Anyone care to define the 'spiritual world'? Does it exist within or outside of Nature? If it exists outside of Nature how are some people able to perceive it? If it is in 'another dimension' (please define 'another dimension')how are some people able to perceive it? Presumably, if some people are able to perceive the 'spiritual world' there must be a flow of information from that world to our world - how does that work?

You see anyone can ask lots of questions! I think you'll find that Science can provide lots of answers to the questions that you have posed, GfS (see TIA's excellent post above) and where it doesn't have answers - well, it doesn't have answers yet (and, in some cases, may never have answers).