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Max Planck

Planck in 1933

BornMax Karl Ernst Ludwig PlanckApril 23, 1858Kiel,Duchy of Holstein

DiedOctober 4, 1947(aged89)Gttingen,Lower Saxony,Germany

NationalityGerman

FieldsPhysics

InstitutionsUniversity of KielUniversity of BerlinUniversity of GttingenKaiser-Wilhelm-Gesellschaft

Alma materLudwig Maximilian University of Munich

Doctoral advisorAlexander von Brill

Doctoral studentsGustav Ludwig HertzErich KretschmannWalther MeissnerWalter SchottkyMax von LaueMax AbrahamMoritz SchlickWalther BotheJulius Edgar Lilienfeld

Othernotable studentsLise Meitner

KnownforPlanck constantPlanck postulatePlanck's law of black body radiation

Notable awardsNobel Prize in Physics(1918)Goethe Prize(1945)

SpouseMarie Merck(18871909)Marga von Hsslin(19111947)

Signature

NotesHis sonErwin Planckwas executed in 1945 by theGestapofor his part in the assassination attempt of Adolph HitlerJuly 20 plot.

Max Karl Ernst Ludwig Planck,FRS[1](April 23, 1858 October 4, 1947) was aGermantheoretical physicistwho originatedquantum theory, which won him theNobel Prize in Physicsin 1918.[2]Planck made many contributions totheoretical physics, but his fame rests primarily on his role as originator of the quantum theory. This theory revolutionized human understanding of atomic and subatomic processes, just asAlbert Einsteinstheory of relativityrevolutionized the understanding of space and time. Together they constitute the fundamental theories of 20th-century physics.Contents[hide] 1Early life and career 1.1Academic career 1.2Family 1.3Professor at Berlin University 1.4Black-body radiation 1.5Einstein and the theory of relativity 1.6World War I 1.7Post War and Weimar Republic 1.8Quantum mechanics 1.9Nazi dictatorship and the Second World War 2Religious views 3Honors and awards 4Publications 5See also 6References 7Bibliography 8External linksEarly life and career[edit]Planck came from a traditional, intellectual family. His paternal great-grandfather and grandfather were boththeologyprofessorsinGttingen; his father was alawprofessor inKielandMunich.

Max Planck's signature at ten years of age.Planck was born inKiel,Holstein, to Johann Julius Wilhelm Planck and his second wife, Emma Patzig. He was baptised with the name ofKarl Ernst Ludwig Marx Planck; of his given names,Marx(a now obsolete variant ofMarkusor maybe simply an error forMax, which is actually short forMaximilian) was indicated as theprimary name.[3]However, by the age of ten he signed with the nameMaxand used this for the rest of his life.[4]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 ofPrussianandAustriantroops into Kiel during theSecond Schleswig Warin 1864. In 1867 the family moved toMunich, and Planck enrolled in the Maximiliansgymnasiumschool, where he came under the tutelage of Hermann Mller, amathematicianwho took an interest in the youth, and taught himastronomyandmechanicsas well as mathematics. It was from Mller that Planck first learned the principle of conservation of energy. Planck graduated early, at age 17.[5]This is how Planck first came in contact with the field of physics.Planck was gifted when it came tomusic. He took singing lessons and playedpiano,organandcello, and composedsongsandoperas. However, instead of music he chose to studyphysics.

Planck as a young man, 1878The Munich physics professorPhilipp von Jollyadvised Planck against going into physics, saying, "in this field, almost everything is already discovered, and all that remains is to fill a few holes."[6]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 theUniversity of Munich. Under Jolly's supervision, Planck performed the only experiments of his scientific career, studying thediffusionofhydrogenthrough heatedplatinum, but transferred totheoretical physics.[when?]In 1877 he went toBerlinfor a year of study with physicistsHermann von HelmholtzandGustav Kirchhoffand mathematicianKarl 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 ofClausius'swritings, 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,ber den zweiten Hauptsatz der mechanischen Wrmetheorie(On the second law of thermodynamics). He briefly taught mathematics and physics at his former school in Munich.In June 1880, he presented hishabilitationthesis,Gleichgewichtszustnde isotroper Krper in verschiedenen Temperaturen(Equilibrium states of isotropic bodies at different temperatures).Academic career[edit]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 ofheat theoryand discovered one after another the samethermodynamicalformalism asGibbswithout realizing it. Clausius's ideas onentropyoccupied a central role in his work.In April 1885 theUniversity of Kielappointed Planck as associate professor oftheoretical physics. Further work on entropy and its treatment, espQuantum mechanicsFrom Wikipedia, the free encyclopedia

For a generally accessible and less technical introduction to the topic, seeIntroduction to quantum mechanics.

Quantum mechanics

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Quantum mechanics(QM also known asquantum physics, orquantum theory) is a branch ofphysicswhich deals with physical phenomena atnanoscopic scaleswhere theactionis on the order of thePlanck constant. It departs fromclassical mechanicsprimarily at thequantum realmofatomicandsubatomiclength scales. Quantum mechanics provides a mathematical description of much of the dualparticle-likeandwave-likebehavior and interactions ofenergyandmatter. Quantum mechanics provides a substantially useful framework for many features of the modernperiodic table of elementsincluding the behavior of atoms duringchemical bondingand has played a significant role in the development of many modern technologies.In advanced topics of quantum mechanics, some of these behaviors aremacroscopic(seemacroscopic quantum phenomena) and emerge at only extreme (i.e., very low or very high) energies ortemperatures(such as in the use ofsuperconducting magnets). For example, theangular momentumof an electron bound to anatomormoleculeis quantized. In contrast, the angular momentum of an unbound electron is not quantized. In the context of quantum mechanics, thewaveparticle dualityof energy and matter and theuncertainty principleprovide a unified view of the behavior ofphotons,electrons, and other atomic-scale objects.Themathematical formulations of quantum mechanicsare abstract. A mathematical function, thewavefunction, provides information about theprobability amplitudeof position, momentum, and other physical properties of a particle. Mathematical manipulations of the wavefunction usually involvebraket notationwhich requires an understanding ofcomplex numbersandlinear functionals. The wavefunction formulation treats the particle as aquantum harmonic oscillator, and the mathematics is akin to that describingacoustic resonance. Many of the results of quantum mechanics are not easily visualized in terms ofclassical mechanics. For instance, in a quantum mechanical model the lowest energy state of a system, theground state, is non-zero as opposed to a more "traditional" ground state with zerokinetic energy(all particles at rest). Instead of a traditional static, unchanging zero energy state, quantum mechanics allows for far more dynamic, chaotic possibilities, according toJohn Wheeler.The earliest versions of quantum mechanics were formulated in the first decade of the 20th century. About this time, theatomic theoryand thecorpuscular theory of light(as updated byEinstein)[1]first came to be widely accepted as scientific fact; these latter theories can be viewed as quantum theories ofmatterandelectromagnetic radiation, respectively.Early quantum theorywas significantly reformulated in the mid-1920s byWerner Heisenberg,Max BornandPascual Jordan, (matrix mechanics);Louis de BroglieandErwin Schrdinger(wave mechanics); andWolfgang PauliandSatyendra Nath Bose(statistics of subatomic particles). Moreover, theCopenhagen interpretationofNiels Bohrbecame widely accepted. By 1930, quantum mechanics had been further unified and formalized by the work ofDavid Hilbert,Paul DiracandJohn von Neumann[2]with a greater emphasis placed onmeasurement in quantum mechanics, the statistical nature of our knowledge of reality, andphilosophical speculation about the role of the observer. Quantum mechanics has since permeated throughout many aspects of 20th-century physics and other disciplines includingquantum chemistry,quantum electronics,quantum optics, andquantum information science. Much 19th-century physics has been re-evaluated as the "classical limit" of quantum mechanics and its more advanced developments in terms ofquantum field theory,string theory, and speculativequantum gravitytheories.The namequantum mechanicsderives from the observation that some physical quantities can change only indiscreteamounts (Latinquanta), and not in a continuous (cf.analog) way.Contents[hide] 1History 2Mathematical formulations 3Mathematically equivalent formulations of quantum mechanics 4Interactions with other scientific theories 4.1Quantum mechanics and classical physics 4.2Relativity and quantum mechanics 4.3Attempts at a unified field theory 5Philosophical implications 6Applications 7Examples 7.1Free particle 7.2Step potential 7.3Rectangular potential barrier 7.4Particle in a box 7.5Finite potential well 7.6Harmonic oscillator 8See also 9Notes 10References 11Further reading 12External linksHistory[edit]Modern physics

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Main article:History of quantum mechanicsScientific inquiry into the wave nature of light began in the 17th and 18th centuries when scientists such asRobert Hooke,Christiaan HuygensandLeonhard Eulerproposed a wave theory of light based on experimental observations.[3]In 1803,Thomas Young, an Englishpolymath, performed the famousdouble-slit experimentthat he later described in a paper entitled "On the nature of light and colours". This experiment played a major role in the general acceptance of thewave theory of light.In 1838, with the discovery ofcathode raysbyMichael Faraday, these studies were followed by the 1859 statement of theblack-body radiationproblem byGustav Kirchhoff, the 1877 suggestion byLudwig Boltzmannthat the energy states of a physical system can be discrete, and the 1900 quantum hypothesis ofMax Planck.[4]Planck's hypothesis that energy is radiated and absorbed in discrete "quanta" (or "energy elements") precisely matched the observed patterns of black-body radiation.In 1896,Wilhelm Wienempirically determined a distribution law of black-body radiation,[5]known asWien's lawin his honor. Ludwig Boltzmann independently arrived at this result by considerations ofMaxwell's equations. However, it was valid only at high frequencies, and underestimated the radiance at low frequencies. Later,Max Planckcorrected this model using Boltzmann statistical interpretation of thermodynamics and proposed what is now calledPlanck's law, which led to the development of quantum mechanics.Among the first to study quantum phenomena in nature wereArthur Compton,C.V. Raman,Pieter Zeeman, each of whom has a quantum effect named after him.Robert A. Millikanstudied thePhotoelectric effectexperimentally andAlbert Einsteindeveloped a theory for it. At the same timeNiels Bohrdeveloped his theory of the atomic structure which was later confirmed by the experiments ofHenry Moseley. In 1913,Peter Debyeextended Niels Bohr's theory of atomic structure, introducingelliptical orbits, a concept also introduced byArnold Sommerfeld.[6]This phase is known asOld quantum theory.According to Planck, each energy element,E, is proportional to itsfrequency,:

Max Planckis considered the father of the Quantum TheorywherehisPlanck's constant. Planck (cautiously) insisted that this was simply an aspect of theprocessesof absorption and emission of radiation and had nothing to do with thephysical realityof the radiation itself.[7]In fact, he considered hisquantum hypothesisa mathematical trick to get the right answer rather than a sizeable discovery.[citation needed]However, in 1905Albert Einsteininterpreted Planck's quantum hypothesisrealisticallyand used it to explain thephotoelectric effectin which shining light on certain materials can eject electrons from the material.

The 1927Solvay ConferenceinBrussels.The foundations of quantum mechanics were established during the first half of the 20th century byMax Planck,Niels Bohr,Werner Heisenberg,Louis de Broglie,Arthur Compton,Albert Einstein,Erwin Schrdinger,Max Born,John von Neumann,Paul Dirac,Enrico Fermi,Wolfgang Pauli,Max von Laue,Freeman Dyson,David Hilbert,Wilhelm Wien,Satyendra Nath Bose,Arnold Sommerfeldandothers. In the mid-192