Toronto: University of Toronto scientists say they have found evidence that “negative time” is not just a theoretical concept but a measurable physical phenomenon.
For decades, researchers have noted instances where light escapes before entering a material, an effect often attributed to wave distortion.
However, recent experiments suggest that this is more than an illusion and may reshape our understanding of time as a concrete, physical entity. exists in sense.
The findings, yet to be published in a peer-reviewed journal, have attracted both global attention and skepticism.
The researchers emphasize that these troubling results highlight a quirk of quantum mechanics rather than a fundamental change in our understanding of time.
“It’s a difficult thing, even for us to talk about with other physicists. We get misunderstood all the time,” said Ephraim Steinberg, a University of Toronto professor who specializes in experimental quantum physics.
While the term “negative time” may sound like a concept lifted from science fiction, Steinberg defends its use, hoping it will spark deeper conversations about the mysteries of quantum physics.
Laser experiments
Years ago, the team began exploring interactions between light and matter.
When light particles, or photons, pass through atoms, some are absorbed by the atoms and later re-emitted. This interaction changes the atoms, temporarily putting them in a higher energy or “excited” state before returning to normal.
In research led by Daniela Angulo, the team set out to measure how long these atoms remained in their excited state. “That time turned out to be negative,” Steinberg explained — that is, a period less than zero.
To see this concept, imagine cars entering a tunnel: Before the experiment, the physicists recognized that the average entry time of a thousand cars might be, for example, noon, the first cars a little early. May exit, 11:59 p.m. This result was previously dismissed as meaningless.
What Angulo and colleagues demonstrated was akin to measuring carbon monoxide levels in a tunnel when the first few cars emerged and found that the readings had a minus sign in front of them.
The relationship is intact.
Experiments in a basement laboratory full of wires and aluminum-clad equipment took two years to perfect. The lasers used had to be carefully calibrated to avoid distorting the results.
Still, Steinberg and Angulo were quick to clarify: No one is claiming that time travel is possible. “We don’t want to say we’ve traveled backwards in time,” Steinberg said. “That’s a misinterpretation.”
The explanation lies in quantum mechanics, where particles like photons behave in fuzzy, probabilistic ways rather than following strict rules.
Rather than following a fixed timeline for absorption and re-emission, these interactions occur across a spectrum of possible durations — some of which defy everyday intuition.
Critically, the researchers say, this does not violate Einstein’s theory of special relativity, which states that nothing can travel faster than light. These photons did not carry any information beyond any cosmic speed limit.
A divisive discovery
The concept of “negative time” has drawn both attention and skepticism, particularly from prominent voices in the scientific community.
German theoretical physicist Sabine Hosenfelder, for one, criticized the work in a YouTube video viewed by more than 250,000 people, saying, “Negative time in this experiment has nothing to do with the passage of time — it’s just the statement. There’s a way to figure out how photons travel through a medium and how their phases change.”
Angulo and Steinberg stepped back and said their research addresses a critical gap in understanding why light doesn’t always travel at a constant speed.
Steinberg acknowledged the controversy over the provocative title of his paper but pointed out that no serious scientist had challenged the experimental results.
“We’ve made our choices about what we think is a productive way to describe the results,” he said, adding that while practical applications remain elusive, the results of quantum phenomena are important. Opens up new avenues for exploration.
“I’ll be honest, right now I have no choice but to look at the applications we’re looking at,” he admitted. “We’ll keep thinking about it, but I don’t want to get people’s hopes up.”