Tachyon: Difference between revisions - Wikipedia

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In the 1967 paper that coined the term, [[Gerald Feinberg]] proposed that tachyonic particles could be made from [[Quantum excitation (accelerator physics)|excitations]] of a [[Quantum field theory|quantum field]] with [[imaginary mass]].<ref name="Feinberg 1967-1969" /> However, it was soon realized that Feinberg's model did not in fact allow for [[superluminal]] (faster-than-light) particles or signals and that tachyonic fields merely give rise to instabilities, not causality violations.<ref name="Aharonov-etal-1969" /> The term [[tachyonic field]] refers to imaginary mass fields rather than to faster-than-light particles.<ref name="Randall 2005 p286" /><ref name="Sen" />

The term comes from the {{lang-el|[[Wiktionary:ταχύταχύς|ταχύταχύς]]}}, ''tachy'', meaning ''swift''.<ref name="FoxKuperLipson">{{Cite journal |last=Fox |first=R. |last2=Kuper |first2=C. G. |last3=Lipson |first3=S. G. |date=1970 |title=Faster-Than-Light Group Velocities and Causality Violation |url=https://www.jstor.org/stable/77636 |journal=Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences |volume=316 |issue=1527 |pages=515–524 |issn=0080-4630}}</ref>{{rp|515|q= The name 'tachyon' was proposed by Feinberg (I967), from the Greek ταχύς ('swift').}} The complementary particle types are called [[Massless particle|luxons]] (which always move at the [[speed of light]]) and [[bradyons]] (which always move slower than light); both of these particle types are known to exist.

== History ==