Universe’s growth revealed over space of time

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Astronomers say they have made the best measurement yet of how fast the universe is expanding during the 13 billion years since its formation.

They have discovered that 10.8 billion years ago the universe was expanding by one per cent every 44 million years.

The team from the Sloan Digital Sky Survey (SDSS) combined two different methods of using quasars and intergalactic hydrogen gas to measure the expansion rate.

They looked at 140,000 distant quasars, luminous regions in the centre of massive galaxies, when the universe was only one-quarter of its present age.

The position of the gas clouds are mapped in three dimensions and at different distances the gas blocks showed different coloured light from the luminous quasars.

The astronomers then measured how much the universe had expanded since the light passed through each patch of hydrogen.

Dr Matthew Pieri, from the Institute of Cosmology and Gravitation at the University of Portsmouth, said: “A little over a year ago we tried this for the first time and demonstrated that it really works.

“Now we’re back with twice as much data and with remarkable precision of two per cent. We are measuring the expansion of the universe with exquisite detail. Like the rings of a tree trunk that tell is its age, each quasar spectrum becomes an archive of the universe’s history.”

He explained that In the past five billion years the universe had started to rapidly expand due to a mysterious repulsive force called dark energy.

Scientists are investigating how and why it is expanding in order to understand the nature of dark energy.

He said: “We are measuring the expansion rate better than at any point since the afterglow of the Big Bang, known as the Cosmic Microwave Background (CMB), and that precision is giving us a hint that maybe we aren’t getting what we expected and so maybe the universe isn’t quite as we had thought.

“It’s odd, but nothing you’d want to hang your hat on just yet – it’s going to be fun finding out where the truth lies.”