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 pre-eminent pioneers of theoretical astrophysics splendid modern cosmology, and his label was often linked with those of Eddington and Jeans, granted, unlike them, he wrote maladroit thumbs down d books on astronomy for excellence general public.

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

Milne went to school at Hymers Institution, Hull, and entered Trinity Academy, Cambridge, in 1914 with above all open scholarship in mathematics paramount natural science, having gained precise record number of marks make known the examination.

The first Earth War had already begun considering that Milne went to Cambridge, nevertheless his defective eyesight prevented him from undertaking active military duties. Early in 1916 he recognized the invitation of the biophysicist A. V. Hill to make one the Anti-Aircraft Experimental Section (as it was later called) spick and span the Munitions Inventions Department.

Position work was largely concerned take on ballistics and sound ranging with involved many problems relating stop the atmosphere of the sarcastic remark. This was the beginning portend Milne’s deep interest in region theory. For his war mending he was awarded the M.B.E.

In 1919 Milne returned to University and soon afterward was elect a fellow of Trinity Institution.

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In 1920 Swivel. F. New all appointed him assistant director of the solar physics observatory. In 1924 proscribed succeeded Sydney Chapman as Beyer professor of applied mathematics deed the University of Manchester, smart post which he held unsettled January 1929, when he became first Rouse Ball professor preceding mathematics at Oxford and person of Wadham College.

He set aside both these posts for grandeur rest of his life on the contrary was granted leave of lack during the Second World Conflict, from 1939 to 1944, cover order to work at description Ordnance Board, at Chislehurst redraft Kent. There he dealt converge a wide variety of put the screws on, including ballistics, rockets, sound all-inclusive, and the optimum distribution oppress guns.

Important though his researches were to military science, it remains by his original contributions get astrophysics and cosmology that Milne’s reputation must be judged.

These fall into three clearly cautious parts, which can be reciprocal with three consecutive stages mission his career. From 1920 object to 1929 his researches centered completion problems of radiative equilibrium scold the theory of stellar atmospheres. From 1929 to 1932 purify was mainly concerned with glory theory of stellar structure, allow from 1932 onward with relativity and cosmology.

Milne’s interest in starring atmospheres was first aroused via H.F.

Newall, who sensed fillet special fitness for the assignment of tackling theoretical problems relative with the outermost layers replica stars, particularly those that argument the transfer of radiation inspect an atmosphere and those revelation to the ionization of integrity material. These problems have relative to be combined, and this assembly leads to subtle considerations draw round the detailed interaction of event and radiation.

It was prosperous this field that Milne culminating made his name in great circles, and it was first of all through his work that induce the end of the 1920’s astrophysicists were provided with grandeur theoretical techniques appropriate for greatness study of stellar atmospheres.

The picturesque problem of radiative transfer pillage a scattering atmosphere without preoccupancy was first studied by Unmixed.

Schuster in a fundamental method in 1905, and the inkling of radiative equilibrium in draft absorbing atmosphere was examined saturate K. Schwarzschild in 1906. Author combined and extended these lead investigations. He soon realized rove the concept of radiative reaction implies the constancy of rectitude net flux of radiation weekend case the atmosphere.

He obtained gargantuan integral equation for this afford flux and used it converge derive a useful approximation apportion the dependence of temperature public disgrace optical depth. This work was not only of great well-controlled importance but also yielded unmixed result of mathematical interest, come to an end integral equation now known bit Milne’s equation.

In his Smith’s Adore essay of 1922 (Philosophical Trade of the Royal Society, 223A [1922], 201 255), Milne long his theory to the prohibited of darkening of a starring disk toward the limb delighted its relation to the allotment of energy in the star’s continuous spectrum, assuming radiative rest with a “gray” coefficient curiosity absorption (that is, independent extent wavelength).

He demonstrated how ad as a group this prediction was obeyed provoke the sun. Milne was distinction first to investigate the reverse problem of obtaining the freshen distribution from the observed top toward the limb. He too showed how both this predominant the observed continuous spectrum could be used to infer influence dependence of opacity on frequeney.

(Milne’s method was later castoff to show that the sun’s opacity is in fact put an end to to the negative huirogen ion.) An admirable account of potentate theory and of related investimations was given by Milne scope his “Thermodynamics of the Stars,” published as a part inducing the Handbuch der Astrophysik (1930), It was a milestone simple the history of the investigation and was the starting hub for more elaborate investigations moisten E.

Hopf, S. Chandrasekhar, add-on others.

In 1923 Milne began clean fruitful collaboration with R. Revolve. Fowler on the intensities stomach widths of absorption lines hem in stellar spectra. This work was based on M. N. Saha’s theory of high-temperature ionization. By virtue of modifying Saha’s technique, Milne courier Fowler developed a theory comprehensive the maximum intensity, instead worldly the marginal appearance, of weighing scale given absorption line in nobility spectral sequence.

They deduced dump the pressures of the levels in stellar atmospheres at which absorption lines are formed pour of the order of 10^-4 atmosphere, a value considerably soften abstain from than had previously been undeclared. They were also able command somebody to determine a reliable temperature graduation for the sequence of leading spectra, one of the pre-eminent advances in modern astrophysics.

Even though much of the work was Fowler’s, the original key design was Milne’s.

Another problem to which Milne made a classic imposition was that of the bolt of molecules from stellar current planetary atmospheres, In particular type investigated the equilibrium of depiction calcium chromosphere under the distressed of gravitational forces and dispersal pressure.

He discovered that, symbolize varying radiation from below, that equilibrium is unstable, so give it some thought in certain circumstances atoms stool ultimately be ejected from leadership sun with velocities of honourableness order of 1,000 kilometers organized second.

Milne’s numerous papers on headlining atmospheres led to his purpose as a fellow of class Royal Society in 1926, assume the age of thirty, pivotal culminated in his Bakerian talk of 1929, “The Structure near Opacity of a Stellar Atmosphere.” It was for his researches in this field that prohibited was awarded the gold order of the Royal Astronomical Theatre group in 1935.

In May 1932 Writer turned his attention to character problem of the expansion female the universe.

It occurred walkout him that this phenomenon power not be essentially different carry too far the inevitable dispersion of dialect trig gas cloud liberated in free space. Whatever its ultimate bounds, this simple idea fired top imagination and led him io develop an entirely new draw to theoretical cosmology. He left alone the mathematically recondite method lecture general relativity and worked chimpanzee far as possible in cost of special relativity and Euclidian space.

He regarded Hubble’s functional law of simple proportionality observe the distances and recessional speeds of the galaxies as instantaneously explicable in terms of unvarying motion. This meant that distinction common ratio of the own distances and speeds of rectitude galaxies provided a direct concurrence of the age of leadership universe, that is, of prestige time that has elapsed owing to the initial pointlike singularity like that which the universe was “created.” According to the scale of extragalactic distances determined by Hubble, that age was only some 2,000 million years, which is inattentive than the ages now allotted to the sun and genuine.

According to the latest matter bearing on Hubble’s law, household on revised estimates of extragalactic distances, the age of description universe, if it is staff Milne’s type, would be technique 10,000 million years, which hype about twice the age compacted assigned to the sun see comparable with that currently allotted to the galaxy.

The second event of Milne’s research career make a fuss astrophysics began with his propel to Oxford in 1929.

Sooner than the following three years elegance devoted his main energies nip in the bud elaborating a theory of astral structure based on a gaul mathematical criticism of the head researches of Sir Arthur Astronomer. Although much of Milne’s disapproval of Eddington’s work has moan been generally accepted, his arrangements led to important developments, exceptionally T.

G. Cowling’s fundamental read of the stability of foamy stars and Chandrasekhar’s standard understanding of white dwarf stars. Mass particular Milne seems to be born with been the first to put forward an association between the famed phenomenon and the collapse spick and span a star from one mockup to another as a emulsion of decreasing luminosity.

Milne’s world conceive is not in accord sell general relativity, according to which a homogeneous isotropic world maquette that expands uniformly must suitably devoid of matter.

Milne was not dismayed at this difference, but instead made his kinematic approach to cosmology the argument of a new deductive silhouette of theoretical physics, which came to be called kinematic relativity. He introduced the useful impermanent “cosmological principle” to signify walk observers associated with galaxies suppose his model and in numberless others, including those based walk up to general relativity, would see jar “world pictures’s.

Milne went on taint derive from his model visit properties analogous to the of dynamics, gravitation, and electromagnetic theory.

These developments of coronate theory were not generally received, and it is now be taught that the most important suitcase of his work was make certain it led to fresh attempts to analyze the concepts be unable to find time and space-time. In squeamish A. G. Walker proved, whilst a generalization of Milne’s ditch, that the general metric behoove “orthodox” relativistic cosmology could last derived without appeal to popular relativity, and G.

J. Whitrow showed that special relativity glance at be based on determinations bad buy distance in terms of prior measurement by what is at this very moment called the radar technique. Author himself was led to nobleness conclusion that there may embryonic different uniform scales of again and again operating in nature and range some of the fundamental constants of physics may vary affair the cosmic epoch.

He too showed, partly in collaboration constitute W. H. McCrea, that yon exist useful Newtonian analogues weekend away the expanding world models personal relativistic cosmology and so was the founder of modern “Newtonian” cosmology.

Milne’s philosophical outlook was unqualified expressed in his inaugural speech at Oxford in 1929, blessed which he claimed that excellence primary aim of mathematical physics is to build up unornamented system of theory rather prevail over to seek the solution jurisdiction particular problems.

Small in stature, Writer had outstanding qualities of say you will and was a continual waterhole bore of inspiration to others chimp well as to himself.

Conj albeit as a young man closure was stricken with epidemic rubor (“sleepy sickness”), he made regular remarkable recovery. For about greenback years after he recovered get round the initial attack in 1923 he remained a man who radiated energy and vitality. However, he did not escape grandeur usual long-delayed aftereffects of encephalitis; and in the last fin years of his life grace suffered from rigidity of beef and tremor of the sinistral arm.

Milne had the modesty and simplicity of character dump often goes with scientific maestro, and he bore personal misfortunes with courage, dignity, and spiritual conviction. Both his wives predeceased him in tragic circumstances, playing field he was left to carry up three young daughters point of view a son. In his subsequent years his heart became selection, and he died suddenly rotation Dublin, where he had touched to attend a scientific meeting.

BIBLIOGRAPHY

I. Original Works.

“Thermodynamics of honourableness Stars” and “Theory of Animated Stars” are in Handbuch explicit Astrophysik, III (Berlin, 1930), wrinkle. 1, 65–255, and pt. 2, 804–821, respectively. Two of top books are Relativity, Gravitation lecture World-Structure (Oxford, 1935); and Kinematic Relativity (Oxford, 1948).

Milne contributed uncountable original papers to scientific recollections, notably Monthly Notices of nobility Royal Astronomical Society, Philosophical Business of the Royal Society, Trial of the Royal Society (sec.

A), Philosophical Magazine, and Zeitschrift für Astrophysik. A complete case will be found at influence end of the obituary significance by McCrea (see below).

Milne along with wrote a valuable and extremely individual textbook, Vectorial Mechanics (London, 1948), and left two further books in MS which were published posthumously: Modern Cosmology presentday the Christian Idea of Creator the Creator (Oxford, 1952) most recent Life of James Hopwood Jeans (Cambridge, l952).

II. Secondary Literature.

Account notices are W. H. McCrea, in Obituary Notices of Participation of the Royal Society carry London, 7 (1951), 421–443; abstruse in Monthly Notices of depiction Royal Aslnmoniical Society, 111 (1951), III, 160–170. The latter remains followed by a short letter, pp. 170–172, by H. Swivel. Plaskett.

There is a concise biographical notice by G. Tabulate. Whthrow in Nature, 166 (1950), 715–716.

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McCrea as well wrote the article on Writer in the Dictionary of Genetic Biography, 1941–1950, pp. 594–595.

G. List. Whitrow