Ernest Rutherford

From Wikipedia, the free encyclopedia

The Right Honourable The Lord Rutherford of Nelson FRS OM
Born	(1871-08-30)30 August 1871 Brightwater, Tasman District, New Zealand
Died	19 October 1937(1937-10-19) (aged 66) Cambridge, England, UK
Residence	New Zealand, United Kingdom
Citizenship	New Zealand, United Kingdom
Nationality	British and New Zealander
Fields	Physics and Chemistry
Institutions	McGill University University of Manchester University of Cambridge
Alma mater	University of Canterbury University of Cambridge
Academic advisors	Alexander Bickerton J. J. Thomson
Doctoral students	Nazir Ahmed Norman Alexander Edward Victor Appleton Robert William Boyle James Chadwick Rafi Muhammad Chaudhry Norman Feather Alexander MacAulay Cecil Powell Henry DeWolf Smyth Ernest Walton C. E. Wynn-Williams Yulii Borisovich Khariton
Other notable students	Edward Andrade Edward Victor Appleton Patrick Blackett Niels Bohr Bertram Boltwood Harriet Brooks Teddy Bullard John Cockcroft Charles Galton Darwin Charles Drummond Ellis Kazimierz Fajans Hans Geiger Otto Hahn Douglas Hartree Pyotr Kapitsa Daulat Singh Kothari George Laurence Iven Mackay Ernest Marsden Mark Oliphant Thomas Royds Frederick Soddy
Known for	Father of nuclear physics Rutherford model Rutherford scattering Rutherford backscattering spectroscopy Discovery of proton Rutherford (unit) Coining the term 'artificial disintegration'
Influenced	Henry Moseley Hans Geiger Albert Beaumont Wood
Notable awards	Rumford Medal (1904) Nobel Prize in Chemistry (1908) Barnard Medal (1910) Elliott Cresson Medal (1910) Matteucci Medal (1913) Copley Medal (1922) Franklin Medal (1924) Albert Medal (1928) Faraday Medal (1930)
Signature

Ernest Rutherford, 1st Baron Rutherford of Nelson, OM FRS^[1] (30 August 1871 – 19 October 1937) was a New Zealand-born British physicist who became known as the father of nuclear physics.^[2] Encyclopædia Britannica considers him to be the greatest experimentalist since Michael Faraday (1791–1867).^[2]

In early work he discovered the concept of radioactive half-life, proved that radioactivity involved the transmutation of one chemical element to another, and also differentiated and named alpha and beta radiation.^[3] This work was done at McGill University in Canada. It is the basis for the Nobel Prize in Chemistry he was awarded in 1908 "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances",^[4] for which he remains the first Canadian and Oceanian Nobel laureate, and the only laureate born in the South Island.

Rutherford moved in 1907 to the Victoria University of Manchester (today University of Manchester) in the UK, where he and Thomas Royds proved that alpha radiation is helium nuclei.^[5][6] Rutherford performed his most famous work after he became a Nobel laureate.^[4] In 1911, although he could not prove that it was positive or negative,^[7] he theorized that atoms have their charge concentrated in a very small nucleus,^[8] and thereby pioneered the Rutherford model of the atom, through his discovery and interpretation of Rutherford scattering in his gold foil experiment. He is widely credited with first "splitting the atom" in 1917 in a nuclear reaction between nitrogen and alpha particles, in which he also discovered (and named) the proton.^[9]

Rutherford became Director of the Cavendish Laboratory at Cambridge University in 1919. Under his leadership the neutron was discovered by James Chadwick in 1932 and in the same year the first experiment to split the nucleus in a fully controlled manner, performed by students working under his direction, John Cockcroft and Ernest Walton. After his death in 1937, he was honoured by being interred with the greatest scientists of the United Kingdom, near Sir Isaac Newton's tomb in Westminster Abbey. The chemical element rutherfordium (element 104) was named after him in 1997.

Biography

Early life and education

Rutherford aged 21

Ernest Rutherford was the son of James Rutherford, a farmer, and his wife Martha Thompson, originally from Hornchurch, Essex, England.^[10] James had emigrated to New Zealand from Perth, Scotland, "to raise a little flax and a lot of children". Ernest was born at Brightwater, near Nelson, New Zealand. His first name was mistakenly spelled 'Earnest' when his birth was registered.^[11]

He studied at Havelock School and then Nelson College and won a scholarship to study at Canterbury College, University of New Zealand where he participated in the debating society and played rugby.^[12] After gaining his BA, MA and BSc, and doing two years of research during which he invented a new form of radio receiver, in 1895 Rutherford was awarded an 1851 Research Fellowship from the Royal Commission for the Exhibition of 1851,^[13] to travel to England for postgraduate study at the Cavendish Laboratory, University of Cambridge.^[14] He was among the first of the 'aliens' (those without a Cambridge degree) allowed to do research at the university, under the inspiring leadership of J. J. Thomson, and the newcomers aroused jealousies from the more conservative members of the Cavendish fraternity. With Thomson's encouragement, he managed to detect radio waves at half a mile and briefly held the world record for the distance over which electromagnetic waves could be detected, though when he presented his results at the British Association meeting in 1896, he discovered he had been outdone by another lecturer, by the name of Marconi.

In 1898 Thomson recommended Rutherford for a position at McGill University in Montreal, Canada. He was to replace Hugh Longbourne Callendar who held the chair of Macdonald Professor of physics and was coming to Cambridge.^[15] Rutherford was accepted, which meant that in 1900 he could marry Mary Georgina Newton (1876–1945) to whom he had become engaged before leaving New Zealand; they had one daughter, Eileen Mary (1901–1930), who married Ralph Fowler. In 1900 he gained a DSc from the University of New Zealand. In 1907 Rutherford returned to Britain to take the chair of physics at the University of Manchester.

Later years and honours

He was knighted in 1914. During World War I, he worked on a top secret project to solve the practical problems of submarine detection by sonar.^[16] In 1916 he was awarded the Hector Memorial Medal. In 1919 he returned to the Cavendish succeeding J. J. Thomson as the Cavendish professor and Director. Under him, Nobel Prizes were awarded to James Chadwick for discovering the neutron (in 1932), John Cockcroft and Ernest Walton for an experiment which was to be known as splitting the atom using a particle accelerator, and Edward Appleton for demonstrating the existence of the ionosphere. Between 1925 and 1930 he served as President of the Royal Society, and later as president of the Academic Assistance Council which helped almost 1,000 university refugees from Germany.^[2] He was admitted to the Order of Merit in 1925 and raised to the peerage as Baron Rutherford of Nelson, in 1931,^[17] a title that became extinct upon his unexpected death in 1937.

For some time beforehand, Rutherford had a small hernia, which he had neglected to have fixed, and it became strangulated, causing him to be violently ill. Despite an emergency operation in London, he died four days afterwards of what physicians termed "intestinal paralysis", at Cambridge.^[18] After cremation at Golders Green Crematorium,^[18] he was given the high honour of burial in Westminster Abbey, near Isaac Newton and other illustrious British scientists.^[19]

Scientific research

Rutherford at McGill University in 1905

At Cambridge, Rutherford started to work with J. J. Thomson on the conductive effects of X-rays on gases, work which led to the discovery of the electron which Thomson presented to the world in 1897. Hearing of Becquerel's experience with uranium, Rutherford started to explore its radioactivity, discovering two types that differed from X-rays in their penetrating power. Continuing his research in Canada, he coined the terms alpha ray and beta ray in 1899 to describe the two distinct types of radiation. He then discovered that thorium gave off a gas which produced an emanation which was itself radioactive and would coat other substances. He found that a sample of this radioactive material of any size invariably took the same amount of time for half the sample to decay – its "half-life" (11½ minutes in this case).

From 1900 to 1903, he was joined at McGill by the young chemist Frederick Soddy (Nobel Prize in Chemistry, 1921) for whom he set the problem of identifying the thorium emanations. Once he had eliminated all the normal chemical reactions, Soddy suggested that it must be one of the inert gases, which they named thoron (later found to be an isotope of radon). They also found another type of thorium they called Thorium X, and kept on finding traces of helium. They also worked with samples of "Uranium X" from William Crookes and radium from Marie Curie.

In 1902, they produced a "Theory of Atomic Disintegration" to account for all their experiments. Up till then atoms were assumed to be the indestructable 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 types of atoms (one element spontaneously being changed to another).

In 1903, Rutherford considered a type of radiation discovered (but not named) by French chemist Paul Villard in 1900, as an emission from radium, 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 of gamma ray. All three of Rutherford's terms are in standard use today – other types of radioactive decay have since been discovered, but Rutherford's three types are among the most common.

In Manchester, he continued to work with alpha radiation. In conjunction with Hans Geiger, he developed zinc sulfide scintillation screens and ionisation chambers to count alphas. By dividing the total charge they produced by the number counted, Rutherford decided that the charge on the alpha was two. In late 1907, Ernest Rutherford and Thomas Royds allowed alphas to penetrate a very thin window into an evacuated tube. As they sparked 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.

Gold foil experiment

Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed.
Bottom: Observed results: a small portion of the particles were deflected, indicating a small, concentrated charge. Note that the image is not to scale; in reality the nucleus is vastly smaller than the electron shell.

Rutherford performed his most famous work after receiving the Nobel prize in 1908. Along with Hans Geiger and Ernest Marsden in 1909, he carried out the Geiger–Marsden experiment, which demonstrated the nuclear nature of atoms by deflecting alpha particles passing through a thin gold foil. Rutherford was inspired to ask Geiger and Marsden in this experiment to look for alpha particles with very high deflection angles, of a type not expected from any theory of matter at that time. Such deflections, though rare, were found, and proved to be a smooth but high-order function of the deflection angle. It was Rutherford's interpretation of this data that led him to formulate the Rutherford model of the atom in 1911 – that a very small charged ^[7] nucleus, containing much of the atom's mass, was orbited by low-mass electrons.

Before leaving Manchester in 1919 to take over the Cavendish laboratory in Cambridge, Rutherford became, in 1919, the first person to deliberately transmute one element into another.^[4] In this experiment, he had discovered peculiar radiations when alphas were projected into air, and narrowed the effect down to the nitrogen, not the oxygen in the air. Using pure nitrogen, Rutherford used alpha radiation to convert nitrogen into oxygen through the nuclear reaction ¹⁴N + α → ¹⁷O + proton. The proton was not then known. In the products of this reaction Rutherford simply identified hydrogen nuclei, by their similarity to the particle radiation from earlier experiments in which he had bombarded hydrogen gas with alpha particles to knock hydrogen nuclei out of hydrogen atoms. 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 which were whole numbers of that of hydrogen; see Prout'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 from the nucleus that was lighter. Thus, Rutherford postulated hydrogen nuclei to be a new particle in 1920, which he dubbed the proton.

In 1921, while working with Niels Bohr (who postulated that electrons moved in specific orbits), Rutherford theorized about the existence of neutrons, (which he had christened in his 1920 Bakerian Lecture), which could somehow compensate for the repelling effect of the positive charges of protons by causing an attractive nuclear force and thus keep the nuclei from flying apart from 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.

Rutherford's theory of neutrons was proved in 1932 by his associate James Chadwick, who recognized 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.

Legacy

A plaque commemorating Rutherford's presence at the Victoria University, Manchester

Nuclear physics

Rutherford's 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. Rutherford's team, using natural alpha particles, demonstrated induced nuclear transmutation, and later, using protons from an accelerator, demonstrated artificially-induced nuclear reactions and transmutation. He is known as the father of nuclear physics. Rutherford died too early to see Leó Szilárd's idea of controlled nuclear chain reactions come into being. However, a speech of Rutherford's about his artificially-induced transmutation in lithium, printed in 12 September 1933 London paper The Times, was reported by Szilárd to have been his inspiration for thinking of the possibility of a controlled energy-producing nuclear chain reaction. Szilard had this idea while walking in London, on the same day.

Rutherford's speech touched on the 1932 work of his students John Cockcroft and Ernest Walton in "splitting" lithium into alpha particles by bombardment with protons from a particle accelerator they had constructed. Rutherford realized that the energy released from the split lithium atoms was enormous, but he also realized 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.^[20]

Items named in honour of Rutherford's life and work

A statue of a young Ernest Rutherford at his memorial in Brightwater, New Zealand.

Scientific discoveries

• The element rutherfordium, Rf, Z=104. (1997)^[21]
• The rutherford (Rd), an obsolete unit of radioactivity equivalent to one megabecquerel.

Institutions

• Rutherford Appleton Laboratory, a scientific research laboratory near Didcot, Oxfordshire.
• Rutherford College, Auckland, a school in Auckland, New Zealand
• Rutherford College, Kent, a college at the University of Kent in Canterbury, England
• Rutherford Institute for Innovation at the University of Cambridge
• Rutherford Intermediate School, Wanganui, New Zealand
• Rutherford Hall, a hall of residence at Loughborough University

Awards

• Rutherford Medal, the highest science medal awarded by the Royal Society of New Zealand
• Rutherford Award at Thomas Carr College for excellence in Victorian Certificate of Education chemistry, Australia.
• Rutherford Memorial Medal is an award for research in the fields of physics and chemistry by the Royal Society of Canada.
• Rutherford Medal and Prize is awarded once every two years by the Institute of Physics for "distinguished research in nuclear physics or nuclear technology".
• Rutherford Memorial Lecture is an international lecture tour under the auspices of the Royal Society created under the Rutherford Memorial Scheme in 1952.

Buildings

• Rutherford House, a boarding house at Nelson College^[22]
• Rutherford Hotel, Nelson's largest hotel, which incorporates the Rutherford Cafe and Bar
• The physics and chemistry building at the University of Canterbury, New Zealand
• Rochester and Rutherford Hall at the University of Canterbury, New Zealand
• Rutherford House, the primary building of Victoria University of Wellington's Pipitea Campus, originally the headquarters of the New Zealand Electricity Department, in Wellington, New Zealand.
• Rutherford building at Bedford Modern School.
• A building of the modern Cavendish Laboratory at the University of Cambridge
• The Ernest Rutherford Physics Building at McGill University, Montreal^[23]
• The Coupland Building at the University of Manchester, where Rutherford worked, was renamed "The Rutherford Building" in 2006.
• The Rutherford lecture theatre in the Schuster Laboratory at the University of Manchester

Major streets

• Lord Rutherford Road (the location of his birthplace in Brightwater, New Zealand)
• Rutherford Street, a major thoroughfare in central Nelson, New Zealand
• Rutherford Close, a residential street in Abingdon, Oxfordshire
• Rutherford Road in the biotechnology district of Carlsbad, California
• Rutherford Road, commercial/residential street in Vaughan, Ontario, Canada

Other

• Rutherford Park, a sports ground in Nelson, New Zealand
• The Rutherford Memorial at the site of his birth in Brightwater, New Zealand
• His image is on the obverse of the New Zealand one hundred-dollar note (since 1992).
• The Rutherford Foundation, a charitable trust set up by the Royal Society of New Zealand to support research in science and technology.^[24]
• Rutherford House, at Macleans College, Auckland, New Zealand
• Rutherford House, at Hillcrest High School, Hamilton, New Zealand
• Rutherford House, at Rotorua Intermediate School, Rotorua, New Zealand
• Rutherford House, at Rangiora High School
• The crater Rutherford on the Moon, and the crater Rutherford on the planet Mars (planet)
• Ernest Rutherford was the subject of a play by Stuart Hoar.
• On the side of the Mond Laboratory on the site of the original Cavendish Laboratory in Cambridge, there is an engraving in Rutherford's memory in the form of a crocodile, this being the nickname given to him by its commissioner, his colleague Peter Kapitza.

Incidences of cancer at Rutherford's former laboratory

The Coupland Building at Manchester University, at which Rutherford conducted many of his experiments, has been the subject of a cancer cluster investigation.^{[citation needed]} There has been a statistically high incidence of pancreatic cancer, brain cancer, and motor neuron disease occurring in and around Rutherford's former laboratories and, since 1984, a total of six workers have been stricken with these ailments. In 2009, an independent commission concluded that the very slightly elevated levels of various radiation related to Rutherford's experiments decades earlier are not the likely cause of such cancers and ruled the illnesses a coincidence.^[25]

Publications

• Radio-activity (1904), 2nd ed. (1905), ISBN 978-1-60355-058-1
• Radioactive Transformations (1906), ISBN 978-1-60355-054-3
• Radioactive Substances and their Radiations (1913)^[26]
• The Electrical Structure of Matter (1926)
• The Artificial Transmutation of the Elements (1933)
• The Newer Alchemy (1937)

Arms

Arms of Ernest Rutherford

Notes The arms of Ernest Rutherford consist of:[27][28] Crest A baron's coronet. On a helm wreathed of the Colors, a kiwi Proper. Escutcheon Per saltire arched Gules and Or, two inescutcheons voided of the first in fess, within each a martlet Sable. Supporters Dexter, Hermes Trismegistus (mythological patron of knowledge and alchemists). Sinister, a Māori warrior. Motto Primordia Quaerere Rerum ("To seek the first principles of things." Lucretius.)

Max Plan ck

From Wikipedia, the free encyclopedia

Max Planck
Planck in 1933
Born	Max Karl Ernst Ludwig Planck (1858-04-23)April 23, 1858 Kiel, Duchy of Holstein
Died	October 4, 1947(1947-10-04) (aged 89) Göttingen, Lower Saxony, Germany
Nationality	German
Fields	Physics
Institutions	University of Kiel University of Berlin University of Göttingen Kaiser Wilhelm Society
Alma mater	Ludwig Maximilian University of Munich
Doctoral advisor	Alexander von Brill
Doctoral students	Erich Kretschmann Gustav Ludwig Hertz Julius Edgar Lilienfeld Max Abraham Max von Laue Moritz Schlick Walter Schottky Walther Bothe Walther Meissner
Other notable students	Lise Meitner
Known for	Planck constant Planck postulate Planck's law of black body radiation
Notable awards	Nobel Prize in Physics (1918) Lorentz Medal (1927) Copley Medal (1929) Max Planck Medal (1929) Goethe Prize (1945)
Spouse	Marie Merck (1887–1909) Marga von Hösslin (1911–1947)
Signature
Notes His son Erwin Planck was executed in 1945 by the Gestapo for his part in the assassination attempt on Adolf Hitler July 20 plot.

Max Karl Ernst Ludwig Planck, FRS^[1] (/plɑːŋk/;^[2] German: [plaŋk]; April 23, 1858 – October 4, 1947) was a German theoretical physicist who originated quantum theory, which won him the Nobel Prize in Physics in 1918.^[3]
Planck made many contributions to theoretical physics, but his fame as a physicist rests primarily on his role as an originator of the quantum theory. However, his name is also known on a broader academic basis, through the renaming in 1948 of the German scientific institution, the Kaiser Wilhelm Society (of which he was twice president), as the Max Planck Society (MPS). The MPS now includes 83 institutions representing a wide range of scientific directions.

Max Planck's quantum theory revolutionized human understanding of atomic and subatomic processes, just as Albert Einstein’s theory of relativity revolutionized the understanding of space and time.

Early life and career

Planck came from a traditional, intellectual family. His paternal great-grandfather and grandfather were both theology professors in Göttingen; his father was a law professor in Kiel and Munich.

Max Planck's signature at ten years of age.

Planck was born in Kiel, Holstein, to Johann Julius Wilhelm Planck and his second wife, Emma Patzig. He was baptised with the name of Karl Ernst Ludwig Marx Planck; of his given names, Marx (a now obsolete variant of Markus or maybe simply an error for Max, which is actually short for Maximilian) was indicated as the primary name.^[4] However, by the age of ten he signed with the name Max and used this for the rest of his life.^[5]

He was the 6th child in the family, though two of his siblings were from his father's first marriage. Among his earliest memories was the marching of Prussian and Austrian troops into Kiel during the Second Schleswig War in 1864. In 1867 the family moved to Munich, and Planck enrolled in the Maximilians gymnasium school, where he came under the tutelage of Hermann Müller, a mathematician who took an interest in the youth, and taught him astronomy and mechanics as well as mathematics. It was from Müller that Planck first learned the principle of conservation of energy. Planck graduated early, at age 17.^[6] This is how Planck first came in contact with the field of physics.

Planck was gifted when it came to music. He took singing lessons and played piano, organ and cello, and composed songs and operas. However, instead of music he chose to study physics.

Planck as a young man, 1878

The Munich physics professor Philipp von Jolly advised Planck against going into physics, saying, "in this field, almost everything is already discovered, and all that remains is to fill a few holes."^[7] Planck replied that he did not wish to discover new things, but only to understand the known fundamentals of the field, and so began his studies in 1874 at the University of Munich. Under Jolly's supervision, Planck performed the only experiments of his scientific career, studying the diffusion of hydrogen through heated platinum, but transferred to theoretical physics.

In 1877 he went to Berlin for a year of study with physicists Hermann von Helmholtz and Gustav Kirchhoff and mathematician Karl Weierstrass. He wrote that Helmholtz was never quite prepared, spoke slowly, miscalculated endlessly, and bored his listeners, while Kirchhoff spoke in carefully prepared lectures which were dry and monotonous. He soon became close friends with Helmholtz. While there he undertook a program of mostly self-study of Clausius's writings, which led him to choose heat theory as his field.

In October 1878 Planck passed his qualifying exams and in February 1879 defended his dissertation, Über den zweiten Hauptsatz der mechanischen Wärmetheorie (On the second law of thermodynamics). He briefly taught mathematics and physics at his former school in Munich.

In June 1880, he presented his habilitation thesis, Gleichgewichtszustände isotroper Körper in verschiedenen Temperaturen (Equilibrium states of isotropic bodies at different temperatures).

Academic career

With the completion of his habilitation thesis, Planck became an unpaid private lecturer in Munich, waiting until he was offered an academic position. Although he was initially ignored by the academic community, he furthered his work on the field of heat theory and discovered one after another the same thermodynamical formalism as Gibbs without realizing it. Clausius's ideas on entropy occupied a central role in his work.

In April 1885 the University of Kiel appointed Planck as associate professor of theoretical physics. Further work on entropy and its treatment, especially as applied in physical chemistry, followed. He published his Treatise on Thermodynamics in 1897.^[8] He proposed a thermodynamic basis for Svante Arrhenius's theory of electrolytic dissociation.

Within four years he was named the successor to Kirchhoff's position at the University of Berlin — presumably thanks to Helmholtz's intercession — and by 1892 became a full professor. In 1907 Planck was offered Boltzmann's position in Vienna, but turned it down to stay in Berlin. During 1909, as University of Berlin professor, he was invited to become the Ernest Kempton Adams Lecturer in Theoretical Physics at Columbia University in New York City. A series of his lectures were translated and co-published by Columbia University professor A. P. Wills.^[9] He retired from Berlin on January 10, 1926, and was succeeded by Erwin Schrödinger.

Family

In March 1887 Planck married Marie Merck (1861–1909), sister of a school fellow, and moved with her into a sublet apartment in Kiel. They had four children: Karl (1888–1916), the twins Emma (1889–1919) and Grete (1889–1917), and Erwin (1893–1945).

After the apartment in Berlin, the Planck family lived in a villa in Berlin-Grunewald, Wangenheimstrasse 21. Several other professors of Berlin University lived nearby, among them theologian Adolf von Harnack, who became a close friend of Planck. Soon the Planck home became a social and cultural centre. Numerous well-known scientists, such as Albert Einstein, Otto Hahn and Lise Meitner were frequent visitors. The tradition of jointly performing music had already been established in the home of Helmholtz.

After several happy years, in July 1909 Marie Planck died, possibly from tuberculosis. In March 1911 Planck married his second wife, Marga von Hoesslin (1882–1948); in December his fifth child Hermann was born.

During the First World War Planck's second son Erwin was taken prisoner by the French in 1914, while his oldest son Karl was killed in action at Verdun. Grete died in 1917 while giving birth to her first child. Her sister died the same way two years later, after having married Grete's widower. Both granddaughters survived and were named after their mothers. Planck endured these losses stoically.

In January 1945, Erwin, to whom he had been particularly close, was sentenced to death by the Nazi Volksgerichtshof because of his participation in the failed attempt to assassinate Hitler in July 1944. Erwin was executed on 23 January 1945.^[10]

• Wives: Marie Merck (m. 1887), Marga von Hoesslin (m. 1911)
• Children: Karl (1888–1916), twins Emma (1889–1919) and Grete (1889–1917), Erwin (1893–1945), Hermann (1911–1954)

Professor at Berlin University

In Berlin, Planck joined the local Physical Society. He later wrote about this time: "In those days I was essentially the only theoretical physicist there, whence things were not so easy for me, because I started mentioning entropy, but this was not quite fashionable, since it was regarded as a mathematical spook".^[11] Thanks to his initiative, the various local Physical Societies of Germany merged in 1898 to form the German Physical Society (Deutsche Physikalische Gesellschaft, DPG); from 1905 to 1909 Planck was the president.

Plaque at the Humboldt University of Berlin: "Max Planck, discoverer of the elementary quantum of action h, taught in this building from 1889 to 1928."

Planck started a six-semester course of lectures on theoretical physics, "dry, somewhat impersonal" according to Lise Meitner, "using no notes, never making mistakes, never faltering; the best lecturer I ever heard" according to an English participant, James R. Partington, who continues: "There were always many standing around the room. As the lecture-room was well heated and rather close, some of the listeners would from time to time drop to the floor, but this did not disturb the lecture". Planck did not establish an actual "school"; the number of his graduate students was only about 20, among them:

1897 Max Abraham (1875–1922)

1904 Moritz Schlick (1882–1936)

1906 Walther Meissner (1882–1974)

1906 Max von Laue (1879–1960)

1907 Fritz Reiche (1883–1960)

1912 Walter Schottky (1886–1976)

1914 Walther Bothe (1891–1957)

Black-body radiation

In 1894 Planck turned his attention to the problem of black-body radiation. He had been commissioned by electric companies to create maximum light from lightbulbs with minimum energy. The problem had been stated by Kirchhoff in 1859: "how does the intensity of the electromagnetic radiation emitted by a black body (a perfect absorber, also known as a cavity radiator) depend on the frequency of the radiation (i.e., the color of the light) and the temperature of the body?". The question had been explored experimentally, but no theoretical treatment agreed with experimental values. Wilhelm Wien proposed Wien's law, which correctly predicted the behaviour at high frequencies, but failed at low frequencies. The Rayleigh–Jeans law, another approach to the problem, created what was later known as the "ultraviolet catastrophe", but contrary to many textbooks this was not a motivation for Planck.^[12]

Planck's first proposed solution to the problem in 1899 followed from what Planck called the "principle of elementary disorder", which allowed him to derive Wien's law from a number of assumptions about the entropy of an ideal oscillator, creating what was referred-to as the Wien–Planck law. Soon it was found that experimental evidence did not confirm the new law at all, to Planck's frustration. Planck revised his approach, deriving the first version of the famous Planck black-body radiation law, which described the experimentally observed black-body spectrum well. It was first proposed in a meeting of the DPG on October 19, 1900 and published in 1901. This first derivation did not include energy quantisation, and did not use statistical mechanics, to which he held an aversion. In November 1900, Planck revised this first approach, relying on Boltzmann's statistical interpretation of the second law of thermodynamics as a way of gaining a more fundamental understanding of the principles behind his radiation law. As Planck was deeply suspicious of the philosophical and physical implications of such an interpretation of Boltzmann's approach, his recourse to them was, as he later put it, "an act of despair ... I was ready to sacrifice any of my previous convictions about physics."^[12]

The central assumption behind his new derivation, presented to the DPG on 14 December 1900, was the supposition, now known as the Planck postulate, that electromagnetic energy could be emitted only in quantized form, in other words, the energy could only be a multiple of an elementary unit , where is Planck's constant, also known as Planck's action quantum (introduced already in 1899), and (the Greek letter nu, not the Roman letter v) is the frequency of the radiation. Note that the elementary units of energy discussed here are represented by and not simply by . Physicists now call these quanta photons, and a photon of frequency will have its own specific and unique energy. The total energy at that frequency is then equal to multiplied by the number of photons at that frequency.

Planck in 1918, the year he received the Nobel Prize in Physics for his work on quantum theory

At first Planck considered that quantisation was only "a purely formal assumption ... actually I did not think much about it..."; nowadays this assumption, incompatible with classical physics, is regarded as the birth of quantum physics and the greatest intellectual accomplishment of Planck's career (Ludwig Boltzmann had been discussing in a theoretical paper in 1877 the possibility that the energy states of a physical system could be discrete). The discovery of Planck's constant enabled him to define a new universal set of physical units (such as the Planck length and the Planck mass), all based on fundamental physical constants upon which much of quantum theory is based. In recognition of Planck's fundamental contribution to a new branch of physics, he was awarded the Nobel Prize in Physics in 1918.^[13]

Subsequently, Planck tried to grasp the meaning of energy quanta, but to no avail. "My unavailing attempts to somehow reintegrate the action quantum into classical theory extended over several years and caused me much trouble." Even several years later, other physicists like Rayleigh, Jeans, and Lorentz set Planck's constant to zero in order to align with classical physics, but Planck knew well that this constant had a precise nonzero value. "I am unable to understand Jeans' stubbornness — he is an example of a theoretician as should never be existing, the same as Hegel was for philosophy. So much the worse for the facts if they don't fit."^[14]

Max Born wrote about Planck: "He was, by nature, a conservative mind; he had nothing of the revolutionary and was thoroughly skeptical about speculations. Yet his belief in the compelling force of logical reasoning from facts was so strong that he did not flinch from announcing the most revolutionary idea which ever has shaken physics."^[1]

Einstein and the theory of relativity

In 1905, the three epochal papers of the hitherto completely unknown Albert Einstein were published in the journal Annalen der Physik. Planck was among the few who immediately recognized the significance of the special theory of relativity. Thanks to his influence, this theory was soon widely accepted in Germany. Planck also contributed considerably to extend the special theory of relativity. For example, he recast the theory in terms of classical action.^[15]

Einstein's hypothesis of light quanta (photons), based on Philipp Lenard's 1902 discovery of the photoelectric effect, was initially rejected by Planck. He was unwilling to discard completely Maxwell's theory of electrodynamics. "The theory of light would be thrown back not by decades, but by centuries, into the age when Christian Huygens dared to fight against the mighty emission theory of Isaac Newton ..."^{[citation needed]}

In 1910, Einstein pointed out the anomalous behavior of specific heat at low temperatures as another example of a phenomenon which defies explanation by classical physics. Planck and Nernst, seeking to clarify the increasing number of contradictions, organized the First Solvay Conference (Brussels 1911). At this meeting Einstein was able to convince Planck.

Meanwhile, Planck had been appointed dean of Berlin University, whereby it was possible for him to call Einstein to Berlin and establish a new professorship for him (1914). Soon the two scientists became close friends and met frequently to play music together.

World War I

At the onset of the First World War Planck endorsed the general excitement of the public, writing that, "Besides much that is horrible, there is also much that is unexpectedly great and beautiful: the smooth solution of the most difficult domestic political problems by the unification of all parties (and) ... the extolling of everything good and noble."^[16][17]

Nonetheless, Planck refrained from the extremes of nationalism. In 1915, at a time when Italy was about to join the Allied Powers, he voted successfully for a scientific paper from Italy, which received a prize from the Prussian Academy of Sciences, where Planck was one of four permanent presidents.

Planck also signed the infamous "Manifesto of the 93 intellectuals", a pamphlet of polemic war propaganda (while Einstein retained a strictly pacifistic attitude which almost led to his imprisonment, being spared by his Swiss citizenship). But in 1915 Planck, after several meetings with Dutch physicist Lorentz, revoked parts of the Manifesto. Then in 1916 he signed a declaration against German annexationism.

Post War and Weimar Republic

In the turbulent post-war years, Planck, now the highest authority of German physics, issued the slogan "persevere and continue working" to his colleagues.

In October 1920 he and Fritz Haber established the Notgemeinschaft der Deutschen Wissenschaft (Emergency Organization of German Science), aimed at providing financial support for scientific research. A considerable portion of the moneys the organization would distribute were raised abroad.

Planck also held leading positions at Berlin University, the Prussian Academy of Sciences, the German Physical Society and the Kaiser Wilhelm Society (which in 1948 became the Max Planck Society). During this time economic conditions in Germany were such that he was hardly able to conduct research.

During the interwar period, Planck became a member of the Deutsche Volks-Partei (German People's Party), the party of Nobel Peace Prize laureate Gustav Stresemann, which aspired to liberal aims for domestic policy and rather revisionistic aims for international politics.

Planck disagreed with the introduction of universal suffrage and later expressed the view that the Nazi dictatorship resulted from "the ascent of the rule of the crowds".^[18]

Quantum mechanics

From left to right: W. Nernst, A. Einstein, M. Planck, R.A. Millikan and von Laue at a dinner given by von Laue in Berlin on 11 November 1931

At the end of the 1920s Bohr, Heisenberg and Pauli had worked out the Copenhagen interpretation of quantum mechanics, but it was rejected by Planck, and by Schrödinger, Laue, and Einstein as well. Planck expected that wave mechanics would soon render quantum theory—his own child—unnecessary. This was not to be the case, however. Further work only cemented quantum theory, even against his and Einstein's philosophical revulsions. Planck experienced the truth of his own earlier observation from his struggle with the older views in his younger years: "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."^[19]

Nazi dictatorship and the Second World War

When the Nazis seized power in 1933, Planck was 74. He witnessed many Jewish friends and colleagues expelled from their positions and humiliated, and hundreds of scientists emigrated from Germany. Again he tried the "persevere and continue working" slogan and asked scientists who were considering emigration to remain in Germany. He hoped the crisis would abate soon and the political situation would improve.

Otto Hahn asked Planck to gather well-known German professors in order to issue a public proclamation against the treatment of Jewish professors, but Planck replied, "If you are able to gather today 30 such gentlemen, then tomorrow 150 others will come and speak against it, because they are eager to take over the positions of the others."^[20] Under Planck's leadership, the Kaiser Wilhelm Society (KWG) avoided open conflict with the Nazi regime, except concerning Fritz Haber. Planck tried to discuss the issue with Adolf Hitler but was unsuccessful. In the following year, 1934, Haber died in exile.

One year later, Planck, having been the president of the KWG since 1930, organized in a somewhat provocative style an official commemorative meeting for Haber. He also succeeded in secretly enabling a number of Jewish scientists to continue working in institutes of the KWG for several years. In 1936, his term as president of the KWG ended, and the Nazi government pressured him to refrain from seeking another term.

As the political climate in Germany gradually became more hostile, Johannes Stark, prominent exponent of Deutsche Physik ("German Physics", also called "Aryan Physics") attacked Planck, Sommerfeld and Heisenberg for continuing to teach the theories of Einstein, calling them "white Jews". The "Hauptamt Wissenschaft" (Nazi government office for science) started an investigation of Planck's ancestry, claiming that he was "1/16 Jewish"; however, Planck himself denied this.^[21]

In 1938, Planck celebrated his 80th birthday. The DPG held a celebration, during which the Max-Planck medal (founded as the highest medal by the DPG in 1928) was awarded to French physicist Louis de Broglie. At the end of 1938, the Prussian Academy lost its remaining independence and was taken over by Nazis (Gleichschaltung). Planck protested by resigning his presidency. He continued to travel frequently, giving numerous public talks, such as his talk on Religion and Science, and five years later he was sufficiently fit to climb 3,000-meter peaks in the Alps.

During the Second World War the increasing number of Allied bombing missions against Berlin forced Planck and his wife to temporarily leave the city and live in the countryside. In 1942 he wrote: "In me an ardent desire has grown to persevere this crisis and live long enough to be able to witness the turning point, the beginning of a new rise." In February 1944 his home in Berlin was completely destroyed by an air raid, annihilating all his scientific records and correspondence. His rural retreat was threatened by the rapid advance of the Allied armies from both sides. After the end of the war Planck, his second wife, and his son by her were brought to a relative in Göttingen, where Planck died on October 4, 1947.

Planck endured many personal tragedies after the age of fifty. In 1909, his first wife died after 22 years of marriage, leaving him with two sons and twin daughters. Planck's older son, Karl, was killed in action in 1916 during the First World War. His daughter Margarete died in childbirth in 1917 and another daughter, Emma, married her late sister's husband and then also died in childbirth in 1919. In 1945, Planck's younger son, Erwin, was arrested due to the attempted assassination of Hitler in the July 20 plot. Erwin consequently died at the hands of the Gestapo; his death destroyed much of Max Planck's will to live.^[22]

Religious views

Planck was a member of the Lutheran Church in Germany.^[23] However, Planck was very tolerant towards alternative views and religions.^[24] In a lecture in 1937 entitled "Religion und Naturwissenschaft" he suggested the importance of these symbols and rituals related directly with a believer's ability to worship God, but that one must be mindful that the symbols provide an imperfect illustration of divinity. He criticized atheism for being focused on the derision of such symbols, while at the same time warned of the over-estimation of the importance of such symbols by believers.^[25]

Max Planck said in 1944, "As a man who has devoted his whole life to the most clear headed science, to the study of matter, I can tell you as a result of my research about atoms this much: There is no matter as such. All matter originates and exists only by virtue of a force which brings the particle of an atom to vibration and holds this most minute solar system of the atom together. We must assume behind this force the existence of a conscious and intelligent mind. This mind is the matrix of all matter."^[26]

Planck regarded the scientist as a man of imagination and faith, "faith" interpreted as being similar to "having a working hypothesis". For example the causality principle isn't true or false, it is an act of faith. Thereby Planck may have indicated a view that points toward Imre Lakatos' research programs process descriptions, where falsification is mostly tolerable, in faith of its future removal.^[24] He also said: "Both Religion and science require a belief in God. For believers, God is in the beginning, and for physicists He is at the end of all considerations… To the former He is the foundation, to the latter, the crown of the edifice of every generalized world view".^[27]

On the other hand, Planck wrote, "...'to believe' means 'to recognize as a truth,' and the knowledge of nature, continually advancing on incontestably safe tracks, has made it utterly impossible for a person possessing some training in natural science to recognize as founded on truth the many reports of extraordinary occurrences contradicting the laws of nature, of miracles which are still commonly regarded as essential supports and confirmations of religious doctrines, and which formerly used to be accepted as facts pure and simple, without doubt or criticism. The belief in miracles must retreat step by step before relentlessly and reliably progressing science and we cannot doubt that sooner or later it must vanish completely."^[28]

Later in life, Planck's views on God were that of a deist.^[29] For example, six months before his death a rumour started that Planck had converted to Catholicism, but when questioned what had brought him to make this step, he declared that, although he had always been deeply religious, he did not believe "in a personal God, let alone a Christian God."^[30]

Publications

• Planck, M. (1900a). "Über eine Verbesserung der Wienschen Spektralgleichung". Verhandlungen der Deutschen Physikalischen Gesellschaft 2: 202–204.  Translated in ter Haar, D. (1967). "On an Improvement of Wien's Equation for the Spectrum". The Old Quantum Theory. Pergamon Press. pp. 79–81. LCCN 66029628. 
• Planck, M. (1900b). "Zur Theorie des Gesetzes der Energieverteilung im Normalspektrum". Verhandlungen der Deutschen Physikalischen Gesellschaft 2: 237.  Translated in ter Haar, D. (1967). "The Old Quantum Theory". Pergamon Press. p. 82. LCCN 66029628.  |chapter= ignored (help)
• Planck, M. (1900c). "Entropie und Temperatur strahlender Wärme" [Entropy and Temperature of Radiant Heat]. Annalen der Physik 306 (4): 719–737. Bibcode:1900AnP...306..719P. doi:10.1002/andp.19003060410. 
• Planck, M. (1900d). "Über irreversible Strahlungsvorgänge" [On Irreversible Radiation Processes]. Annalen der Physik 306 (1): 69–122. Bibcode:1900AnP...306...69P. doi:10.1002/andp.19003060105. 
• Planck, M. (1901). "Über das Gesetz der Energieverteilung im Normalspektrum". Annalen der Physik 309 (3): 553–563. Bibcode:1901AnP...309..553P. doi:10.1002/andp.19013090310.  Translated in Ando, K. "On the Law of Distribution of Energy in the Normal Spectrum". Retrieved 2011-10-13. 
• Planck, M. (1903). Treatise on Thermodynamics. Ogg, A. (transl.). London: Longmans, Green & Co. OL 7246691M. 
• Planck, M. (1906). Vorlesungen über die Theorie der Wärmestrahlung. Leipzig: J.A. Barth. LCCN 07004527. 
• Planck, M. (1914). The Theory of Heat Radiation. Masius, M. (transl.) (2nd ed.). P. Blakiston's Son & Co. OL 7154661M. 
• Planck, M. (1915). Eight Lectures on Theoretical Physics. Wills, A. P. (transl.). Dover Publications. ISBN 0-486-69730-4. 
• Planck, M. (1943). "Zur Geschichte der Auffindung des physikalischen Wirkungsquantums". Naturwissenschaften 31 (14–15): 153–159. Bibcode:1943NW.....31..153P. doi:10.1007/BF01475738. 

Modern physics

From Wikipedia, the free encyclopedia

Classical physics is usually concerned with everyday conditions: speeds much lower than the speed of light, and sizes much greater than that of atoms. Modern physics is usually concerned with high velocities and small distances.

The term modern physics refers to the post-Newtonian conception of physics. In simpler form, modern physics deals with the underlying structure of the smallest particles in nature (quantum mechanics), as well as a rigorous understanding of the fundamental interaction of particles, understood as forces. Small velocities and large distances is usually the realm of classical physics. Modern physics often involves extreme conditions; quantum effects usually involve distances comparable to atoms (roughly 10⁻⁹ m), while relativistic effects usually involve velocities comparable to the speed of light (roughly 10⁸ m/s).

The term "modern physics" implies that classical descriptions of phenomena are lacking, and that an accurate, "modern", description of reality requires theories to incorporate elements of quantum mechanics or Einsteinian relativity, or both. In general, the term is used to refer to any branch of physics either developed in the early 20th century and onwards, or branches greatly influenced by early 20th century physics.

Overview

In a literal sense, the term modern physics, means up-to-date physics. In this sense, a significant portion of so-called classical physics is modern. However, since roughly 1890, new discoveries have caused significant paradigm shifts: the advent of quantum mechanics (QM), and of Einsteinian relativity (ER). Physics that incorporates elements of either QM or ER (or both) is said to be modern physics. It is in this latter sense that the term is generally used.

Modern physics is often encountered when dealing with extreme conditions. Quantum mechanical effects tend to appear when dealing with "lows" (low temperatures, small distances), while relativistic effects tend to appear when dealing with "highs" (high velocities, large distances), the "middles" being classical behaviour. For example, when analysing the behaviour of a gas at room temperature, most phenomena will involve the (classical) Maxwell–Boltzmann distribution. However near absolute zero, the Maxwell–Boltzmann distribution fails to account for the observed behaviour of the gas, and the (modern) Fermi–Dirac or Bose–Einstein distributions have to be used instead.

• 

  German physicist Albert Einstein, founder of the theory of relativity.
• 

  German physicist Max Planck, founder of quantum theory.

Very often, it is possible to find – or "retrieve" – the classical behaviour from the modern description by analysing the modern description at low speeds and large distances (by taking a limit, or by making an approximation). When doing so, the result is called the classical limit.

Classical physics (Rayleigh–Jeans law, black line) failed to explain black body radiation – the so-called ultraviolet catastrophe. The quantum description (Planck's law, colored lines) is said to be modern physics.

“	The term "modern physics," taken literally, means of course, the sum total of knowledge under the head of present-day physics. In this sense, the physics of 1890 is still modern; very few statements made in a good physics text of 1890 would need to be deleted today as untrue... On the other hand... there have been enormous advances in physics, and some of these advances have brought into question, or have directly contradicted, certain theories that had seemed to be strongly supported by the experimental evidence. For example, few, if any physicists in 1890 questioned the wave theory of light. Its triumphs over the old corpuscular theory seemed to be final and complete, particularly after the brilliant experiments of Hertz, in 1887, which demonstrated, beyond doubt, the fundamental soundness of Maxwell's electromagnetic theory of light. And yet... these very experiments of Hertz brought to light a new phenomenon—the photoelectric effect—which played an important part in establishing the quantum theory. The latter theory... is diametrically opposed to the wave theory of light; indeed, the reconciliation of these two theories... was one of the great problems of the first quarter of the twentieth century.	”
—F.K. Richtmyer, E.H. Kennard, T. Lauritsen, Introduction to Modern Physics, 5th edition (1955)[1]

Hallmarks of modern physics

These are generally considered to be the topics regarded as the "core" of the foundation of modern physics:

• Atomic theory and the evolution of the atomic model in general
• Black-body radiation
• Franck–Hertz experiment
• Geiger–Marsden experiment (Rutherford's experiment)
• Gravitational lensing
• Michelson–Morley experiment
• Photoelectric effect
• Quantum thermodynamics
• Radioactive phenomena in general
• Perihelion precession of Mercury
• Stern–Gerlach experiment
• Wave–particle duality