Modern physics

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As modern physics , the phase is considered in the development of physical ideas in the essential concepts of classical physics revoked or whose boundaries were made aware. Its beginning can be dated around the turn of the 19th and 20th centuries .

Essential aspects were

1. the discovery of the smallest units of matter (initially atoms ) and radiation (initially light quanta );
2. the overcoming of the determinism of the laws of nature , which more and more had to be formulated as laws of probability in order to be brought into harmony with the observations.
3. the discovery of the dual character of all physical particles and rays, in that they have both wave and particle properties ( wave-particle dualism ).

During this time, many theories of modern physics emerged that have implications for practically all subjects of physics: quantum physics and special relativity . Important early pioneers of the new concepts were

1. Max Planck (1900) with his quantum hypothesis , the basis for the development of quantum mechanics , atomic physics , nuclear physics etc .;
2. Albert Einstein (1905) with his application of the quantum hypothesis to the photo effect and the creation of the special theory of relativity , with which, among other things, the concept of aether as a carrier medium for light was abolished, a new understanding of the concept of simultaneity created, matter equated with energy (E = mc²) and the central importance of the constant speed of propagation of light was shown;
3. Niels Bohr (1913) with his application of quantum theory to atoms , which made their structure from subatomic particles theoretically accessible.

This was accompanied by important experiments, the results of which formed the basis for the new theories:

1. the Michelson-Morley experiment (1887), which showed that the speed of propagation of light is independent of direction and that the effects of a (hypothetical) aether against which the earth moves cannot be determined;
2. the discovery and research of X-rays (from 1895);
3. the discovery and research of radioactivity (from 1896);
4. the discovery and research of cathode rays (from 1869);
5. the discovery of the structure of atoms from the atomic nucleus and atomic shell (from 1911).

The term modern physics is to be seen relatively. In the meantime, some of the older theories of “modern physics” have in part just as limited validity as some of the classical theories of their time were. As far as elementary objects are concerned, contemporary physics is based on the concept of field quanta and their interaction .

literature

• Richard T. Weidner, Robert Sells: Elementare modern physics , Vieweg, Stuttgart 1982, ISBN 3-528-08415-4
• Jörn Bleck-Neuhaus: Elementary Particles: Modern Physics from Atoms to the Standard Model , Springer, Heidelberg 2010, ISBN 978-3-540-85299-5
• Romano A. Rupp, Faculty of Physics, University of Vienna: Principles of Modern Physics. Special relativity and quantum theory for teacher training candidates. July 10, 2013, archived from the original on June 13, 2015 ; accessed on August 13, 2019 .