Less than 14 billion years ago, a hot and dense mass known as the initial singularity burst into the entire universe that we live in today. In less than a trillionth of a trillionth of a second, this mass expanded a distance of 45 billion light years, unfurling faster than the speed of light. While this event is commonly taught in academic classes, the notion of rapid expansion has all just been theory. No direct evidence linked this expansion to the Big Bang. However, some game changing evidence may have entered the field.
On March 17, researchers leading the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) project confirmed the existence of gravitational waves. These waves are thought to be the direct remnants of space inflation after the Big Bang.
The theory of the Big Bang, the nearly instantaneous inflation and birth of the universe, was first postulated in 1927 by Georges Lemaître. By studying Edwin Hubble’s observations that all distant galaxies appeared to be gaining distance from the Earth and Einstein’s theory of General Relativity, Lemaître was able to propose a unique mathematical explanation for the universe’s expansion. Lemaître soon realized that his model applied to the expansion of the known universe. A logical consequence, then, would be that the universe must have originated from a single mass during a precise epoch. Lemaître concluded that the universe emerged from the colossal expansion (not explosion, as the name suggests) of a single mass particle. This single particle created both space and time.
Although the name “Big Bang” was originally an insult to this idea from disagreeing physicists, Lemaître’s theory has been heavily developed over time and is currently accepted as one of the fundamental principles of the Standard Model of particle physics. But it is only with data that a theoretical model’s link to reality can be confirmed. After decades of searching, the answer has finally been found. One critical implication of the inflation model of the Big Bang theory is gravitational waves, whose invisible ripples metastasized through the universe. Much like the invisible Higgs field, these gravitational waves are difficult to measure, but gravitational waves had an effect on traveling light much like ripples in water.
After many years of searching, physicists of the BICEP2 project announced their discovery of primordial B-mode polarization, a type of cosmic microwave background (CMB) radiation. This remnant of the Big Bang, which until two weeks ago was only a theoretical concept, is a curl in the orientation of light. It is is a direct result of gravitational waves produced by inflation.
Moreover, the team detected a surprisingly high signal of gravitational waves, helping them rule out a plethora of alternative theories and narrow down the possible models of inflation dramatically. Most importantly, the discovery of gravitational waves discredits the popular cyclic model of the universe, which proposes that two three-dimensional universes lying in a higher dimensional space collided to produce the Big Bang. This theory cannot accommodate inflation or gravitational waves in its model.
To physicists worldwide, the inflation model of the Big Bang theory is now compelling not only from sheer mathematical elegance, but in its practicality supported by data that may finally forge the link between model and reality. Although the results of the BICEP2 team must be confirmed by other laboratories, there is now much better insight into what exactly happened in maelstrom of the universe’s first moments. While scientists have always been curious about the origin of all matter, space and time, the discovery of B-mode polarization brings us one small step closer to the truth of the birth of the universe.
