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Paris (AFP) – The astrophysicist who led the research said Wednesday that the most accurate measurements ever taken of the universe’s formation and how fast it was expanding suggested “there is something fishy” in our understanding of the universe.
The comprehensive new study, published in The Astrophysical Journal, confirms that there is a huge discrepancy between two different ways of estimating the speed at which the universe is expanding.
About five percent of the universe is made up of what we might think of as natural matter, the study said, while the rest is dark matter and dark energy — both of which are still shrouded in mystery.
Dark energy, a hypothetical force that causes the universe to expand at an ever-increasing rate, makes up 66.2% of the universe, according to the study published in The Astrophysical Journal.
The remaining 33.8 percent is a mixture of matter and dark matter, which is also unknown but may consist of some as yet undiscovered subatomic particles.
To get to the most accurate frontier yet on what our universe is made of, an international team of researchers has observed exploding stars called supernovae.
They analyzed light from 1,550 different supernovae, ranging from close to home to more than 10 billion light a year away, when the universe was a quarter of its current age.
“We can compare it and see how the universe behaves and evolves over time,” said Dillon Prout of the Harvard-Smithsonian Center for Astrophysics and lead author of the study called Pantheon+.
two decades of analysis
The study updated data from the Pantheon project two years ago, eliminating potential problems and clarifying more accurate calculations.
“This latest analysis of Pantheon+ is the culmination of more than two decades of tireless efforts by observers and theorists around the world in deciphering the essence of the universe,” American astrophysicist Adam Rees, the 2011 Nobel Prize winner in Physics, said in a statement.
By observing supernovae in the late 1990s, Reiss and other scientists discovered that the universe was not only expanding, but also doing so at an increasing rate, meaning galaxies were moving away from each other.
“It was as if I threw a ball, and instead of the ball dropping, it jumped and kept accelerating,” Pruitt said of the surprise of this discovery.
Pantheon+ has also collected data through the SH0ES supernova collaboration to find what is believed to be the most accurate measurement of how fast the universe is expanding.
They estimated that the universe is currently expanding at 73.4 kilometers per second every megaparsec, or 3.26 million light-years. According to a Harvard-Smithsonian statement, this amounts to about 255,000 kilometers (160,000 miles) per hour.
but there is a problem.
– Hubble tension –
Measurement of the cosmic microwave background radiation, which can look much further back in time to roughly 300,000 years after the Big Bang, indicates that the universe is expanding at a much slower rate — about 67 kilometers per megaparsec.
This discrepancy has been called the Hubble tension after the American astronomer Edwin Hubble.
Prott said the Pantheon+ results raised the degree of certainty about the Hubble tension above what’s known as the five sigma threshold, meaning the discrepancy “can no longer be attributed to luck.”
“It certainly points to the possibility that there is something fishy in our understanding of the universe,” Pruitt told AFP.
Some of the possible, unverified theories about the paradox might include another type of dark energy in the very early universe, primordial magnetic fields, or even that the Milky Way lies in a cosmic vacuum, which could slow it down.
But for now, Pruitt said, “We as scientists thrive on not understanding everything.
“There is still a potentially great revolution in our understanding, potentially coming into our lives,” he added.
© 2022 AFP