Ever since the astronomer Edwin Hubble demonstrated that the further apart two galaxies are, the faster they move away from each other, researchers have measured the expansion rate of the universe (the Hubble constant) and the history of this expansion. Recently, a new puzzle has emerged, as there seems to be a discrepancy between measurements of this expansion using radiation in the early universe and using nearby objects. Researchers from the Cosmic Dawn Center, at the Niels Bohr Institute, University of Copenhagen, have now contributed to this debate by focusing on velocity measurements. The result has been published in Astrophysical Journal.