Honoring Einstein and one man who proved him right
A Lexington man's contribution to Albert Einstein's theory of relativity was celebrated last week at the Westford observatory where the theory was put to the test 40 years ago.
About 100 invited guests at the Massachusetts Institute of Technology's Haystack Observatory in Westford listened as Dr. Irwin Shapiro discussed the fourth test of Einstein's general theory of relativity. Einstein published three of his famous articles in 1905, including the theory of relativity. The World Year of Physics is commemorating the centennial anniversary of Einstein's most accomplished year, along with remembering Shapiro's experiment.
''The World Year of Physics is an excellent opportunity to remember this historic fourth test," said Dr. Joseph Salah, director of the Haystack Observatory. ''Irwin Shapiro's experiment was groundbreaking in many ways, and represented a fundamental physics experiment that was the most important discovery made using the Haystack antenna."
Einstein had two theories of relativity, Shapiro said in an interview this week. One was the ''special" theory, which was published in 1905. The second was the ''general" theory from 1916, which is the one Shapiro tested in the 1960s.
Shapiro lives in Lexington and remains active in physics research. He is the director emeritus of the Harvard-Smithsonian Center for Astrophysics at Harvard University, a Timken University professor at Harvard, and is a senior scientist affiliated with the Smithsonian Institution.
The Haystack Observatory is an interdisciplinary research center, which deals with radio astronomy, geodesy, atmospheric sciences, and radar applications.
Shapiro came up with the idea for the experiment in 1962.
''In a way, it is kind of every physicist's dream to prove that Einstein was wrong," he said during his lecture. By proving Einstein right, Shapiro and his research team received national acclaim. The other researchers, who all worked at the time for the MIT Lincoln Laboratory in Lexington, were Gordon Pettengill, Michael Ash, Melvin Stone, William Smith, Dick Ingalls, and Rich Brockelman.
Einstein's theory said that the speed of a light wave depended on the strength of the gravitational force along its path. Shapiro and his team proposed measuring the time delays between the transmission of radar pulses through the sun's gravitational field toward Venus or Mercury and then measuring the time it took the echoes to return to Earth. At the time, however, there existed no radar capable of bouncing a signal off an object as far away as Mercury or Venus when they are behind the sun.
That changed in 1964, when MIT unveiled its 120-foot Haystack antenna in Westford, deemed the world's most sensitive antenna at the time. Shapiro and his research team, which conducted their test at the observatory from November 1966 to August 1967, were able to confirm that the radio waves slowed down when they went through the gravitational field on the sun.
At Shapiro's appearance last week, ''People were invited from Harvard University, Lincoln Laboratory, teachers from area high schools, undergraduates from schools like Harvard and Brandeis," said Madeleine Needles, primary coordinator for the Haystack's Research Excellence for Teachers program.
Shapiro spoke for an hour and a half about events leading up to his historic experiment and what happened thereafter.
''In order to do the experiment, we needed a more powerful radar transmitter," he said in the interview. ''The director of Lincoln Laboratory called the Air Force and got $500,000 for funding simply over the phone. He called it a Christmas present," Shapiro added with a laugh.
While it would have been nice to prove Einstein wrong, Shapiro said, he is proud of his experiments, and amazed by Einstein's brilliance.
''Nature behaves exactly as Einstein predicted," he said. ''All the experiments done so far have agreed with the predictions from Einstein's theory." 