because we only witness the longitudinal or linear virtues of time and because we receive sensory signals which must travel in one direction to reach our physical individual centre of perception/our brain we are only able to see in that one direction , and given that our potential is governed by what we believe is possible within the reality we have come to know which in turn is dictated by what we know only of the past , so we can only get at best fleeting glimpses into any alternate or parallel reality , these glimpses are restricted to less tangible realms of physical perception than the ones we have honed and mastered into our existence .