Measuring Distances to More Supernovae Sharpens the Hubble Constant Debate

A recent Astrophysical Journal letter by veteran astronomer Allan Sandage (Carnegie Observatories, Pasadena, California) and coworkers offers some solace to troubled adherents of the cosmological scenario most favored by the theorists. The contentious observational issue is the value of $H0,$ the Hubble constant. A variety of measurement schemes that use properties of galaxies have in recent years put $H0$ between 80 and 85 km/s per megaparsec. (A megaparsec is 3.3 million light‐years or $3.1×1019 km.$⁠) But Sandage and company, using supernovae, have long held out for a value closer to 50 km/(sMpc). “Our new paper,” Sandage contends, “is the beginning of the end of the Hubble‐constant wars.”