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Search Results: 1 - 10 of 2121 matches for " Gravitational Constant "
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The Missing Measurements of the Gravitational Constant
Michelini M.
Progress in Physics , 2009,
Abstract: $G$ measurements are made with torsion balance in "vacuum" to the aim of eliminating the air convection disturbances. Nevertheless, the accuracy of the measured values appears unsatisfying. In 2000 J.Luo and Z.K.Hu first denounced the presence of some unknown systematic error in high vacuum $G$ measurements. In this work a new systematic effect is analyzed which arises in calm air from the non-zero balance of the overall momentum discharged by the air molecules on the test mass. This effect is negligible at vacuum pressures higher than a millibar. However in the interval between the millibar and the nanobar the disturbing force is not negligible and becomes comparable to the gravitational force when the chamber pressure drops to about $10^{-5}$ bar. At the epoch of Heyl's benchmark measurement at 1-2 millibar (1927), the technology of high vacuum pumps was developed, but this chance was not utilized without declaring the reason. The recent $G$ measurements use high vacuum techniques up to $10^{-10}$ and $10^{-11}$ bar, but the effect of the air meatus is not always negligible. We wonder whether the measurements in the interval between the millibar and the nanobar have been made. As a matter of fact, we were not able to find the related papers in the literature. A physical explanation of the denounced unknown systematic error appears useful also in this respect.
Diurnal Variations and Spikes by the Torsind Registered and Their Impact on the Accuracy of G Measurement  [PDF]
A. F. Pugach
International Journal of Astronomy and Astrophysics (IJAA) , 2015, DOI: 10.4236/ijaa.2015.51005
Abstract: The article reports on the results of an analysis of the torsind behavior long-term observations. The torsind is a species of ultralight disc torsion balance. The data analysis showed that the signal recorded contains the 24-hour periodic component presumably associated with the Sun. Moreover, unpredictable strong impacts, forcing torsind disk to rotate in one or another direction, were revealed. Presumably the reason of these effects is the Sun. This indicates the existence of an unknown radiation that bears a torque which may impact on the mechanical systems dynamics. This fact leads to the need to measure the gravitational constant G overnight and during periods of minimum of the solar activity, provided that the G measurements are carried out using a torsion balance.
A Short Discussion on the Gravitational Redshift in the Light of an Alleged Local Variability of the Planck Constant  [PDF]
Carmine Cataldo
Journal of Applied Mathematics and Physics (JAMP) , 2017, DOI: 10.4236/jamp.2017.55087
Abstract: The aim of this paper fundamentally lies in proposing an alternative explanation to the so-called gravitational redshift. The above-mentioned phenomenon, experimentally verified more than half a century ago, is commonly legitimised by means of Special Relativity. In our case, since time is considered as being absolute, we simply postulate a local variability of the Plank constant. Ultimately, we carry out an alternative deduction of the relation that expresses the gravitational redshift as a function of a parameter that, in our case, does not coincide with a Schwarzschild coordinate.
The Sun and Big G Measurements  [PDF]
Jose L. Parra
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.611202
Abstract: On August 29th, 2018, a scientific team reported a measure of the Universal Gravitational Constant G with the highest precision ever. The team completed three experimental campaigns in the same city over the course of a year. That work provided a complete data set useful analyzing the values of Big G change with the distance to the Sun, as is claimed by the author of this paper.
Is Quintessence an Indication of a Time-Varying Gravitational Constant?  [PDF]
Christopher Pilot
Journal of High Energy Physics, Gravitation and Cosmology (JHEPGC) , 2019, DOI: 10.4236/jhepgc.2019.51003
Abstract: A model is presented where the quintessence parameter, w, is related to a time-varying gravitational constant. Assuming a present value of w = -0.98 , we predict a current variation of ？/G = -0.06H0, a value within current observational bounds. H0 is Hubble’s parameter, G is Newton’s constant and ？ is the derivative of G with respect to time. Thus, G has a cosmic origin, is decreasing with respect to cosmological time, and is proportional to H0, as originally proposed by the Dirac-Jordan hypothesis, albeit at a much slower rate. Within our model, we can explain the cosmological constant fine-tuning problem, the discrepancy between the present very weak value of the cosmological constant, and the much greater vacuum energy found in earlier epochs (we assume a connection exists). To formalize and solidify our model, we give two distinct parametrizations of G with respect to “a”, the cosmic scale parameter. We treat G-1 as an order parameter, which vanishes at high energies; at low temperatures, it reaches a saturation value, a value we are close to today. Our first parametrization for G-1 is motivated by a charging capacitor; the second treats G-1(a) by analogy to a magnetic response, i.e., as a Langevin function. Both parametrizations, even though very distinct, give a remarkably similar tracking behavior for w(a) , but not of the conventional form, w(a) = w0 + wa(1-a) , which can be thought of as only holding over a limited range in “a”. Interestingly, both parametrizations indicate the onset of G formation at a temperature of approximately 7×1021 degrees Kelvin, in contrast to the ΛCDM model where G is taken as a constant all the way back to the Planck temperature, 1.42×1032 degrees Kelvin. At the temperature of formation, we find that G has increased to roughly 4×1020 times its current value. For most of cosmic evolution, however, our variable G model gives results similar to the predictions of the ΛCDM model, except in the very early universe, as we shall demonstrate. In fact, in the limit where w approaches -1, the expression, ？/G , vanishes, and we are left with the concordance model. Within our framework, the emergence of dark energy over matter at a scale of a ≈ 0.5 is that point where
Bulk Viscous Anisotropic Cosmological Models with Dynamical Cosmological Parameters G and ∧  [PDF]
S. Kotambkar, G. P. Singh, R. Kelkar
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.74021
Abstract: This paper deals with the Bianchi type I anisotropic models of the universe, filled with a bulk viscous cosmic fluid, in the presence of variable gravitational and cosmological constants. Some exact solutions of Einstein’s gravitational field equations with bulk viscosity, gravitational and cosmological constants have been obtained. Several well known forms of cosmological terms have been considered to discuss the effect of cosmological variables. The new cosmological models presented in this paper approaches to isotropic model with evolution of universe. The physical and dynamical properties of the models have also been discussed.
Precise Ideal Value of the Universal Gravitational Constant G  [PDF]
Abed Elkarim S. Abou Layla
Journal of High Energy Physics, Gravitation and Cosmology (JHEPGC) , 2017, DOI: 10.4236/jhepgc.2017.32020
Abstract: In this paper, we are going to rely on the first law in physics through which we can obtain a precise ideal value of the universal gravitational constant, a thing which has not happened so far. The significance of this law lies in the fact that, besides determining a precise ideal value of the gravitational constant, it connects three different physical disciplines together, which are mechanics, electromagnetism and thermodynamics. It is what distinguishes this from other law. Through this law, we have created the theoretical value of the gravitational constant Gi and we found it equivalent to 6.674010551359 × 10-11 m3·kg-1·s-2. In the discussion, the table of measurements of the gravitational constant was divided into three groups, and the average value of the first group G1 which is the best precision, equals the following sum 6.67401×10-11 m3·kg-1·s-2, and it’s the same equal value to the ideal value Gi that results from the law, as shown through our research that any other experimental values must not exceed the relative standard uncertainty which has a certain amount that is equivalent to a value of 5.325×10-5 and that’s a square value of the fine-structure constant.
Is There a Geomagnetic Component Involved with the Determination of G?  [PDF]
Michael A. Persinger, Linda S. St-Pierre
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.54042
Abstract:

We compared the small quantitative changes (range) in G over repeated measures (days) with recently improved methods of determinations and those recorded over 20 years ago. The range in the Newtonian constant of gravitation G is usually in the order of 400 ppm as reflected in experimentally-determined values. The moderate strength negative correlation between daily fluctuations in G, in the range of 3 × 10-3 of the average value, and an index of global geomagnetic activity reported by Vladimirsky and Bruns in 1998 was also found for the daily fluctuations in the angular deflection θ (in arcseconds) and geomagnetic activity within 24 hr for the Quinn et al. 2013 data. A temporal coupling between increases of geomagnetic activity in the order of 10-9 T with decreases in G in the order of 10-14 m3·kg-1·s-2 could suggest a recondite shared source of variance. The energy equivalence for this change in G and geomagnetic activity within 1 L of water is ~3 × 10-14 J.

Gravitation, Dark Matter and Dark Energy: The Real Universe  [PDF]
Jacob Schaf
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.82016
Abstract: The present work investigates the practical consequences of the recent experimental observations, achieved with the help of the tightly synchronized atomic clocks in orbit, on the current view about the nature of the gravitational fields. While clocks, stationary within gravitational fields, show exactly the gravitational slowing predicted by General Relativity (GR), the GPS clocks, in orbit round earth and moving with earth round the sun, do not show the gravitational slowing of the solar field, predicted by GR. This absence can only mean that the orbital motion of earth cancels this gravitational slowing, which obviously cancels too the spacetime curvature. On the other hand, the Higgs theory introduces the Higgs Quantum Space (HQS) giving mass to the elementary particles by the Higgs mechanism. The HQS thus necessarily governs the inertial motion of matter-energy and is locally their ultimate reference for rest and for motions. Motion with respect to the local HQS and not relative motion is what causes clock slowing, light anisotropy and all the, so-called relativistic effects. Non-uniform motion of the HQS itself necessarily creates inertial dynamics, which, after Einstein’s equivalence of gravitational and inertial effects, is gravitational dynamics. The absence of the gravitational slowing of the GPS clocks by the solar field, together with the null results of the light anisotropy experiments on earth, demonstrates that earth is stationary with respect to the local HQS. This can make sense only if the HQS is moving round the sun according to a Keplerian velocity field, consistent with the planetary motions. This Keplerian velocity field of the HQS is the quintessence of the gravitational fields and is shown to naturally and accurately create the gravitational dynamics, observed on earth, in the solar system, in the galaxy and throughout the universe, as well as all the observed effects of the gravitational fields on light and on clocks.
Bulk Viscous Anisotropic Cosmological Models with Generalized Chaplygin Gas with Time Varying Gravitational and Cosmological Constants  [PDF]
Shubha Kotambkar, Gyan Prakash Singh, Rupali Kelkar
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.76035
Abstract: This paper is devoted to studying the generalized Chaplygin gas models in Bianchi type III space- time geometry with time varying bulk viscosity, cosmological and gravitational constants. We are considering the condition on metric potential \"\". Also to obtain deterministic models we have considered physically reasonable relations like \"\" , and the equation of state for generalized Chaplygin gas given by\"\" . A new set of exact solutions of Einstein’s field equations has been obtained in Eckart theory, truncated theory and full causal theory. Physical behaviour of the models has been discussed.
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