[en] As a consequence of Mach's principle, rotating matter should cause local inertial frames or gyroscopes in its vicinity to undergo a small rotation which is not present in the Newtonian picture. H. Thirring and J. Lense were the first to derive similar predictions from the field equations of general relativity. Since these early days of relativity, a lot of exact and approximate solutions to Einstein's equations have been examined under this point of view. The qualitative features of Machian effects are most easily demonstrated in the cylinder symmetric case, where some exact results are available. For example, space-time is flat inside a uniformly rotating matter shell, and the rotation of this interior with respect to 'infinity' (the distant stars) has a clear meaning. In the more realistic case of what happens near a massive rotating star, one is forced to perform certain approximations. In modern language, Machian effects are described in terms of the twist of timelike killing vector fields. In the linearized theory, the equations that determine the Machian structure generated by a given matter distribution, resemble to some extent those of classical electrodynamics. This correspondence provides a pedagogical approach how to compute the quantitative extent of inertial frame 'dragging'. 6 refs., 5 figs. (Author)

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[en] Assuming the validity of Mach's principle, it is presented a formalism allowing the calculation of inertial reaction forces having the mass distribuition of the entire Friedmann model as their source. In this scheme, the density parameter characterizing the Friedmann model appears in Newton's second law which in this form can be regarded as statement about cosmology. A possible observational consequence and its relation to variable-g theories are discussed

[en] The calculation of the trajectories in the Sun–Earth–Mars system is performed using two different models, both in the framework of Newtonian mechanics. The first model is the well-known Copernican system, which assumes that the Sun is at rest and that all the planets orbit around it. The second is a less well-known model, developed by Tycho Brahe (1546–1601), according to which the Earth stands still, the Sun orbits around the Earth, and the other planets orbit around the Sun. The term ‘neo-Tychonian system’ refers to the assumption that orbits of distant masses around the Earth are synchronized with the Sun's orbit. It is the aim of this paper to show the kinematical and dynamical equivalence of these systems, under the assumption of Mach's principle. (paper)

[en] The Hughes-Drever experiment has shown inertial mass to be isotropic to approximately 10^-23, which presents difficulties for Machian theories of inertia, according to which nearby bodies such as the sun or the galaxy should produce anisotropies. However, if inertial influence is propagated in the same way as light, the presence of a nearby body causes a change in the apparent position of distant objects which effectively renormalizes the background contribution to inertia, making it anisotropic. To first order al least, this induced effective anisotropy can cancel the anisotropy due to the local body

[en] The ether hypothesis has played an important role in the evolution of physics till the beginning of the present century. It is believed to have been killed on the advent of the theory of special relativity, but the authors quote extensively from a lecture that Einstein gave in 1920 to repudiate this belief. A consequence of the existence of ether in relation to space-like particles is also described. (Auth.)

[en] This paper is a development of an observation made in a previous one [1]. We obtain, under some simplifying assumptions, the evolution of the shape of the Mach's envelope in a non homogeneous medium when the punctual source has an arbitrary motion. As an application, the shape that corresponds to a supersonic motion in a non homogeneous atmosphere is found. (Author) 5 refs

[en] The isotropy of the microwave background has been interpreted as support for Mach's principle in restricting the amount of source-free gravitational shear and rotation in homogeneous cosmological models. We show that recent observations of a 0.1% anisotropy in the background radiation imply similar restrictions on the presence of inhomogeneous source-free shear if it is assumed that the background comes from a representative volume of the Universe

No abstract available