According to prevailing scientific wisdom, our universe burst into existence some 13.8 billion years ago, a monumental event now known as the Big Bang. Now, for the first time, scientists have found direct evidence to support the idea that within a fraction of a second after the Big Bang, the newly formed universe began to expand faster than the speed of light, increasing in size from a submicroscopic particle to roughly the size of a grapefruit in only an instant. This theory, known as “inflation,” helps explain why the universe appears so uniform, even in its most distant reaches.
Physicist Alan Guth of the Massachusetts Institute of Technology first proposed the inflation theory in 1979 as a way of reconciling some persistent mysteries about the Big Bang theory. Why, scientists wondered, did the heavens appear so uniform from pole to pole, and why were far-flung parts of the universe all found to have the same temperature? According to Guth’s theory, inflation occurred when the universe had been in existence for only a trillionth of a trillionth of a trillionth of a second. Such a rapid expansion, as the theory goes, would have smoothed out any unevenness or irregularities, after which the universe continued to expand over the next 14 billion years or so, up to the present day.
Though many scientists believed the inflation theory, they have been trying to find evidence of it for decades, without success. This week, however, a team of researchers announced that they had detected distinctive light-wave patterns in the microwave glow left over from the Big Bang, which is known as the Cosmic Microwave Background (CMB). They believe such swirls of light are evidence of the presence of gravitational waves, or ripples in the fabric of space-time, produced by inflation.
To collect the new findings, researchers from the Harvard-Smithsonian Center for Astrophysics, the University of Minnesota, Stanford University, the California Institute of Technology and NASA’s Jet Propulsion Laboratory used a telescope at the South Pole to scan a small portion of sky over three years. Their project, dubbed BICEP2, for Background Imaging of Cosmic Extragalactic Polarization, was seeking evidence of a phenomenon known as primordial B-mode polarization, or the twists of light in the CMB that could only have been produced by gravitational waves moving through the universe during the inflationary process. Such B-mode polarization has long been considered to be the “smoking gun” in support of the inflation theory.
Announcing the positive results of the BICEP2 project at a press conference earlier this week, John Kovac of the Harvard-Smithsonian Center for Astrophysics claimed that there is only a one in 10 million chance that his team’s results are a fluke. According to Kovac, “This is opening a window on what we believe to be a new regime of physics–the physics of what happened in the first unbelievably tiny fraction of a second in the universe.”
The team’s findings somewhat contradict other data, such as that collected by the Planck Space Telescope, which has mapped the CMB without finding evidence of primordial B-modes. Their results will have to be confirmed by other experiments, a standard requirement in the science world. If they are verified, however, the findings could amount to one of the biggest discoveries in the history of science. Marc Kamionkowski of Johns Hopkins University, who was not involved in the research, called the detection of the B-modes “huge, as big as it gets….This is a signal from the very earliest universe, sending a telegram encoded in gravitational waves.”