Tachyons, a mysterious variety of hypothetical particles capable of exceeding the speed of light, may play a more important role in our understanding of the universe and its causal structure than scientists previously thought.
Not only have tachyons been shown to be potentially compatible with Einstein’s theory of special relativity, but now, according to an international collaboration of physicists from the University of Warsaw and the University of Oxford, these curious particles could also help shed light on remaining questions about our understanding of the quantum world.
Exceeding the universal speed limit
Tachyons, whose name derives from the Greek word tachyswhich means fast or lively, are supposed to exist in conditions where their minimum speed would be the speed of light. This actually means that they should only be able to move at speeds greater than this universally recognized speed limit.
In comparison, ordinary particles move at a speed less than the speed of light, that is, less than it. As Einstein’s theory of relativity would have it, the universal laws of physics prevent anything from being able to accelerate to the speed of light from a lower speed. But this is not necessarily the case for tachyons, since they are assumed to be born at speeds that already exceed the speed of light. Therefore, the opposite seems to be the case for these unusual particles, which should hypothetically be unable to slow down to the speed of light or lower.
The idea of such superluminal particles originated in theoretical studies conducted in the 1960s by physicist Gerald Feinberg. Although no experimental evidence has ever confirmed their existence, a theoretical framework for how these proposed particles might arise has been developed over the decades, sometimes leading to some rather strange paradoxes.
Among these, a curiosity arises from their superluminal travel speeds, which indicate that tachyons might indeed be able to send information into the past, giving rise to bizarre conditions in which cause and effect could theoretically reverse.
However, new research reveals that despite the implications of their existence, these strange hypothetical particles could be compatible with the theory of special relativity and could also help offer physicists significant new insights into quantum theory.
These new findings could also potentially upend long-held notions about the improbability of superluminal particles, suggesting that tachyons might even play a crucial role in the formation of matter.
Particles that should not exist
In the past, physicists have argued that tachyons are unlikely because their field is thought to have an unstable ground state, which would theoretically lead to so-called “avalanches” of particles. Another argument against the existence of tachyons is that changes in an observer’s frame of reference would also change the number of particles they see. This is problematic for physicists because it would contradict our accepted ideas that particles should exist independently of an observer.
A final conceptual hurdle for tachyons also concerns how the energy of superluminal particles would be assumed to have negative energy values, which poses further problems for physicists trying to understand, as well as existing theories, their existence.
In a recent study by Jerzy Paczos, Kacper Dębski, Szymon Cedrowski, Szymon Charzyński, Krzysztof Turzyński, Andrzej Dragan of the University of Warsaw and Artur Ekert of the University of Oxford, the physics team recognized that all of these apparent challenges to the existence of tachyons may stem from a common fundamental problem.
Basically, the team concluded, based on their research, that the boundary conditions determining physical processes must necessarily include the initial state, but also the final state of the system. By integrating this understanding into their theoretical framework, the team made a surprising discovery: each of the previously recognized constraints on the existence of tachyons could be resolved, allowing these hypothetical particles to become mathematically consistent despite their obvious strangeness.
State Space Extension for Tachyons
At the heart of the team’s work is an approach suggesting that in order to calculate the probability of a quantum process involving tachyons, one must integrate both the past initial state as well as its future final state.
By integrating this understanding into the theory, the researchers found that all the previously cited difficulties disappeared, making current theories of tachyons mathematically consistent. This approach suggests that to calculate the probability of a quantum process involving tachyons, one must consider both its past initial state and its future final state.
Andrzej Dragan, a specialist in quantum and relativistic physics and their oddities, as detailed in his book Unusual Special Relativitynotes that some of the apparent paradoxes that arise from the bizarre nature of tachyons are already basic elements of physics, even if they sometimes seem more like science fiction.
“The idea that the future can influence the present instead of the present determining the future is not new in physics,” Dragan explains. “However, until now, this kind of view was at best an unorthodox interpretation of certain quantum phenomena, and this time we were forced to come to this conclusion by the theory itself.”
According to Dragan, to make room for tachyons in existing theory, he and his colleagues first had to “expand the state space.”
The result, as described in the team’s study, marks the first time that the theory itself has required such insight, resulting in an expanded “state space” that is mathematically capable of accommodating tachyons.
Quantum Entanglement and Beyond
In addition to mathematically resolving the potential existence of tachyons, Dragan and his team’s research has also led to additional possibilities, such as a potentially new variety of quantum entanglement that could blend the past and the future, phenomena that are not currently accounted for in conventional particle theory.
These ideas share similarities with other recent discoveries involving how quantum entanglement could be used to effectively influence the past states of particles, potentially enabling the creation of quantum sensors capable of what some physicists liken to time travel.
The discovery of a new type of quantum entanglement, suggested by Dragan and his colleagues’ research, is particularly intriguing. It would mean that tachyons could be more than just mathematical constructs and could also be observed.
Ultimately, tachyons could be recognized as essential components of the spontaneous symmetry breaking process responsible for the formation of matter, thus playing an important role in the fundamental structure of the universe.
The team’s new paper, “Covariant Quantum Field Theory of Tachyons,” was published in the journal Physical examination D July 9, 2024.
Micah Hanks is the editor and co-founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work on micahhanks.com and on X: @MicahHanks.