In your thought experiment, you are presupposing many common factors; we can understand this better perhaps because you are positing "3+ dimensions" so we can t

In your thought experiment, you are presupposing many common factors; we can understand this better perhaps because you are positing "3+ dimensions" so we can think "the dimensions we see plus a couple more" which makes it seem like the other community is a superset of ours. Likewise, in your former, generalized statement, it works if you continue to think of "our universe". The entire notion of anything remotely resembling a brain, or anything like what we understand to be cause and effect (like, nurturing something to keep it functional, or even the very concept of "functional"...) existing in the host environment (whatever that means! :) ) makes the abstract statement devoid of meaning.