Tuesday, May 10, 2005

Maxwell's Demon vs. The Sun

One of my projects right now is building an electric bicycle that will let me commute 8 miles each way to work every day. I'm shooting for something that will cruise at 30-35 mph, though that is well above the 20mph maximum the state of Georgia will allow for such a contraption. More on these bikes later...

In my research, I found people who had success with folding solar panels for recharging the bicycle. (The bike will go 30 mi. a charge.) Along the way, I ran across some very interesting solar applications. There is the solar oven that is being used by campers everywhere and has become a viable response to third world wood-fuel use and its environmental devastation. A more sophisticated oven uses a reflective parabolic dish the size of a DirecTV antenna. With these, they have generated hotspots 900-1500 degrees F. I think I might collect a few of these, coat them with Mylar and see if I can't build myself a solar grill. Beyond dishes, people have been experimenting with large, flat fresnel lenses for focusing sunlight. Big ones (40") are for sale for about $60, and they get hot enough to blow a hole in a concrete sidewalk.


*Scientists cooking with sunlight

Many people assume that solar power is limited to photo-voltaic cells, which have a very low efficiency - something on the order of 7%. More efficient technologies for solar-to-electric conversion are the mirror fields of Arizona that focus sunlight on a tower and store heat in molten salts.

Another perhaps more promising mode is the use of the Stirling Engine for solar-thermal generation, which turns out to be the most efficient generation system yet. The Stirling concept has been around since the late 19th C., but has only recently been put to real use. Most of them can be found in novelty sciences stores. A small sterling engine can be powered with the heat from one's hand OR an ice cube. The idea is that the engine only needs a differential of heat to go - i.e. one cylinder hot and the other cold. Thus it can be powered with a coffee cup and cool air.

In the case of sunlight, the Stirling engine works best when the air is cool and the sun is bright. Warmer air narrows the differential. But let's say that the sun heats the air consistently. In that case, the degree to which you could concentrate the sunlight would provide the differential needed to drive the Stirling engine. All you have to do is carve the right grooves in the piece of glass that you place between the sun and the engine. That is, the glass would need to be inscribed with the right information.

The whole thing reminds me of Thomas Pynchon's The Crying of Lot 49, a novel essentially about information systems. On the hunt for a secret, underground mail system that had been around since Elizabethan times, the main character is led to a rather wizardly man's house. The man brings out a two-cylinder engine and sets it on the table. This engine, in my read, is the metaphor for the entire novel. The engine runs on the principle of Maxwell's Demon, an idea advanced by the nineteenth-century mathematician, James Clerk Maxwell. Here's the idea. Imagine a box filled with air and bifurcated with a partition. Molecules are bouncing off the walls, some slow, and others fast. If there was, say, a little demon who had a little trap door on the partition, he may be able to let the fast ones through to one side and keep the slow ones on the other. This would create a heat differential that would be capable of driving an engine. This newfound power would only result from a certain kind of informational exchange. In Pynchon's novel, the main character is invited to contact the demon. It is said that by focusing on the machine, some people can make the pistons move a little. The main character tries, but nothing happens.

Maxwell's Demon is an allegory for magic in all of its forms. The hermetic ideal posits a sympathetic universe that is balanced (captured in the phrase "as above, so below"). Action occurs as a result of an imbalance - a differential - the same kind that drives the Stirling engine. Thus, through an act of will or spell, you can get rain, but it will be extra dry somewhere or sometime else. Slavoj Zizek has written about this:
The very notion of man as an "excess" with respect to nature's balanced circuit has finally to be abandoned. The image of nature as a balanced circuit is nothing but a retroactive projection of man. Herein lies the lesson of recent theories of chaos: "nature" is already, in itself, turbulent, imbalanced; it's "rule" is not a well balanced oscillation around some constant point of attraction, but a chaotic dispersion within the limits of what the theory of chaos calls the "strange attractor," a regularity directing chaos itself (Looking Awry, 38).
Thus it is not a balance that makes "nature," but like the Stirling, a motive imbalance. A demon had gotten into the mix. Perhaps Maxwell's demon is the "strange attractor" of chaos theory. In any case, the demon directs the energy in the system such that it throws things out of balance. My mother reminded me yesterday of the explosion in the dalmatian puppy market after the Disney film 101 Dalmatians opened in theaters. The problems was that dalmatians are notoriously difficult dogs, and no one knew how to care for them. This is a relatively minor example of Maxwell's demon at work. In the world of finance capital, these energetic shifts can nearly defy imagination. We know that the words of Alan Greenspan, that strange attractor, can move mountains. I learned recently that the military-staged toppling of the Saddam statue in front of the Palestine Hotel (where the reporters stayed) precipitated a mini-crash on Wall Street. This was due to the resemblance of the event to the images emanating from the collapsing Soviet Bloc.

1 Comments:

Blogger Unknown said...

Thanks for linking to my page:
http://www-personal.umich.edu/~bclee/lens.html

This page has moved to:
http://bclee.net/lens.html

Later this year the University of Michigan will delete all www-personal web pages and those links will stop working. I have 301 redirection set up now, but that will stop working when they delete the pages.

Thanks again!

11:25 AM  

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