My thoughts re: the shamanic three worlds and Dr. Sue's take on there is only one world.
In an October workshop workshop with Dr. Sue Morter, author of The Energy Codes, she talked about how there are no other worlds. We are all here at the same time. Light and physical being all part of a continuum, a spectrum on the same plane. This idea is very much how I see the traditional three worlds of the shaman. Understanding that there is only one world and relating to it from the shamanic perspective only requires the ability to slide your perspective. It is how I have come to know the shamanic practice of having one foot in both worlds.
When you travel to one of the traditional shamanic three worlds, you are not going anywhere. You are simply moving into a lighter consciousness perspective. This helps you to go there at any time. Just move the meter to the lighter vibration. Move your awareness away from your physical plane toward your energetic plane. You are both at the same time.
For me, the shamanic perspective is one of sliding the ruler in order to bring healing, wisdom, clarity, all manner of things, from the light into the physical. The earthiness of shamanic tools and their deep connection to nature, ground the wisdom from the light plane into our physical plane. When I work with flowers, drums or rattles, I am allowing the energetic qualities of nature and the physical world to ground the healing into this plane. It is both at the same time. The physicality of the drum (sound vibration hitting my ears, the skin of the animal and the tree from which it was formed) can be used as a way to slide the perspective to the lighter plane while staying in the physical plane. You are in both at the same time.
We humans have been trained and we've become accustomed to perceive our physical being mostly, but our light being is here too. You can slide your awareness, back and forth between the physical and the light. Sometimes it's beneficial to be more in the physical plane - having sex, driving the car. Sometimes it's beneficial be more in the light plane - searching for truth, making life decisions. Sometimes you want to be in the middle of both - making love, parenting, healing with your hands. Neither is better or worse and it isn't an either-or proposition. The path of the Sacred Ordinary is about living with a sliding perspective.
An interesting related take-away from that workshop offers a perspective slide regrading the things you have been told are not real, e.g. fairies, Lemuria, giants, etc. Dr. Sue said, "What if you could allow both to be present?" I like that. What if there were two or more perspectives? What if your perspective was broader than where you are right now? It's about being able to slide your perspective. Sometimes from the physical to the light and sometimes from the fixed and known to the wider field of allowing and not knowing. Sometimes the slide isn't left or right as much as it is both--opening you to a broader perspective.