First tremors of big bang detected in ‘new era’ for physics

[faisal6309]

First tremors of big bang detected in ‘new era’ for physics

Scientists have heralded a “whole new era” in physics with the detection of “primordial gravitational waves” - the first tremors of the big bang.

The minuscule ripples in space-time are the last prediction of Albert Einstein’s 1916 general theory of relativity to be verified. Until now, there has only been circumstantial evidence of their existence. The discovery also provides a deep connection between general relativity and quantum mechanics, another central pillar of physics.

“This is a genuine breakthrough,” says Andrew Pontzen, a cosmologist from University College London who was not involved in the work. “It represents a whole new era in cosmology and physics as well.” If the discovery is confirmed, it will almost certainly lead to a Nobel Prize.

The detection, which has yet to be published in a peer-reviewed scientific journal, was announced yesterday at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and comes from the Background Imaging of Cosmic Extragalactic Polarization 2 (Bicep2) experiment - a telescope at the South Pole.

The detection also provides the first direct evidence for a long-held hypothesis called inflation. This states that a fraction of a second after the big bang, the universe was driven to expand hugely. Without this sudden growth spurt, the gravitational waves would not have been amplified enough to be visible.

“Detecting this signal is one of the most important goals in cosmology today. A lot of work by a lot of people has led up to this point,” said John Kovac of the Harvard-Smithsonian Center for Astrophysics, who leads the BICEP2 collaboration.

The primordial gravitational waves were visible because they created a twisting pattern called polarisation in light from the big bang. Polarisation is the direction in which a light wave oscillates. It is invisible to human eyes, which only register brightness and colour. Sunglasses made from polaroid sheets work by blocking out all light waves except those with a specific polarisation.

Light from the big bang has been turned into microwaves by its passage across space. These microwaves were discovered in 1964 and are known as the cosmic microwave background radiation. Bicep2 was designed to measure their polarisation.

Rumours began on Friday that the detection of primordial gravitational waves would be announced. It had been thought that a gravitational wave signal would have to be surprisingly strong to be detected by the current technology used in ground-based detectors.

The Bicep2 team have spent three years analysing the signal in order to be certain. “This has been like looking for a needle in a haystack, but instead we found a crowbar,” said co-leader Clem Pryke of the University of Minnesota.

Nevertheless, the signal will have to be confirmed. “I think a lot of people will be looking very critically at this,” says Pontzen.

Confirmation could come as early as August. The European Space Agency’s Planck satellite has been looking for this same signal and is due to announce its findings.

Whereas Bicep2 has only looked at part of the sky visible from the south pole, Planck has mapped the whole sky.

If it confirms the signal and its strength then cosmologists will be presented with an extraordinarily rich seam of data about the conditions immediately after the big bang. “We are going to be able to measure all sorts of subtle details to start pinning down how physics operates in those utterly extreme conditions,” says Pontzen.

This could reveal the interface between the two great theories of physics: general relativity and quantum mechanics. Despite almost a century of effort, the world’s physicists have not been able to show how these theories work together. The primordial gravitational waves that produced the signal seen by Bicep2 were produced in interactions that took place at a trillion times the energies that can be produced in the Large Hadron Collider at Cern.

“This is like turning the whole universe into a particle physics experiment,” said Hiranya Peiris, a cosmologist from University College London.

It could even show them the way to join the two theories together, producing what is sometimes called “the theory of everything”.

“Gravitational waves emitted at the time of the big bang can tell us how the universe came to exist,” said Dr Ed Daw, an astronomer at the University of Sheffield. “If these results prove correct, we will have new key information on the very early universe, information that is hard to get from any other source.

“Gravitational waves are a new frontier in astrophysics and cosmology. If [YESTERDAY’S]findings are accurate then it will further strengthen our understanding of how the universe formed.”

Guardian

First tremors of big bang detected in ‘new era’ for physics - Science News | Daily News from The Irish Times - Tue, Mar 18, 2014

 

[Saifullah Sani]

First Direct Evidence of Cosmic Inflation

Almost 14 billion years ago, the universe we inhabit burst into existence in an extraordinary event that initiated the Big Bang. In the first fleeting fraction of a second, the universe expanded exponentially, stretching far beyond the view of our best telescopes. All this, of course, was just theory.

Researchers from the BICEP2 collaboration today announced the first direct evidence for this cosmic inflation. Their data also represent the first images of gravitational waves, or ripples in space-time. These waves have been described as the "first tremors of the Big Bang." Finally, the data confirm a deep connection between quantum mechanics and general relativity.

"Detecting this signal is one of the most important goals in cosmology today. A lot of work by a lot of people has led up to this point," said John Kovac (Harvard-Smithsonian Center for Astrophysics), leader of the BICEP2 collaboration.

These groundbreaking results came from observations by the BICEP2 telescope of the cosmic microwave background -- a faint glow left over from the Big Bang. Tiny fluctuations in this afterglow provide clues to conditions in the early universe. For example, small differences in temperature across the sky show where parts of the universe were denser, eventually condensing into galaxies and galactic clusters.

Since the cosmic microwave background is a form of light, it exhibits all the properties of light, including polarization. On Earth, sunlight is scattered by the atmosphere and becomes polarized, which is why polarized sunglasses help reduce glare. In space, the cosmic microwave background was scattered by atoms and electrons and became polarized too.

"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).

Gravitational waves squeeze space as they travel, and this squeezing produces a distinct pattern in the cosmic microwave background. Gravitational waves have a "handedness," much like light waves, and can have left- and right-handed polarizations.

"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).

The team examined spatial scales on the sky spanning about one to five degrees (two to ten times the width of the full Moon). To do this, they traveled to the South Pole to take advantage of its cold, dry, stable air.

"The South Pole is the closest you can get to space and still be on the ground," said Kovac. "It's one of the driest and clearest locations on Earth, perfect for observing the faint microwaves from the Big Bang."

They were surprised to detect a B-mode polarization signal considerably stronger than many cosmologists expected. The team analyzed their data for more than three years in an effort to rule out any errors. They also considered whether dust in our galaxy could produce the observed pattern, but the data suggest this is highly unlikely.

"This has been like looking for a needle in a haystack, but instead we found a crowbar," said co-leader Clem Pryke (University of Minnesota).

When asked to comment on the implications of this discovery, Harvard theorist Avi Loeb said, "This work offers new insights into some of our most basic questions: Why do we exist? How did the universe begin? These results are not only a smoking gun for inflation, they also tell us when inflation took place and how powerful the process was."

BICEP2 is the second stage of a coordinated program, the BICEP and Keck Array experiments, which has a co-PI structure. The four PIs are John Kovac (Harvard), Clem Pryke (UMN), Jamie Bock (Caltech/JPL), and Chao-Lin Kuo (Stanford/SLAC). All have worked together on the present result, along with talented teams of students and scientists. Other major collaborating institutions for BICEP2 include the University of California at San Diego, the University of British Columbia, the National Institute of Standards and Technology, the University of Toronto, Cardiff University, Commissariat à l'Energie Atomique.

BICEP2 is funded by the National Science Foundation (NSF). NSF also runs the South Pole Station where BICEP2 and the other telescopes used in this work are located. The Keck Foundation also contributed major funding for the construction of the team’s telescopes. NASA, JPL, and the Moore Foundation generously supported the development of the ultra-sensitive detector arrays that made these measurements possible.

Technical details and journal papers can be found on the BICEP2 release website:

BICEP2 2014 Results Release
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

First Direct Evidence of Cosmic Inflation | www.cfa.harvard.edu/