November 29, 2012
Scientists Offer New Insights Into Early Universe
Lee Rannals for redOrbit.com — Your Universe Online
Penn State University scientists using techniques from modern physics have developed a new understanding of the earliest eras in the history of the universe.The scientists now have an extended analyses that include quantum physics farther back in time than ever before, heading back to the very beginning.
The new paradigm of loop quantum origins show that the large-scale structures we see in the universe evolved from fundamental fluctuations in the essential quantum nature of "space-time."
"We humans always have yearned to understand more about the origin and evolution of our universe," Abhay Ashtekar, the senior author of the paper, published in the journal Physical Review Letters, said in a statement. "So it is an exciting time in our group right now, as we begin using our new paradigm to understand, in more detail, the dynamics that matter and geometry experienced during the earliest eras of the universe, including at the very beginning."
The new paradigm provides a conceptual and mathematical framework for describing the exotic "quantum-mechanical geometry of space-time" in the early universe. This paradigm shows that the universe was compressed to such unimaginable densities that its behavior was ruled not by the classical physics of Einstein's general theory of relativity, but by a more fundamental theory that incorporates strange dynamics of quantum mechanics.
In the quantum-mechanical environment, physical properties naturally would be vastly different from the way they are currently experienced. Ashtekar said these differences include the concept of "time," as well as the changing dynamics of various systems over time.
No space observatories have helped to detect anything as long ago and far away as the early eras of the universe, but a few have come close. Cosmic background radiation has been detected in an era of the universe when it was just 380 thousand years old. However, after that period, the universe had burst out into a much-diluted version of its earlier super-compressed self.
The density of the universe at the beginning of inflation was a trillion times less than during its infancy, so quantum factors are much less important in ruling the large-scale dynamics of matter and geometry.
Observing the cosmic background radiation shows that the universe had a predominantly uniform consistency after inflation.
The standard inflationary paradigm for describing the early universe treats space-time as a smooth continuum.
"The inflationary paradigm enjoys remarkable success in explaining the observed features of the cosmic background radiation. Yet this model is incomplete. It retains the idea that the universe burst forth from nothing in a Big Bang, which naturally results from the inability of the paradigm's general-relativity physics to describe extreme quantum-mechanical situations," Ivan Agullo, who worked on the research as well, said in a statement. "One needs a quantum theory of gravity, like loop quantum cosmology, to go beyond Einstein in order to capture the true physics near the origin of the universe."
Earlier work on the loop quantum cosmology in the group updated the concept of the Big Bang with the intriguing concept of a Big Bounce, allowing the possibility that our universe emerged from nothing but a super-compressed mass of matter.
When scientists use inflation paradigm along with Einstein's equations to model the evolution of the seed-like areas sprinkled throughout the cosmic background radiation, they find that irregularities serve as seeds that evolve over time.
Once the scientists used their new loop-quantum origins paradigm with its quantum-cosmology equations, they found that fundamental fluctuations in the very nature of space at the moment of the Big Bounce evolve to become the seed-like structures seen in the cosmic microwave background.
"Our new work shows that the initial conditions at the very beginning of the universe naturally lead to the large-scale structure of the universe that we observe today," Ashtekar said in his statement. "In human terms, it is like taking a snapshot of a baby right at birth and then being able to project from it an accurate profile of how that person will be at age 100."
Nelson said the paper pushes back the genesis of the cosmic structure of our universe from the inflationary epoch all the way to the Big Bounce.
"We now have narrowed down the initial conditions that could exist at the Big Bounce, plus we find that the evolution of those initial conditions agrees with observations of the cosmic background radiation," Nelson said.
Ashtekar said it is exciting that they may soon be testing different predictions from these two theories against future discoveries.
"Such experiments will help us to continue gaining a deeper understanding of the very, very early universe," he concluded.