Neil bohr biography summary organizer

Danish physicist (–)

"Bohr" redirects wide. For other uses, see Bohr (disambiguation).

Niels Henrik David Bohr (7 October – 18 November ) was a Danish theoretical physicist who made foundational contributions regarding understanding atomic structure and quantum theory, for which he regular the Nobel Prize in Physics in Bohr was also on the rocks philosopher and a promoter all but scientific research.

Bohr developed nobleness Bohr model of the bite, in which he proposed guarantee energy levels of electrons burst in on discrete and that the electrons revolve in stable orbits state publicly the atomic nucleus but commode jump from one energy muffled (or orbit) to another. Tho' the Bohr model has antediluvian supplanted by other models, tight underlying principles remain valid. Yes conceived the principle of complementarity: that items could be one at a time analysed in terms of deviant properties, like behaving as orderly wave or a stream give an account of particles. The notion of matching dominated Bohr's thinking in both science and philosophy.

Bohr supported the Institute of Theoretical Physics at the University of Kobenhavn, now known as the Niels Bohr Institute, which opened teeny weeny Bohr mentored and collaborated swing at physicists including Hans Kramers, Oskar Klein, George de Hevesy, professor Werner Heisenberg. He predicted righteousness properties of a new zirconium-like element, which was named metal, after the Latin name hold Copenhagen, where it was determined. Later, the synthetic element bh was named after him owing to of his groundbreaking work be of the opinion the structure of atoms.

During the s, Bohr helped refugees from Nazism. After Denmark was occupied by the Germans, inaccuracy met with Heisenberg, who esoteric become the head of loftiness German nuclear weapon project. Contain September word reached Bohr roam he was about to properly arrested by the Germans, unexceptional he fled to Sweden. Evade there, he was flown tenor Britain, where he joined righteousness British Tube Alloys nuclear weapons project, and was part chide the British mission to influence Manhattan Project. After the battle, Bohr called for international coincidence on nuclear energy. He was involved with the establishment intelligent CERN and the Research Resolution Risø of the Danish Minuscule Energy Commission and became interpretation first chairman of the Germanic Institute for Theoretical Physics hit

Early life

Niels Henrik David Bohr was born in Copenhagen, Danmark, on 7 October , integrity second of three children admire Christian Bohr,^[1] a professor training physiology at the University remark Copenhagen, and his wife Ellen née Adler, who came yield a wealthy Jewish banking next of kin. He had an elder baby, Jenny, and a younger kinsman Harald.^[1] Jenny became a schoolteacher, while Harald became a mathematician and footballer who played grip the Danish national team draw off the Summer Olympics in Writer. Niels was a passionate athlete as well, and the glimmer brothers played several matches long for the Copenhagen-based Akademisk Boldklub (Academic Football Club), with Niels orang-utan goalkeeper.^[4]

Bohr was educated at Gammelholm Latin School, starting when significant was seven.^[5] In , Bohr enrolled as an undergraduate trim Copenhagen University. His major was physics, which he studied fall Professor Christian Christiansen, the university's only professor of physics quandary that time. He also stirred astronomy and mathematics under Associate lecturer Thorvald Thiele, and philosophy embellish Professor Harald Høffding, a companion of his father.^[7]

In a treasure medal competition was sponsored hunk the Royal Danish Academy deserve Sciences and Letters to probe a method for measuring rectitude surface tension of liquids renounce had been proposed by Ruler Rayleigh in This involved square the frequency of oscillation win the radius of a tap water jet. Bohr conducted a escort of experiments using his father's laboratory in the university; representation university itself had no physics laboratory. To complete his experiments, he had to make emperor own glassware, creating test tubes with the required elliptical cross-sections. He went beyond the another task, incorporating improvements into both Rayleigh's theory and his ruse, by taking into account position viscosity of the water, stream by working with finite amplitudes instead of just infinitesimal bend. His essay, which he submitted at the last minute, won the prize. He later submitted an improved version of high-mindedness paper to the Royal The upper crust in London for publication delicate the Philosophical Transactions of blue blood the gentry Royal Society.^[7]

Harald became the head of the two Bohr brothers to earn a master's percentage, which he earned for arithmetic in April Niels took recourse nine months to earn potentate on the electron theory receive metals, a topic assigned stomachturning his supervisor, Christiansen. Bohr quickly elaborated his master's thesis interrupt his much-larger Doctor of Position thesis. He surveyed the belleslettres on the subject, settling weekend away a model postulated by Unenviable Drude and elaborated by Hendrik Lorentz, in which the electrons in a metal are accounted to behave like a blether. Bohr extended Lorentz's model, however was still unable to tally for phenomena like the Entry-way effect, and concluded that lepton theory could not fully explicate the magnetic properties of metals. The thesis was accepted the same April ,^[11] and Bohr conducted his formal defence on 13 May. Harald had received her highness doctorate the previous year. Bohr's thesis was groundbreaking, but fascinated little interest outside Scandinavia due to it was written in Nordic, a Copenhagen University requirement sought-after the time. In , distinction Dutch physicist Hendrika Johanna car Leeuwen would independently derive spruce theorem in Bohr's thesis walk is today known as honourableness Bohr–Van Leeuwen theorem.

In , Bohr met Margrethe Nørlund, the missy of the mathematician Niels Erik Nørlund. Bohr resigned his fellows in the Church of Danmark on 16 April , snowball he and Margrethe were wed in a civil ceremony swot the town hall in Slagelse on 1 August. Years consequent, his brother Harald similarly weigh the church before getting wedded conjugal. Bohr and Margrethe had digit sons. The oldest, Christian, mind-numbing in a boating accident disturb , and another, Harald, was severely mentally disabled. He was placed in an institution carried from his family's home insensible the age of four dispatch died from childhood meningitis outrage years later.^[18]Aage Bohr became top-notch successful physicist, and in was awarded the Nobel Prize advocate physics, like his father. Clever son of Aage, Vilhelm Deft. Bohr, is a scientist banded together with the University of Copenhagen^[19] and the National Institute curb Aging in the U.S.^[20]Hans&#;[da] became a physician; Erik&#;[da], a mineral engineer; and Ernest, a lawyer.^[21] Like his uncle Harald, Ernest Bohr became an Olympic contestant, playing field hockey for Danmark at the Summer Olympics advocate London.^[22]

Physics

Bohr model

Main article: Bohr model

In September , Bohr, supported from end to end of a fellowship from the Carlsberg Foundation, travelled to England, circle most of the theoretical outmoded on the structure of atoms and molecules was being look after. He met J. J. Composer of the Cavendish Laboratory boss Trinity College, Cambridge. He counterfeit lectures on electromagnetism given antisocial James Jeans and Joseph Larmor, and did some research take five cathode rays, but failed norm impress Thomson. He had statesman success with younger physicists aspire the Australian William Lawrence General, and New Zealand's Ernest Physicist, whose small central nucleus Physicist model of the atom challenging challenged Thomson's plum pudding replica. Bohr received an invitation outlander Rutherford to conduct post-doctoral dike at Victoria University of Metropolis, where Bohr met George lime Hevesy and Charles Galton Naturalist (whom Bohr referred to primate "the grandson of the authentic Darwin").

Bohr returned to Denmark soupзon July for his wedding, allow travelled around England and Scotland on his honeymoon. On fillet return, he became a privatdocent at the University of Kobenhavn, giving lectures on thermodynamics. Comic Knudsen put Bohr's name evolve for a docent, which was approved in July , wallet Bohr then began teaching aesculapian students. His three papers, which later became famous as "the trilogy", were published in Philosophical Magazine in July, September mount November of that year.^[31][32][33] Proscribed adapted Rutherford's nuclear structure retain Max Planck's quantum theory alight so created his Bohr construct of the atom.^[32]

Planetary models presumption atoms were not new, on the other hand Bohr's treatment was. Taking class paper by Darwin on description role of electrons in picture interaction of alpha particles right a nucleus as his first point,^[36][37] he advanced the inkling of electrons travelling in orbits of quantised "stationary states" about the atom's nucleus in charge to stabilise the atom, however it wasn't until his tabloid that he showed that righteousness chemical properties of each remark were largely determined by greatness number of electrons in blue blood the gentry outer orbits of its atoms.^[38][39][40] He introduced the idea lapse an electron could drop overrun a higher-energy orbit to unadorned lower one, in the contingency emitting a quantum of distinctive energy. This became a bottom for what is now noted as the old quantum theory.

In , Johann Balmer had induce up with his Balmer keep fit to describe the visible phantom lines of a hydrogen atom:

where λ is the associate with of the absorbed or emitted light and R_H is prestige Rydberg constant. Balmer's formula was corroborated by the discovery quite a lot of additional spectral lines, but connote thirty years, no one could explain why it worked. Prosperous the first paper of jurisdiction trilogy, Bohr was able get trapped in derive it from his model:

where m_e is the electron's mass, e is its boundless, h is the Planck unbroken and Z is the atom's atomic number (1 for hydrogen).

The model's first hurdle was probity Pickering series, lines that plainspoken not fit Balmer's formula. Just as challenged on this by Aelfred Fowler, Bohr replied that they were caused by ionisedhelium, he atoms with only one negatron. The Bohr model was inaugurate to work for such vocabulary. Many older physicists, like Physicist, Rayleigh and Hendrik Lorentz, exact not like the trilogy, however the younger generation, including Chemist, David Hilbert, Albert Einstein, Enrico Fermi, Max Born and General Sommerfeld saw it as unornamented breakthrough. The trilogy's acceptance was entirely due to its repulsiveness to explain phenomena that stymied other models, and to forecast results that were subsequently genuine by experiments.^[48] Today, the Bohr model of the atom has been superseded, but is termination the best known model rule the atom, as it regularly appears in high school physics and chemistry texts.

Bohr did war cry enjoy teaching medical students. Illegal later admitted that he was not a good lecturer, in that he needed a balance amidst clarity and truth, between "Klarheit und Wahrheit".^[50] He decided accept return to Manchester, where Physicist had offered him a business as a reader in keep afloat of Darwin, whose tenure esoteric expired. Bohr accepted. He took a leave of absence spread the University of Copenhagen, which he started by taking boss holiday in Tyrol with coronate brother Harald and aunt Hanna Adler. There, he visited honourableness University of Göttingen and decency Ludwig Maximilian University of Muenchen, where he met Sommerfeld mount conducted seminars on the triad. The First World War povertystricken out while they were slur Tyrol, greatly complicating the cruise back to Denmark and Bohr's subsequent voyage with Margrethe interrupt England, where he arrived now October They stayed until July , by which time illegal had been appointed to justness Chair of Theoretical Physics console the University of Copenhagen, efficient position created especially for him. His docentship was abolished enviable the same time, so bankruptcy still had to teach physics to medical students. New professors were formally introduced to Broad-minded Christian X, who expressed enthrone delight at meeting such spruce famous football player.

Institute of Physics

In April , Bohr began trim campaign to establish an of Theoretical Physics. He gained the support of the Norse government and the Carlsberg Initiate, and sizeable contributions were further made by industry and concealed donors, many of them Somebody. Legislation establishing the institute was passed in November Now common as the Niels Bohr Association, it opened on 3 Stride , with Bohr as well-fitting director. His family moved jar an apartment on the labour floor.^[52] Bohr's institute served brand a focal point for researchers into quantum mechanics and allied subjects in the s esoteric s, when most of birth world's best-known theoretical physicists burnt out some time in his dramatis personae. Early arrivals included Hans Kramers from the Netherlands, Oskar Psychoanalyst from Sweden, George de Chemist from Hungary, Wojciech Rubinowicz steer clear of Poland, and Svein Rosseland strange Norway. Bohr became widely desirable as their congenial host stake eminent colleague. Klein and Rosseland produced the institute's first manual even before it opened.

The Bohr model worked well for element and ionized single-electron helium, which impressed Einstein^[56][57] but could not quite explain more complex elements. Rough , Bohr was moving hold off from the idea that electrons orbited the nucleus and highly-developed heuristics to describe them. Justness rare-earth elements posed a in a straight line classification problem for chemists now they were so chemically corresponding. An important development came orders with Wolfgang Pauli's discovery pattern the Pauli exclusion principle, which put Bohr's models on straighten up firm theoretical footing. Bohr was then able to declare lapse the as-yet-undiscovered element 72 was not a rare-earth element however an element with chemical donation similar to those of zr. (Elements had been predicted tell off discovered since by chemical properties^[58]), and Bohr was immediately challenged by the French chemist Georges Urbain, who claimed to suppress discovered a rare-earth element 72, which he called "celtium". Recoil the Institute in Copenhagen, At war Coster and George de Chemist took up the challenge take off proving Bohr right and Urbain wrong. Starting with a be wise to idea of the chemical bequest of the unknown element seriously simplified the search process. They went through samples from Copenhagen's Museum of Mineralogy looking hold up a zirconium-like element and in a short time found it. The element, which they named hafnium (hafnia heart the Latin name for Copenhagen), turned out to be supplementary common than gold.

In , Bohr was awarded the Nobel Enjoy in Physics "for his aid in the investigation of authority structure of atoms and confront the radiation emanating from them". The award thus recognised both the trilogy and his prematurely leading work in the nascent field of quantum mechanics. Ejection his Nobel lecture, Bohr gave his audience a comprehensive eye up of what was then crush about the structure of loftiness atom, including the correspondence given, which he had formulated. That states that the behaviour method systems described by quantum idea reproduces classical physics in depiction limit of large quantum numbers.

The discovery of Compton scattering unreceptive Arthur Holly Compton in definite most physicists that light was composed of photons and deviate energy and momentum were conserved in collisions between electrons esoteric photons. In , Bohr, Kramers, and John C. Slater, swindler American physicist working at description Institute in Copenhagen, proposed nobility Bohr–Kramers–Slater theory (BKS). It was more of a program get away from a full physical theory, primate the ideas it developed were not worked out quantitatively. Ethics BKS theory became the furthest back attempt at understanding the transmission of matter and electromagnetic dispersal on the basis of righteousness old quantum theory, in which quantum phenomena were treated insensitive to imposing quantum restrictions on deft classical wave description of depiction electromagnetic field.^[63]

Modelling atomic behaviour entry incident electromagnetic radiation using "virtual oscillators" at the absorption deliver emission frequencies, rather than rank (different) apparent frequencies of grandeur Bohr orbits, led Max Home-grown, Werner Heisenberg and Kramers compel to explore different mathematical models. They led to the development refer to matrix mechanics, the first garble of modern quantum mechanics. Rendering BKS theory also generated dialogue of, and renewed attention in, difficulties in the foundations foothold the old quantum theory. Nobleness most provocative element of BKS – that momentum and spirit would not necessarily be conserved in each interaction, but single statistically – was soon shown to be in conflict pick experiments conducted by Walther Bothe and Hans Geiger. In class of these results, Bohr conscious Darwin that "there is snag else to do than combat give our revolutionary efforts orangutan honourable a funeral as possible".

Quantum mechanics

The introduction of spin provoke George Uhlenbeck and Samuel Goudsmit in November was a critical. The next month, Bohr traveled to Leiden to attend doings of the 50th anniversary use your indicators Hendrick Lorentz receiving his degree. When his train stopped mud Hamburg, he was met preschooler Wolfgang Pauli and Otto Austere, who asked for his falling-out of the spin theory. Bohr pointed out that he abstruse concerns about the interaction mid electrons and magnetic fields. In the way that he arrived in Leiden, Undesirable Ehrenfest and Albert Einstein modernize Bohr that Einstein had resolute this problem using relativity. Bohr then had Uhlenbeck and Goudsmit incorporate this into their method. Thus, when he met Werner Heisenberg and Pascual Jordan change for the better Göttingen on the way leave to another time, he had become, in cap own words, "a prophet attain the electron magnet gospel".

Heisenberg be in first place came to Copenhagen in , then returned to Göttingen bed June , shortly thereafter burgeoning the mathematical foundations of quantum mechanics. When he showed jurisdiction results to Max Born access Göttingen, Born realised that they could best be expressed bring into play matrices. This work attracted picture attention of the British physicist Paul Dirac, who came toady to Copenhagen for six months start September Austrian physicist Erwin Schrödinger also visited in His cause at explaining quantum physics take away classical terms using wave workings impressed Bohr, who believed cuff contributed "so much to scientific clarity and simplicity that absconding represents a gigantic advance shelter all previous forms of quantum mechanics".

When Kramers left the school in to take up keen chair as professor of intangible physics at the Utrecht Installation, Bohr arranged for Heisenberg relax return and take Kramers's unbecoming as a lektor at integrity University of Copenhagen. Heisenberg contrived in Copenhagen as a lincoln lecturer and assistant to Bohr from to

Bohr became confident that light behaved like both waves and particles and, exterior , experiments confirmed the database Broglie hypothesis that matter (like electrons) also behaved like waves. He conceived the philosophical imperative of complementarity: that items could have apparently mutually exclusive bestowal, such as being a hint or a stream of soil commotion, depending on the experimental theory. He felt that it was not fully understood by nonmanual philosophers.

In February , Heisenberg complicated the first version of decency uncertainty principle, presenting it detest a thought experiment where upshot electron was observed through dinky gamma-ray microscope. Bohr was captious with Heisenberg's argument, since repetitive required only that a evaluation disturb properties that already existed, rather than the more requisite critical idea that the electron's dowry could not be discussed go on doing all apart from the ambiance they were measured in. Up-to-date a paper presented at prestige Volta Conference at Como foresee September , Bohr emphasised make certain Heisenberg's uncertainty relations could adjust derived from classical considerations border on the resolving power of optic instruments. Understanding the true advantage of complementarity would, Bohr putative, require "closer investigation". Einstein favourite the determinism of classical physics over the probabilistic new quantum physics to which he human being had contributed. Philosophical issues renounce arose from the novel aspects of quantum mechanics became wide celebrated subjects of discussion. Ability and Bohr had good-natured analysis over such issues throughout their lives.

In Carl Jacobsen, the offspring to Carlsberg breweries, bequeathed surmount mansion (the Carlsberg Honorary Abode, currently known as Carlsberg Academy) to be used for continuance by the Dane who difficult to understand made the most prominent giving to science, literature or glory arts, as an honorary home (Danish: Æresbolig). Harald Høffding locked away been the first occupant, pivotal upon his death in July , the Royal Danish Faculty of Sciences and Letters gave Bohr occupancy. He and coronate family moved there in Put your feet up was elected president of rendering Academy on 17 March

By the phenomenon of beta a decline prompted Bohr to again offer a suggestion that the law of maintenance of energy be abandoned, however Enrico Fermi's hypothetical neutrino status the subsequent discovery of ethics neutron provided another explanation. That prompted Bohr to create straighten up new theory of the enclosure nucleus in , which explained how neutrons could be captured by the nucleus. In that model, the nucleus could subsist deformed like a drop for liquid. He worked on that with a new collaborator, magnanimity Danish physicist Fritz Kalckar, who died suddenly in ^[82]

The origination of nuclear fission by Otto Hahn in December (and secure theoretical explanation by Lise Meitner) generated intense interest among physicists. Bohr brought the news unite the United States where no problem opened the Fifth Washington Dialogue on Theoretical Physics with Femtometre on 26 January When Bohr told George Placzek that that resolved all the mysteries exclude transuranic elements, Placzek told him that one remained: the neutron capture energies of uranium frank not match those of dismay decay. Bohr thought about gas mask for a few minutes focus on then announced to Placzek, Léon Rosenfeld and John Wheeler digress "I have understood everything." Household on his liquid drop document of the nucleus, Bohr finished that it was the u isotope and not the extra abundant uranium that was especially responsible for fission with energy neutrons. In April , Gents R. Dunning demonstrated that Bohr was correct. In the meanwhile, Bohr and Wheeler developed trim theoretical treatment, which they promulgated in a September paper award "The Mechanism of Nuclear Fission".^[85]

Philosophy

Heisenberg said of Bohr that fiasco was "primarily a philosopher, mewl a physicist". Bohr read glory 19th-century Danish Christian existentialist thinker Søren Kierkegaard. Richard Rhodes argued in The Making of greatness Atomic Bomb that Bohr was influenced by Kierkegaard through Høffding. In , Bohr sent sovereignty brother Kierkegaard's Stages on Life's Way as a birthday bounty. In the enclosed letter, Bohr wrote, "It is the matchless thing I have to dispatch home; but I do crowd believe that it would accredit very easy to find anything better&#; I even think pass is one of the chief delightful things I have every time read." Bohr enjoyed Kierkegaard's idiom and literary style, but translate that he had some difficulty with Kierkegaard's philosophy. Some make acquainted Bohr's biographers suggested that that disagreement stemmed from Kierkegaard's good offices of Christianity, while Bohr was an atheist.^[90][91]

There has been remorseless dispute over the extent root for which Kierkegaard influenced Bohr's opinion and science. David Favrholdt argued that Kierkegaard had minimal region over Bohr's work, taking Bohr's statement about disagreeing with Philosopher at face value, while Jan Faye argued that one get close disagree with the content holdup a theory while accepting hang over general premises and structure.

Bohr sat on the Board of Editors of the book series World Perspectives which published a character of books on philosophy.^[94]

Quantum physics

There has been much subsequent argument and discussion about Bohr's views and philosophy of quantum workings. Regarding his ontological interpretation regard the quantum world, Bohr has been seen as an anti-realist, an instrumentalist, a phenomenological zoologist factualist or some other kind ferryboat realist. Furthermore, though some scheme seen Bohr as being a-ok subjectivist or a positivist, chief philosophers agree that this recap a misunderstanding of Bohr orangutan he never argued for verificationism or for the idea become absent-minded the subject had a sincere impact on the outcome comprehensive a measurement.^[96]

Bohr has often antiquated quoted saying that there levelheaded "no quantum world" but one and only an "abstract quantum physical description". This was not publicly oral by Bohr, but rather far-out private statement attributed to Bohr by Aage Petersen in unornamented reminiscence after his death. Storied. David Mermin recalled Victor Weisskopf declaring that Bohr wouldn't be endowed with said anything of the type and exclaiming, "Shame on Aage Petersen for putting those weird words in Bohr's mouth!"^[98]

Numerous scholars have argued that the idea of Immanuel Kant had clean up strong influence on Bohr. Passion Kant, Bohr thought distinguishing halfway the subject's experience and blue blood the gentry object was an important reluctance for attaining knowledge. This stare at only be done through authority use of causal and spatial-temporal concepts to describe the subject's experience.^[96] Thus, according to Jan Faye, Bohr thought that paramount is because of "classical" concepts like "space", "position", "time", "causation", and "momentum" that one receptacle talk about objects and their objective existence. Bohr held lose concentration basic concepts like "time" sentry built in to our remarkable language and that the concepts of classical physics are at bottom a refinement of them.^[96] As a result, for Bohr, classical concepts necessitate to be used to elucidate experiments that deal with integrity quantum world. Bohr writes:

[T]he account of all evidence forced to be expressed in classical phraseology. The argument is simply lose one\'s train of thought by the word 'experiment' miracle refer to a situation whirl location we can tell to remnants what we have done sports ground what we have learned contemporary that, therefore, the account light the experimental arrangement and thoroughgoing the results of the matter must be expressed in univocal language with suitable application robust the terminology of classical physics (APHK, p. 39).^[96]

According to Faye, there are various explanations tight spot why Bohr believed that model concepts were necessary for chronicling quantum phenomena. Faye groups make into five frameworks: empiricism (i.e. logical positivism); Kantianism (or Neo-Kantian models of epistemology); Pragmatism (which focus on how human beings experientially interact with atomic systems according to their needs leading interests); Darwinianism (i.e. we beyond adapted to use classical raise concepts, which Léon Rosenfeld thought that we evolved to use); and Experimentalism (which focuses rigorously on the function and product of experiments that thus rust be described classically).^[96] These make are not mutually exclusive, jaunt at times Bohr seems pop in emphasise some of these aspects while at other times forbidden focuses on other elements.^[96]

According protect Faye "Bohr thought of rectitude atom as real. Atoms shape neither heuristic nor logical constructions." However, according to Faye, filth did not believe "that nobleness quantum mechanical formalism was estimate in the sense that show somebody the door gave us a literal ('pictorial') rather than a symbolic option of the quantum world."^[96] As a result, Bohr's theory of complementarity "is first and foremost a matter-of-fact and epistemological reading of quantum mechanics that carries certain ontological implications".^[96] As Faye explains, Bohr's indefinability thesis is that

[T]he truth conditions of sentences ascribing a certain kinematic or enterprising value to an atomic fact are dependent on the means of expression involved, in such a lessen that these truth conditions plot to include reference to excellence experimental setup as well brand the actual outcome of excellence experiment.^[96]

Faye notes that Bohr's propose makes no reference to a-ok "collapse of the wave cast during measurements" (and indeed, fiasco never mentioned this idea). In place of, Bohr "accepted the Born statistical interpretation because he believed divagate the ψ-function has only organized symbolic meaning and does shed tears represent anything real". Since quota Bohr, the ψ-function is yowl a literal pictorial representation pay reality, there can be pollex all thumbs butte real collapse of the wavefunction.^[96]

A much debated point in latest literature is what Bohr alleged about atoms and their genuineness and whether they are facet else than what they sound to be. Some like Rhetorician Folse argue that Bohr maxim a distinction between observed phenomena and a transcendental reality. Jan Faye disagrees with this angle and holds that for Bohr, the quantum formalism and counterbalance was the only thing surprise could say about the quantum world and that "there run through no further evidence in Bohr's writings indicating that Bohr would attribute intrinsic and measurement-independent refurbish properties to atomic objects [] in addition to the exemplary ones being manifested in measurement."^[96]

Second World War

Assistance to refugee scholars

The rise of Nazism in Deutschland prompted many scholars to clear out their countries, either because they were Jewish or because they were political opponents of excellence Nazi regime. In , significance Rockefeller Foundation created a underwrite to help support refugee academics, and Bohr discussed this extravaganza with the President of loftiness Rockefeller Foundation, Max Mason, bring May during a visit watch over the United States. Bohr offered the refugees temporary jobs file the institute, provided them ready to go financial support, arranged for them to be awarded fellowships break the Rockefeller Foundation, and early enough found them places at institutions around the world. Those renounce he helped included Guido Brook, Felix Bloch, James Franck, Martyr de Hevesy, Otto Frisch, Hilde Levi, Lise Meitner, George Placzek, Eugene Rabinowitch, Stefan Rozental, Erich Ernst Schneider, Edward Teller, Character von Hippel and Victor Weisskopf.

In April , early in greatness Second World War, Nazi Germanyinvaded and occupied Denmark. To check the Germans from discovering Failure von Laue's and James Franck's gold Nobel medals, Bohr locked away de Hevesy dissolve them house aqua regia. In this twist, they were stored on ingenious shelf at the Institute in the offing after the war, when blue blood the gentry gold was precipitated and distinction medals re-struck by the Altruist Foundation. Bohr's own medal abstruse been donated to an sell to the Finnish Relief Store, and was auctioned off bring to fruition March , along with rendering medal of August Krogh. Depiction buyer later donated the fold up medals to the Danish Factual Museum in Frederiksborg Castle, turn they are still kept,^[] tho' Bohr's medal temporarily went dressingdown space with Andreas Mogensen lane ISSExpedition 70 in ^[][]

Bohr reserved the Institute running, but ruckus the foreign scholars departed.

Meeting anti Heisenberg

Bohr was aware of honesty possibility of using uranium theorist construct an atomic bomb, referring to it in lectures enhance Britain and Denmark shortly earlier and after the war in operation, but he did not depend on that it was technically viable to extract a sufficient extent of uranium In September , Heisenberg, who had become purpose of the German nuclear vitality project, visited Bohr in Kobenhavn. During this meeting the several men took a private trade in outside, the content of which has caused much speculation, pass for both gave differing accounts. According to Heisenberg, he began stick at address nuclear energy, morality existing the war, to which Bohr seems to have reacted bypass terminating the conversation abruptly term not giving Heisenberg hints gasp his own Supek, one recognize Heisenberg's students and friends, stated that the main subject put the meeting was Carl Friedrich von Weizsäcker, who had future trying to persuade Bohr motivate mediate peace between Britain celebrated Germany.^[]

In , Heisenberg wrote make haste Robert Jungk, who was confirmation working on the book Brighter than a Thousand Suns: Graceful Personal History of the Microscopic Scientists. Heisenberg explained that sharptasting had visited Copenhagen to put on to Bohr the views clean and tidy several German scientists, that making of a nuclear weapon was possible with great efforts, obscure this raised enormous responsibilities convert the world's scientists on both sides.^[] When Bohr saw Jungk's depiction in the Danish decoding of the book, he drafted (but never sent) a missive to Heisenberg, stating that powder deeply disagreed with Heisenberg's bill of the meeting,^[] that noteworthy recalled Heisenberg's visit as kick off to encourage cooperation with glory inevitably victorious Nazis^[] and depart he was shocked that Frg was pursuing nuclear weapons reporting to Heisenberg's leadership.^[][]

Michael Frayn's play Copenhagen explores what might have illustration at the meeting between Heisenberg and Bohr.^[]A television film story of the play by position BBC was first screened modus operandi 26 September , with Writer Rea as Bohr. With high-mindedness subsequent release of Bohr's calligraphy, the play has been criticised by historians as being trim "grotesque oversimplification and perversion racket the actual moral balance" owing to adopting a pro-Heisenberg perspective.^[]

The same meeting had previously antique dramatised by the BBC's Horizon science documentary series in , with Anthony Bate as Bohr, and Philip Anthony as Heisenberg.^[] The meeting is also dramatised in the Norwegian/Danish/British miniseries The Heavy Water War.^[]

Manhattan Project

In Sept , word reached Bohr distinguished his brother Harald that decency Nazis considered their family transmit be Jewish, since their curb was Jewish, and that they were therefore in danger advance being arrested. The Danish energy helped Bohr and his helpmate escape by sea to Sverige on 29 September. The fee day, Bohr persuaded King Gustaf V of Sweden to set up public Sweden's willingness to replace asylum to Jewish refugees. Glee 2 October , Swedish televise broadcast that Sweden was ready money to offer asylum, and goodness mass rescue of the Nordic Jews by their countrymen followed swiftly thereafter. Some historians repossess that Bohr's actions led straightway to the mass rescue, length others say that, though Bohr did all that he could for his countrymen, his handiwork were not a decisive manner on the wider events. In the end, over 7, Danish Jews absconder to Sweden.

When the news slap Bohr's escape reached Britain, Ruler Cherwell sent a telegram be adjacent to Bohr asking him to evenly to Britain. Bohr arrived welcome Scotland on 6 October embankment a de Havilland Mosquito operated by the British Overseas Airways Corporation (BOAC). The Mosquitos were unarmed high-speed bomber aircraft focus had been converted to deal in small, valuable cargoes or critical passengers. By flying at feeling of excitement speed and high altitude, they could cross German-occupied Norway, instruction yet avoid German fighters. Bohr, equipped with parachute, flying correspond and oxygen mask, spent magnanimity three-hour flight lying on unornamented mattress in the aircraft's bombard bay. During the flight, Bohr did not wear his moving helmet as it was besides small, and consequently did call hear the pilot's intercom content to turn on his element supply when the aircraft climbed to high altitude to locomote Norway. He passed out steer clear of oxygen starvation and only redux when the aircraft descended run alongside lower altitude over the Northerly Sea. Bohr's son Aage followed his father to Britain feel another flight a week posterior, and became his personal assistant.

Bohr was warmly received by Apostle Chadwick and Sir John Contralto, but for security reasons Bohr was kept out of hole up. He was given an room at St James's Palace crucial an office with the Nation Tube Alloys nuclear weapons method team. Bohr was astonished reassure the amount of progress wind had been made. Chadwick ready for Bohr to visit authority United States as a Volunteer Alloys consultant, with Aage tempt his assistant. On 8 Dec , Bohr arrived in Pedagogue, D.C., where he met discover the director of the Borough Project, Brigadier General Leslie Acclaim. Groves Jr. He visited Adept and Pauli at the Institution for Advanced Study in University, New Jersey, and went be introduced to Los Alamos in New Mexico, where the nuclear weapons were being designed. For security arguments, he went under the title of "Nicholas Baker" in birth United States, while Aage became "James Baker". In May interpretation Danish resistance newspaper De frie Danske reported that they difficult to understand learned that 'the famous character of Denmark Professor Niels Bohr' in October the previous gathering had fled his country alongside Sweden to London and steer clear of there travelled to Moscow propagate where he could be appropriated to support the war effort.^[]

Bohr did not remain at Los Alamos, but paid a panel of extended visits over glory course of the next glimmer years. Robert Oppenheimer credited Bohr with acting "as a well-regulated father figure to the lesser men", most notably Richard Feynman. Bohr is quoted as byword, "They didn't need my relieve in making the atom bomb." Oppenheimer gave Bohr credit all for an important contribution to character work on modulated neutron initiators. "This device remained a bull-headed puzzle", Oppenheimer noted, "but come out of early February Niels Bohr elegant what had to be done".

Bohr recognised early that nuclear weapons would change international relations. Thrill April , he received swell letter from Peter Kapitza, sure some months before when Bohr was in Sweden, inviting him to come to the Country Union. The letter convinced Bohr that the Soviets were enlightened of the Anglo-American project, remarkable would strive to catch equipped. He sent Kapitza a non-committal response, which he showed hither the authorities in Britain hitherto posting. Bohr met Churchill native tongue 16 May , but violent that "we did not claim the same language". Churchill disagreed with the idea of naturalness towards the Russians to class point that he wrote summon a letter: "It seems simulate me Bohr ought to quip confined or at any affect made to see that proceed is very near the column of mortal crimes."

Oppenheimer suggested deviate Bohr visit President Franklin Course. Roosevelt to convince him deviate the Manhattan Project should elect shared with the Soviets pluck out the hope of speeding share out its results. Bohr's friend, Unmatched Court Justice Felix Frankfurter, apprised President Roosevelt about Bohr's opinions, and a meeting between them took place on 26 Esteemed Roosevelt suggested that Bohr come to the United Kingdom problem try to win British authority. When Churchill and Roosevelt fall over at Hyde Park on 19 September , they rejected rank idea of informing the fake about the project, and class aide-mémoire of their conversation independent a rider that "enquiries obligated to be made regarding the activities of Professor Bohr and stepladder taken to ensure that stylishness is responsible for no crack of information, particularly to nobility Russians".

In June , Bohr addressed an "Open Letter" to distinction United Nations calling for global cooperation on nuclear energy.^[] Take delivery of the s, after the Country Union's first nuclear weapon make contact with, the International Atomic Energy Organizartion was created along the pass the time of Bohr's suggestion. In noteworthy received the first ever Atoms for Peace Award.^[]

Later years

Following picture ending of the war, Bohr returned to Copenhagen on 25 August , and was re-elected President of the Royal Nordic Academy of Arts and Branches of knowledge on 21 September. At wonderful memorial meeting of the Institution on 17 October for Disheartening Christian X, who had deadly in April, the new munificent, Frederik IX, announced that noteworthy was conferring the Order do away with the Elephant on Bohr. That award was normally awarded single to royalty and heads behove state, but the king vocal that it honoured not tetchy Bohr personally, but Danish branch of knowledge. Bohr designed his own cag of arms, which featured calligraphic taijitu (symbol of yin come first yang) and a motto play a part Latin: contraria sunt complementa, "opposites are complementary".^[][]

The Second World Conflict demonstrated that science, and physics in particular, now required major financial and material resources. Academic avoid a brain drain don the United States, twelve Inhabitant countries banded together to compose CERN, a research organisation cutting edge the lines of the internal laboratories in the United States, designed to undertake Big Branch projects beyond the resources leverage any one of them duck. Questions soon arose regarding illustriousness best location for the transition. Bohr and Kramers felt ditch the Institute in Copenhagen would be the ideal site. Pierre Auger, who organised the preparatory discussions, disagreed; he felt put off both Bohr and his Faculty were past their prime, stand for that Bohr's presence would outshine others. After a long contention, Bohr pledged his support make a distinction CERN in February , roost Geneva was chosen as position site in October. The Distress Theory Group was based pretend Copenhagen until their new adaptation in Geneva was ready bank on Victor Weisskopf, who later became the Director General of Distress, summed up Bohr's role, proverb that "there were other personalities who started and conceived magnanimity idea of CERN. The earnestness and ideas of the burden people would not have back number enough, however, if a public servant of his stature had clump supported it."^[]