Ripples of the multiverse

Waves from the big bang hint at something huge, finds Lisa Grossman
WAVE hello to the multiverse? Ripples in the very fabric of  the cosmos, unveiled this week, are allowing us to peer further back in time than anyone  thought possible, showing us what was happening in the first slivers of a second after the big bang. The discovery of these  primordial waves could solidify the idea that our young universe went through a rapid growth spurt called inflation. And  that theory is linked to the idea that the universe is constantly giving birth  to smaller “pocket” universes within an everexpanding multiverse. The waves in question are  called gravitational waves, and they appear in Einstein’s highly successful theory of general relativity (see “A surfer’s guide  to gravitational waves”, page 10). On 17 March, scientists working with the BICEP2 telescope in Antarctica announced the first indirect detection of primordial gravitational waves. This version of the ripples was predicted to  be visible in maps of the cosmic microwave background (CMB), the earliest light emitted in the universe, roughly 380,000 years after the big bang. The BICEP2 team had spent three years analysing CMB data, looking for a distinctive curling pattern called B-mode polarisation. These swirls indicate that the light of the CMB has been twisted, or polarised, into specific curling alignments. In two papers published online on the BICEP project website, the team said they have high confidence the B-mode pattern is there, and that they can rule out alternative explanations such as dust in our own galaxy, distortions caused by the gravity of other galaxies and errors introduced by the telescope itself. That suggests the swirls could have been left only by the very first gravitational waves being stretched out by inflation (see diagram, right). “This result would be the most important breakthrough in cosmology in 15 years” “If confirmed, this result would constitute the most important breakthrough in cosmology over the past 15 years. It will open a new window into the beginning of our universe and have fundamental implications for extensions of the standard model of physics,” says Avi Loeb at Harvard University.

If it is real, the signal will likely lead to a Nobel prize.” And for some theorists, simply proving that inflation happened at all would be a sign of the multiverse. “If inflation is there, the multiverse is there,” said Andrei Linde of Stanford University in California, who is not on the BICEP2 team and is one of the originators of inflationary theory. “Each observation that brings better credence to inflation brings us closer to establishing that the multiverse is real.