Letters archive

Carl Zetie highlights the issue of those who say that a change of attitudes, not the use of weight-loss drugs, is the way to tackle obesity ( Letters, 6 July ). As has been pointed out many times, one reason why our ancestors avoided this problem was the struggle they had in accessing food. Hunting …

I don't think the universe is infinite, but instead is in the form of the "surface" of a four-dimensional Euclidean hypersphere, so is finite. Nor do I think our universe is the only one: there may be other "bubbles" like ours in the wider cosmos, of which our universe is only one part. To say …

Is the universe infinite? Space and time are assumed to have begun at the big bang. So, if our universe is expanding, it would need infinite time to become infinite in extent. Yet current theory maintains a beginning 13.8 billion years ago.

You ask: Is the universe conscious? The answer depends on what is meant by "conscious". If the definition is an operational one, the question can be settled by observation and experiment. If not, well, you can play more or less interesting semantic games ( 29 June, p 38 ). I think the nominal -ness suffix …

In your look at life in the universe, you say that almost all the stars that will ever exist have already been born, and they have been around long enough for life to arise on planets that orbit them. But we don't know that they have been around long enough for life to come about …

Chanda Prescod-Weinstein comments on the idea that the arrow of time is linked to increasing entropy. What this approach seems to miss is that, while in most systems entropy will almost always increase, there is a very small chance that a system will become more orderly, with lower entropy, just as a result of random …

In your story about getting UK climate goals on track, economist Michael Pollitt mentions the need to reduce the weight and size of vehicles. Why would anyone who wants to protect the environment design an EV that weighs more than 2 tonnes, leading to increased energy demand and road damage( 22 June, p 10 )? …

On exercises to stave off lower back pain, I discovered that regular hip waggling (twerking?) during tooth cleaning with my 2-minute cycle electric brush resulted in the pain completely disappearing. The only downside is that I have to make sure no one sees me – even at 90, I look incredibly sexy( 29 June, p …

Yes, carbon offsets for air travel don't work. I, for one, won't get on a plane until that changes. If we want to mitigate the worst effects of climate change, no one should be getting on aircraft. But people seem to feel entitled to fly to see threatened areas of the natural world for themselves …