The Sagnac effect is usually considered as being a relativistic effect produced in an interferometer when the device is rotating. General relativistic explanations are known and already widely explained in many papers. Such general relativistic approaches are founded on Einstein’s equivalence principle (EEP), which states the equivalence between the gravitational “force” and the pseudo-force experienced by an observer in a non-inertial frame of reference, included a rotating observer. Typically, the authors consider the so-called Langevin-Landau-Lifschitz metric and the path of light is determined by null geodesics. This approach partially hides the physical meaning of the effect. It seems indeed that the light speed varies by $$c\pm \omega r$$ c ± ω r in one or the other direction around the disk. In this paper, a slightly different general relativistic approach will be used. The different “gravitational field” acting on the beam splitter and on the two rays of light is analyzed. This different approach permits a better understanding of the physical meaning of the Sagnac effect.

This paper explores an event-based version of quantum mechanics which differs from the commonly accepted one, even though the usual elements of quantum formalism, e.g., the Hilbert space, are maintained. This version introduces as primary element the occurrence of micro-events induced by usual physical (mechanical, electromagnetic and so on) interactions. These micro-events correspond to state reductions and are identified with quantum jumps, already introduced by Bohr in his atomic model and experimentally well established today. Macroscopic bodies are defined as clusters of jumps; the emergence of classicality thus becomes understandable and time honoured paradoxes can be solved. In particular, we discuss the cat paradox in this context. Quantum jumps are described as temporal localizations of physical quantities; if the information associated with these localizations has to be finite, two time scales spontaneously appear: an upper cosmological scale and a lower scale of elementary “particles”. This allows the interpretation of the Bekenstein limit like a particular informational constraint on the manifestation of a micro-event in the cosmos it belongs. The topic appears relevant in relation to recent discussions on possible spatiotemporal constraints on quantum computing.

We propose here a formal approach to study collective behaviors intended as coherent sequences of spatial configurations, adopted by agents through various corresponding structures over time. Multiple, simultaneous structures over time and their sequences are called Meta-Structures and establish sequences of spatial configurations considered as emergent on the basis of coherent criteria chosen and detected by an observer. This coherence is represented by patterns of values of the proper mesoscopic variables adopted, i.e., meta-structural properties. We introduce a formal tool, i.e., the family of mesoscopic general vectors, defined by the observer, able to detect coherent behaviors like ergodic or quasi-ergodic ones. Such approach aims to provide a general framework to study intrinsically stochastic processes where the “universal evolution laws” fail. However, at the same, the system is structured enough to show significant clusters of collective behaviors “invisible to” simple statistics.

In this contribution, we consider Collective Behaviours as coherent sequences of spatial configurations adopted by agents interacting through corresponding different structures over time. The approach relates to the one adopted time ago when introducing the concept of multiple systems arising when each composing element can play simultaneously or sequentially different roles. In this case, each element simultaneously or sequentially belongs to different systems. Multiple structures over time and their sequences are considered as meta-structures establishing coherent sequences of different systems. They are intended as coherent when acquiring emergent properties. Such coherence is considered here as being represented by the values adopted by suitable mesoscopic variables and their properties, i.e. meta-structural properties, allowing the researcher to (a) recognise a phenomenon as emergent, (b) induce emergence of collective behaviour in populations of elements collectively interacting, (c) act on collective emergent phenomena with the purpose to change, regulate and maintain acquired properties and (d) merge different collective emergent phenomena. We introduce a formal tool, i.e. the mesoscopic general vector to represent the adoption, over time, of mesoscopic properties by collectively interacting elements. We mention future experimental lines of activities, future lines of research and possible applications.