The cycle of time in the universe

Is it possible that the time flowed not rectilinearly, but cyclically? In the philosophies of ancient India, China and the Middle East, there was the idea of "eternal return", "a circle of time". The cycle of time in the universe took place in the philosophy of ancient Greece. Something similar we find in some modern cosmological models of the universe. In contrast to time, "beginning", we consider a variant with a cyclic time, i.e., a time, closed "by itself".

The cycle of time in the universe took place in the philosophy of ancient Greece

In 1949, at Princeton University, the well-known mathematician Kurt Godel actually gave a talk "Time in the General Theory of Relativity". In this report, he argued that the cycle of time in the universe is indeed possible, that is, there are possible geodesic lines closed in time for a certain class of its models. Translated into ordinary language, this means that, under certain conditions, the universe can return to its original state and in the future repeat exactly the cycles that have been passed again and again.

If the cycle of time in the universe were to be fulfilled in reality, it would practically mean that the expansion of our universe in the future should be replaced by compression to an infinitely high density. After this, a new expansion would begin, during which the same cosmic objects would arise. At some stage our Earth would again be formed, and on it again the same events would repeat and the same people would be born who would live exactly the same life as their counterparts in the preceding cycle... And so an infinite number of times.

Many years later, the well-known theoretical physicist S. Chandrasekhar once again considered in detail the model of the time cycle in the universe proposed by Godel, and came to the conclusion that the closed trajectories arising in it are devoid of physical meaning. However, in this case Chandrasekhar used the method of "physically reasonable" choice, connected with arbitrary intuitive assumptions.

The fact that the cycle of time in the Universe with a return to the past described by Godel is impossible in the model proposed by him (such is the opinion of Chandrasekhar) does not exclude such a possibility in general within the framework of the general theory of relativity. In other words, from the fact that cyclical returns of the universe to the past are impossible in the special model proposed by Godel, it does not yet follow that there can not exist a world with closed time lines at all. But the fact that this is really so, it is still necessary to prove...

If the time cycle in the Universe really existed and the Universe, in fact, periodically passed through states with the same initial conditions, then all the same absolutely concrete situations could practically not be repeated. Such repetitions are possible only from the point of view of classical physics, which reduced all the infinite variety of world phenomena to purely mechanical processes, to the "iron" connection of causes and effects. However, the science of the 21st century has convincingly shown that random events play an important role in the motion of matter. They are not able to change the general orientation of the evolution of matter, but thanks to them, the specific situations that arise during this evolution can differ substantially even in the case when the starting points of development were absolutely identical physical states.