I don't feel philosophy, semantics/semiotics, mystical experimentation (not dogmatic religion) or consciousness change stands too far removed from Quantum Mechanics because of the varieties of thought or experinece which exist and the scientific interest (psychology) behind those areas of thought. I think QM makes more sense to me on a personal or human level when viewed in the context of psychology.
As far as physical quandrys like "why am I still here" my main one was when I was about 8 years old we were going to see the ET movie in the theater later that day so I decided to bike around the neighborhood a bit to relieve the anxiety of waiting to go. I turned the corner to get back to my place and a guy shot out of his garage and backed right over me. He didn't see me at all or hear my yelling but luckily for me the handlebars of the bike jammed and he couldn't back up any further so he stopped and got out to see what was going on. He was really wigged out when he saw that a kid was trapped under the car but I didn't get hurt at all, not a scratch and it only damaged the grips on the handle bars. I wonder if he looks when he backs up these days?
I've had a number of "mystical" astral projections or OBEs or whatever you like to call them. Always they have been self-induced through the classical methods, I've never had any spontaneously occur. Many times I've taken the easy route and get there via some good tea, I enjoy that sort of mind-magick/creative visualisation. As an artist/writer I find these kinds of adventures very inspiring. One standout experience for me in the recent year was after a extensive study of egyptology and classical necromancy. I had spent an evening meditating on some egyptian anubis and bast statues, breathing deeply and slowing my heart rate as low as it could go until I went dark. I underwent a sensory/visual experience of being embalmed, mummified, ressurected and unwrapped by temple preists and raised to witness a new constellation forming in the sky outside the tomb. As the sun rapidly came up in the vision I also "woke" from the whole state which lasted some 20 minutes perhaps after "going dark". What it means other than I'm a weirdo I couldn't say. But I attribute that sort of "freerange mystical experience" to my intensive studies at the time combined with the trance techniques, and good tea!
I have to say, with what is known about neurology, I've lost a lot of faith in OBE's, although there are some exceptions that stick out to me. For a while I smoked a lot of "legal smoke" blends with all sorts of random constituents to go dream walking a few years back. The results were largely bizarre and immemorable. I had lots of flash visions of things like my house, but all the door frames were made of roller skates and the like that would stick in my field of view, then fade slowly as I tried to sleep.
The thing that really got me, however, was when I started dreaming lifetimes. From what I've read about Salvia(never tried... successfully), it was very similar, except less symbolic. In these dreams I would be going about my day, very mundane, trivial stuff, except things would be different. It was as if I was visiting separate timelines based on decisions I had made in my life, such as "what if I had stayed with that one Ex of mine" or, "what if I had never moved out of the house I was raised in?" Sort of things. It was how completely UN-dreamlike they were that really made them stick out. One in particular was so intense, flashing through my mind, an entire lifetime of events and experiences, all my life, just a little different, until one day I went to get a book from a shelf in my old room, circa age 17, and then woke up in my studio apartment in Houston.
Very strange stuff, it was actually after those series of dreams that I became very involved in trying to understand relativity, QM, and the MWI of QM.
Speaking of bike survivals, I found this out after High School, but when I was 6, I fell while trying to learn to ride a bike and jabbed the butt of a handlebar right beneath my ribs. It hurt so bad I became the only 6(then 7, then... 12) year old who didn't know how to ride one. I still have a smidgeon of scar from then. Now, the reason this was allowed to happen and my parents never encouraged me to try again, is because two weeks after that, another boy, also 6, did the exact same thing, and died of internal bleeding.
I feel that many of the "unexpected / instantaneous" OBEs, NDE's or even the ever popular "UFO sightings" or "Alien Abductions" are simply unexpected activations of the pineal gland. This is where DMT (an analog similar to Salvinorin-A or Salvia) and other chemicals are naturally created in the brain. DMT is one of the strongest psychedelics known, changing both visual perception and thought in radical ways though it's effects generally do not last very long. This gland I feel, is where these sorts of visionary "mystical" and near death or other archetype ridden "mental experiences" take place or at least originate and travel through our nervous system. Mystical exercises such as fasting, meditation on specific images and ideas, yoga (pranayama), lucid dreaming experiments, sensory deprivation or overload, etc are ways to activate the Pineal. In this day and age I regard the UFO and alien greys as merely a new emerging archetype (following Jung). Possibly it can indicate a terror of the future? As much as I've wanted to see a UFO or alien I never have had the chance, maybe I don't want it or fear it enough?
On death I think we may receive the largest rush of DMT as the gland fires its last and this perhaps explains the expression of "life flashing before my eyes" as all our past perceptions come back in a flood of visions like a movie montage, as I've heard it described. Near death events may trigger the same biological blast from the gland and may explain how people come out of a near death experiences a "changed person", as one is also said to be after a psychedelic or mystical experience. My great uncle nearly died and had to have emergency surgery. He was never a religious man however after that he began to volunteer at the church as an usher (he never even went before). He never discussed what had happened and I was not into neuroscience when he was still alive as I was a kid but today I would dearly love to ask him all about it. I have gone as far as to say this gland seems to me where "we" (our ego or "self") reside. But I have absolutely no proof of that other than my own off the wall deductions since science has never found where "we" reside in our brains if indeed it's not just an amalgamation of the whole or something else entirely.
As schizophrenics are often said to be visually hallucinating I would like to see some blood tests to see if someone in a full schitzophrenic state and someone in a mystic trance state has a higher amount of DMT than the average person. For some interesting research into this area have a look at: DMT the Spirit Molecule by Strassman if you haven't already. I don't personally believe that any of the experiments I've performed on myself ever found me actually leaving the carcass and actually moving about in any sense other than in the "mind's eye". Not being of a religious bent I never could attach any sort of cosmic or religious significance to any of these kinds of experiences but I don't discount other people's deductions to the contrary from their own experiences as we all perceive things like signs and symbols (semiotics) differently.
For more info on this sort of subject see: Programming the Human Biocomputer by John Lilly and just about all psychology works by Timothy Leary.