15/01/2025
Quantum experiments have just demonstrated the existence of "negative time," challenging conventional perceptions of time in physics.
Using lasers to study photon interactions with atoms, the team measured how long atoms remained in an excited state after absorbing light. Surprisingly, their findings revealed a duration less than zero, a phenomenon they describe as "negative time."
Confusing? Picture it this way:
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.
While this concept of negative time sounds like science fiction, the researchers stress that it reflects quantum mechanics' peculiarities, not a violation of Einstein's relativity. The photons in the experiment didn't carry information backward or faster than light, avoiding any implications of time travel.
The discovery has sparked both intrigue and skepticism.
Critics argue the term "negative time" may mislead, with some likening it to a shift in photon phases rather than a true reversal of time. However, the team stands by their results, arguing that their research addresses crucial gaps in understanding why light doesn't always travel at a constant speed and view the description of their findings as an opportunity to deepen understanding of quantum behavior.
Though the findings currently lack practical applications, they open the door to exploring unexplored aspects of light and matter. As physicist Aephraim Steinberg acknowledges, “We’ve made our choice about what we think is a fruitful way to describe the results,” inviting broader discussion about quantum phenomena and their interpretation.
Learn more: https://arxiv.org/abs/2409.03680