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I was both pleased and horrified by the article on Q-Day ( 25 April, p 10 ). Pleased, because the coverage and comparison with Y2K was accurate and measured, unlike some who declared it a hoax when, after the event, not that much went publicly wrong. I know it wasn't fake because, like many software …

I thoroughly enjoyed the excellent interview about dinosaurs and pterosaurs with Dave Hone, and it reminded me of my introduction to dinosaurs in the UK National History Museum when I was 10, some 70 years ago ( 2 May, p 40 ). My mother and aunt had taken my cousin and me on our first …

I found the article on the essence of reality very interesting. However, it isn't difficult to conceive of things being equally real whether we are considering our normal perceptions of the world ("red tomatoes") or more abstract concepts, such as quantum fields. We know that light consists of a continuous range of frequencies. However, our …

I can't pretend to explain how we experience time, but I'm sure it isn't what Tim Redman proposes. We don't observe something happening and say, "Oh, the entropy is increasing, so time must be flowing in a positive direction." True, the arrow of time can be related to a global increase in entropy, but we …

I have to agree with Tim Redman. Time is a human construct for measuring the "now" of successive events. Relativistic events appear so because the working parts of measuring instruments, namely clocks, are what are affected.

Regarding the article "Unlocking consciousness", it seems to me that the excellent and wonderful work of Nao Tsuchiya et al. is about perception, not consciousness. If we could map a cat's colour perception, I think we would find a similar web of contrasts and similarities. I think a cat is aware of colour, but I …

Andrew Dennant's description of being jolted awake by images while falling asleep, despite his aphantasia, mirrors my own experience. During the transition to sleep, I once "saw" an incredible, perfectly symmetrical gem with fantastic colours. Even in that hypnagogic state, it felt genuinely present ( Letters, 25 April ). Upon fully waking, I knew that …

I had to laugh at John Jared's thoughts on the potential difficulties of enforcing a social media ban, given the ingenuity of school-aged children. Many years ago, in an effort to stop my kids from watching TV as soon as they came home from school, I put a PIN on the TV ( Letters, 2 …