How fast is the universe expanding? The mystery endures

WASHINGTON: Scientists have known for decades that the universe is expanding, but research in the past few years has shaken up calculations on the speed of growth -- raising tricky questions about theories of the cosmos.

The rate of expansion -- known as the "Hubble constant" -- is a central part of the quest to discover the origins of the universe, with astrophysicists believing they are getting closer and closer to the exact speed.

In 1998, two teams of researchers found that the rate of expansion accelerated with distance, and that the universe was filled with mysterious "dark energy" that has caused the acceleration for 14 billion years -- earning them a 2011 Nobel prize.

The unit of measurement for the Hubble constant is kilometers per second per megaparsec -- which is three million light-years. According to two different methods, the rate of expansion is either 67.4 -- or 73.

Now a study, written by researchers at the Max Planck Institute of Astrophysics in Germany and other universities, has described a new method of gauging the universe´s accelerating growth.