Swiss-cheese model of the cosmos full of holes

摘要

A Universe riddled with holes would do away with the need for dark energy. Unfortunately that idea itself now seems to have a few holes. In 1998, astronomers found that distant supernovae were dimmer, and thus farther away, than expected. According to the standard model of cosmology, which assumes that the universe is homogenous on large scales, this suggested that the expansion of the universe was speeding up. That acceleration was attributed to a mysterious "dark energy" inherent in the fabric of space-time. Then, last year, Edward Kolb of the Fermi National Accelerator Laboratory in Batavia, Illinois, and colleagues re-examined the supernovae data in the context of the "Swiss-cheese" model, which assumes the universe is full of holes or voids with less matter than other regions. It was inspired by the accidental discovery of a giant void about 1 billion light years across. The astronomers who discovered the supernovae anomaly in the late 1990s had assumed that matter was distributed more or less evenly. But in the Swiss-cheese model, less dense regions would act as a concave lens, bending part of the light from a distant object away from us. Therefore supernova light that travelled through a series of such voids would appear dimmer than expected without the need to invoke dark energy.