On Friday 07 March 2008 20:51:48 Dan Scanlan wrote: > In digital there are no palimpsests of which I am aware. I look > forward to being corrected. I've grown used to falling into the gaping > holes in my belief systems.
The thing about a computer disk is that it's not really all that digital. A '1' bit on the surface (speaking very roughly here) means a little zone where the magnetic polarity runs in one direction; a '0' bit is a zone where the polarity runs in the opposite direction. In principle, when you rewrite a '1' as a '0' (or vice versa) the strength of the magnetic field in its new polarity will be less that when you overwrite a '1' with another '1' (thus reinforcing the previous polarity) -- and vice versa of course. It requires specialized equipment but these variations in the strength of the magnetic domains corresponding to each bit can reveal information about what was there before. _______________________________________________ pen-l mailing list [email protected] https://lists.csuchico.edu/mailman/listinfo/pen-l
