Robert H. Dicke
Robert Henry thickness ( born May 6, 1916 in St. Louis, Missouri, † March 4, 1997 in Princeton ) was an American physicist and astrophysicist.
Life and work
Thickness was the son of a patent examiner and patent attorney. He studied at Princeton University (Bachelor 1939) and received his doctorate in 1941 at the University of Rochester in Nuclear Physics. After that, he was from 1941 to 1946 at the Radiation Laboratory of the Massachusetts Institute of Technology (MIT ) ( where he followed his teacher Lee DuBridge ), where he worked on radar technologies (including a microwave detector, the thickness Radiometer). From 1946, he was first an assistant professor and since 1957, Cyrus Fogg Brackett Professor of Physics at Princeton University. In 1975, he was there, Albert Einstein Professor of Science. In 1984 he retired. 1967 to 1970 he was in Princeton Board of physics faculty. In 1954/55 he was a visiting professor at Harvard.
Robert H. Dicke concluded in 1964 ( with James Peebles and others) that the assumption of a Big Bang, a cosmic residual radiation ( cosmic microwave background ) still have to be present today, which would correspond to the radiation of a black body of temperature of about 3 degrees Kelvin. This had been suspected in the 1940s, George Gamow, Ralph Alpher and Robert Herman, their prediction was but forgotten. Thickness was experimentally embark on the quest for it also, but others came to him before. 1965 was such radiation detected by Arno Penzias and Robert W. Wilson in Holmdel / New Jersey ( by chance when checking the sensitivity of their antenna) that comes to us and evenly from all directions, so no cosmic object could be assigned.
Thickness developed a circuit for fast switching a receiver input between an antenna and a reference resistor. This arrangement, named after its inventor thickness switch that allows reference measurements for the elimination of noise sources in receiving circuits. Thickness is also considered the inventor of the lock-in amplifier, which he marketed in his company Princeton Applied Research. In the 1940s he was a leader in the development of a modern analysis of microwave electronics by means of symmetry relations and scattering matrices Reziprozitätsrelationen. Thickness held about 50 patents. From him also early ideas come to adaptive optics and he also played a role in the development phase of the maser and laser, with a patent of 1956 and proposals in an influential work of 1954. He suggested therein methods for transition of the maser from the microwave range ( as originally developed by Charles Townes ) in the infrared region by using a Fabry -Perot interferometer ( that is, two parallel mirrors as the optical resonator) before. Next he developed in his work of 1954, a simple model (thickness model ) for the generation of coherent radiation ( called by him Superradiant ) in a Maser ( N two-state atoms in a cavity interacting with the radiation in the dipole approximation ).
Thickness developed with Carl H. Brans one named after them scalar - tensor theory of gravitation ( Brans Dicke theory ) as an alternative to Einstein's General Relativity (GR ). Motivation were also the cosmological ideas of Paul Dirac (Large Number Hypothesis ) and Mach's principle. The theory violates the equivalence principle, the thickness in a row with P. Roll and R. Krotkov tested in the context of his theory of gravitation, he also articulated early on a weak form of the anthropic principle. Thickness was also active in other questions of the test of general relativity, for example, in the measurement of the flattening of the sun, which can contribute to the perihelion advance of Mercury, one of the classical tests of GR. He also tested the equivalence principle on distance measurements to the moon ..
With the thickness -fix principle he succeeded in 1960, the improvement of a method for suppression of short interfering signals in radars.
In the 1980s, he dealt among other things with helioseismology.
Spectroscopy in describing the thickness constriction ( narrowing thickness ) of line widths, if the mean free path is much shorter than the emitted wavelength. The effect is used in atomic clocks, for example, the Global Positioning System enabled and then more precise measurements in atomic physics.
1963 to 1966 he was standing in front of the Physics Committee of NASA, where he served until 1970. Since 1967 he was a member of the National Academy of Sciences.
He was married since 1942 to the British Annie Currie, with whom he had a daughter and two sons.
Writings
- Gravitation and the Universe. In: American Philosophical Society. In 1970.
- With Peebles: The big bang cosmology - enigmas and nostrums. In: Israel Hawking: General relativity, Einstein centenary survey on. Cambridge University Press, 1979.
- With Carol Gray Montgomery, Edward Mills Purcell: Principles of Microwave Circuits. Office of Scientific and Research Development, National Defense Research Committee, McGraw Hill 1948, Dover 1965.
- With James P. Wittke: Introduction to Quantum Mechanics. Addison-Wesley 1960.
- The theoretical Significance of experimental relativity. Gordon and Breach 1964.