A light in the darkness can come from unexpected places. Unusual experiments for probing dark energy seem set to revolutionise our understanding of this mysterious force.
In Chicago last week, the world's largest meeting of cosmologists debated two of the forces that could push the universe apart: inflation, the proposed period of exponential expansion that the universe went through immediately after the big bang; and dark energy, the present-day force thought to be responsible for pushing the cosmos outward at an ever increasing rate.
The announcement in March that gravitational waves had been seen should essentially prove that inflation happened. But the results are on ice. The BICEP2 telescope team, which did the work, may have underestimated the impact of galactic dust on the signal. If real, the pattern of the waves they saw in the cosmic microwave background – the earliest light emitted in the universe – is the fingerprint of the universe's rapid expansion.
Astronomers and cosmologists at the International Conference on Particle Physics and Cosmology (COSMO) duked it out over how their models for the universe would be affected in two futures: one in which the results hold, the other in which dust blows them away.
"Everyone wants BICEP2 to be right," Will Kinney of the University at Buffalo, New York, told a packed auditorium. "Because if it is, we are going to be doing incredibly precise physics on the inflationary model within the foreseeable future. And it's going to be really cool."
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