Tachyons are hypothetical particles that always travel faster than light. Until recently, they were generally regarded as entities that did not fit into the special theory of relativity. According to a new paper in the journal Physical Review D, these faster-than-light particles are ‘not only not ruled out by the theory, but allow us to understand its causal structure better.’
An AI impression of tachyons.
“Motion at speeds beyond the speed of light is one of the most controversial issues in physics,” said Professor Andrzej Dragan from the University of Warsaw and National University of Singapore and his colleagues.
“Hypothetical particles that could move at superluminal speeds, called tachyons, are the enfant terrible of modern physics.”
“Until recently, they were widely regarded as creations that do not fit into the special theory of relativity.”
“At least three reasons for the non-existence of tachyons within quantum theory were known so far,” they added.
“The first is the ground state of the tachyon field was supposed to be unstable, which would mean that such superluminal particles would form avalanches.”
“The second is a change in the inertial observer was supposed to lead to a change in the number of particles observed in his reference system, yet the existence of, say, seven particles cannot depend on who is looking at them.”
“The third reason is the energy of the superluminal particles could take on negative values.”
“The difficulties with tachyons so far had a common cause,” the physicists said.
“It turned out that the boundary conditions that determine the course of physical processes include not only the initial state but also the final state of the system.”
“To put it simply: in order to calculate the probability of a quantum process involving tachyons, it is necessary to know not only its past initial state but also its future final state.”
“Once this fact was incorporated into the theory, all the difficulties mentioned earlier completely disappeared and tachyon theory became mathematically consistent.”
“It’s a bit like Internet advertising — one simple trick can solve your problems,” Professor Dragan said.
“The idea that the future can influence the present instead of the present determining the future is not new in physics.”
“However, until now, this type of view has at best been an unorthodox interpretation of certain quantum phenomena, and this time we were forced to this conclusion by the theory itself.”
“To make room for tachyons we had to expand the state space.”
“We also predict that the expansion of the boundary conditions has its consequences: a new kind of quantum entanglement appears in the theory, mixing past and future, which is not present in conventional particle theory.”
The team’s paper also raises the question of whether tachyons described in this way are purely a mathematical possibility or whether such particles are likely to be observed one day.
“Tachyons are not only a possibility but are, in fact, an indispensable component of the spontaneous breaking process responsible for the formation of matter,” the authors said.
“This hypothesis would mean that Higgs field excitations, before the symmetry was spontaneously broken, could travel at superluminal speeds in the vacuum.”
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Jerzy Paczos et al. 2024. Covariant quantum field theory of tachyons. Phys. Rev. D 110 (1): 015006; doi: 10.1103/PhysRevD.110.015006
This article is a version of a press-release provided by the University of Warsaw.
Source : Breaking Science News