IF the brain were to outlaw the laws of physics, then the laws of physics would not be what they are, and would be amended to include such possibilities until the reasons why, ie laws as to how that is performed are deduced (until which the best theory goes).
For me, everything has a reason, but reasons for many things relate to position in the universe, time, etc, ie its all soo dependant on a massive sum of tiny changes caused by properties of atomic particles..
So in the end, asking why anything is, is silly, eg there is no point in finding a reason as to why, say, a loved one was the one to die (in any general non expected accident, to be clear).
We each seem to have some experiences that may lead us to believe in these kinds of things, especially when we have memories of things in dreams, which later happen.
It can however, be that such a deja-vu, is a mixup in that the thing you experience (which has similarities to previous experiences, possibly amalgamated), while you experience, is stored in memory by two threaded streams, such that during the experience, it appears as though those experiences are already there, or certain smells, touches, sensations, sounds etc, and when this happens, they are sent out to the mind again, as some 'memory' of a previous event.
On the other hand, it could be something far more complicated than that, as that kind of idea could be propsed thousands of years ago, were it not for faith in spirits, gods, ghosts, demons etc.
Afterall, its not like you rememmbered the Deja-Vu the day after.. You don't remmember it until it happens.
..I had one that stretched over 2 years once.
No one could believe that i felt as though i had dreamt the intro to a tv show 2 years before the show came out.
