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Physics laws.

  1. Jul 14, 2010 #1
    Well, I was a little high with a classmate when we were wondering the wonders of this cosmos, watching "Into the Universe with Stephen Hawking", the alien chapter, where it told about concepts of alien life in exoplanets. So we thought about concepts of "Exouniverses". I use this term because:

    can we model or predict (through mathematical models) universes with different physical constants?. I mean, considering a universe where the mass of neutrons, protons or electrons are different,the amount of matter vs antimatter or where speed of light is different (for example).

    Basically, as we make astrobiological or astrometeorological models, can we make cosmoligcal predictions or are we unable to do it because this "Theoricals Universes" are unimaginable.

    "Unimaginable" sounds ambiguous if we talk about relativity or quantum physics, I know, but let's think about this concept.
  2. jcsd
  3. Jul 14, 2010 #2
    I think the concept of infinite universes is baffling, did you know, there is another universe
    were everything since the beginning of time has been exactly the same except in the other one, I didn't post this, and another one, I did post this, but I have rocket shoes on.
  4. Jul 15, 2010 #3


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    One could conceivably imagine some brane-collision model or some other such nonsense which results in a "prediction", if you will, for the various constants of nature based on the geometry of the brane collision (or some other suitable parameters specific to the universe generation). The problem is, this information is entirely useless. It doesn't allow us to actually test anything, since we cannot go back in time and somehow observe the branes that collided to produce our universe and verify that indeed they had the configuration we assume they did. Nor does it allow us to predict in the future any values for other universes, since by construction these are disconnected from us.

    Moral of the story is that such predictions are 99.99(repeat indefinitely)% useless, so it's probably not even worth considering.
  5. Jul 15, 2010 #4


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    Agreed, nabeshin. Mathematical elegance does not lend credibility to inherently untestable hypotheses. Not everything mathematically possible is observationally represented in our universe. Math unveils possibilities, not reality.
  6. Jul 15, 2010 #5
    The short answer is: Yes, such universes can be explored for their implications. The annoying aspect of that is that there's currently no evidence for other Universes. The LHC might be able to produce particles predicted by some extra Universe theories, so for now we have to just wait and see.

    A good exploration of how physics changing affects important things like stars is a recent paper by Fred Adams...

    Stars In Other Universes: Stellar structure with different fundamental constants

    ...well worth a read to educate yourself further on the issues involved.
  7. Jul 15, 2010 #6
    Very interesting topic of discussion. I have spent some time pondering the idea that the current values of physical constants are just one stable configuration among many.

    “What if the quantum fluctuations (and other craziness) during the big bang were slightly different and the constants ‘arranged themselves’ into a different stable configuration. This might lead to a completely different set of laws; laws of which we cannot conceive. But here’s an unsettling observation: If the mass of the electron is changed by even a miniscule amount, it will spell disaster for our current stable configuration. But perhaps this one small change will lead to a “shuffling” of laws in which the universe will ultimately settle into stability…”

    …and so forth and so on.

    If one were able to assign different constants to natural phenomena that indeed leads to a stable configuration (and prove it, to boot!), I feel it’s safe to say that he/she will secure their place in the history books.

    What a fantastic thing to ponder!

    EDIT: Oops, the link in the post above me seems to point in the same direction of my post. Now I feel redundant =)
    Last edited: Jul 15, 2010
  8. Jul 17, 2010 #7
    The idea of a "stable" universe is only stable as far as being able to support life as we know it, right? Still, even if a universe couldn't support life, it could still have very strange and active phenomena going on in it.

    What if the electromagnetic force was 10 trillion times stronger, for example? What would the universe look like today? Would there still be things like spiral galaxies, would there be very different structures, or no structures at all?
  9. Jul 17, 2010 #8
    What do you mean with stronger electromagnetic forces? could you give a measurable example? If we consider that energy is a constant in the universe, that example would implicate less matter and gravitational forces obviously.
  10. Jul 17, 2010 #9
    I'm not sure what you're getting at. I'm talking about the relative strength of the forces. The electromagnetic force is already 1E+36 times stronger than gravity, but what if it was even stronger?

    All I can think of for starters is that molecular bonds would be stronger, so larger structures like planets would be able to form, but I'm probably missing something pretty big.
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