(ORDO NEWS) — A team of researchers led by astronomers Brent Tully and Ehsan Kurkchi of the University of Hawaii at Manoa has compiled the largest collection of high-precision distances to galaxies in history, dubbed Cosmicflows-4.
Using eight different methods, they measured the distances of up to 56,000 galaxies.
Galaxies like the Milky Way are the building blocks of the universe, each made up of several hundred billion stars.
Measurements of the distances to galaxies, combined with information about their receding rates from us, determine the scale of the universe and the time that has elapsed since its birth.
Based on the recently published measurements, the researchers deduced the expansion rate of the universe, called the Hubble constant, or H.
The team’s study yields a value of H = 75 (km/s)/Mpc, with a very small statistical error of about 1.5%.
There are several ways to measure distances to galaxies. The Cosmicflows program, led by Tully and Kurkchi, includes both their own original material based on the two methods and information from many previous studies.
Because Cosmicflows-4 includes distances derived from multiple independent, distinct distance estimates, intercomparisons should reduce the potential for large bias.
Astronomers have put together a chart that shows the universe is a little over 13 billion years old, but scientists are faced with one major dilemma.
The physics of the evolution of the universe, based on the standard model of cosmology, predicts H = 67.5 (km/s)/Mpc, with an uncertainty of (1 km/s)/Mpc.
The difference between the measured and predicted values of the Hubble constant is 7.5 (km/s)/Mpc, much larger than would be expected given the statistical uncertainties.
Either there is a fundamental problem with our understanding of the physics of the cosmos, or there is a hidden systematic error in measuring distances to galaxies.
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