What is the quantum theory of radiation

Quantum theory

Quantum theory explains radioactivity

Nuclear physics, especially the radioactivity, was fertilized by quantum theory. So describes the Tunnel effect the Alpha decay. Here (positively charged) α-particles (helium atomic nuclei) can tunnel through the Coulomb wall of the (also positively charged) atomic nucleus, because the wave function or the probability of the α-particle being outside the nucleus is small, but finite Has value.
The Beta decay is explained by the theory of weak interaction, in that the charged exchange particles (W particles) of the weak theory change the quark content of protons or neutrons.
Finally, the emission of high-energy light quanta, the Gamma radiation, understandable in gamma decay, because highly excited daughter nuclei from radioactive (alpha or beta) decays 'de-energize' themselves into energetically lower states of the atomic nucleus. Not only the states of the electrons in the shells of the atom are described in quantum theory, but also those of the nucleons (protons and neutrons) in the atomic nucleus!

famous quantum physicist

The quantum theory of the first half of the 20th century had the following important pioneers (all except Sommerfeld Nobel Prize winners) including work areas:

  • the German Arnold Sommerfeld (1868 - 1951), Bohr-Sommerfeld model of the atom, spectral lines, fine structure constant;
  • the New Zealander Ernest Rutherford (1871 - 1937), Rutherford's atomic model, α-decay, scattering;
  • the Dane Niels Bohr (1885 - 1962), Bohr-Sommerfeld model of the atom, Bohr's postulates;
  • the Austrian Erwin Schrödinger (1887 - 1961), wave mechanics, Schrödinger equation as a fundamental equation of motion in quantum mechanics;
  • the German Max Born (1882-1970), Copenhagen Interpretation, Quantum Statistics, Scatter Theory;
  • the Frenchman Louis de Broglie (1892 - 1987), wave-particle dualism, matter waves;
  • the Austrian Wolfgang Pauli (1900 - 1958), Pauli principle, spin statistics theorem, prediction of neutrinos;
  • the German Werner Heisenberg (1901 - 1976), Heisenberg uncertainty principle, matrix mechanics;
  • the Italian Enrico Fermi (1901 - 1954), Fermi statistics (fermions, Fermi energy), nuclear fission, neutrons;
  • the Briton Paul Dirac (1902 - 1984), Dirac theory of the electron, relativistic quantum mechanics, antimatter;

From QM to QFT

The areas of these protagonists are subsumed under Quantum mechanics (QM). A further area of ​​quantum theory, which represents a modern approach, must be distinguished from this, namely the Quantum field theory (QFT). The QFT systematically examines each of the four fundamental natural forces (electromagnetism, weak interaction, strong interaction, gravitation) and tries to unite them (see also Standard Model and GUT). The unification of all interactions into one Elemental force must have prevailed at high temperatures in the early universe, only fractions of a second after the Big Bang. This state of high symmetry disintegrated through symmetry breaking until the current state of our world was reached.

crazy quantum world

Quantum theory reveals a number of seemingly strange principles (fuzziness, probability wave, duality) and phenomena (energy quantum, quantum vacuum, tunnel effect, superfluids, Casimir effect), which seem completely removed from our everyday world and the conception that is shaped by classical physics. Nevertheless, or precisely because of this, it is very successful and currently the only theory in the atomic or subatomic area that provides an adequate and experimentally verifiable description. In this respect, from the epistemological standpoint, quantum theory can be described as a theory that manifests itself in many ways proven Has. The difficulties of quantum theory lie in its lack of visualization, which requires a high degree of abstraction, and in the fact that it is conceptually different. But this will revolutionize our understanding of what nature is! A objective observer gets lost with quantum theory! The uncertainty principle teaches us that observation already influences the observed system and changes its state. It is vividly clear, because Observe means that we need other test particles (e.g. photons, i.e. light) that interact with the (subatomic) sample, e.g. are backscattered. The test particles tell the experimenter by their properties when they reach the observer what state the sample is in. The crux in the atomic and subatomic realm is just that the test particles affect the sample! This interaction between 'observing and observed particles' ultimately leads to blurring.

Movement is a sequence of creation and annihilation

Another fact is that the classical, well-defined path of a particle Not exists. you appears us just like that! In the quantum-theoretical picture, the particle that moves on a trajectory is generated at one place and time in space, destroyed and generated again at another, etc. Since this takes place on the quantum level, which cannot be observed macroscopically, appears it is as if a particle were traveling along a path. But in truth there is a constant coming and going in the quantum world, also in real nature, which is mathematically also described with creation and annihilation operators. These operators are sufficient canonical commutation relations: Commutators for the bosons andAnti-commutators at the fermions. This formulation is the basis of the Second quantization.

Transition to quantum cosmology

The concepts of second quantization were also carried over to cosmology. This discipline is called quantum cosmology. The existence of many parallel universes is an inevitable consequence of this approach. In quantum cosmology one speaks of one Multiverse. This research is also speculative and pure theory. So far there has been no evidence from astronomical observations to support quantum cosmological scenarios.