Well yes, the chemical substance acted as a catalyst causing changes in brain processes. A sharp blow to the head or neurological illness can sometimes produce the same kind of thing. That is what I meant by a chemically fueled reality rendering engine. Changing the physical parameters of the mechanism through chemistry causes it to process information differently than normal; releasing some inhibitors, enforcing others, and causing the end product of consciousness to manifest in a nonstandard manner.
You have to remember that the sense of time passing is just as much a brain generated effect as anything else in consciousness.
You are describing the source of all religious experience. I think one thing that is important to realize and from your first sentence, ("I do think the brain is just organic, chemical mush which creates for whatever intelligence is, a picture of what our senses take in." ) it seems that you do and that is, "That bit you think is experiencing all this, that bit is just as much a product of the chemical mush of the brain as the things it is experiencing." Therefore, when the brain is altered in such a manner that it begins processing abnormally, the silent observer, the awaress, or however you want to express it, is fundamentally altered as well. For substances to somehow open the mind to actual alternate realities, as opposed to creating them whole-cloth, it seems to me that this silent observer would have to remain unaltered. It isn't though, nor could it be.
The human mind is incredibly creative and complex beyond what the sub-process we understand as our awareness can contain. It is another case of the subset being incapable of comprehending (describing) the super-set to which it belongs.
I acknowledge that our senses and brain/mind systems are only capable of presenting a representation of what is in the real world around us and therefore there is much that we cannot know about the true nature of reality that constitutes the superset. So I have room in my world view for strange anomalous phenomena and other realities (so to speak) but I have to acknowledge that we are restricted by the performance characteristics of the perceptual apparatus of our central nervous system.
I think it gets back to the notion that the whole of reality (as it is experienced) is contained within the individual and that we are actually invisible immaterial beings creating (through the same mechanism that creates and manifests dreams and hallucinations) what we casually percieve as the real world and ourselves in it from information gathered by our senses of the invisible, immaterial reality that we exist within.
