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  1. Is the universe an open system?

  2. Is the expansion of the universe accelerating?

Reference links:

  1. No, the Universe is not expanding at an accelerated rate, say physicists;

  2. Cosmos Controversy: The Universe Is Expanding, but How Fast?


marked as duplicate by DilithiumMatrix, Jon Custer, sammy gerbil, David Hammen, Kyle Kanos Feb 22 '17 at 11:05

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  • 1
    $\begingroup$ 1. By definition, no. "Universe" means all existing matter and space. 2. The title of your link says No. Do you think otherwise? Why? $\endgroup$ – sammy gerbil Nov 15 '16 at 0:26
  • $\begingroup$ @sammy gerbil, you may be right. I do not know the truth. The group behind the linked story above claims ( on question #2) to have evidence which disputes a Nobel prize winning team who says otherwise. This is very interesting... On question #1, I am more convinced the universe is open system which may evolve eternally. $\endgroup$ – Dave Nov 15 '16 at 1:17
  • 4
    $\begingroup$ Possible duplicate of According to Hubble's Law, how can the expansion of the Universe be accelerating? $\endgroup$ – DilithiumMatrix Feb 21 '17 at 18:07
  • $\begingroup$ So far, my questions have no definitive and clear answers. $\endgroup$ – Dave Feb 22 '17 at 14:22

This is a classic case of media running with a story for sensationalistic purposes. I don't know how much the authors are playing along with them, but what the new article really shows is that if all you had to go on was type Ia supernovae, then an accelerating model is only better by 3 sigma than a non-accelerating model. But this leaves out all the other data that must be consistent with the supernova data-- you are not really free to treat that dataset as if it was all you have to go on. When you fold in other independent constraints, the confidence in the acceleration goes up past the 3 sigma limit. Also, as explained in https://arxiv.org/abs/1611.00999 , even if we stick to just the supernova data, a different way of plotting it shows much clearer confidence in the acceleration.

  • $\begingroup$ So far, my questions have no definitive and clear answers. $\endgroup$ – Dave Feb 22 '17 at 20:24

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