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As medical microbiologists, we find the possibility of microbes on Venus tantalising ( 19 September, p 7 ). After all, our speciality could be on the verge of becoming an interplanetary discipline. Though the existence of Venusian microbes remains improbable, it is worth pausing to consider the risks inherent in the next step of this …

Your article on the global coronavirus toll as it neared 1 million deaths shed light on the chaos endured by human beings this year ( 19 September, p 10 ). But the information from the authorities has been conflicting, not least in the UK. The answer to your question "Can we trust the numbers?" seems …

The figure of 1 million global deaths needs to be put into context. It is about 0.015 per cent of the global population and is equivalent to those that malaria kills in 30 or so months – every 30 or so months.

There is an answer to Eddy Keming Chen's question, "how many grains of sand can you take away from the heap and still call it a heap?" ( 5 September, p 36 ) "Heap" has a three-dimensional vibe as a noun, and especially as a verb. Three or fewer grains can form a layer at …

I should like to add some nuance to Dan Falk's fascinating article on the possibility of advanced civilisations beyond Earth ( 3 October, p 36 ). The assumption behind the search for extraterrestrial intelligence is that such intellect is likely to be used to develop technology, but this isn't inevitable. The cultures of both classical …

Finding what is probably a sign of life in clouds on Venus ( 3 October, p 12 ) is eye-opening for anyone seeking extraterrestrials, a hint that we may be looking in the wrong places and that we shouldn't just be targeting planets in the so-called Goldilocks zone.

In your leader (3 October), you say that because there are so many planets, "even if the odds of life arising on a particular world are tiny, there is a good chance it has happened many times". Let's assume that there are 10 12 planets in our galaxy and 10 12 galaxies in the visible …

Annalee Newitz is right to conclude that "we are going to need better political systems" to deal with climate change, but I would go further (26 September, p 22). To deal with it, we will require unprecedented cooperation between people, industry and governments. The latter two groups will do nothing until they see which way …

I read your article on precision nutrition with great interest ( 12 September, p 34 ). It suggests that dietary response is, in part, associated with microbiome composition. Yet surely this is a catch-22, since microbiome composition is modified by dietary intake. It would seem that robust conclusions can only be drawn after long-term studies …

I have just watched your online event on Â鶹´«Ã½ 's coverage of the pandemic. What a pleasure to meet you all. More please. • The editor writes: For more virtual events, see newscientist.com/science-events