The power of general relativity
Abstract
We study the cosmological and weakfield properties of theories of gravity derived by extending general relativity by means of a Lagrangian proportional to R{sup 1+{delta}}. This scalefree extension reduces to general relativity when {delta}{yields}0. In order to constrain generalizations of general relativity of this power class, we analyze the behavior of the perfectfluid Friedmann universes and isolate the physically relevant models of zero curvature. A stable matterdominated period of evolution requires {delta}>0 or {delta}<1/4. The stable attractors of the evolution are found. By considering the synthesis of light elements (helium4, deuterium and lithium7) we obtain the bound 0.017<{delta}<0.0012. We evaluate the effect on the power spectrum of clustering via the shift in the epoch of matterradiation equality. The horizon size at matterradiation equality will be shifted by {approx}1% for a value of {delta}{approx}0.0005. We study the stable extensions of the Schwarzschild solution in these theories and calculate the timelike and null geodesics. No significant bounds arise from null geodesic effects but the perihelion precession observations lead to the strong bound {delta}=2.7{+}4.5x10{sup 19} assuming that Mercury follows a timelike geodesic. The combination of these observational constraints leads to the overall bound 0{<=}{delta}<7.2x10{sup 19} on theories of this type.
 Authors:
 DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)
 Publication Date:
 OSTI Identifier:
 20711523
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physical Review. D, Particles Fields; Journal Volume: 72; Journal Issue: 10; Other Information: DOI: 10.1103/PhysRevD.72.103005; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ATTRACTORS; COSMOLOGY; DEUTERIUM; DIFFERENTIAL GEOMETRY; ENERGY SPECTRA; GENERAL RELATIVITY THEORY; GEODESICS; GRAVITATION; HELIUM 4; IDEAL FLOW; LAGRANGIAN FUNCTION; LITHIUM 7; NUCLEOSYNTHESIS; SCHWARZSCHILD METRIC; SPACETIME; UNIVERSE
Citation Formats
Clifton, Timothy, and Barrow, John D. The power of general relativity. United States: N. p., 2005.
Web. doi:10.1103/PhysRevD.72.103005.
Clifton, Timothy, & Barrow, John D. The power of general relativity. United States. doi:10.1103/PhysRevD.72.103005.
Clifton, Timothy, and Barrow, John D. Tue .
"The power of general relativity". United States.
doi:10.1103/PhysRevD.72.103005.
@article{osti_20711523,
title = {The power of general relativity},
author = {Clifton, Timothy and Barrow, John D.},
abstractNote = {We study the cosmological and weakfield properties of theories of gravity derived by extending general relativity by means of a Lagrangian proportional to R{sup 1+{delta}}. This scalefree extension reduces to general relativity when {delta}{yields}0. In order to constrain generalizations of general relativity of this power class, we analyze the behavior of the perfectfluid Friedmann universes and isolate the physically relevant models of zero curvature. A stable matterdominated period of evolution requires {delta}>0 or {delta}<1/4. The stable attractors of the evolution are found. By considering the synthesis of light elements (helium4, deuterium and lithium7) we obtain the bound 0.017<{delta}<0.0012. We evaluate the effect on the power spectrum of clustering via the shift in the epoch of matterradiation equality. The horizon size at matterradiation equality will be shifted by {approx}1% for a value of {delta}{approx}0.0005. We study the stable extensions of the Schwarzschild solution in these theories and calculate the timelike and null geodesics. No significant bounds arise from null geodesic effects but the perihelion precession observations lead to the strong bound {delta}=2.7{+}4.5x10{sup 19} assuming that Mercury follows a timelike geodesic. The combination of these observational constraints leads to the overall bound 0{<=}{delta}<7.2x10{sup 19} on theories of this type.},
doi = {10.1103/PhysRevD.72.103005},
journal = {Physical Review. D, Particles Fields},
number = 10,
volume = 72,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}

Recently one of us proposed a general theory of variable rest masses (VMT) compatible with postNewtonian solarsystem experiments for a wide range of its two parameters r and q, provided the asymptotic value of its fundamental field f is in a certain narrow range. Here we show that the stationary matterfree blackhole solutions of the VMT are identical to those of general relativity. In addition for r < 0 and q > 0 (part of the range mentioned), relativistic neutronstar models in the VMT are very similar to their generalrelativistic counterparts. Thus experimental discrimination between the two theories in themore »