For the first time, scientists have found primordial gravitational waves — long-sought evidence of cosmic inflation theory.
Cosmic inflation suggests that the universe expanded at many times the speed of light a fraction of a second just after the Big Bang. These newly-discovered gravitational waves are ripples in space-time buried deep in the cosmic microwave background radiation, ancient light that permeated the known universe 380,000 years after the universe came into existence.
But why should we care? Here are five reasons the new cosmology findings announced Monday (March 17) should matter to Earthlings everywhere:
1) We all live in the universe
While this particular study might not have a huge practical impact on daily life, it does better explain our place in the universe. By directly detecting gravitational waves for the first time, scientists now have more evidence for cosmic inflation — the theory that space-time expanded faster than the speed of light just after the Big Bang. If scientists can nail down the nitty-gritty of cosmic inflation, they might be able to work backwards even further to find out what set off the Big Bang in the first place. [Cosmic Inflation and Gravitational Waves: Discovery Images]
2) … Well, make that a multiverse
The new results hint that our universe might just be one of many. According to some scientists, if cosmic inflation theory holds up, it would mean that the extreme expansion of space-time a fraction of a second after the Big Bang could have created small "bubbles" of universes in the fabric of the cosmos. Each of the universes could have their own weird laws of physics.
"In most of the models of inflation, if inflation is there, then the multiverse is there," Stanford University theoretical physicist Andrei Linde, who wasn't involved in the new study, said a news conference Monday (March 17). "It's possible to invent models of inflation that do not allow [a] multiverse, but it's difficult. Every experiment that brings better credence to inflationary theory brings us much closer to hints that the multiverse is real."
3) Testing the last untested part of Einstein's theory of general relativity
Gravitational waves were the last untested part of Albert Einstein's theory of general relativity. Scientists had long predicted their existence, but these direct measurements show that they do, in fact exist. The period of rapid cosmic inflation just after the Big Bang caused space-time to ripple, leaving its signature in the cosmic background radiation that can be seen throughout the universe.
4) Implications for grand unified theories
The new finding might also be a step closer to solving a major riddle in modern physics. At the moment, the theory that describes huge things (general relativity) and the idea that describes tiny things (quantum mechanics) aren't compatible. They both work on their separate scales, but when combined, they don’t play well together. If confirmed, the new study could move scientists closer to unifying those complicated theories.
"Right now, I think what we have are hints," Marc Kamionkowski, a physics an astronomy professor at Johns Hopkins University who is unaffiliated with the study, said Monday. "All we can tell now, is that the energy density is comparable to what you would expect from grand unified theories. We can't really say anything beyond that right now. We can't say anything about the details about grand unified theories.
"In the future, if this signal is confirmed, and extended, we will have not only the energy density of the universe at one particular time during inflation, but at a multiple set of time," he added. "We'll begin to learn something else about how inflation evolved, and then perhaps begin to learn more about the physics that had given rise to inflation."
5) It narrows down the models of inflation … by a lot
The different models that can be used to describe how inflation worked in the early universe have been significantly limited by the new research, an exciting idea for physicists in the field, Kamionkowski said.
"I think we've had good reason to believe, for a decade and a half, that predictions of inflation look quite a bit like what we see in the universe, but we've had many, many different models of inflation," Kamionkowski said. "Inflation, in some sense, is a paradigm or idea and there have been tons and tons of very speculative ideas for inflation."