What is reality? What are the requirements for something to be called "real"?
Let's consider an example. Would we call the tragical events at the end of Shakespeare's 'Romeo and Juliet' real events? - Certainly not, because they were not historical. There were no persons called Romeo and Juliet in 16th century Verona who committed suicide because of their love.
However couldn't there be such a couple in a parallel world, which is completely separate from our world and unknown to us? The events of Shakespeare's novel are certainly consistent and theoretically possible. If nobody from this other world of Romeo and Juliet would ever visit our world and nobody from our would ever visit the world of Romeo and Juliet and no event in each world would ever affect the events in the other world, what would be the requirement for this other world to be considered 'real'?
We could say that it would only be real, if there was also some kind of consciousness in this other world that would be able to experience the events in this world. But even this requirement would be questionable. Is experience by a consciousness a requirement of reality? At least it seems to be a reasonable definition. Otherwise we would have to consider everything, which is theoretically possible and consistent in itself as real. Limiting reality to things that directly or indirectly affect the experience of a consciousness makes therefore sense.
However we have to ask, what makes another consciousness real for us? Would another consciousness in a world whose events never affect us and which is not affected by any events in our world be considered real? Such a consciousness would not even be in any time-related relation to us. It would neither be before, after or at the same time as us, because the concept of time is based on causality. Earlier events affect later events and can therefore be put in a temporal sequence. Event A is earlier than event B and may somehow affect the later event. Events or objects in two separate worlds that never affect each other cannot be put into a temporal order. There is no earlier and later because the temporal order of both events can never be compared and is therefore meaningless.
In the same way two separate consciousnesses in two separate words that never affect each other can never be put into a temporal order. None of the experiences of one consciousness can be considered earlier or later than the experience of the other consciousness. How can we therefore call the consciousness in this other separate world real or not real at all? What is the difference between these distinctions? In fact there is no difference at all. The concept of some consciousness in another completely separate word being real or not real is meaningless, because either option would make no difference for our consciousness. And the distinction between two things that are not different is meaningless, just as the distinction between mercury and quicksilver is meaningless. Mercury is quicksilver. Language allows us to call on thing quicksilver and the other one mercury but in reality it would still be the same. Therefore this linguistic distinction makes no sense.
It is the same with reality. We can linguistically distinguish between something in a completely separate world that does not affect our world and that our world does not affect being real or not real. But this distinction makes no sense. It means the same. There is no difference between both statements making them meaningless.
Reality is always a subjective concept. Shakespeare’s Romeo and Juliet are not real in our world but Juliet is real in Romeo's world, although this statement is meaningless for us since Romeo is not real for us either. He might be real in another possible world, which is separate from us, but the distinction if such a possible world exists or not is also meaningless. If such a world is separate from us and there is never any form of interaction with us, then it is always not real and any further statement is meaningless.
Even the question if Romeo has a consciousness in such a possible separate world is meaningless, because consciousness is also subjective. One consciousness is completely separate from another one. There is no way how a consciousness will ever affect another one. My pain is not your pain, and your pain is not mine. You cannot feel anybody else’s pain. He can tell you that he feels pain and you might see him crying or reacting to a perceived pain but he might also just pretend to feel pain or be programmed to express pain under particular circumstances. His pain is not real for you. The distinction of him consciously experiencing pain or not experiencing it and just mechanically expressing pain is meaningless, because there is no difference between it. His pain is not part of your world and will never be. This pain is not more real for you than the pain felt or not felt in another possible world. The consciousness of others is not part of your reality. And there is no objective reality that would be universally valid. Reality is only a subjective concept.
This concept is far more basic then it looks like because it affects everything, our entire understanding of the world.
Commonly we think in objective concepts. But this is only a theoretical concept that has nothing to do with reality.
If two people look at a football field, which is in our objective model rectangular with angles of 90°. Both observers sit or stand in different positions around the football field. Neither of them sees a rectangular field but they see the playing field with the corner next to them and the opposite corner each measuring an angle close to 180° and the two other angles being extremely small. Since the perspective of each observer is different, they see all different angles. However both observers are sure that they are looking at a rectangular field, although they can’t observe it. Even if they went down right to one corner of the playing field to measure its angle, they would get this angle right but the other three angles would be distorted and differ from 90°. In fact nobody has ever experienced a football field having exactly 90°. It is distorted from any angle we look at it. The rectangular field is actually not real at all. It is a construction in our brain, a model that allows us to make calculations and estimates easier in order to orientate us in the environment. But this objective world, which has no particular observer and where the observer is only placed into it like a figure on a chessboard does mot exist. It is a model derived from our actual observations, which form the primary reality.
So the objectivist or materialist point of view is actually completely unscientific. They believe in the existence of an objective materialist world, where a soul or consciousness is only an illusion resulting from mechanical processes in the objective world denying any validity to subjectivism. However none of them has ever seen this objective world. Their only real observation was from their subjective perspective. So they derived a theoretical objective model in their mind and gave it more validity than their actual observation, which it is derived from. This results in some kind of circular logic that denies the existence of consciousness proving itself from its own conclusions without being based on direct observations. We observe actually only our mind and conclude that the images in our mind have some exterior reality as a cause. The objectivist assumes the exterior world as a given fact and doubts the subjective observation of the images in his own mind that led to the assumption of an exterior world in the first place.
Reality is the subjective distorted football field that each observer can perceive. The objective rectangular field is not real. It can never be observed. It is an abstract model in our mind that helps us to predict how reality will change when we change the relative position in which the observed object is oriented to us. What is real is the way the object is perceived. This is the real world. And our consciousness is the center of the world. What can never be perceived, either directly or through its consequences, is not real.
If we accept this, we suddenly see that there is no actually difference between the different interpretations of quantum physics. The Copenhagen Interpretation means nothing different from the Many Worlds Interpretation. Every other possible world that departs from our world of reality in every moment is not real for us. The distinction between these other worlds existing or not is meaningless. Since they are separate from us and don't affect us they are not real anymore. They are not real just as anything else that can't affect our subjective world is not real for us. The other worlds of the Many Worlds Interpretation are not real in any way since there is no common universal reality where they can substantiate their 'realness'. The separate worlds of the Many Worlds Interpretation will never join together in some way. They are separate forever and therefore not real for us. Whatever we can't experience is always not real. Any further distinction between different forms of not being real is meaningless.