The Scale of the Universe
Virginia Trimble discusses Einstein's contribution to past understanding of the scale of the universe.
Gustav Tammann explains how Malmquist Bias causes some to overestimate the value of Hubble's constant.
Sidney van den Bergh relates how measurements with Cepheid variable stars might indicate that others have underestimated Hubble's constant.
Moderator John Bahcall (left) discusses issues with Sidney van den Bergh. Bahcall wonders if at least part of the present disagreement might stem from bias in choosing the list of local galaxies from which Hubble's constant is computed.
Photographs courtesy of Peter Leonard.