Growing doubt that gravitational waves were actually detected

Nature has an article up describing the problems with the BICEP2 results that are now being identified by various scientists.  It’s actually the second one I’ve seen them publish on this.

The astronomers who this spring announced that they had evidence of primordial gravitational waves jumped the gun because they did not take into proper account a confounding effect of galactic dust, two new analyses suggest. Although further observations may yet find the signal to emerge from the noise, independent experts now say they no longer believe that the original data constituted significant evidence.

Researchers said in March that they had found a faint twisting pattern in the polarization of the cosmic microwave background (CMB), the Big Bang’s afterglow, using a South Pole-based radio telescope called BICEP2. This pattern, they said, was evidence for primordial gravitational waves, ripples in the fabric of space-time generated in the early Universe (see ‘Telescope captures view of gravitational waves‘). The announcement caused a sensation because it seemed to confirm the theory of cosmic inflation, which holds that the cosmos mushroomed in size during the first fraction of a second after the Big Bang.

However two independent analyses now suggest that those twisting patterns in the CMB polarization could just as easily be accounted for by dust in the Milky Way Galaxy^1, 2.

The BICEP2 team has reportedly been sticking to their guns, and many theoretical physicists initially downplayed the issues, so I’ve been reluctant to put too much credence to these stories.  But the doubts seem to be gaining more traction, and this caught my attention:

“I had thought that the result was very secure,” Alan Guth, the cosmologist who first proposed the concept of cosmic inflation in 1980, and who is at the Massachusetts Institute of Technology in Cambridge, told Nature after learning about Flauger’s talk. “Now the situation has changed.”

It’s still possible that when the BICEP2 team actually publishes their results, all of the issues will be addressed and results still found to be compelling.  But when the father of cosmic inflation loses confidence in the results, I’d say they’re on the ropes.  Inflation definitely may still be reality, but we might not have proof for it yet.