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Microgreens may have a high density of nutrients and vitamins, but does the body absorb them all? Maybe the extras end up in the waste stream. It would be good to know how their absorption compares with that of "normal" diced raw carrots, for instance ( 14 October, p 36 ).

Your article reports research about nuts and raisins "dancing" in carbonated liquids. I taught school students to observe this phenomenon in the 1980s – I believe I found the experiment in the publications of the Nuffield Science Project ( 7 October, p 17 ). Your account of what happens doesn't mention the fact that when …

James Wong casts his habitual common sense on the issue of native and non-native garden plants. Yes, "alien" plants can be a disaster in unique ecosystems like the South African fynbos, but the UK's sparse flora has only 1625 native species compared with 1798 aliens established as unthreatening wildflowers ( 30 September, p 44 ). …

I was a bit shocked to read Raymond Hickey's dismissal of the circle-writing by aliens that visit Earth in the movie Arrival . He says no animal "would use such a short-supply resource as their ink for primary communication". Why assume that it was even their own ink? Or maybe their own ink isn't, for …

Hayaatun Sillem is correct in her assessment of the shortage of graduates in engineering ( 28 October, p 21 ). The lack of women in this walk of life is a problem that has consumed a forest full of research papers and focus group reports over the years, but to little effect. It isn't simply …

Why so much cynicism over "ultra-processed" foods (UPFs)? You report claims that the food industry's goal "is to maximise profits by cajoling consumers to abandon freshly prepared food". Why not say that the industry gives us the possibility of buying ready-to-eat food instead of having to do all the processing ourselves? And why say "they …

Perhaps there is no more ultra-processed food than lab-grown meat and plant-based alternatives.

S. W. Shaw calculates that around 9 million UK homes may have converted to using heat pumps in the next 15 years. However, millions of homes here are Victorian and broadly aren't suitable for heat pumps . Beyond those 9 million conversions, to really make progress towards net-zero housing, we may have to bulldoze all …

There have been welcome ideas from readers relating to carbon taxes, but an important added ingredient is needed to make them work, to prevent "carbon leakage" via the import of goods with high embedded carbon ( Letters, 21 October ). To that end, the European Union has created the Carbon Border Adjustment Mechanism (CBAM). It …

I am concerned about the impression that discarded toys generate more e-waste than vapes. While it is true that toys make up the majority of this in landfill, I suspect vapes make up the majority outside landfill and fly-tipping sites. Some ex-smokers discard them like cigarette butts ( 21 October, p 14 ).