Tachyon

Tachyon
Classification	Elementary particle
Status	Hypothetical
Theorized	1967

A tachyon (/ˈtækiɒn/) or tachyonic particle is a hypothetical particle that always travels faster than light. Physicists believe that faster-than-light particles cannot exist because they are inconsistent with the known laws of physics.^[1]^[2] If such particles did exist they could be used to send signals faster than light and into the past. According to the theory of relativity this would violate causality, leading to logical paradoxes such as the grandfather paradox.^[1] Tachyons would exhibit the unusual property of increasing in speed as their energy decreases, and would require infinite energy to slow to the speed of light. No verifiable experimental evidence for the existence of such particles has been found.

In the 1967 paper that coined the term, Gerald Feinberg proposed that tachyonic particles could be made from excitations of a quantum field with imaginary mass.^[3] 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.^[4] The term tachyonic field refers to imaginary mass fields rather than to faster-than-light particles.^[2]^[5]

^ ^a ^b Cite error: The named reference Tipler was invoked but never defined (see the help page).
^ ^a ^b Randall, Lisa (2005). Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions. Harper Collins. p. 286. ISBN 9780060531089. People initially thought of tachyons as particles traveling faster than the speed of light ... But we now know that a tachyon indicates an instability in a theory that contains it. Regrettably, for science fiction fans, tachyons are not real physical particles that appear in nature.
^ Cite error: The named reference Feinberg 1967-1969 was invoked but never defined (see the help page).
^ Cite error: The named reference Aharonov-etal-1969 was invoked but never defined (see the help page).
^ Cite error: The named reference Sen was invoked but never defined (see the help page).

[Tipler-1] Cite error: The named reference Tipler was invoked but never defined (see the help page).

[Randall_2005_p286-2] Randall, Lisa (2005). Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions. Harper Collins. p. 286. ISBN 9780060531089. People initially thought of tachyons as particles traveling faster than the speed of light ... But we now know that a tachyon indicates an instability in a theory that contains it. Regrettably, for science fiction fans, tachyons are not real physical particles that appear in nature.

[Feinberg_1967-1969-3] Cite error: The named reference Feinberg 1967-1969 was invoked but never defined (see the help page).

[Aharonov-etal-1969-4] Cite error: The named reference Aharonov-etal-1969 was invoked but never defined (see the help page).

[Sen-5] Cite error: The named reference Sen was invoked but never defined (see the help page).

[1]

[2]

[3]

[4]

[5]