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Bicep2 will allow us to work out how hot the big bang was

Sunday, 23. March 2014 - 12:52

It seemed that no sooner had everyone calmed down after the confirmation of the Higgs boson than another huge scientific discovery was announced. News of Bicep2 broke when the Guardian published an online article last Friday, and since then cosmologists and physicists have taken to the internet to try to explain, with varying degrees of success, what the fuss is about. My turn.

Bicep2, which stands for Background Imaging of Cosmic Extragalactic Polarisation, is the second phase of an experiment being done at the South Pole, where the air is clear and dry, aimed at detecting weak microwave radiation from space using highly sensitive telescopes. Their work began with the cosmic microwave background, or CMB, a form of electromagnetic radiation that pervades space.

Bicep2 is a telescope whose name is short for Background Imaging of Cosmic Extragalactic Polarisation.
Photograph: Steffen Richter/AP

It was first detected half a century ago and is a cornerstone of cosmology, supporting evidence for a cataclysmic event known as the hot big bang that happened 14bn years ago. CMB is the afterglow of that event and has been washing through the universe since. In recent years, tiny temperature differences in the CMB have confirmed that the universe is a little bit lumpy, with the matter in some regions of the early universe denser than in others, which allowed galaxies and stars to be formed.

But after the press conference on Monday at the Harvard-Smithsonian Centre for Astrophysics, the Bicep2 result also tells us something more profound. It tells us that CMB is slightly polarised in some directions, and therefore carries within it the imprint of the ripples in space-time predicted by Einstein almost a century ago: what is known as primordial gravitational waves. These are the tremors of creation itself, arriving indirectly in the Bicep2 telescopes.

Of even more interest to cosmologists is what the results tell us about an idea that has been around since the 1980s, known as inflation. The theory goes that a tiny fraction of a second after the universe came into being it underwent a period of expansion, driven by a mysterious dark energy, which then initiated the hot big bang and provided all the stuff of the universe, including the stars, the planets and us.

The Bicep2 results provide strong support for inflation theory and will allow us to work out how much of that dark energy was driving the inflation of the universe, hence how rapidly it happened – as well as just how hot the big bang was.

Jim Al-Khalili

Source: 
www.theguardian.com
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Bicep2
big bang
inflation of the universe