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New Observations Agree That the Universe is 13.77 Billion Years old

The oldest light in the universe is that of the cosmic microwave background (CMB). This light was formed when the dense matter at the beginning of the universe finally cooled enough to become transparent.
It has traveled for billions of years to reach us, stretched from a bright orange glow to cool, invisible microwaves.
Naturally, it is an excellent source for understanding the history and expansion of the cosmos.

The CMB is one of the ways we can measure the rate of cosmic expansion.
In the early universe, there were small fluctuations of density and temperature within the hot dense sea of the big bang. As the universe expanded, the fluctuations expanded as well.
So the scale of fluctuations we see in the cosmic microwave background today tells us how must the universe has grown.
On average, the fluctuations are about a billion light-years across, and this gives us a value for the rate (the Hubble parameter) as somewhere between 67.2 and 68.1 km/sec/Mpc.

The Atacama Cosmology Telescope. Credit: Jon Ward

Of course, the CMB isn’t the only way you can measure the Hubble parameter.
In an earlier post, I talked about how you can use variable stars and distant supernovae to create a cosmic distance ladder that tells you the rate of expansion. The problem is, this alternative method gives a larger value for the Hubble parameter.
If the supernova method is right, then the universe is younger and has expanded more quickly than the CMB scale seems to support.
For a while, the hope has been that new observations and new methods of measuring cosmic expansion would solve this problem, but a new study dashes those hopes.
This study looked at the cosmic microwave background using the Atacama Cosmology Telescope (ACT) in Northern Chile.

How the CMB arises from last scattering. Credit: Yacine Ali-Haïmoud

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https://www.universetoday.com/149530/new-observations-agree-that-the-universe-is-13-77-billion-years-old/

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