The hope: Why be dead forever, when we can just freeze our bodies and reanimate decades later when someone figures out how to revive us?
The reality: The Cryonics Institute and Alcor Life Extension Foundation have already cryo-preserved hundreds of people. But no human "patient" has yet been brought back to life.
What's the deal? The prospect of cryo-preservation has been around since 1962, when Robert Ettinger published a book called "The Prospect of Immortality." It's been popularized in movies like "Vanilla Sky", and the body of baseball great Ted Williams was frozen in 2002.
According to the Cryonics Institute, the process involves "cooling legally-dead people to liquid nitrogen temperature where physical decay essentially stops, in the hope that future technologically advanced scientific procedures will someday be able to revive them." No cryopreserved mammal has been revived, but insects (and something called "vinegar eels") have come back to life. A few types of human tissue, cells, and organs have also been "revived."
But Williams may have to wait a while to swing the bat again. Robert Freitas, senior research fellow at the Institute for Molecular Manufacturing, predicts the first human reanimation won't happen until around 2040 or 2050.