[en] The results are given of detailed UBV photometry of the peculiar galaxy NGC 2685 based on 10 negatives obtained with the 2.6-m telescope of the Biurakan Observatory. Consideration of all the available observational data (photometric, spectroscopic, and polarization) suggests that NGC 2685 is a pair of colliding galaxies. 18 references

[en] We deal with the possibility to establish a relation between the self-interaction effect of ν(x) fields, which, in essence, leads to the appearance and the non-local and partial local neutrino-gravitational interaction, introduced by the author. (author)

[en] The Wheeler-DeWitt equation provides a model of the Universe as a timeless, isolated system. Page and Wootters developed the conditional probability interpretation (CPI) to account for the experience of time within this timeless model by identifying part of the Universe as the clock. In resolving criticisms of the CPI, some investigators have since concluded that the clock must be completely isolated from the remainder of the Universe. This isolation has also been used to reinforce the conclusion that time must be an illusion. However, some interactions must exist between all subsystems of the Universe as gravitational effects, however weak, cannot be shielded. Here, we present the results of an investigation which used a toy model to consider the implications of including interactions. Although counter intuitive, their inclusion is seen to directly correlate with the accuracy of measurements of the clock state. The case is then made that, if interactions are indeed a necessary feature of the CPI, the viability of treating time as an illusion needs to be reconsidered. We conclude that the experience of time can be interpreted as a real phenomenon, which naturally incorporates an arrow of time, once interactions are taken seriously in the CPI paradigm. (paper)

[en] It is argued that the tetrad in a recent paper by Porto and Rothstein on gravitational spin-spin coupling should not have the given form. The fixation of that tetrad was suggested by Steinhoff, Hergt, and Schaefer as a possible source for the disagreement found in the spin-squared dynamics. However, this inconsistency will only show up in the next-to-leading order spin-orbit dynamics and not in the spin-squared dynamics. Instead, the disagreement found at the next-to-leading order spin-squared level is due to a sign typo in the spin-squared paper by Porto and Rothstein.

[en] Using a lagrangian formalism of invariantive mechanics the deviation of the light in a gravitational field is studied; the result is in full agreement with the theory of General Relativity. (author)

[en] Abstract only

[en] The complex mass term of a quark does not violate time reversal or parity in gravitational interactions, in spite of an axial anomaly.

[en] In Ref. Donini and Marimón (Eur Phys J C 76:696, arXiv:1609.05654, 2016), an experimental setup aiming at the measurement of deviations from the Newtonian 1/r${}^2$ distance dependence of gravitational interactions was proposed. The theoretical idea behind this setup was to study the trajectories of a "Satellite" with a mass $m_S$ ∼ $\mathcal{O}$(10${}^{-<!--\; ???\; -->9}$) g around a "Planet" with mass $m_P$$\in <!--\; ???\; -->$ [10${}^{-<!--\; ???\; -->7}$,10${}^{-<!--\; ???\; -->5}$] g, looking for precession of the orbit. The observation of such feature induced by gravitational interactions would be an unambiguous indication of a gravitational potential with terms different from 1/r and, thus, a powerful tool to detect deviations from Newton's 1/r${}^2$ law. In this paper we optimize the proposed setup in order to achieve maximal sensitivity to look for such Beyond-Newtonian corrections. We then study in detail possible background sources that could induce precession and quantify their impact on the achievable sensitivity. We finally conclude that a dynamical measurement of deviations from newtonianity can test Yukawa-like corrections to the 1/r potential with strength as low as as α ∼ 10${}^{-<!--\; ???\; -->2}$ for distances as small as λ ∼ 10 μm.

[en] The techniques described in an earlier paper were used to determine masses of 104 asteroids by the method of asteroid-asteroid gravitational interaction. For each of the 104 perturbers, 4 large sets of test particles selected by different criteria were used to calculate 4 mass values from a weighted mean of individual results within each set. The sheer number of test particles and observations ameliorates the effects of random observational errors and the type of systematic errors known to have affected specific observatories at specific times. It also reduces the effect of mismodeled attractions by perturbers other than the one being estimated, because the various test particles are affected to different degrees and in different directions. For most of the perturbers that have been analyzed by others, the results of this study agree reasonably well with values published in the past decade, giving credence to the approach. Thirty-eight of the results appear to be the first published masses for the respective asteroids, and 12 are the first determinations based on asteroid-asteroid interactions. Unrealistic and/or negative masses were obtained for some perturbers. Causes for this phenomenon are discussed and various means to obtain reasonable numbers are evaluated.

[en] Scattering involving very high energies in gravitational systems is discussed. The different origins of the non-leading contributions to the scattering amplitude are briefly reviewed. 6 refs, 2 figs