TACHYONS
Exploring Faster-Than-Light Particles in Theoretical Physics
The definitive educational resource on hypothetical superluminal particles, from Gerald Feinberg's 1967 proposal to modern string theory and cosmology.
What Are Tachyons?
Tachyons are hypothetical particles that travel faster than light. First proposed by physicists E.C.G. Sudarshan and O.M.P. Bilaniuk in 1962, and named by Gerald Feinberg in his landmark 1967 paper, these theoretical particles challenge our understanding of physics and causality.
Unlike ordinary matter (bradyons) which can never reach the speed of light, and photons (luxons) which always travel at exactly the speed of light, tachyons would inhabit a third domain where the speed of light is a floor rather than a ceiling. To date, no experimental evidence for their existence has been found, but their study has profoundly influenced quantum field theory, string theory, and cosmology.
Key Properties
- Always travel faster than light
- Have imaginary mass (m = iμ)
- Speed increases as energy decreases
- Never observed experimentally despite extensive searches
Theoretical Framework
- Special relativity extensions for v > c
- Quantum field theory and tachyon condensation
- Causality paradoxes and time reversal
- String theory vacuum instabilities
Explore Tachyon Physics
Deep, authoritative coverage of every aspect of tachyon science, from foundational mathematics to cutting-edge research.
Physics and Mathematics
The Lorentz transformation for superluminal velocities, imaginary mass derivation, spacelike four-momentum, and Feinberg's reinterpretation principle.
Theoretical Framework
Tachyon condensation, spontaneous symmetry breaking, the Higgs mechanism, and vacuum instability in bosonic string theory.
Historical Development
From Sommerfeld's 1904 speculation to Feinberg's 1967 paper and the 2011 OPERA neutrino anomaly at CERN.
Detection Methods
Vacuum Cherenkov radiation, time-of-flight arrays, invariant mass kinematics, and cosmic ray shower analysis.
Current Research
Tachyonic inflation, D-brane annihilation, retrocausality in quantum mechanics, and dark energy models.
Frequently Asked Questions
Answers to common questions about tachyons, imaginary mass, time travel, and faster-than-light physics.
In-Depth Topics
Comprehensive guides on specific topics in tachyon physics and faster-than-light research.
Faster Than Light Particles
Everything we know about superluminal particles, from tachyons to apparent FTL phenomena.
Tachyon vs Photon
Imaginary mass versus zero mass: the absolute boundary of the speed of light.
Bradyon, Luxon, Tachyon
The three-class particle taxonomy based on their relationship to the speed of light.
Imaginary Mass Explained
What imaginary mass really means in physics, and why it signals vacuum instability.
The Tachyonic Antitelephone
Tolman's paradox and how FTL communication creates causal loops.
Tachyon Field Cosmology
How rolling tachyon fields on decaying D-branes model dark energy.
Tachyons in String Theory
Bosonic string instability, Sen's conjectures, and superstring resolution.
The Casimir Effect
Negative vacuum energy, the Scharnhorst effect, and superluminal photons.
The OPERA Experiment
The 2011 faster-than-light neutrino anomaly and what went wrong.
Alcubierre Warp Drive
How warp drive theory connects to tachyonic physics and exotic matter.
All Articles
Browse our complete collection of articles on tachyon physics and related topics.
Academic Resources
Key papers, textbooks, and references for further study.
Understanding Tachyons: A Brief Overview
The concept of particles traveling faster than light has fascinated physicists since Arnold Sommerfeld first considered the possibility in 1904. However, the modern theory of tachyons began with a 1962 paper by E.C.G. Sudarshan, V.K. Deshpande, and O.M.P. Bilaniuk, titled "Meta-Relativity," which showed that special relativity does not actually forbid faster-than-light particles as long as they are never decelerated below the speed of light.
In 1967, Columbia University physicist Gerald Feinberg published his seminal paper "Possibility of Faster-Than-Light Particles" in the Physical Review, coining the term "tachyon" from the Greek word tachys meaning "swift." Feinberg developed a quantum field theory for these particles and introduced the reinterpretation principle, which resolved the problem of negative-energy states by recasting backward-in-time tachyons as forward-in-time anti-tachyons.
Today, the term "tachyon" has evolved beyond Feinberg's original proposal. In modern physics, tachyons in string theory typically refer to unstable vacuum states rather than physical faster-than-light particles. The process of tachyon condensation, where a tachyonic field rolls to its true energy minimum, is now understood to be intimately connected to the Higgs mechanism and models of dark energy in cosmology.
Despite extensive experimental searches using vacuum Cherenkov radiation detectors, time-of-flight measurements, and particle collider kinematics, no physical tachyon has ever been observed. The most famous near-miss was the 2011 OPERA experiment at CERN, which initially reported neutrinos traveling faster than light before the result was traced to equipment errors.