The main stumbling block with analysing the idea of witnessing another reality, is ensuring that what is experienced, is not a product of the malfunction of the human brain, and its ability to perceive, cognise or interpret. An individual could be suffering from any number of internally generated psychological and physiological conditions, that interfere with the usual process of sensing the material environment. Such divergence away from normal function in the brain (and body), obviously leads to an internally generated view of the physical world, that does not actually exist ‘out there’. If a group of people appear to share a ‘visionary’ experience, it cannot be rejected out of hand, that all concerned are suffering from a perceptual ailment, or that the group is engaging in a ‘cult-like’ activity involving peer pressure, mutual conditioning, and interpretive reinforcement (i.e. a group hallucination). From a scientific perspective, these issues cannot be ignored whilst attempting to establish the theoretical principle of the existence of different planes of reality. Of course, belief systems effect how the world is perceived simply because that is one of their primary functions, but ‘belief’ does not necessarily equate to correct perception or interpretation of reality. Although theoretical physics postulates that other dimensions may exist (i.e. ‘String Theory’ and ‘Quantum Theory’, etc), these realities are mathematical probabilities, and not the product of sensory observation in the usual or mundane sense. In other words, the only manner in which these realities have been understood to exist, is through the use of numbers as cognised by the human brain. This is very different to the structure of religious or spiritual visions of other realities, which always appear to be like this (mundane) reality – but ‘ideal’ in nature. This can be ‘ideally’ good or bad, depending upon belief ad circumstance, but there is no scientific reason why other dimensions should be in anyway ‘familiar’ to human beings and their cognitive sensory array (which has evolved within a particular environment), or even ‘perceptible’ to the human mind in the ordinary sense.