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Some years ago while diving around the island where I live I've noticed that this coral always makes a right-handed helix. I wonder if it might be an adaptive feature or, more generally, what could cause it. I mean, I saw dozens of them and never one turning left...

Look up the words "chirality in Nature" and you'll find more wonderful examples of this. Chirality is the property of being distinguishable from your mirror image. https://en.wikipedia.org/wiki/Chirality I don't know whether it's related, but for most proteins, only one chiral version is present in Nature, at least in this part of the galaxy. The left-handed version is here, but the right-handed version is not, or is biologically irrelevant.

You’re mis-applying the principle here. The shell theorem applies to spherical symmetry, but you don’t have a finite sphere in this case. You have to have all the mass enclosed within R to apply it. You can look at translational symmetry, too. If you have a uniform distribution of mass, you can choose any origin you want and get the same answer, so there can’t be an acceleration toward any point.

Could you ? Calculus was mentioned late in this thread. Consider Hobson's calculus (Theory of functions of a real variable) Volume 1 (originallly1907) My third edition 1927 736 pages 190 x 260 x 40 mm 1496 kg. Volume 2 My second ed 1926 780 pages 190 x260 x45 mm 1547 kg Both bigger than either my modern Setwart or my Finney. How about Wells - Structural Inorganic Chemistry My 1962 3rd edition weighs in at 2150 kg 1055 pages at 170 x240 x 80 mm.

Not directed at the Taiwan situation, but Trudeau weighs in on some of China's economic tactics. Though not directed at military concerns, I think it is relevant given the importance of politico-economic pressures, or the potential threat of them. https://globalnews.ca/news/8466217/trudeau-china-countries-need-united-front/ "Xi Jinping’s China today is “no longer the China that we thought about 10 years ago or even five years ago in some ways,” Trudeau said."

! Moderator Note Threads merged. One per topic, please.

I see nothing unethical about it. I also don't see any limits on the uses of any idea in the public domain. GODS know, the concept of deity, sanctity and the individual identities of each specific deity have been put in the service of less savoury projects!

I didn't realize that. I thought the size, weight, richness, etc. of the textbooks was part of an educational experience. I didn't mention instruction external to the textbook until after you suggested that the comprehensive content of these new, giant textbooks renders live instruction superfluous. Only in that context would the cost ratio of book to instruction be relevant: i.e. If this is indeed the case, it justifies the large format, thick, lavishly illustrated, entertaining and very attractive textbooks. Otherwise, their extravagant production values seem to me quite wasteful. Business college was just one example: it's the same in humanities and science courses. If I recall correctly, the most expensive of all were Physics books. The major difference, tmm, is that the science ones contain more factual, usable information. None of my comments were intended as more than personal observations and opinion.