A New Test Confirms Dark Energy and the Expansion of the Universe

The workings of the Universe.
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fred8615
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A New Test Confirms Dark Energy and the Expansion of the Universe

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In the standard model of cosmology, dark energy fills the universe. It causes the universe to expand at an ever-increasing rate, and it makes up more than 70% of the cosmos. But there’s a problem. When we measure the rate of cosmic expansion in different ways, we get results that disagree with each other.

There are several ways to measure cosmic expansion. One is to measure the relative motion of distant galaxies. This is done by looking at the light from supernovae within these galaxies. Type Ia supernovae have a fairly uniform standard brightness, so by measuring their observed brightness we know the distance of their home galaxy. This can be compared with the observed redshift of the galaxy to determine the Hubble parameter. It is this method that first discovered cosmic expansion was accelerating.

Another method is to look at the cosmic microwave background. While this faint afterglow of the big bang has an almost uniform temperature of about 3 K, there are small variations in temperature across different regions of the sky. The scale of these fluctuations depends upon the rate of cosmic expansion. Careful observations from the Planck spacecraft have given us a good measure of the Hubble constant. And this is completely independent of the supernova measure. In principle, these two results should agree, but they don’t.

Read more: https://www.universetoday.com/146380/a- ... -universe/
Frederick J. Barnett
"Someone's got to take the responsibility if the job's going to get done!! Do you think that's easy?!" Gregory Peck - The Guns Of Navarone

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