Vanishing act, the DiscoVery files

Computers have made it virtually impossible to leave the past behind. College Facebook posts or pictures can resurface during a job interview. A lost cell phone can expose personal photos or text messages. A legal investigation can subpoena the entire contents of a home or work computer, uncovering incriminating, inconvenient or just embarrassing details from the past.

The University of Washington has developed a way to make such information expire. After a set time period, electronic communications such as e-mail, Facebook posts and chat messages would automatically selfdestruct, becoming irretrievable from all Web sites, inboxes, outboxes, backup sites and home computers. Not even the sender could retrieve them.

"If you care about privacy, the Internet today is a very scary place," said UW computer scientist Tadayoshi Kohno. "If people understood the implications of where and how their e-mail is stored, they might be more careful or not use it as often."

The team of UW computer scientists developed a prototype system called Vanish that can place a time limit on text uploaded to any Web service through a Web browser. After a set time text written using Vanish will, in essence, self-destruct.