A post on The Next Web reminds us that the CD is thirty years old this month. As the history there explains, work began back in the 1970s at both Philips and Sony on an optical recording medium for music, which culminated in a joint standard launched in 1982. The key attribute of the compact disc was not so much its small size - although that was the most obvious difference from earlier vinyl - but the fact that it stored music in a digital, rather than analog format.

At the time, that probably seemed a technical detail to most people, but it had two profound consequences. First, it began the shift from a world of analogue music recordings - LPs and tapes - to one that was digital. And secondly, it created the pre-condition for the rise of file sharing in the 1990s once the MP3 compression technology had been devised, and the Internet became available to general users - especially younger ones. Services like Napster would not have been nearly so popular had there not been convenient digital files on CDs just sitting there, waiting to be ripped, uploaded and shared. And the reason it was so easy to do that was because CDs came without any copy protection mechanisms whatsoever.

So how on earth did Philips, Sony and the entire music industry make what must appear in retrospect such a huge blunder? Why did they not worry about people copying files from these new CDs? The answer is very simple: because at the time the CD was launched, there was nothing you could copy a CD to.

One year after the CD's commercial appearance, IBM launched its first version of the PC that had an internal hard disc, the IBM PC XT. Its capacity? A roomy 10 Mbytes. The CD holds around 700 Mbytes, meaning that uncompressed songs typically require around 50 Mbytes of storage each. The cost of any hard disc capable of storing even a single song was so great back in those days, that the idea of digital piracy was self-evidently absurd, since it would have been far cheaper to buy another copy of the CD than a hard disc to store it on.

But what that failed to take into account was the steady and precipitous reduction in the price per Mbyte of hard disc storage that would take place over the next few decades. Today we have reached the point where you can buy a 1 Terabyte hard disc for around $80; that means the cost to store the contents of an entire CD as MP3 files is about $0.005 - and still dropping.

The CD therefore stands as a wonderful symbol of the music industry's inability to see the deeper, underlying trends in technology, and where they would take us. Back then, it meant that nobody was worried about the idea that people would copy digital files from CDs and share them, because they forgot that technology would make possible tomorrow the things that seemed impossible today. Now it means the copyright industries are still trying to preserve unsustainable 20th century business models instead of planning for the incredible technologies we will have in 10, 20 or even 30 years time. They only have to look at the history of the CD and digital piracy to see just how far things can go - and how wrong our current assumptions can be.