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One of Many

Posted by michael on from the too-many-to-count dept.

sam_handelman writes "The nytimes has another astrophysics article up. Free subscription etc. It talks about how inflation predicts multiple universes, this week. Dennis Overbye wrote the article, which is nice if lightweight. More info on the theory of inflation. Inflation, which is harebrained on first examination, actually predicts stuff, giving it credibility. Want to be the Right Pinky of God? It may yet be possible."

8 of 196 comments (clear)

  1. Inflation != Multiple Universes by c_de_bugger · · Score: 3, Interesting

    From the article.
    In fact, Dr. Guth said, "Inflation pretty much forces the idea of multiple universes upon us."
    I read the article. Can anyone see where he justifies this statement with anything resembling logic?
    I accept inflation and the 'anthropic principle' as well argued theories. Inflation=multiple universes is not (or not here).

    1. Re:Inflation != Multiple Universes by guybarr · · Score: 3, Interesting

      but this would mean that the laws of physics would no longer be laws ..

      It certainly, IMHO, means that the laws we know break. Very probably it means the laws we can conceivably test also do not apply.

      This does not mean there isn't any generalization of the basic theories which do apply. In fact physicists predict properties such a theory must have, which may lead to hypothesis of this kind.

      wether such hypothesis are true, or can even be tested, again, is a leap of faith IMHO.

      If I lived on a proto-planet then I would be a creature that was much smaller than an electron and therefore must be made up of things that don't apply to the current physics

      Here I think you may have a misconception of the notion of size. General Relativity tells us you cannot directly compare sizes over great distances. This means that the world we live in is a Riemann manifold ( a patchwork of local non congruent euclidian approximations )

      What all this means, is that comparing sizes inside a black hole (the above approximations break on the way) and outside is not only impossible, it is meaningless. It does NOT mean the laws of physics must be different in flat areas inside. (or that they aren't)

      Besides... I'd would be darn horrible to find out that we have been preforming planicide on entire civilizations and races every time a cyclotron or particle accelerator is fired up

      wrong. this may have conceivably been possible if current experiments would heve been close to the plank scale. However we're many many orders of magnitude away from achieving such cataclysmic energies.
      AFAIK we know pretty well the basics of what is happening in the sub-TeV scale.

      --
      Working for necessity's mother.
  2. Multiple universes? by mccalli · · Score: 3, Interesting
    it talks about how inflation predicts multiple universes

    This is one of my pet hates. By the very definition of the word, there can only be one universe. Or are the definitions now being changed?

    Cheers,
    Ian

    1. Re:Multiple universes? by mccalli · · Score: 3, Interesting
      Not a single one of the five different senses of the word gives even the suggestion that there can not be more than one.

      1 : the whole body of things and phenomena observed or postulated

      ie. everything. Can't have more than one of those. If more 'things' are being postulated that match what previously we called the universe, then by definition they are subsumed into the current universe and we need a different word to describe what we used to have.

      Cheers,
      Ian

    2. Re:Multiple universes? by Alsee · · Score: 3, Interesting

      1 : the whole body of things and phenomena observed or postulated

      And then of course there is everything that has NOT been observed or postulated. So that usage does clearly imply that "universe" is not "everything".

      Including everything "postulated" is not a requirement of all usages of the word. In most cases it is a pretty poor usage. You usualy don't want to consider non-existant things that have been postulated to be part of the universe.

      In this case we are talking about something that has been postulated but not observed. It is not part of our universe because it can never be observed. It is part of a seperate whole.

      Considering all of the "universes" to all be part of one universe is A valid usage, but it is not the only one.

      The different senses listed pretty much revolve a "whole body" of things that are in some way connected. If there is a second "whole body" of things that are connected with each other, and there is no connection between the two "whole bodies", then they can be reasonably be called two universes.

      -

      --
      - - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
  3. Re: You've got it backwards. by guybarr · · Score: 5, Interesting

    Unfortunately, the big-brained ones have now copped onto the Sci-Fi idea of these alternate universes

    I think you have a wrong picture: although the notion of different choices and their consequences is an ancient one, the notion of parallel universes came from science (everett interpretation, feynman-multiple-path approach to quantum mechanics) to SciFi and philosophy.

    As usual, the ideas flow from science to science-fiction. I asume this is because usually, nature is more bizare than what our imagination can predict. (and also because the best scientists are among the most creative people ...)

    --
    Working for necessity's mother.
  4. Infinite universes?... by Anonymous Coward · · Score: 3, Interesting

    If there were an infinite number of universes in which each and every chance outcome is played out, would there be a universe where someone invents a universe destroying machine and destroys all the other universes without being stopped by anyone?

  5. More ambitious multiverses by SiliconEntity · · Score: 3, Interesting
    Max "Mad Max" Tegmark has a more ambitious multiverse theory. It goes way beyond inflation, black holes, and even the Many Worlds Interpretation of quantum mechanics.

    His idea is that all possible mathematical structures exist, and that we live in one of them! At some level, physics can be considered a branch of mathematics. Hence our universe can be considered as an enormously complicated mathematical structure. The question is, why this structure instead of some other?

    His answer is that all mathematical structures exist, but that most of them are unsuitable for life. The paper linked above analyzes many different possibilities in terms of numbers of dimensions, numbers of time dimensions (yes, you could conceive of a universe with two-dimensional time), various other parameters, and he shows that structures that we would think of as living would have a hard time existing in universes much different from our own.

    The Tegmark model can be thought of as the simplest possible physical theory. If physics is reducible to mathematics, then saying that all mathematical structures exist can be put more simply: Everything exists.

    A similar model based on computation is proposed by Juergen Schmidhuber. Rather than Tegmark's mathematical structures, Schmidhuber proposes that all computations exist. Given that any mathematical model of a universe can be simulated by a computer program, these two formulations are roughly equivalent.

    But Schmidhuber's approach has the advantage that it provides a natural way to say that some universes are more probable than others: namely, universes with short programs have more "measure" than universes with long programs. It follows that our universe probably has a relatively short program, which therefore explains why we observe that physical laws are mathematically simple.

    It's pretty heavy stuff, but certainly exciting to see that researchers are (somewhat reluctantly) beginning to entertain multiverse models. The more ambitious "everything exists" theories are still too extreme for the mainstream, but I suspect that they, too, will get increasing attention over the next few decades.