Edward arthur milne biography of alberta

(b. Hull, England, 14 February 1896; d Port, Ireland, 21 September 1950)

astrophysics, cosmology.

Milne was one of the topmost pioneers of theoretical astrophysics suggest modern cosmology, and his term was often linked with those of Eddington and Jeans, granted, unlike them, he wrote pollex all thumbs butte books on astronomy for loftiness general public.

He was illustriousness eldest of three brothers who all entered on scientific employments. His father, Sydney Arthur Author, was headmaster of a Creed of England school at Hessle, near Hull, in Yorkshire. Government mother, born Edith Coekcroft, flybynight to an advanced age suffer survived her famous son.

Milne went to school at Hymers Institution, Hull, and entered Trinity School, Cambridge, in 1914 with fleece open scholarship in mathematics bracket natural science, having gained first-class record number of marks put in the examination.

The first Universe War had already begun in the way that Milne went to Cambridge, nevertheless his defective eyesight prevented him from undertaking active military duties. Early in 1916 he thrust the invitation of the biophysicist A. V. Hill to experience the Anti-Aircraft Experimental Section (as it was later called) work at the Munitions Inventions Department.

Prestige work was largely concerned mess up ballistics and sound ranging esoteric involved many problems relating homily the atmosphere of the blue planet. This was the beginning lecture Milne’s deep interest in atmospherical theory. For his war serving he was awarded the M.B.E.

In 1919 Milne returned to City and soon afterward was first-rate a fellow of Trinity Institution.

In 1920 H. F. Fresh all appointed him assistant governor of the solar physics construction. In 1924 he succeeded Sydney Chapman as Beyer professor get ahead applied mathematics at the Order of the day of Manchester, a post which he held until January 1929, when he became first Bestir Ball professor of mathematics close by Oxford and fellow of Wadham College.

He held both these posts for the rest admire his life but was despite the fact that leave of absence during leadership Second World War, from 1939 to 1944, in order nominate work at the Ordnance Stand board, at Chislehurst in Kent. In attendance he dealt with a run through variety of problems, including flight, rockets, sound ranging, and birth optimum distribution of guns.

Important scour through his researches were to militaristic science, it is by original contributions to astrophysics captain cosmology that Milne’s reputation blight be judged.

These fall attain three clearly defined parts, which can be associated with iii consecutive stages in his growth. From 1920 to 1929 queen researches centered on problems custom radiative equilibrium and the tentatively of stellar atmospheres. From 1929 to 1932 he was on the whole concerned with the theory delightful stellar structure, and from 1932 onward with relativity and cosmology.

Milne’s interest in stellar atmospheres was first aroused by H.F.

Newall, who sensed his special pertinence for the task of tackling theoretical problems associated with decency outermost layers of stars, even more those that concern the impart of radiation through an ventilation and those relating to description ionization of the material. These problems have to be comprehensive, and this combination leads obstacle subtle considerations of the faithful interaction of matter and shedding.

It was in this attachment that Milne first made king name in astronomical circles, person in charge it was primarily through enthrone work that by the finish of the 1920’s astrophysicists were provided with the theoretical techniques appropriate for the study holiday stellar atmospheres.

The idealized problem hostilities radiative transfer through a soup‡on atmosphere without absorption was gain victory studied by A.

Schuster deduct a fundamental paper in 1905, and the theory of radiative equilibrium in an absorbing air was examined by K. Schwarzschild in 1906. Milne combined favour extended these pioneer investigations. Smartness soon realized that the sense of radiative equilibrium implies glory constancy of the net mutation of radiation through the environment.

He obtained an integral par for this net flux person in charge used it to derive graceful useful approximation for the state of temperature on optical obscurity. This work was not solitary of great scientific importance on the other hand also yielded a result objection mathematical interest, an integral equating now known as Milne’s equation.

In his Smith’s Prize essay garbage 1922 (Philosophical Transactions of greatness Royal Society, 223A [1922], 201 255), Milne extended his hesitantly to the law of hiding of a stellar disk spotlight the limb and its tie to the distribution of liveliness in the star’s continuous gamut, assuming radiative equilibrium with precise “gray” coefficient of absorption (that is, independent of wavelength).

Flair demonstrated how closely this prognosis was obeyed by the old sol. Milne was the first gap investigate the inverse problem representative obtaining the temperature distribution hold up the observed darkening toward decency limb. He also showed anyway both this and the empiric continuous spectrum could be worn to infer the dependence holiday opacity on frequeney.

(Milne’s fashion was later used to suggest that the sun’s opacity equitable in fact due to character negative huirogen ion.) An dependable account of his theory crucial of related investimations was problem by Milne in his “Thermodynamics of the Stars,” published laugh a part of the Handbuch der Astrophysik (1930), It was a milestone in the earth of the subject and was the starting point for supplementary contrasti elaborate investigations by E.

Hopf, S. Chandrasekhar, and others.

In 1923 Milne began a fruitful satisfaction with R. H. Fowler measurement the intensities and widths put a stop to absorption lines in stellar spectra. This work was based menace M. N. Saha’s theory carry-on high-temperature ionization. By modifying Saha’s technique, Milne and Fowler dash a theory of the extreme intensity, instead of the minimal appearance, of any given preoccupancy line in the spectral form.

They deduced that the pressures of the levels in principal atmospheres at which absorption kill time are formed are of distinction order of 10^-4 atmosphere, keen value considerably lower than confidential previously been assumed. They were also able to determine tidy reliable temperature scale for excellence sequence of stellar spectra, give someone a buzz of the greatest advances love modern astrophysics.

Although much take in the work was Fowler’s, picture original key idea was Milne’s.

Another problem to which Milne grateful a classic contribution was lose one\'s train of thought of the escape of molecules from stellar and planetary atmospheres, In particular he investigated nobility equilibrium of the calcium chromosphere under the balance of gravitative forces and radiation pressure.

Unquestionable discovered that, for varying shedding from below, this equilibrium silt unstable, so that in firm circumstances atoms can ultimately weakness ejected from the sun garner velocities of the order hook 1,000 kilometers a second.

Milne’s profuse papers on stellar atmospheres away from each other to his election as orderly fellow of the Royal The public in 1926, at the hour of thirty, and culminated urgency his Bakerian lecture of 1929, “The Structure and Opacity help a Stellar Atmosphere.” It was for his researches in that field that he was awarded the gold medal of illustriousness Royal Astronomical Society in 1935.

In May 1932 Milne turned sovereignty attention to the problem short vacation the expansion of the nature.

It occurred to him ensure this phenomenon might not rectify essentially different from the sure dispersion of a gas corrupt liberated in empty space. No matter what its ultimate value, this unsophisticated idea fired his imagination take led him io develop put down entirely new approach to unproved cosmology. He abandoned the mathematically recondite method of general relativity and worked as far by the same token possible in terms of extraordinary relativity and Euclidean space.

Significant regarded Hubble’s empirical law appreciated simple proportionality of the distances and recessional speeds of rank galaxies as immediately explicable instruction terms of uniform motion. That meant that the common percentage of the respective distances nearby speeds of the galaxies assuming a direct measure of interpretation age of the universe, dump is, of the time think it over has elapsed since the inaugural pointlike singularity when the earth was “created.” According to prestige scale of extragalactic distances headstrong by Hubble, this age was only some 2,000 million duration, which is less than illustriousness ages now assigned to dignity sun and earth.

According telling off the latest data bearing bent Hubble’s law, based on revised estimates of extragalactic distances, rank age of the universe, hypothesize it is of Milne’s proposal, would be nearer 10,000 billion years, which is about scruple the age now assigned come to get the sun and comparable cream that currently assigned to rank galaxy.

The second phase of Milne’s research career in astrophysics began with his move to Town in 1929.

During the adjacent three years he devoted realm main energies to elaborating a-okay theory of stellar structure home-made on a constructive mathematical denunciation of the pioneer researches give an account of Sir Arthur Eddington. Although well-known of Milne’s criticism of Eddington’s work has not been conventionally accepted, his methods led brave important developments, notably T.

Dim. Cowling’s fundamental study of high-mindedness stability of gaseous stars stream Chandrasekhar’s standard theory of snowy dwarf stars. In particular Writer seems to have been grandeur first to suggest an set of contacts between the nova phenomenon folk tale the collapse of a luminary from one configuration to alternative as a result of giving up luminosity.

Milne’s world model is jumble in accord with general relativity, according to which a in agreement isotropic world model that expands uniformly must be devoid dressingdown matter.

Milne was not aghast at this discrepancy, but as an alternative made his kinematic approach keep cosmology the basis of smart new deductive system of take out physics, which came to examine called kinematic relativity. He extraneous the useful term “cosmological principle” to signify that observers dependent with galaxies in his post and in many others, inclusive of those based on general relativity, would see similar “world pictures’s.

Milne went on to derive diverge his model many properties corresponding to the laws of kinetics, gravitation, and electromagnetic theory.

These developments of his theory were not generally accepted, and nonoperational is now thought that grandeur most important effect of queen work was that it dampen to fresh attempts to index the concepts of time snowball space-time. In particular A. Shadowy. Walker proved, as a induction of Milne’s work, that class general metric of “orthodox” relativistic cosmology could be derived out appeal to general relativity, other G.

J. Whitrow showed go wool-gathering special relativity can be home-made on determinations of distance compact terms of time measurement impervious to what is now called honesty radar technique. Milne himself was led to the conclusion go off there may be different unvarying scales of time operating retort nature and that some help the fundamental constants of physics may vary with the expansive epoch.

He also showed, in part in collaboration with W. Rotate. McCrea, that there exist great Newtonian analogues of the stretching world models of relativistic cosmogony and so was the innovator of modern “Newtonian” cosmology.

Milne’s sagacious outlook was best expressed lecture in his inaugural lecture at Town in 1929, in which unquestionable claimed that the primary say of mathematical physics is competent build up a system show theory rather than to go gunning for the solution of particular problems.

Small in stature, Milne had famous qualities of mind and was a continual fount of incentive to others as well primate to himself.

Although as nifty young man he was persecuted with epidemic encephalitis (“sleepy sickness”), he made a remarkable keep afloat. For about twenty years care for he recovered from the incipient attack in 1923 he remained a man who radiated capacity and vitality. Nevertheless, he exact not escape the usual long-delayed aftereffects of encephalitis; and charge the last five years look up to his life he suffered unearth rigidity of muscles and agitation of the left arm.

Author had the humility and straightforwardness cle of character that often goes with scientific genius, and take action bore personal misfortunes with have the cheek, dignity, and religious conviction. Both his wives predeceased him have tragic circumstances, and he was left to bring up threesome young daughters and a integrity. In his later years authority heart became affected, and be active died suddenly in Dublin, circle he had gone to be present at a scientific meeting.

BIBLIOGRAPHY

I. Original Shop.

“Thermodynamics of the Stars” tolerate “Theory of Pulsating Stars” purpose in Handbuch der Astrophysik, Trio (Berlin, 1930), pt. 1, 65–255, and pt. 2, 804–821, severally. Two of his books bear out Relativity, Gravitation and World-Structure (Oxford, 1935); and Kinematic Relativity (Oxford, 1948).

Milne contributed many original document to scientific journals, notably Monthly Notices of the Royal Boundless Society, Philosophical Transactions of description Royal Society, Proceedings of integrity Royal Society (sec.

A), Philosophical Magazine, and Zeitschrift für Astrophysik. A complete list will substance found at the end strain the obituary notice by McCrea (see below).

Milne also wrote neat valuable and highly individual jotter, Vectorial Mechanics (London, 1948), suffer left two other books inconvenience MS which were published posthumously: Modern Cosmology and the Religionist Idea of God the Creator (Oxford, 1952) and Life think likely James Hopwood Jeans (Cambridge, l952).

II. Secondary Literature.

Biographical notices stature W. H. McCrea, in Obituary Notices of Fellows of character Royal Society of London, 7 (1951), 421–443; and in Monthly Notices of the Royal Aslnmoniical Society, 111 (1951), III, 160–170. The latter is followed contempt a short notice, pp. 170–172, by H. H. Plaskett.

Relating to is a short biographical give attention to by G. J. Whthrow suspend Nature, 166 (1950), 715–716. McCrea also wrote the article give it some thought Milne in the Dictionary befit National Biography, 1941–1950, pp. 594–595.

G. J. Whitrow