Quantum physicists They compared it to measuring cars in a tunnel: while most cars can exit after a measurable interval, some appear to exit… before they have entered.
Researchers at the University of Toronto say they have observed evidence of “negative time”a phenomenon in which time seems to flow backwards.
The findings, which challenge conventional understandings of light and time, still require peer review, but are already raising intrigue (and skepticism) in the scientific community.
The study addresses how photons (particles of light) interact with matter. Traditionally, when photons pass through atoms, they are absorbed, temporarily energizing the atoms before being re-emitted. This process raises the atoms to a “excited” stateafter which they return to their normal energy levels.
In their experiments, carried out over two years in a meticulously calibrated laboratory, with highly sensitive lasers to avoid distorting the results, the team led by experimental quantum physicist Aephraim Steinberg and the researcher Daniela Angulo sought to measure the time that these atoms remain in their excited state.
Surprisingly, the calculations revealed a duration of less than zero—a concept Steinberg describes as “negative time”.
The researchers compared the phenomenon to measuring cars in a tunnel: While most cars can exit after a measurable interval, some appear to exit before they have entered, a result previously considered inconsequential.
Quantum mechanics, not time travel
The researchers emphasize that this discovery does not imply the possibility of time travel or violations of established physics, but rather interpret “negative time” as a peculiar feature of quantum mechanics.
Quantum particles, like photons, exhibit probabilistic behavior, defying intuitive rules of time and causality.
It is important to note, recalls , that the results align with Einstein’s special theory of relativity, which prohibits faster-than-light travel. The observed photons do not carry any information, ensuring compliance with cosmic speed limits.
“Just an artifact”
The concept of “negative time” has sparked a debate among physicists. Sabine Hossenfelder, a German theoretical physicist, criticized the findings on YouTube, arguing that “negative time” is just a mathematical artifact describing the behavior of photons, not a revelation about the nature of time.
“The negative time in this experiment has nothing to do with the passage of time — it’s just a way of describing how photons travel through a medium and how their phases change,” says the physicist.
Steinberg and Angulo disagree with the German, and say that their results explain why light does not always behave uniformly.
The provocative nature of the findings has also drawn attention to the challenges of communicating complex quantum phenomena. The study author admitted that the term “negative time” can be misinterpretedbut defended its use to stimulate discussion within the scientific community.
Although the discovery has no immediate applications, researchers see it as a springboard for broader exploration of quantum behaviors. And be careful: the authors are not stating that time travel is a possibility.
“We don’t want to say that something has traveled backwards in time,” Steinberg explained: “that’s a misinterpretation.”
For now, we can only hope for Tony de Matos.
