Evidence for cosmic inflation wanes | Science/AAAS | News

Evidence for cosmic inflation wanes | Science/AAAS | News: Now, researchers from the European Space Agency's Planck spacecraft have shown that radiation from dust in our galaxy accounts for some, and possibly all, of the BICEP signal.

Big Bang breakthrough team back-pedals on major result - physics-math - 19 June 2014 - New Scientist

Big Bang breakthrough team back-pedals on major result - physics-math - 19 June 2014 - New Scientist: The paper published today is significant because it is the first time the researchers themselves have dialled back on their original claims...

"It seems that real data from Planck is indicating that these dust models are under-estimates," says Pryke. "The prior knowledge of dust at these latitudes in our field of view has gone up and so the confidence in the gravitational wave component has gone down."

Backlash to Big Bang Discovery Gathers Steam - Scientific American

Backlash to Big Bang Discovery Gathers Steam - Scientific American: Spergel also says the BICEP2 team evidently failed to factor in contamination from the cosmic infrared background radiation that comes from distant, dusty galaxies. “When you do that,” Spergel says, “it’s probably enough to account for the entire signal they’re seeing.

Blockbuster Big Bang Result May Fizzle, Rumor Suggests | Science/AAAS | News

Blockbuster Big Bang Result May Fizzle, Rumor Suggests | Science/AAAS | News: To subtract the galactic foreground, BICEP researchers relied on a particular map of it generated by the European Space Agency's spacecraft Planck, which mapped the CMB across the entire sky from 2009 until last year. However, the BICEP team apparently interpreted the map as showing only the galactic emissions. In reality, it may also contain the largely unpolarized hazy glow from other galaxies, which has the effect of making the galactic microwaves coming from any particular point of the sky look less thoroughly polarized than they actually are. So using the map to strip out the galactic foreground may actually leave some of that foreground in the data where it could produce a spurious signal, Falkowski explains.

Cosmologists cast doubt on inflation evidence

Cosmologists cast doubt on inflation evidence: Inflation may very well be the cause—and Dent and company state right off the bat that "there is little doubt that inflation at the Grand Unified Scale is the best motivated source of such primordial waves" –  but there's also a possibility, however remote, that some other, later cosmic event is responsible for at least some if not all of the BICEP2 measurements.

Cosmologists Say Last Week’s Announcement About Gravitational Waves and Inflation May Be Wrong — The Physics arXiv Blog — Medium

Cosmologists Say Last Week’s Announcement About Gravitational Waves and Inflation May Be Wrong — The Physics arXiv Blog — Medium: Many cosmologists think that the same kind of phases changes occurred in the universe after inflation. Each phase change began in different regions at slightly different times...

This self-ordering process would have been hugely violent, generating its own gravitational waves that rippled through spacetime, albeit after inflation. Could this process be responsible for the polarisation that the BICEP2 team has measured?...

...a small improvement in the data could firmly rule out self-ordering as the origin of the signal.

First glimpse of big bang ripples from universe's birth - physics-math - 17 March 2014 - New Scientist

First glimpse of big bang ripples from universe's birth - physics-math - 17 March 2014 - New Scientist: Inflation should have stretched the very first gravitational waves created during the big bang, taking them from imperceptible wavelengths to a size we can detect in the CMB... Rippling gravitational waves would subtly change the polarisation pattern, twisting the CMB into distinctive swirls called B-modes...

"We see a big excess of power, and it looks exactly like the gravitational wave signal that we had been seeking," says Pryke. "There's a huge zoo of inflationary models, but if we look at the simplest ones, they would predict values in the ballpark that we're seeing..."

"If gravity were not quantised, inflation would not produce gravitational waves," says Guth.

Why I Still Doubt Inflation, in Spite of Gravitational Wave Findings | Cross-Check, Scientific American Blog Network

Why I Still Doubt Inflation, in Spite of Gravitational Wave Findings | Cross-Check, Scientific American Blog Network: ...inflation comes in so many different versions that it can give you “anything you want.” In other words, it cannot be falsified...

But here is what I’d like to see: First, corroboration of the BICEP2 findings by other groups and observatories. Second, experiments from high-energy physics that provide some sort of corroborating evidence of the driving mechanism of inflation. Third, an explanation of why the Alice’s Restaurant Problem isn’t still a problem. Fourth, an explanation of why only inflation, and not other more conventional physical phenomena, can account for the gravity-wave findings...