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Howard Percy Robertson, who was elected a Fellow of the Royal Astronomical Society in 1944, died in Pasadena, California, on 1961 August 26, as a consequence of a pulmonary embolism brought on by injuries sustained in a traffic accident. His death brought to an end a distinguished career in science, particularly in differential geometry, relativity and cosmology, as well as in the application of science to military strategy and international political relations. At his death he held the position of Professor of Mathematical Physics at the California Institute of Technology and was Foreign Secretary of the National Academy of Sciences of the United States.
Professor Robertson was born in Hoquiam in the State of Washington on 1903 January 27, the son of George Duncan and Anna McLeod Robertson. In 1923 he was married to Angela Turinsky. Two children were born to them: a son, George Duncan, and a daughter, Mariette. His wife and children survive him. Robertson received his bachelor's and master's degrees from the University of Washington in 1922 and 1923 and his doctor's degree from the California Institute of Technology in 1925 at the age of 22. He then studied as a National Research Fellow in Göttingen and Munich. From 1927 to 1929 he served as Assistant Professor of Mathematics at the California Institute of Technology. In 1929 he went to Princeton as Assistant Professor of Mathematical Physics and, after rising to a full professorship there in 1938, he returned to the California Institute as Professor of Mathematical Physics in 1947.
Robertson had exceptional mathematical powers coupled with a deep insight into physical processes. Early in his career he gave the solution of Einstein's cosmological equations for the case of a homogeneous and isotropic universe. This solution is incorporated in the "line element" which bears his name. In all of his papers, Robertson emphasized that this solution was independently discovered by A. J. Walker. It has served as the basis of many of the numerous papers which have subsequently been written on relativistic cosmology. In addition Robertson succeeded in obtaining a general solution for two-body problems in general relativity.
The discovery of the red shift-distance relation and of the expanding universe by Edwin Hubble opened a continuing field of theoretical investigations for Robertson. From the beginning he was closely associated with Hubble, Milton Humason and Richard Tolman, and this association extended in later years to the younger staff members of the Mount Wilson and Mount Palomar Observatories who continued the red shift measurements. Robertson undertook to express the consequences of the general theory of relativity in regard to the red shift-distance observations in the most precise and explicit form possible. The greatest difficulty in the interpretation of these observations lies in the fact that distance is measured indirectly through measurements on the apparent luminosity or magnitude of the brightest stars in galaxies or of the brightest galaxies in clusters of galaxies. First of all Robertson succeeded in establishing the correction for the effect of the red shift on apparent luminosity by proving quite generally that this latter quantity is proportional to the absolute luminosity divided by the square of the Doppler shift. He ultimately succeeded in establishing the second-order terms in the red shift-magnitude relations which take into account the acceleration or deceleration of the universal expansion as well as the evolutionary history of stellar or galactic systems. He pointed out that the various expanding cosmologies all agree, except in physical interpretation, on the mathematical nature of the first-order Hubble relation but that differing cosmologies gave differing theoretical values for the acceleration parameter in the second-order term. Thus Robertson pointed the way to the critical observational test of relativistic cosmologies and made clear the necessity for great care in correcting for evolutionary effects. These tests were begun in Robertson's lifetime using the 200-inch Hale telescope but they were by no means completed. Their completion in the decades to come will mark the final culmination of his contribution to science. Robertson, himself, remained aloof in the controversies between the advocates of the various theoretical cosmologies. He preferred to have laid the basis within the framework of general relativity on which these cosmologies could be put to the observational test. His point of view was expressed beautifully in the last lines of his article in the Astrophysical Journal for May, 1936: "In fine, we are inclined to believe that our investigations may in some measure strengthen, on purely formal grounds, the claims of the general theory of relativity; in any event, we maintain that it cannot be rejected on such grounds, and are the more content to rest the case with the empirical."
Recognition of Robertson's achievements as a scientist came with election to the National Academy of Sciences of the United States in 1951. In 1958 he was elected Foreign Secretary of the Academy. In addition to being a Fellow of the Royal Astronomical Society he was also a Fellow of the American Physical Society and a member of the American Mathematical Society, the American Philosophical Society, the American Astronomical Society, the Edinburgh Mathematical Society, Sigma Xi and Phi Beta Kappa.
An outstanding phase of Robertson's career was the way in which, during World War II and after, he turned from abstruse theoretical subjects to the practical problems of military strategy. His scientific interest turned to applied problems in elasticity, hydrodynamics and shock wave propagation. He won the respect of both scientists and military officers in his grasp of war problems, his keen analytical ability and his skill in bringing the results of scientific analysis into useful and understandable form. He served as scientific liaison officer to the London Mission of the Office of Scientific Research and Development from 1943 to 1946. From 1944 to 1947 he was an expert consultant to the office of the American Secretary of War. In 1946, he was awarded the Presidential Medal for Merit.
In the years after World War II Robertson continued to be heavily engaged in military advisory tasks. He spent two years as scientific adviser to the Supreme Commander of the Allied Forces in Europe. He spent an additional two years as Scientific Director of the Weapons System Evaluation Group in Washington, working directly with the Joint Chiefs of Staff. He served on numerous science advisory boards including the Defense Science Board as chairman, the President's Science Advisory Committee, the Science Advisory Group to NATO and others. His activities along these lines were not confined to government service. He was a trustee of the Systems Development Corporation, the Institute for Defense Analysis, and the Carnegie Endowment for International Peace and was a director of the Northrop Aviation Corporation.
In spite of his many outside activities, Robertson played his full part as a faculty member of the California Institute of Technology. He scheduled his lectures ingeniously so that his absence did not affect their number nor their excellent quality. He served for many years on the Faculty Board and as the Chairman of the Library Committee of the Institute.
It is not possible to conclude without mentioning that "Bob" or "H.P." as he was known affectionately was a jolly and warmhearted man with many friends throughout America, England and the Continent. At the same time, he was tough and courageous in defence of his principles and was never intimidated by rank or position, military or political. Affable as he was, he had no tolerance of sham or pretence in any form and made this clear on all occasions. He loved jokes and limericks and humerous poems in several languages. He had an inexhaustible fund of good stories and was the best of companions in all companies. He was loved almost to adoration not only by his family but also by his intimate circle of friends. His untimely death has taken away not only a great mathematical physicist and scientific statesman but also one of the most beloved of men.
WILLIAM A. FOWLER
Professor Robertson was born in Hoquiam in the State of Washington on 1903 January 27, the son of George Duncan and Anna McLeod Robertson. In 1923 he was married to Angela Turinsky. Two children were born to them: a son, George Duncan, and a daughter, Mariette. His wife and children survive him. Robertson received his bachelor's and master's degrees from the University of Washington in 1922 and 1923 and his doctor's degree from the California Institute of Technology in 1925 at the age of 22. He then studied as a National Research Fellow in Göttingen and Munich. From 1927 to 1929 he served as Assistant Professor of Mathematics at the California Institute of Technology. In 1929 he went to Princeton as Assistant Professor of Mathematical Physics and, after rising to a full professorship there in 1938, he returned to the California Institute as Professor of Mathematical Physics in 1947.
Robertson had exceptional mathematical powers coupled with a deep insight into physical processes. Early in his career he gave the solution of Einstein's cosmological equations for the case of a homogeneous and isotropic universe. This solution is incorporated in the "line element" which bears his name. In all of his papers, Robertson emphasized that this solution was independently discovered by A. J. Walker. It has served as the basis of many of the numerous papers which have subsequently been written on relativistic cosmology. In addition Robertson succeeded in obtaining a general solution for two-body problems in general relativity.
The discovery of the red shift-distance relation and of the expanding universe by Edwin Hubble opened a continuing field of theoretical investigations for Robertson. From the beginning he was closely associated with Hubble, Milton Humason and Richard Tolman, and this association extended in later years to the younger staff members of the Mount Wilson and Mount Palomar Observatories who continued the red shift measurements. Robertson undertook to express the consequences of the general theory of relativity in regard to the red shift-distance observations in the most precise and explicit form possible. The greatest difficulty in the interpretation of these observations lies in the fact that distance is measured indirectly through measurements on the apparent luminosity or magnitude of the brightest stars in galaxies or of the brightest galaxies in clusters of galaxies. First of all Robertson succeeded in establishing the correction for the effect of the red shift on apparent luminosity by proving quite generally that this latter quantity is proportional to the absolute luminosity divided by the square of the Doppler shift. He ultimately succeeded in establishing the second-order terms in the red shift-magnitude relations which take into account the acceleration or deceleration of the universal expansion as well as the evolutionary history of stellar or galactic systems. He pointed out that the various expanding cosmologies all agree, except in physical interpretation, on the mathematical nature of the first-order Hubble relation but that differing cosmologies gave differing theoretical values for the acceleration parameter in the second-order term. Thus Robertson pointed the way to the critical observational test of relativistic cosmologies and made clear the necessity for great care in correcting for evolutionary effects. These tests were begun in Robertson's lifetime using the 200-inch Hale telescope but they were by no means completed. Their completion in the decades to come will mark the final culmination of his contribution to science. Robertson, himself, remained aloof in the controversies between the advocates of the various theoretical cosmologies. He preferred to have laid the basis within the framework of general relativity on which these cosmologies could be put to the observational test. His point of view was expressed beautifully in the last lines of his article in the Astrophysical Journal for May, 1936: "In fine, we are inclined to believe that our investigations may in some measure strengthen, on purely formal grounds, the claims of the general theory of relativity; in any event, we maintain that it cannot be rejected on such grounds, and are the more content to rest the case with the empirical."
Recognition of Robertson's achievements as a scientist came with election to the National Academy of Sciences of the United States in 1951. In 1958 he was elected Foreign Secretary of the Academy. In addition to being a Fellow of the Royal Astronomical Society he was also a Fellow of the American Physical Society and a member of the American Mathematical Society, the American Philosophical Society, the American Astronomical Society, the Edinburgh Mathematical Society, Sigma Xi and Phi Beta Kappa.
An outstanding phase of Robertson's career was the way in which, during World War II and after, he turned from abstruse theoretical subjects to the practical problems of military strategy. His scientific interest turned to applied problems in elasticity, hydrodynamics and shock wave propagation. He won the respect of both scientists and military officers in his grasp of war problems, his keen analytical ability and his skill in bringing the results of scientific analysis into useful and understandable form. He served as scientific liaison officer to the London Mission of the Office of Scientific Research and Development from 1943 to 1946. From 1944 to 1947 he was an expert consultant to the office of the American Secretary of War. In 1946, he was awarded the Presidential Medal for Merit.
In the years after World War II Robertson continued to be heavily engaged in military advisory tasks. He spent two years as scientific adviser to the Supreme Commander of the Allied Forces in Europe. He spent an additional two years as Scientific Director of the Weapons System Evaluation Group in Washington, working directly with the Joint Chiefs of Staff. He served on numerous science advisory boards including the Defense Science Board as chairman, the President's Science Advisory Committee, the Science Advisory Group to NATO and others. His activities along these lines were not confined to government service. He was a trustee of the Systems Development Corporation, the Institute for Defense Analysis, and the Carnegie Endowment for International Peace and was a director of the Northrop Aviation Corporation.
In spite of his many outside activities, Robertson played his full part as a faculty member of the California Institute of Technology. He scheduled his lectures ingeniously so that his absence did not affect their number nor their excellent quality. He served for many years on the Faculty Board and as the Chairman of the Library Committee of the Institute.
It is not possible to conclude without mentioning that "Bob" or "H.P." as he was known affectionately was a jolly and warmhearted man with many friends throughout America, England and the Continent. At the same time, he was tough and courageous in defence of his principles and was never intimidated by rank or position, military or political. Affable as he was, he had no tolerance of sham or pretence in any form and made this clear on all occasions. He loved jokes and limericks and humerous poems in several languages. He had an inexhaustible fund of good stories and was the best of companions in all companies. He was loved almost to adoration not only by his family but also by his intimate circle of friends. His untimely death has taken away not only a great mathematical physicist and scientific statesman but also one of the most beloved of men.
WILLIAM A. FOWLER
Howard Percy Robertson's obituary appeared in Journal of the Royal Astronomical Society 3:2 (1962), 132-135.