Inflation at South Pole
New telescopes search universe for signs of rapid expansion after the Big Bang
Posted April 1, 2011
The theory of inflation holds that just a fraction of a second after the universe exploded into existence, it expanded exponentially, a burst of energy at a scale almost unfathomable to the human imagination.
The search for the evidence that will finally prove or disprove one of the key concepts of the Big Bang model of cosmology has similarly expanded in the last decade or so. John Kovac is proud to say that astronomers at the South Pole Station have been at the cutting edge of exploration into the microwave spectrum of the universe since almost the beginning.
“We’ve been very successful with cosmic microwave background observations here from the South Pole, particularly in the last 10 years,” said Kovac, an assistant professor of astronomy and physics at Harvard University , as his team readied the first of three receivers for a new telescope that will search for the telltale signature of inflation beginning this winter in Antarctica.
The project is called SPUD, an acronym that incorporates an acronym, for Small Polarimeter Upgrade for DASI. It will join forces in the Dark Sector at South Pole with a second-generation telescope called BICEP (Background Imaging of Cosmic Extragalactic Polarization) that sports a similar receiver.
Photo Credit: Peter Rejcek
The Dark Sector Lab at the South Pole houses BICEP2 and South Pole Telescope.
And with newer receivers and more telescopes planned in future years, experimental physicists believe they will soon be able to learn whether what we think we know about the universe from theorists is in fact reality. So far, so good, according to Kovac.
“It’s been an incredible success story in terms of the interplay between theory and observation, pushing out the frontiers of knowledge,” he said.
From the beginning
The theory about the formation of the universe is elegant. Designing the instruments to figure out if the theorists are on target — or have geeked out on one too many episodes of “Star Trek” — has been a slow but steady progression.
After all, there’s about 14 billion years to cover.
Remember that about 380,000 years after the spark that ignited the Big Bang, the universe cooled enough to allow electrons to combine with nuclei (what’s known as recombination). The universe glowed with light before recombination, but after recombination, it became transparent.
Fast forward about 14 billion years to today. The universe is still expanding — and thanks to another mystery called dark energy , that expansion is accelerating — though at a far slower pace than in its infancy.
The brilliant light from the Big Bang that started as ultra-high energy gamma rays stretched into X-rays, was visible light at recombination, and has now stretched all the way to microwaves.
In the 1960s, Arno Penzias and Robert Wilson of Bell Laboratories found microwave static interfering with a radio experiment. That interference — responsible for some television static — turned out to be remnant radiation from the birth of the universe: the so-called cosmic microwave background (CMB).
CMB radiation, often referred to as a faint hiss of microwaves, comes from every direction in the sky. It is almost a perfectly uniform plasma, with a temperature of 2.7 degrees above absolute zero on the Kelvin scale.
But it contains “hot” and “cold” spots that are slight irregularities in its near-perfect uniformity, which is known as anisotropy. These spots can tell cosmologists something about the geometry of the universe, the amounts and types of dark matter and energy that make up the cosmos, and even something about the universe’s ultimate fate.
The theorists had predicted anisotropy, but it was wasn’t until the 1990s that the experimentalists provided the first data to support the idea from NASA’s Cosmic Background Explorer (COBE) satellite. Many in the field of astrophysics mark those measurements in 1992 as the inception of cosmology as a precise science.1 2 3 Next