Ernest Rutherford

Ernest Rutherford (August 30th 1871 with Brightwater, New Zealand - October 19th 1937 with Cambridge, England) is regarded as the father of the Nuclear physics. He discovered the radiations alpha, the radiations beta; he as discovered as the Radioactivité was accompanied by a disintegration of the chemical elements, which was worth a to him Nobel Prize of chemistry in 1908. It is still him which highlighted the existence of a Atomic nucleus, in which were joined together all the positive load and almost all the Masse of the Atome, and which made a success of very first the artificial Transmutation.

So during the first part of its life it was devoted exclusively to its research, it passed second half of its life to teach and direct the Laboratoire Cavendish to Cambridge, where the Neutron was discovered and where trained the physicists Niels Bohr and Robert Oppenheimer. Its influence in this field of the physics which he discovered was thus particularly important.

First years

Ernest Rutherford was the fourth of the twelve children of James and Martha Rutherford. His/her father was farmer, but also mechanic, Engineer, even Meunier, while his/her mother, before their marriage, was teacher. Both held so that their children receive a good education and can continue studies.

Ernest was characterized very quickly by its curiosity and its gifts for the Arithmétique. He was encouraged in that by his parents and his teacher, and proved to be a very brilliant pupil thereafter, which enabled him to enter in Nelson College and to spend three years there. He was also very gifted for the Rugby, and very popular in his school. The last year, it finished first in all the matters, which enabled him to enter to the university in Canterbury College, where it continued to exert the Rugby and where it took part in clubs of science and reflection.

The genius of Rutherford for the experimentation could at that time starts to appear: its first research showed that the Fer could be magnetized by high the Fréquence S, which was in oneself a discovery. Its excellent school results enabled him to continue its studies and its research during five years in all in this university - it had indeed gained the only purse of New Zealand to study mathematics, and survived the last year by giving courses.

It obtained thus the title of Maîtrise are arts with a double first class in mathematics and physics. In 1894, it obtained the title of science Baccalauréat what enabled him to go to continue its studies in England with the Laboratoire Cavendish with Cambridge under the direction of the discoverer of the electron, J.J. Thomson starting from 1895.

It was the first student one coming from overseas to obtain this possibility. Before leaving New Zealand, it became engaged to Mary Newton, an young girl of Christchurch.

Cambridge, 1895-1898

It first of all continued its work on the Hertzian waves and their reception at long distance. It made a remarkable talk of its work in front of the Cambridge Physical Society , and was published in the Philosophical Transactions of the Royal Society of London, rare fact for a so young researcher, and who got a great pride to him.

In December 1895, it started to work with Thomson being studied of the effect of the X-rays on a gas. He discovered whereas x-rays had the property to ionize the Air, since they could show that produced great quantities of charged particles, as much positive than negative, and than these particles could recombine to give neutral atoms. On its side, Rutherford then invented a technique to measure the speed of the Ion S, and their rate of recombination. In fact work definitively directed it in the way which made it famous.

Montreal, 1898-1907: radioactivity

In 1898, after three years spent with Cambridge and at the 27 years age, one proposes to him a pulpit of Physique to the Université McGill of Montreal, which it hastens to accept, seeing the occasion there to make come near him that which awaits it in New Zealand.

Becquerel discovers at that time (1896) that the Uranium emitted an unknown radiation, the “uranic radiation”.

Rutherford published in 1899 an essential paper, where he studied the way which these radiations could have to ionize the air, while placing uranium between two charged plates, and by measuring the current which passed. He thus studied the capacity of penetration of the radiations, by covering his uranium samples with metal sheets different thicknesses.

He noticed that ionization started by decreasing very quickly with the increase thickness of the sheets, then, beyond by a certain threshold, decreased very gently.

He deduced from it that uranium emitted two different radiations, because having different capacities of penetration. He named the least penetrating radiation the radiation alpha, and the most penetrating radiation (and which produced a less ionization inevitably since it crossed the air) the radiation beta.

In 1900, Rutherford marries Mary Newton, and from the marriage in 1901 the only girl is born from Rutherford, Eileen.

At that time, Rutherford studies the Thorium, and notes by using the same device as for uranium, than the fact of opening a door in the laboratory disturbs the experiment clearly, as if the movements of the air in the experiment could disturb it. It from of comes quickly with conclusion that thorium releases emanation, it also radioactive, since by aspiring the air which surrounds thorium, he realizes that this air easily lets pass the current, even at long distance from thorium.

He also notices that the emanations of thorium remain radioactive only one ten minutes, and that they are neutral particles. Their radioactivity is disturbed by no chemical reaction, nor change of conditions (temperature, electric field). It even finds that the radioactivity of these particles decrease exponentially, since the current which passes between the electrodes made in the same way, and thus discovers the period of the radioactive elements in 1900.

With the assistance of a chemist of Montreal, Frederick Soddy, it concludes in 1902 that the emanations of thorium are many radioactive atoms, but without being thorium, and that the radioactivity is thus accompanied by a disintegration of the elements.

This discovery of course caused a great agitation among the chemists, very attached to the concept of indestructibility of the matter. It is on this concept that most of the science of the time was built besides. This discovery is thus a true upheaval. But the quality of work of Rutherford could not leave of doubt. Pierre Curie itself will accept this idea later only two years, whereas it had already noted with Marie Curie that the radioactivity was accompanied by a loss of mass of the samples (it thought that the atoms lost weight without changing nature).

Work of Rutherford was recognized in 1903 by the Royal Society , which decreed to him the Médaille Rumford in 1904. It summarized the result of its research in one entitled book Radio-activité in 1904, where it explained why the radioactivity was not influenced by the conditions external of pressure and temperature, nor by the chemical reactions, but which it produced an heat emission higher than that of a chemical reaction. He also explained that new elements were produced, with different chemical characteristics, while the radioactive elements disappeared.

With Frederick Soddy, it estimates that the release of energy due to nuclear disintegrations is of: 20000 with: 100000 times more important than that which would result from a chemical reaction. It also puts forward the idea that such an energy could explain the energy released by the sun. With Rutt, it even estimates that if the Earth preserves a constant temperature (in all the cases as regards its core), it is undoubtedly due to the reactions of disintegration which occur in its center.

This idea of a great potential energy contained in the atoms will find one year after a theoretical beginning of confirmation with the discovery of Einstein of the equivalence mass-energy. Otto Hahn, the discoverer of nuclear fission, will come to study with Rutherford with McGill during a few months, following this work.

It starts since 1903 to raise questions about true nature of the alpha radiations, and in their making cross magnetic electric fields and from of deduced their speed, the sign (positive) of their load, and the relationship between their load and their mass. It is the way which will carry out it towards its most famous work.

During its stay with McGill, it will publish approximately 80 articles, and invented many devices without relationship with the nuclear physics.

Manchester, 1907-1919: the atomic nucleus

In 1907, it obtains a post of professor with the Université of Manchester, where it works with Hans Geiger. With this last, he invents a meter making it possible to detect the particles alpha emitted by the radioactive substances (outline of the future Geiger counter), because by ionizing the gas which is in the apparatus, they produce a detectable discharge.

In 1908, with one of its students, Thomas Royds, it definitively proves what one supposed, namely that the particles alpha are many cores of Hélium. Or rather, that the particles alpha are helium atoms once removed from their negative charges. To prove it, it isolates radioactive substance in a sufficiently thin material so that the particles alpha cross it indeed, but so that blocks all “emanation” of the radioactive elements, i.e. very product decay. It collects then the gas which is around the box which contains the samples, and analyzes its spectrum. It then finds there a great quantity of helium: the cores which are the particles alpha recovered of the electrons available.

It obtains the same year the Nobel Prize of chemistry for its work of 1902. It will preserve a small disappointment of it however, because it is considered above all like a physicist. One as of its famous quotations is “science, either it is physics, or it is philately. ”, undoubtedly wanting to mean by there that it placed physics above other sciences.

It is in 1911 that it will make its greater contribution to science by discovering the Atomic nucleus. It had observed in Montreal that by bombarding a fine sheet of Mica with particles alpha, one obtained a deflection of these particles. Geiger and Marsden remaking in a more thorough way these experiments and by using a gold sheet, noted that certain particles alpha were deviated of more than 90 degrees. Rutherford then put forth the assumption, whose Geiger and Marsden confronted the conclusions with the experiment, that in the center of the atom was to be a “core” almost containing all the mass and all the positive load of the atom, the determining electrons makes the size of the atom of it.

Cambridge, 1919-1937: the golden age of Cavendish

The same year, it succeeds J.J. Thomson with the Laboratory Cavendish, and becomes the director about it. It is the beginning of a golden age for the laboratory, and Rutherford, even if the research tasks of the latter will mark time. However, as from this time, its influence on research in the field of the nuclear physics is enormous. For example, in a conference which it gives in front of Royal Society, it refers already to the existence of the neutron and isotopes of hydrogen and helium. And it is at the Cavendish laboratory, under its impulse, that those will be discovered.

James Chadwick, discoverer of the neutron, Niels Bohr, which showed that the planetary model of Rutherford was not unstable, and Robert Oppenheimer, regarded as the father of the Atomic bomb, among those which counts studied at the laboratory of the time of Rutherford. Henry Moseley, which was the student one of Rutherford, showed by using the Diffraction X-rays that the atoms contained as many electrons as there were positive loads in the core, and than thus its results “strongly supported the sights of Bohr and Rutherford”.

The many courses that it gave to the Cavendish laboratory and the great number of contacts that it had with its students, gave of Rutherford the indication of a man extremely attached to the facts, more still than with the theory, which for him was some share only one simple “opinion”. This attachment with the experimental facts was the sign of a great rigor and a great honesty. When Fermi succeeds in disintegrating various elements using neutrons, he wrote to him to congratulate it to be itself “escaped theoretical physics”.

Fortunately however, Rutherford did not stop with the facts, and its great imagination made him foresee behind the facts, the theoretical consequences most remote, but it did not support that one complicates the things unnecessarily. It often made remarks on this subject with the visitors of the laboratory who came to expose their work to the students (amused) and the researchers, whatever the fame of the visitor. Its attachment with simplicity was almost proverbial. He said besides: “I am myself a simple man”.

Its authority at the Cavendish laboratory was not based on the fear which it could inspire. On the contrary, Rutherford was of a jovial nature, and it was known that its work advanced when it chantonnait in its laboratory. It was respected by its students less for its last work or the myth which surrounded it that for its attaching personality, its generosity and its intellectual authority, so much so that it was regarded as “the professor” of Cambridge.

It was called “the crocodile”, because as a crocodile which never sees its tail, it always looked in front of him.

This time is also for Rutherford that of the honors: he was president of the Royal Society of 1925 to 1930, and chair Academic Assistance Council which, in these politically disturbed times, helped the German academics who fled their country. He is also prize winner of the Médaille Copley in 1922, of the Franklin Médaille in 1924 and of the Faraday Lectureship of the Royal society off chemistry in 1936. He made his last voyage in New Zealand, his land native which he never forgot, in 1925 and was accepted like a hero.

It is in 1931 qu ' it was anobli, and obtained off the title of Baron Rutherford Nelson, off Cambridge. The same year died his/her single daughter, Eileen, nine days after having given rise to its fourth child. Rutherford was a physically vigorous man, and it entered to the hospital in 1937 for a minor operation, after being hurt while cutting trees in its property. On its return at his place, it seemed to go back without problem, when its state worsened suddenly. He died very abruptly, on October 19th and was buried with the Abbaye of Westminster, at the sides of Newton and Kelvin.

Its figure decorates from now on the tickets of 100 New Zealand dollars.

Quotations

The energy produced by the atom is rather unspecified. Whoever speaks to use it as energy source is beside its pumps. (free translation of The energy produced by the atom has very poor kind off thing. Anyone who expects has source off power from the transformation off thesis atoms is talking moonshine. , 1933)

Science is either of physics, or of philately. (free translation of All science is either physics gold stamp collecting , 1962)

I was always proud owing to the fact that I would be Néo-Zélandais. (translation of I cuts always been proud off the fact that I amndt has New Zealander , Auckland, 1925)

It is as incredible as if you fire a shell from 15 inches to a paper fabric part and that it returned to strike you. (free translation of incredible It was almost ace ace yew you fired has fifteen inch Shell At has part off tissue paper and it cam back to hit you , 1909)

See too

Experiment of Rutherford
museum Rutherford

Simple: Ernest Rutherford

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