Robert Dicke
Robert Henry Dicke (1916-1997) was one of the most accomplished American-born physicists ever, and one of the best experimental physicists in history. He made significant contributions to radar, atomic physics, cosmology, quantum optics, gravity physics, and astrophysics.
A tribute by his colleagues, Princeton Professors W. Happer, P. J. E. Peebles, and D. T. Wilkinson, summed up Professor Dicke's career as follows:[1]
- Bob held some 50 patents, from clothes dryers to lasers. He recognized that two mirrors make a more effective laser than the traditional closed cavity of microwave technology. In the company Princeton Applied Research he and his students packaged his advances in phase-sensitive detection in the now-ubiquitous "lock-in amplifier." With its successors this probably has contributed as much to experimental Ph.D. theses as any device of the last generation. Bob predicted and experimentally showed that collisions that restrict the long-range motions of radiating atoms in a gas can suppress Doppler broadening. The physics is the same as that of Mössbauer narrowing of gamma-ray lines; it is used in the atomic clocks of the Global Positioning System. He contributed to the concept of adaptive optics in astronomy. He was among the first to recognize that the accepted gravity theory, general relativity, could and should be subject to more thorough tests. His series of gravity experiments mark the beginning of the present rich network of tests. He set forth the idea of the anthropic principle that now plays a large part in speculation on what our universe was doing before it was expanding. Bob's visualization of an oscillating universe stimulated the discovery of the cosmic microwave background, the most direct evidence that our universe really did expand from a dense state. A key instrument in measurements of this fossil of the Big Bang is the microwave radiometer he invented.
Professor Dicke was a critic of the theory of general relativity as formulated by Albert Einstein. Instead, Dicke supported an alternative theory with Professor Carl Brans known as the Brans-Dicke theory, which includes a scalar field in addition to the tensor field definited by general relativity. At one point in 1970, after some testing of both theories, Dicke stated publicly that he stood by his theory against against Einstein's.[2] The differences between Brans-Dicke and general relativity are slight, and both explain currently observable data.
Dicke was closely related to the 1978 Nobel Prize for Physics. The 1978 physics prize went to Arno Penzias and Robert Wilson, who first measured the cosmic background radiation, though Dicke was the theorist who explained it, since Nobel prizes are given for discoveries.[3]
