Suzanne Staggs, the Henry DeWolf Smyth Professor of Physics, has spent much of her professional life studying and making measurements of the cosmic microwave background (CMB), the glowing radiation left over from the big bang.
According to cosmologists, the big bang describes the onset of the expansion of the very fabric of the universe’s space-time, which commenced about 13 billion years ago. The CMB is therefore the oldest light in the universe, and carries with it clues to how the universe was created and how it continues to expand.
The discovery of CMB occurred in 1965, the year Staggs was born. The discovery was accidental and informed by Princeton researchers. Two Bell Laboratory scientists, Arno Penzias and Robert Wilson, were conducting experiments on low levels of microwave radiation when they became aware of a persistent background noise in the sensitive antenna they were using. Puzzled by the noise, they turned to four Princeton astrophysicists — Robert Dicke, Jim Peebles, David Wilkinson and Peter Roll — who at that moment were preparing calculations and an experiment to prove the existence of radiation left over from the big bang. They shared their research with Penzias and Wilson and, in a generous act of collaboration, published back-to-back papers describing the noise and attributing it to CMB. Penzias and Wilson later won a Nobel Prize for the discovery.
Years later, when Staggs came to Princeton as a graduate student, she was hoping she could return to Los Alamos, where she had done undergraduate research on neutrinos with a notable research team there. Neutrinos are the subatomic particles produced in nuclear decays and high-energy collisions. Wilkinson, who was then chair of the physics department, had other plans for her.
“He said Princeton is great, and you truly do not want to leave this place with all its connections,” Staggs recalls. She agreed to work on his research team, and Wilkinson, someone she describes as “a real hero in the field,” was suddenly her thesis adviser.
“He was an amazing mentor,” she says of Wilkinson, who died in 2002. Collaborating with Wilkinson, she worked to complement CMB data precisely measured and mapped by the NASA satellite COBE, which was launched in 1989 with the help of Wilkinson. The next generation CMB satellite was named after Wilkinson: the Wilkinson Microwave Anisotropy Probe or WMAP.
“COBE made these great measurements, but there was a range of frequencies they couldn’t get to, so Dave wanted to make some more measurements at those unsurveyed frequencies,” Staggs says. “That’s what I worked on. It was a niche field then.”
Today, Staggs is playing another significant role in the advancement of cosmological knowledge. She is the project lead on a large grant to build an upgraded camera for a six meter telescope constructed in 2007 in the Atacama Desert in Chile. The National Science Foundation-supported instrument is designed to make high-resolution observations of the sky to study CMB with precision previously unimagined.
Among other things, Staggs says the new data may help cosmologists better understand dark energy, a hypothetical form of energy that permeates all space, and may also improve our knowledge about the nature of neutrinos, those same particles Staggs abandoned in favor of the CMB once she came to Princeton.
“Right now, we know the universe is expanding, and what’s exciting is that we know that the expansion rate is increasing,” she says. “Why is this happening? Dark energy is something that can cause that.”
For Princeton students interested in studying such lofty topics, Staggs says the possibilities are endless, in part because of Princeton’s early and continuing role in major cosmological discoveries.
“How strange that many people who thought up these amazing ideas are in the Princeton area,” she says. “We have people who are building the instruments and producing the data in the context of theoretical ideas. And then we have other people in the area who have theoretical suggestions to explain what’s going on.”
Princeton students, she says, have access to the knowledge and the equipment, and she believes many of them are up to the challenge of helping unearth nature’s most profound secrets and working in this exciting and demanding field.