Time is a strange thing. There is no law in physics that prohibits time from going backwards, but as we all know, it has a tendency to go always forward:)). Why is it so? We can all envisage the problems that time travel would create: people could go back in time and kill their grandparents, and give past generations modern technology or prevent some historic event from happening!
Physicists Daniel Greenberger of the City University of New York and Karl Svozil of the Vienna University of Technology in Austria have come up with a provocative idea:), but it suggests that time travel might not be possible at all:(.
Worm Hole (Courtesy: ThinkQuest)
Then how are the time paradoxes resolved? According to the new proposal, such paradoxes may be ruled out by the weirdness inherent in laws of quantum physics. The constraint arises from a quantum object's ability to behave like a wave. Quantum objects split their existence into multiple component waves, each following a distinct path through space-time. Ultimately, an object is usually most likely to end up in places where its component waves recombine, or "interfere", constructively, with the peaks and troughs of the waves lined up, say. The object is unlikely to be in places where the components interfere destructively, and cancel each other out.
When Greenberger and Svozil analysed what happens when these component waves flow into the past, they found that the paradoxes implied by Einstein's equations never arise. Waves that travel back in time interfere destructively, thus preventing anything from happening differently from that which has already taken place:)).
So, it seems that even if matter could travel back in time, it will not be able to keep its cohesion, and therefore no information can be sent back in time to influence the past!
Physicists Daniel Greenberger of the City University of New York and Karl Svozil of the Vienna University of Technology in Austria have come up with a provocative idea:), but it suggests that time travel might not be possible at all:(.
Worm Hole (Courtesy: ThinkQuest)
Then how are the time paradoxes resolved? According to the new proposal, such paradoxes may be ruled out by the weirdness inherent in laws of quantum physics. The constraint arises from a quantum object's ability to behave like a wave. Quantum objects split their existence into multiple component waves, each following a distinct path through space-time. Ultimately, an object is usually most likely to end up in places where its component waves recombine, or "interfere", constructively, with the peaks and troughs of the waves lined up, say. The object is unlikely to be in places where the components interfere destructively, and cancel each other out.
When Greenberger and Svozil analysed what happens when these component waves flow into the past, they found that the paradoxes implied by Einstein's equations never arise. Waves that travel back in time interfere destructively, thus preventing anything from happening differently from that which has already taken place:)).
So, it seems that even if matter could travel back in time, it will not be able to keep its cohesion, and therefore no information can be sent back in time to influence the past!
No Time Travel?
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4 Comments:
A consistent theme is that of time travel.
Since I've not always had access to theoretical physics discussing the theme, I've had to work most of the problems out for myself.
So things like retroactive suicide are an obvious no-no, as are making any physical contact with your former self, which is probably in line with the ideas put forward in your post.
But surely these quantum waves cannot permeate all of space-time?
I'd imagine time travel being possible, but requiring the traveller to move to more distant locations to avoid such conflicts...
The only thing that should not be possible is going back in time and changing the history, as that violates causality. Anothing else (like going to the future, and never coming back) should be possible (and is indeed theoretically possible, if one could find ways to travel close to speed of light).
Quantum waves are not waves in real space. So they might permeate space-time, but not actually be detectable unless they collapse. So in that sense, an uncollapsed quantum field is not detectable, as it is a theoretical construct that works, but scientists are not yet sure how or why!
Actually .. No!
If I did that, they'd be public domain, and I've my work cut out making any money from them...
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