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Sophie Attwood's observations made me nod in agreement. It is nonsensical to reject "artificial" foodstuffs while allowing synthetic materials to be pumped into our bodies for cosmetic ends and eating meat from animals stuffed with pharmaceuticals and industrially made cattle feed( 30 August, p 19 ). Touching on another of her insights, companies that now …

What a fascinating article about deciphering animal languages with AI. It is about time because, to date, a few dogs and chimpanzees seem to have learned far more of ours than we have of theirs( 30 August, p 36 ). I hope someone tries it with wild Brazilian macaws (which would be easy to set …

"All life that we know of needs liquid water." All life that we know of also exists on Earth. If we are searching for alien life, it is perhaps convenient to concentrate on water, but the possibility that life might exist without it shouldn't be overlooked. Life might also exist at sizes too small or …

A question about petrol lawnmowers ( Last Word, 23 August ) was posed by Hugh Meteyard.

I have just read your review of Clamor , a book about noise issues. It mentions the problem with medics not hearing the beeps from hospital machines after a while. I have a daughter with type 1 diabetes. She doesn't hear the beeping related to blood glucose sensors coming from her phone anymore. After spending …

I greatly appreciated your article on lesser-known food allergens. For some 70 years, I have experienced heart palpations and projectile vomiting when I eat cheese, but I don't have an adverse reaction to milk or yogurt. As cheese doesn't appear separately on the UK Food Standards Agency's list of allergens that must be highlighted on …

I understand Merten Reglitz's argument that internet access should become a human right. However, spending the best part of half a trillion dollars on this wouldn't automatically give people access to clean water, enough food, basic healthcare or the means to make a decent living to pay for these things, which they might consider a …

Your article on infinity deals with very large and very abstruse concepts of it. But what about smaller, everyday infinities? The number pi is something we use often enough, but it can only be expressed accurately with an infinite series of digits. This doesn't make it large – we all know that 4 is a …

Could it be that the number zero is another infinity? Does a perfect vacuum exist? Does absolute zero temperature really exist? It seems to me that both the physical and the mathematical worlds are bounded by at least two infinities.

Almost all of the problems with the mining of minerals vital to renewable technologies like electric cars can be solved by newer technologies: zero-rare-earth magnets, zero-rare-earth electric motors, zero-lithium supercapacitors( 23 August, p 36 ). The only remaining requirement will be copper. It is even possible that a form of carbon could replace copper in …