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Physics + MathPhysics & Math

Inflation, Elation, Deflation: Reflecting on BICEP2

New data undermine the widely-publicized claim that the BICEP2 telescope detected signals from the era of cosmic inflation.

ByKate BeckerThe Nature of RealityThe Nature of Reality

Six months ago, astrophysicists working on an experiment called

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BICEP2 were celebrating what some called the discovery of the century : the
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detection of a specific polarization signature in the cosmic microwave background radiation that, interpreted conservatively, provided the most direct confirmation ever of cosmic inflation. Read more expansively, it was seen as evidence for the quantization of gravity and the existence of the multiverse.

Liquid Helium Delivery
A snowmobile carrying liquid helium arrives at BICEP2. Credit: Robert Schwarz, University of Minnesota

But it wasn’t long before scientists started raising questions about the result. The problem: inflation isn’t the only possible cause of the polarization signal. Most worrying to critics, nearby dust could create a similar pattern. Though the discovery team tried to account for that dust, they may have missed the mark. As Charles Choi wrote here on The Nature of Reality on May 27:

The controversy hinges on their handling of the dust emission, which relied on a preliminary map based on about 15 months of data from the European Space Agency’s Planck spacecraft. Falkowski noted the BICEP2 group might have misinterpreted the Planck data, thinking that it only contained emissions from the Milky Way when it also included unpolarized emissions from other galaxies. If the BICEP2 team did not account for this fact, they might have underestimated how polarized the foreground from the Milky Way actually was. This could mean the inflation signal the group thought it saw might only be a spurious result from Milky Way emissions.

Last month, new data released by the Planck team confirmed that all or most of the BICEP2 signal could indeed be due to dust . It doesn’t rule out the possibility that BICEP2 saw something real, but shows that the signal can’t yet be untangled from the noise.

All of which has scientists and science media wringing their hands over what—if anything—they should have done differently. The splashy announcement, accompanied by literal and figurative champagne-cork-popping, as we covered here , coincided not with publication in a peer-reviewed journal but with the publication of a results online. Should the authors have waited for peer review to announce their results? Should journalists have been more circumspect?

Here’s how the editors of Nature reacted in an October 14 editorial :

As we have pointed out before, researchers must not be afraid to be wrong. With hindsight they may feel they rushed to publish their claim too quickly, but professional science is a competitive and fast-moving field. The academic paper was cautious and the team’s reaction to subsequent criticism seems constructive. Some may question the timing of the announcement, made when the paper was released on the Internet, not accepted or published by a journal, but at least the evidence was there to examine. If the scientists and the media both largely acted properly, then what should be discussed at next week’s meeting [of the Council for the Advancement of Science Writing]? It could do worse than start by screening the celebratory online video produced by California’s Stanford University and released to accompany the announcement. Scientists and journalists can include as many academic caveats as they like, but the sounds and images of champagne corks popping tend to render such statements of caution just that — academic.

There is a deeper issue here: science not by press conference but presented as an event. What in reality is a long, messy and convoluted process of three steps forward and two steps back is too easily presented as giant leaps between states of confusion and blinding revelation. At the heart of this theatre is the artificial landmark of a peer-reviewed paper. Fixed print schedules and releases to journalists under embargo (with or without champagne videos) help to lend the impression that the publication of a paper is the final word on a question — the end-of-term report on a scientific project that details all that was achieved.

As BICEP2 clearly demonstrates, most science is a work in progress. Which is surely good news for scientists, who remain useful, and for science writers, who will always have something to cover.

It’s long been part of NOVA’s credo that “science is neither sacred lore nor secret ritual, but rather curious people exploring interesting questions.” Science is not a series of facts to be memorized, but a process, and that process includes missteps, dead ends, and course corrections. In an age of blogs, Twitter, and webstreamed press conference, scientific information flows more freely than ever between scientists and the public. Whether this openness will strengthen or undermine trust in the scientific process is an open question.

This project/research was supported by grant number FQXi-RFP-1822 from the Foundational Questions Institute and Fetzer Franklin Fund, a donor-advised fund of Silicon Valley Community Foundation.