Professor Charles L. Bennett of the astrophysics department recently won the 2010 Shaw Prize in Astronomy, which comes with $1 million dollars in cash, for his groundbreaking contribution to the measurement of the age and content of the universe. He was able to do so in his capacity as Principal Investigator of NASA’s highly successful Wilkinson Microwave Anisotropy Probe (WMAP), an observational satellite that his team of scientists built.
Prior to embarking on the WMAP experiment, Bennett was a Senior Scientist for Experimental Cosmology, Goddard Senior Fellow and Infrared Astrophysics Branch Head at the NASA Goddard Space Flight Center. Bennett was at the Carnegie Institution of Washington’s Department of Terrestrial Magnetism during the summers from 1976 to 1978.
He sat down with The News-Letter recently to discuss his recent achievements that merited him the Shaw Prize.
The News-Letter (N-L): What is the Shaw Prize?
Charles Bennett (CB): First, a clarification. I shared the Shaw Prize with my colleagues Lyman Page and David Spergel, who both worked on the WMAP experiment.
But in any case, the Shaw prize was started by Run Run Shaw, who started a foundation after his name. The Shaw foundation does philanthropic work, especially focusing on educational work. They decided to start the Shaw prize, which is awarded in three areas: in astronomy, which of course was the one relevant to me, in math, and in [life science]. They wanted it to be Nobel prize-like, hence the million dollars. Indeed it’s informally referred to as the Nobel Prize of the east. And so obviously it’s a big honor to get it.
We flew to Hong Kong to receive the prize. We did interviews with reporters from China and Hong Kong. The whole afternoon [was] dedicated to these interviews. There’s also a requirement to give a lecture at one of the Universities in Hong Kong. They chose for me to give a lecture at the University of Hong Kong, which I was happy to do. [At my lecture in Hong Kong] there were high school students and college students, as it was meant to be an approachable lecture.
After that, we had a very formal ceremony in the convention center there with lots of media. It was a very pleasant ceremony.
N-L: What did you win the Shaw Prize for?
CB: I was awarded for the work I did on WMAP Satellite. Way back in 1995, I submitted a proposal to NASA with a team of scientists to build this particular space mission and to use it to make fundamental measurements about the nature of the universe. Fortunately, that proposal was accepted in 1996, and I’ve got the framed acceptance over there [in my office], and we launched that satellite in 2001. The other letter next to the acceptance letter is the clear-to-launch letter. They’re the symbolic bookends to the WMAP project.
We released our big first major results [from WMAP] in 2003. And since then we’ve been putting out additional results, and all those results are what I suppose are being recognized by the Shaw Prize.
N-L: What were those results?
CB: The result that is probably the best known to the public is [our measurement of] the age of the universe, which is 13.75 billion years. When I went to school as a graduate student we didn’t know if it was nine billion years or 20 billion years; now we know it’s 13.75 billion years old. That actually made the Guinness Book of World Records as the most accurate determination of the age of the universe.
But we found far more than that of great importance. One thing the satellite did is it took a census of what is out there, such as the various forms of mass and energy in the universe. The result of that was that only 4.5 percent of the mass and energy in the universe is in atoms. By atoms I mean the elements of the periodic table, one of the things that you’re probably familiar with from chemistry class. [Atoms are] what we’re made up of, what the buildings at Hopkins are made up of, what the world is made up of, and all those things constitute only 4.5 percent of the universe. Which is not much.
About 23 percent or so [of the mass and energy of the universe] is made of something that we call Cold Dark Matter, which is different from atoms. In fact, atoms are a kind of material that we consider interactive with light. But Cold Dark Matter doesn’t interact with light at all. If it’s sitting out there, it’s not sending any light toward us like a star does, which is why it’s dark. It also does not block light behind it, does not scatter light; it just doesn’t have anything to do with light, which makes it very difficult to find.
The only way to find it is to use the fact that it does have gravity, because it is, in the end, matter. Matter has gravity, so we can see it’s gravitational effects. There’ve been a number of different experiments, besides the WMAP one, that have detected the gravitational effects that tell us that most of the matter in the universe isn’t atoms, but Cold Dark Matter. The word cold means that it’s not moving very fast, that in fact, it’s not time-relativistic. So we don’t know what this particle we call dark matter is, but we might learn more from the Large Hadron Collider in Switzerland. One thing, however, is for sure: it’s the predominant form of matter in the universe.
Of course if you add up the amount of atoms and the amount of Cold Dark Matter, you’ll find that we’re still missing most of the mass and energy of the universe. The lion’s share, which is maybe 73 percent to 75 percent, is something we call dark energy. We do not have too much of an idea of what that is actually.
But our satellite, the WMAP, confirmed not only that it exists but that it’s about 73 percent of the mass and energy of the universe. Indeed, it’s the predominant form of mass and energy in the universe.
Of course, we still don’t know much about what it is. One possible explanation is that it corresponds to the energy of the vacuum, of empty space. It’s sometimes said, ‘How much does nothing weigh?’ In some ways that’s the simplest explanation. There was actually a preexisting problem on that. You could’ve asked the physicists in this building, ‘How much does nothing weigh? Tell me from your laws of physics.’ And so the first thing they calculated is that it’s enormous; way bigger than we know it would be. We instantly knew that answer was wrong. So the next best answer was there must be something in the laws of physics that make it exactly zero, because it’d be weird if it canceled by tenth to the hundred, and then missed by a little bit. Then they predicted the answer would be zero, although they don’t really have a theory that tells them why.
And now you go and find that there actually is something that cancels out: dark energy. If it is the vacuum, then it relates to a historic problem that preexisted in physics.
In sum, the WMAP took a census of the universe and found that the atoms, cold dark matter and dark energy are the major constituents of what’s out there.
N-L: Is that the focus of your studies?
CB: I got my Ph.D. at MIT and when I was finishing up like all good graduate students, I started asking myself what I [was] going to do with my life. I heard a talk at MIT by one of the professors about a space mission called COBE (COsmic Background Explorer) and this sounded completely fascinating to me. It attracted my attention right away. I actually asked this professor at MIT whether there was any possibility for me to get a job working on this mission and he said that there was. I ended going to work at the NASA Goddard Space Flight Center to work on COBE. It actually made major discoveries, including two Nobel Prizes. That was sort of ten-ish years of my life after getting my Ph.D. It was very rewarding to produce major results.
As soon as we got those results, which included detection for the first time of temperature changes across the sky, it was obvious that I should follow up on that and measure that with more sensitivity and focus to get all these kinds of things like the age and content of the universe. So that’s why I put in a proposal for WMAP.
My career has been working on COBE and then working on WMAP and recently in the last year I’ve been starting up on a new experiment. Everything in my career has been in space, but my latest experiment is actually ground-based. My students across the hall [from my office] in the lab are working on it, which would be constructed in Chile.
But all of these have in common studies of what we call the cosmic microwave background. My whole career’s been about that. It has been an immensely valuable signal that’s coming to us . . . there’s one key prediction of the Big Bang Theory that hasn’t been measured, and that’s what this new experiment is about, trying to get there to measure that.
N-L: What got you interested in astrophysics in the first place?
CB: When I was in middle school, I had a hobby of electronics. I would take things apart. I would build little things up. I actually worked at a radio and TV repair shop back then. I was a ham radio operator, and I built some of my own equipment. This was my hobby. School was okay, but I loved doing this.
For one of my birthdays my grandmother bought me a telescope, which I would take out to the backyard and use to look up at the sky.
That became a hobby too. I read that there was a career called radio astronomy, where people would look up at the sky for the radio waves coming, and I thought that it married my two hobbies together. I couldn’t think of anything more fun to do. So I decided way then to become a radio astronomer. And I still love what I’m doing.
N-L: What’s next?
CB: This next project is called CLASS (Cosmology Large Angular Scale Surveyor). It’s a microwave instrument that we hope to build in Chile that will be used to look for this particular signals from the beginning of the universe.
N-L: Who’s your favorite physicist?
CB: Albert Einstein. But I will say that I’m wary of blindly worshipping an idol. Everyone makes mistakes, including Einstein. That’s also the fun of it. You find mistakes, you fix them. That’s interesting.
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