Well I aren't informed about ET's, because I never seen one and most likely never will hehe. The truth is hard to find, if the answer lies outside of our world of our current understanding of it, because it aren't part of our reality. If nobody has the information you look for, well, plan B is here, since I only know aliens as multidimensional beings who we can interact with :=)
But, if I lack information, i need an answer too, because I have this need to know by whatever the force is behind to want to know it. Then this nature state of being "curiously", is good to have. Anyway I cant answer your question directly. But if you truly want to find an answer to your question. Well then, I would start to search after the answer within us, or by questioning, about it in dreams/astral travels etc. Just too see, what my answers will be that I 've come across, hehe.
Else maybe with a bit of luck and by tapping into our shared conscious field around Earth, where the information will be downloaded and decoded by itself to an inner knowing, and suddenly, you have this footprint in you, ehh, like a "thought-impression" that wasnt there before - like unseen forces, because you can be manifesting the thought of knowing it (sent/receive)..
Anyway, maybe someone have the answer to your question here. If not go do plan B