Terry Pratchett - The Science of Discworld III - Darwin's Watch

Literally, 'jointed acorn'

Yes, we know it sounds unlikely, but apparently there are such things.

It was a good job that God had such a fondness for beetles.

Its potential for Librarianship was not widely recognised at that time.

No, not long-haired South American beasts of burden, but Latin for `gaps'.

The term was around in Victorian times, as a phenomenon but not a specific mechanism. Darwin didn't use it in Origin, nor in the later The Descent of Man. However, the final word in Origin is 'evolved'.

To see why, double it: the result now is 2 + 1 + V2 + '/ + y8 + 'A+ ... , which is 2 more than the original sum. What number increases by 2 when you double it? There's only one such number, and it's 2.

If you've never encountered the mathematical joke, here it is. Problem 1: a kettle is hanging on a peg. Describe the sequence of events needed to make a pot of tea. Answer: take the kettle off the peg, put it in the sink, turn on the tap, wait till the kettle fills with water, turn the tap off ... and so on. Problem 2: a kettle is sitting in the sink. Describe the sequence of events needed to make a pot of tea. Answer: not `turn on the tap, wait till the kettle fills with water, turn the tap off ... and so on'. Instead: take the kettle out of the sink and hang it on the peg, then proceed as before. This reduces the problem to one that has already been solved. (Of course the first step puts it back in the sink - that's why it's a joke.)

Yes, traditionally `Indigo' goes here, but that's silly - Indigo is just another shade of blue. You could equally well insert `Turquoise' between Green and Blue. Indigo was just included because seven is more mystical than six. Rewriting history, we find that we have left a place for Octarine, the Discworld's eighth colour. Well, seventh, actually. Septarine, anyone?

This is why, even today when the lustre of `the new mathematics' has all but worn to dust, small children in mathematics classes spend hours drawing squiggly lines between circles containing pictures of cats to circles containing pictures of flowers, busily `matching' the two sets. Neither the children nor their teachers have the foggiest idea why they are doing this. In fact they re doing it because, decades ago, a bunch of demented educators couldn't understand that just because something is logically prior to another, it may not be sensible to teach them in that order. Real mathematicians, who knew that you always put the roof on the house before you dug the foundation trench, looked on in bemused horror.

Briefly: since the bit before the decimal point is a whole number, taking that into account multiplies the answer by aleph-zero. Now aleph-zero x aleph-zeroplex is less than or equal to aleph-zeroplex x aleph-zeroplex, which is (2 x aleph-zeroplex, which is aleph-zeroplex. OK?

The proof isn't hard, but it's sophisticated. If you want to see it, consult a textbook on the foundations of mathematics.

Curiously, it could expand to infinity in a finite time if it accelerated sufficiently rapidly. Expand by one light-year after one minute, by another light-year after half a minute, by another after a quarter of a minute ... do a Zeno, and after two minutes, you have an infinite universe. But it's not expanding that fast, and no one thinks it did so in the past, either.

Actually a more sophisticated gadget called the Poincare dodecahedral space, a slightly weird shape invented more than a century ago to show that topology is not as simple as we'd like it to be. But people understand 'football'.

Derived from a pun: m-bran for `membrane'. Opening up jokes about no-branes and p-branes. Oh well.

Counterfactual: a more acceptable word for what has for a long time been a very common feature of science fiction, the 'alternate world' or 'worlds of if story (there was a pulp SF magazine in the 1950s called Worlds of If, in fact). 'Counterfactual' is now used when said stories are written by real writers and historians, to save them the indignity of sharing a genre with all those strange sci-fi people.

Well, there might be ...

See The Science of Discworld.

What would have happened - if Darwin had gone back in time and killed his own grandfather?

They made exceptions for manifestly `unimportant' but very diverse sets of alleles like blood groups, but in those cases it didn't seem to matter much which kind you had.

That's very important for a few species. Zebra-fish eggs in the wild must hatch in just under 72 hours, because they're laid just before dawn and must hide before the third dawn when predators could see them.

Sorry about the proliferation of barnyard metaphors.

The University's proctors were known as lobsters because they went very red when hot and had a grip that was extremely hard to shake off. They were generally ex-army sergeants, had depths of cynicism unplumbable by any line, and were fuelled by beer.

Pronounced `crazy'.

This is a special usage devised by the anthropologist Lloyd Morgan in the 1880s, picked up by John Campbell Jr in an Analog editorial in the 1960s, then by Jack in The Privileged Ape: for tribal humans, everything is traditional, mandatory or forbidden; for barbarians, action is driven by honour, bravery, modesty, defiance of precedent; for citizens, some roles are tribal, some barbarian, we choose.

Not quite including the confectionery, which was the surname of the originator; he came to England from the USA, and invented M&Ms too. That stands for 'Mars and Mars'.

Also egg-laying. Jack, reading Burroughs when young, was disturbed by the idea of their marriage bed ...

Rajith Dissanayake, 'What did the Dodo look like?' Biologist 51 (2004), 165-8.

Although it does seem a little strange that Palestinian terrorists protect their genitals, for use in Paradise, when setting themselves up as suicide bombers.

See Jack Cohen and Ian Stewart, The Collapse of Chaos (Viking, 1994).

In their 1980 book Autopoiesis and Cognition, Humberto Maturana and Francisco Varela confused this kind of recursion with a life force, and called it 'autopoiesis'. Many selfconsciously modem management experts cite this concept, without having the foggiest idea what it is.

When Jack started at Birmingham University in the 1950s, the factory behind the university made cooking pots for missionaries, just like the ones that were popular in the cartoons in Punch - with the missionaries as ingredients, not cooks, you appreciate. No doubt the same factory had once made the original sauce vats used in Madagascar and Goa.

Details can be found in many personal diaries, such as those kept by the foremen of the spinning and weaving mills in Lancashire as exercises in writing for their evening classes. We learn that sexual engagement with women employees was sometimes necessary for these men, in order to retain the respect of their colleagues, to maintain obedience by the workforce, even when they found it horrible themselves. In the armed forces, of course, and in prisons, the social 'rules', the peer pressure to sin grossly, were too powerful to resist, too awful for us to contemplate now.