While time travel may seem like a phenomenon found only in movies like Back to the Future and The Terminator, science reveals this may not be the case.
According to physicists, real-life time travel can occur within a kind of feedback loop where backward movement is possible, but only in a way that is "complementary" to the present. In other words, people can only go back in time and look around but cannot do anything that would alter the present they left behind.
Debunking the Time Travel Paradox
One of the biggest myths surrounding time travel is the idea that if one goes back in time they could, theoretically, do something to change the present. The new model, which uses the laws of quantum mechanics, tosses that famous paradox out the window.
Clearly the present has never been changed by roguish time-travelers, simply due to the fact that people don't suddenly fade out of existence because a rerun of events has prevented their births. Therefore, time travel is either:
While the former option may seem the most logical, Einstein's general theory of relativity has led physicists to suspect the latter.
Using Einstein's Theory of Relativity
According to Einstein, space-time can curve back on itself, allowing time-travelers to double back and meet the younger versions of themselves. A team of physicists from the United States and Australia claim this situation can only be the case if there are physical restrictions protecting the present from changes in the past.
These restrictions exist because of the weird laws of quantum mechanics, though (traditionally) they don't account for a backward movement in time. Quantum behavior is ruled by probabilities:
Before something has actually been observed, there are many other possibilities regarding its state; however, once its state has been measured, those possibilities are cut down to only one, eliminating all uncertainty.
To put it plainly, quantum mechanics discerns between something that might happen and something that did happen. For example, if someone doesn't know if their father is alive--if there is only a 90 percent chance he is alive--then there is a possibility one can go back in time and kill him. But, if one's father is alive in present time, then there is no chance he can be killed in the past.
Ahh, the mysteries of quantum mechanics ...
BBC News June 17, 2005
Like me, many of you may be interested in the possibility of time travel. I have always been fascinated with this topic and science fiction films about it are some of my favorite ones.
Of course, as someone who already works 80-100 hours a week, and is trying to cut down, I know that if time travel ever did become possible, my "to-do list" would get completely out of control.