One of the more interesting concepts behind the interface was, everything was stored in one "circular" file, with marks for document beginnings and ends. By "circular" I mean that if you leapt forward from file to file, you'd eventually return to your starting point. The idea was, it's hard to remember the names of documents, let alone where in the filesystem you might have saved them. But you can usually remember something about the document -- some piece of text, etc. Using the leap keys you could quickly find the document you were looking for. Modern OSes allow for such searching, but at the time the idea of not worrying about file locations or names seemed very forward thinking.
Jef had research to show that "leaping" was superior (or at least, your productivity was faster) when comapred to other computer interfaces -- provided the user was used to using leap keys. Later I saw Andy Hertzfeld give a talk on Multifinder, and I thought the contrast between the two engineers was stark. The Canon Cat gave you one way to interface with the system (which was "the best way"), while Andy's interface gave you multiple ways to do the same task. Andy said something like "different people interact with the system differently" and he wanted to support all they ways they might want to do their work.
Right. Shields can protect against high velocity things, e.g. bullets or shrapnel. But not slow moving things, e.g. air and hands.
This contrivance means ancient weapons still have a purpose.
This effect is similar to non-Newtonian fluids. (In fact, there has been research into using non-Newtonian fluids for body armor [1].)
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> It would also seem that mankind lost the ancient secrets of body armour.
There are a few instances of armor in the movies (Harkonnens, Leo Atreides and Gurney Halleck, one of Paul Atreides' visions), but the books make virtually no mention of it.
The in-universe explanation is that the fighting style was much closer to ninjas than knights. Which means light-to-no armor was preferred.
[1] https://en.wikipedia.org/wiki/Liquid_armor
https://acoup.blog/2024/11/29/collections-the-problem-with-s...