Calculating the age of the universe is not as simple as it seems. 100 years ago it wasn’t even a question, nobody thought that the universe could have an age. For example, in 1915 the physicist Albert Einstein was sure that the universe had always been there, and therefore had no beginning. But he did.
The latest estimate on the age of the universe comes from a 2020 Atacama Cosmology Telescope (ACT) study in an international collaboration of scientists from 41 institutions in seven different countries.
the oldest light
The ACT team calculated the age of the universe by measuring its oldest light detectable by their tools. Other scientific groups took measurements of galaxies to make estimates of the age of the universe. Everything indicates that it is 13.8 billion years old . These measurements agree with those made with Planck’s satellites in 2019 and the standard model of the universe (Lambda-CDM model).
Image of the oldest light in the universe (ACT).
We have hundreds of billions of stars in the Milky Way galaxy alone. When looking at a population of stars, you can tell how old it is by looking at what kinds of stars are still around and what kinds of stars have already disappeared completely.
“We restored the “baby photo” of the universe to its original condition, removing the wear of time and space that distorted the image. Just by seeing this sharpest baby photo or image in the universe, we can better understand how our universe came to be,” explained Professor Neelima Sehgal, from the Department of Physics and Astronomy at Stony Brook University.
This technique is the analysis of the cosmic microwave background (CMB), the residual light of the Big Bang , which helps. scientists better understand the origins of the universe, how we got to where we are on Earth, the galaxies, where we are going, how the universe may end, and when the end may occur.
“We found an expansion rate that is within the estimate of the Planck satellite team. This gives us more confidence in measurements of the oldest light in the universe,” Neelima Sehgal continued. ACT measurements suggest a Hubble constant of 67.6 kilometers per second per megaparsec. When you calculate what that means for the age of the Universe, you get about 13.8 billion years, plus a figure completely consistent with everything we know about stars.
Previous measurements
Georges Lemaître , a Belgian-born Catholic priest and physicist, put forward his theory of the expansion of the universe, widely incorrectly attributed to Edwin Hubble, though e.g. Einstein rejected it in 1927. Lemaître also proposed what became known as the of the Big Bang of the origin of the universe, which he called the hypothesis of the primordial atom or the cosmic egg.
big Bang
Precisely Edwin Hubble was the next to take a step in this direction with the discovery that there were galaxies outside the Milky Way. According to their estimates, the universe was 2 billion years old. From then on, this base was used, believing during the 1930s that it was about 3,000 million years old.
The discovery that the expansion of the Universe has accelerated surprised everyone and earned the 2011 Nobel Prize for the scientists who detected it. The demonstration that the rate of expansion is higher today means that it was slower in the past, which in turn implies that the Universe is older than previously thought. Physicists did not know then how to explain the acceleration, but they did arrive at an estimated age: 14,000 million years.
In the early 2000s, and since then, the best data we have come from the background of the cosmic microwave background (CMB): first from WMAP, then from Planck, and, since July 14, 2020, also from the Telescope of Atacama Cosmology.