Last year, a team of scientists claimed they had made potentially one of the greatest scientific discoveries of the century, having finally picked up evidence for the Big Bang in the form of gravitational waves. Now, disappointedly, it seems that the breakthrough has turned to dust, as a new analysis of the results suggests that they were wrong.
Scientists have eagerly anticipated these results ever since doubt was raised shortly after the discovery was made. It was claimed that the team had not adequately excluded the possibility that the signal could have been caused by dust in our own Milky Way, and the scientists behind the discovery soon started to express reduced confidence in the findings as well.
In a bid to clear things up, the researchers, who had been using the BICEP2 telescope in the South Pole, agreed to collaborate with another team who had also been doggedly searching for the same thing: the Planck Consortium. The results from the pooled data were due to be released early next week, when the publication would have appeared on the pre-print server arXiv. However, the results were accidentally leaked on the website of one of the Planck satellite’s instrument teams. A summary of the work was posted on the French page, although it was removed shortly afterward.
“It’s been shown that the part played by the dust was significantly underestimated,” the scientists wrote.
The BICEP2 team’s initial results were exciting because it was believed that they had picked up signals from the very early universe in the form of gravitational waves. The BICEP2 telescope, located in the Antarctic, was gathering data on the afterglow of the Big Bang, or the cosmic microwave background (CMB). This is radiation from around 400,000 years after the universe first came into existence, making it the oldest light in the universe.
The BICEP2 team was looking for swirls in the polarization of the CMB, known as B-modes. These patterns are thought to be caused by gravitational waves; ripples in the fabric of space-time produced just a fraction of a second after the Big Bang. If the scientists managed to confirm their detection, then this would suggest that the early universe experienced rapid expansion, known as cosmic inflation.
Although scientists know what they are looking for, they are faced with several problems when trying to detect the waves. False signals can be produced when CMB passes through massive objects, such as large galaxies, which must be taken into consideration. Furthermore, dust from our own galaxy can also produce very similar patterns of polarization, which must be excluded from the data. While the BICEP2 team took into account all of the dust data that was available to them, the Planck team had managed to map the CMB using more frequencies than BICEP2, and hence picked up on false signals that were included in the original study.
While the new analysis doesn’t mean that gravitational waves are not there, it does mean that the BICEP2 team cannot claim their signal as detection of the waves as foreground signals cannot be excluded.
[Via BBC News and New Scientist]