I actually answered this when I mentioned cross referencing. It's also observation and experience, how does that NOT show the answers are correct. You seem to be under the impression this is all just an assumption and I've made it clear it is not.
The issue here is that cross referencing with others offers little verification in this case, it could just be showing a degree of uniformity in the brain. Certain parts of be brain activate we experience similar things. Two models, two explanations how do you determine which is accurate?
Well certainly not a science experiment in a lab that is for sure, so again this is personal observation and cross-referencing which gives it strength. Spirituality is repeatable as a practice, that's because it's an actual reality that exits and can be learned from. Personally, I verify my own experiences with other sources and references and this is about the extent of what can be done with the nature of it....being "outside" or away from the physical perception so you have to follow that fact all the way down to what would apply to us and how.
Why not scientific equipment in the lab? It can show what is happening in the brain, which is useful after all. Again, how do you verify these experiences aren't products of the brain? It is certainly interesting that our experiences match, but then NDE's also have a surprising amount of variation. Ultimately it could be argued that the similarities stem from the similarities in the form and function of the human brain, while the differences stem from those factors that make one a unique personality, why isn't this a valid argument?
This one I answered, it's commonsense. There would be no experience outside the physical brain and body, period.
But it could certainly seem like the was couldn't it? The brain could certainly send signals telling us that we're experiencing something outside the body/brain couldn't it? How can we verify that this isn't the case?
Many things because it's an incredibly diverse reality/realities. People, places, things or any facts pertaining to it....all the things you would observe or could observe in the physical only spirituality must be cultivated you just can't look around with your physical eyes and expect to manifest anything. You have to awaken that part of yourself through participation, nevertheless anything within the God-worlds or multiverse can be experienced, but this would be called soul travel and you have to learn how to operate outside the body. But other than that your soul will pull back to the very first reality that is beyond this one when you leave the physical body, that universe is called the astral plane. There are multiple planes or multiverses that can be experienced depending on the individual.
What are your means of being certain this isn't constructed by the brain?
It depends on what it is you want to observe or learn. There are spiritual principles that can be applied to the self, spiritual practices that you can do to help loosen the grip of your focus on squarely the physical perception. Basically you can move your attention or awareness away from your body and observe from another point of observation but the point is for you to get involved and learn from it. Since your soul has layers that cover it called subtle bodies or spirit body you are able to observe or experience through any one of those layers just like you observe through the physical layer currently.....these "layers" correlate with an existing plane or universe which exist parallel to this one. So as you leave each layer you experience with the correlating world and the first layer outside this one would be what most people pull back to which is the astral but this is only the first layer…..this is how people have spiritual experiences and why they have NDE's ect ect….because the soul can literally leave the body at any time either through death or through practice regardless of beliefs.
Not to flog a dead horse, but why couldn't any of this be simply a construct of the brain? You don't seem to offer any form of verification other than cross referencing with others experience, which doesn't seem to show the brain can't be responsible.