Far out cosmology: age of universe revisited (Introduction)

by David Turell @, Saturday, November 26, 2022, 18:46 (64 days ago) @ David Turell

A thorough explanation of the estimated age:

https://bigthink.com/starts-with-a-bang/universe-13-8-billion-years-302173/?utm_source=...

"We now state, with confidence, that the Universe is 13.8 billion years old. But how confident can we really be in that answer?

***

"The simplest and most straightforward way to measure the age of the Universe is simply to look at the objects that are in it: stars, for instance. We have hundreds of billions of stars in the Milky Way galaxy alone, and the overwhelming majority of the ancient history of astronomy was devoted to studying and characterizing stars. It remains an active field of research today, as astronomers have uncovered the relationship between observed properties of stellar populations and how old they are.

***

"...when we look at a population of stars, we can tell how old it is by looking at what types stars still remain, and what classes of stars are completely gone.

***

"Today, we can reliably conclude there’s a lower limit to the age of the Universe of around 12.5-to-13 billion years from the stars we measure, but that doesn’t pin down the age precisely. It’s a good constraint to have, but to arrive at an actual figure, we’d like a better method.

***

"Observations ranging from the abundances of the light elements to the clustering of galaxies to how galaxy clusters collide to distant supernovae to the fluctuations in the cosmic microwave background all point toward the same Universe. In particular, it’s made up of:

"68% dark energy,
27% dark matter,
4.9% normal matter (protons, neutrons, and electrons),
0.1% neutrinos,
0.01% photons (particles of light, or radiation),
and less than 0.4% of everything else, including spatial curvature, cosmic strings, domain walls, and other fanciful, exotic components.

***

"Beginning the early 2000s, and ever since, the best data we have comes from the Cosmic Microwave Background: first from WMAP, then from Planck, and, as of July 14, 2020, from the Atacama Cosmology Telescope as well.

"Those values have all converged on the same expansion rate: 68 km/s/Mpc, with an uncertainty of just 1–2%. When you calculate what that means for the age of the Universe, you get a very robust 13.8 billion years, completely consistent with everything we know about stars.

***

"What’s fascinating about this, however, is that the derived age barely changes at all; if you explore the full range of what is and isn’t allowed, that 13.8 billion year old figure only comes along with an uncertainty of about 1%: between 13.67 and 13.95 billion years.

***

"...the data we have is all consistent with one particular age of the Universe: 13.8 billion years, with an uncertainty of only 1% on that value. It cannot be a billion years older or younger than this figure, not unless a whole host of things that we’ve measured have driven us to wildly incorrect conclusions. Unless the cosmos is lying to us, or we’re unwittingly fooling ourselves, what we know of as the hot Big Bang occurred between 13.67 and 13.95 billion years ago: no less and no more. Don’t believe any claims to the contrary without comparing them to the full suite of data!"

Comment: very thorough article. I've had to skip over man examples of measurements. Does not answer the question of the cause of the origin of the universe. And the universe evolved until now. It in one of the several evolutions God managed/created


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