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Pol Adrien Moris Dirac — biography

Поль Дирак

Pol Adrien Moris Dirac (Поль Дирак) (1902-1984) — The English physicist, one of founders of a quantum mechanics, foreign corresponding member Academy of Sciences of the USSR[ru] (1931). Zodiac — Leo.

Has developed the quantum statistics (statistican Fermi - Dirac); the relativistic theory of a motion of an electron (the equation of Dirac, 1928), predicted a positron, and also an annihilation and a birth of pairs. Has offered a method of secondary quantization. Has put in pawn bottoms of a quantum electrodynamics and a gravitation quantum theory. The Nobel Prize (1933, together with Ervinom Shredingerom).

Pol Dirac was born on August, 8th, 1902, in Bristol, a county Gloucestershire, England.

Before arrival to Cambridge

Charlz Adrien Ladislas Dirac, the father of the future great physicist, has emigrated from Switzerland to England, and by 1902 it with wife Florenc and c three children[ru] (the Field had big brother and younger sister) lived in Bristol in the own house. In 1919 the father and all terms of a family became citizens of Britain.

The father of the Field earned teaching of the French language. Pupils did not love it, - it was too strict and exacting, - though should understand efficiencies of its pedagogical receptions. Lived it is closed. Subsequently Pol Dirac recollected: nobody came To our house behind an exception, maybe, few pupils of the father. We did not have any visitors. The father demanded, that in the house spoke in French (its native) language, contrary to desires of the wife and children, and it was one of the parents impeding dialogue. From here, probably, reticence of the Field and its gravitation to loneliness originates.

Fields have donated to study in school where his father taught. It was a little old-fashioned, but also rather solid educational institution which Dirac recollected, that it was ... Magnificent school of natural sciences and the modern languages. In it was not neither Latin, nor Greek to that I was very glad for I at all did not perceive ancient cultures. I was very happy, that could visit this school. I studied with 1914 for 1918, just during the First World War. Many guys have left school for the sake of nation service. As a result the senior classes have absolutely emptied. To fill a blank, began to advance younger in such degree in what they could cope with more difficult operation. It was very favourable me: I promptly have slipped elementary grades and at very early age have got acquainted with bottoms of mathematics, physics, chemistry at quite high level. I learnt mathematics under books which, as a rule, contained more than knew a class. Further he recollects, that at school ...Appreciated my fidelity to a science..., though in sports I was not accompanied by good luck .

Apparently, has played the plus role and that fact, that the school was located in the same building, as the technical college which had good laboratories.

In 1918 at the age of sixteen years Pol Dirac became the student of electrotechnical faculty of Bristol university who also was located in a building of its school and in three years has most advantageously ended it. Years of study at university are exclusively important for formation of the young scientist; here, in particular, he has got acquainted with a theory of relativity to which could play such major role in its further operation. It has gained much and from teacher Petera of the Milling cutter, able to inform to pupils the understanding of logic symmetry and beauty of mathematics, in particular, to geometry.

Though Pol Dirac studied well as the engineer it has appeared not claimed. Attempt to gain the grant at university in Cambridge also has not crowned success. Only in two years, after new attempt Dirac has gained the small grant and a smog become the post-graduate student, and in 1923 it has arrived to Cambridge.

Enchanting launch of the Field of Dirac

That has occurred the next some years, can seem by miracle. The yesterday's not engaged engineer, the author of only two small operations on the statistical mechanics, becomes the world famous physicist-theorist, whose first operations transmute it into the classic of a science and receive soon the Nobel Prize (1933).

Certainly, it was promoted essentially by scientific atmosphere of Cambridge. At that time it was one of recognised centres of theoretical physics where constantly came to tell about the operations of physics of all Europe. An important role played there Kapitsa's Club about which known English physicist John Desmond Bernal (1901-1971) wrote: It represented some kind of the Great court on all important questions of physics; people about major names were caused as on court, and were exposed to severe interrogation....

In 1924 P.Dirak became the term of club. There he, in particular, has got acquainted and with Verner Gejzenbergom, one of founders of a matrix quantum mechanics. To Dirac was then 23 years, and Heisenberg for a year was more senior. This meeting has appeared important for both. The next two years Dirac has developed a quantum mechanics mathematical apparatus - the theory of the representations, allowed to understand equality of several exteriorly various variants of the description in a quantum theory. Soon it had been offered a method of secondary quantization, the unclosed trajectory to the consecutive quantum description of an electromagnetic field. One of consequences of the quantum electrodynamics constructed thus were the deductions, concerning the forced radiation which already have laid down presently in a bottom of the whole direction in the physicist - a quantum electronics. And one year earlier simultaneously from Enriko Fermi and irrespective of it Dirac has developed statistics of particles with half-integer (i.e. Equal n h/2 p, where h - a Dirac constant, and n = 1/2, 3/2 etc.) a spin. And in a year by Dirac and Heisenberg the exchange interaction was open. But the most important achievement of that most fruitful pore was, unconditionally, occurrence of the equation of Dirac.

Relativistic electron

Two great theories of 20 centuries - a theory of relativity and a quantum mechanics - about two tens years developed parallelly, but is independent, though became more and more obvious, that their integrating is necessary and is inevitable. Actually, it has begun already at the beginning of quantum theory occurrence: after all the word quantum has been said for the first time by Max Planck with reference to electromagnetic radiation, and it is primordially relativistic object. But when there was an atom quantum theory when the electron in the beginning it seemed became object of viewing, that for its description enough the nonrelativistic wave equation. This equation offered Ervinom Shredingerom, is accompanied by an epithet nonrelativistic for the reason, that its view remains invariable only at the nonrelativistic transformations of Galilei for co-ordinates and time, but varies, if исPolзовать the relativistic Lorentz transformation laws.

It is possible to approach to a Schrodinger equation, using expression for a total energy as total of the kinetic and a potential energy and substituting for co-ordinates entering into their expressions and impulses subject functionals. But in the relativistic theory expression for energy varies: for the free particle it is proportional to a square root from the total of a quadrate of an impulse and a rest mass quadrate (increased by the fourth degree of a velocity of light). The square root, as is known, has two signs. Considering this circumstance and having used for root extraction the most graceful and refined mathematical "matrix" method, Dirac has come to the well-known equation carrying his name. This equation has been published in the operation which has left on February, 1st, 1928.

Subsequently, the author wrote: I have found out from this equation, that the electron possesses a spin equal 1/2, and a moment of magnet, and that value of a spin and a moment of magnet will be compounded with the observational. The gained effect was absolutely unexpected... I considered, that the elementary solution will be gained for a particle without a spin, and already then it will be necessary to enter a spin....

But the following was not less remarkable also: after all the square root has two signs, and was gained, that except states with plus, there are also states with the subzero energy. On levels with the subzero energy all electrons even if at first their energies were plus also should "fail". There was, apparently, an insuperable difficulty. But also here Dirac has telescoped idea which not only eliminated difficulty, but also unclosed the most fruitful prospects. This idea can seem now rather simple and almost obvious: it is enough to accept, that all levels with the subzero energy are occupied, and then, according to a Pauli's exclusion principle more any electron is not capable of them to be located.

Thus, there is a surprising new fashion: the vacuum is at all an empty place, not a state with zero number of electrons, and, on the contrary, sea from the perpetual number of electrons, but only we do not note these electrons, since. Their energies are subzero. However, it at all does not mean, that this sea is essentially observed: if any of electrons being in it, for example, from g-quantum, energy, sufficient is informed to translate it in a state with the plus energy there is that term as a pair birth: there is an electron with the plus energy, and on its place, at level with the subzero energy there is electron defect. In an exterior electric field (and in magnetic also) she behaves as a particle with the same mass, as well as at an electron, but with an electrical charge of an opposite sign (classical analogue of it it is possible to term a vial in a fluid which in the field of gravitation moves not downwards, and upwards).

Thus, the theory has led to a prediction of antiparticle of an electron. This particle termed as a positron, on experience Charles David Anderson really has soon found out. Now representation about antiparticles - partners-doubles of all particles - was included into physics.

Portrait accents

Full of an incessant creative voltage a life of the Field of Dirac exteriorly can seem quiet and poor events. In 1930 there was a first edition of its well-known book of a quantum mechanics Bottom. Level of mathematical severity and novelty of the approach to a material were not always clear even to the recognised theorists, some standings have seemed even to Heisenberg more symbolical, than it is necessary. But the feeling of perfection, mathematical beauty of the theory was extremely peculiar to Dirac. In 1966 when it came to Moscow (it happened in Russia some times, here it had many old friends) professor Dmitry Dmitrievich Ivanenko has asked to write it something a chalk on a wall of an office of chair of theoretical physics of the Physical office of the Moscow State University.

This inscription carefully maintained now under a glass, is that: Physical laws should have mathematical beauty (Physical laws should possess mathematical beauty). It is possible to term it as one of leading mottoes of its operation. Almost seriously he believed, that if the theory is beautiful, the nature can take advantage of it.

About the first arrival of Dirac to our country such story was maintained. At the international conference where it should arrive, for it with excitement and impatience waited. There was its book of Bottom, and it would be desirable to ask the author on much. The meeting was triumphal, Dirac directly on an armchair have set up on a table, and in such position it should preside... But further has disappointed many: Dirac or answered all questions Pol: It is written in my book!, or I do not know it!. But soon this position, in own way terrain clearancely logical, has been understood and estimated. (About Dirac in general there is a set of similar stories, it not without reason became the favourite character[ru] of collections like Physicists joke).

It is possible to note, that visitings of Russia did not remain not noted. In 1954 when Fields have invited to Princeton, the US State department has given up to it in the entry visa as Dirac considered, because of them. Dirac - the author of articles in the Major Soviet encyclopaedia and the Physical encyclopaedic dictionary (publishing house Soviet encyclopaedia, nowadays the Major Russian encyclopaedia).

With 1932 for 1967 Pol Dirac was the professor of the Cambridge university (here it occupied honourable Lukasovsky chair which was headed in due time by Isaak Newton), in 1969, according to blanket rules, he has retired and has moved to Florida where worked at centre of theoretical physics and at staff university. It prolonged many begun before operation, in particular, developed a hypothesis about a magnetic charge (the Monopole of Dirac), about dependence of a gravitational constant on time, trying to find the problem solution divergence (i.e. Formally perpetually great values which were given by a quantum theory of a field for a number of physical quantities), has entered concept indefinite metrics (i.e. Supposing states as from the plus. And the subzero probability), has constructed the blanket theory of classical fields, has offered the muon theory as excited vibrational state of an electron, wrote much.

Almost till last day it remains is true to a habit to long, as a rule - to lonely walks.

Pol Dirac has died on October, 20th, 1984, in Tallahassee, the USA[ru].

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