Timeline for How big is the universe. How does it works?
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7 events
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| May 9, 2014 at 20:20 | comment | added | Stan Liou | No, because any stress-energy term that's proportional to the metric tensor is going to be a perfect fluid with pressure equal to the negative of its energy density, which is not the case for the non-Λ matter in our universe. Pressure and energy density intermix between local inertial frames, and this special equality allows it to be invariant. ... The logic about extrapolating works with regard to spatial curvature only, which is the only kind you've explicitly considered in the answer. Although I'd note that the links you gave assume a more general subclass of FLRW than dS/M/AdS trio anyway. | |
| May 9, 2014 at 12:18 | comment | added | Gerald | @StanLiou If we take the large-scale mass-energy of the observable universe as equally distributed, couldn't the resulting stress-energy tensor be re-interpreted as part of the metric, like Lambda can be re-interpreted as vacuum energy? The question has been about CMB features, and their appearent magnification/reduction by the large-scale curvature of spacetime. I've no better idea, how to keep the answer simple enough to answer the question essentially. Otherwise we've to deal with arbitrarily curved manifolds which are almost flat in the large-scale observable universe, due to mass-energy. | |
| May 9, 2014 at 5:29 | comment | added | Stan Liou | It would be equally true to say that if the universe negatively curved, it could be a fragment of Minkowski spacetime; 'could be' has quite a bit of wiggle room. But the FLRW family of solutions is so much more populous than the special cases of dS/Minkowski/AdS spacetimes that I think it it is somewhat misleading to single them out, except perhaps to say that they're all maximally symmetric. Being lambdavacua, all three are observationally ruled out, since our universe contains non-negligible stress-energy besides the cosmological constant, and so they cannot be "possible extrapolations." | |
| Apr 7, 2014 at 21:48 | history | edited | Gerald | CC BY-SA 3.0 |
Added possible implication of the curvature of the observable universe for the "whole" universe
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| Apr 7, 2014 at 20:23 | history | edited | Gerald | CC BY-SA 3.0 |
improved some formulations, added link to LCDM
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| Apr 7, 2014 at 12:59 | history | edited | Gerald | CC BY-SA 3.0 |
minor correction
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| Apr 7, 2014 at 12:33 | history | answered | Gerald | CC BY-SA 3.0 |