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Thursday, 27 January 2011
At a party in Washington in November 1954 a general confided in Richard Feynman that what the army needed was a tank that ran on sand...
The entire global capacity to generate electricity is about 5 TW.
To give you some idea of how big that is, if you were to weigh all the electricity humans generate in a year (we're talking E = mc2 here) it would come in at about two tonnes. A year of the world's electricity weighs about as much as a small truck.
To give you some idea of how small that is, if you were to cover a 200 kilometre square of one of the world's deserts near the equator with solar photovoltaic cells, they would comfortably generate more than 5 TW, at least in the daytime. That's an area slightly bigger than Devon and Cornwall, or Greater Los Angeles. A square metre of PV cells costs less than a square metre of Los Angeles.
But we don't want to plod about in deserts laying down PV cells that we've made in factories on a different continent. It's expensive and, worse, it's hard sweaty work.
PV cells are made of silicon. A desert (to a first approximation) is also made of silicon. Getting that silicon out and turning it into PV cells needs energy, of course. But if you have some PV cells to start you off, you have some energy.
So. Let's build an autonomous robot that crawls slowly over a desert shovelling up the ground and refining it into solar cells. These it connects up and lays down behind it as it goes, keeping its own connection to them to power the refining process.
After many years the PV cells will lose efficiency as they get scratched by sandstorms and the like. The robot could work in a continuous cycle, like painting the Forth Bridge, going back to its start point then grinding up the worn old cells and re-refining them back to brand new ones in its wake.
Free green electricity for everyone for ever...
Wednesday, 19 January 2011
All technologies that we create, create problems - just think of the motor car. But on balance every single technology that we have created has given us more than it has taken away.
Every single technology except one: explosives. Explosives do have limited beneficial uses: mining, quarrying and demolition come to mind. However, the principal use of explosives is the opposite of beneficial - it is killing. What's more, virtually every machine that we make for killing relies on explosives. These machines range from those such as the suicide vest or the nuclear bomb that have killed comparatively few people, to viscously lethal weapons of mass destruction such as the assault rifle.
And the beneficial uses of explosives all have alternatives. Mining, quarrying and demolition can be done with expanding collets driven by very high-pressure hydraulic oil. Explosives are a little cheaper for the job, that is all.
At least since the invention of agriculture in Mesopotamia 12,000 years ago, humanity has been doing genetic engineering. These days this is achieved by the direct editing of DNA, but the old way - selective breeding - still works well, and it can be done by anyone. It is particularly easy to breed microbes selectively. Suppose you want a yeast that will produce (and tolerate) higher concentrations of alcohol. You just set up a few dozen small fermentation vessels, add yeast to each, and drop in a little extra alcohol. Those yeasts that survive you breed from; the rest you discard. Repeating this process over a few weeks (upping the alcohol each time) will give you a surviving yeast with much higher alcohol tolerance than its wild forbears.
What has the selective breeding of microbes to do with alleviating the misery caused by explosives? Well - explosives are organic molecules with a lot of energy locked up in their chemical bonds. In other words they are an ideal potential food source for yeasts, bacteria and archaea. But explosives haven't been around for long enough for such explosive-eating microbes to evolve by natural selection.
So why not apply artificial selection to the problem? Dope the nutrient medium in a collection of petri dishes with small quantities of many explosives, add a large number of different microbes (sewage would probably be a good source) and pick out those microbes that do well. Gradually reducing the conventional nutrient and upping the explosive content over the generations should select for those organisms that can digest the explosives best. And, as the microbes multiplied through the explosives, they would neutralise them by using up chemical energy. The energy would still be released - ultimately as heat - but harmlessly over weeks rather than lethally over a microsecond.
It might be an idea to add a little brass and steel to the breeding mix, so that the bugs could also work up the ability to etch through shell casings to get at their lunch.
The result would be that ammunition would turn to harmless goo in its magazines and that bombs would rot in their silos.
A world elevated to using bows and arrows again would not be completely peaceful. But it would be a lot more peaceful than the world that explosives has created.
Thursday, 13 January 2011
Bitter is the taste of poison. Almost all toxic substances taste bitter to some extent. And some things - particularly some harmless plants - taste bitter even though they are not poisonous. This is for the same reason that a harmless hover fly looks like a wasp. The plant has evolved a bitter taste after animals that might eat it evolved to flag up poisons using their sense of bitterness. Think cabbage; think coffee.
Children don't eat their greens because they are very sensibly resisting their mad parents' attempts to poison them. Parents do eat their greens because they have learned that they get sustenance (or - more immediately - a caffeine hit) by overcoming their initial revulsion. Indeed, most adults have conditioned themselves actively to like bitter - coffee and pink gin are treats.
But if such a diverse range of chemicals all give rise to the same taste, that must surely mean that there are receptors on our tongues for all those many different molecules? Most poisons work by binding to some specific vital body protein and so stopping it from doing its job. Maybe the way that evolution has designed the bitter area of our tongues is simply to take all (or a lot of) the proteins that - if blocked - would stop us from working, and to wire a small sample of each one in our taste buds into the one bitter signal to our brains.
Now most drugs work in the same way as most poisons - they bind to specific proteins to slow or to stop their function. Indeed, many drugs are poisons if taken in super-medicinal doses. And most drugs taste bitter.
Perhaps an easy way to find lots of useful new drugs would be to find just those proteins wired into our bitter taste buds, and then look specifically for substances that bind to them.
Thursday, 6 January 2011
Ever since it was devised, people have sought to improve on the QWERTY keyboard - the Dvorak keyboard above is a famous example. Of course, there is a sense in which an established order is best simply because it is established. For example, try to think of an improvement on this arbitrary sequence: ABCDEFGHIJKLMNOPQRSTUVWXYZ.
But clearly there is an ergonomic aspect to a keyboard that ought to admit of some sort of optimisation. So why not make keyboards so that you can unplug and swap the keys? Then people could experiment to find the pattern that worked best for them. Optionally, a mouse click could upload that pattern to a central website, where statistics on popular (and unpopular) patterns could be gathered.
Then we could just let the best patterns evolve...