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Physics + MathPhysics & Math

First Direct Evidence of Cosmic Inflation

ByKate BeckerThe Nature of RealityThe Nature of Reality

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When Alan Guth proposed the theory of cosmic inflation almost 35 years ago, he wondered whether it would ever be possible to prove his hypothesis that the universe ballooned up exponentially in the first moments after the Big Bang. There was ample indirect evidence : the universe’s surprisingly uniform temperature, the apparent “flatness” of spacetime, and the conspicuous absence of magnetic monopoles. In the years that followed, astronomers used satellites like WMAP and Planck to search for echoes of the inflationary era in the cosmic microwave background radiation. Their results lined up with many inflationary predictions, but fell short of being the “smoking gun” that would have had Guth and other theorists popping their champagne.

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Well, bring on the bubbly: Using a telescope called BICEP2 , a team of astronomers led by John Kovac (Harvard-Smithsonian Center for Astrophysics) has detected a polarization pattern in the microwave background radiation that is the first direct evidence for cosmic inflation. This “B-mode” polarization is a “twisty” pattern created by gravitational waves. The discovery is also the first direct image of gravitational waves.

The 10-meter South Pole Telescope and the BICEP (Background Imaging of Cosmic Extragalactic Polarization) Telescope at Amundsen-Scott South Pole Station. Credit: Keith Vanderlinde, National Science Foundation

The news is generating plenty of buzz. Here are our picks from some of the best coverage we’ve seen so far:

Nature : How astronomers saw gravitational waves from the Big Bang
A suite of special coverage, including an explainer on gravitational waves and an interview with John Kovac, who maintains that he, for one, has held off on the champagne:

My role in this process has been to remain calm at all times. The time to celebrate, I think, will be once we have published our results and presented them to the scientific community.

The New York Times : Detection of Waves in Space Buttresses Landmark Theory of Big Bang

Dennis Overbye talks (or emails) with everyone-who’s-anyone as he traces the history of inflationary theory from its inception in 1979 to its greatest confirmation yet today, closing with the possibility that inflation is continuing elsewhere in the cosmos:

Most of the hundred or so models that have been spawned by Dr. Guth’s original vision suggest that inflation, once started, is eternal. Even as our own universe settled down to a comfortable homey expansion with atoms, stars and planets, the rest of the cosmos will continue blowing up, spinning off other bubbles here and there endlessly, a concept known as the multiverse.

WIRED : Cosmologists Finally Capture an Elusive Signal From the Beginning of Time

Adam Mann explains “how primordial B-modes could be so important if you’ve never heard of them” and highlights the need for followup observations to confirm the result:

In fact, BICEP’s data is somewhat at odds with other experiments, such as the Planck space telescope, which have carefully mapped the CMB but not seen primordial B-modes. But it’s also possible that these other teams simply missed what BICEP is seeing and, now that they know how to look for the primordial B-modes, can confirm the results fairly quickly using already existing datasets, perhaps within a matter of weeks. No doubt, other collaborations will begin taking new data to try and detect the primordial B-modes on their own.

Sky and Telescope : Proof of Inflationary Universe To Be Announced Today?

In advance of today’s announcement, Sky and Telescope’s Alan MacRobert rounded up coverage of the search for B-modes and explained what B-modes are and how gravitational waves create them.