Theoretical physicists Alan Guth (who is one of the creators of the inflationary model of the universe) and Sean Carroll of the Massachusetts and California Institute of Technology, respectively, proposed a model of a world in which time flows backwards. The Daily Mail reports.
Scientists used a simple model to describe a possible alternative Universe in which the future and the past have swapped places. In their work, physicists used the thermodynamic concept of the arrow of time, which emphasizes the inequality of the past and the future.
According to this concept, the direction of the flow of time in the system coincides with the growth of entropy (the transition of the system from a more to a less ordered state). For example, it is almost impossible to return the system to its original state after mixing coffee and milk in a cup.
In their work, scientists became interested in the question of why the entropy of the Universe should be low at the moment of the Big Bang (the beginning of the reference time for the life of the observed world). For this, Guth and Carroll considered a system consisting of a limited cloud of particles with arbitrary speeds.
Scientists have followed the evolution of this world in infinite space and time (infinite universe). It turned out that arbitrary initial conditions led to the fact that half of the particles began to propagate beyond the cloud, thereby increasing the entropy of the system.
The other half, on the contrary, began to tend to the center of the cloud, which meant a decrease in entropy. Having passed the center of the cloud, these particles began, like the first, to spread outward the region of space initially occupied by the cloud, which increased the entropy of the system.
The scientists noted that the total increase in entropy from the two clouds occurred even if the direction of the flow of time was reversed, since all the particles would eventually leave the limits of the cloud they originally occupied.
In the system considered by physicists, the direction of time was formed by chance. This is confirmed by the formal independence of the equations of physics from the direction of time. Zero entropy corresponds to the initial moment, after which the system evolves into the past or future.
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Scientists do not know what happens in a particle system, where there is no definite direction of the arrow of time (between the center and the outside of the cloud). The model of scientists supports the existence of a multiverse in which each of the worlds can have different directions of the flow of time.