Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Many Worlds and the arrow of time

  1. Feb 12, 2010 #1
    I had a couple of interesting thoughts today on the matter of Many Worlds. First is that, in a way, I think the so-called "branching" posited for MWI could be thought of as a derivative of time. For example, time is the derivative of space (i.e. using change in space with respect to time)... then branching is kind of exponential (infinite?) change with respect to both space and time. I can't think of a good way to represent this idea other than to say if space-time is a square, then space-time-branching is a cube. Or perhaps, branching is "every" space-time that's possible.

    Which brings the next idea... that if this branching is indeed occurring, then that would force time to move forward only. My reasoning is that with each quantum moment, these branches continue "expanding" and branching more. Let's suppose that I decide to go back in time... I can't unless "me" in all of the associated branches also decide to go back in time. Because "me" has logically consistent choices that involve not going back in time, we know that some of them won't. Therefore, none of them actually could. Therefore, time can only go forward. The only exception would be if there were some way to eliminate the logical possibility of moving forward in time, which would force time to either stop, or move backward. The other, slight, possibility is that you could move backward in time, but that it would be imperceptible as the movement would be "complete" in that it would reverse all memories, knowledge, and information - as if you had never moved forward in time.
  2. jcsd
  3. Feb 12, 2010 #2
    no, there is nothing special in MWI with arrow of time.
    You should look at it from 'birds's view' - looking at the Universe Wavefunction.
    From that point of view, there is no 'branching' (the definition of branching is quite fuzzy: it is studied by Quantum Decoherence, but QD uses some basis, hence, it uses some frog's (observer) perspective).
  4. Feb 13, 2010 #3
    MWI gives 'birth' to complete histories, and nothing about a QM Interpretation can be useful if it contradicts basic tenants of QM.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook