At the top of the Atacama Desert in Chile, miles from the glowing glow of light pollution, the isolated Atacama Cosmology Telescope is in a prime position to look for answers in the sky. The question that comes to mind most recently? The age of the universe, a cosmic dilemma that can be answered in different ways, depending on how the accelerated expansion of the universe is measured.
A document recently published in the Journal of Cosmology and Astroparticle Physics has measured the speed of this expansion, called the Hubble constant, using the National Science Foundation’s telescope in Chile.
The team found that the Hubble constant was 42 miles per second per megaparsec; that is, for every megaparsec, or 3.26 million light-years, the speed of the universe’s expansion increases by 42 miles per second. The number found by the international team of astronomers and physicists, after 730 days of observation spanning from 2013 to 2016, was almost the same as the European Space Agency’s Planck satellite in 2013.
“Now we have given an answer where Planck and [Atacama Cosmology Telescope] okay, “said Simone Aiola, a researcher at the Center for Computational Astrophysics at the Flatiron Institute and co-author of the paper. in a press release. “He talks about the fact that these difficult measures are reliable.”
There is a rather important reason why it was worth recalculating the constant: there are some ways to measure the rate of expansion of the universe, from which the age of the universe can be deduced. You can measure speed based on stellar things near us, like Cepheid stars. You can also measure expansion by looking at the polarized light from the cosmic microwave background of the universe, the farthest detectable radiation from the Big Bang, which is what the Atacama team did here. This diffuse light has variations in its polarization, allowing scientists to measure how far light has traveled and how long that journey has taken. This is why it is important to understand the rate of expansion of the universe: it changes how far light has come and therefore the age of everything.
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Here’s the problem: These two ways of calculating the Hubble constant have given very different rates:a 2019 study reached nearly 46 miles per second per megaparsec, while another of the same year a number has been found that divides the difference between the other two. While the differences may seem small, different estimates mean a range of hundreds of millions of years to determine how old our universe is. (The higher the constant, the younger the universe).
The findings of the Atacama team place the age of the universe at around 13,777 million years. In comparison, our solar system is about 4.57 million years old and homo sapiens emerged about 300,000 years ago.
The different figures so far do not mean that any party is necessarily wrong (although the team behind the new document, working with better-resolution images of the cosmic microwave background than its predecessors in Planck, claimed that mathematics of the previous equipment were solid). What it definitely means is that we are missing something in terms of how the expansion of the universe works.
The disparity between local and distant measures of the Hubble constant could mean that “there is a problem with one of the types of measures that we are not interpreting correctly and therefore there is some kind of systematic problem with one measure or the other. “, he said. Michael Niemack, an astrophysicist at Cornell University and co-author of the recent article. “The most exciting possibility is that something is missing from our cosmological model.”
It is possible that the best is yet to come to the Atacama telescope, which had its first light in 2007 and has the advantage of being on the ground, making it easier to manage than a space-based telescope.
“We have yet to extract all the information from the data we already collected with the Atacama cosmology telescope,” Steve Choi, an astrophysicist at Cornell University and lead author of the paper, said in an email. “I hope we learn even more exciting physics about our universe with upcoming experiments at Atacama, such as the first CCAT and the Simons Observatory,” referring to two upcoming high-altitude observatories in the desert. The CCAT-prime telescope was renamed the Fred Young submillimeter telescope this September and will examine a number of cosmological features, while the Simons Observatory will focus its observation capabilities on the cosmic microwave background.
Perhaps one of the parts that assesses the age of the universe overlooks something in its mathematics: with the many known unknowns of space science and things that are totally unknown, it is possible. But, according to Niemack, just as easily there could be something else that explained the different numbers.
“This could be an indication that we are about to discover something new and exciting that we didn’t know before about how our universe works,” he said.