Do tachyons exist
Executive summary
Tachyons are hypothetical faster‑than‑light particles that remain unobserved: no experiment has produced verifiable evidence for them, and mainstream physics treats them as highly problematic because of causality and stability concerns [1] [2] [3]. Recent theoretical work shows ways to reframe the mathematics so tachyonic excitations can be consistent within certain quantum frameworks, but those papers explicitly stop short of providing experimental evidence or demonstrating that real, detectable tachyon particles exist [4] [5].
1. What physicists mean by “tachyon” — a definition with consequences
The word tachyon denotes a class of hypothetical particles that would always move faster than light and are often modeled as fields with “imaginary mass,” a technical term from the mathematics of quantum fields rather than a literal whimsy; this definition was popularized in the 1960s by Gerald Feinberg [6] [1]. If such objects existed as ordinary particles they would have unusual kinematics: their energy decreases as their speed increases, and special relativity implies they could not be slowed to light speed, producing paradoxical consequences for cause and effect [1] [2].
2. Theoretical objections: causality, instability, and the vacuum
Classic objections are stark and widely cited: faster‑than‑light particles can be used to send signals backward in time, violating causality and producing paradoxes like the grandfather paradox, and tachyonic fields can indicate instabilities in the theory’s ground state that look like runaway “avalanches” rather than stable particles [1] [2] [4]. Quantum‑field level arguments also flagged observer‑dependent particle counts and vacuum‑decay problems that made many physicists conclude tachyons are inconsistent with known, successful theories [4] [5].
3. Experiments and observational status: absence, not proof of impossibility
Decades of experimental work have found no verified tachyon signals: Cerenkov‑in‑vacuum searches and high‑energy experiments have not detected the telltale signatures one would expect if real faster‑than‑light charged particles existed, and big accelerators such as those at CERN have produced no convincing evidence [7] [3]. Journalism and outreach pieces emphasize that absence of evidence is not a mathematical proof of impossibility — a claim of detection would demand extraordinary evidence because it would overturn deeply tested parts of relativity and causality [8] [2].
4. New theoretical work: mathematical room for tachyons, but with caveats
Recent peer‑reviewed proposals expand the quantum state space and adjust boundary conditions to avoid earlier contradictions, producing formulations where tachyonic modes do not necessarily destroy causality and where novel entanglement mixes past and future in the formalism; authors themselves ask whether such constructions are mere mathematical possibilities or physically realizable particles [4] [5]. These advances matter because they move tachyons from “immediately impossible” to “theoretically subtle,” yet they stop short of predicting specific, testable experimental signatures that would compel the community to accept real tachyon particles [4].
5. Bottom line — do tachyons exist?
The sober scientific answer is: there is no experimental evidence that tachyons exist, and mainstream physics treats them as unlikely because they conflict with well‑tested principles such as causality and vacuum stability; however, theoretical work continues to probe loopholes and consistent mathematical descriptions that keep the question open in principle even as it remains closed in practice [1] [7] [4]. Reporting and popular accounts sometimes conflate speculative mathematical modes, field instabilities, or science‑fiction notions with demonstrable particles; the literature reviewed here shows clear distinctions among mathematical possibility, theoretical viability, and empirical reality [5] [3].