The danger of the digital dark age

The man described as one of the fathers of the internet has said that he is worried that all the pictures, videos and documents saved on computers will be lost forever as hardware and software become obsolete. Vint Cerf -- who is now one of Google's Vice-Presidents -- fears future generations will have little record or no record of the 21st century as we enter what he describes as a digital dark age. The BBC's science correspondent, Pallab Ghosh, reports for the Today programme and the World Service from Silicon Valley in California