IT IS ONE of the largest mysteries in cosmology—and getting larger on a regular basis. Ever since Edwin Hubble, an American astronomer, printed observations of distant galaxies in 1929, scientists have identified that the universe is increasing. For nearly 30 years they’ve identified that the enlargement is accelerating (that discovery, made in 1998, was honoured with a Nobel prize in 2011). What they can’t agree on, although, is how briskly it’s presently rising.
