Kelajuan gravitasi
Dalam teori gravitasi klasik, perubahan dalam medan gravitasi menyebar. Perubahan dalam distribusi energi dan momentum dari materi menghasilkan perubahan berikutnya, di suatu jarak, dari medan gravitasi yang menghasilkannya. Dalam arti yang lebih benar secara fisika, "kelajuan gravitasi" mengacu pada kelajuan gelombang gravitasi, yang merupakan kelajuan yang sama dengan laju cahaya (c).
Pengenalan[sunting | sunting sumber]
Kelajuan gelombang gravitasi dalam teori relativitas umum sama dengan laju cahaya dalam vakum, c.[1] Dalam teori relativitas khusus, konstanta c tidak secara eksklusif tentang cahaya; c adalah kelajuan tertinggi yang mungkin untuk setiap interaksi di alam. Secara formal, c adalah faktor konversi untuk mengubah satuan waktu menjadi satuan ruang.[2] Hal ini menyebabkan c satu-satunya kelajuan yang tidak bergantung pada gerakan pengamat atau sumber cahaya dan/atau gravitasi. Sehingga, kelajuan "cahaya" juga merupakan kelajuan gelombang gravitasi dan partikel tak bermassa lain. Partikel seperti itu mencakup gluon (pembawa gaya kuat), foton yang membentuk cahaya, dan graviton teoretis yang membentuk medan partikel gravitasi terkait (namun demikian teori graviton membutuhkan teori gravitasi kuantum).
Catatan[sunting | sunting sumber]
Referensi[sunting | sunting sumber]
- ^ Hartle, JB (2003). Gravity: An Introduction to Einstein's General Relativity. Addison-Wesley. hlm. 332. ISBN 981-02-2749-3.
- ^ Taylor, Edwin F. and Wheeler, John Archibald, Spacetime Physics, 2nd edition, 1991, p. 12.
- Kopeikin, Sergei M. (2001). "Testing Relativistic Effect of Propagation of Gravity by Very-Long Baseline Interferometry". Astrophys. J. 556 (1): L1–L6. arXiv:gr-qc/0105060
. Bibcode:2001ApJ...556L...1K. doi:10.1086/322872. - Asada, Hidecki (2002). "The Light-cone Effect on the Shapiro Time Delay". Astrophys. J. 574 (1): L69. arXiv:astro-ph/0206266 . Bibcode:2002ApJ...574L..69A. doi:10.1086/342369.
- Will, Clifford M. (2003). "Propagation Speed of Gravity and the Relativistic Time Delay". Astrophys. J. 590 (2): 683–690. arXiv:astro-ph/0301145 . Bibcode:2003ApJ...590..683W. doi:10.1086/375164.
- Fomalont, E. B. & Kopeikin, Sergei M. (2003). "The Measurement of the Light Deflection from Jupiter: Experimental Results". Astrophys. J. 598 (1): 704–711. arXiv:astro-ph/0302294 . Bibcode:2003ApJ...598..704F. doi:10.1086/378785.
- Kopeikin, Sergei M. (Feb 21, 2003). "The Measurement of the Light Deflection from Jupiter: Theoretical Interpretation". arΧiv:astro-ph/0302462.
- Kopeikin, Sergei M. (2003). "The Post-Newtonian Treatment of the VLBI Experiment on September 8, 2002". Phys. Lett. A. 312 (3–4): 147–157. arXiv:gr-qc/0212121 . Bibcode:2003PhLA..312..147K. doi:10.1016/S0375-9601(03)00613-3.
- Faber, Joshua A. (Mar 14, 2003). "The speed of gravity has not been measured from time delays". arΧiv:astro-ph/0303346.
- Kopeikin, Sergei M. (2004). "The Speed of Gravity in General Relativity and Theoretical Interpretation of the Jovian Deflection Experiment". Classical and Quantum Gravity. 21 (13): 3251–3286. arXiv:gr-qc/0310059 . Bibcode:2004CQGra..21.3251K. doi:10.1088/0264-9381/21/13/010.
- Samuel, Stuart (2003). "On the Speed of Gravity and the v/c Corrections to the Shapiro Time Delay". Phys. Rev. Lett. 90 (23): 231101. arXiv:astro-ph/0304006 . Bibcode:2003PhRvL..90w1101S. doi:10.1103/PhysRevLett.90.231101. PMID 12857246.
- Kopeikin, Sergei & Fomalont, Edward (2006). "On the speed of gravity and relativistic v/c corrections to the Shapiro time delay". Physics Letters A. 355 (3): 163–166. arXiv:gr-qc/0310065 . Bibcode:2006PhLA..355..163K. doi:10.1016/j.physleta.2006.02.028.
- Hideki, Asada (Aug 20, 2003). "Comments on "Measuring the Gravity Speed by VLBI"". arΧiv:astro-ph/0308343.
- Kopeikin, Sergei & Fomalont, Edward (2006). "Aberration and the Fundamental Speed of Gravity in the Jovian Deflection Experiment". Foundations of Physics. 36 (8): 1244–1285. arXiv:astro-ph/0311063 . Bibcode:2006FoPh...36.1244K. doi:10.1007/s10701-006-9059-7.
- Carlip, Steven (2004). "Model-Dependence of Shapiro Time Delay and the "Speed of Gravity/Speed of Light" Controversy". Class. Quant. Grav. 21 (15): 3803–3812. arXiv:gr-qc/0403060 . Bibcode:2004CQGra..21.3803C. doi:10.1088/0264-9381/21/15/011.
- Kopeikin, Sergei M. (2005). "Comment on 'Model-dependence of Shapiro time delay and the "speed of gravity/speed of light" controversy". Class. Quant. Grav. 22 (23): 5181–5186. arXiv:gr-qc/0510048 . Bibcode:2005CQGra..22.5181K. doi:10.1088/0264-9381/22/23/N01.
- Pascual-Sánchez, J.-F. (2004). "Speed of gravity and gravitomagnetism". Int. J. Mod. Phys. D. 13 (10): 2345–2350. arXiv:gr-qc/0405123 . Bibcode:2004IJMPD..13.2345P. doi:10.1142/S0218271804006425.
- Kopeikin, Sergei (2006). "Gravitomagnetism and the speed of gravity". Int. J. Mod. Phys. D. 15 (3): 305–320. arXiv:gr-qc/0507001 . Bibcode:2006IJMPD..15..305K. doi:10.1142/S0218271806007663.
- Samuel, Stuart (2004). "On the Speed of Gravity and the Jupiter/Quasar Measurement". Int. J. Mod. Phys. D. 13 (9): 1753–1770. arXiv:astro-ph/0412401 . Bibcode:2004IJMPD..13.1753S. doi:10.1142/S0218271804005900.
- Kopeikin, Sergei (2006). "Comments on the paper by S. Samuel "On the speed of gravity and the Jupiter/Quasar measurement"". Int. J. Mod. Phys. D. 15 (2): 273–288. arXiv:gr-qc/0501001 . Bibcode:2006IJMPD..15..273K. doi:10.1142/S021827180600853X.
- Kopeikin, Sergei & Fomalont, Edward (2007). "Gravimagnetism, Causality, and Aberration of Gravity in the Gravitational Light-Ray Deflection Experiments". General Relativity and Gravitation. 39 (10): 1583–1624. arXiv:gr-qc/0510077 . Bibcode:2007GReGr..39.1583K. doi:10.1007/s10714-007-0483-6.
- Kopeikin, Sergei & Fomalont, Edward (2008). "Radio interferometric tests of general relativity". "A Giant Step: from Milli- to Micro-arcsecond Astrometry", Proceedings of the International Astronomical Union, IAU Symposium. 248 (S248): 383–386. Bibcode:2008IAUS..248..383F. doi:10.1017/S1743921308019613.
- Zhu, Yin (2011). "Measurement of the Speed of Gravity". MISSING LINK. .
Pranala luar[sunting | sunting sumber]
- Does Gravity Travel at the Speed of Light? in The Physics FAQ (also here).
- Measuring the Speed of Gravity at MathPages
- Hazel Muir, First speed of gravity measurement revealed, a New Scientist article on Kopeikin's original announcement.
- Clifford M. Will, Has the Speed of Gravity Been Measured? Diarsipkan 2006-05-04 di Wayback Machine..
- Kevin Carlson, MU physicist defends Einstein's theory and 'speed of gravity' measurement.