Brief attempt about quantum and wholeness – The birth of quantum mechanics

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It required a substantial extension of physics to recognize the ground on which these probability functions take place and that we are actually dealing with a fundamental unit of the universe.

The problem that required this solution was how an atom emits light when its electrons fall back from an excited state to a ground state. Einstein proposed a process he called spontaneous emission in 1916 but found no way to calculate it. In 1927, Paul Dirac produced the first nearly complete theory describing the electromagnetic field and electrically charged particles (primarily electrons) and gave this area of science the new term quantum electrodynamics. It was able to model the processes in question, in which electrons make quantum jumps and emit or absorb photons. Thus, the quantization of each oscillation mode of an electromagnetic field became evident, providing a solid mathematical foundation for Einstein’s concept of the photon.

But since photons move at the speed of light, normal quantum mechanics cannot even provide an approximate description of this process. It does not consider the special theory of relativity, which must always come into play when velocities close to that of light are reached. Thus, the world was still thought of as consisting of two completely different components – particles and fields – each to be described in a different way by the terms of quantum mechanics. We understood particles like electrons and protons to be fundamental, quasi-eternal entities. On the other hand, we assumed that photons were merely manifestations of their underlying entity, the quantized electromagnetic field, capable of creation and destruction at will.

We needed a complete relativistic quantum theory of the electromagnetic field to resolve this highly unsatisfactory dualism.

The decisive steps in this direction followed in 1928 from Pascual Jordan, Wolfgang Pauli and Paul Dirac. Jordan and Pauli demonstrated through a mathematical process known as coordinate transformation that special relativity predicts the behavior of quantum fields. Dirac produced the Dirac equation, named after him, which allowed quantum objects, such as electrons, to be described fully in accordance with special relativity for the first time. – This intellectual feat elevated him to the same level as Newton, Maxwell, and Einstein! Then, in 1929, Werner Heisenberg and Wolfgang Pauli were able to present the first general quantum field theory. They demonstrated that we can understand matter particles as the quanta, or discrete stages of change, of different fields. Just as the photon is the quantum of the electromagnetic field. Each elementary particle was thus attributed its own field.

Thus, the inhabitants of the universe were understood as an extensive set of different fields – an electron field, a proton field, an electromagnetic field – and particles were reduced to phenomena that were causally caused but had no significant effect themselves. This view is the central dogma of quantum field theory: reality consists of a set of fields that obey the rules of special relativity and quantum mechanics. Everything else arises as a consequence of the quantum dynamics of these fields.

„Quantum physics reveals a fundamental unity of the universe. It shows us that we cannot divide the world into independently existing smallest units. When we penetrate into the depths of matter, nature does not show us isolated basic building blocks but rather appears as an intricate web of connections between the various parts of the whole.“
Fritjof Capra, Das Tao der Physik (2)

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