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I don't buy the idea that "we make reality". I believe subatomic entities exist independently of us and that these entities oscillate and interact with wave-like properties. However, the equations we use to describe these interactions are human-made, so it is at this point that we create our own reality. ( 12 October, p 40 …

The idea that there is no objective reality puts the "observer" centre stage. But what constitutes an observer? Much of quantum physics avoids this issue, implying that only humans qualify. Surely it is arrogant to think that only we can be observers? If the history of science teaches us anything, it is that making humanity …

Oriti, a theoretical physicist, says that "we have to embrace the fact that we make reality". That might come as a shock to scientists, but not to poets and novelists: they have always thought it obvious that reality inheres not in the common phenomenal world, but in the perceptions of that world in individual minds.

If we make reality, are we part of reality or not? If we are, do we make ourselves – and all our thoughts, theories and so on? And if not, why not?

Leah Crane's article about seeing Saturn through a telescope as a child and being inspired to love space was fascinating. It called to mind philosopher Bertrand Russell, who, although an atheist, freely admitted to the immense mystery of the cosmos: "We know very little, and yet it is astonishing that we know so much, and …

You suggest that geoengineering is now essential to save the Arctic's ice based on the results of a recent sea ice restoration trial, arguing that "to buy us time and to buttress this delicate habitat from a warming world, geoengineering is probably our only hope" ( Leader, 28 September ). If this were an early-stage …

It seems to me that the free-energy principle (FEP) is little more than a restatement of the principle put forth by chemist Henry Louis Le Chatelier: "If a system is subjected to stress, the system will respond in a manner that tends to mitigate the effect of the stress." I can't see that the fuzzy …

Rowan Hooper's musings on future robot pets brought to mind two things. The first was the Furby, an electronic "pet" developed in the late 90s. It could respond to a variety of inputs with changes to its facial expression and speech. All its abilities were programmed into it and the Furby wasn't connected to outside …

I applaud Eric Kvaalen's idea of using solar arrays on the International Space Station as solar sails that might keep it in orbit. Few places would be better suited to testing designs for solar sails. As for the favoured plan to bring down the ISS, I deplore the mindset of those who would scrap a …

The richest 1 per cent of the US population is responsible for more carbon emissions than the entire lowest-income 50 per cent. Your article on this advises more climate policies targeting those responsible for the largest emissions, with inheritance and wealth taxes. But there could be a fairer, clearer way to hit them straight in …