A team of Russian scientists have built a "time machine" that can move tiny particles a fraction of a second into the past. In essence, these researchers have just achieved the same principle of time travel by working with electrons in the realm of quantum mechanics, The Daily Mail noted.
Adding to the magnitude of their discovery, the same team established that an electron in empty interstellar space will spontaneously travel back into its recent past.
Driving the study, which appeared Wednesday in Scientific Report, were researchers from the Moscow Institute of Physics and Technology who teamed up with colleagues from the U.S. and Switzerland.
Lead author Gordey Lesovik, who heads the Laboratory of the Physics of Quantum Information Technology at MIPT, explained that the paper was one in a series addressing the possibility of violating the second law of thermodynamics which states that an isolated system either remains static or evolves toward a state of chaos rather than order.
"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," he said.
Most laws of physics make no distinction between the future and the past. Using the collision and rebound of two identical billiard balls as an example of an equation, the study explains that, if a close-up of that event is recorded with a camera and played in reverse, it can still be represented by the same equation. Furthermore, one could not tell from the recording if it has been doctored. Both versions appear to be plausible and it appears as if the billiard balls defy sense of time.
In their report, the researchers described a scenario in which someone has recorded a cue ball breaking the pyramid and the billiard balls scattering in all directions. It would be easy to spot the difference between the real-life scenario from reverse playback. This is where the second law of thermodynamics comes into play. While most other laws of physics do not prevent rolling billiard balls from assembling into a pyramid in reverse, this is not seen happening because it would require an isolated system to take on a more ordered state without any outside intervention. This runs contrary to the second law.
Based on this, quantum physicists from MIPT wanted to see if time could spontaneously reverse itself but instead of billiard balls, they examined a solitary electron in empty interstellar space.
"Suppose the electron is localized when we begin observing it. This means that we're pretty sure about its position in space," said study co-author Andrey Lebedev from MIPT and ETH Zurich. "The laws of quantum mechanics prevent us from knowing it with absolute precision, but we can outline a small region where the electron is localized."
Governing the evolution of the electron state is Schrödinger's equation. There is no distinction between the future and the past but the region of space containing the electron will spread out very quickly. Things tend to become more chaotic and the uncertainty of the electron's position increases.
"However, Schrödinger's equation is reversible," noted Valerii Vinokur, a co-author of the paper, from the Argonne National Laboratory, U.S. "Mathematically, it means that under a certain transformation, called complex conjugation, the equation will describe a 'smeared' electron localizing back into a small region of space over the same time period."
This may not be observed in nature but could theoretically occur due to a random fluctuation in the cosmic microwave background permeating the universe.
The team set out to calculate the probability to observe an electron "smeared out" over a fraction of a second spontaneously localizing into its recent past. They then attempted to reverse time in a four-stage experiment observing the state of a quantum computer made of two and later three basic elements called superconducting qubits.
Stage 1 of the experiment saw each qubit initialized in the ground state, denoted as zero. In stage 2 order was lost. In stage 3, a special program modified the state of the quantum computer so that it would then evolve "backward," from chaos toward order. Stage 4 relaunched the evolution program from the second stage. The researchers found that in 85 percent of the cases the two-qubit quantum computer was able to return back into the initial state.