA (the last universal common ancestor of all life), around 4.2 billion years ago. If LUCA emerged then, this would give just a 300-million-year window between the formation of Earth's surface and life's origin ( 20 July, p 9 ). It seems unlikely this could have occurred …

Your article on psychological barriers to exercise only addressed one aspect of the issue. I doubt I am alone in associating exercise with fear, even when someone else is doing it. I had to take my courage in both hands to read all your articles on exercise, and by the end I had definite signs …

Gravitricity's energy-storage scheme uses a 25-tonne weight dangled in an old mine. Since a great deal of wind energy is generated offshore, we could use excess electricity to pull a large air-filled float down to the sea floor and, in times of need, use its rise to generate electricity ( 20 July, p 36 ). …

Roger Harrabin speaks of massive energy-storage projects involving weights in deep mines, but it occurred to me that all new-build houses could include some sort of double wall with an individual "falling weight" device, wound up by the output of solar panels or wind generators during daytime and allowed to gradually fall in the night, …

Aviation safety over oceans isn't solely dependent on navigational systems like GPS, which, as you report, have been subject to jamming. Aircraft carry a traffic alert and collision avoidance set-up, an independent radar-based system, to reduce collision risk. It works well for aircraft in the usual flight/cruise conditions, assuming the crew pay attention to alerts …

At the age of 78, it was very disappointing to read that the ITER fusion reactor project in France is apparently not going to be fired up in my lifetime, if ever ( 6 July, p 13 ).

The idea that middle-age lifestyle choices can influence how your brain ages is interesting. When I was 42, my husband died, leaving me with four children and debt. I went back to college, retrained for a different career, took my driving test, remortgaged and got on with life. I got a job, joined a union …