Werner Karl Heisenberg

Werner Karl Heisenberg ( Würzburg , December 5 , 1901 – Munich , February 1 , 1976 ) was a German physicist, Nobel Prize in Physics in 1932 for the creation of quantum mechanics , the use of which has led, among other things, to the discovery of allotropic forms of hydrogen .

Summary

[ disguise ]

• 1 Biographical summary
  • 1 Youth
  • 2 Maturity
• 2 Contributions
• 3 Works
  • 1 Uncertainty principle
  • 2 Fragment of Dialogues on Atomic Physics
• 4 References
• 5 Sources

Biographical summary

In September 1906, shortly before turning five years old, Heisenberg began his primary education at a school in Würzburg . He spent three years at that school, until his father was appointed, in 1909, professor of Greek at the University of München . In June 1910, a few months after his father assumed his new teaching position, Werner and the rest of the family moved to Munich. There, starting in September of that year, Werner attended classes at the Elisabethenschule school. In 1911, he began to study at the Maximilian Gymnasium in München, where his maternal grandfather was director.

Youth

In 1923 he was an assistant to the German physicist Max Born at the University of Göttingen , and from 1924 to 1927 he held a Rockefeller Foundation fellowship to work with the Danish physicist Niels Bohr at the University of Copenhagen . In 1927 he was appointed professor of theoretical physics at the University of Leipzig .

Maturity

He was a professor at the universities of Berlin ( 1941 – 1945 ), Göttingen ( 1946 – 1958 ) and Munich (1958-1976 ) . In 1941 he became director of the Kaiser Wilhelm Institute for Physical Chemistry (which in 1946 was renamed the Max Planck Institute for Physics).

Contributions

Heisenberg, one of the world’s first theoretical physicists, made his most important contributions to the theory of atomic structure. In 1925 he began to develop a system of quantum mechanics, called matrix mechanics, in which the mathematical formulation was based on the frequencies and amplitudes of the radiation absorbed and emitted by the atom and on the energy levels of the atomic system. The uncertainty principle played an important role in the development of quantum mechanics and the progress of modern philosophical thought.

Plays

• Die physikalischen Prinzipien del Quantentheori(The Physical Principles of Quantum Theory, 1930 )
• Cosmic Radiation(1946)
• Physics and Philosophy(1958)
• Introduction to the Unified Theory of Elementary Particles( 1967 ).

Begining of uncertainty

In quantum mechanics, a principle that states that it is impossible to simultaneously accurately measure the position and linear momentum of a particle, such as an electron. The principle, also known as the principle of indeterminacy, also states that if one of the quantities is determined more precisely, precision will be lost in the measurement of the other, and that the product of both uncertainties can never be less than Planck’s constant. named after the German physicist Max Planck. The uncertainty is very small, and is negligible in classical mechanics. On the other hand, in quantum mechanics the precise predictions of classical mechanics are replaced by probability calculations.

The uncertainty principle was formulated in 1927 and was of great importance for the development of quantum mechanics. The philosophical implications of indeterminacy created a strong current of mysticism among some scientists, who interpreted the concept as overturning the traditional idea of ​​cause and effect. Others, including Albert Einstein , considered that the uncertainty associated with observation does not contradict the existence of laws that govern the behavior of particles, nor the ability of scientists to discover these laws.

Fragment of Dialogues on Atomic Physics

In Dialogues on Atomic Physics, W. Heisenberg, Nobel Prize winner in Physics in 1932 , develops the atomic physics of his time, as he lived it. This fragment reproduces one of the dialogues that the author had with Lord Rutherford and Niels Bohr about the structure of atomic nuclei and the possibilities of atomic technology.

Werner Karl Heisenberg: In this cozy house I spent several weeks meeting the Bohr family. Also around that time the English physicist Lord Rutherford – later called the father of modern atomic physics – spent a short vacation in Copenhagen at Bohr’s house. It was then that the three of us would go for a walk in the park, exchanging our opinions on the most recent experiments or on the structure of atomic nuclei. Here is one of those dialogues:

Lord Rutherford: What happens when we build increasingly powerful high-voltage devices, or other accelerators, and bombard heavier atomic nuclei with protons of even higher energy and speed? Will the fast projectile simply pass through the atomic nucleus, perhaps without causing major damage, or will it be stopped in the atomic nucleus, so that all its kinetic energy is transmitted to the nucleus? If the reciprocal interactions between the nuclear elements are as important as Niels thinks, the projectile will become embedded. But if the protons and neutrons move almost independently within the atomic nucleus, without strongly influencing each other, then the projectile could perhaps pass through the nucleus, without causing major disruption.

Niels: I would certainly believe that, in general, the projectile stops in the atomic nucleus and that its kinetic energy is ultimately distributed uniformly, in some way, among all the nuclear elements, since the interaction is so very powerful. With such a collision, the atomic nucleus is heated, and the degree of heating can be calculated by the specific heat of the nuclear matter and by the energy contained in the projectile. What happens next can best be described as a partial vaporization of the atomic nucleus. This means that some particles on the surface will sometimes be charged with such high energy that they will leave the atomic nucleus. But what do you say to this?

The question was addressed to Heisenberg: All in all, I would believe the same thing – I responded – although it does not seem to fully conform to the idea we have in Leipzig that the nuclear elements evolve almost freely within the nucleus. But a very fast particle that penetrates the nucleus is sure to suffer several collisions due to the large interaction forces, and thereby lose its energy. For a slower particle that moves within the atomic nucleus with only small energy, things may present themselves differently since the wave nature of the particles then comes into play and the number of possible energy transfers is reduced. In such a case, not taking the interaction into account may even be an acceptable approximation. But all this will have to be calculated, since we currently know a lot about the atomic nucleus. I am going to dedicate myself in Leipzig to this calculation.

But I would now like to ask a counter-question: Is it possible to think that with increasingly larger accelerators we will finally reach a technical application of nuclear physics, such that, for example, large quantities of new chemical elements are artificially produced or also the binding energy of the nuclei, in a similar way to how chemical binding energy is used in combustion? I remember that there is a futuristic English novel in which a physicist invents for his country, in moments of most acute political tension, an atomic bomb, with which he eliminates all political difficulties as a ‘deus ex machina’. It is, of course, a dream. However, in a more serious tone, the physicist-chemist Nernst once stated in Berlin that the Earth is, in reality, a keg of gunpowder, which only lacks the match to make our planet fly through the sky. airs. This is undoubtedly true, since, if it were possible to fuse, for example, four atomic nuclei of hydrogen within sea water and transform them into an atomic nucleus of ice, such enormous energy would be released with them that the comparison of the gunpowder keg would serve only as a laughable imitation.

Niels: No, such considerations have so far not been definitively conclusive. The most decisive difference between chemistry and nuclear physics is that, in general, chemical processes propagate in the respective substance to the greatest number of molecules – this is the case, for example, of gunpowder – while in Nuclear physics we can only experiment with a small number of atomic nuclei. This will not become fundamentally different even with larger accelerators. The number of processes developed in a chemical experiment with respect to the number of processes caused until now by physical-nuclear experiments is in a similar proportion, so to speak, to that presented by the diameter of our planetary system with respect to the diameter of a stone. rolled; and it wouldn’t mean much more if we replaced the boulder with a block of rock.

Things would, naturally, be very different if a piece of matter could be placed at such high temperatures that the energy of each of the particles would be sufficient to overcome the forces of repulsion between the atomic nuclei and if the density of the matter was could be kept so high at the same time that the collisions were not too rare. But to do this we would have to reach temperatures of, let’s say, a billion degrees, and with such temperatures there are, of course, no containers that can enclose the matter, since they would have volatilized long before.

Lord Rutherford: Until now it has never been said that energy could be obtained from the processes of atomic nuclei. I admit that in the fusion of a proton or a neutron with an atomic nucleus, energy is actually released within each singular process. But to make such a process take place, much more energy must be expended; for example, to achieve the acceleration of many protons, most of which do not collide with anything. Most of this energy is practically lost in the form of heat movement. Energetically, therefore, experimenting with atomic nuclei is, until now, a pure loss business. Talking about a technical use of atomic-nuclear energy is simply nonsense.

With this opinion everyone soon agreed. No one foresaw then that, a few years later, the discovery of uranium fission by Otto Hahn would radically change the situation.