Earlier this year, scientists from a group called Bicep reported one of the greatest scientific discoveries in years: direct evidence of gravitational waves that are the result of cosmic inflation, a long theorized event that happened after the Big Bang that created the Universe.
Criticism met that announcement, particularly when part of those observations could have been interstellar dust, that stuff that often gets in the way when measuring things in space. Now that criticism is even louder, thanks to new observations by the European Space Agency's Planck satellite, which detected a great deal more dust over the area observed than previously presumed.
Gravitational waves are ripples in space-time and are remnants of the rapid expansion of the Universe that took place after the Big Bang. We've never found direct evidence of them before, so the announcement of their discovery took the world by storm. However, as is often the case with science, other scientists challenged the discovery. Now, Planck's results add doubt to the initial find.
Dust is an astronomer's worst enemy because it spins throughout space and creates noise in signals that are often misinterpreted. Although the Bicep team thought they were looking at one of the cleaner parts of the sky, it seems that no part of the sky is truly clean of interstellar dust. There's a very good chance that the signals the Bicep team took as gravitational waves were just dust.
"This is going to be a long march, but the goal of probing the earliest moments of the universe makes it well worth the effort," says Michael S. Turner, a cosmologist at the University of Chicago. "Dust is the bane of the existence of astrophysicists - and cosmologists. It is everywhere, and yet our understanding of it is very poor."
However, astronomers aren't giving up hope yet. There's still a chance that some of what Bicep detected were gravitational waves. It's up to the Bicep and Planck team to work together on future research.
"Planck has wider spectral coverage, and has mapped the entire sky; BICEP2 is more sensitive, but works at only one frequency and covers only a relatively small field of view," says Peter Coles from Sussex University. "Between them they may be able to identify an excess source of polarization over and above the foreground, so it is not impossible that a gravitational wave component may be isolated."
Regardless of the validity of Bicep's announcement, astronomers now believe that the team announced their discovery prematurely.
