HOW OLD IS THE UNIVERSE?

 

HOW OLD IS THE UNIVERSE?

 The universe is looking younger every day, it seems. New calculations suggest the universe could be a couple billion years younger than scientists now estimate, and even younger than suggested by two other calculations published this year that trimmed hundreds of millions of years from the age of the cosmos.

                              

Fortunately, the launch of NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) in 2001 and the European Space Agency’s Planck satellite in 2009 changed all that. Still, astronomers’ attempts during the previous century to narrow the age estimates makes for a fascinating detective story. 

Before WMAP and Planck, the best approach for determining the universe’s age relied on the much-debated Hubble constant, a figure that describes the rate at which the universe is expanding. The generally accepted age of the universe is 13.7 billion years, based on a Hubble Constant of 70.To find the Hubble constant, astronomers observe distant galaxies and measure their distances (by using Cepheid variable stars or other objects of known intrinsic brightness) as well as how fast they recede from Earth. They then determine the Hubble constant by dividing the galaxy’s speed of recession by its distance. Once they decide on a value for the Hubble constant, they can estimate the maximum age of the universe by calculating the constant’s reciprocal. The real problem though, is that the various studies disagree so wildly with each other, to the tune of a billion years. But they’re not the only ones – the battle lines are commonly drawn by the methods used. Whenever scientists measure the CMB they arrive at figures close to 13.8 billion years old and a Hubble constant of around 67 km/s/Mpc, and studying the motions of galaxies usually yields a younger age and a Hubble constant closer to 74 km/s/Mpc. Obviously something is amiss, and more research is needed to determine where the truth lies.

Harvard astronomer Avi Loeb, who wasn't part of the study, said it an interesting and unique way to calculate the universe's expansion rate, but the large error margins limits its effectiveness until more information can be gathered."It is difficult to be certain of your conclusions if you use a ruler that you don't fully understand," Loeb said.