The bitter truth is that according to all we believe to know, scientifically, any meeting with an alien from another planet would mean that our current knowledge of astronomy and physics is not complete (I'm sure it is far from that, btw.), or false.
Because either ET has come from a planet close enough to allow linear space travel in our understanding, which would mean there are planets carrying intelligent life in our closest neighbourhood in this galaxy, much closer than we assume, and we have not discovered these planets, leaving our observations capacity in shame.
Or ET has come from a damn far away place indeed, in which case linear travel would have been impossible, so his transportation means would make mockery of what we consider to be safe and proven knowledge in physics.
Or he has come from somewhere completely different, a parallel universe, a different dimension, a different time. In which case again we would need to realsie that our physics knowledge is far from complete.
In any of these cases, it would mean that we are in the inferior position, facing ET. And what knowledge do we have that allows us to assume that "they" have not so primtive motives like we humans have, and that we should not be worried about "their" superiority? History books, anyone? Lessons to be learned from them?
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Almost all to be seen on this pic, more than 99,999...% - is just empty space, and the matter we get an idea of to exist in the bright spots - again is consisting of just empty space.
And although it is just empty void, this void nevertheless seems to have a superimposed structure.
However, I will not talk anybody into trying to imagine the sheer size and dimension of the void within the "cells" of this structure, formed by superclusters. Because only at times it is a relativisation of our own egos and earthly business. More often, reaching too deep into this void with our imagination, is an experience of sheer horror. Space is not friendly to our lifeform, nor is it a home, or a harbour, or of any comfort. It just is void. And void kills our soul if we stare into it for too long.