A leading British physicist has hailed the discovery of evidence of cosmic inflation as "the most significant discovery for years".
"It's hugely exciting," said Dr Chris Lintott, from Oxford University.
"It's exciting for observers because it provides a new window on a very early stage of the universe's evolution, and its exciting for theorists because we might now finally have a handle on what sort of thing caused inflation."
Above: the pattern of gravitational waves as discovered by the Harvard-Smithsonian team
He added: "At the moment there are lots of competing ideas but until now we haven't had the data to test them against.
"What's interesting is that the 'smoking gun' proved much more obvious than a lot of people thought it would be. It raises the possibility of several other experiments confirming the finding."
Direct evidence of inflation has some profound implications, said Dr Lintott. For instance, it points to a deep connection between the subatomic world of quantum mechanics and the cosmic-scale of general relativity.
At the quantum level, subatomic particles pop in and out of existence even in empty space.
Inflation may have blown up these quantum fluctuations, turning them into the seeds of galaxies.
Professor John Womersley, chief executive of the Science and Technology Facilities Council (STFC) which funds UK cosmology research, said:
"Modern cosmology is based on three underlying assumptions - inflation, dark matter and dark energy. We don't know what any of them actually are, but over the last few years we have seen increasingly strong evidence that they are real.Suggest a correction
"Today's announcement from the Bicep project continues that process. Inflation is the very rapid expansion of the very early universe that is one of the pillars of our understanding of cosmology. Without inflation we would not be here.
"A detection of primordial B-mode polarisation provides very strong evidence for inflation and, if the Bicep results are verified by other experiments, that will be what we have.
"With the recent confirmation of the existence of the Higgs boson and now the first direct evidence for inflation, these are very exciting times to be a physicist."