In this note, we point attention to and briefly discuss a curious manuscript of Einstein, composed in 1938 and entitled “Unified Field Theory,” the only such writing, published or unpublished, carrying this title without any further specification. Apparently never intended for publication, the manuscript sheds light both on Einstein′s modus operandi as well as on the public role of Einstein′s later work on a unified field theory of gravitation and electromagnetism.

Seeking to derive the manifestly qualitative world of objects and entities without recourse to fundamental categoricity or qualitativity, I offer an account of how higher-order categorical properties and objects may emerge from a pure-power base. I explore the possibility of ‘fields’ whose fluctuations are force-carrying entities, differentiated with respect to a micro-topology of curled-up spatial dimensions. Since the spacetime paths of gauge bosons have zero ‘spacetime interval’ and no time-like extension, I argue that according them the status of fundamental entities (...) would support a pure-power ontology. Such entities, circulating within self-sustaining micro-topological ‘networks’, feasibly maintain definite spatial configurations of conserved physical quantities, including energy-momentum. Perceived as time-like and massy, and representing fermionic entities, they give rise to the manifest world. (shrink)

Albert Einstein’s practice in physics and his philosophical positions gradually reoriented themselves from more empiricist towards rationalist viewpoints. This change accompanied his turn towards unified field theory and different presentations of himself, eventually leading to his highly programmatic Autobiographical Notes in 1949. Einstein enlisted his own history and professional stature to mold an ideal of a theoretical physicist who represented particular epistemic virtues and moral qualities. These in turn reflected the theoretical ideas of his strongly mathematical unification program and professed (...) Spinozist beliefs. (shrink)

I examine the relation between explanation and unification in both the original Kaluza–Klein theory, which originated in the works of Theodor Kaluza and Oskar Klein in the 1920s, and in the modern Kaluza–Klein theories which date back to the late 1970s and which are still considered by the majority of the physics community to be the best hope for a complete unified theory of all fundamental interactions. I use the conclusions of this case study to assess the merits of Philip (...) Kitcher's account of explanation as unification. I also draw lessons about physicists’ pursuit of the higher dimensional unification of the fundamental forces of nature. (shrink)

We discuss Einstein’s knowledge of projective geometry. We show that two pages of Einstein’s Scratch Notebook from around 1912 with geometrical sketches can directly be associated with similar sketches in manuscript pages dating from his Princeton years. By this correspondence, we show that the sketches are all related to a common theme, the discussion of involution in a projective geometry setting with particular emphasis on the infinite point. We offer a conjecture as to the probable purpose of these geometric considerations.