51¶¯Âþ

Reading about the use of abstract geometry in the search for a theory of everything, I was intrigued by Renate Loll's take: causal dynamical triangulation, rooted in the simple geometry of triangles and tetrahedrons ( 10 February, p 32 ). This reminds me of one of geometry's great treasures, as Johannes Kepler put it: the …

Given that the asteroid Bennu is in roughly the same orbit as we are, is it possible that the "small, ocean-covered world with conditions favourable for life to emerge" that the rock came from is Earth? Maybe created in the same impact that tore the moon from our planet( 10 February, p 8 )?

I liked David Robson's piece on subverting memories of a work session by ending with a fun task. But the assumption in a study he cites that the supposedly onerous tasks of isometric exercise, book sorting and dealing with customer complaints are "tedious" is very subjective. I get great satisfaction from sorting books and indeed …

While I worry about excessive car use, let's not forget that only in cities or large towns would you have a choice of alternative methods of transport if car use were to be made more costly. In rural areas, an affordable car is vital, as public transport is limited or non-existent. You could have food …

In making the case for more time working face-to-face rather than from home, Robin Dunbar highlights friendship benefits of the former, adding that the ideal number of close friends for good health is five, including close family. This means most people have enough such friends without needing any at work ( 10 February, p 21 …

Dunbar suggests other people's experiences of working from home were very different from my own. Lockdowns meant no long commute each day and very few interruptions, allowing me to get more done. It is nice to work with friends, but I have friends who will remain with me beyond this job.

Peter Leach quite rightly derides NASA working on commercial supersonic flight. However, there is one potential important customer: the US military, which probably lacks the expertise to develop large supersonic aircraft ( Letters, 10 February ). I can imagine it needing these to move specialist personnel and mission-specific equipment from a central base in the …

Physicists may have stalled in their search for the theory of everything because of the presumption that the universe is limited to three spatial dimensions. If they are now going to use geometry in their hunt for a final theory, they may be able to get somewhere by investigating the use of tesseracts or other …

The search for a neatly packaged theory of everything is fun and fascinating. It is often difficult for the average science buff to follow the brilliant work of geniuses. However, I believe that we wrongly expect there to be a lower "size" limit to our universe, which suggests a boundary – albeit usefully – in …

Many previous studies have found that taking notes with pencil and paper in class or when revising is more effective than doing so with a keyboard, but it was interesting to read your report on the possible neurological explanation for this effect. In light of the evidence, it would seem wrong to pursue the idea …