Scientists in the UK and the Netherlands have just demonstrated technology that one day might preserve data for up to a million years. The medium is a glass ‘memory crystal,’ a storage technique that uses a laser to alter the optical properties of fused quartz. The scientists say that such a memory crystal could have the capacity to store 360 terabytes of data – the equivalent of 75,000 DVDs. But of course, while such an advanced technology solves one problem (keeping information secure for eons), it raises another, possibly even dicier one: in a million years will anyone (assuming humans are still around) be able to retrieve the information and if they do (whoever ‘they’ are), will they be able to understand it? Several years ago a similar problem arose when Yucca Mountain in Nevada was considered as a possible storage site for radioactive waste (plans have been delayed because of vehement opposition to the idea). Scientists believed that the waste could be stored safely for ten thousand years, but how, they wondered, would they be able to caution people (again assuming that there will be people) about the potential danger of contamination? In ten thousand years – or five or three or one thousand – anyone who still calls Earth his or her home might not be able to comprehend any language now in use. So scientists debated whether some kind of sign or image could be devised that would carry a warning across the centuries. There was, as far as I know, no agreement about what such a sign would consist of. NASA scientists grappled with a similar dilemma on a cosmic scale when in 1977 the Voyager 1 spacecraft was ready to be launched. In the unlikely event that Voyager 1 was ever intercepted by extraterrestrials, scientists felt that they should pack it with artifacts that would represent the best of human civilization. (No photos of genocide victims or films of Congressional debates.) So they put on board an assortment of images, a tutorial about the nature of the solar system and the planets, a description of fundamental mathematical and physical laws, as well as an explanation of DNA, some basics about human anatomy and reproduction along with lots of illustrations of animals, insects, plants and landscapes. There was also a depiction of a naked man and woman so that the little green men would know what they’re up against should they consider an invasion of our planet. To give the curious aliens a deeper understanding of our culture the scientists also included a selection of music ranging from Beethoven and Stravinsky to Blind Willie Johnson and Chuck Berry. Now more than 11 billion miles from Earth, the spacecraft has recently entered a kind of border region – called the heliosheath – separating our solar system from interstellar space. So far, though, there’s no indication that aliens, if they’re out there, have taken any interest in the Voyager as it hurtles inexorably into outer space. And what if the aliens do get hold of the contents of the Voyager and can’t make heads or tails out of it? I suspect that we’ll never know because at some point the spacecraft will lose its ability to communicate with us down here on Earth.