Quantum mechanics is complicated and for the average person, much of it doesn’t make any sense. This study of some of the smallest and most fundamental aspects of how the universe works is fastening, and often counterintuitive.

A paper, which has yet to be peer reviewed, is a great example of this. In the paper, the team of researchers says that they observed photons that were beamed into a medium, but exited that medium before they entered it.

That’s right, almost like time travel.

Josiah Sinclair from the University of Toronto is one of the scientists whose experiments were used in the study (but was not involved in the study), explained to Scientific American:

“A negative time delay may seem paradoxical, but what it means is that if you built a ‘quantum’ clock to measure how much time atoms are spending in the excited state, the clock hand would, under certain circumstances, move backward rather than forward.”

The experiment sent photons into a cloud of atoms that were near absolute zero temperatures. From there, the photons would sometimes be absorbed by the atoms, sometimes pass through, and sometimes they would pass through without being absorbed.

When the photons would pass through without being absorbed, the researchers found that the atoms were actually still being excited in the same way as if they had been absorbed. When the photons were absorbed, they would then be emitted from the atoms without any delay, which is to say before the atoms could de-excite.

The researchers say that these experiments do not change the way they understand time, but do say that ‘negative time’ does have more significant than one understood.

If you thought that was interesting, you might like to read about the mysterious “pyramids” discovered in Antarctica. What are they?