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I read Graham Lawton's article on ageism with a degree of sadness ( 4 April, p 19 ). Yes, younger people will want to take over an older person's job because they want to get on in the world. That's human nature. But you still need a job, of course. I worked for many years …

I'm 75, yet I have never experienced the stigma Lawton talks about. That may mean I'm either oblivious to it or too self-centred to notice, but I don't think I am either of those. I interact with a lot of people younger than me by a generation or more, even though I wouldn't call myself …

As an aphantasic, I was fascinated by Shayla Love's article, "Think of an apple". One question that it didn't address is how people with aphantasia dream. My conscious mind's eye is completely blind – I cannot conjure up any images at all, but I am certain that I dream in pictures. One reason why is …

I found the article on mental imagery training very interesting. As described, I don't have very good mental imagery, but my spatial imagery is better than many people who do. I can also imagine myself moving my limbs and body, which may be related, but presumably also involves proprioception, and is extremely useful for learning …

There's nothing "radical" about the notion that "the cosmos is stitched together from interlocking perspectives" ( 21 March, p 28 ). Each of us views the world from a unique (relative) perspective, builds limited models of our environments and acts accordingly to sustain ourselves, shaping reality around us. When we think and work together, we …

Jo Marchant's article on QBism and enactivism suggests the state of the universe is refined through the process of observation or perception. A previous letter about building a simulation of the universe noted that if you were to do so and had limited resources, you would refine details of the model only as and when …

On the question of whether AI understands that nuclear war is to be avoided, I would say yes – depending on how it has been programmed ( 7 March, p 11 ). To explore the restrictions that large language models might have imposed on them, I asked ChatGPT a series of questions about the construction …

I appreciated Tom Gauld's proposed standard model of confectionery Easter egg structure. However, I fear it needs a rethink: I have an egg that, while possessing the chocolate shell exterior, fails to match any of the interiors mentioned by Gauld, as it contains a number of multicoloured sugar-coated chocolate sub-ovalic particles (Smarties) ( 11 April, …

The World's Largest Collection of the World's Smallest Versions of the World's Largest Things is located in Kansas (11 April, p 48).