Not sure if you'd consider it a technical or scientific insight, but I mentioned this on another HN post a while ago: I was able to visualize four dimensional

Not sure if you'd consider it a technical or scientific insight, but I mentioned this on another HN post a while ago: I was able to visualize four dimensional structures on LSD. I can't see it "instinctually" anymore, but I had a vision of our universe as the 3D surface of a 4D hypersphere, and from that perspective it's subjective whether you consider the entirety of the universe inside of you or outside of you. After coming down I thought it was probably some nonsense that my brain dreamt up, but I analogized it as a 2D surface of a 3D sphere and it makes complete sense. Drawing a circle on a sphere and calling one side of the line you draw the "inside" is completely subjective—we just tend to call the smaller side inside. If you grow the circle to the greatest meridian of the sphere, which side is now "inside"? Is my brain on the inside and the universe on the outside, or is the universe on the inside and my brain on the outside? I also kept seeing (when I say "see", it isn't the type of hallucination that appears like a real object in front of you, these all form in my mind's eye but are more vivid than what I can usually visualize) these grid-like, branching "corridors". I'm not sure what the best term for it would be and it may have not been 4 dimensional per se, but I don't think the way it's laid out would work in 3 dimensions. It was like I was floating in an intersection with rows (x), columns (y), and aisles (z) passing through me. A lot of this is hard to visualize when not tripping.