Posted: Mar 27, 2022 7:47 am
1. Professor Unrat, Heinrich Mann
2. God is not Great, Christopher Hitchens
3. The Ill-Made Knight, T.H. White
4. Northern Lights, Philip Pullman
5. The Subtle Knife, Philip Pullman
6. The Amber Spyglass, Philip Pullman

7. The Character of Physical Law, Richard Feynmann

This is not one of the books that I had on the go the last time I posted in this thread: I took myself by surprise by picking it up and reading it - or re-reading it (though I'm not sure that I had ever read the whole thing from cover to cover before).

Why? It started with my daughter, who is, very pleasingly for her mother, developing an interest in physics. She's doing well in physics at school, but it's still very elementary: they've been doing basic concepts like momentum, and looking at simple electrical circuits; all sound stuff, but I suspect she's gathered from me that physics becomes so super amazingly cool once you get into much deeper ideas.

Recently she had a question about the second law of thermodynamics, which I had evidently talked to her about before, and we went through it, how it works, and why it's so fundamental to the way the whole universe works, at all scales. We went through the classic example of two different coloured gases in a box, separated by a partition, and what happens when you slide out the partition, and why. She got that, and then asked, well, what if one of the gases is heavier than the other: they'll still be ordered, won't they, even after time. And that's quite true, but I pointed out that it's not a closed system if gravity is allowed to have an effect, and the second law only applies to a closed system.

And the next thing she said merits its own paragraph, because it was so good: What if gravity is inside the system? So we're looking at a whole planet, and in fact this is the whole universe, no stars or anything around to muddy up the picture with their own gravitational fields, and we then do the experiment with the gases in a box? Or just with some gases around the place, never mind the box. Everything will collapse to the centre, won't it? (my daughter has known for years that this is how stars form), and if that isn't order, what is?

Such a good point. So I was able to explain (after a slightly stunned interim period while I remembered that the universe consists of energy as well as mass) that the second law is obeyed once you consider the increase in entropy in the heat, and in explaining entropy, including the alternative definition as energy that is unavailable for useful work, I resorted to the wet towel comparison in the classic Feynmann lecture. I've never forgotten that, and I enjoy re-reading that passage now and again ("...pretty soon you discover a horrible thing...").

And that's what inspired me to re-read the whole set of lectures: partly because I thought they might help me formulate some more physics in laygirl's terms, when my daughter has her next questions, but also because they're simply fun to read.

I've also finished in the meantime two other books:

8. Dirk Gently's Holistic Detective Agency, Douglas Adams
always a pleasure to re-read this one
and 9. Knight Crusader, Ronald Welch.
Why on earth did I read this children's book? Well, because of when Kaleid mentioned Henry Treece, and I thought, my goodness, I haven't heard that name since I was at school, and that got me thinking, and remembering, and I remembered this cycle of novels all covering the adventures of various members of the same family over centuries of English history, which I must have read from the school library when I was about 12. So I looked it up, re-discovered what it and its author are called, and downloaded the first one on Kindle.
What a boys' book this is. And how politically scandalous (the Crusaders had absolutely no business occupying that land in Palestine). And above all: how did I not notice those two things, especially the first one, when I read these books the first time?