On March 17 a team of astrophysicists working on the Background Imaging of the Cosmic Extragalactic Polarization (BICEP2) experiment announced the discovery of gravitational waves. These waves are, as their name suggests, ripples in space-time caused by gravity that propagates outwards from a source.
Until now, gravitational waves were considered a theoretical concept, originally predicted in 1916 by Einstein in his general theory of relativity and subsequently in the 1980s by Alan Guth and several others in the theory of inflation. The discovery has galvanized the scientific community, with many hailing it as the first direct evidence of the Big Bang—the theory that the entire universe sprung into existence by expanding outwards from an infinitesimally small point approximately 13.8 billion years ago.
The team made the discovery by meticulously pouring over data on the cosmic microwave background (residual radiation thought to be left over from the Big Bang that permeates the known universe as “background noise”) gathered from 2010-2012 by BICEP2. BICEP2 is a powerful radio telescope located at the Amundsen-Scott South Pole Station in Antarctica. The team was looking for evidence of B-mode polarization in the CMB.
Basically, as the gravitational waves caused by inflation passed through the early universe, they set charged particles into motion, which imprint a particular pattern on the CMB by polarizing it. The periodic motion of the charged particles makes the electromagnetic waves of the CMB oscillate in particular directions, the pattern of which (pictured above) looks sort of like a map of wind currents, with tiny vortexes spinning in different directions. Now that the team’s work has been published it will most certainly be heavily scrutinized by the rest of the scientific community, but the general consensus so far seems to be that the data will hold up.
In terms of scientific significance, it is difficult to overstate the impact of this discovery. This is easily one of the most exciting discoveries in astrophysics in decades. It is already being compared to the discovery of the Higgs boson by CERN in 2012, and there is talk of a Nobel Prize for the team.
Although the evidence for the Big Bang’s existence was already heavily in its favour, this provides the first tangible, direct evidence that it actually happened, and opens the door to further study of the early universe. This could tell scientists more about how matter and energy behave in conditions much hotter and denser than those found anywhere in the cosmos, helping to answer many remaining questions about the exact nature of gravity and how it interacts with the other fundamental forces of the universe.
Overall, this is a phenomenally exciting discovery, the significance and potential implications of which I can only do so much to convey in the limited space provided here; as Carl Sagan once said: “Somewhere, something incredible is waiting to be known,” and this discovery puts us one step closer to finding the answers to some of the oldest, and most significant questions in the universe.