Danish physicist Bor Niels: biography, discoveries

Niels Bohr is a Danish physicist and public figure, one of the founders of physics in the modern form. He was the founder and leader of the Copenhagen Institute of Theoretical Physics, the creator of the world scientific school, and also a foreign member of the Academy of Sciences of the USSR. This article will examine the life story of Niels Bohr and his main achievements.

Merit

The Danish Physicist Bohr Nils founded the theory of the atom, which is based on the planetary model of the atom, the quantum delineations and the postulates offered to them personally. In addition, Bohr was remembered for important work on the theory of the atomic nucleus, nuclear reactions and metals. He was one of the participants in the creation of quantum mechanics. In addition to working in the field of physics, Bohr has a number of works on philosophy and natural science. The scientist actively struggled with the atomic threat. In 1922 he was awarded the Nobel Prize.

Childhood

The future scientist Niels Bohr was born in Copenhagen on October 7, 1885. His father, Christian, was a professor of physiology at a local university, and Ellen's mother came from a wealthy Jewish family. Nils had a younger brother Harald. Parents tried to make their sons' childhood happy and rich. The positive influence of the family, and in particular of the mother, played a crucial role in the development of their spiritual qualities.

Education

Primary education Bohr got in the Gammelholm school. In school years, he was fond of football, and later - skiing and sailing. At twenty-three, Bohr became a graduate of Copenhagen University, in which he was considered an unusually gifted research physicist. For the diploma project dedicated to determining the surface tension of water by means of vibrations of a water jet, Niels was awarded a gold medal from the Royal Danish Academy of Sciences. Having received education, the beginning physicist Bohr Niels remained at the university. There he carried out a number of important studies. One of them was devoted to the classical electronic theory of metals and formed the basis of Bohr's doctoral dissertation.

Non-standard thinking

One day, the president of the Royal Academy, Ernest Rutherford, asked for help from a colleague from the University of Copenhagen. The latter intended to give his student the lowest score, while he believed that he deserved to be rated "excellent." Both parties to the dispute agreed to rely on the opinion of a third party, an arbitrator, who became Rutherford. According to the exam questions, the student had to explain how using a barometer can determine the height of the building.

The student replied that for this you need to tie the barometer to a long rope, climb up to the roof of the building, lower it to the ground and measure the length of the rope that went down. On the one hand, the answer was absolutely correct and complete, but on the other hand it had little in common with physics. Then Rutherford suggested that the student once again try to answer. He gave him six minutes, and warned that the answer should illustrate the understanding of physical laws. Five minutes later, when he heard from the student that he was choosing the best of several solutions, Rutherford asked him to answer ahead of schedule. At this time the student offered to climb up from the barometer to the roof, drop it down, measure the time of the fall and, using a special formula, find out the height. This answer satisfied the teacher, but he and Rutherford could not deny themselves the pleasure of listening to the other versions of the student.

The next method was based on measuring the height of the shadow of the barometer and the height of the shadow of the building, with the subsequent resolution of the proportion. This option was liked by Rutherford, and he enthusiastically asked the student to cover the remaining ways. Then the student offered him the simplest option. It was necessary simply to apply the barometer to the wall of the building and make notes, and then count the number of marks and multiply them by the length of the barometer. The student believed that such an obvious answer can not be overlooked.

In order not to be seen in the eyes of scientists as a joker, the student offered the most sophisticated option. Having tied a string to the barometer, he told us, it is necessary to swing it at the base of the building and on its roof, having measured the magnitude of gravity. From the difference between the received data, if desired, you can find out the height. In addition, swinging the pendulum on the cord from the roof of the building, you can determine the height of the precession period.

Finally, the student offered to find the manager of the building and in exchange for a wonderful barometer to find out from him the height. Rutherford asked whether the student really does not know the generally accepted solution to the problem. He did not hide what he knew, but admitted that he was fed up with the teachers' imposition of his way of thinking at wards, at school and college, and rejection of non-standard solutions. As you might have guessed, this student was Niels Bohr.

Moving to England

After working at the university for three years, Bor moved to England. The first year he worked at Cambridge at Joseph Thomson, then moved to Ernest Rutherford in Manchester. At that time, Rutherford's laboratory was considered the most outstanding. Last time, experiments were conducted in it, which gave rise to the discovery of the planetary model of the atom. More precisely, the model was still at the stage of becoming.

Experiments on the passage of alpha particles through the foil allowed Rutherford to realize that in the center of the atom there is a small charged nucleus, on which hardly the entire mass of the atom, and around it are located light electrons. Since the atom is electrically neutral, the sum of the electron charges must equal the nuclear charge modulus. The conclusion that the nuclear charge is a multiple of the electron charge was central to this study, but so far it remained unclear. But the isotopes were discovered - substances having the same chemical properties, but different atomic mass.

Atomic number of elements. The law of displacement

Working in the laboratory of Rutherford, Bohr realized that the chemical properties depend on the number of electrons in the atom, that is, on its charge, rather than mass, which explains the existence of isotopes. This was the first important achievement of Bohr in this laboratory. Since the alpha particle is a helium nucleus with a charge of +2, with alpha decay (the particle emitted from the nucleus), the "daughter" element in the periodic table should be placed to the left of two cells than the "mother", and in beta decay (the electron flies out From the nucleus) to the right of one cell. Thus, the "law of radioactive displacements" was formed. Then the Danish physicist made a series of more important discoveries that concerned the very model of the atom.

The Rutherford-Bohr model

This model is also called planetary, because in it the electrons revolve around the nucleus just like the planets around the Sun. Such a model had a number of problems. The fact is that the atom in it was catastrophically unstable, and lost energy for a hundred millionth of a second. In reality, this did not happen. The problem appeared to be unsolvable and required a radically new approach. Here, the Danish physicist Bor Niels showed himself.

Bohr suggested that, contrary to the laws of electrodynamics and mechanics, there are orbits in atoms, moving along which electrons do not radiate. The orbit is stable if the angular momentum of the electron located on it is equal to half the Planck constant. Radiation occurs, but only at the moment of transition of an electron from one orbit to another. All the energy that is released is carried away by a quantum of radiation. Such a quantum has an energy equal to the product of the rotational frequency by the Planck constant, or the difference between the initial and final electron energies. Thus, Bohr combined the achievements of Rutherford and the idea of quanta, which was proposed by Max Planck in 1900. Such unification contradicted all the provisions of the traditional theory, and at the same time, did not reject it completely. The electron was considered as a material point that moves according to the classical laws of mechanics, but only those orbits that fulfill the "quantization conditions" are "resolved". On such orbits, the electron energies are inversely proportional to the squares of the orbit numbers.

The derivation from the "frequency rule"

Relying on the "frequency rule", Bohr concluded that the radiation frequencies are proportional to the difference between the inverse squares of the integers. Previously, this pattern was established by spectroscopists, but did not find a theoretical explanation. Niels Bohr's theory made it possible to explain the spectrum of not only hydrogen (the simplest of atoms), but also helium, including ionized. The scientist illustrated the influence of the nuclear shift and predicted how electronic shells are filled, which made it possible to reveal the physical nature of the periodicity of the elements of the Mendeleyev system. For these developments, in 1922 Bohr was awarded the Nobel Prize.

The Bora Institute

Upon completion of work at Rutherford already recognized physicist Bo Nils returned to his homeland, where he was invited in 1916 by a professor at the University of Copenhagen. Two years later he became a member of the Royal Danish Society (in 1939, the scientist headed him).

In 1920, Bohr founded the Institute of Theoretical Physics and became its leader. The authorities of Copenhagen, in recognition of the achievements of the physicist, provided him with the building of the historic "House of the Pivovar" for the institute. The Institute met all expectations, playing an outstanding role in the development of quantum physics. It is worth noting that the defining qualities in this were the personal qualities of Bohr. He surrounded himself with talented collaborators and students, the boundaries between which were often invisible. The Institute of Bora was international, it sought to fall from everywhere. Among the famous natives of the Bohr school can be identified: F. Bloch, V. Weisskopf, H. Casimir, O. Bohr, L. Landau, J. Wheeler and many others.

To Bohr, the German scientist Verne Heisenberg came not once. At a time when the "principle of uncertainty" was being created, Erwin Schrödinger, who was a supporter of the purely wave point of view , was discussing with Bohr. In the former "House of the Pivovar" the foundation of a qualitatively new physics of the twentieth century was formed, one of the key figures of which was Niels Bohr.

The model of the atom, proposed by the Danish scientist and his mentor Rutherford, was inconsistent. It combined the postulates of classical theory and hypotheses, which obviously contradict it. In order to eliminate these contradictions, it was necessary to radically revise the main theses of the theory. In this direction, Bohr's direct services, his authority in the scientific community, and his personal influence played an important role. The works of Niels Bohr showed that the approach, which is successfully applied to the "world of big things", and he became one of the founders of this approach, does not approach the physical picture of the microworld. The scientist introduced such concepts as "uncontrolled influence of measuring procedures" and "additional values".

Copenhagen quantum theory

The name of the Danish scientist is related to the probabilistic (also Copenhagen) interpretation of the quantum theory, as well as the study of its numerous "paradoxes". An important role here was played by Bohr's discussion with Albert Einstein, who did not like the quantum physics of Bohr in probabilistic interpretation. The "correspondence principle", formulated by the Danish scientist, played an important role in understanding the laws of the microworld and their interaction with classical (non-quantum) physics.

Nuclear topics

Having begun to study the physics of the nucleus even at Rutherford, Bohr devoted much attention to nuclear topics. He proposed in 1936 the theory of a compound nucleus, which soon spawned a drip model, which played a significant role in the study of nuclear fission. In particular, Bohr has a prediction of spontaneous fission of uranium nuclei.

When the fascists captured Denmark, the scientist was secretly brought to England, and then to America, where he worked with his son Oge on the Manhattan project in Los Alamos. In the postwar years Bohr spent a lot of time on issues of control over nuclear weapons and the peaceful use of atoms. He took part in the creation of the center for nuclear research in Europe and even addressed his ideas to the UN. Proceeding from the fact that Bohr did not refuse to discuss certain aspects of the "nuclear project" with Soviet physicists, he considered dangerous the monopoly possession of atomic weapons.

Other areas of knowledge

In addition, Nils Bohr, whose biography is coming to an end, was also interested in issues of contiguous with physics, in particular biology. He was also interested in the philosophy of natural science.

An outstanding Danish scientist died of a heart attack on October 18, 1962 in Copenhagen.

Conclusion

Nils Bohr, whose discoveries, of course, changed physics, enjoyed a huge scientific and moral authority. Communication with him, even fleeting, made an indelible impression on the interlocutors. According to Bor's speech and letter it was clear that he carefully selects words in order to illustrate his thoughts as accurately as possible. Russian physicist Vitaly Ginzburg called Bora incredibly delicate and wise.