Like most, my personal requirements for long-term data storage pretty much end when I end. So, we're talking decades, and certainly not centuries or millennia. I'd even say that the vast majority of things I store on my own hard-drives and various cloud servers don't need to persist in the digital world past a month. There's probably something instructive in that, but whatever: We'd just forget about it anyway.
I'm not exactly the target market for "5D" memory, a technology that's been in the works for several years at the Optoelectronics Research Centre at the University of Southampton which promises all but eternal data backup. The storage scheme is based on tiny quartz discs, each one offering some 360 terabytes of data, along with resistances to heat up to 1000 degrees Celsius and data retention on the order of several billion years. Which is a very long time.
As noted in IEEE Spectrum, the Southampton group has been working on the technology since at least 2011, when it published a paper describing a crystal material that could be used to polarize beams of light into trippy vortex arrangements. Tuning that polarization could be accomplished by patterning nanoscale structures onto the material, and it's these structures that wind up physically representing the stored data.
Now, the researchers have succeeded in building a prototype of their new storage technology, as presented last week at a conference on laser-based micro- and nano-processing. So far they've encoded the Bible, Magna Carta, the UN Declaration of Human Rights, and Isaac Newton’s Opticks, all onto indestructible 5D quartz.
The 5D name indeed corresponds to five dimensions and it's the extra two that are at the root of the new storage scheme. They correspond to "slow axis orientation" and "strength of retardance," both properties having to do with how the refractive indices of some materials change depending on the polarization of light traveling through them, e.g. their birefringence. Data is encoded as combinations of the three spatial dimensions plus the two extra birefringence dimensions. ("Dimension" here [and everywhere else really] can be taken to mean a changing variable corresponding to a measurable physical quantity.)
This is realized by patterning three layers within the quartz via extremely short and intense laser pulses (femtosecond lasers), with each layer of nanostructur ed dots separated from the next by only about a millionth of a meter. This infinitesimal sandwich is what allows for the encoding of information onto beams of incoming light that can then be decoded using a microscope and polariser after it passes through the material.
Eternal data storage is a cool enough idea, but it remains pretty difficult to accomplish, requiring relatively long read/write times, microscopes, and complicated algorithms. The possibility is there, however, and the Southampton group's leader, Peter Kazansky, seems happy enough about that in itself: “At the moment, my personal interest in the direction of saving everything forever if possible,” he told Spectrum.
“I hope we will manage finally to solve the problem of the speed," Kazansky said. "Then obviously bigger markets will open.”