Monday, 17 March 2014

First Direct Evidence of Cosmic Inflation

Swirls in the CMB polarization, shown here in the BICEP2 data, show the first clear evidence of primordial gravitational waves. Image: BICEP2

The title of the scientific presentation said it all:

"First Direct Evidence of Cosmic Inflation".

It appears that the rumours were true and BICEP2 has discovered something extraordinary.

The full set of scientific papers is online here:
The FAQ summarising the data is here:

Adam Mann reports:
"A team of scientists may have detected a twist in light from the early universe that could help explain how the universe began. Such a finding has been compared in significance to the detection of the Higgs boson at the LHC in 2012. What they detected is known as primordial B-mode polarization and is important for at least two reasons. It would be is the first detection of gravitational waves, which are predicted to exist under Einstein’s theory of relativity but have never before been seen. But the thing that has scientists really excited is that it could provide the first direct evidence for a theorized event called inflation that caused the universe to exponentially grow just a fraction of a fraction of a second after it was born."

“Detecting this signal is one of the most important goals in cosmology today.” noted astronomer, John Kovac, of Harvard, who led the team announcing the discovery.

Dr Jo Dunkley who has been searching through data from the European Planck space telescope for a B-mode signal, stated: "I can't tell you how exciting this is."

"Everything that is important, everything we see today - the galaxies, the stars, the planets - was imprinted at that moment, in less than a trillionth of a second. If this is confirmed, it's huge."

Alan Guth himself -one of the fathers of the theory of inflation - was cautiously optimistic about the initial announcement:
"No experiment should be taken too seriously until there's more than one that can vouch for it. But it does seem to me that this is a very reliable group and what they've seen is very definitive."

Later in the New York Times, Guth pronounced himself “bowled over,” saying he had not expected such a definite confirmation in his lifetime. “With nature, you have to be lucky,” he said. “Apparently we have been lucky.”

And here is the news being broken to theorist, Andrei Linde, another of key authors of the inflationary universe theory (as well as the theory of eternal inflation):


Max Tegmark, a cosmologist at MIT, told the New York Times, “I think that if this stays true, it will go down as one of the greatest discoveries in the history of science.” He added, “It’s a sensational breakthrough involving not only our cosmic origins, but also the nature of space.”

Nobel Prize winner, Frank Wilczek, commented: "Assuming the BICEP results are what they appear to be, it will be, like the Higgs particle: a triumph for boldness and minimalism."

This announcement has implications far beyond the field of cosmology.  If the detection is confirmed, and inflation theory is eventually accepted, particle physicists will also be intrigued.  According to inflation theory, a quantised particle called the inflaton exists, and is hypothesized to be responsible for cosmic inflation in the very early universe.  So as physicist Richard Easther, points out, "we're not just looking at the beginning of the universe, we are exploring undiscovered vistas in particle physics."

The BICEP - (Background Imaging of Cosmic Extragalactic Polarization) telescope, Antarctica

Meanwhile, one of the hottest debates in the coming days and weeks is what these results mean for cosmological models which involve the existence of the Multiverse.  Even before the press conference was finished, early comments were being made.

Sean Carroll remarked:
"I'm less sure than Guth & Linde on the inflation -> multiverse connection. But inflation certainly strengthens the case for a multiverse."

Whatever way you look at it, today has been a truly historic day for physics, and has ushered in a new era of scientific enquiry.  The days, weeks and months ahead promise to be captivating, as physicists strive to comprehend the significance of these new findings.

Initial media reactions:

Primordial Gravitational Waves and Cosmic Inflation

Today might turn out to be a historic day for the field of cosmology.  At 16:00 UTC at the at Harvard-Smithsonian Center for Astrophysics, physicists will be announcing what they are describing as a "major discovery".

Since the news of the announcement broke last week, the cosmology community has been awash with rumours as to what the discovery might be.

Most cosmologists now believe the announcement will concern the detection of gravitational waves in the polarization of the cosmic microwave background radiation, by an experiment called BICEP2, based near the South Pole in Antarctica.

If this is the case, it has wide-ranging implications for our understanding of the early universe.  Detection of these primordial gravitational waves would be the best evidence yet that cosmic inflation occurred, shortly after the Big Bang.  It would strongly support the theory of inflation, posited by Alan Guth, Andrei Linde and others, and developed by a generation of theoretical cosmologists.

Until 1600 UTC today, we won't know for sure, but it is clear that the cosmology community believe the announcement will be highly significant. If evidence for gravitational waves is presented, it would be a pioneering discovery that would change the face of cosmology.

As noted physicist, Sean Carroll, writes:
"Other than finding life on other planets or directly detecting dark matter, I can't think of any other plausible near-term astrophysical discovery more important than this one for improving our understanding of the universe. It would be the biggest thing since dark energy."

Rumours began circulating shortly after a press release was issued last Wednesday. Cosmologist Richard Easther, of the University of Auckland, was amongst the first to pick up on the story, shortly followed by fellow New Zealander, Shaun Hotchkiss, who has been keeping an constantly updated list of posts and background reading material on his Trenches of Discovery blog.  The rumours centre on the supposed detection of "B-modes" at microwave lengths in the cosmic microwave background (CMB).  B-modes have been sought by physicists for years, as they are thought to be the best evidence that a period of inflation occurred immediately after the Big Bang.  If detected, as Phillip Gibbs at viXra notes, "this would be a very big deal indeed because it could be a direct experimental hook into the physics of inflation and even quantum gravity. These are of course the least well understood and most exciting unchartered waters of fundamental physics. Any observation that could provide phenomenology for these areas would be the greatest empirical discovery for the foundations of our universe for decades."

But he urges caution about assessing the implications of the announcement, stressing that, "the new result ... will be scrutinised, not least by rival astronomers from the SPT and Polarbear observatories who only managed to detect lensing B-modes. Why would BICEP2 succeed where they failed? Can they be sure that they correctly subtracted the background? These questions are premature and even immature before we hear the announcement, but it is good to go along prepared for the kind of questions that may need to be asked."

BICEP - (Background Imaging of Cosmic Extragalactic Polarization), Antartica

If the rumours are true, the announcement has major significance for the theory of cosmic inflation. As Hotchkiss writes:
"Inflation is a compelling theory, not without some problems, for how the universe evolved in its very earliest stages. If it occurred when the universe had a large enough temperature, it would generate primordial gravitational waves large enough to tickle the CMB enough to make these B-modes visible in the polarisation."

Hiranya Peiris, a cosmologist from University College London emphasises the point by noting:
"The primordial gravitational waves have long been thought to be the smoking gun of inflation. It's as close to a proof of that theory as you are going to get."

Cosmologists believe that only inflation would amplify the primordial gravitational waves into a detectable signal. If BICEP2 has found such a signal, this will be a very big day indeed.