Antarctica's South Pole telescope, with the shimmering lights of the aurora australis in the background.
Credit: Steve Padin/International Polar Foundation
SYDNEY: Astronomers will put their theory of the origin and inflation of the universe to a stringent test by observing the cosmic background of the Big Bang in the extreme cold of Antarctica.
An international team are planning to use the 10-metre South Pole Telescope at the U.S. National Science Foundation's research station in the continent's central polar region. They will use it to look for gravity waves; stirrings in the fabric of space-time first predicted by Einstein.
Direct evidence of the early moments of the universe is shielded by the pervasive leftover glow of photons created early in the history of the universe. This glow, called Cosmic Microwave Background (CMB) radiation represents a moment in time about 380,000 years after the Big Bang when the universe first became transparent.
The beginning of everything
The CMB shields observations of the universe to the electromagnetic spectrum – visible light, infrared and so on – because before the CMB was created, the universe was opaque. Therefore, if we look across the universe by observing the electromagnetic spectrum, there is a limit to how far back we can see.
In theory though, gravity waves should pass through this barrier, since they pass through everything. Experts therefore believe that gravity waves should be able to provide crucial clues as to what was happening in the very first moments of the universe's existence.
Because they should be able to reveal this very early period of the universe's history, the phenomenon could finally provide proof for what astronomers suspect happened in these first few moments of existence.
It's thought that universe expanded dramatically trillionths of seconds after the Big Bang and then slowed down, a period known as inflation. Inflation helps explain away some problematic issues arising from the Big Bang theory, such as why the universe is flat (rather than curved) and why it looks the same in every direction.
Three places to look
"If you detect gravity waves, it tells you a whole lot about inflation for our universe," said cosmologist John Carlstrom, from the University of Chicago in Illinois.
Carlstrom announced the polar scheme on Monday at the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago, along with cosmologist Scott Dodelson from the University of Chicago and Fermilab Centre for Particle Astrophysics in Batavia, Illinois.
Theory says gravity waves occur at three frequencies: at one cycle in the lifetime of the universe, at one cycle per hour, and at audio frequencies. The Laser Interferometer Gravitational Wave Observatory (LIGO) is the main ground-based effort at the California Institute of Technology in Pasadena, and the Massachusetts Institute of Technology in Boston and focuses its search on the audio frequency band.
NASA/ESA's collaboration, Laser Interferometry in Space (LISA), plans to search for the one-cycle-per-second frequency waves by beaming a laser across from three spacecraft set in a triangle five million kilometres in perimeter.
Each spacecraft houses a precision-modelled cube that checks the distance between the spacecraft – any regular fluctuations could reveal the presence of gravity waves. The vast distance is needed because the effect of the waves would be very small. The launch of the three spacecraft is set for 2018.
The new South Pole Telescope scheme will search for the lowest frequency gravity waves. So low in frequency are these waves that there has only been one wave at this frequency once in the universe – and this one wave may have left evidence of its passage in the way light moves through the CMB.
Race to holy grail
Because of the extreme cold, and the clarity of the atmosphere at the poles, Antarctica is one of the few places on Earth where skies are exceptionally transparent to submillimetre wavelengths, which offers the best glimpse into the CMB.
"We should be able to see [gravity waves] if John's instruments are sensitive enough," Dodelson said.
David Blair, director of the Australian International Gravitational Research Centre at the University of Western Australia, in Perth, said that because the SPT will focus on the lowest frequency gravity wave, any results would be "controversial" as it would be hard to prove any effect observed was definitely from this once-in-the-lifetime-of-the-universe event.
"Gravity waves can go through everything, and because of that they are very hard to detect," said Blair who was not involved in the study. "Gravity waves are the only method by which we can see into the moment of creation. It's the holy grail."
