Not to be disrespectful, just to discuss, don't you think it has to do with the chemicals the brain releases during death or near death experiences? Ketamine can replicate it to some degree and people have reported things just like that during trips.
All good! If this topic is of interest, extensive research covering all of these points has been compiled by a researcher named Kevin Williams.
Near-Death Experiences and the Afterlife discusses about Scientific Evidence of the Afterlife , enjoy all our post about this!
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What I can say is that human history over the past several centuries has tended to alternate between cultures of religious superstition and scientific materialism. Both perspectives make sense to the respective followers from the inside, but the tribal rivalry between them means that neither side is open to the perspective of the other. The result is incomplete.
Only when the most advanced scientific understandings (quantum field theory, advanced consciousness research, etc.) points to the same reality as the most essential spiritual understandings (nonduality) does a complete picture come together. However, that picture is so insanely radical that it defies commonsense notions we normally take for granted. Things like the world being objectively real, ourselves having an identity as individual people, ideas of mortality, us being separate from each other and so on.
Some psychedelic experiences entail similar themes to NDEs, involving losing a sense of individual self, being one with everything, euphoric love, etc. These cases are legitimate experiences, albeit temporary, because they tap into the underlying reality which is also accessed through NDEs,
kensho spiritual awakening experiences, spontaneous mystical experiences, advanced states of meditation, etc.
To focus on the exclusively material aspects of physical brain activity in order to prove a reductionist/materialist world view is analogous to trying to prove a dream is real within the dream, or trying to prove a VR world is real without being open to removing the headset. An open mind is essential.