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Flat visible universe

  1. Sep 28, 2013 #1
    So the observable universe is flat overall but warped (compressed) in locations of gravitational fields. Is it the expansion of space which counteracts the gravitational warping thereby making it flat on average?
    Last edited: Sep 28, 2013
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  3. Sep 28, 2013 #2


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    The length scales for which the local inhomogeneities in curvature are non-negligible are orders of magnitude smaller than the length scales involved in the Friedman model of the universe. It doesn't have anything to do with expansion per say; you can have a non-flat universe which is expanding.
  4. Sep 28, 2013 #3


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    A flat universe is like a flat table. When you get right down to it, the table has all sorts of tiny scratches and imperfections, and is really bumpy if you look at its atoms with an electron microscope. But you can still think of it as flat.

    When cosmologists are talking about a flat universe, they're talking about it in the same sense as that flat table. They're just ignoring the little details like galaxies that don't matter on the scales they're talking about in the same way you can happily ignore sub-microscopic scratches on a table.

    Edit: Or what WannabeNewton said.
  5. Sep 28, 2013 #4


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    So is the curvature due to local masses the same "type" of curvature as the universe has as a whole? I don't know if that question makes sense, as I'm not sure how to ask it.
  6. Sep 28, 2013 #5


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    When we speak of the curvature of the universe we are talking about spatial curvature relative to a special family of observers (the CMB frame) so no it isn't the same "type" although I should tell you that the question of "types" of curvature, in the sense of space-time curvature, is already well established: http://en.wikipedia.org/wiki/Petrov_classification
  7. Sep 28, 2013 #6


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    Oh, wow. That's complicated. Thanks WBN.
  8. Sep 30, 2013 #7


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    No. Quite the opposite, really. Through most of the history of the universe, the expansion acted to enhance any large-scale spatial curvature. The recent dark energy-dominated expansion acts in the opposite direction, but hasn't gone on long enough to significantly flatten our universe. Overall, the amount of spatial curvature has increased by a factor of about 500 since the CMB was emitted (very roughly-speaking), and by thousands more since the first atomic nuclei formed.

    And yet, the spatial curvature is still extremely flat. This basically means that our universe had to start out exceedingly flat, because any small amount of spatial curvature would have amplified (dramatically) over time. One explanation for this is inflation, which, rather like the current dark energy-dominated expansion, works in the other direction and suppresses flatness. If inflation lasted long enough, we would never be able to measure any average spatial curvature to our visible universe.
  9. Sep 30, 2013 #8
    I would take the view that the initial growth is expanding faster as it is not reacting against any gravitational field, the energy left behind which makes the universes will be compacted as the energy is used up, this almost certainly cause flattening by gravitational effects and once the localised energy is used up then the mass will collapse in on itself.
    The energy left behind the outer layer energy of growth is continually feeding energy back into the universe by its speed and is omitting more energy than when the Big Bang happened, the mass of energy is growing but the expansion rate is such that older galaxies will no longer be fed this energy as it's gravitational pull is too far away to harness this energy.
    As the rate of growth must be above the speed of light otherwise the universe would contract, with the constant growth and energy supply it would be generate what appears to be constant universe.

    What ever is expanding the universe it is creating energy photons which is creating hydrogen and helium.

    The constant radiation noise may not be from the Big Bang but from the continual growth of the universe as it is the same energy.

    The inter change of growth is constantly expanding, the inter reactions of the energy left behind will have varying properties due to the proximity of neighbouring gravitational effects. There is the constant pattern of suns throughout the universe, but the body make up will vary, this can be construed to the gravitational reaction effects of the energies surrounding which will as noted contract and flatten.

    In this note if the entire universe is flattening then there will be a centre somewhere as this would be gravitational mass pulling the energy down. The expansion cannot cause this otherwise the universe would not be flattening.
  10. Sep 30, 2013 #9


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    Are you referring to big bang nucleosynthesis? The expansion of the universe is not now creating hydrogen and helium. And nothing "causes" the universe to expand -- this was simply an initial condition associated with the physics of the big bang.

    Please substantiate this claim. Under what process is the expanding universe fueling the creation of radiation?
    The flatness of the universe has nothing what-so-ever to with gravitational fields. It is a result of the overall density of the universe -- a homogeneous universe at critical density has a flat geometry, and there are no gravitational fields in a homogeneous universe. Much of what you say is very speculative and not in keeping with mainstream cosmology. The forum is not for discussing personal theories.
  11. Sep 30, 2013 #10
    My error, I was not stating theory or rather personal theory as interpretation maybe described. Gravitation and energy flows are interlinked, all I am stating is that the outward boundaries are out with gravitational fields of older galaxies. These galaxies would be unable to pull on the constant energy of the outward marker energy.
    Light will bend around gravitational fields, but the amount of new light passing through older galaxies will lessen in time. Light is energy and the older galaxies are feeding off older energy, hence as the energy is depleted the central energy system will decay.
    Light is radiation, energy is radiation in one form or another. The bending of light and the collapse of stars and the flattening of the universe is ordered, only if the energy of the galaxy is fuelled at the outward regions. The energy passing back into the universe as it grows.

    The reason why we can associate it with the beginning is that the growth pattern has never changed.
    This satisfies both newton, Einstein and any constant variable permitted. The inner sections of the universe will have greater density of black holes and dead stars.

    By measuring light bending what are you looking at? Speed motion gravity movement mass, the outward boundary of the universe tomorrow is zero infinite, until the universe has passed it.

    As the growth is constantly expanding and speeding up then only by accelerating beyond the speed of light would the universe grow.

    The speed of acceleration of the universe is not being affected by gravity otherwise it would contract that is obvious and so leave only one answer. The speed is far greater than the speed of light and accelerating. As the noise of the universe is constant, this would imply the constant noise frequency of the expansion, but this would more likely to have been constant so it would most likely also come from the outer edge continually.

    If you lit a match in infinite amount of hydrogen the noise of each hydrogen atom exploding would be the same as it is the same constant, if it were 1 inch or 2,000,000 miles.

    The growth would be greater but the noise frequency would be the same. From that view point as the universe is expanding is it exploding outward infinitely. As the universe appears infinite then the answer is yes, it is possibly doing it from the speed of motion the energy created.

    The expansion is violent, how fast? How fast the growth? Can you take the measurements of speed, light, gravitational bodies then interact the known associated effects.

    Why can CERN not pass the speed of light by increasing the power?
    Photons and light are a bye product of something else. Light was not the beginning.,neither was god!
  12. Sep 30, 2013 #11


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    Stephen, you really should read some basic cosmology. You completely misunderstand modern cosmology theory. There IS no "outer" region of the universe, it is homogeneous at large scales. Are you under the impression that the "big bang" started at a single point? It sounds as though you are. This misconception is at the heart of a lot of errors in understanding cosmology.
  13. Sep 30, 2013 #12


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    To bounce off of what Phinds said, it isn't just cosmology you should look at. Your entire post is just sciencey words strung together without any real understanding of what they mean or how the concepts work and should fit together. Practically every aspect of your post is wrong at the most basic levels and I can't even begin to correct the specifics because it appears you would not correctly understand what I was saying. You need to understand what energy, radiation, light, and matter actually are and how they work and interact with each other. Along with much more.
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