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Graham Lawton describes rewilding as letting nature run things, so it can right the wrongs we have done Earth's wildlife ( 13 October, p 34 ). It is easy to make a case for this in an area of virgin forest cut down a decade ago to produce palm oil. But where humans have been …

I have serious concerns about how this will contribute to the debris environment Alice Gorman ( @drspacejunk ) is not thrilled at Elon Musk's plan to put 4425 satellites into orbit every 5 years ( 10 November, p 5 )

David Cole criticises Simon Oxenham for suggesting that a liberal outlook is the default in Western societies (Letters, 27 October ), and then says that the large parts of society that haven't thrived under neo-liberal economics and bewildering social change deserve respect. This risks confusion over the word "liberal". A liberal democracy is one in …

You reported on skin cells engineered to make an enzyme that destroys cocaine, which might be implanted to treat drug addiction ( 29 September, p 19 ). I wonder whether similar enzymes exist that destroy opioids and methamphetamine. Though on reflection, I wonder how useful this might actually be. Would cravings lead someone to take …

So cats are bad at catching adult rats ( 6 October, p 15 ). But cats do like catching and eating juvenile rats, which have a fighting weight a fraction of an adult's. I have seen the neighbour's cat trot by with a young rat in its mouth.

Tributes to Stephen Hawking rightly admire the mental resilience that enabled him to live a productive life with an overwhelming physical disability – including that by his daughter Lucy Hawking ( 20 October, p 42 ). None that I have come across mention the carers who enabled him to go on living. I have searched …

Alice Klein's comparison between hydrogen-powered and battery-powered vehicles was interesting ( 8 September, p 20 ). In a country like Australia the limited range of either type of vehicle outside of the major cities will be a problem for some time to come, for example because of a lack of fast charging points. But we …

"Great fleas have little fleas upon their backs to bite 'em, And little fleas have lesser fleas, and so ad infinitum ." Now we have moonmoons ( 20 October, p 10 ). May some have moons: so moonmoonmoons? We might need to abbreviate to m3moons, m4moons and so on.

You report a new chewing gum that "consists of a piezoelectric element and electrodes wrapped in a thin plastic film" ( 20 October, p 7 ). What are the environmental consequences of such a product? Our pavements are already heavily stained with discarded chewing gum. Will the new chewing gum also be discarded, adding to …

• Natalie Starkey is now a freelance writer and science communicator ( 3 November, p 38 ).