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James Wong was spot on regarding the poor economics of growing your own produce. But it is important to also consider other, non-economic, factors. These include convenience and flavour – closely linked to freshness. But perhaps most important is the availability of what you want ( 21 September, p 44 ).

There are further factors that could affect city atmospheres and feasibly increase rainfall in urban areas: water vapour released by burning fossil fuels and the use of evaporative cooling ( 21 September, p 15 ). Multi-megawatt quantities of heat and plumes of saturated air are probably being emitted into ambient air around the clock via …

Matt Strassler is right regarding words used in physics that can mislead. Changing them might go a long way to clarifying things ( 21 September, p 32 ). For example, instead of using a word like "particle", give it a new name – "omet" – and then list the characteristics of omets. They are atomic …

5 October, p 40 In the interview with Sophie Koudmani, we read yet again of misgivings about the size of monstrous black holes in our early universe, and concern at the lack of time to reach such proportions. Would it be a silly or outrageous idea that such black holes may have existed before the …

Rowan Hooper's column about a future food revolution paints a seriously worrying dystopian picture. This vision would leave food production in the hands of corporations and subject to the vicissitudes of supply chains, political disruption and so on ( 14 September, p 24 ). The creation of megafarms already means farming is starting to come …

The man pictured near the Soyuz MS spacecraft is ground crew (5 October, p 26). US astronauts Peggy Whitson and Jack Fischer and Russian cosmonaut Fyodor Yurchikhin are inside the vehicle.

"We are on the brink of an irreversible climate disaster," write William Ripple and colleagues at Oregon State University in their report on the state of the planet. As there are no indications of effective global cooperation, or political leadership, to tackle this emergency, we need parallel arrangements. I mean education and training to prepare …

I enjoyed Chanda Prescod-Weinstein's look at stepping outside her scientific comfort zone. It reminded me of a line in Kurt Vonnegut's novel Player Piano: "Show me a specialist, and I'll show you a man who's so scared he's dug a hole for himself to hide in." As a physicist who has spent my working life …

"Reimagining democracy" starts by noting that current "democracies" favour the rich. It ends by reporting that an attempt to roll out a more truly democratic model across the UK has been vetoed by government because "there is no money". Turkeys, of course, don't vote for Christmas ( 5 October, p 32 ).

In her article on why we avoid effort, Amanda Ruggeri mentions the so-called IKEA effect: that we prefer a less well-made bookshelf that we have assembled ourselves over something ready-made and perfect. "Our effort," she says, "adds value." ( 5 October, p 36 ) I would say we underestimate the importance of our ability to …