On December 3, astrophysicist David Spergel was honored with the 2018 Breakthrough Prize in fundamental physics for his work mapping the early universe. He shares the award with Charles Bennett of Johns Hopkins University, Gary Hinshaw of the University of British Columbia, and Norman Jarosik and Lyman Page of Princeton University. Page is currently on sabbatical at the Flatiron Institute in New York City.
Spergel serves as director of the Center for Computational Astrophysics at the Flatiron Institute. He is also the Charles A. Young Professor of Astronomy at Princeton University.
The prize recognizes the researchers’ pioneering work on NASA’s Wilkinson Microwave Anisotropy Probe (WMAP). Data from the probe “improved our knowledge of the evolution of the cosmos and the fluctuations that seeded the formation of galaxies,” according to the Fundamental Physics Prize Foundation, which established the award in 2012. The researchers will each receive a trophy and share a $3 million prize.
The WMAP satellite, launched in June 2001, took detailed images of the cosmic microwave background, the radiation left over from the primordial fireball that gave birth to our universe about 13.8 billion years ago. This radiation, the oldest light in the cosmos, represents a time when the universe was just 380,000 years old.
The temperature of this afterglow of the Big Bang varies only slightly across the sky, by millionths of a degree from an average of 2.7 kelvins. WMAP detected these differences and matched them against cosmological models. The first results from WMAP, announced in 2003, offered an unprecedented ‘baby picture’ of the universe.
The measurements supported a so-called flat universe dominated by dark energy, a mysterious repulsive force pushing the universe apart (not to be confused with dark matter, which exerts a gravitational pull). The data also provided support for the theory of cosmic inflation, a hypothesized exponential expansion of space-time immediately following the Big Bang. “The precise measurements led to the establishment of the standard model of cosmology,” Spergel explains.
He recalls the intense effort in December 2002 as the team prepared the first WMAP results for publication. He dropped his family off at his parents’ home after Christmas so he could work long hours with his colleagues to analyze the data. “For the team, I bought T-shirts that read ‘sleep is for the weak,’” he says.
The late astrophysicist John Bahcall called the 2003 WMAP announcement “a rite of passage for cosmology from speculation to precision science.” Bahcall, who worked at the Institute for Advanced Study in Princeton, New Jersey, said astronomers everywhere would remember the moment they heard the first results from WMAP.
The probe continued to examine the sky during the next decade, and the WMAP team released its final dataset in 2012. It revealed a universe comprising roughly 71.4 percent dark energy, 24 percent dark matter and 4.6 percent ordinary matter, and it dated the first stars to about 400 million years after the Big Bang. The data also put limits on a value called the tensor-to-scalar ratio, which defines the level to which primordial gravitational waves polarize the light of the cosmic microwave background. A detection of primordial gravitational waves would help to explain why and how inflation occurred.
The WMAP probe was the successor to the Cosmic Background Explorer (COBE), whose project scientists won the 2006 physics Nobel, and was followed by the Planck space observatory. Even with all the data collected by these probes, “there’s still a lot we don’t know about the universe, such as the nature of dark energy,” Spergel says.
Spergel and Page are currently part of the Simons Observatory project, which will look for polarization patterns in the cosmic microwave background. Along with insights into inflation, the observations could provide clues to the nature of dark matter and dark energy.