Portal:Radiation astronomy/Resource/35

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Superluminals[edit | edit source]

Main articles: Radiation astronomy/Superluminals and Superluminal astronomy
The two images are a top panel of Hubble Space Telescope image showing the M87 jet streaming out from the galaxy's nucleus (bright round region at far left) and a bottom panel which contains a sequence of Hubble images showing motion of something at six times the speed of light. Credit: John Biretta/NASA/ESA/Space Telecsope Science Institute.

Superluminal refers to the propagation of information or matter faster than the speed of light. Under the special theory of relativity, a particle (that has [mass in special relativity] rest mass) with subluminal velocity needs infinite energy to accelerate to the speed of light, although special relativity does not forbid the existence of particles that travel faster than light at all times (tachyons).

On the other hand, what some physicists refer to as "apparent" or "effective" FTL[1][2][3][4] depends on the hypothesis that unusually distorted regions of spacetime might permit matter to reach distant locations in less time than light could in normal or undistorted spacetime. Although according to current theories matter is still required to travel subluminally with respect to the locally distorted spacetime region, apparent FTL is not excluded by general relativity.

Tachyonic γ rays have not been observed directly as of 2007.[5] "The tachyonic spectral densities generated by ultra-relativistic electrons in uniform motion are fitted to the high-energy spectra of Galactic supernova remnants, such as RX J0852.0−4622 and the pulsar wind nebulae in G0.9+0.1 and MSH 15-52. ... Tachyonic cascade spectra are quite capable of generating the spectral curvature seen ... Estimates on the electron/proton populations generating the tachyon flux are obtained from the spectral fits"[5]

"Tachyonic radiation implies superluminal signal transfer [1-7], the energy quanta propagating faster than light in vacuum, in contrast to rotating superluminal light sources emitting vacuum Cherenkov radiation [8, 9]."[6] "The existence of superluminal energy transfer has not been established so far, and one may ask why. There is the possibility that superluminal quanta just do not exist, the vacuum speed of light being the definitive upper bound. There is another explanation, the interaction of superluminal radiation with matter is very small, the quotient of tachyonic and electric fine-structure constants being q2/e2 ≈ 1.4 x 10-11 [5], and therefore superluminal quanta are hard to detect."[6]

“Observed variations concerning the brightness distributions in four extragalactic radio sources were so rapid that the apparent transverse velocity of expansion is greater than the velocity of light.”[7]

References[edit | edit source]

  1. ↑ Gonzalez-Diaz, P. F. (2000). "Warp drive space-time". Physical Review D 62 (4): 044005. doi:10.1103/PhysRevD.62.044005. http://omnis.if.ufrj.br/~mbr/warp/etc/PRD62_44005.pdf. 
  2. ↑ F. Loup, David Waite, E. Halerewicz Jr. (2001). [ttp://arxiv.org/abs/gr-qc/0107097 Reduced Total Energy Requirements for a Modified Alcubierre Warp Drive Spacetime]. ttp://arxiv.org/abs/gr-qc/0107097. 
  3. ↑ Visser, M.; Bassett, B.; Liberati, S. (2000). "Superluminal censorship". Nuclear Physics B: Proceedings Supplement 88: 267–270. doi:10.1016/S0920-5632(00)00782-9. 
  4. ↑ Visser, M.; Bassett, B.; Liberati, S. (1999). "Perturbative superluminal censorship and the null energy condition". AIP Conference Proceedings 493: 301–305. doi:10.1063/1.1301601. ISBN 1-56396-905-X. 
  5. ↑ 5.0 5.1 Roman Tomaschitz (March 2007). "Superluminal cascade spectra of TeV [gamma-ray sources"]. Annals of Physics 322 (3): 677-700. doi:10.1016/j.aop.2006.11.005. http://wallpaintings.at/geminga/superluminal_cascade_spectra_TeV_gamma-ray_sources.pdf. Retrieved 2011-11-24. 
  6. ↑ 6.0 6.1 R Tomaschitz (October 2010). "Superluminal spectral densities of ultra-relativistic electrons in intense electromagnetic wave fields". Applied Physics B Lasers and Optics 101 (1-2): 143-64. doi:10.1007/s00340-010-4182-8. http://wallpaintings.at/geminga/superluminal_spectral_densities_ultra-relativistic_electrons_electromagnetic_wave_fields.pdf. Retrieved 2012-03-21. 
  7. ↑ M. H. Cohen, K. I. Kellermann, D. B. Shaffer, R. P. Linfield, A. T. Moffet, J. D. Romney, G. A. Seielstad, I. I. K. Pauliny-Toth, E. Preuss, A. Witzel, R. T. Schilizzi & B. J. Geldzahler (August 1977). "Radio sources with superluminal velocities". Nature 268: 405-9. doi:10.1038/268405a0. 
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