Note: this overlaps with some things I've written before, but I'm thinking of publishing elsewhere. Forgive any repetitiveness.

Whenever I hear someone wax poetic about the mystical powers of crystals, as elaborated in neo-Pagan systems of magic or medicine, I smile and nod, and say "you have no earthly idea how right you are," though they may have a celestial idea or two.

I say "earthly" because I don't believe in the woo-woo power of big, natural quartz rocks to harmonize one's aura. Instead, I agree with them because I've been trained in crystallography, and I know of several breathtakingly practical applications that materials scientists and engineers have found for this discipline. For instance, the fact that quartz crystals lack inversion symmetry makes them piezoelectric, able to transform electrical energy to mechanical work and vice versa. Resonators that slosh energy back and forth between these two forms are available from hobby shops at very low prices. These crystals allow all of your electronics to keep time with one another, maintaining a harmony so exquisite that it would escape even a dog's ear (canine hearing reaches to maybe 0.1 MHz; the 4 GHz quartz clock shown below isn't especially fast for use with a microprocessor).

Speaking of sound, several mystical traditions hold that vibrations or verbalizations are primordial and universal; for instance, that the syllable "om" brought the universe into being. I don't have any evidence for or against that assertion, but I do know that electron-phonon interactions (that is, collisions between particles of electricity and particles of sound) are very important for the workings of semiconductors and superconductors. Your dad's old transistor radio, let alone your doctor's new MRI scanner, wouldn't work without the designers having some very subtle understanding of the properties of sound.

But phonons are really only well-defined within crystalline solids, so maybe that's a spurious example. Even sound in gasses has some surprising applications, though, through the thermoacoustic effect. There's a commercially available system that uses sound to condense natural gas on remote oil wells, for shipment to consumers. Offshore oil rigs, or wells in the middle of a desert or tundra, would otherwise vent or flare the gas they produce, adding a lot of methane or (slightly less bad, from a greenhouse perspective) carbon dioxide into the air without using it to accomplis anything. A thermoacoustic system will burn some small fraction of the gas, and use that heat to generate sound waves, which, in turn, drive a refrigerator that brings the remaining gas to cryogenic temperatures. This reduces the methane's volume by about a thousand times, and allows it to be transported in cheaper equipment designed for liquids, easing demand for synthetic fuel gasses. Why not use a conventional heat engine and mechanical refrigerator, you ask? Well, if it's so remote, a breakdown would be a big problem. Thermoacoustic systems are a lot more reliable, because they have approximately as many working parts as an old-fashioned flute: zero.

Of course, seeing this gas liquefaction technology as a good thing begs the question of whether we should be extracting fossil fuels at all. It's great to save a lot of methane emissions at the expense of a little carbon dioxide, but if we want our global climate to stay at all familiar, we should probably be working to return carbon to the earth, rather than to dig it up more efficiently.

I think there should be a lot more composting, for instance. If something goes into thelandfill and begins to rot, it will largely turn into methane and be released. Efforts are made to capture some fraction of this methane at the most enlightened of dumps, but I'm told that this is only a small help.

Judging by how much weight my compost pile has lost since I set it up, I'm probably emitting more carbon dioxide now than I did a year ago. But that means a lot less methane, and, on top of that benefit, I intend for the carbon that remains to be buried in garden soil, where it will probably stay for quite some time. If it leads to more plant life, it will pull still more carbon from the air.

I try to be thorough about it: food waste, raked leaves, and floor sweepings, of course, but also any paper towels that I use in public restrooms. Unless a paper product is recyclable, or small samples of it burn green (a test for poisonous copper, which many fast-food companies use in their ink), or it's coated in plastic rather than wax, it goes in the compost pile.

Composting has some other benefits, of course. At the risk of sounding like a gullible hippy, I find the act of turning a compost pile to be a powerful meditation on mortality. It adds some much-needed perspective to my life when I can see the things of man, from pizza boxes to my own nail clippings, being digested by the earth. It challenges my notion of permanence, and keeps me humble. Which I need, as much as the next guy.

humble (adj.)

c.1250, from O.Fr. humble, earlier humele, from L. humilis "lowly, humble," lit. "on the ground," from humus "earth."