Letters archive

You report that spraying salt water into the atmosphere over the Pacific to brighten clouds for nine months a year for 30 years to save California from extreme heat could eventually cause dire temperature increases in Europe as a side effect ( 29 June, p 11 ). However, other studies are more hopeful about such …

The idea of our cosmic insignificance is a matter of emotion rather than reason. We all feel it, but it does, after all, involve equating physical size with significance. This is absurd, as we don't say an elephant is more significant than a human, or a mountain than an elephant. What happens is that, when …

What a magnificent photograph of the Milky Way seemingly emerging from the summit of Aoraki/Mount Cook in Aotearoa/New Zealand. In it, our galaxy also seems to be looking down on the rapidly retreating terminus of the Hooker glacier and the equally rapidly expanding Hooker Lake. By 2016, this lake had lengthened from nothing to 2.5 …

There is one vagus nerve on each side of the human neck ( 29 June, p 19 ).

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.

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 …

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 …