"Astronomers say they have found the first evidence of “gravitational waves”, ripples in the fabric of space-time, bolstering the Big Bang theory of the birth of the universe 13.8bn years ago."
Scientists can now be more confident that the Big Bang triggered expansion at an unbelievable rate, with the newborn universe growing a trillion-trillion-trillion times in an infinitesimal fraction of a second.
“Detecting this signal is one of the most important goals in cosmology today,” said John Kovac of Harvard University, the project leader. Cosmologists not directly involved in the research joined the team in acclaiming the discovery as a landmark in understanding the universe.
Everything we can see today – galaxies, stars, planets and people – originated in tiny “quantum fluctuations” in space that were amplified exponentially by cosmic inflation.
Albert Einstein predicted the existence of gravitational waves almost a century ago and modern astronomers have been looking for them for several years with increasingly powerful instruments. Now the Bicep 2 radio telescope at the US polar base in Antarctica has achieved success.
“This is the most important result in our field so far this century,” said David Wands, professor of cosmology at Portsmouth University in the UK. The last discovery of comparable significance came in 1998 when astronomers found that mysterious “dark energy” was counteracting gravity and fuelling the expansion of the universe today.
The Bicep 2 telescope was built to analyse the “cosmic microwave background”. This faint radiation, which perfuses space, is often referred to as an “afterglow of the Big Bang”. It was released when the universe was 380,000 years old and, for the first time, cool enough for light to pass through space.
Although the microwave background has been mapped with increasing accuracy by satellite observatories – most recently by Europe’s Planck telescope last year – these maps have so far just shown variations in the temperature or frequency of the radiation.
Bicep 2 found subtle variations in the polarisation or orientation of the electromagnetic waves. Gravitational waves spawned by cosmic inflation would have squeezed space as they travelled through it, producing a characteristic polarisation pattern in the radiation.
“The swirly B-mode pattern [that we detected] is a unique signature of gravitational waves,” said Chao-Lin Kuo of Stanford University, another team scientist.
The South Pole is an ideal place to look for such signals because the atmosphere there is so cold, dry and stable.
The team says the polarisation is stronger than many cosmologists expected. Three years of data analysis ruled out other possible causes of the pattern and left primordial gravity waves as the only plausible explanation. “This has been like looking for a needle in a haystack but instead we found a crowbar,” commented Clem Pryke of the University of Minnesota.
Scientists will be looking to the next release of Planck satellite data later this year, which will include polarisation analysis, to confirm – or possibly disprove – the Bicep 2 discovery. Then they will be able to build confidently on inflationary theory as the basis of cosmology.
