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Non-uniformity of the universe

  1. Jan 2, 2012 #1
    Has there been any proble as to why the universe is non-uniform? All of our physics is based on the assumption that the laws of the universe are the same throughout the universe. But if that really is the case, how is the non-uniformity of the universe explained? I mean, there must be some property of the universe that is not the same throughout the universe which is why the universe is non-uniform.
  2. jcsd
  3. Jan 2, 2012 #2
    I could see it being uniform if there were just one 'big bang'. But there's other bangs going on. Constant contracting and expanding of space and energy. This has been going on since the universe began. Galaxies and solar systems form and collapse all the time. My assumption, would be that the universe would not be uniform for that reason. But I don't have anything to back that up with, so I could be completely wrong.
  4. Jan 2, 2012 #3
    Actually, on the large scale, 500 million light years and greater, the universe is surprisingly uniform.
  5. Jan 3, 2012 #4
    The point is that the OP (with good reason) is assuming that space is isotropic so there would be no reason for their to be asymmetry with the "bangs" as you put them.
  6. Jan 3, 2012 #5
    The Universe is uniform to 1/100000 and can be seen in the CMB. Isotropy and homogeneity are crucial cosmological principles. What evidence is their for non uniformity? Especially on large scales?
  7. Jan 3, 2012 #6
    On small scales non uniformity is quite clear, matter clumps together in to distinct galaxies.
  8. Jan 3, 2012 #7
    Yes non uniformity on smaller scales is obvious. The OP was referring to non-uniformity of the Universe as a whole - and did not specify scales. When looking at the Universe as a whole it is very uniform.
  9. Jan 3, 2012 #8


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    You have this exactly backwards. The universe, as Cosmo Novice has pointed out, is VERY uniform (1 part in 100,000) on large scales.

    It is this uniformity of physical law that has led to the similar formations of galaxies, stars, black holes, etc throughout the universe.
  10. Jan 3, 2012 #9
    true, there are 'similar formations' in the universe. However, the odds of some formations are more likely than others. The odds, over an infinite amount of time, will create a universe full of formations (or 'empty of' if you include distance) whose quantity is related to that possibility.

    If you are judging the make-up, or the uniformity, based on what is inside of the universe, and the similarity of those things, and not on the actual spherical nature of the universe, than the universe will have a clearly skewed difference amongst these 'formations'.
  11. Jan 3, 2012 #10


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    Over an infinite amount of time, there will be almost NO formations in the universe.

    The universe is SPHERICAL ??? You've got to be kidding. Perhaps you think that the observable universe (which IS a sphere) is all there is?
  12. Jan 3, 2012 #11
    I used the term infinite to illustrate what happens with odds when played out over time. Your use of the term infinite takes out the obvious, and puts it in another context, for the sake of argument. If that is your goal, then congrats, you win!

    Clearly I do not need to roll two die an infinite amount of times to know that odds dictate sum of seven will come up. The troll response to that would be, but one event yada yada yada. To which I would reply, yes, but the formations in the universe are not one event. They are vast amounts of events, that have already happened, enough so that we would clearly be able to see a definitive difference of formations based on the odds of them occurring.


    I award you, sir, the troll of the day award. I am sorry if I gave you that indication through the ambiguity of my words. Perchance you do not calculate when a persons words are ambiguous, instead you just choose the most asinine possibility and roll with the troll because it suffices some inner desire to be correct over someone else. Were you often looked down upon when you we in a weak state? Maybe you have some pent up aggression that is just aiming to get out.

    To clarify,

    IF A and Not B than X.

    Not B is, not judging the uniformity on how spherical the universe is.

    Stating Not B does not in any way indicate that I believe B to be true. All that it indicates is that I believe that Not B (or Not the spherical nature of the universe) was somehow being used in the discussion of this thread.

    The OP's post

    First off, I have no clue what a 'proble' is. But when I read this, I was assuming the 'non-uniform' was based on the actual shape of the universe. I pick circle at random because it was a uniform shape.

    Mayhaps (sic), I was wrong to assume that the OP did not want to talk about the shape of the universe, but instead the changes in physics throughout the universe, that somehow have no relation to shape whatsoever, despite being quote unquote 'throughout'.
  13. Jan 3, 2012 #12
    You used sphere, not circle, and additionally a sphere is not a uniform shape. If you are talking about the shape of the Universe in terms of a sphere then there is a misunderstanding somewhere as a Sphere cannot be isotropic by its very nature. An n-Sphere is a different matter entirely.

    The non uniformity that can be seen in the U is very small indeed - as evidenced by the uniformity of the CMB temperature which I mentioned earlier.

    Just to clarify the overall "shape" of the U is unknown, it is entirely dependant on curvature, which has not been measured to an accurate enough degree (possibly the U is so large that the curvature may be impossible to measure globally.) Whether positive, negative or absolutely flat this has no impact on the observed isotropy and would not affect the uniformity of the U.

    I hope this helps and do not wish this discussion to degenerate. If there is anything you are unclear about or wish to discuss further then please respond appropriately - remember this is mainly a scientific community and people are here to help. :smile:
  14. Jan 3, 2012 #13
    ya, my bad. I meant sphere when I said circle.
  15. Jan 4, 2012 #14
    A lot of comes down to "broken symmetry".

    Imagine a ball at the bottom of a bag. Now imagine a stick pushing up the center of the bag. The ball will fall to one side, even though the bag is still symmetric. It turns out that this is a mathematical description of a lot of things.

    It turns out that a lot of things in the universe have math that works like that. You have ice. If you melt the ice you get this gas that looks symmetric, if you cool the ice, it turns out that the lowest energy state is when all of the molecules are aligned so you get ice crystals.

    One other way of thinking about it is imagine a cone that is balanced on its tip. That's the most symmetric state, but it turns out that this symmetric state is unstable so the cone will fall in one direction. It's frequently the case that the most symmetric state is unstable, so the system will "fall" into a state that appears less symmetric.
    Last edited: Jan 4, 2012
  16. Jan 4, 2012 #15
    A lot of it also comes from quantum jitters in the early pre-inflation universe. When the universe expanded what started out as quantum fluctuations in energy density expanded as well, giving rise to gravitational clumping.
  17. Jan 4, 2012 #16
    Yup. Which gets interesting. If you have an upside down cone and everything is *perfectly* still, it will balance, but the slightly nudge will cause it to fall to one side, and quantum mechanics insures that there is some random noise that causes unstable systems to fall to one side or another.

    It gets more cool.... If you have a lot of different cones and then you see how they fall, you might be able to figure something out about the jitter that causes the cone to fall on one direction or another. If you get really lucky, you might possibly figure out something about what happened at the big bang or before the big bang.

    Same sort of thing happens when you drop Mentoes into coca-cola and this is also why you should be careful if you boil water in a microwave. What ends up happening is that you create a system that is mathematically like a cone that is balanced on its tip, and the slightest nudge causes something to go kaboom.
  18. Jan 4, 2012 #17
    Well for the cone example, there must be some force that makes the cone fall to a particular side. If not, the cone would balance itself. Unless there was some mistake when placing the cone on a surface due to which there was a slight force applied to the cone on one side which made the cone fall to a particular side. Either ways there was something that was not the same everywhere and thats my point.
  19. Jan 5, 2012 #18
    I'm sure I heard about the "axis of evil" about this or something.
    Everyone here is pernickety like that (or genuinely thinks you don't understand because you used the wrong terminology). You'll have to get used to it.
  20. Jan 5, 2012 #19
    What if our expansion isn't spherical, and it only looks that way because we are inside the gravitational lens? I think we started out as a jet and are accreting into a disk.

    If you think about it; it would explain varying rates of expansion and exaggerated rotational velocities, thus dark matter and energy. It allows for increasing entropy while the universe cools. It allows for multiple dimensions in between a starting state of one primary dimension and an ending state of primarily 2 dimensions.

    It's all about the tendency for rotational inertias, of every type and dimension caused by the inevitable asymmetries, to align. The presumption that we are in a spherical state expansion ignores that we may be spinning, and that the rate will increase.

    It is very simple. An Occam's razor kind of thing.
  21. Jan 5, 2012 #20


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    Uh ... no ... it's a nonsense kind of thing. You need to read up on the Cosmological Principle.
  22. Jan 5, 2012 #21
    In response to my nonsense, the mass energy of the universe as a whole will always present an image of spherical expansion because of gravitational lensing while we are inside it. Our universe could be accreting, growing cancers, etc. and still appear spherical because of lensing.
  23. Jan 5, 2012 #22


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    I don't believe that gravitational lensing could even begin to work in this way.
  24. Jan 5, 2012 #23
    Gravitational lensing as we see it is a relatively singular point of mass in our learning. We are not taking into account the whole mass of our universe and the effects of being in it. Think of the geometry of Xray reflectors in thermo nuclear designs. All emissions, all effects, and all observations are within a shell of changing shape. All we see as normal is a gravitational lens, and the distant observations that highlight its existence but don't coincide with normal are seen as deviations from something called a principle in local scale.
  25. Jan 6, 2012 #24


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    This is not a mainstream idea and does not belong on PF. I seriously doubt that the effects we observe could be caused by this effect.
  26. Jan 8, 2012 #25
    Prior to the Big Bang, whatever existed was in equilibrium. The Big Bang was caused by a shift in this equilibrium. The non-uniformity of our current system is a reflections of the degree of the disequilibrium. As most posters are pointing out, being that this non-uniformity is relatively small, the initial disequilibrium was relatively small.

    The above begs the question of how you get an endogenous regime change.
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