Monday, June 22, 2009

The (Non)persistence of Memory: Part I

In my daily trawl of the internets, two items caught my eye because of how strange and wonderful they were. One comes from the realm of contemporary art, and the other from the realm of physics, but they're remarkably similar. Both have to do with time, and lots of it, so I thought they were worthy of two blog posts. I'll start with the physics.

Ever wonder how future civilizations are going to know about our world? So much of what we say and do is recorded digitally via mediums that become obsolete at an alarming rate. (This website suggests creative uses for old VHS tapes.) On the other hand, the people who carved these symbols on tortoise shells had the right idea—simple and low-tech, with a life span of 8,000 years and counting.

The downside, of course, to these tried and true methods is that you can't fit that much cuneiform on a stone tablet. On the other hand, terabyte drives are affordable and compact. But unlike Mesopotamian tablets, Egyptian papyri, and 10th century bibles, today's hard drives won't stand the test of time. Not only are they physically fragile, you can't guarantee that someone will be able to read them in thirty years, not to mention a thousand. Check out this chilling article from Popular Science on the archival challenges posed by the digital age That's why I'm having my favorite emails carved onto marble slabs.

Luckily for the archaeologists of the future, physicist Alex Zettl and his colleagues at UC Berkeley and Lawrence Berkeley National lab have devised a remarkably simple solution. That not only beats out affordable terabyte drives for data storage density but also, he claims, could preserve data for up to a billion years. Beat that, ancient Sumerians!

The idea is remarkably low-tech, except it's based on those little guys that always seem to make the news—carbon nanotubes. The basic idea is take a one-atom-layer of graphite—the stuff in your no 2 pencil—and wrap it into a cylinder. The resulting tube is less than a 1/50,000 the diameter of a human hair, but can stretch for several millimeters.

Back to our billion-egarian hard drive. To create a bit, Zettle and colleagues inserted an iron nanocrystal into a tube. An electric current causes the speck to shuttle to one end of the tube ("1") or the other ("0"). C arbon nanotubes are some of the most resilient materials in the world, and Zettl says theoretical models show that the little nanocrystal , once placed, will stay put for "in excess of a billion years." These oddly mechanical bits are so tiny, Wired writes, that "you could store data from nearly 25 DVDs in the space of a postage stamp." In contrast, says the LBNL press release, the carvings at the ancient Egyptian temple of karnak store about 2 bits per square inch.

Measuring the resistance of the tube reveals whether the electromechanical bit is a 1 or a 0. So as long as our descendants know about electromagnetism and binary, our data should be accessible to posterity. Great idea, but I can imagine additional difficulties; archaeologists will need a device that quickly reads the resistance of Zettl's drive, and software that converts the binary to my facebook status from June 22, 2040 ("Hanging out with my grandchildren on my yacht. So glad I decided to move to Greenland before global warming really set in.") So far Zettl and company have looked at theoretical models and created individual bits, not an entire hard drive, but the physicist says a working device could be feasible in a couple of years. Authors at Wired and ScienceNow reporting on the advance tellingly complained that they didn't realize their tweets and facebook wall messages were going to last so long.

Stay tuned for tomorrow's post, in which a contemporary artist takes on the short story format with a little help from physics.

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