The cosmologist Alan Guth, who developed the theory of the expanding Universe, and the famous astrophysicist Sean Carroll declare that other "bubbles of the universe" may exist next to our Universe, where time does not flow forward, but backward.
Famous theoretical physicists Alan Guth and Sean Carroll suggest that the Big Bang could give birth not only to our Universe, but also to its "mirror" copy, where time, for observers on Earth, flows backward rather than forward, as they said in an interview New Scientist magazine.
One of the foundations of modern physics and cosmology is the concept of the so-called "arrow of time" - the postulate that time in our Universe moves exclusively in one direction, from the past to the future. In other words, we move through four-dimensional space exclusively in one direction along the time axis, and it is impossible to "rewind" time back.
From the point of view of physics, this is manifested in the fact that over time, the disorder, chaos of the Universe, a state that scientists call entropy, is steadily growing. For example, this process is manifested in how the state of the energy of the Universe changes.
So, immediately after the Big Bang, it was evenly distributed over it, and at the end of the life of the universe, the cosmos will represent a "zero" from the energy point of view, an absolute void, filled with superdense accumulations of energy - black holes.
As many cosmologists today believe, the Big Bang did not occur from scratch - it was the result of the compression and death of the predecessor of our Universe. In this case, as Alan Guth, the famous theoretical physicist from the Massachusetts Institute of Technology (USA), says, the question arises - if the entropy of the newborn Universe was low, how could it be born from the "debris" of another Universe, where it was most likely high ?
Guth and his colleague Sean Carroll from the California Institute of Technology in Pasadena (USA) found a potential solution for how to "restart" the universe - they suggested that the Big Bang could give rise not one, but many universes, in which time will go in two different sides.
The cosmologist and physicist demonstrated the feasibility of this idea using a simple computer model of the Big Bang, in which a cloud of small droplets-particles, each of which had a random speed and direction of motion, played the role of the future Universe.
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Over time, this cloud will split into two or more parts - its inner part will have low entropy, like our Universe, and the outer one will have high entropy. For external observers, time in the inner cloud will go the same way as in our universe, and in its outer part - in the opposite direction, moving from a state of high entropy to a higher order.
Thus, our universe may have neighbors in which time flows in the opposite direction for us. The inhabitants of these worlds, as Guth and Carroll emphasize, will not feel this - they will feel that time is flowing in a "normal" direction. Contact with them, as the scientists note, will not be possible in principle, "since they will exist in our past, which will not allow us to talk to them, and they will not be able to talk to us because we will be in their past."
It remains unclear what will happen in the middle of this "cloud", where the entropy will simultaneously rise and fall at different points. Uncertainty about the behavior of this part of the "infinite multiverse", as Guth notes, is the main reason why their work has not yet been published in the scientific press.