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Parallel Universe Question

  1. Feb 13, 2008 #1
    Greetings Mirthlings,

    I am new to the forum. And I am a layperson. But I am currently reading all that I can get on certain areas of physics so that I can understand better, on a lay-level what I need to know.

    What area branch of physics, do you think, would best explain the existence of a parallel universe that a person could actually exist in? From what I understand so far there could be:

    1. Wormholes to other universes that exist in parallel?

    2. Under the MWI model, alternate physical realities that are worlds that have evolved along a different path than ours. But do these exist in the same spatial location as ours but in parallel because of some property that keeps them separate? Or are they stacked in adjacent branes?

    I was reading that, in string theory, that the smallest bits of matter contain tiny vibrating strings. And the rates at which these strings vibrate (can) dictate the properties of the matter. I've also read that it has been theorized that a parallel world could exist millimeters away from our own. Is it possible or remotely plausible that the strings in matter in a parallel world could be vibrating at a different range of frequencies making that matter present, close to us, but invisible and out of touch for us? Matter that is slightly out of phase with our own?

    I apologize in advance for sounding idiotic. I am just trying to get my head around a theoretically plausible explanation for the possibility of an alternate world, and possibly getting there. I hope I am not wasting anyone's time. Any information or conjecture or references you can provide would be wonderful!

  2. jcsd
  3. Feb 13, 2008 #2
    I promise you, you aren't wasting anyone's time! These are perfectly valid questions. We may know very little about the answers, but they are still valid questions. First, if you haven't already read Brian Greene's book, The Elegant Universe, you should definately read it. Wormholes would certainly be way of verifying the existance of parallel worlds, but the thing is, nobody knows for sure if wormholes even exist. I am not sure how to answer your question about whether these universes would be in the same spatial location as our own. I don't think that they would be in the same location, but don't quote me on that. I'm pretty sure that they would be in adjacent branes. But keep in mind, just because they are in adjacent branes doesn't mean that there is space in between them. Once you leave our universe, space and time cease to have any meaning (unless of course, you enter another universe that contains space and time). I'm really not sure what you are asking about the whole thing with string theory. Could you please rephrase that? Don't feel bad for asking these questions. I wonder about them all the time as well. Some have suggested that there are an infinite number of universes/parallel worlds, each with different laws of physics. Wouldn't it be wild if we could scientifically discover a world where the laws of physics could be broken. Think of the possibilities! Of course, I'm just thinking aloud, I don't really know if this is possible.
  4. Feb 13, 2008 #3
    My understanding is that although some writers habitually refer to the alternate worlds of MWI as "parallel dimensions", these alternate worlds are *NOT* located in physical dimensions or in fact "parallel" to our reality geometrically in the same sense as something like a brane. Rather, as far as I understand things the different MWI worlds are "located" in the wavefunction of the universe. In fact the Many Worlds Interpretation was originally named the "Universal Wavefunction Theory" when Everett proposed it.

    Since these worlds are not physical "places" but rather are superposition states of a wavefunction, it does not seem right to say that these "alternate universes" could be connected by wormholes. (Although who knows, supposedly there's plenty of room for incredibly weird stuff to be happening in the quantum gravity realm!)

    I don't know enough about string theory to attempt your other questions.
  5. Feb 13, 2008 #4
    Thank you for humoring my questions.

    I watched the Nova special "Elegant Universe" and it was really interesting. I will probably watch it again (and again :-)).

    My string theory question was in reference to what I learned from that show. I believe he asserted in that program that the smallest particles of matter are composed of many "strings" of material that are vibrating. And that the rate of vibration is variable and could, in theory (of course) determine the properties of the particle. So.. different particle types would have differing compositions of vibrating strings within them.

    And I had this far fetched notion that, perhaps, the rate of vibration of the strings containd within these particles might determine which universe or "brane" they are accessible from? Maybe the vibrational frequencies of strings can occupy ranges like radio frequencies. Maybe all the "AM" frequencies would compose one "world" but if you flip the button over to "FM" you might see a whole nother world with particles whose strings are vibrating at a different frequency. I realize its a bad analogy because AM and FM are really modulating frequency and amplitude. But I am hoping you are getting my idea.

    That was sort of what I was getting at. And I have no idea what I am talkng about. But based on the limited description of strings and particles in the Nova program I had that as an intuitive notion.

  6. Feb 16, 2008 #5
    Hi Calvin

    I think this qualifies as a thought. One big theoretical problem about flipping into another brane is that since fundamental particle properties and physics laws change, our existance as living organisms would cease. Makes the trip to the parallel universe hardly worth the trouble.

    There is a published theory out there concerning the notion that our particular universe has physical laws that are uniquely suitable for formation of galaxies, planets, and life. In that theory we find ourselves inhabiting this brane not by accident, but by necessity.
  7. Feb 17, 2008 #6
    Thanks for the thought :-)

    I can accept that the laws might be different in an adjacent brane. But is it a gurantee that the laws would the so different as to not sustain our form of life? Couldn't it be equally probable that the laws might be the same or similar? Maybe the laws of physics across branes appear as shades and change with greater degree the further away you travel?
  8. Feb 18, 2008 #7
    Well, you have a point there. But I am having trouble with the idea of visiting, or communicating with, an adjacent brane with, let us say, a string vibrating at a different frequency than in ours. I mean, that is about as fundamental a change as you can get. It would have to make life as we know it impossible.

    Here is my reasoning. Imagine suddenly finding yourself in a universe exactly the same as ours except that the nucleic acid thymidine was unstable and degenerated into free radicals. Such a small incremental difference, but now your DNA is destroyed.

    Now instead of that the difference was more fundamental, like Hydrogen stopped bonding with anions. Now you are really hurting.

    The more fundamental the laws of physics change, the less likely the universe would consist of anything useful to us. And you are talking about strings.

    Now of course, to be fair, it could work the other way. Some other brane might have a better set of physical laws than we have. Have any mathematicians in the string world ever explored that?
    Last edited: Feb 18, 2008
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