What is Time in Modern Physics?
The problem of time is not an entirely physical problem. Physics itself does not contain a "time theory". That is particularly true in the sense that physics has not made any direct attempts to find the natural-science definition of the notion of time. Nevertheless, the concept of time emerges in science one way or another and still requires an explanation. Time fulfills an important role in the physics of XX and XXI centuries, though often a hidden one. Such a statement could be applied to both theories of macrocosm and microcosm. In the theory of relativity, time has been established as a secondary feature, a derivative of velocity and mass. However, it exists (although, as an illusion) and yet evokes the need of its philosophical interpretation. In quantum field theory time also (though implicitly) occurs according to the interpretation of the experiment results - for example, “where the particle was before its observation”. Such “before”-cases indicate the very presence of time (more precisely, the observer`s perception of its presence). Further theories, which have been the attempts to solve the problem of incompatibility of general relativity theory and quantum mechanics, such as the theory of loop quantum gravity, superstring theory, Shape Dynamics and others, also mention the concept of time. Time fulfills there a definite role and again evokes the question of its explanation in the frameworks of these theories. Most importantly, to find an exact meaning of this “time” term used here. This article deals with the problem of time in the context of several theories of modern physics. In particular, it attempts to give a definition of the term of time in relation to the philosophy of physics (physics itself does not characterize it). Such a task formulation has its relevance and novelty due to the facts that the discourse on the nature of time is still stipulated by Zeno`s paradoxes, and the philosophy of science uses the obsolete vocabulary while describing the term. However, evidence suggests that modern physics has developed the new rules, or to be more precise, has stated the new principles, which the philosophy of science can not take into consideration without changing its vocabulary (the last also involves the modernization of intellectual intuition).