More waves today: Collapsing Quantum Wave Functions and their effects on a time traversable universe.

"THE laws of physics seem to permit time travel, and with it, paradoxical situations such as the possibility that people could go back in time to prevent their own birth. But it turns out that such paradoxes may be ruled out by the weirdness inherent in laws of quantum physics.

Some solutions to the equations of Einstein's general theory of relativity lead to situations in which space-time curves back on itself, theoretically allowing travellers to loop back in time and meet younger versions of themselves. Because such time travel sets up paradoxes, many researchers suspect that some physical constraints must make time travel impossible. Now, physicists Daniel Greenberger of the City University of New York and Karl Svozil of the Vienna University of Technology in Austria have shown that the most basic features of quantum theory may ensure that time travellers could never alter the past, even if they are able to go back in time.

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.

Quantum theory allows time travel because nothing prevents the waves from going back in time. 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. "If you travel into the past quantum mechanically, you would only see those alternatives consistent with the world you left behind you," says Greenberger."

When I first read this I was pleased, for several reasons. Forgetting for the moment that actually building a time machine is probably centuries away (if it's possible at all) these new insights into Quantum Wave Functions would seem to allow actually witnessing the past - surely the dream of every historian, anthropologist, archeologist, physicist or Star Trek fan alike - whilst not breaking the rules of cause and effect. The Wave Functions of entities and actions across the timeline are absolutely set to collapse into acceptable areas of probability whether you use your time machine or not... Phew...

I was also reminded though of theories which posit time as equal in dimensionality as space. Quantum Theory gives us a glimpse into a highly chaotic universe where one electron can be in an infinity of places at one time until the atom is positied (consciously measured). The Wave Function of an electron, atom or two-headed cat predicts the likelihood of the precise location of that entity. By plotting the Wave Function one can ascertain the probability the two-headed cat will exist in state A or state B at time C. The article above would suggest that a Wave Function can stretch back into the past, allowing the variable C to be stretched in more than 1 dimension (i.e. not just forward in time).

There is a slightly bizarre theory that says that there is only 1 true mutable atom in the universe and that it exists simulatenously, in an infinity of possible states, along our perceived timeline. Thus everything in the universe in some sense is the same mutable atom perceived at a different state along its Wave Function by the entities who share this universe. Time in this model is the scaffolding supporting the nature of our perception. Our forward moving, gradual time perception draws out that 1 atom into its infinity of possible states. The universe is thus the reflection of all the points one could draw on the Wave Function of that 1 mutable atom - call it the 'God Atom' if you like.

Anyway, there's my brain rolling off on tangents for you. If you find this a bit too much or would just like to read up on it then please click on some of the links above. I can't find a link about the 'God Atom' idea, but will add one later if I come upon a good one... What point of time would you go back too, keeping in mind that you cannot have any effect on the universe around you?

Categories: Science, Time, Perception, Nonsense, Weird, Physics, Philosophy, Future, Quantum Theory

Archived Link