What happened in the first trillionth of a trillionth of a trillionth of a second after the Big Bang? Super-sensitive microwave detectors, built at the National Institute of Standards and Technology (NIST), may soon help scientists find out. The new sensors, described on Saturday at a meeting of the American Physical Society (APS) in Denver,* were made for a potentially ground-breaking experiment scheduled for a year from now to make new measurements of the cosmic microwave background (CMB)—the faint afterglow of the Big Bang that still fills the universe.
The experiment, a collaboration of NIST, Princeton University, the University of Colorado at Boulder, and the University of Chicago, will take place in the Chilean desert. A large array of powerful NIST sensors on a telescope will look for subtle fingerprints in the CMB from primordial gravitational waves—ripples in the fabric of space-time from the violent birth of the universe more than 13 billion years ago. Such waves are believed to have left a faint but unique imprint on the direction of the CMB's electric field, called the "B-mode polarization." These waves—never before confirmed through measurements—are potentially detectable today, if sensitive enough equipment is used.
"This is one of the great measurement challenges facing the scientific community over the next 20 years, and one of the most exciting ones as well," says Kent Irwin, the NIST physicist leading the project.
If found, these waves would be the clearest evidence yet in support of the "inflation theory," which suggests that all of the currently observable universe expanded rapidly from a subatomic volume, leaving in its wake the telltale cosmic background of gravitational waves.
The experiment depends on new NIST microwave detectors that are designed to measure not only the intensity but also the polarization of the microwave background. The B-mode polarization signals may be more than a million times fainter than the temperature signals. To detect such subtle patterns, the NIST detectors will collect significant amounts of radiation efficiently and will be free of moving parts and traditional sources of systematic error, such as vibration and magnetic interference. The NIST team previously built superconducting amplifiers and cameras for CMB experiments at the South Pole, in balloon-borne observatories, and on the Atacama Plateau in Chile.
For additional details, images and animation, see "NIST Super-Sensors to Measure 'Signature' of Inflationary Universe."