memory under freeze

...Saswata has kept a hard disk inside a freeze to retrive data from it :D, First time i had laughed like this. Although he is famous for humourus activities but this time i was fooled as i found people have found it as a good technique for retriveing data from the "failed" hard disk. So just take the HD and keep it inside a freeze for couple of hr. and fix it back, if you are lucky then you'll get your data back. Sounds like a cool trick. May be Semiconductor guys can put some light on it, and from materials scienctist point of view its really interesting.