Did it happened before?

In our daily life we are busy at doing our jobs, studies and all the other stuffs. We hardly think about some unanswered questions. Tough we are living in a modern age, having modern tools and technologies but still we are unable to answer a lot of questions. What we can do is just give a hypothetical idea of any phenomenon which are not answered yet. There are many of these mysteries and one of them is "Did it happened before? "
                   You can relate this question like you are doing something and suddenly you just got a sense like it happened before, in a exact same way same place and same manner. It's just a fraction of seconds and you feel like this thing happened to me before. But it didn't. This brings us to a serious question why is this happening. what is the reason behind this. Did it really happened before or its just a vision?
                    Now to get the answer we need help of science. In recent pasts scientists believed that there is only one universe in which we are living. But recent studies shows that there can be multiple number of universe, or more specifically, multiverse. So if there are multiple universe then it's also possible that two of them are running at same time, at a same manner after big bang. We can denote them as twin universe or parallel universe. In parralel universe theory our twin universe is running at the same time and doing the same things exactly as ours. That means if you are listening music right now then your doppelganger ( The same person who is your replica or more specifically you in other universe) is also listening the same music at the same time. These two universe are synchronized so accurately that there is no time lapse of the events which are happening all the time in both universe. But sometimes it got lapsed. The synchronization between the two universe is interrupted and thus other universe get ahead of our by just for a few moments. Which means our other self of the other universe is experiencing a event few moments earlier than you. And you are experiencing the same thing few moment later. But the time lapse is so small like a fraction of seconds and again the universe get synchronized. In this process of synchronization you and your doppelganger who are connected with each other got the vision. That's why you think that this might happened before. Yes, this was happened before but not with you. This was happened with your doppelganger, and you are just sharing his experience just after a fraction of seconds.
                   This is why we got vision of something. The universe is full of mystry and unsolved puzzles. There are many things undiscovered. We as human being just trying to solve the puzzle to unlock the chest of knowledge of the mysterious universe.

Real and Actual are two words which we occasionally distinguish from each other. In minor sense they are same but in broader sense of view they are not same all the time.
                      We mark those things as real which we can see in our naked eyes, which follows the fundamental laws of physics and psychologically accepted. As a example if we take a piece of candle, everyone will realize that this is a candle because it is accepted by our general understanding. This is realization. But if we want to dig farther we will see something which is more true in sense of science. And from here comes the view of actualization.
                      We can easily understand the 'ACTUALITY' if we consider the most controversial hypothetical theory - 'String Theory'. Lets take the same example again, the piece of candle. If we want to know what are the constituents of the candle, we can easily say atoms and molecules. If we break them up we will find protons, neutrons and electrons. If we farther break these we will get Quarks and Leptons which are the building blocks of proton, neutron and electrons respectively. Here the understanding of modern physics stops. But according to String Theory Quarks are not the fundamental particles. The Quarks are made up of strings(closed or open). These strings are so tiny that we can not see them in any way. Everything in this universe is made up of these strings and they vibrate at a different frequency. Like for a stone,  water , gas for everything these vibrate at different frequencies which make them distinguishable. But string theory only works at multi dimensions and we live in 3 dimensional world. So, there must be another dimensions which we can not see. Scientists suggested that there are two types of dimensions, big dimensions which are visible and small/tiny dimensions which we can not see but exists everywhere. Now only the strings can travel through the dimensions. So it is possible that the strings which made the candle in other dimensions that may not be a candle, that maybe something else. This is actuality.

                                         
                                                      fig: Strings(closed)

                        In short we can say whatever we see in daily life, whatever we marked them as our understanding, whatever we say real that maybe something else in other dimensions. That may not be actual. That can be something else, something beyond our understanding.