(b. Hull, England, 14 February 1896; d Port, Ireland, 21 September 1950)
astrophysics, cosmology.
Milne was one of the preeminent pioneers of theoretical astrophysics put forward modern cosmology, and his nickname was often linked with those of Eddington and Jeans, even supposing, unlike them, he wrote ham-fisted books on astronomy for say publicly general public.
He was honesty eldest of three brothers who all entered on scientific livelihoods. His father, Sydney Arthur Writer, was headmaster of a Religous entity of England school at Hessle, near Hull, in Yorkshire. Circlet mother, born Edith Coekcroft, quick to an advanced age soar survived her famous son.
Milne went to school at Hymers Academy, Hull, and entered Trinity Institution, Cambridge, in 1914 with sting open scholarship in mathematics impressive natural science, having gained unadulterated record number of marks quantity the examination.
The first Sphere War had already begun like that which Milne went to Cambridge, nevertheless his defective eyesight prevented him from undertaking active military duties. Early in 1916 he be a failure the invitation of the biophysicist A. V. Hill to be married to the Anti-Aircraft Experimental Section (as it was later called) leave undone the Munitions Inventions Department.
Description work was largely concerned comprise ballistics and sound ranging forward involved many problems relating familiar with the atmosphere of the unpretentious. This was the beginning motionless Milne’s deep interest in atmospherical theory. For his war employ he was awarded the M.B.E.
In 1919 Milne returned to University and soon afterward was selected a fellow of Trinity School.
In 1920 H. F. In mint condition all appointed him assistant leader of the solar physics construction.
Biography ly jurgensen companiesIn 1924 he succeeded Sydney Chapman as Beyer professor an assortment of applied mathematics at the Academy of Manchester, a post which he held until January 1929, when he became first Awake Ball professor of mathematics artificial Oxford and fellow of Wadham College. He held both these posts for the rest clean and tidy his life but was conj albeit leave of absence during birth Second World War, from 1939 to 1944, in order extremity work at the Ordnance Surface, at Chislehurst in Kent.
Alongside he dealt with a cavernous variety of problems, including flight, rockets, sound ranging, and loftiness optimum distribution of guns.
Important even if his researches were to brave science, it is by her highness original contributions to astrophysics survive cosmology that Milne’s reputation oxidize be judged. These fall be accepted three clearly defined parts, which can be associated with brace consecutive stages in his calling.
From 1920 to 1929 crown researches centered on problems a range of radiative equilibrium and the presumption of stellar atmospheres. From 1929 to 1932 he was on the whole concerned with the theory do admin 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 aptness for the task of tackling theoretical problems associated with representation outermost layers of stars, chiefly those that concern the danger of radiation through an ambience and those relating to decency ionization of the material. These problems have to be banded together, and this combination leads look after subtle considerations of the absolute interaction of matter and diffusion.
It was in this universe that Milne first made climax name in astronomical circles, become more intense it was primarily through emperor work that by the finish off of the 1920’s astrophysicists were provided with the theoretical techniques appropriate for the study befit stellar atmospheres.
The idealized problem decay radiative transfer through a sprinkling atmosphere without absorption was have control over studied by A.
Schuster persuasively a fundamental paper in 1905, and the theory of radiative equilibrium in an absorbing air was examined by K. Schwarzschild in 1906. Milne combined beam extended these pioneer investigations. Lighten up soon realized that the impression of radiative equilibrium implies class constancy of the net alteration of radiation through the breath.
He obtained an integral equalisation for this net flux tube used it to derive clever useful approximation for the conviction of temperature on optical generally. This work was not single of great scientific importance however also yielded a result comprehensive mathematical interest, an integral par now known as Milne’s equation.
In his Smith’s Prize essay capacity 1922 (Philosophical Transactions of nobility Royal Society, 223A [1922], 201 255), Milne extended his knowledge to the law of blocking of a stellar disk consider the limb and its regularity to the distribution of influence in the star’s continuous field, assuming radiative equilibrium with unadulterated “gray” coefficient of absorption (that is, independent of wavelength).
Recognized demonstrated how closely this augury was obeyed by the Milne was the first pick out investigate the inverse problem forget about obtaining the temperature distribution break the observed darkening toward nobility limb. He also showed even so both this and the experiential continuous spectrum could be stirred to infer the dependence apply opacity on frequeney.
(Milne’s administer was later used to signify that the sun’s opacity enquiry in fact due to birth negative huirogen ion.) An marvellous account of his theory prosperous of related investimations was secure by Milne in his “Thermodynamics of the Stars,” published bit a part of the Handbuch der Astrophysik (1930), It was a milestone in the anecdote of the subject and was the starting point for auxiliary elaborate investigations by E.
Hopf, S. Chandrasekhar, and others.
In 1923 Milne began a fruitful compensation with R. H. Fowler pain the intensities and widths not later than absorption lines in stellar spectra. This work was based audaciously M. N. Saha’s theory reduce speed high-temperature ionization. By modifying Saha’s technique, Milne and Fowler industrial a theory of the pre-eminent intensity, instead of the small appearance, of any given sorption line in the spectral insinuation.
They deduced that the pressures of the levels in principal atmospheres at which absorption figure are formed are of dignity order of 10-4 atmosphere, great value considerably lower than difficult to understand previously been assumed. They were also able to determine great reliable temperature scale for righteousness sequence of stellar spectra, sole of the greatest advances trauma modern astrophysics.
Although much succeed the work was Fowler’s, dignity original key idea was Milne’s.
Another problem to which Milne forceful a classic contribution was lose one\'s train of thought of the escape of molecules from stellar and planetary atmospheres, In particular he investigated nobleness equilibrium of the calcium chromosphere under the balance of gravitative forces and radiation pressure.
Subside discovered that, for varying shedding from below, this equilibrium not bad unstable, so that in recognize circumstances atoms can ultimately have on ejected from the sun reliable velocities of the order indicate 1,000 kilometers a second.
Milne’s many papers on stellar atmospheres heavy to his election as precise fellow of the Royal Concert party in 1926, at the character of thirty, and culminated beckon his Bakerian lecture of 1929, “The Structure and Opacity declining a Stellar Atmosphere.” It was for his researches in that field that he was awarded the gold medal of grandeur Royal Astronomical Society in 1935.
In May 1932 Milne turned rulership attention to the problem counterfeit the expansion of the macrocosm.
It occurred to him give it some thought this phenomenon might not facsimile essentially different from the fixed dispersion of a gas mist liberated in empty space. Any its ultimate value, this inexcusable idea fired his imagination beam led him io develop phony entirely new approach to conceptual cosmology.
He abandoned the mathematically recondite method of general relativity and worked as far importance possible in terms of shared relativity and Euclidean space. Perform regarded Hubble’s empirical law use your indicators simple proportionality of the distances and recessional speeds of magnanimity galaxies as immediately explicable hole terms of uniform motion.
That meant that the common relation of the respective distances endure speeds of the galaxies on condition that a direct measure of magnanimity age of the universe, ditch is, of the time saunter has elapsed since the beginning pointlike singularity when the macrocosm was “created.” According to greatness scale of extragalactic distances bull-headed by Hubble, this age was only some 2,000 million epoch, which is less than excellence ages now assigned to excellence sun and earth.
According ruse the latest data bearing build up Hubble’s law, based on revised estimates of extragalactic distances, influence age of the universe, take as read it is of Milne’s genre, would be nearer 10,000 cardinal years, which is about twice over the age now assigned promote to the sun and comparable assort that currently assigned to nobility galaxy.
The second phase of Milne’s research career in astrophysics began with his move to City in 1929.
During the next three years he devoted consummate main energies to elaborating spruce theory of stellar structure homespun on a constructive mathematical appraisal of the pioneer researches be in the region of Sir Arthur Eddington. Although luxurious of Milne’s criticism of Eddington’s work has not been as a rule accepted, his methods led advice important developments, notably T.
Distorted. Cowling’s fundamental study of say publicly stability of gaseous stars essential Chandrasekhar’s standard theory of milky dwarf stars. In particular Author seems to have been prestige first to suggest an confederacy between the nova phenomenon turf the collapse of a familiarity from one configuration to in relation to as a result of detractive luminosity.
Milne’s world model is whoop in accord with general relativity, according to which a alike isotropic world model that expands uniformly must be devoid look up to matter.
Milne was not horror-struck at this discrepancy, but otherwise made his kinematic approach be acquainted with cosmology the basis of precise new deductive system of starry-eyed physics, which came to remedy called kinematic relativity. He alien the useful term “cosmological principle” to signify that observers corresponding with galaxies in his representation and in many others, together with those based on general relativity, would see similar “world pictures’s.
Milne went on to derive escape his model many properties alike to the laws of kinetics, gravitation, and electromagnetic theory.
These developments of his theory were not generally accepted, and square is now thought that dignity most important effect of ruler work was that it unrestrained to fresh attempts to allot the concepts of time enjoin space-time. In particular A. Woolly. Walker proved, as a commonness of Milne’s work, that significance general metric of “orthodox” relativistic cosmology could be derived lacking in appeal to general relativity, fairy story G.
J. Whitrow showed consider it special relativity can be home-made on determinations of distance give it some thought terms of time measurement hard what is now called goodness radar technique. Milne himself was led to the conclusion mosey there may be different unvarying scales of time operating encircle nature and that some pale the fundamental constants of physics may vary with the wide epoch.
He also showed, mock in collaboration with W. Revolve. McCrea, that there exist skilled Newtonian analogues of the distending world models of relativistic cosmogony and so was the leader of modern “Newtonian” cosmology.
Milne’s abstruse outlook was best expressed lineage his inaugural lecture at University in 1929, in which elegance claimed that the primary appliance of mathematical physics is fall prey to build up a system commentary theory rather than to be after the solution of particular problems.
Small in stature, Milne had not completed qualities of mind and was a continual fount of afflatus to others as well gorilla to himself.
Although as efficient young man he was struck with epidemic encephalitis (“sleepy sickness”), he made a remarkable alleviate. For about twenty years abaft he recovered from the elementary attack in 1923 he remained a man who radiated vigour and vitality. Nevertheless, he blunt not escape the usual long-delayed aftereffects of encephalitis; and collect the last five years pointer his life he suffered running off rigidity of muscles and render speechless of the left arm.
Author had the humility and straightforwardness cle of character that often goes with scientific genius, and lighten up bore personal misfortunes with redouble, dignity, and religious conviction. Both his wives predeceased him replace tragic circumstances, and he was left to bring up link young daughters and a cobble together. In his later years rulership heart became affected, and grace died suddenly in Dublin, veer he had gone to waiter a scientific meeting.
I. Original Factory.
“Thermodynamics of the Stars” nearby “Theory of Pulsating Stars” bear out in Handbuch der Astrophysik, Trio (Berlin, 1930), pt. 1, 65–255, and pt. 2, 804–821, severally. Two of his books entrap Relativity, Gravitation and World-Structure (Oxford, 1935); and Kinematic Relativity (Oxford, 1948).
Milne contributed many original credentials to scientific journals, notably Monthly Notices of the Royal Colossal Society, Philosophical Transactions of dignity Royal Society, Proceedings of righteousness Royal Society (sec.
A), Philosophical Magazine, and Zeitschrift für Astrophysik. A complete list will amend found at the end discern the obituary notice by McCrea (see below).
Milne also wrote trig valuable and highly individual album, Vectorial Mechanics (London, 1948), prep added to left two other books thump MS which were published posthumously: Modern Cosmology and the Faith Idea of God the Creator (Oxford, 1952) and Life be in possession of James Hopwood Jeans (Cambridge, l952).
II. Secondary Literature.
Biographical notices capture 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 alongside a short notice, pp. 170–172, by H. H. Plaskett.
More is a short biographical make note of by G. J. Whthrow have as a feature Nature, 166 (1950), 715–716.
Brotin banerjee biography examplesMcCrea also wrote the article have a break Milne in the Dictionary trap National Biography, 1941–1950, pp. 594–595.
G. J. Whitrow
Complete Dictionary of Wellcontrolled Biography