Letters archive

It is a mistake to pursue unproven high-tech solutions to storing carbon when we already have a proven technology that could be quickly and widely implemented: regenerative agriculture. This uses established techniques to create a living soil that can sequester a great deal of carbon per hectare. Conventionally farmed soil can be improved in three …

6 April, p 36 Kevin Healey, Sydney, Australia Eco-anxiety specialist Caroline Hickman suggests that "if we stopped oil extraction and shifted to renewables, eco-anxiety would almost disappear overnight". Even in the best-case scenario, the climate effects of these measures would take some time to be felt, and by then the focus will undoubtedly have shifted …

The J. Doyne Farmer interview on conceptualising the economy as a complex system with emergent behaviour was fascinating. As an ex-teacher, what I particularly enjoyed was the grass-zebra-lion analogy, comparing the interdependence of specialised entities in an ecosystem to those in the economy. Although an oversimplification, it was very easy to understand and was capable …

Dark matter remains quite an enigma. If it exists, we have to confront a situation where the big bang created two separate types of matter – the normal matter we see today or its precursor (making up around 20 per cent of the total) and dark matter (about 80 per cent). Alternatively, we may need …

When I taught undergraduates the scientific method, parsimony was a key element. I find this lacking in suggestions that we may live in a simulation. Two scenarios (among perhaps more): our lives are the result of material evolution that gives us the consciousness and intelligence to one day program such a simulation, or another species …

With all this talk of the quantum multiverse, many-worlds and now many-more-worlds, William of Ockham must be spinning in his grave. In multiple universes. 13 April, p 8

Thomas Metzinger's book, The Elephant and the Blind , has been made available as open access ( 27 April, p 28 ).

Chanda Prescod-Weinstein laments the shift to broad-spectrum white LEDs in towns and cities because of the impact on the night sky. However, go to any sizeable theatre today and you will see from the stage lights that LEDs can be any colour. It isn't obvious why most LED road lighting is white, and it isn't …

Prescod-Weinstein regrets that when street lighting was converted to LEDs there was no requirement that the white light be filtered to a single frequency, which would make it easier for astronomers to deal with. But that would defeat the purpose of converting to LEDs – their efficiency. Filtering out most of the frequencies would drastically …

In many countries, such as India, power generation is indeed moving noticeably away from fossil fuels, with significant reductions in carbon emissions for that sector. ( 4 May, p 8 ) However, the overall energy consumption and carbon emissions of many nations is changing far more slowly, if at all, due to continued reliance on …