Physics Professor Helps Develop New Instrument for Seeing the Early Universe

Dr. Ted Bunn, professor of physics, worked with an international collaboration of physicists and astronomers that has just finished construction of a new instrument that will help them measure radiation that is left over from the early universe, just after the big bang. The instrument was recently moved to its observing location at a radio telescope in the mountains of Argentina, where it is undergoing final testing and commissioning. 

Bunn explains that some 13 billion years ago, or roughly 380,000 years after the big bang, the expanding universe had just cooled enough to condense from hot, thick plasma into atoms and neutral particles that allowed light to pass through it. Some of the light that was already “en route” at that time is still arriving at the Earth today, and is known as the “cosmic microwave background radiation.” Capturing this radiation gives astronomers a glimpse of what the cosmos looked like way back then — “the universe’s baby pictures,” quips Bunn. 

The QUBIC group, short for “Q & U Bolometric Interferometer for Cosmology,” began in 2008 and has grown to include over 100 researchers from 20 universities in Argentina, Italy, France, the U.K., and the U.S. Bunn himself was an early member of the collaboration, and he played a unique role in the project. While many members of the group were observational astronomers specializing in data analysis, instrument building, or electronics, Bunn was simply really good at solving very complex math problems. (He describes himself as the group’s “pet theorist.”) Bunn’s work was crucial in the very early stages of the project’s development, as he worked out how to optimize an array of antennas to collect the maximum possible amount of useful data, a key step in setting the project on a path toward success. Bunn incorporated UR undergraduate students in his research throughout his participation in the project.

The collaboration’s new instrument, a millimeter-wavelength interferometer, is designed to measure very tiny variations in the polarization of the cosmic microwave background radiation. Patterns in these tiny variations may give scientists clues that will help them understand how the universe expanded during the very first fraction of a second. The instrument’s completion marks an important milestone, and will be of significant importance to many astrophysicists over the years to come. Bunn is happy when he reflects on his contribution. “It’s exciting to be playing a part in measurements that have the potential to enhance our understanding of the universe.”