A team of researchers from the University of Toronto has announced the discovery of “negative time,” a concept that challenges traditional understandings of time in quantum mechanics.

While the findings have generated significant interest, they have also sparked scepticism among some scientific community members.

In a series of experiments conducted in the university’s basement laboratory, the team, led by Daniela Angulo and Aephraim Steinberg, claims to have confirmed the existence of negative time—a phenomenon previously dismissed as an illusion caused by wave interactions with matter.

The “negative time” concept emerged from the team’s investigation into the interaction between light and atoms. In their experiments, light particles, or photons, passed through atoms, some of which were absorbed and later re-emitted. This interaction temporarily altered the atoms, making them excited before returning to their normal condition.

Initially, the researchers aimed to measure the time these atoms remained excited. The result, however, was baffling. “That time turned out to be negative,” explained Steinberg, a professor specialising in experimental quantum physics.

This discovery—where the duration of the excited state was measured as a value less than zero—defied conventional understanding of time.

To illustrate the concept, Steinberg likened the situation to a scenario where a group of cars enters a tunnel at noon, yet the first cars emerge slightly earlier, at 11:59 am.

Previously, such a result would have been dismissed as insignificant. However, the researchers’ study revealed a similar anomaly, which they argue demonstrates the quantum nature of light and its interaction with matter.

While the term “negative time” may sound like something from science fiction, the researchers assert that it offers valuable insight into the behavior of light and quantum mechanics. “This is tough stuff, even for us to talk about with other physicists,” Steinberg said. “We get misunderstood all the time.”

The team is careful to clarify that their discovery does not suggest the possibility of time travel. Instead, they emphasize that this finding is a reflection of quantum mechanics, where particles behave in probabilistic ways rather than following rigid, deterministic rules.

Despite the extraordinary nature of their discovery, the researchers stress that the principle of relativity remains intact.

They explain that the photons in question did not violate Einstein’s theory of special relativity, which posits that nothing can travel faster than light. “We don’t want to say anything traveled backward in time,” Steinberg remarked. “That’s a misinterpretation.”

However, the work has faced criticism from some scientists, including German theoretical physicist Sabine Hossenfelder, who dismissed the findings in a widely viewed YouTube video.

“The negative time in this experiment has nothing to do with time,” Hossenfelder stated. “It’s just a way to describe how photons travel through a medium and how their phases shift.”

Nevertheless, Angulo and Steinberg maintain that their research is crucial for understanding the intricacies of light travel and quantum phenomena. Steinberg acknowledged the controversy over their headline but emphasised that no serious scientist has disputed their experimental results.

“We’ve made our choice about what we think is a fruitful way to describe the results,” he said. “While practical applications are not yet clear, this discovery could open new pathways for exploring quantum behavior.”