The concept of nonlocality and its role in the violation of Bell's inequalities are discussed. A weaker nonlocality is revealed in comparison with Albert Einstein's "Spooky Action at a Distance" and at the same time does not contradict the principles of the special theory of relativity (STR). A correlation statistical experiment with the violation of the Clauser—Horne—Shimony—Holt inequality in STR is described, in which weak nonlocality is manifested. The correlation in such an experiment propagates with infinite speed in the proper frame of reference of the measuring device.

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Keywords: Bell's inequalities, nonlocality, special relativity, Spooky Action at a Distance, entangled states PACS: 03.37.+p, 03.65.Ud, 03.67.Bg (all) DOI: 10.3367/UFNe.2025.08.040002 URL: https://ufn.ru/en/articles/2026/2/f/ Citation: Belinsky A V, Dzhadan I I "Nonlocality and nonseparability of quantum and relativistic systems" Phys. Usp. 69 (2) (2026) Received: 16th, June 2025, revised: 4th, August 2025, accepted: 7th, August 2025 Оригинал: Белинский А В, Джадан И И «Нелокальность и несепарабельность квантовых и релятивистских систем» УФН 196 205–211 (2026); DOI: 10.3367/UFNr.2025.08.040002