Vietnamese-American physicist Nguyen Trong Hien was born in 1963 in Da Nang city. He is now working as the astronomy supervisor for the Jet Propulsion Laboratory (JPL) at NASA (National Aeronautics and Space Administration) in the United States. Recently, he and his team announced the discovery of the gravitational wave, proving the theory of expansion of the universe. He received his PhD at Princeton University in 1993. He talks to Hong Nhung about his work and latest projects.
Inner Sanctum: The BICEP2 (Background Imaging of Cosmic Extragalactic Polarisation) project was launched before a long time, attracting scientists from many institutes and agencies across the US. Can you explain clearly about the role of each agency and scientist in developing this project?
I had submitted BICEP2 to the NASA's JPL in May 2006. At that time, the scientific team who were working on this project were I (the team leader), Jamie Bock, Darren Dowell and Chao-lin Kou, the youngest member, currently associate professor in Stanford University.
BICEP2 is the second generation of microwave's radiation test chain, led by Caltech faculty. BICEP, or BICEP1 as we named it, is the first generation of the test chain. Bock is the person who gave the idea and is also the instructor of NTD bolometer in JPL. At that time, Bock and I were working together to test the induction system for the Herchel and Planck space observatory built by Bock.
Bock, at that time our team member at JPL, and professor at Caltech, was the leader of BICEP2 test alongside professor Andrew Lange. Bock is perhaps one of the most outstanding leaders of our generation whom I ever had an opportunity to work with.
As we already held in our hands the most advanced technology of our time, we decided to use it for seeking the existence of gravitational wave. Another reason is that we were ahead of other research teams by three to five years, and the advantage was on our hands. And, we also had Kou and John Kovac, who endured the long winter with me in Antarctica in 1994.
Kovac had just completed his PhD thesis in Chicago and was doing a research with Lange at Caltech. He is one of the most hard-working and intelligent persons I have ever met. Both Kovac and Kou played an important role in developing BICEP2. Kovac raised the idea and created BICEP2 to replace BICEP1. But Kou was the person who designed the TES system to BICEP2 later on. We then included Clem Pryke, a professor of Minnesota University, to undertake data analysis.
After the study period, Kou was appointed as associate professor at Stanford, and so was Kovac at Harvard. Therefore, Stanford, Harvard and Minnesota became the major members of BICEP2 with Caltech. We were also provided with electric and heat components by other institutes across the country.
Inner Sanctum: The domestic physicist circle is feeling proud as your name, a Vietnamese scientist, is in the list of members of the project. Can you tell us more about your contribution to this work?
As the principal investigator, the presider of BICEP2 at JPL, I take responsibility of two things: producing the devices, electric and heat organs, and instructing the TES superconducting system.
BICEP1 uses NTD bolometer, with 50 sensor units. BICEP2 uses TES bolometer, with 512 units. Both the systems are considered the "state-of-the-art" in the field of physics and astronomy. Planck, the European space observatory to observe background radiation, also uses NTD bolometer provided by JPL. TES is the latest conduction product designed by our team. Because of TES, the duration of our project was shorter. Three years of BICEP2 is equal to 30 years of BICEP1.
Inner Sanctum: Can you share with us the unforgettable moments you had spent with your team?
BICEP2 was approved at the end of September 2006. We swiftly deployed the BICEP2 manufacture in October 2007. At that time, BICEP had just been brought to Antarctic. As we foresaw that BICEP1 will not be sensitive enough to discover gravitational wave, we calculated the development of BICEP2 while using BICEP1 as the navigator.
In the beginning of 2006, I came to Antarctic again to observe the first BICEP experiment. The trip also involved professor Andrew Lange, the supreme leader of BICEP, BICEP2 and Keck. We usually had dinner with our students and interns in the astronomic station.
Lange, together with his student Bock, previously successfully had set up the balloon observations of millimetric extragalactic radiation and geophysics, called Boomerang. It was a resounding success as the experiment provided the proof of the flatness of space, followed by Lange's nomination for Nobel Prize.
Lange is no longer with us. He took his life in the beginning of 2010, a few days after BICEP2 had just been brought to operation in Antarctica. We had always seen him as the soul of BICEP2. Our study was dedicated to him: "We dedicate this paper to the memory of Andrew Lange, whom we sorely miss."
Inner Sanctum: What is your next plan for BICEP2 and the research group?
We need to testify the result. This is similar to when we want to know the result of the election. First, we turn on CNN and then BBC. If the result is the same, then the news is reliable. Right now, we have finished the 150-GHz frequency band. Next, it will be a 100-GHz observatory. Soon, the world will hear the final verdict at the end of this year or the beginning of next year. — VNS