May 11, 2010
Posted: 01:31 PM ET
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Stephen Hawking's new Discovery Channel series, "Into the Universe," aired again last night and continues into next week. In it, the famed cosmologist discusses the mathematical probability of aliens, the Big Bang and time travel. Hawking's theories on time travel in particular seem fairly optimistic - although "Back to the Future"-style DeLoreans are conspicuously absent. That will be the topic next week. Taking a cue from the show, here are five semi-practical models of time travel:
Barrel through a wormhole
The caveat, of course, is that we'd be facing heavy radiation feedback concerns (a bit like the screeches you hear at rock concerts) and even without that problem, that we would create paradoxes by messing around with historical events in the past. For this reason, Hawking believes travel to the past may well be impossible.
Go near a black hole
Go really, really fast
Live on a space station
Become a Retronaut
Posted by: Nicole Saidi -- CNN iReport Senior Associate Producer
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