On March 17, 2014, a consortium led by Harvard-Smithsonian Center for Astrophysics announced the detection of twisted “B-mode” polarization in the Cosmic Microwave Background.
This extraordinary discovery is the first direct confirmation of inflation theory, which describes how the universe expanded exponentially in the first tiny moments after the big bang.
If it holds up, it’s almost definitely a Nobel Prize winner.
What BICEP2 Saw
The BICEP2 (Background Imaging of Cosmic Extragalactic Polarization) telescope collected data from January 2010 to December 2012 at the Amundsen–Scott South Pole Station. According to the Cambridge, MA press release:
“The South Pole is the closest you can get to space and still be on the ground,” said John Kovac (Harvard-Smithsonian Center for Astrophysics), leader of the BICEP2 collaboration. “It’s one of the driest and clearest locations on Earth, perfect for observing the faint microwaves from the Big Bang.
The telescope recorded differences in the Cosmic Microwave Background in a small patch of the sky in two perpendicular orientations. (The Cosmic Microwave Background is the residual radiation from some 380,000 years after the big bang.)
Per the press release: “Our team hunted for a special type of polarization called ‘B-modes,’ which represents a twisting or ‘curl’ pattern in the polarized orientations of the ancient light,” said co-leader Jamie Bock (Caltech/JPL). (Polarization is the orientation of light waves.)
Called the Holy Grail of cosmology, B-mode polarization is a key prediction of inflation theory. The polarization signals came through about a factor of two more strongly than expected. This should help physicists narrow down the number of inflation models, and perhaps lead to new physics.
Inflation and the Big Bang
Inflation theory is a modification to the big bang theory developed in the 1980’s by physicist Alan Guth (and others). It proposes that one billionth of a trillionth of a trillionth of a second after the big bang, our universe expanded exponentially. As a result, our cosmos grew more than a 1078 times — that’s 1 with seventy-eight zeros — in less time than the blink of a blink of a blink of an eye. This is like almost instantaneously scaling a molecule of DNA to roughly the size of the Milky Way galaxy.
Why have most cosmologists come to accept this wild theory?
Because it explains two observations which the original big bang theory could not. The first is the striking temperature uniformity of the Cosmic Microwave Background — to one part in 100,000 over the entire sky.
Inflation theory’s explanation is that at the very beginning of the universe, space expanded slowly. This allowed temperatures to be broadly established. Inflation then occurred and expanded this uniformity to the immense cosmos we see today.
The second is why the geometry of the observable universe is flat or nearly flat. As I explain in my recently-published book,”Inflation stretched space by such an enormous factor that our visible universe today is but a tiny pinpoint within a gigantic cosmos. Even though the geometry of the entire universe may be curved, the visible universe — the part we can see — appears flat.”
Inflation also explains why certain parts of the universe contain galaxies and galaxy clusters, while other parts are mostly empty. In the pre-inflation universe, random quantum fluctuations at microscopic levels produced tiny variations in the density of matter and energy.
Inflation rapidly expanded these differences in density to cosmic size. Areas of greater mass/energy density came together under gravity to form the galaxies, clusters, and the cosmic web we see today.
Primordial Gravity Waves
Inflation theory predicts the enormous hyper-expansion of space produced primordial gravitational waves — ripples in the fabric of spacetime. This in turn caused the unique twisted polarization patterns called B-modes in the Cosmic Microwave Background.
Per the press release:: “The swirly B-mode pattern is a unique signature of gravitational waves because of their handedness. This is the first direct image of gravitational waves across the primordial sky,” said co-leader Chao-Lin Kuo (Stanford/SLAC).
New Information About the Universe
Marc Kamionkowski, professor of physics and astronomy at Johns Hopkins University, predicted how to find these gravitational wave effects on the Cosmic Microwave Background in 1997. “This is huge,” Kamionkowski told Scientific American. “It’s not every day that you wake up and find out something completely new about the early universe. To me this is as Nobel Prize–worthy as it gets.”