GRAV WAVE DRAMA: 'Big Bang echo' may have been grit on the scanner – boffins

Exit Planet Dust on faster-than-light expansion of universe

Data from the European Space Agency's Planck satellite has cast doubt over the claimed discovery of a gravitational wave tsunami sweeping the universe from the Big Bang.

In March, a team of astrophysicists running the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) observatory shocked the scientific establishment with the announcement that they had not only spotted the remains of the waves formed in the first fractions of a second after the Big Bang, but also that the measurements confirmed Andrei Linde's theory of cosmic inflation – that for a few moments the expansion of space exceeded the speed of light.

While Linde was somewhat overcome when he heard the news, the rest of the scientific community has been hard at work scrutinizing the data, as you'd expect. Some doubts were raised, and now this latest paper [PDF] from the Planck team suggests the results are very much in question.

The BICEP2 telescope, placed near Earth's South Pole, used a technique called B-mode polarization to measure the cosmic microwave background (CMB) radiation. The BICEP2 team said the signal they picked up was so large that gravitational waves must be the cause – but the Planck boffins say the amount of space dust in range of the telescope was massively underestimated, and this could affect its readings.

"We show that even in the faintest dust-emitting regions there are no 'clean' windows in the sky where primordial CMB B-mode polarization measurements could be made without subtraction of foreground emission," the team's paper states.

The new findings don't totally invalidate the BICEP2 findings; it just makes the task of analyzing its data much more complicated. The two groups will together go over the numbers again, with the new dust readings taken into account, to see if the detected gravitational wave tsunami was truly caused by the birth of the universe.

"It's not completely definitive - but it's pretty powerful. BICEP2 did indeed observe the signal that they said they observed; but the smart money right now is betting that the signal didn't come from the early universe," blogged physicist Sean Carroll of Caltech.

"There's still work to be done, and the universe has plenty of capacity for surprising us, but for the moment we can't claim to have gathered information from quite as early in the history of the universe as we had hoped." ®


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