A person knows that time always runs from the back. The human experience is perceived from yesterday to tomorrow. For physics, this time arrow, which seems obvious, becomes diffuse in quantum scales. In the field of relativity and quantum mechanics, there is no difference between the future and the past because the main equations that describe the universe are temporarily symmetrical.
The time direction does not influence the behavior of most physical phenomena. If the time suddenly took place tomorrow towards yesterday, a planet would continue to orbit its mother star in the same way and a ball would be shot up after receiving a kick. Mathematically speaking, moving back in time is equally possible to do it forward.
Where are the time arrows
Since the concept of temporal symmetry is so counterintuitive and, at the same time, visible in mathematical equations, numerous attempts have been made to test it and find exceptions to the rule. The most famous case is that of the second law of thermodynamics: an orderly system always tends to disorder. Here, the arrow of time goes forward and cannot go in the opposite direction. A cup can fall and break, but never a broken cup will bind again.
There are other more complex examples, such as the so -called “quantum arrow.” Instead of obeying the principle of entropy and disorderly, subatomic particles lose coherence and their quantum properties, such as overlap, disappear. In this scenario, it also seems that the direction of the past to the future is the favorite.
A recent physicist effort from the University of Surrey to verify the time arrow in open quantum systems (those who interact with the environment) has led to a blunt but expected result. They also found temporal symmetry. The finding, in the words of one of its authors, Andrea Rocco, suggests that the behavior of a quantum system is equally possible if the time arrow has the opposite direction.
Only the present imports, for any time arrow
The scientists used a particle model under high temperatures in an open container and analyzed them according to the Markov approach. This method indicates that the closest state of a system depends on its current state and not on the sequence of its previous states. In other words, the future only depends on the present and not on its history.
The experiment, published in Scientific Reporthe found two time arrows in his open particle system. The system components moved indistinguishable, whether the time passed from the past to the future, and in the opposite direction. The particles disorderly, of course, so the second law of thermodynamics was not violated, but the result was the same.
“Any state of thermal equilibrium for a progress trajectory is also a thermal state of equilibrium for any inverted trajectory in time, and entropy increases in both directions,” says research.
Finally, work speculatively suggests that this behavior can be extrapolated to the cosmological time arrow. We live in a universe where time flows from the past to the future, but it is also possible that it occurs in a opposite way without violating physical principles.
“This would imply that two opposite arrows of time would have emerged from the Big Bang, which in turn would explain the maintenance of time investment symmetry, despite the consequent dissipative nature of the universe. We would live in one of them, where dissipation and increased entropy are common experiences, but without realizing the existence of the other alternative possibility, ”concludes the study.
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