New corroboration of the disconcerting observation that the universe is expanding faster than expected has scientists pondering the cause — perhaps some unknown factor involving the mysterious cosmic components dark energy and dark matter.
Two years of data from NASA’s James Webb Space Telescope have now validated the Hubble Space Telescope’s previous finding that the expansion rate of the universe is faster — by about 8 percent — than expected based on what astrophysicists know. about the initial conditions of the cosmos and its evolution over billions of years. The discrepancy is called the Hubble Voltage.
Observations from Webb, the highest-capacity space telescope ever deployed, appear to rule out the notion that data from its precursor, Hubble, was somehow flawed due to instrument errors.
“This is the largest sample of data from the Webb Telescope — its first two years in space — and confirms the intriguing Hubble Space Telescope discovery that we have been wrestling with for a decade: the universe is expanding faster than our best theories can explain,” said astrophysicist Adam Riess, from Johns Hopkins University in Maryland, main author of the study published on Monday (9) in Astrophysical Journal.
“Yes, it seems like there is something missing in our understanding of the universe,” added Riess, winner of the 2011 Nobel Prize in Physics for co-discovering the accelerated expansion of the universe.
“Our understanding of the universe contains a lot of ignorance about two elements — dark matter and dark energy — and these elements make up 96% of the universe, so this is no small feat.”
“The Webb results can be interpreted to suggest that we may need to revise our model of the universe, although it is very difficult to identify what that is at the moment,” said Siyang Li, a doctoral candidate in astronomy and astrophysics at Johns Hopkins and co-author of the study.
Dark matter, believed to comprise about 27 percent of the universe, is a hypothetical form of invisible matter whose existence is inferred based on its gravitational effects on ordinary matter — stars, planets, moons, everything on Earth. —, which represents about 5% of the universe.
Dark energy, which comprises approximately 69% of the universe, is believed to be a hypothetical form of energy that permeates vast swaths of space that counteracts gravity and drives the accelerated expansion of the universe.
What could explain the anomalous expansion rate?
“There are many hypotheses involving dark matter, dark energy, dark radiation — for example, neutrinos (a type of ghostly subatomic particle) — or gravity itself with some exotic properties as possible explanations,” said Riess.
The researchers employed three different methods to develop a specific revealing metric: distances from Earth to galaxies where a type of pulsating star called Cepheid has been documented. The Webb and Hubble measurements were in harmony.
The expansion rate of the universe, called the Hubble constant, is measured in kilometers per second per megaparsec, a distance equivalent to 3.26 million light years. A light year is the distance that light travels in one year, that is, 9.5 trillion kilometers.
According to the Standard Model of cosmology — basically, the conventional wisdom about the universe — the value of the Hubble constant should be approximately 67-68. The Hubble and Webb data give an average value of about 73, with a range of 70 to 76.
The Big Bang event, 13 or 14 billion years ago, started the universe and it has been expanding ever since. In 1998, scientists revealed that this expansion was actually accelerating, with dark energy as the hypothesized reason.
This content was originally published in Universe is expanding faster than expected; understand on the CNN Brasil website.
Source: CNN Brasil
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