https://phys.org/news/2019-07-scientists-debate-seriousness-problems-hubble.html Scientists debate the seriousness of problems with the value of the Hubble Constant: Astronomers, astrophysicists and particle physicists gathered recently at the Kavli Institute for Theoretical Physics at the University of California to discuss the seriousness of differing measurements of the Hubble Constant. They met to talk about a problem that has become a major concern in astrophysics—figuring out how fast the universe is actually expanding. more at link...... the paper: https://science.sciencemag.org/content/365/6451/306 Summary: Last week, leading experts at clocking one of the most contested numbers in the cosmos—the Hubble constant, the rate at which the universe expands—gathered in hopes that new measurements could point the way out of a brewing storm in cosmology. No luck so far. A hotly anticipated new cosmic yardstick, reliant on red giants, has served only to muddle the debate about the actual value of the constant, and other measurements brought no resolution. The meeting, at the Kavli Institute for Theoretical Physics in Santa Barbara, California, was the latest episode in a saga stretching back to the 1920s, when Edwin Hubble established that the farther one looks into space, the faster galaxies are speeding away from Earth. Since then, scientists have devoted entire careers to refining the rate of that flow, Hubble's eponymous constant, or H0. But recently, the problem has hardened into a transdisciplinary dispute: Cosmologists, looking at the most ancient universe, calculate a lower H0 than astronomers, looking out from the neighborhood of the Milky Way. <<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>> As the title suggests, it appears to be a matter of refinement, and comparing of methodologies and selecting the most accurate. Another recent article discussing this refinement and methodologies is at...... https://phys.org/news/2019-07-hubble-constant-mystery-universe-expansion.html an extract from that article....... "In a new paper accepted for publication in The Astrophysical Journal, Freedman and her team announced a new measurement of the Hubble constant using a kind of star known as a red giant. Their new observations, made using Hubble, indicate that the expansion rate for the nearby universe is just under 70 kilometers per second per megaparsec (km/sec/Mpc). One parsec is equivalent to 3.26 light-years distance. This measurement is slightly smaller than the value of 74 km/sec/Mpc recently reported by the Hubble SH0ES (Supernovae H0 for the Equation of State) team using Cepheid variables, which are stars that pulse at regular intervals that correspond to their peak brightness. This team, led by Adam Riess of the Johns Hopkins University and Space Telescope Science Institute, Baltimore, Maryland, recently reported refining their observations to the highest precision to date for their Cepheid distance measurement technique." Still, this refinement does not only apply to the rate of universal expansion, but also to the calculations involved with measuring the distances of galaxies and stars, via parallax error, type 1a S/nova, Cepheid variables etc. Any positive thoughts?
