If time is determined by the speed of light, how would you determine which packets were generated first? Would they be going by some other limiting speed agent other than C?
On 5/12/19, H LV <[email protected]> wrote: > If one can build a transmitter and a receiver to transmit and detect wave > packets travelling with sub c group velocity why can't one do the same for > wave packets with group velocity much greater than c and achieve > communication which is much faster than c? > Harry > > On Fri, May 3, 2019, 11:51 PM Axil Axil <[email protected] wrote: > >> >> >> It should be noted that while Einstein's theory of special relativity >> prevents (real) mass, energy, or information from traveling faster than >> the >> speed of light c (Lorentz et al. 1952, Brillouin and Sommerfeld 1960, >> Born >> and Wolf 1999, Landau and Lifschitz 1997), there is nothing preventing >> "apparent" motion faster than c (or, in fact, with negative speeds, >> implying arrival at a destination before leaving the origin). For >> example, >> the phase velocity and group velocity of a wave may exceed the speed of >> light, but in such cases, no energy or information actually travels >> faster >> than c. Experiments showing group velocities greater than c include that >> of >> Wang et al. (2000), who produced a laser pulse in atomic cesium gas with >> a >> group velocity of -310c. In each case, the observed superluminal >> propagation is not at odds with causality, and is instead a consequence >> of >> classical interference between its constituent frequency components in a >> region of anomalous dispersion (Wang et al. 2000). >> >> Keith Fredericks has an opinion that strange radiation is a tachyon. This >> SR quasiparticle might be tachyonic is that it is most likely based on >> the >> polariton. The polariton does generate superluminal light in the form of >> x-waves. >> >> https://www.nature.com/articles/lsa2017119 >> >> Superluminal X-waves in a polariton quantum fluid >> >> This article shows that a polariton can naturally produce superluminal >> light (X-waves) when excited with a pulsed laser. >> >> This unexpected behavior of light may explain how Strange radiation (SR) >> can be considered a tachyon, a superluminal particle. >> >> >
