The runaway universe

It could be even bigger than we thought: not only is the universe expanding (as astronomers have long known) but its rate of expansion is increasing. Observations of supernovas in 1998, if accurate, show that the cosmos is spreading and dispersing. In a neat, up-to-date introduction to cosmology and astrophysics, prolific astronomy popularizer Goldsmith (The Astronomers; The Hunt for Life on Mars) explains how the universe might be ""shaped"" and why its sped-up growth is such a surprise. Einstein's theories introduced a number called the cosmological constant: if that number had a certain (below-zero) value, the universe would stay the same size. Recent models of the expanding universe set Einstein's constant at zero. Now it turns out the constant has a value above zero.