Hopkins professor honored for shedding new light on the universe
Charles Bennett explains research that revealed 14-billion-year-old history
Charles Bennett (Courtesy of Will Kirk, Baltimore Sun / June 29, 2012)
Last month, Bennett and the team of researchers he led for more than a decade received the Gruber Foundation's annual cosmology prize, recognizing the body of work they contributed to the field. Their discoveries of the universe's makeup and how it has changed over time formed the foundation of what has become known as the standard model of cosmology.
But with any scientific discovery come more questions to be answered, Bennett said in an interview.
Can you explain the basics of the standard model you helped develop?
In an idea sense, it's that the universe is composed of atoms, but it's less than 5 percent of the universe. There's this stuff called dark matter, which is not at all like atoms — we don't even know what it is — and then we have this strange thing that we call dark energy. You start to get the feeling that anything called "dark" means we don't understand it, and there's some truth to that.
When we say standard model, we say we know about the dynamics of the universe, its thermal history and its components, all of this in one package. And we know these things now with a high degree of not just confidence, but with highly accurate numbers.
You came to these conclusions studying data on radiation floating in space. How do you learn from that data?
Radiation is basically light. There's light you can see with your eyes, and if you go beyond what your eyes can see, there's ultraviolet light, X-rays and gamma rays, or infrared light down to radio and microwaves. In the early universe, it was very dense and very hot in the beginning, there were nuclear reactions going on, and it was fusing hydrogen atoms together from hydrogen to helium.
The reactions stop, but the radiation is still there. It has been traveling through space ever since. We are looking at light that's coming from so far away in the universe it's taken 13.7 billion years to get to us, but it is the light.
In effect, we have a time machine. In a sense, it's like a fossil. That's what we've made a picture of, and that's why it carries so many clues of what happened early on.
You measured the data using NASA's Wilkinson Microwave Anisotropy Probe, or WMAP. What kind of technology did it use?
WMAP was a competed mission. NASA put out a call for people's ideas for what kind of space mission would be worth doing. If memory serves, there were 65 proposals, mine included. That was in 1985. This was a turning point for NASA, looking for smaller and cheaper missions to do, and one of the consequences was you had to use technology that already existed.
At the end of the day when we were selected April 12, 1996, we turned to Marian Pospieszalski and the National Radio Astronomy Observatory. It's called a microwave amplifier. This kind of light is coming from us at all times and we need to collect it and amplify the signal.
What are some discoveries that have been made based on the foundation of your research?
Pretty much any good scientific research that makes progress raises new questions. It's the nature of science. One is that the "Big Bang" theory is not about a big bang, it's about the heating and cooling of the universe. One big question that is still unanswered is, what happened at the beginning?
Our best theory right now is what we call inflation. The idea is the universe started with random fluctuation and this region of space that fluctuated expanded in size rapidly in a matter of seconds.
Is that your next research foray?
I'm pushing very hard in that direction. My group here at Johns Hopkins and others are working on a new instrument called CLASS, the Cosmology Large Angular Scale Surveyor. We're going to survey large angular scales of the sky with as microwave receiver, this time not in space but on the ground in the Atacama Desert in Chile.
Education: B.S. in physics and astronomy, University of Maryland College Park, 1978; Ph.D. in physics, Massachusetts Institute of Technology, 1984
Positions: Astrophysicist, NASA Goddard Space Flight Center, 1984-2004; head, Goddard infrared astrophysics branch, 1994-2000; professor of physics and astronomy, Johns Hopkins University, 2005 to present.
Awards: 2005 Henry Draper Medal; 2006 Gruber Foundation Cosmology Prize as a team member for research using NASA's Cosmic Background Explorer; 2006 Harvey Prize; 2009 Comstock Prize in Physics; 2010 Shaw Prize in Astronomy; 2012 Gruber Cosmology Prize