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Parrellel Universes

  1. Sep 20, 2003 #1
    As I understand it, there are only so many ways atoms can conbine together, and space is so vast with so many atoms in it that identical earths exsist else where due to probability.

    Question 1. I am confused with the term 'universe'. When I say 'parrellel universe' am I talking about some other dimension, or merely a matter of distance?

    Question 2. Does every choice you make 'split' an identical earth in a parrellel universe? 'Split' meaning, the two earths have been identical untill you decide to drive to work instead of walk. Thus on one earth you walk to work and on the other you drive. These daliy actions relating to the possible combinations of atoms unfolding in all possible arrangments.

    Question 3. If all possible combinations of atoms exsist, it is easy to assume that there exists a world where you have won the lottery or found your soul mate. However, can we also assume that there are worlds where people have evolved differently, into, say, Hobbits? And thus can we assume the The Lord of the Rings is a reality somewhere else? (I use LotR as an example, instead of the classic Matrix plug)

    Question 4. If all possible combinations of atoms exist, then ANY thought that you have is really a glimps into a parrellel universe. But then I say, "But I can think up some weird stuff, like flying pigs and horses that talk." So the question becomes, are there constraints on the possible combinations of atoms? Or is absolutely anything possible?
  2. jcsd
  3. Sep 20, 2003 #2


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    This first question actually states two seperate theories. The Everett interpretation proposes that multiple universes exist in different realities, while other theories have all probabilities taking place in this (infinitely large) universe.

    That is the Everett Interpretation in a nut shell (no offense, Mr Evrett). And as you imply, it is not limitted to just the choices we make, but the possible path of every quark, lepton, and bosson.
  4. Sep 20, 2003 #3


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    I think the confusion arises from science fiction, where parallel universes can mean a number of different things. If the MWI of QM is correct, I believe the multiverse literally is the wave function distributed throughout a 3D volume of space and one dimension of time. As such, alternate universes would not be located parallel to each other, but would be contained in the same volume. But I'm not sure about that interpretation, so someone will have to clarify.

    You may have heard about colliding parallel universes, which is the basis of the new cyclic big bang model. In that scenario, the term universe refers to our 4D spacetime, which is a brane, a fundemental object in M theory. These branes, or universes are literally parallel to each other, but this kind of multiverse has nothing to do with the MWI of quantum theory.
  5. Sep 20, 2003 #4
    Well let us speak of this universe alone.

    Q: Is there enough matter and space in our universe for identical earths (as an example) to occurr? Assuming that the possible combinations of atoms is finite. And if 'yes' what is the difference between a massive universe containing multiple identical earths and a parrellel universe? (as in MWI of QM)

    by the way what does MWI of QM mean exactly?

  6. Sep 21, 2003 #5


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    An infinite universe has an infinite amount of matter, but there is no guarantee you'll find doubles of the earth and people. In spite of what was writen in a recent article of Scientific American, infinite space does not automatically mean an infinite amount of identical earths somewhere.

    But if we were to assume you could have many similar earths by the sheer size of the universe, it is different than the MWI. In the many worlds interpretation of QM, all possible worlds exist within the same wave function. If you were to take a finite universe of a small size, you can still have an infinite number of possible states contained within that small finite volume.
  7. Sep 22, 2003 #6
    I have to disagree, not on scientific grounds, but on logical ones. You see, the mathematical probability of something is directly linked to time. If there is infinite space, then there is infinite time, and thus enough "room" and enough time for the probability of all things (including many/infinite copies of Earth and the current circumstances therein) to become 100%.
  8. Sep 22, 2003 #7


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    I think the argument is that the probability of our exact earth existing in its current state is infinitesimal, and so in infinite space there could still be only one. There have been some discussions about this here and on other boards. I'll see if I can dig up the posts.

    An infinite volume of space does not imply an infinite duration of time.
    Last edited: Sep 22, 2003
  9. Sep 24, 2003 #8


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    But an infinitesimal probability is still a non-zero probability... given infinite 'trials,' any event that occurs with a probability greater than zero (however small the actual value may be) not only can happen, but will happen, infinitely many times over in fact. This is relevant to our discussion, of course, only if we assume infinite space, time, and matter. Throw any of those out the window and all bets are off.
  10. Sep 24, 2003 #9
    But if there is an infinite amount of tiem, then the probability of all occurances becomes 100%, and thus there would have to be many/infinite Earths.

    However, I don't see why an "infinitesimal" probability (unless that means that the probability is -[oo], in which case there couldn't even be one) should be a problem when you have infinite space. After all, no matter how much space you exhaust with non-Earth-like planets, you still have exactly as much space left to fit the Earth-like ones. Besides, if you have infinite matter, than it's supposed to go into an infinite amount of possible configurations, and many/infinite slight variations on our Earth are among those possible configurations.
  11. Sep 24, 2003 #10
    Ah, I see my good buddy hypnagogue has already covered my point very well .
  12. Sep 25, 2003 #11
    First, thank you all for your interest in this topic.

    So, then,

    If we assume that space, matter, and time are infinite...
    cannot one assume that every slight variation of Earth exsist else where? And is only a matter of distance?

    Furthermore, if slight variations of earths exsist, then drastic variations exsist as well. And thus the question becomes, is the fantastic a reality? (given infinite space,matter,&time).
  13. Sep 25, 2003 #12


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    It would appear so, The Hinge. Given infinite time, space, and matter, every possible configuration of matter and energy would occur infinitely many times throughout the universe. Of course, the massive distances involved would pretty much make any explorations of 'other Earths' or 'fantastic Earths' impossible.

    edit: Actually, the above might not be strictly true... we'd probably have to make some extra assumptions, like a more or less random or uniform initial distribution of mass or something of that flavor. There is also the issue of thermodynamic heat death-- if the universe kept expanding, then that would impose a limitation on possible configurations of matter and energy as a function of time. It's not even clear that an expanding universe with infinite matter is a proposition consistent with the known laws of physics. But suffice it to say that there would still be boatloads of weird, unimaginable stuff happening all over the place.

    Someone mentioned the Scientific American article on parallel universes. Well, as always take everything you read with a grain of salt, but I think you'd find it very interesting and informative. The URL is http://www.sciam.com/article.cfm?articleID=000F1EDD-B48A-1E90-8EA5809EC5880000&catID=2
    Last edited: Sep 25, 2003
  14. Sep 25, 2003 #13


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    Here's where it gets difficult. From the Math World website: Infinitesimal is a quantity which yields 0 after the application of some limiting process.

    I think we should bring this question to the math forum, or bring some of the more mathematically inclined posters over to this one.
  15. Sep 25, 2003 #14


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    There is no infinite time. A universe with an infinite volume still begins with a big bang.
  16. Sep 26, 2003 #15
    Infinity can stretch in a single direction. An object set into motion will not come to rest unless it experiences a reaction from another mass.

    IOW, time started, but it's not going to stop unless something makes it stop.

    Yes the infinity makes duplication of matter(and evil uses) much more plausible. Of course I'm not a believer in infinity, so I don't buy it.

    Here's something to consider. If the universe is expanding, how can it be infinite? Expansion implies a beginning and end. If the universe is expanding, it has to have a starting point, and an edge. It must exist within something else. Otherwise we have to conclude that if the universe is infinite, It's not really expanding, just moving around. And if it does have a beginning and an end, what's beyond the edge of the universe? Another form of existence. Too many incongruities. Can't except....hmmmmm
  17. Sep 30, 2003 #16
    I bieleve that to continue this discussion I need from you all the definition of time.

    Maybe more specificly, how are time and change different?
  18. Sep 30, 2003 #17


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    Expanding just means the volume of space in between galaxies increases. The universe as a whole does not get larger if it's infinite. Expansion is a local phenomena and does not describe the universe as a whole.

    It implies a beginning of time, though not necessarily an end.

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