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Spacetime diagram showing that moving faster than light implies time travel in the context of special relativity. A spaceship departs from Earth from A to C slower than light. At B, Earth emits a tachyon, which travels faster than light but forward in time in Earth's reference frame. It reaches the spaceship at C.
Faster-than-light (superluminal or supercausal) travel and communication are the conjectural propagation of matter or information faster than the speed of light in vacuum (c). The special theory of relativity implies that only particles with zero rest mass (i.e., photons ) may travel at the speed of light, and that nothing may travel faster.
The speed of light is the upper limit for the speeds of objects with positive rest mass, and individual photons cannot travel faster than the speed of light. [39] This is experimentally established in many tests of relativistic energy and momentum .
In physics, a tachyonic field, or simply tachyon, is a quantum field with an imaginary mass. [1] Although tachyonic particles (particles that move faster than light) are a purely hypothetical concept that violate a number of essential physical principles, at least one field with imaginary mass, the Higgs field, is believed to exist.
In reality, the impulse provided to the cylinder by the burst of light in step (b) cannot travel faster than light, so that when the burst of photons reaches the right wall in step (c), the wall has not yet begun to move. [23] Ohanian has credited von Laue (1911) as having provided the first truly definitive derivation of M 0 = E 0 /c 2. [24]
The hypothetical particles tachyons, defined through being faster than light, have inspired many occurrences in fiction. [1] [2] In general, tachyons are a standby mechanism upon which many science fiction authors rely to establish faster-than-light communication, with or without reference to causality issues, [3] [4] as well as a means to achieve faster-than-light travel. [4]
The current scientific consensus is that faster-than-light communication is not possible, and to date it has not been achieved in any experiment. Superluminal communication other than possibly through wormholes is likely impossible [ 1 ] because, in a Lorentz-invariant theory, it could be used to transmit information into the past .
Therefore, the field operators at spacelike separated points still commute (or anticommute), and information and particles still do not propagate faster than light. [164] Tachyon condensation drives a physical system that has reached a local limit – and might naively be expected to produce physical tachyons – to an alternate stable state ...