(The SSV Normandy from Bioware's Mass Effect trilogy, is a ship capable of flying at 'Faster-than-light' (FTL) speeds.)
Every few years an article emerges claiming that Time-travel is definitely impossible, followed a few years later by one claiming the contrary. Now, this is expected, science is founded on the premise of falsifiability.
Falsifiability is, when distilled into (slightly less than) layman's terms, the quality of being understood through a series of testable characteristics. For example, if I know that Copper is a conductive material, I can test it and affirm this knowledge. If I believe that it isn't, I can test it, and realise it actually is.
The more things that could be (but aren't) disproved about a theory make the theory stronger. A quick history lesson: the history of the atom - this demonstrates theory built upon theory built upon theory, each one resulting in the disproving of the last.
This is my scientists and theologians argue, they rely on completely different methods (falsifiability is a common argument against circular logic), for example:
Missionary: God exists, and created humanity.
Angry (and hedonistic) mob: Prove it!
Missionary: The Bible says-
Angry mob: Who wrote the Bible?
Missionary: Men, through the guidance of-
Angry mob: God? Well then prove that they wrote it under the influence of your unproven god!
Missionary: The Bible says they did... oh... I see what you're getting at. Quickly, call the Knights Templar!
And THAT's how the crusades happened (the previous statement and conversation were not true or an accurate historical depiction).
"Traveling through hyperspace ain't like dusting crops, boy!"
Anyway... One of the applications of one of Einstein's many works (time dilation, to be precise) permitted time travel (theoretically). If you'll stay with me a bit longer: I'm about to go faster (and slower).
If you travel at a very high speed, leaving from a stationary point (like earth, into orbit), in terms of relativity, time is moving slower for you than it is for the point of origin you took off from.
This, theoretically, means that we could see the ENTIRE KNOWN UNIVERSE, in one lifetime (if a constant acceleration of 1g is maintained at all times). Note that the previous sentence says "see", not "visit and experience", think "going on Safari in a Sports Car".
And now... 'Back to' Time Travel
June, 2011 - A team of Hong Kong Physicists claim to have proved that, in accordance to another of Einstein's theories (not time dilation), nothing moves faster than the speed of light.
Now, this was a bit of a downer for all the sci-fi fans out there. Remember when I said if you "travel at a very high speed"? I meant faster than the speed of light. Which Hong Kong just shot down.
But never fear, 3 months later, some Mancunians claimed the opposite. They said they discovered "sub-atomic particles travelling at "apparently" faster than the speed of light". Jeff Forshaw, professor of particle physics at Britain's Manchester University, explained this meant it would be 'theoretically' possible to send information 'into the past'.
This is by no means a done deal. Many modern minds, Stephen Hawkings among them, have discarded time-travel as poppycock, Hawkings derided it by asking where all the time-traveller tourists were, if it was possible.
CERN's research director Sergio Bertolucci said that if the findings could be repeated, then it may change the way physics is approached.
"When an experiment finds an apparently unbelievable result and can find no artefact of the measurement to account for it, it is normal to invite broader scrutiny....it is good scientific practice," he said in an interview with Fox News (by the way, he's summarising falsifiability).
It's nice to know that 'theoretically' we might have a theory that permits for time travelling, even if only in a highly limited form. For now.
Also, for a bit of fun, check out Hawkings and Einstein battling it out...