Science is the name given to all our imaginations that can be transformed into mathematical equations and are thus susceptible to being true or false. This is the beauty of science that it has given the wildest imaginations of mankind an acceptable and even respected forum for discussion.
One such theory that springs out from the physical sciences is the theory of parallel universes. The theory advocates one of our wildest fantasies to be a fair possibility in the complete picture of the universe. Imagine having a doppelganger in another part of the universe or other universe altogether which is only a brane world away from you. All those episodes of Fringe, The Flash, Rick and Morty and Steins Gate must manifest in the minds of those sci-fi lovers and yet the aspiring physicist have keen understanding of the implications of such a story. I myself find it amusing and amazing if such a reality may exist. It gives you a kind of relief thinking that whatever you were not able to achieve or do in this universe, one among infinite of your coexistences may have done that in some other universe. It gives you a sense of satisfaction and even a feeling of achievement that might have been missing earlier. But I am afraid that on careful analysis of the logic behind the likeliness of existence such parallel universes seems to be a bleak possibility. One finds themselves amidst the emptiness of their unique existence.
Although I do not deny the possibility of existence of multiple universes but them being almost similar to ours seems to be a far-fetched idea.
This is thus a simple criticism of the parallel universe theory where we are imagined to have our replicas.
If we consider multiple universes each having a version of us then it will become logical necessity for all the versions to follow an exactly same path and a similar fate. This is because if they do not do so, they would only end up contradicting themselves. This will be clear if we imagine a situation in terms of genetic quantum realities to simplify the problem.
We know that the genetic code of an individual is precise enough to manifest unique individuals and unique personalities. If it may have been otherwise we would have been witnessing exact replicas to the most fundamental levels where even the consciousness would resonate between multiple individuals. But it is not so. Philosophers may argue that this is only due to the problem of induction but unless proved otherwise the result remains the same.
Now because these multiverses may reflect same individuals in different settings, it will become absolutely impossible for an individual to exist in two universes without the same set of chromosomes that they possess in this universe. If it happens so otherwise it will only lead to a quantum change and the resulting personality will be distinct from what it is in this universe. So it follows from absolute necessity from the genetic laws that my mother and father in this universe would have to be the same, the ones they are in all the other universes.
But philosophers and physicists have stated possibilities where the replicas of individuals in other universes may or may not follow the same path they follow in this universe. This may lead them to associate with other persons in other universes rather than forming the same couple to give birth to the same offsprings.This means that at a point where even if once this anomaly occurs it will give birth to a butterfly effect that will gradually alter the path of evolution of the alternative universe completely from what it follows in this universe. This will give rise to much more anomalies and conflicts between the reflecting universes. So if there has to be same individuals in different universe they will have to follow the exact same path to the very minute details in order to be reflection of each other. Every other possibility would only lead to other possibilities that will make these universes not at all similar. If such an arrangement is to be considered than their remains no need for universes that are perfect replicas of each other. Only one may suffice.