No . 3699, SEPT. 21, 1940 NATURE 393 The significance of this conclusion lies in its theory of relativity and the quantum theory, and relation to what is probably the most funda­ is, we hold, an over-generalization of the fact that mentally important effect of modern physics­ those theories have shown that a little experience namely, the revision which it makes necessary in goes a long way in theory. The special theory of our ideas of that in our knowledge for which we relativity alone is an inadequate criterion by depend on experience and that which can be which to judge it, but that compact department acquired by pure reason. The transformation of of physics affords an excellent example of both the ihe t-eo-ordinate is not a fact of experience : it is power and the limitations of reason in the building­ a logical deduction from the experimental fact up of knowledge. By the wisdom of our ancestors, sometimes called the 'Fitzgerald contraction' and metrical physics has been constructed entirely in the of physics by which time is measured terms of one fundamental unit-that of length : in terms of the space covered by a specified moving all other units are, by definition, dependent on body. It can be shown, in facta, that the whole of that. The experimental discovery of the depen­ the special theory of relativity follows logically dence of length on velocity therefore creates a from the effect of the 'Fitzgerald contraction' on disturbance which travels through the whole of the traditional definitions of classical physics. physics, and its effect is to show that certain con­ There is no doubt that a great deal of knowledge ceptions, formerly thought to be independent and which has been acquired by experiment, and for fundamentally necessary, are actually different which we are still generally thought to be depen­ forms of others already adopted. The identity of dent thereon, is a necessary consequence of other mass and energy, and the unity of the electro­ knowledge. Sir Arthur Eddington takes an extreme magnetic field and of the space-time continuum, view in this matter, and maintains that the whole are examples. But these achievements in no way of the laws of physics could, in principle, have remove the dependence of laws of physics on been derived by reason without recourse to experience. They simply allow us to express in experience 4 • Those who accept the scientific simpler terms the regularities found in experience. tradition must hold this to be an obvious error, for We may perhaps look forward to the time when a a law of physics is by definition a rational state­ single conception-possibly a sufficiently elaborated ment of the regularities found in experience; 'space-time'-will suffice to express all the order hence, no experience, no law. Any purely rational which experience exhibits, and we may then pre­ deduction of what is apparently a law of physics dict all that lies ahead. But we can never be sure must be a deduction from certain premises, and if that, even in that event, our predictions will not those premises are not guaranteed by experience be falsified and our laws will not need amendment. they must be assumed arbitrarily. Other premises 1 NATURE, 144, 8S8 (1939). would have yielded other 'laws'; and only experi­ 2 NATURE, 145, 427 (1940). ' See "The Special Theory of Relativity" (Methuen's Monographs on ence can tell us which are the laws of physics. Physical Subjects. In the press). Eddington's contention is based on the general '"The Philosophy of Physical Science" (Camb. Univ. Press). OBITUARIES Prof. A. E. H. Love, F.R.S. Grammar School, Wolverhampton, from 1874 until ROF. A. E. H. LOVE, Sedleian professor of 1881. The then headmaster was Thomas Beach, a P natural philosophy in the University of Oxford, man of some force of caaracter ; and Love was died on June 5, 1940, at the age of seventy-seven. taught mathematics by the Rev. Henry Williams, Though of late years in frail health, he had been who afterwards succeeded Beach. Love maintained active in lecturing and attending · to University an attachment to his old school, giving an annual business up to the time of his brief .illness, and he mathematical prize. Love is said to have been a had seemed well and brisk when meeting his col­ little odd as a schoolboy-not an uncommon thing leagues at a sub-faculty meeting early in the for mathematicians-and a certain whimsical touch summer term. He was unmarried ; his sister Blanche, endeared him to his friends throughout later life. whose devotion to his welfare was extreme, survives He was awarded a sizarship at St. John's College, him. Cambridge, in 1881, and went into residence there in Augustus Edward Hough Love-the name Hough 1882. He became scholar of the College in June, 1884. arose from a connexion with the Cape astronomer of He was Second W rangier in Parts I and II of the that name-was born at Weston-super·Mare on Mathematical Tripos in 1885, between Anthony Berry April 17, 1863; his father was police-surgeon to the and H. W. Richmond (both of King's); he was placed Borough of W olverhampton, and Love attended the in Division I, Part III in 1886 and was awarded the © 1940 Nature Publishing Group 394 NATURE SEPT. 21, 1940, VoL. 146 First Smith's Prize in 1887. He held a fellowship at The treatise on the "Mathematical Theory of St. John's College from 1886 until 1899 and became Elasticity" stands in a class with Lamb's "Hydro­ a College lecturer (two of his colleagues b eing R. R. dynamics", and is a classic. If a comparison between Webb and Sir Joseph Larmor). This was a time of 'good' things is at all legitimate, it may be said that great mathematical activity for Love, and he was Love's work is if anything the more scholarly but elected of the Royal Society in 1894. It was the tougher r eading, as befitting a more intractable then, too, that there commenced his long association subject. Love was essentially a mathematician, with the London Mathematical Society ; besides delighting in partial differential equations and filling the presidential office, he served for fifteen spherical harmonics ; the eye to applic&tions was years as an honorary secretary, and was altogether there, but h e was no engineer. The "Elasticity", like thirty-three years on its Council. Lamb's "Hydrodynamics", is academic in character, Love was elected to the Sedleian chair in Oxford but what a joy does the academic reader derive from in 1899, and the increased leisure allowed him even it, once properly afloat on that inland sea ! Whether to increase his research activity in his chosen subjects it be the foundations of the subject, the equilibrium of elasticity, geodynamics and electrodynamics. He of strained bodies, the torsion of prisms, the won the Adams Prize at Cambridge in 1911 for an vibration of solids, the propagation of waves, the essay entitled "Some Problems in Geodynamics", bending of beams, or the theory of thin shells, the which was soon afterwards published. He was whole is verifiable, calm, controlled by the mind of awarded a Royal Medal in 1909, the De Morgan a master. Love was perhaps attracted to the subject Medal of the London Mathematical Society in 1926 because after a controversial start it had settled and, as a fitting tribute to his life-long devotion to down into a subject in which the principles were well mathematics, the Royal Society's Sylvester Medal in accepted and well understood ; the mathematician 1937. H e was elected an honorary fellow of St. John's could, up to a point, have complete confidence in the College in 1927, in which year also he became a foundation on which he was building. fellow of the Queen's College, Oxford. His inter­ Love's lectures at Oxford were ever models of national standing was recognized by his associate­ form, and he devoted much care to the preparation ship of the Academy of the Lincei and his election as of courses on subjects outside his researches- notably a corresponding member of the Institute of France. on relativity and the tensor researches. In this con­ Love will chiefly be remembered for two out­ nexion it is the more remarkable that in the "Elas­ standing achievements, his discovery of what after­ ticity" he scarcely recognizes that the components wards became known as 'Love waves' and his of strain on one hand and of stress on the other authorship of his treatise on the "Mathematical form tensors-three-dimensional symmetric t ensors Theory of Elasticity". It is a classical result that of a most instructive kind. His notation was in fact any disturbance in an elastic medium resolves itself unfortunate, as it concealed the tensor nature of into the propagation of trains of compressional and these entities ; his Xy and Zx for components of stress distortional (equivoluminal) waves in three dimen­ are quite frankly abominations of un-symmetricality, sions, but it is not immediately obvious that there and his omission of the factor t in his definitions of exists a mode of combination of such trains which the non-principal components of strain is disastrous results in the propagation of a disturbance in two in transformation formulre. But everything may be dimensions over the surface of a semi-infinite elastic forgiven to a man of Love's attractive geniality and body. Such a form of waves was discovered by Ray­ modesty of character.