1/2. Science writer Richard Hollingham reveals that much of our past, from analogue sound recordings to digital computer data, is lost owing to deterioration. He uncovers startling news about government data as well as popular rock songs. While a piano recording from the 1930s can be rescued, recent rock classics have fallen victim to "sticky-shed syndrome" and can't be played any more - except for those by the Grateful Dead, as their percussionist Mickey Hart reveals.