Ernest Rutherford, Baron Rutherford of Nelson (30 August 1871 – 19 October 1937) was a New Zealandphysicist andchemist who was a pioneering researcher in bothatomic andnuclear physics. He has been described as "the father of nuclear physics"[8] and "the greatestexperimentalist sinceMichael Faraday."[9] In 1908, he was awarded theNobel Prize in Chemistry "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances." He was the firstOceanian Nobel laureate, and the first to perform Nobel-awarded work in Canada.
Rutherford's discoveries include the concept of radioactivehalf-life, the radioactive elementradon, and the differentiation and naming ofalpha andbeta radiation. Together withThomas Royds, Rutherford is credited with proving that alpha radiation is composed ofhelium nuclei.[10][11] In 1911, he theorised thatatoms have theircharge concentrated in a very smallnucleus.[12] He arrived at this theory through his discovery and interpretation ofRutherford scattering during thegold foil experiment performed byHans Geiger andErnest Marsden. In 1912, he invitedNiels Bohr to join his lab, leading to theBohr model of the atom. In 1917, he performed the first artificially inducednuclear reaction by conducting experiments in which nitrogen nuclei were bombarded with alpha particles. These experiments led him to discover the emission of a subatomic particle that he initially called the "hydrogen atom", but later (more precisely) renamed theproton.[13][14] He is also credited with developing theatomic numbering system alongsideHenry Moseley. His other achievements include advancing the fields ofradio communications andultrasound technology.
Ernest Rutherford was born on 30 August 1871 inBrightwater, New Zealand,[15] the fourth of twelve children of James Rutherford, an immigrant farmer and mechanic fromPerth, Scotland, and Martha Thompson, a schoolteacher fromHornchurch, England.[15][16][17] Rutherford's birth certificate was mistakenly written as 'Earnest'. He was known by his family as Ern.[15][17]
When Rutherford was age 5, he moved to Foxhill, New Zealand, and attended Foxhill School. At 11 in 1883, the Rutherford family moved toHavelock, a town in theMarlborough Sounds. The move was made to be closer to the flax mill Rutherford's father developed.[17] Ernest studied atHavelock School.[18]
In 1887, on his second attempt, he won a scholarship to study atNelson College.[17] On his first examination attempt, he had the highest mark of anyone from Nelson.[19] When he was awarded the scholarship, he had received 580 out of 600 possible marks.[20] After being awarded the scholarship, Havelock School presented him with a five-volume set of books titledThe Peoples of the World.[21] He studied at Nelson College between 1887 and 1889, and was head boy in 1889. He also played in the school's rugby team.[17] He was offered a cadetship in government service, but he declined as he still had 15 months of college remaining.[22]
In 1889, after his second attempt, he won ascholarship to study atCanterbury College,University of New Zealand, between 1890 and 1894. He participated in itsdebating society and the Science Society.[17] At Canterbury, he was awarded a complexB.A. in Latin, English and Maths in 1892, aM.A. in Mathematics and Physical Science in 1893, and aB.Sc. in Chemistry and Geology in 1894.[23][24]
When Rutherford began his studies at Cambridge, he was among the first 'aliens' (those without a Cambridge degree) allowed to do research at the university, and was additionally honoured to study underJ. J. Thomson.[2]
With Thomson's encouragement, Rutherford detected radio waves at 0.5 miles (800 m), and briefly held the world record for the distance over which electromagnetic waves could be detected, although when he presented his results at theBritish Association meeting in 1896, he discovered he had been outdone byGuglielmo Marconi, whose radio waves had sent a message across nearly 10 miles (16 km).[28]
Radioactivity
Again under Thomson's leadership, Rutherford worked on the conductive effects of X-rays on gases, which led to the discovery of theelectron, the results first presented by Thomson in 1897.[29][30] Hearing ofHenri Becquerel's experience withuranium, Rutherford started to explore itsradioactivity, discovering two types that differed from X-rays in their penetrating power. Continuing his research in Canada, in 1899 he coined the terms "alpha ray" and "beta ray" to describe these two distinct types ofradiation.[31]
In 1898, Rutherford accepted the Macdonald Chair of Physics atMcGill University in Montreal, Canada, on Thomson's recommendation.[32] From 1900 to 1903, he was joined at McGill by the young chemistFrederick Soddy (Nobel Prize in Chemistry, 1921) for whom he set the problem of identifying thenoble gas emitted by the radioactive elementthorium, a substance which was itself radioactive and would coat other substances. Once he had eliminated all the normal chemical reactions, Soddy suggested that it must be one of the inert gases, which they namedthoron. This substance was later found to be220Rn, an isotope of radon.[33][23] They also found another substance they called Thorium X, later identified as224Rn, and continued to find traces of helium. They also worked with samples of "Uranium X" (protactinium), fromWilliam Crookes, andradium, fromMarie Curie. Rutherford further investigated thoron in conjunction withR.B. Owens and found that a sample of radioactive material of any size invariably took the same amount of time for half the sample to decay (in this case, 111⁄2 minutes), a phenomenon for which he coined the term "half-life".[33] Rutherford and Soddy published their paper "Law of Radioactive Change" to account for all their experiments. Until then, atoms were assumed to be the indestructible basis of all matter; and although Curie had suggested that radioactivity was an atomic phenomenon, the idea of the atoms of radioactive substances breaking up was a radically new idea. Rutherford and Soddy demonstrated that radioactivity involved the spontaneous disintegration of atoms into other, as yet, unidentified matter.[23]
In 1903, Rutherford considered a type of radiation, discovered (but not named) by French chemistPaul Villard in 1900, as an emission fromradium, and realised that this observation must represent something different from his own alpha and beta rays, due to its very much greater penetrating power. Rutherford therefore gave this third type of radiation the name ofgamma ray.[31] All three of Rutherford's terms are in standard use today – other types ofradioactive decay have since been discovered, but Rutherford's three types are among the most common. In 1904, Rutherford suggested that radioactivity provides a source of energy sufficient to explain the existence of the Sun for the many millions of years required for the slow biological evolution on Earth proposed by biologists such asCharles Darwin. The physicistLord Kelvin had argued earlier for a much younger Earth, based on the insufficiency of known energy sources, but Rutherford pointed out, at a lecture attended by Kelvin, that radioactivity could solve this problem.[34] In 1907, he returned to Britain to take theLangworthy Professorship at theVictoria University of Manchester.[35]
In Manchester, Rutherford continued his work with alpha radiation. In conjunction withHans Geiger, he developed zinc sulfidescintillation screens andionisation chambers to count alpha particles. By dividing the total charge accumulated on the screen by the number counted, Rutherford determined that the charge on the alpha particle was two.[36][37]: 61 In late 1907, Ernest Rutherford andThomas Royds allowed alphas to penetrate a very thin window into an evacuated tube. As theysparked the tube into discharge, the spectrum obtained from it changed, as the alphas accumulated in the tube. Eventually, the clear spectrum of helium gas appeared, proving that alphas were at least ionised helium atoms, and probably helium nuclei.[38] In 1910 Rutherford, with Geiger and mathematicianHarry Bateman published[39]their classic paper[40]: 94 describing the first analysis of the distribution in time of radioactive emission, a distribution now called thePoisson distribution.
In 1908, Rutherford was awarded theNobel Prize in Chemistry "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances."[41]
Top: Expected results:alpha particles passing through theplum pudding model of the atom undisturbed. Bottom: Observed results: a small portion of the particles were deflected, indicatinga small, concentrated charge. Diagram is not to scale; in reality the nucleus is vastly smaller than the electron shell.
Rutherford continued to make ground-breaking discoveries long after receiving the Nobel prize in 1908.[37]: 63 Under his direction in 1909,Hans Geiger andErnest Marsden performed theGeiger–Marsden experiment, which demonstrated the nuclear nature of atoms by measuring the deflection ofalpha particles passing through a thin gold foil.[42] Rutherford was inspired to ask Geiger and Marsden in this experiment to look for alpha particles with very high deflection angles, which was not expected according to any theory of matter at that time.[43][44] Such deflection angles, although rare, were found. Reflecting on these results in one of his last lectures, Rutherford was quoted as saying: "It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you."[45] It was Rutherford's interpretation of this data that led him to propose thenucleus, a very small,charged region containing much of the atom's mass.[46]
In 1912, Rutherford was joined byNiels Bohr (who postulated that electrons moved in specific orbits about the compact nucleus). Bohr adapted Rutherford's nuclear structure to be consistent withMax Planck's quantum hypothesis. The resultingBohr model was the basis forquantum mechanical atomic physics of Heisenberg which remains valid today.[23]
Piezoelectricity
During World War I, Rutherford worked on a top-secret project to solve the practical problems of submarine detection. Both Rutherford andPaul Langevin suggested the use ofpiezoelectricity, and Rutherford successfully developed a device which measured its output. The use of piezoelectricity then became essential to the development ofultrasound as it is known today. The claim that Rutherford developedsonar, however, is a misconception, as subaquatic detection technologies utilise Langevin'stransducer.[47][48]
Discovery of the proton
Together withH.G. Moseley, Rutherford developed theatomic numbering system in 1913. Rutherford and Moseley's experiments usedcathode rays to bombard various elements with streams of electrons and observed that each element responded in a consistent and distinct manner. Their research was the first to assert that each element could be defined by the properties of its inner structures – an observation that later led to the discovery of theatomic nucleus.[23] This research led Rutherford to theorise that the hydrogen atom (at the time the least massive entity known to bear a positive charge) was a sort of "positive electron" – a component of every atomic element.[49][50]
It was not until 1919 that Rutherford expanded upon his theory of the "positive electron" with a series of experiments beginning shortly before the end of his time at Manchester. He found that nitrogen, and other light elements, ejected a proton, which he called a "hydrogen atom," when hit with α (alpha) particles.[23] In particular, he showed that particles ejected by alpha particles colliding with hydrogen have unit charge and 1/4 the momentum of alpha particles.[51]
Rutherford returned to the Cavendish Laboratory in 1919, succeeding J. J. Thomson asCavendish Professor, a position he held until his death in 1937.[52] During his tenure, Nobel prizes were awarded toJames Chadwick for discovering the neutron (in 1932),John Cockcroft andErnest Walton for an experiment that was to be known as "splitting the atom" using aparticle accelerator, andEdward Appleton for demonstrating the existence of theionosphere.
Development of proton and neutron theory
In 1919–1920, Rutherford continued his research on the "hydrogen atom" to confirm that alpha particles break down nitrogen nuclei and to affirm the nature of the products. This result showed Rutherford that hydrogen nuclei were a part of nitrogen nuclei (and by inference, probably other nuclei as well). Such a construction had been suspected for many years, on the basis of atomic weights that were integral multiples of that of hydrogen; seeProut's hypothesis. Hydrogen was known to be the lightest element, and its nuclei presumably the lightest nuclei. Now, because of all these considerations, Rutherford decided that a hydrogen nucleus was possibly a fundamental building block of all nuclei, and also possibly a new fundamental particle as well, since nothing was known to be lighter than that nucleus. Thus, confirming and extending the work ofWilhelm Wien, who in 1898 discovered the proton in streams ofionised gas,[53] in 1920 Rutherford postulated the hydrogen nucleus to be a new particle, which he dubbed theproton.[54]
In 1921, while working with Niels Bohr, Rutherford theorised about the existence ofneutrons, (which he had christened in his 1920Bakerian Lecture), which could somehow compensate for the repelling effect of the positive charges ofprotons by causing an attractivenuclear force and thus keep the nuclei from flying apart, due to the repulsion between protons. The only alternative to neutrons was the existence of "nuclear electrons", which would counteract some of the proton charges in the nucleus, since by then it was known that nuclei had about twice the mass that could be accounted for if they were simply assembled from hydrogen nuclei (protons). But how these nuclear electrons could be trapped in the nucleus, was a mystery.
In 1932, Rutherford's theory ofneutrons was proved by his associateJames Chadwick, who recognised neutrons immediately when they were produced by other scientists and later himself, in bombarding beryllium with alpha particles. In 1935, Chadwick was awarded the Nobel Prize in Physics for this discovery.[55]
Induced nuclear reaction and probing the nucleus
In Rutherford's four-part article on the "Collision of α-particles with light atoms" he reported two additional fundamental and far reaching discoveries.[37]: 237 First, he showed that at high angles the scattering of alpha particles from hydrogen differed from the theoretical results he himself published in 1911. These were the first results to probe the interactions that hold a nucleus together. Second, he showed that α-particles colliding with nitrogen nuclei would react rather than simply bounce off. One product of the reaction was the proton; the other product was shown byPatrick Blackett, Rutherford's colleague and former student, to be oxygen:
14N + α →17O + p.
Rutherford therefore recognised "that the nucleus may increase rather than diminish in mass as the result of collisions in which the proton is expelled".[56]Blackett was awarded the Nobel prize in 1948 for his work in perfecting the high-speed cloud chamber apparatus used to make that discovery and many others.[57]
Personal life and death
In the late 1880s Rutherford made his grandmother a wooden potato masher, which is now in the collection of theRoyal Society.[58][59]
In 1900, atSt Paul's Anglican Church, Papanui inChristchurch, Rutherford married Mary Georgina Newton (1876–1954),[60] to whom he had been engaged before leaving New Zealand.[61][62] They had one daughter, Eileen Mary (1901–1930); she married the physicistRalph Fowler, and died during the birth of her fourth child. Rutherford's hobbies includedgolf andmotoring.[23]
For some time before his death, Rutherford had a smallhernia, which he neglected to have repaired, and it eventually became strangulated, rendering him violently ill. He had an emergency operation in London, but died in Cambridge four days later, on 19 October 1937, at the age of 66, of what physicians termed "intestinal paralysis."[63] After cremation atGolders Green Crematorium,[63] he was given the high honour of burial inWestminster Abbey, nearIsaac Newton,Charles Darwin, and other illustrious British scientists.[23][64]
"For his researches on radioactivity, particularly for his discovery of the existence and properties of the gaseous emanations from radioactive bodies"
At the opening session of the 1938Indian Science Congress, which Rutherford had been expected to preside over before his death, astrophysicistJames Jeans spoke in his place and deemed him "one of the greatest scientists of all time", saying:
In his flair for the right line of approach to a problem, as well as in the simple directness of his methods of attack, [Rutherford] often reminds us of Faraday, but he had two great advantages which Faraday did not possess, first, exuberant bodily health and energy, and second, the opportunity and capacity to direct a band of enthusiastic co-workers. Great though Faraday's output of work was, it seems to me that to match Rutherford's work in quantity as well as in quality, we must go back to Newton. In some respects he was more fortunate than Newton. Rutherford was ever the happy warrior – happy in his work, happy in its outcome, and happy in its human contacts.[79]
Nuclear physics
Rutherford is known as "the father of nuclear physics" because his research, and work done under him as laboratory director, established the nuclear structure of the atom and the essential nature of radioactive decay as a nuclear process.[8][80][29]Patrick Blackett, a research fellow working under Rutherford, using natural alpha particles, demonstratedinducednuclear transmutation. Later, Rutherford's team, using protons from an accelerator, demonstratedartificially-induced nuclear reactions and transmutation.[81]
Rutherford died too early to seeLeó Szilárd's idea of controllednuclear chain reactions come into being. However, a speech of Rutherford's about his artificially-induced transmutation in lithium, printed in the 12 September 1933 issue ofThe Times, was reported by Szilárd to have been his inspiration for thinking of the possibility of a controlled energy-producingnuclear chain reaction.[82]
Rutherford's speech touched on the 1932 work of his studentsJohn Cockcroft andErnest Walton in "splitting" lithium into alpha particles by bombardment with protons from a particle accelerator they had constructed. Rutherford realised that the energy released from the split lithium atoms was enormous, but he also realised that the energy needed for the accelerator, and its essential inefficiency in splitting atoms in this fashion, made the project an impossibility as a practical source of energy (accelerator-induced fission of light elements remains too inefficient to be used in this way, even today). Rutherford's speech in part, read:
We might in these processes obtain very much more energy than the proton supplied, but on the average we could not expect to obtain energy in this way. It was a very poor and inefficient way of producing energy, and anyone who looked for a source of power in the transformation of the atoms was talking moonshine. But the subject was scientifically interesting because it gave insight into the atoms.[83][84]
The elementrutherfordium, Rf, Z=104, was named in honour of Rutherford in 1997.[85]
Ernest Rutherford (1938)."Forty Years of Physics". In Needham, Joseph; Pagel, Walter (eds.).Background to Modern Science: Ten Lectures at Cambridge arranged by the History of Science Committee 1936.Cambridge University Press.
^"University of the Punjab - Science".pu.edu.pk.Archived from the original on 2 October 2023. Retrieved15 September 2023.The expedition included Professor James Martin Benade (Professor of Physics at Forman Christian College Lahore) and Dr. Nazir Ahmad (a PhD student of Ernest Rutherford at Cambridge who later on became the First Chairman of Pakistan Atomic Energy Commission in 1956).
^Grodzins, Lee (February 1994)."Obituaries: Zhang Wen-Yu".Physics Today.47 (2): 116.doi:10.1063/1.2808417.Zhang studied under Ernest Rutherford in the mid-1930s, receiving his degree from Cambridge University in 1938.
^Zhang Wenyu (张文裕) (28 March 2018).高能实验物理学家张文裕：回忆导师卢瑟福生命中的最后两年.thepaper.com (in Chinese).Archived from the original on 12 August 2021. Retrieved12 August 2021.
^ab"Ernest Rutherford".Environmental Health and Safety Office of Research Regulatory Support. Michigan State University.Archived from the original on 22 June 2023. Retrieved23 June 2023.
^Rutherford, Ernest (1914)."The structure of the atom"(PDF).Philosophical Magazine.27:488–498.Archived(PDF) from the original on 13 June 2023. Retrieved13 June 2023.
^Whittaker, Edmund (1989).A History of the Theories of Aether and Electricity. Vol. 2. Courier Dover Publications. p. 87.ISBN0-486-26126-3.
^Orme Masson (1921)."The Constitution of Atoms".The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science.41 (242):281–285.doi:10.1080/14786442108636219. Footnote by Ernest Rutherford: 'At the time of writing this paper in Australia, Professor Orme Masson was not aware that the name "proton" had already been suggested as a suitable name for the unit of mass nearly 1, in terms of oxygen 16, that appears to enter into the nuclear structure of atoms. The question of a suitable name for this unit was discussed at an informal meeting of a number of members of Section A of the British Association at Cardiff this year. The name "baron" suggested by Professor Masson was mentioned, but was considered unsuitable on account of the existing variety of meanings. Finally the name "proton" met with general approval, particularly as it suggests the original term "protyle " given by Prout in his well-known hypothesis that all atoms are built up of hydrogen. The need of a special name for the nuclear unit of mass 1 was drawn attention to by Sir Oliver Lodge at the Sectional meeting, and the writer then suggested the name "proton."'
^"James Chadwick – Facts".The Nobel Prize. Nobel Prize Outreach AB.Archived from the original on 4 October 2019. Retrieved16 June 2023.
^Freemantle, Michael (2003)."ACS Article on Rutherfordium".Chemical & Engineering News. American Chemical Society.Archived from the original on 28 March 2008. Retrieved2 April 2008.
Ernest Rutherford on Nobelprize.org including the Nobel Lecture, 11 December 1908The Chemical Nature of the Alpha Particles from Radioactive Substances
