Question: How do you find out the spiritual world exists? How do you get there?
Answer: Well, in near death experiences you find out rather quickly. Your physical focus is greatly diminished by whatever caused your experience, and you are confronted with a whole new dimension of life. We are spiritual beings focused in a physical world, when the physical focus diminishes, or stops, we automatically return to the spiritual source from whence we came. A near death experience is one of the fastest ways I know of to reach the spiritual world. But there are other ways also. Some include: sleep, meditation, relaxation, anything that reduces physical focus, causes unconsciousness, or death.
It may seem ironic that both relaxation and violent accidents can cause the same phenomenom as a near death experience, but when you think about it, it's not so strange. Dying is the relaxing of physical focus, it is just "forced" instead of "allowed." If you want to experience the spiritual, I recommend you allow yourself to relax through meditation.