Storing data indefinitely

14 April 2020

Interview with 

Professor Colin Johnson, Nottingham University

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Our first listener question came in from Paul, who asked "What's the best way to store information, for perpetuity?". Computer science expert Colin Johnson from Nottingham University pondered this one for us...

Colin - It’s difficult to store information so that it can be accessed dozens, hundreds, or thousands of years into the future. I’m sure we’ve all found a piece of paper that has faded after years in the sun, or tried to play an old VHS tape, or found a vinyl record but haven’t got a record player. Even if we etch words into stone, centuries of erosion will render them illegible.

Already, a lot of VHS tapes are unwatchable. CDs and DVDs – once touted as indestructible – might not last our lifetimes. Even if the physical media survive, the machines might not. Some early video games cannot be played any more because the consoles no longer work. Whole media, such as the teletext service that provided text on TVs, are almost lost to history - though there has been some recent success in recovering it from old video tapes.

What about a technology that doesn’t require any hardware, like a printed book? Many books from the nineteenth and twentieth centuries were printed on slightly acidic paper that broke down over many decades, and so since the 1950s books have been printed on acid-free paper that should last 500-1000 years.

But, improving the media that we store information on will only take us so far. If we want to preserve information for the long run, we need to make fresh copies of the information regularly. This is how texts have survived from the ancient world. Physical copies of the works of Ancient Greek playwrights and philosophers haven’t survived to the present day, but their words have been copied and re-copied over the centuries.

This applies to information stored on computers too. Rather than trying to make a disk last forever, instead we can copy it onto a new disk every few years – and don’t encode it in a way that relies on a specific piece of software to play it back.
This gets harder in an era when information is distributed across the Internet. One document might survive, but its links to other documents don’t. In 2017 the Canadian  Supreme Court realised that many of its recent judgements referred to information on websites that had since vanished, and so now a copy of the sites are archived along with the judgement.

What about really long-term storage of information? What if we need to store information that might outlive the English language, or the collapse of civilisation? This is a challenge for scientists who are storing nuclear waste that will be around for millennia. Rather than relying on text, or any kind of culturally-specific image (such as a warning triangle), instead they have to think about the fundamentals of how we communicate ideas, resorting to basic pictograms and thinking about how a civilisation thousands of years hence might interpret – or misinterpret – that message.

So, it depends on how long you want to store it for. To ensure that your grandchildren can read it, a good quality printed book is fine. If you want it to last for millennia, you have a different challenge on your hands!

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