Scientists have long known that light can sometimes appear to exit a material before entering it, an effect that was dismissed as an optical illusion caused by light waves being distorted by matter.

When light enters a crystal or cloud of a substance, it passes through it, interacts with it, and then exits it. But what if you saw the light exiting this crystal or cloud before it even entered it?!


The explanation for this phenomenon lies in the fact that particles such as photons behave in the quantum world in mysterious and probabilistic ways                                      without fixed rules (Wikimedia)

Now, researchers at the University of Toronto in Canada say that through innovative quantum experiments using laser interference, they have demonstrated the existence of “negative time.” It’s not just a theoretical idea, but a tangible, physical reality that deserves closer scrutiny. When photons of light pass through atoms, some of them are absorbed by those atoms and then re-emitted. This interaction changes the atoms, temporarily putting them in a higher energy state, or “excited state,” before returning to their normal state. To put it roughly, it’s like feeling energized after drinking a cup of coffee, only to feel lethargic again.


Experimental physicist Daniela Angelo, lead researcher on the study, poses                        with a device in the physics lab (University of Toronto).

Not a time travel In the new study, which is expected to be published in a peer-reviewed journal soon, the team set out to measure how long these atoms remained in their excited state, and found that it was less than zero, or “negative time.”

To visualize this concept, imagine cars entering a tunnel. Before the experiment, physicists realized that while the average time for a thousand cars to enter might be, say, 12:00 p.m., the first cars might exit a little earlier, say, at 11:59 a.m. The explanation for this phenomenon is that particles like photons behave in the quantum world in mysterious, probabilistic ways, without fixed rules. Rather than adhering to a fixed timeline of absorption and re-emission, these interactions occur over a spectrum of possible time periods, some of which are mundane—say, a second or two—and others that defy everyday intuition.

This is not time travel in the conventional sense, but rather reflects the strange and counterintuitive nature of quantum mechanics, the researchers say in their study. It also does not violate Einstein's theory of special relativity, which states that nothing can travel faster than light, because photons carry no information. Proving the existence of such effects could be of future benefit to quantum computing, where manipulating the quantum states of matter is crucial to improving the accuracy of computers.