Historical Epistemology of the Final Theory Program

In 1916, Albert Einstein suggested for the first time that it would be necessary to merge his newly constructed general theory of relativity and the emerging quantum theory. 100 years later, this challenge remains unanswered, and the problem of constructing a theory of “quantum gravity” (as such a hypothetical merging came to be known) has become synonymous with physicists’ search for a final, fundamental theory. The Max Planck Research Group “Historical Epistemology of the Final Theory Program”, based at the Max Planck Institute for the History of Science in Berlin, reflects on and evaluates this century-long search using the methods of historical epistemology. It is the explicit aim of the group to conduct historical research that connects directly to contemporary physical research, providing a novel, historico-critical view of its status and prospects. To this end the group is working in collaboration with the Max Planck Institute for Gravitational Physics in Potsdam.

The group’s study of the final theory program is guided and structured by three main investigations, one dealing with the historically singular nature of the final theory program itself, the other two dealing with distinct opposition movements that emerged in the course of the second half of the 20th century:

(1) Post-Empirical Physics: It is often remarked that the current search for a final theory, in particular in the form of string theory, has severed all contacts with experiment. The group pursues the question not only of how this came to be, but, even more importantly, of how this was even possible. It investigates how the major knowledge systems established in the early 20th century, general relativity and quantum theory, were used as a reservoir for the construction of new theories, free from empirical input, and why and how physicists pursued this path.

(2) Mathematical Physics: The presence of the final theory program has enabled the practice of postponing the discussion of foundational difficulties in contemporary theoretical physics to the future, when the final theory will be available to answer those questions. The group investigates how this practice arose and its implications for the methodology and standards of theoretical physics. It further investigates how the opposition to this practice led to the establishment of new subdisciplines of physics, dealing explicitly with the unresolved conceptual (foundations of quantum mechanics) and formal (mathematical physics, in particular axiomatic quantum field theory) difficulties of contemporary theoretical physics.

(3) Anti-Reductionist Physics: The increasingly apparent possibility that the sought-after final theory is unattainable, combined with the large amount of resources needed for the pursuit of such a theory, led to a different from of opposition to the final theory program, recruiting itself mainly from other subfields of physics that are closer to experiment and application, most notably condensed matter physics. It calls into question the whole notion of fundamental physics, replacing it with an anti-reductionist set of essentially independent descriptions of the physical world at different scales. The group investigates the emergence and rise of this position in the 1970s, studying the complex interplay between science policy and conceptual arguments. It further investigates the mutual transfer of concepts and methods between condensed matter physics and the final theory program, in the face of ideological opposition and the increasingly combative struggle for funding.