Ultracold big bang experiment simulates early universe`s evolution
Scientists have been able to reproduce a pattern resembling the cosmic microwave background radiation, using ultracold cesium atoms in a vacuum chamber, in a laboratory simulation of the big bang.
Washington: Scientists have been able to reproduce a pattern resembling the cosmic microwave background radiation, using ultracold cesium atoms in a vacuum chamber, in a laboratory simulation of the big bang.
Lead author Chen-Lung Hung, PhD `11, now at the California Institute of Technology said that under certain conditions, a cloud of atoms chilled to a billionth of a degree above absolute zero (-459.67 degrees Fahrenheit) in a vacuum chamber displays phenomena similar to those that unfolded following the big bang.
He said that at this ultracold temperature, atoms get excited collectively. They act as if they are sound waves in air.
The dense package of matter and radiation that existed in the very early universe generated similar sound-wave excitations, as revealed by COBE, WMAP and the other experiments.
Hung said that inflation set out the initial conditions for the early universe to create similar sound waves in the cosmic fluid formed by matter and radiation.
The sudden expansion of the universe during its inflationary period created ripples in space-time in the echo of the big bang. One can think of the big bang, in oversimplified terms, as an explosion that generated sound, Chin said. The sound waves began interfering with each other, creating complicated patterns. "That`s the origin of complexity we see in the universe," he said.
These excitations are called Sakharov acoustic oscillations, named for Russian physicist Andrei Sakharov, who described the phenomenon in the 1960s. To produce Sakharov oscillations, Chin`s team chilled a flat, smooth cloud of 10,000 or so cesium atoms to a billionth of a degree above absolute zero, creating an exotic state of matter known as a two-dimensional atomic superfluid.
Then they initiated a quenching process that controlled the strength of the interaction between the atoms of the cloud. They found that by suddenly making the interactions weaker or stronger, they could generate Sakharov oscillations.
The universe simulated in Chin`s laboratory measured no more than 70 microns in diameter, approximately the diameter as a human hair. "It turns out the same kind of physics can happen on vastly different length scales," Chin explained. "That`s the power of physics."
The study has been published in journal Science.