The multiverse theory has been a hot topic of controversy, and a recent announcement from the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) experiment at the South Pole is sure to stir debate up again in what physicists are calling a breakthrough in the field. Imprints detected in the oldest light in the universe, the cosmic microwave background, resemble ripples dubbed gravitational waves with a pattern predicted by the theory of inflation. This in turn suggests that we live in a universe that is simply a “bubble in a glass of champagne.”
Inflation hypothesizes that the universe expanded exponentially in a matter of nanoseconds after the Big Bang. A part of this theory includes the fact that our universe is a small facet of an infinitely larger “megauniverse,” and that there are many more universes. This would be due to the fact that when the universe was expanding faster than the speed of light, “the expansion ripped the vacuum of spacetime into separate pieces, or multiple universes,” according to Scientific American. This gives rise to an increased speculation of the multiverse theory, one often dismissed as something impossible to test and scientifically irrelevant. Scientists are not sure why this large-scale inflation only lasted as long as it did, pointing to another area of future study.
The universe was only cool enough to emit light about 380,000 years after the Big Bang. At this point, light was fossilized as cosmic microwave background radiation, which is what scientists studied to observe the gravitational waves. Before this time, light could not travel without bumping into matter in the hot and dense universe. Only when it cooled were neutral atoms able to form and light could travel through space, yielding the muted glow throughout the sky that is the cosmic microwave background. The signal was actually discovered on accident in 1964 by two scientists who thought it was simply interference caused by pigeon droppings on their instruments.
These kinds of ripples could only be formed with extreme violence, according to MIT physicist Max Tegmark for The Huffington Post. This raised the question of what could have created waves of that magnitude, as there does not seem to be anything in the universe big enough to make them. Inflation answers this by predicting that the universe doubled its size every 0.00000000000000000000000000000000000001 seconds, through which the Big Bang emerged and enough energy was transferred to spawn the gravitational waves detected by BICEP2.
Furthermore, the signal detected is much stronger than what was expected in regard to previous research. As a result, many models of this theory have been rejected; however, new theories are now on the table. The signal has a curling pattern that, according to physicist Chao-Lin Kuo, who designed the detector, “can be created only by gravitational waves produced by inflation… we’ve found the smoking gun evidence for inflation and we’ve also produced the first image of gravitational waves across the sky.”
Further research and tests are needed to confirm anything, but if the inflation hypothesis continues to be supported, it invariably entails the probability of multiple universes with a myriad of conditions.
“There doesn’t seem to be anything unique about the event we call the Big Bang. It is a reproducible event that could and would happen again, and again, and again,” says MIT theoretical physicist Frank Wilczek.
The hypothesis also could provide answers to questions that have been asked for years. For instance, early inflation uniformly spread out heat that had been previously contained in a miniscule space. Thus irregularities would be “smoothed out,” characteristic of our universe, with matter spread relatively evenly when gravity acted as a repulsive force, keeping matter separate.
Additionally, this universe has seemed from a scientific perspective specifically conformed for life to exist, with the perfect cocktail of physical and biological constants—almost suggesting some sort of intelligent design. The odds that this was the only universe birthed by the Big Bang do not look promising. However, multiverse theory suggests that of the infinite number of universes created, a portion happened to have the right conditions to sustain life, and this happens to be one of them. Alan Guth, who first studied inflation in 1980, notes the discrepancy in what is known and what is observed, and the multiverse theory seems to shed some light in these unknown waters.
“That’s why we are seeing what we are seeing,” Guth said to National Geographic. “Not because we are special, but because we can.”
There is already competition to replicate BICEP2’s findings as well as to come up with an alternative explanation for the gravitational waves observed. Some clarity will be reached when the Planck satellite experiment releases polarized images of the cosmic plasma. Come what may, we have reached a frontier as mysterious and exciting as the infinite expanse we are trying to piece together.