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If you must preserve messages for people in the far future to read, Blu-ray discs and USB sticks are no good.
For real long-term storage, you want a DNA time capsule.Just 1 gram of DNA is theoretically capable of holding 455 exabytes - enough for all the data held by Google, Facebook and every other major tech company, with room to spare. It's also incredibly durable: DNA has been extracted and sequenced from
700,000-year-old horse bones. But conditions have to be right for it to last.
"We know that if you just store it lying around, you lose information," says
Robert Grass of the Swiss Federal Institute of Technology in Zurich. So he and colleagues are working on ways to increase DNA's longevity, with the aim of storing data for thousands or millions of years.
They began by looking at the way information is encoded on a DNA strand. The simplest method treats the DNA bases A and C as a "0" and G and T as a "1". Of course, any damage to the DNA leaves holes in the data, so the team used an error-correcting technique called a Reed-Solomon code. This includes redundant blocks that can be used to reconstruct garbled bits of data.
They also tried to mimic the way fossils keep a DNA sequence intact. Excluding all water from the environment was key, so they encapsulated the DNA in microscopic spheres of glass.
Comment: There just seems to be no way around it; use a cell phone and know that you can be tracked.