Physicists Have Reversed Time on The Smallest Scale by Using a Quantum Computer

It's easy to take time's arrow for granted - but the gears of physics actually work just as smoothly in reverse. Maybe that time machine is possible after all?

An experiment earlier this year shows just how much wiggle room we can expect when it comes to distinguishing the past from the future, at least on a quantum scale. It might not allow us to relive the 1960s, but it could help us better understand why not.

Researchers from Russia and the US teamed up to find a way to break, or at least bend, one of physics' most fundamental laws on energy.

The second law of thermodynamics is less a hard rule and more of a guiding principle for the Universe. It says hot things get colder over time as energy transforms and spreads out from areas where it's most intense.

It's a principle that explains why your coffee won't stay hot in a cold room, why it's easier to scramble an egg than unscramble it, and why nobody will ever let you patent a perpetual motion machine.

It's also the closest we can get to a rule that tells us why we can remember what we had for dinner last night, but have no memory of next Christmas.

"That law is closely related to the notion of the arrow of time that posits the one-way direction of time from the past to the future," says quantum physicist Gordey Lesovik from the Moscow Institute of Physics and Technology.

Virtually every other rule in physics can be flipped and still make sense. For example, you could zoom in on a game of pool, and a single collision between any two balls won't look weird if you happened to see it in reverse.


https://www.sciencealert.com/physicists-have-reversed-time-on-the-smallest-scale-by-using-a-quantum-computer