After a brief introduction about the quantum twentieth century, and about the year of 2025 as the international year of quantum theory and quantum technology, according to the United Nations resolution, we discuss the impact of the former and its two key narratives – the observer and the measurement—on quantum chemistry and its core concepts: the bond, localization and delocalization. We demonstrate that the latter two took the origin in the old quantum theory that started in 1900, in M. Planck’s hands. The above narratives were marked by J. Bell in his work “Against ‘measurement”, where he mentioned P.A.M. Dirac as the most distinguished of ‘why bother?’ers since P. Dirac in his paper “The Evolution of the Physicist’s Picture of Nature” considered the difficulties of quantum mechanics and divided them into two classes. Into the first one, he particularly attributed the problems of ‘observer’ and ‘measurement’ and suggested that these problems should be left for later. It is precisely the latter that is the goal of this work that splits into two sub-goals. The first is to construct a logically consistent chain of reasoning to link to the above narratives. The second is to propose a new scheme of quantum measurement based on the concept that the state of a quantum system necessarily changes under measurement, that put forward in the works of Fock, von Neumann and De Broglie, (In fact, this issue has recently been discussed in Quora (<a href="https://www.quora.com/">https://www.quora.com/</a>; Mark John Fernee. “In quantum mechanics, is it true that the properties of a system are affected by the action of observation, or is it just another popular misdirection?” Speaking rigorously, the word ‘observation’ was corrected in the next lines as follows: “Yes, it is called measurement back-action. Ultimately, quantum theory is formulated in terms of interactions. An “observation” therefore must comprise some form of interaction. Any interaction changes the state of the system under consideration. There is no way around this. That said, there are caveats. If you search, you might come across so-called interaction-free measurements. These are a type of measurement that draws an inference from not detecting something, in a sense. The Elitzur-Vaidman bomb sensor is a well-known example of such measurements. In addition, there are also weak measurements, which are designed to minimally perturb the system under study.The bottom line is that there are no passive measurements in quantum theory. If you want any information about a system, you must interact with it.”) and many others and that aims to measure quantum chemical localization and delocalization patterns.

On measuring localization and delocalization patterns in molecules

期刊论文
发表日期：

2026年5月5日

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Eugene S. Kryachko

摘要

After a brief introduction about the quantum twentieth century, and about the year of 2025 as the international year of quantum theory and quantum technology, according to the United Nations resolution, we discuss the impact of the former and its two key narratives – the observer and the measurement—on quantum chemistry and its core concepts: the bond, localization and delocalization. We demonstrate that the latter two took the origin in the old quantum theory that started in 1900, in M. Planck’s hands. The above narratives were marked by J. Bell in his work “Against ‘measurement”, where he mentioned P.A.M. Dirac as the most distinguished of ‘why bother?’ers since P. Dirac in his paper “The Evolution of the Physicist’s Picture of Nature” considered the difficulties of quantum mechanics and divided them into two classes. Into the first one, he particularly attributed the problems of ‘observer’ and ‘measurement’ and suggested that these problems should be left for later. It is precisely the latter that is the goal of this work that splits into two sub-goals. The first is to construct a logically consistent chain of reasoning to link to the above narratives. The second is to propose a new scheme of quantum measurement based on the concept that the state of a quantum system necessarily changes under measurement, that put forward in the works of Fock, von Neumann and De Broglie, (In fact, this issue has recently been discussed in Quora (https://www.quora.com/; Mark John Fernee. “In quantum mechanics, is it true that the properties of a system are affected by the action of observation, or is it just another popular misdirection?” Speaking rigorously, the word ‘observation’ was corrected in the next lines as follows: “Yes, it is called measurement back-action. Ultimately, quantum theory is formulated in terms of interactions. An “observation” therefore must comprise some form of interaction. Any interaction changes the state of the system under consideration. There is no way around this. That said, there are caveats. If you search, you might come across so-called interaction-free measurements. These are a type of measurement that draws an inference from not detecting something, in a sense. The Elitzur-Vaidman bomb sensor is a well-known example of such measurements. In addition, there are also weak measurements, which are designed to minimally perturb the system under study.The bottom line is that there are no passive measurements in quantum theory. If you want any information about a system, you must interact with it.”) and many others and that aims to measure quantum chemical localization and delocalization patterns.