Gravitational physics

From Academic Kids

Metric theories of gravitation (e.g., General Relativity) postulate the Equivalence principle (EP): all bodies in vacuum fall identically regardless of composition and internal structure; inertial and gravitational masses are fundamentally indistinguishable. Spacetime curvature immediately follows.

Affine theories of gravitation ignore the EP, instead modeling gravitation as spacetime torsion. The two entirely different approaches give wholly identical predictions, with one class of exceptions: affine theories predict at least three classes of Equivalence Principle violation based upon test mass physical spin[1], test mass polarized electron spin[2], or test mass atomic lattice opposite geometric parity[3]. The first two are theoretically too small to observe. <P> Testing for reproducible Equivalence Principle violation is therefore of major interest. No violation beyond experimental error was ever observed. Test mass opposite parity EP experiments have never been performed. The proper test of spacetime geometry may be test mass geometry. Somebody should look. <P> Historic Equivalence Principle Tests[6] <P>

YearInvestigatorAccuracy*Method
  500? Philoponus[7] "small" Drop Tower
1590? Galileo[4] 2·10-2 Pendulum, Drop Tower
1686 Newton[5]    10-3 Pendulum
1832 Bessel[8] 2·10-5 Pendulum
1910 Southerns[9] 5·10-6 Pendulum
1918 Zeeman[10] 3·10-8 Torsion Balance
1922 Eötvös[11] 5·10-9 Torsion Balance
1923 Potter[12] 3·10-6 Pendulum
1935 Renner[13] 2·10-9 Torsion Balance
1964 Dicke,Roll,Krotkov[14] 3·10-11 Torsion Balance
1972 Braginsky,Panov[15]    10-12 Torsion Balance
1976 Shapiro, et al.[16]    10-12 Lunar Laser Ranging
1981 Keiser,Faller[17] 4·10-11 Fluid Support
1987 Niebauer, et al.[18]    10-10 Drop Tower
1989 Heckel, et al.[19]    10-11 Torsion Balance
1990 Adelberger, et al.[20]    10-12 Torsion Balance
1999 Baeßler, et al.[21] 5·10-13 Torsion Balance
2005? MiniSTEP[22]    10-17 Earth Orbit
  • "Accuracy" is the measurable difference/average of the weight vectors of the contrasted (sets of) test masses.

<P> [1] Phys. Rev. D 66 022002 (2002)
[2] Phys. Rev. D 42 977 (1990)
http://arXiv.org/abs/gr-qc/0102020
[3] http://www.mazepath.com/uncleal/qz.pdf
[4] Galilei, Galileo. Discorsi e Dimostrazioni Matematiche Intorno a Due Nuove Scienze (Appresso gli Elsevirii, Leida: 1638) (Discourses and Mathematical Demonstrations Concerning Two New Sciences, Elsevier Press, Leiden: Netherlands, 1638)
[5] Jahrbuch der Radioaktivität Elect. 4 411 (1907)
[6]Ciufolini & Wheeler Gravitation and Inertia (Princeton University Press: Princeton, 1995) pp. 117-119
http://einstein.stanford.edu/STEP/information/data/gravityhist2.html
[7]Philoponus, J, Corollaries on Place and Void David Furley trans. (Ithaca, NY: Cornell University Press, 1987)
[8]Ann. Physik und Chemie (Poggendorff) 25 401 (1832)
[9]Proc. Roy. Soc. Lond. 84 325 (1910)
[10]Proc. K. Akad. Amsterdam 20(4) 542 (1918)
[11]Math. Naturw. Ber. aus. Ungarn 8 65 (1889)
Ann. Physik (Leipzig) 68 11 (1922)
Phys. Rev. D 61(2) 022001 (1999)
[12]Proc. Roy. Soc. Lond. 104 588 (1923)
[13]és Természettudományi Értesitö 53 569 (1935)
[14]Ann. Phys. (NY) 26 442 (1964)
[15]Zh. Eksp. Teor. Fiz. 61 873 (1971)
Sov. Phys. JETP 34(3) 463 (1972)
[16]Phys. Rev. Lett. 36 555 (1976)
[17]Bull. Am. Phys. Soc. 24 579 (1979)
[18]Phys. Rev. Lett. 59 609 (1987)
[19]Phys. Rev. Lett. 62 609 (1989)
[20]Phys. Rev. D 42 3267 (1990)
[21]Class. Quantum. Grav. 18(13) 2393 (2001)
Phys.Rev. Lett 83(18) 3585 (1999)
[22]http://einstein.stanford.edu/STEP/

sl:gravitacijska fizika

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