A new look at the Big Bang, moments later

CAMBRIDGE -- After days of rumors and anticipation, a team led by a Harvard astronomer announced Monday it had detected a pattern in the distant cosmos that reveals what happened in the first moments of the Big Bang 13.8 billion years ago: a hyper-expansion of our universe known as inflation.

The scientists also for the first time reported direct evidence of gravitational waves, which have been long predicted by Albert Einstein's general theory of relativity. It is also the first direct measurement of a type of radiation predicted by famed British cosmologist Stephen Hawking.

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'I think we can think of this measurement today as opening a new window up on what we believe to be a new regime of physics,' said John Kovac, an associate professor of astronomy at the Harvard-Smithsonian Center for Astrophysics who led the team. 'The physics of what happens in the first unbelievably tiny fraction of a second in the universe, and at extremely high energies.'

The presentation, in a packed auditorium at the Harvard-Smithsonian CFA, was packed with scientists wearing matching T-shirts with a map of the South Pole on the back, because that is where the telescope that made the measurement is located. Guest scientists wearing space-themed ties showed up, and an image of Rosie the Riveter was left near copies of the scientific papers, with the motto 'We can do it!' replaced by 'We detected it!'

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Since inflation was first proposed by Massachusetts Institute of Technology physicist Alan Guth in 1980, it has been an attractive, but unproven theory for the rapid expansion of the early universe. Guth describes it as the 'bang' of the Big Bang.

Inflation proposes that the initial expansion of the universe was caused by a repulsive form of gravity. The initial patch of the universe that underwent inflation would have been unbelievably small, about a billionth of the size of a proton, and then expanded exponentially. It was proposed because simpler models of the Big Bang could not explain some features of the universe, such as how uniform it is across the sky.

As Guth's initial idea has been refined and developed by other scientists over the years, its predictions seemed to be bearing out. But there was still no direct evidence for inflation and it was unclear whether the theory would ever have direct proof to bolster it. The energy needed to recreate the conditions in a particle accelerator were so high that it was unfeasible to think about recreating it. What inflation did predict, however, was a particular polarization pattern in the cosmic microwave background -- the faint light that is the afterglow of the Big Bang.

Using a telescope called BICEP2 based at the South Pole, the Harvard-led team claims to have detected a swirly polarization pattern, called B-mode polarization, in the faint light left over from the Big Bang. If confirmed by other experiments, it will be strong evidence of inflation and help guide scientists to which particular version of inflation is the correct one.

Guth said he learned the results when Kovac, the astrophysicist at the Harvard-Smithsonian Center for Astrophysics, e-mailed him to tell him he had some urgent news. Kovac came to Guth's office at MIT and disclosed the results last week.

'I was ecstatic,' said Guth. 'I hope this will sort of put the nail in the coffin, and define inflation as being the theory.'

Scientists hailed the discovery as a transformative moment in science -- one that will provide deep and complicated questions for physicists as well as transfix the imagination to the broader public, because it gives insight into a foundational question in phyics: how did the universe begin.

'I think this is one of the most important scientific discoveries of all time,' said Max Tegmark, a physicist from the Massachusetts Institute of Technology who was not involved in the work, but attended the packed presentation. 'It's just like when something big happens in your personal life and you keep waking up and saying, 'whoa!' I keep having these 'whoa!' moments. This is absolutely spectacular.'

Andrei Linde, a Stanford University physicist who developed Guth's theory further and put forth a version of inflation called chaotic inflation, said he was cautious because the discovery was so profound. He said the team that made the measurements is extremely strong, but as with all science, it must be repeated. If true, he said, the measurement is worthy of a Nobel Prize.

'The signal is compatible with models which I proposed a long time ago, so for me, this is fantastic news,' Linde said. 'For the general theory of relativity, for Einstein's theory, it's fantastic news because the gravitational waves is part of Einstein's theory, never seen -- just like the discovery of the Higgs boson was necessary for proving the standard model of particles.'

The scientists emphasized that they were eager to see other competing experiments confirm their results, and that a faster and more powerful version of the telescope will allow them to probe even further the polarization pattern to learn more about inflation.

Marc Kamionkowski, a physics and astronomy professor from Johns Hopkins University, called the new data 'cosmology's missing link -- not just a home run, but a grand slam.'

The discovery also comes at a historic time -- a half-century after a pair of scientists at Bell Labs first used a horn-shaped antenna on top of a hill in New Jersey to make measurements of microwave radiation. They saw a stubborn, noisy background signal in their data, and despite efforts to figure out how to get rid of it, it remained. Eventually, they realized it wasn't due to faulty equipment, but was actually the faint afterglow of the Big Bang.

That measurement spurred a revolution in cosmology, finally confirming that the universe had a discrete beginning -- and allowing scientists to discard the longstanding 'Steady State theory,' which said that the universe had always existed. It also sparked careful study of the cosmic microwave background, which has provided new insight into the structure and formation of our universe.

'I guess one can never rule out some other theory coming along which does something better, but this really seems to make a pretty tight story from very early time to now, and that's very satisfying,' said Robert W. Wilson, a Smithsonian astronomer who co-discovered the cosmic microwave background in 1964 at Bell Labs and shared the Nobel Prize for the work. 'I was a little bit skeptical of inflation, but now it looks like it's really a pretty tight fit.'