Blogging time travel

20 Jun

To avoid discussing the depressing news that the world's dry regions are getting bigger and that British students find science dull and hard, I thought I would devote my Science Monday post to the possibility of time travel.

A new theoretical piece from Austrian and American physicists suggests that time travel, as Einstein predicted, is possible, but that the rules of quantum mechanics solve the problem of the time travelers paradox. As we all know, a central principal of quantum mechanics is that before something is observed we do not know its state. There are an infinate number of possibilities. This is the idea behind Schrodinger's cat. However, once observed we know the state of the object of our observation (i.e. we know if the cat is dead or not) the number of possibilities shrinks to one and there is no uncertainty. According to the physicists new theory of the mechanics of time travel, it will be impossible to change the past because a time traveler will know the state of the present and therefore quantum mechanics will only allow that single outcome to occur.

While an intriguing solution to the time traveler's paradox, it really just transforms the paradox. If you wanted to kill your own father, you could just send a monkey trained to kill your father back in time. Since the monkey will have know knowledge of the present state of your father, he or she could change the past according to this theory. However, what happens if you know the present state of your father? Does that count? Are we safe from temporal assassination as long as someone, somewhere knows our present state of existence? What do you think?

Link: BBC NEWS: New model 'permits time travel'

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