Observations

Signals from the beginning of the Universe

Dark Sector Lab

The BICEP2 telescope on the left and the South Pole Telescope in the Dark Sector Lab, located just over one kilometre from the Geographic South Pole. Courtesy Steffen Richter, Harvard University

Have you flexed your biceps today? Early this morning (18 March 2014) at the Harvard-
Smithsonian Center for Astrophysics astronomers involved with the BICEP2 project made what maybe well turn out to be a historic announcement. They announced the detection of a polarisation pattern in a region of the sky indicating gravitational waves in the first few instants after the Big Bang.

There are numerous other teams of astronomers searching for these patterns in the Cosmic Microwave Background Radiation (CMB) including the European Planck spacecraft. Today’s results can only be fully accepted if they are subsequently verified by one or more of these other teams. When the results are verified a Nobel Prize will be clearly in the offing.

The twisting pattern in the polarisation of the CMB detected by the BICEP2 telescope

The twisting pattern in the polarisation of the CMB detected by the BICEP2 telescope. The line segments show the polarisation at different spots in the sky, while the red and blue colours highlight the clockwise and anti-clockwise twisting of this “B-Mode” pattern. Courtesy of the BICEP2 project

Anyone who wears or has looked through a pair of Polaroid sunglasses is familiar with the polarisation of light. Light when it consists of vibrations in only one direction perpendicular to the direction of travel is said to be polarised. Polarisation has already been detected in the CMB, but the BICEP2 astronomers have found a particular twisting pattern of polarisation called B-Mode. This claimed discovery is causing great excitement for that mode of polarisation is the imprint of gravitational radiation from the very first instants of the Big Bang.

Illustration showing the growth in the scale of the Universe with time and indicating some of the major events in its history. Courtesy of the BICEP2 project

Illustration showing the growth in the scale of the Universe with time and indicating some of the major events in its history. Courtesy of the BICEP2 project

The Universe began in the Big Bang as a tiny quantum fluctuation. According to theory within a tiny fraction of a second Inflation took over and the Universe grew to a macroscopic size. We can only look back to the era at 380 000 years after the Big Bang when the Universe had cooled sufficiently to allow the free passage of photons of light. Arno Penzias and Robert Wilson discovered this CMB just on 50 years ago.

In recent times satellites like COBE, WMAP and Planck have made increasingly sharp maps showing tiny temperature fluctuations in the CMB. These indicate density fluctuations that eventually grew into galaxies, stars and planets.

BICEP2 has now found the B-Mode polarisation patterns that are believed to be the imprint of gravitational waves originating in the short period of Inflation that followed the Big Bang. A new window has opened into the study of the origins of the Universe and the high energy physics that occurred at that time. It examines the Grand Unified Theories that link three of the main forces in Nature and suggests that the fourth force, gravity, can be quantised as theoreticians have predicted.

Further reading:

BICEP2 2014 Release Frequently Asked Questions
First Direct Evidence of Big Bang Inflation

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