Revolution in Cosmology Resolves Dispute over Universe's Age 

Just under seven years ago, astronomers using the Hubble space telescope presented results they hoped would help answer one of the most contentious issues in astronomy of the 20th century – the question of the distance scale of the universe. But there was some unease when the result was announced. According to the report, other galaxies were close enough that, extrapolating backwards from their current rate of recession and making adjustments for the influence of gravity, they all would have been together (that is, the Big Bang would have occurred) as recently as 8 billion years ago. Unfortunately, there was strong evidence already in place that some stars were at least 12-15 billion years old – apparently predating the origin of the universe itself! 

While these two highly irreconcilable values for the universe's age certainly posed a serious challenge to astronomers, most simply assumed that better measurements would place the distance scale back in line with the older age. What no one expected is that resolution to this problem would lie not in corrected measurements but a revolution in cosmology, and the apparent discovery of what amounts to a mysterious new essence of the cosmos – a "fifth element" that hides in vacuum and drives the expansion of the universe. 

The scientific study of the age and origin of the universe is intimately linked with the measurements of extragalactic distance, and consequently the science did not even exist until measurement techniques accurate to such scales were invented. Distance measurement has always been difficult for astronomers – until the 1800s, no one knew even the distance to the nearest star (other than the Sun)