“Eventually, we reach the utmost limits of our telescopes.There we measure shadows and search among ghostly errors of measurement for landmarks that are scarcely more substantial,” wrote Edwin Hubble in 1916, inventor of the famous “constant” that describes how fast the universe is expanding at different distances from a particular point in space, implying the existence of a timescale or age for the universe. New research by a team of astronomers employing a novel approach using known distances of 50 galaxies from Earth have estimated the age of the universe at 12.6 billion years.
Hubble’s measurements of today’s expansion rate do not match the rate that was expected based on how the Universe appeared shortly after the Big Bang over 13 billion years ago. In 2019, using new data from the NASA/ESA Hubble Space Telescope, astronomers have significantly lowered the possibility that this discrepancy is a fluke.
“The Hubble tension between the early and late Universe may be the most exciting development in cosmology in decades,” said lead researcher and Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University. “This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This disparity could not plausibly occur by chance.”
Approaches to date the Big Bang and the birth of the universe, rely on mathematics and computational modeling, using distance estimates of the oldest stars, the behavior of galaxies and the rate of the universe’s expansion. The idea is to compute how long it would take all objects to return to the beginning.
A recent technique to measure the age of the universe uses observations of leftover radiation from the Big Bang, reports the University of Oregon — “It maps bumps and wiggles in spacetime – the cosmic microwave background, or CMB – and reflects conditions in the early universe as set by Hubble’s constant.”
A New Approach
A new approach reports James Schombert, a professor of physics at the University of Oregon. In a paper published July 17 in the Astronomical Journal, he and colleagues, recalibrates a distance-measuring tool known as the baryonic Tully-Fisher relation independently of Hubble’s constant that solves the “distance-scale problem” as it is known, resolving the “vast distances to galaxies and the signposts that are faint and hard to calibrate.”
Schombert’s team recalculated the Tully-Fisher approach, using accurately defined distances in a linear computation of the 50 galaxies as guides for measuring the distances of 95 other galaxies. The universe, he noted, is ruled by a series of mathematical patterns expressed in equations. The new approach more accurately accounts for the mass and rotational curves of galaxies to turn those equations into numbers like age and expansion rate.
Schombert’s team’s approach determines the Hubble’s constant – the universe’s expansion rate – at 75.1 kilometers per second per megaparsec, give or take 2.3. A megaparsec, a common unit of space-related measurements, is equal to one million parsecs. A parsec is about 3.3 light years. All Hubble’s constant values lower than 70, his team wrote, can be ruled out with 95 percent degree of confidence.
Traditionally used measuring techniques over the past 50 years, Schombert said, have set the value at 75, but CMB computes a rate of 67. The CMB technique, while using different assumptions and computer simulations, should still arrive at the same estimate, he said.
Physics of the Universe Incomplete
“The tension in the field occurs from the fact that it does not,” Schombert said mirroring Adam Reiss’ comments above.. “This difference is well outside the observational errors and produced a great deal of friction in the cosmological community.”
Calculations drawn from observations of NASA’s Wilkinson Microwave Anisotropy Probe in 2013 put the age of the universe at 13.77 billion years, which, for the moment, represents the standard model of Big Bang cosmology. The differing Hubble’s constant values from the various techniques generally estimate the universe’s age at between 12 billion and 14.5 billion years.
The new study, based in part on observations made with the Spitzer Space Telescope, adds a new element to how calculations to reach Hubble’s constant can be set, by introducing a purely empirical method, using direct observations, to determine the distance to galaxies.
“Our resulting value is on the high side of the different schools of cosmology, signaling that our understanding of the physics of the universe is incomplete with the hope of new physics in the future,” he said.
The image at the top of the page took researchers at the Instituto de Astrofísica de Canarias almost three years to produce. It’s the deepest image of the universe ever taken from space, recovering a large quantity of ‘lost’ light around the largest galaxies in the iconic Hubble Ultra-Deep Field.
The Daily Galaxy, Max Goldberg, via University of Oregon