From Einstein's point of view, his General Relativity Theory had strengths as well as failings. For him, its shortcoming mainly was that it did not unify gravitation and electromagnetism and did not provide solutions to field equations which can be interpreted as particle models with discrete mass and charge spectra, As a consequence, General Relativity did not solve the quantum problem, either. Einstein tried to get rid of the shortcomings without losing the achievements of General Relativity Theory. Stimulated by papers (...) of Weyl 465) and Eddington 194), from 1923 onward, he believed that, to reach this goal, one has to transit to space–times which possess more comprehensive geometrical structures than the Riemann space–time. This was the beginning of a decade's lasting search for a unitary field theory. We describe this exciting part of the history of physics, discuss achievements and failures of this development, and ask how these early attempts of a unified theory strike us today. Taking into account the fact that the Equivalence Principle only speaks for a geometrization of gravitation, we consider an alternative way to give those non-Riemannian structures which were introduced by the unitary field approach a physical meaning, namely the meaning of a generalized gravitational field. This is interesting since there are arguments in favor of such a generalization of General Relativity Theory, e.g., the problems the latter theory meets with if one tries to quantize it and to unify gravitation with other interactions. (shrink)

Reminiscing on the fact that E. Schrödinger was rooted in the same physical tradition as M. Planck and A. Einstein, some aspects of his attitude to quantum mechanics are discussed. In particular, it is demonstrated that the quantum-mechanical paradoxes assumed by Einstein and Schrödinger should not exist, but that otherwise the epistemological problem of physical reality raised in this context by Einstein and Schrödinger is fundamental for our understanding of quantum theory. The nonexistence of such paradoxes just shows that quantum-mechanical (...) effects are due to interference and not to interaction. This line of argument leads consequently to quantum field theories with second quantization, and accordingly quantum theory based both on Planck's constant h and on Democritus's atomism. (shrink)

Die Physik unserer Zeit ist ohne die Arbeiten Albert Einsteins undenkbar. Zu seinen wichtigsten wissenschaftlichen Leistungen gehören die Begründung der Speziellen und Allgemeinen Relativitätstheorie, die Mitbegründung der Quantenund Atomphysik und die Ausgestaltung all dieser Theorien. Seine eigentliche Ambition ging aber über das von ihm Erreichte hinaus. Er beabsichtigte, eine einheitliche physikalische Theorie begründen. Diese wollte er nicht durch eine Verbindung der Gesetze der klassischen Felder mit den Regeln der Quantenphysik, sondern durch die Verallgemeinerung seiner Allgemeinen Relativitätstheorie gewinnen. Denn letztere hatte (...) eine gegenüber der vorgängigen Physik epochale Änderung der Beziehung von Geometrie und Physik bewirkt. Gemäß Einsteins Programm einer einheitlichen Theorie sollten alle physikalischen Felder und Teilchen als Konfigurationen eines einheitlichen geometrischen Feldes, das die Struktur der Raum-Zeit-Welt bestimmt, ableitbar sein. Grenzen und Perspektiven dieses Programms werden diskutiert. (shrink)

From both physical and epistemological viewpoints, the following theses, which nowadays are often discussed in the literature, are examined: Nonlinear thermodynamics renders it possible to grasp evolutionary physical processes; for thermodynamics it introduces, instead of idealized reversible time, a directed time into physics; thus a science is established that is nearer to reality than classical physics. To analyze these theses, the relation of thermodynamics to dynamical physics is considered. In particular, it is demonstrated that, in classical as well as in (...) modern thermodynamics, irreversibility is introduced via conditions which must be formulated in addition to the dynamical laws. To show the reason for this, the epistemological status of the physical time conception is analyzed, and its character as a physical measurement quantity is established. (shrink)

The ArgumentThe idea of evolution doubtlessly marks a revolution in our way of thinking. It is the most recent achievement of philosophy and forms the basis of the modern world picture. Current discussions concerning the status of science now convey the impression that any scientific discipline that wants to satisfy modern requirements must also become a theory of evolution. These discussions ignore the reasons which once induced Kant to desist from reformulating classical mechanics as a theory of evolution and instead (...) to found his critical philosophy, according to which the epistemological starting points of natural science and philosophy are different in principle. In other words, there is no examination of whether the reasons given by Kant are of a principle nature so that they are still valid today, but rather, ignoring Kant's arguments, it is taken for granted that a different physical theory than classical mechanics could achieve this.Because nonlinear thermodynamics in particular is often presented as a candidate that justifies hopes of an evolutionary physics, the position of this branch within the structure of physics will be investigated here. It will be seen that a historical component is introduced into physics via initial, boundary, and other supplementary conditions, but that this does not mean that historicity has been grasped in laws, which is of course the point of a scientific theory of development.It is demonstrated that the conclusion drawn for physics by some authors from nonlinear thermodynamics, according to which physics today becomes an evolutionary physics incorporating the cognitive subject, is wrong. The progress made by modern thermodynamics is, without doubt, significant. The widespread philosophical interpretation of thermodynamics rests, however, on an antiquated ontologization of physical concepts and thus on the usual procedure of mechanicism.If one tries to introduce the conception of evolution into natural science by leveling the difference between philosophy and natural science in a mechanistic manner, then the dialectical evolutionary conception which represents a new epoch of human thinking degenerates to an evolutionism, where lawfulness is replaced by accidentalness. (shrink)

It is demonstrated that in quantized general relativity one is led to Jordan-Fock type uncertainty relations implying the occurrence of cut-off lengths. We argue that these lengths (i) represent limitations on the measurability of quantum effects of general relativity and (ii) provide a cut-off length of quantum divergences.

The difference between the measurement bases of classical and quantum mechanics is often interpreted as a loss of reality arising in quantum mechanics. In this paper it is shown that this apparent loss occurs only if one believes that refined everyday experience determines the Euclidean space as the real space, instead of considering this space, both in classical and quantum mechanics, as a theoretical construction needed for measurement and representing one part of a dualistic space conception. From this point of (...) view, Einstein's program of a unified field theory can be interpreted as the attempt to find a physical theory that is less dualistic. However, if one rgards this dualism as resulting from the requirements of measurements, one can hope for a weakening of the dualism but not expect to remove it completely. (shrink)

Rediscussing early arguments have led to the founding of quantum electrodynamics, but it is shown that one cannot employ them for the founding of quantum GRT. These arguments rather demonstrate that Einstein's GRT is essentially classical.

Was ist wirklich? Was ist die Wirklichkeit? Anhand einer epistemologischen Analyse der Physik werden Fragen diskutiert, die der Uberzeugung entspringen, dass das Wissen der exakten Naturwissenschaften -formal-, dass es sogenanntes Verstandeswissen ist, das als solches die Wirklichkeit nicht direkt, nicht adaquat zu reflektieren vermag, dennoch aber die exakten Naturwissenschaften zu allgemeingultigen Gesetzesaussagen uber die Wirklichkeit gelangen. Die Antwort auf die Frage, wie dies moglich ist, wird in der vorliegenden Arbeit gesucht, indem Probleme der Physik sowohl in ihrer modernen Auspragung als (...) auch in ihren antiken Urformen und ihrer klassischen Newtonschen Gestaltung untersucht werden. Dabei ergibt sich, dass die physikalischen Begriffsbildungen massgeblich durch das Prinzip der experimentellen Methode bestimmt sind, das die Begrundung physikalischer Gesetze erst ermoglicht, zugleich aber eine Begrenztheit des physikalischen Wirklichkeitsbegriffs impliziert.". (shrink)