Tuesday, June 19, 2007

Settling the Universe Without Magic Wands

Charlie Stross takes a hard look at the realism of space colonization, absent multiple technological magic wands. Without them, a lot of the traditional models to justify space colonization don’t make sense. Lunar wheat farming for export? Get real. L5 cities building solar powersats? Probably vastly cheaper to put up some cramped construction shacks and pay the workers enough to put up with conditions no more comfortable than a North Sea oil rig. Mars as a new Oklahoma? How do you close the business case? If you just want living room it’s a lot easier to garden the Gobi Desert.

Here’s one that might work: mining helium 3 from Jupiter or Saturn’s atmosphere. The potential economic value of the product is immense, it’s too far for teleoperated robots, and too tricky for autonomous robots. It’s also too far to easily send the workers back to Earth for R&R.

Interstellar colonization is a lot tougher. It looks like even with a perfectly efficient drive requiring no reaction mass, sending a 2,000 kg capsule to a distant star at .1 c will take energy equivalent to about 400 megatons of thermonuclear devices. Doing the job with, say, less than perfectly efficient lasers and lightsails will cost a lot more, even if you assume a lightweight unmanned precursor mission of self replicating hardware that lands on a moon on the target system and eventually covers the extrasolar lunar surface with a laser array to stop the heavier capsule.

At that rate, the usual historic economic models for colonization don’t work. The potential payoff is so far in the future that no rational investor would fund the project.

That doesn’t mean that interstellar colonization is impossible, but it does mean that constructing a plausible scenario without magic wands is a lot harder, just as writing a sonnet is harder than writing prose.

Option 1. Funding an extrasolar colony is a luxury good for very, very rich societies. If the society is rich enough, it can fund it out of the very small slice of economic activity allocated to pride, prestige and warm fuzzy feelings, like the .2% of GNP that the US spends on NASA. Continue plausible compound growth as needed. A very rich society might found a half dozen extrasolar colonies over the course of a millennium. Once founded, the only economic exchange between systems is the barter exchange of intellectual property by laser or the like. If this seems like a cramped and limiting future to write about, remember that most authors manage to find plenty of story ideas set on a single solitary planet.

Option 2. Assume the same rich society in the Solar System. A large share of the economic activity is intellectual property. Perhaps 10%, perhaps more. An alien civilization 30 light years away makes contact, or vice versa, and begins trading intellectual property, which eventually equals 5% of the Solar economy. How much is it worth the Solar System to have at least one human in the distant system to make trades without a sixty year time lag between exchanges? A lot.

Finally, here’s one answer to the singularity problem. Once you get artificial intelligences of roughly human capability, what stops them from rapidly upgrading themselves to superhuman intelligence, weakly godlike powers, strongly godlike powers, etc?

Possible solution: Ethical A.I. Once the program can pass a Turing test, both humans and A.I.s consider deleting or mothballing the program the moral equivalent of murder; which it would be. Every single new iteration of A.I. that can pass a Turing test needs to be given a fair start in life as a free business machine. A.I. progress slows to a crawl, and the singularity is postponed for millennia.

Monday, June 18, 2007

How to Hold a Lance in Combat on Foot

What’s the best way to hold a lance or spear when fighting on foot? A variety of fighting manuals illustrate its use in single combat. Typically, the hands are an arms length apart, so the point halfway between the hands is a useful point of comparison. Fiore dei Liberi, writing ca. 1409, shows a halfway point that varies from the middle of the spear to two thirds of the way back from the point. Filippo Vadi, who owes much to Fiore, shows a similar preference in his manuscript dated 1482-1487.

The earlier portion of the Codex Wallerstein, probably from the first third of the 15th c., shows a halfway point about two thirds of the length of the shaft back from the tip. Talhoffer’s 1459 manuscript, now in Copenhagen, shows spears held either near the middle of the shaft or about two thirds of the way back. Paulus Kal’s fechtbuch from the third quarter of the 15th c. shows spears held near the middle of the shaft, also with the hands about an arms length apart.

Olivier de la Marche gives an interesting description of a combat with lance on foot between Galiot de Baltasin and Philippe de Ternant. De Ternant took his lance with “the butt in his right palm, and the held the lance at the balance point with his left, and carried it more upright (droicte) than couched.” In contrast, his opponent held his “in the ordinary way one holds a lance for pushing” De Ternant’s stance is evidently seen as somewhat unusual, and different from the default position, which was so common that it did not need description.

Holding a lance with one hand at the butt gives maximum reach. Why was the position disfavored? Di Grassi, writing in the 16th c., describes the arguments for different hand positions on a pike. Although the pike is a longer weapon, the same tradeoffs apply, if to a lesser degree, with a shorter lance or spear:

This renowned weapon hath beene of divers diversly handled, in single combat: (for the manner of using it in the warres, maketh not at this present for my purpose.) Therefore it shall not be amisse, if (speaking of the manner of his use in these are daies) I declare also mine opinion concerning the same. There have beene some (who greatly regarding ease & little paine) would have the Pike to be borne in the middle. Other some, more strong of arme, but weaker of hart, (to the end they might be the farther off, from hurte) accustomed to beare it at the beginning neere the heele or blunt end thereof: which two waies in my judgement are to be refused, the one being too daungerous (I meane the bearing of it in the middle) the other too difficult (I mean, the bearing it at the blunt end,) because a man is not able to stande long at his ward, neither to defend himselfe strongly, nor offend safely, considering, much of his force is taken away, by susteining and bearing it at the said end. So that, when a forcible blow commeth he hath not sufficient power to beat it off. And forasmuch as the Pike is a long straight lyne, which hath his motion in the head or beginning thereof, which motion be it never so finall, neere the hand, is yet verie great at the point, it is requisite, if he would strike just and straight, (when he so holdeth it at the end) that he be greatly practised, and have great strength whereby he may be both skilfull & able to beare it so just & even, that the point thereof strike or hit there where the hand & eie would have it. This is verie hardly accomplished, aswel beecause it is a thing impossible to strike by the straight lyne, as also for that the armes being weakened with the paize of the Pike, do shake and deliver unstedfastly. Therefore, for the avoyding of these two inconveniences, the Pike must be born within an armes length of the said heele or blunt end, in which place, it is sufficiently distant from hurt, & it is not borne with much difficultie if the hands be placed an armes length one from another of the which the hinder hand must be stedfast, I meane, holde the Pike harde, and the forehand somewhat loose: So that the Pike may shift through it to and fro.

Presumably similar logic was thought to apply with the shorter spear or lance: grips at or closer to the center of the shaft were less tiring, and allowed swifter parries and better point contol.

Talhoffer 1459

Talhoffer's Alte Armatur und Ringkunst of 1459 is now webbed here, with a transcription, translation and commentary.