TORONTO, Canada: Scientists have long known that light can sometimes appear to exit a material before entering it — an effect dismissed as an illusion caused by how waves are distorted by matter.
Now, researchers at the University of Toronto, through innovative quantum experiments, say they have demonstrated that “negative time” isn’t just a theoretical idea — it exists in a tangible, physical sense, deserving closer scrutiny.
The findings, yet to be published in a peer-reviewed journal, have attracted both global attention and skepticism.
The researchers emphasize that these perplexing 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 the term “negative time” might sound like a concept lifted from science fiction, Steinberg defends its use, hoping it will spark deeper discussions about the mysteries of quantum physics.

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 they return 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 — meaning a duration less than zero.
To visualize this concept, imagine cars entering a tunnel: before the experiment, physicists recognized that while the average entry time for a thousand cars might be, for example, noon, the first cars could exit a little sooner, say 11:59 am. This result was previously dismissed as meaningless.
What Angulo and colleagues demonstrated was akin to measuring carbon monoxide levels in the tunnel after the first few cars emerged and finding that the readings had a minus sign in front of them.

The experiments, conducted in a cluttered basement laboratory bristling with wires and aluminum-wrapped devices, took over two years to optimize. The lasers used had to be carefully calibrated to avoid distorting the results.
Still, Steinberg and Angulo are quick to clarify: no one is claiming time travel is a possibility. “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 following strict rules.
Instead of adhering to 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 doesn’t violate Einstein’s theory of special relativity, which dictates that nothing can travel faster than light. These photons carried no information, sidestepping any cosmic speed limits.

The concept of “negative time” has drawn both fascination and skepticism, particularly from prominent voices in the scientific community.
German theoretical physicist Sabine Hossenfelder, for one, criticized the work in a YouTube video viewed by over 250,000 people, noting, “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 pushed back, arguing that their research addresses crucial gaps in understanding why light doesn’t always travel at a constant speed.
Steinberg acknowledged the controversy surrounding their paper’s provocative headline but pointed out that 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,” he said, 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,” he admitted. “We’re going to keep thinking about it, but I don’t want to get people’s hopes up.”
 

LONDON: It’s that time of year when crowds of pagans, druids, hippies and tourists head to Stonehenge in Britain to celebrate the winter solstice, with the shortest day and the longest night in the Northern Hemisphere.
Thousands are expected on Saturday at the megalithic circle on a plain in southern England as the first rays of sun break through the giant stones that make up one of world’s most famous prehistoric monuments.
Rain has been forecast but there is no doubt it won’t be able to drown out the drumming, chanting and cheering.
Beyond the fascination of the ritual, the eternal question may still linger in the back of the minds of many visitors: What was the real meaning and purpose of Stonehenge?
The site has been the subject of vigorous debate, with some theories seemingly more outlandish, if not alien, than others.
This year, those gathering will have something new to discuss.
In a paper published in the journal Archaeology International, researchers from University College London and Aberystwyth University say that the site on Salisbury Plain, about 128 kilometers (80 miles) southwest of London, may have had some unifying purpose in ancient times.
They base that on a recent discovery that one of Stonehenge’s stones — the unique stone lying flat at the center of the monument, dubbed the “altar stone” — originated in Scotland, hundreds of miles north of the site.
What was surprising was that it came from so far away. It was long known that the other stones come from all over Britain — including the so-called bluestones, the smaller stones at the site that came from Preseli Hills in southwest Wales, nearly 240 kilometers (150 miles) away.
That varied geology is what makes Stonehenge unique among over 900 stone circles in Britain.
“The fact that all of its stones originated from distant regions ... suggests that the stone circle may have had a political as well as a religious purpose,” said lead author Professor Mike Parker Pearson from UCL’s Institute of Archaeology.
It may have served as a “monument of unification for the peoples of Britain, celebrating their eternal links with their ancestors and the cosmos,” Parker Pearson said.
Whatever its original purpose, Stonehenge today retains an important place in Britain’s culture and history and remains one of the country’s biggest tourist draws — despite the seemingly permanent traffic jams on the nearby A303 highway, a popular route for motorists traveling to and from the southwest of England.
Stonehenge was built on the flat lands of Salisbury Plain in stages, starting 5,000 years ago, with the unique stone circle erected in the late Neolithic period, about 2,500 B.C.
English Heritage, a charity that manages hundreds of historic sites, including Stonehenge, has noted several explanations — from the circle being a coronation place for Danish kings, a druid temple, a cult center for healing, or an astronomical computer for predicting eclipses and solar events.
So as far as symbolism and unification go — maybe Stonehenge really was a Mount Rushmore of its day?