This week the Naked Scientists go virtual! We'll be hearing how a new computer system can accurately gauge your age from a mugshot, we come face to face with the painting fool, a computer that can read - and then paint - your emotions, and we find out what's still lurking on your hard disc, even after you think you've wiped it. We also unveil Second Naked Scientists - our home in Second Life - and get stuck into a new molecular glue designed to replaces surgical stitches and staples. Plus, in Kitchen Science, Ben and Dave embark on a far from fruitless mission to charge an MP3 player with an orange...
Deletion of a hard drive does nothing. It is the overwriting of the hard drive that actually physically removes the data. There is some talk that one can still detect residual signals from the original data even when new data has been written over it, but I would have thought that even if you could technically detect some residual signal, trying to seperate the residual signal from the new data that you have overwritten it with would be next to impossible.
Graham and I did discuss the chance that data could be recovered after just one overwrite, due to a 'magnetic resonance' effect which may indicate what position each bit had previously been in. Sadly, we had to remove this from the interview due to time constraints.
Blimey, that's a shock. Thanks for that bombshell Ben; I'd never have believed it.
In the Computer Forensics part of the show, it seemed (to me)to be implied that erasing your hard drive just once was good enough to prevent people recovering your data. If I heard right, then that is false. You need to erase the drive multiple times to even stand a chance.