Hi Gumpi,
Believe me, before starting ayp I didn't buy into the esoteric either. And even now, I don't believe these things in the sense that they are necessary or even definitely "real". What do I think of them then? Well, I think these practices start a process in the body and this results in these experiences. I am apt to believe the process is one of purification or dropping baggage that we have either accumulated or have been born with.
I think the kind of experiences we have is related to where the purification is taking place. So, for example if the part of the brain that is being worked on is the occipital lobe (back of head-visual center) then the experiences might include what would be termed illusions or hallucinations. Now, if the purification is happening in a area where we have for example a strong emotional connection to a diety or ishta and that is stimulated along with the visual cortex, we can easily have dramatic visions of our chosen savior, etc...... Similarily, if the vestibular area (balance) along with proprioception (ability to sense our position in space) is affected, the feeling of levitation might arise.
The thing is that the brain and its processes are so complex that multiple ares (each responsible for different things such as emotions, thoughts, motor control, perception, vision,......)are involved and thus it really isn't as simple to say that a purification in this part will cause certain "perceptual experiences". This type of reductive thinking is easy for those involved in the sciences (including me) but we have to just be comfortable with knowing that we cannot completely know the mystery.
I have never been a visual person and I think those that are, are more likely to experience these phenomena. I have been practicing for almost two years now, and honestly I cannot visualize the sushmna one iota. But the silence, oh there is no doubt about the silence.
So some of us will have dramatically different types of experiences and honestly, I think it might be possible to go far without seeing many "visual" fireworks. Heck, we (you and I) might have purified these areas in previous lifetimes or might just be born lucky!(honestly, now I think it is a blessing because it would be so easy to go overboard or into ego fantasy land if I can do something or see something that almost all other humans cannot).
Just the same, I don't doubt these experiences can actually happen. For a second think about the fact that we are on this big watery planet which is hurling through space and orbiting the sun, etc.... and dang the illusion that we should know everything should come crashing down. Again the brain and its abilities are so vast that you simply cannot deny that almost anything is possible. Though we do see the rarity of these things lately It seems there is more talk of siddhi's etc... although I don't hear too many people claiming complete mastery and control over it. Rather, it seems like a occurrence that is only somewhat in their control.
So, the experiences are more signposts in the sense that they confirm that the purification process is active. I don't think the experiences are related or necessary in the sense that they are mostly the dust of a room that is kicked up during the cleaning process.
Truly, the only experience I care about is happiness. Now, a lot of people say they are happy so you can't trust even your mental interpretation. So how do you know ? As Jesus said, Ye shall know them by their fruits. So I implore you to pay less attention to levitation etc.... and instead pay more attention to how do you spend each moment of this existence. Keep practicing, and by God, the results will speak for themselves. The truth/happiness have to be the greatest Siddhi of all.
take care,
eitheway
p.s If along the way we start levitating or gain other siddhi's, we can discuss it then. Until then I think it is just fodder for the mind.