Physics

Michel Paty

Despite its power as the conceptual basis for a huge range of physical phenomena in atomic and subatomic physics, quantum mechanics still suffers from a lack of clarity regarding the physical meaning of its fundamental theoretical concepts, such as those of quantum state and of quantum theoretical quantities or variables , dealt with by the known mathematical-theoretical rules. These concepts have generally been considered as not giving a direct description of physical systems, for they do not correspond to what is usually understood by `physical states' or `physical properties', notably characterized by definite numerical values such as those obtained from measurement. The situation has been tentatively expressed in terms of various `interpretations', conceived not only with regard to the physical meanings of mathematical quantities, but also in connection with philosophical statements about `physical reality'. The question of whether or not quantum theoretical quantities describe definite physical systems existing in nature has therefore generally been considered as beyond the possibilities of physics, because of the definitions that are commonly taken for `physical state' and `physical quantity'. We sketch the main ideas on this problem and propose a possible way out of the puzzle, in terms of an extension of the meaning given to the concepts of the physical state and physical quantity of a system, which would allow one, without any theoretical change in quantum mechanics, to speak consistently of real quantum systems as having definite physical properties .

Hisham B. Ghassib

In this paper, we argue that there are foundational dilemmas in theoretical physics related to the concept of reality and the nature of mathematics in physics. Physical theory is treated as a conceptual organism which develops under the weight of its internal contradictions. The paper discusses in depth the problem of objective reality in physics and its relation to scientific practice. Then, it explores the problematic relation between physical meaning and mathematics in modern physical theory, followed by a discussion of the trend of contemporary physics to replace physical principles with pure mathematical principles. Finally, it discusses the problem of logical coherence in modern physical theory. The paper emphasizes the importance of resolving these dilemmas to the proper practice of theoretical physics.

Vera M. Schäfer

Anirudh Singh

This chapter critically examines the criteria that the discipline of physics must satisfy to be able to explain the behavior of the physical world. These criteria may be divided into the primary, secondary, and fundamental requirements of physics. The primary requirements include the need for physics to explain the physical world at all scales and time, to acknowledge that physics describes the real world and is dependent on observers for its measurement and interpretation. The indeterminacy inherent in the quantum mechanical framework is examined in this chapter, and it is concluded that this does not in any way affect the law of causality that forms a basic tenet of classical physics. All requirements of physics are subject to the fundamental requirement of physics, which states that the laws of physics are determined exclusively by the total content of the universe.