Scientists Observe ‘Negative Time’ in Quantum Experiments
AFP/APP
Toronto, Canada: Scientists have long known that light can sometimes appear to exit a material before entering it — an effect previously dismissed as an illusion caused by how waves are distorted by matter.
However, researchers at the University of Toronto, through innovative quantum experiments, now claim to have demonstrated that “negative time” exists in a tangible, physical sense, warranting closer scrutiny.
The findings, yet to be published in a peer-reviewed journal, have attracted global attention and skepticism. Researchers emphasize that these results highlight a peculiar quirk of quantum mechanics rather than a radical shift in our understanding of time.
“This is tough stuff, even for us to talk about with other physicists. We get misunderstood all the time,” said Aephraim Steinberg, a University of Toronto professor specializing in experimental quantum physics. While “negative time” might sound like a concept from science fiction, Steinberg hopes its use will spark deeper discussions about quantum physics’ mysteries.
Laser Experiments
Years ago, the team began exploring interactions between light and matter. When photons pass through atoms, some are absorbed and later re-emitted, temporarily putting the atoms 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 stayed in their excited state. “That time turned out to be negative,” Steinberg explained — a duration less than zero.
To visualize, imagine cars entering a tunnel: while the average entry time for a thousand cars might be noon, the first cars could exit slightly earlier, say 11:59 am. This result was previously dismissed as meaningless. Angulo’s team demonstrated that measuring carbon monoxide levels in the tunnel after the first cars emerged revealed readings with a negative sign.
Relativity Intact
The experiments, conducted in a cluttered basement lab bristling with wires and aluminum-wrapped devices, took over two years to optimize. Carefully calibrated lasers were necessary to avoid distorting the results.
Steinberg and Angulo clarify that no one is claiming time travel is possible. “We don’t want to say anything traveled backward 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 adhering to strict rules. These interactions occur across a spectrum of possible durations, defying everyday intuition.
Critically, the findings do not violate Einstein’s theory of special relativity. The photons carried no information, ensuring no cosmic speed limits were broken.
A Divisive Discovery
The concept of “negative time” has sparked both fascination and skepticism. German theoretical physicist Sabine Hossenfelder criticized the work in a widely viewed YouTube video, arguing, “The negative time in this experiment has nothing to do with the passage of time — it’s just a way to describe how photons travel through a medium and how their phases shift.”
Angulo and Steinberg counter that their research addresses critical gaps in understanding why light doesn’t always travel at a constant speed. While controversy surrounds their paper’s provocative headline, no serious scientist has challenged the experimental results.
“We’ve made our choice about what we think is a fruitful way to describe the results,” Steinberg stated, adding that while practical applications remain elusive, the findings open new avenues for exploring quantum phenomena.
“I’ll be honest, I don’t currently have a path from what we’ve been looking at toward applications,” Steinberg admitted. “We’re going to keep thinking about it, but I don’t want to get people’s hopes up.”
