Galaxy’s location in a vast cosmic void could help explain dueling universe expansion rates
Millennium Simulation Project
If the Milky Way exists in the biggest cosmic void ever observed, that could solve a puzzling mismatch between ways to measure how fast the universe is expanding.
Observations of 120,000 galaxies bolstering the Milky Way’s loner status were presented by Benjamin Hoscheit June 7 at a meeting of the American Astronomical Society in Austin, Texas. Building on earlier work by his adviser, University of Wisconsin‒Madison astronomer Amy Barger, Hoscheit and Barger measured how the density of galaxies changed with distance from the Milky Way.
In agreement with the earlier study, the pair found that the Milky Way has far fewer neighbors than it should. There was a rise in density about 1 billion light-years out, suggesting the Milky Way resides in an abyss about 2 billion light-years wide.
Simulations of how cosmic structures form suggest that most galaxies clump along dense filaments of dark matter, which are separated by vast cosmic voids.
If the Milky Way