Reevaluating the cosmological constant

Nature : Theorists have struggled to reconcile the observed expansion of the universe with their theoretical expectations, writes Kate McAlpine for Nature. In particular, they worry that the cosmological constant, which appears to help account for the observed expansion, is much smaller than predicted by quantum field theories. Moreover, when the cosmological constant is expressed in time units, its value is suspiciously close to the age of the universe. Now cosmologists John Barrow and Douglas Shaw of the University of Cambridge have created a model whereby the cosmological constant depends on when and where it is measured. The researchers’ results appear in Physical Review D.