October 27, 2016

NOT JUST THE CENTER OF THE UNIVERSE, FLAT TOO:

The universe is flat as a pancake. Coincidence? : Dark energy is smoothing the expanding cosmic curves - but only exactly the right amount can make that happen (Stuart Clark, 10/27/16, New Scientist)

According to Einstein's general theory of relativity, matter and energy bend space and time, and the amount of stuff the universe contains will determine its ultimate fate. If the universe is dense enough to curve space-time in on itself, all that gravity will eventually collapse it back down to nothing. If the universe's density is low, it curves outwards - and the weakness of the gravitational pull will mean it expands forever.

But our universe seems to fit in neither camp. The most powerful test of its geometry is the variation in the cosmic microwave background, the radiation emitted shortly after the big bang. According to measurements of this radiation, the density of matter and energy is such that the universe does not curve either way: it is perfectly flat. After an eternity, its expansion should grind to a halt with no subsequent collapse.

Posted by at October 27, 2016 6:12 PM

  

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