Nanotechnologists have now designed and built a disk that can store data for a million years or more. That time frame is almost incomprehensible compared to the current magnetic hard disks that can store data for just over a decade.
Back in 1956, IBM was the first company in the world to introduce a commercial computer capable of storing data on a magnetic disk drive. The IBM 305 RAMAC used fifty 24-inch discs to store up to 5 MB of data. Today, hard drives have no problem storing data with general capacities of 1 TB available on a 3.5-inch disk. Despite this massive increase in storage capacity, things haven’t really changed. The life of data that can be stored on magnetic discs is still approximately 10 years. The question is, how can we preserve information on a timescale greater than that?
Well, Jeroen de Vries at the University of Twente in the Netherlands and colleagues have designed and built a disk capable of storing data over 1 million years. They have performed accelerated ageing tests showing that the disk should be able to store data for 1 million years and maybe longer.
The idea behind accelerating the process of ageing is based around the fact that data must be stored in an energy minimum that is separated from other minima by an energy barrier. So to corrupt data by converting a 0 to a 1, for example, requires enough energy to overcome this barrier. The probability that the system will jump in this way is governed by a principle known as Arrhenius law. This relates the probability of jumping the barrier with factors like temperature and the Boltzmann constant and how often a jump can be made, which is relative to the level of atomic vibrations.
Calculations reveal for data to last a million years, the required energy barrier is 63 KBT or 70 KBT to last a billion years. “These values are well within the range of today’s technology,” say de Vries. To prove this point, the team built a disk capable of storing information for this period of time. The data is stored in the pattern of lines etched into a thin metal disc and then covered with a protective layer. The metal they used was tungsten, which they chose because of its high melting temperature (3,422 degrees C) and low thermal expansion coefficient. The protective layer used is silicon nitride (Si3N4), chosen because of its high resistance to fracture and its low thermal expansion coefficient.
The disk was using standard patterning techniques and stored data in the form of QR codes with lines 100nm wide. The disk was then heated at various temperatures to see how the data would be affected. The results, although carried out in specific laboratory conditions, are impressive. According to Arrhenius law, a disk capable of surviving a million years must survive 1 hour at 445 Kelvin, a test that the new disks passed with no problems. Actually, the disks survived temperatures up to 848 Kelvin, although with major amounts of information loss. That compares well with the Rosetta Project, a proposal by the Long Now Foundation to create archival materials capable of storing data for periods greater than 10,000 years.
This suggests we may to be able to preserve a significant amount of information for future mankind using this technique.
[Image via gizmodo]