I’ll try to arrange the question in parts in order to understand what the first claim is that you’re rejecting.
1. Life on another planet in the universe is not unreasonable.
2. If life exists on another planet, then technological development more advanced than ours—whether because of a faster pace or because of a longer period of activity—is entirely reasonable.
3. Such life, with advanced technology (not much more than what we have today), would be capable of successfully impersonating God, both in the past and even today.
4. If they are capable of such an impersonation, and a revelation appeared in our world, then maybe it was them.
5. The possibility that they are the ones who revealed themselves is no less reasonable than the possibility that the Creator of the world is the kind of being who reveals Himself and indeed did reveal Himself.
Thanks in advance!!

A little physics also wouldn’t hurt. Does your honor know what the distance is to the nearest planet/star system (Alpha Centauri), and how much energy is required to traverse that distance?

Speculations are not subject to physical constraints.
As for the question itself, I’ll explain further why there is no question here.
The fundamental question, the physical-theological one, is: how did everything that exists here come into being? If you attribute that to aliens, the question will arise: who created them? And if they don’t need a creator, then they are God. In the end, there has to be something that creates everything and itself does not need a creator. You can call it an alien if that calms you down.
In addition, a tradition has come down to us that that same God who created the world is the one who revealed Himself and gave the Torah. He said so. So are you suggesting the possibility that maybe it wasn’t Him, but His cousin, who is also called God, and that he is the one who created the world? Or perhaps He just lied? You understand that this is exactly like the speculations about demons or flying cats that I described above.

Thank you for the answer, but I think you didn’t explain any more than in the previous answer, and all I claimed in the question was that a revelation of distant life-forms (created by God) that advanced technologically is really not just speculation about demons, and it is no less reasonable than making the leap from an abstract God to a God who reveals Himself. In any case, thank you for being willing to answer.

This is not at all a question of what is more reasonable. As I explained, these are not two alternative possibilities.

Rabbi, I don’t understand.
Let’s assume there are aliens, and that they are far more technologically advanced than we are, such that they can reach our galaxy.
Would your answer change then?
If not, I’d be glad to know why. Doesn’t that change the force of the miracle?
If so, why? There’s a degree of skepticism in that.

Sorry. You simply don’t understand what I’m writing. There’s no point in this discussion. I’m done.

“Questioner and Responder” is not the questioner “Sinai.”

Sinai’s argument sounds reasonable. I’d be glad if the Rabbi could explain more, because I actually came here because I had thought of the same argument.

If we discover very soon that the probability that aliens visited Earth is high, wouldn’t that weaken the claim about the revelation at Mount Sinai? By the way, there’s in general a big difficulty with revelation itself, since you can always attribute it to some natural volcanic event or the phenomenon of a pillar of fire from the sky, whose name I forgot.
I hold by the argument that if it were really so easy to turn a natural event into a supernatural one in the eyes of an entire people, then many nations would have a tradition of mass revelation. Which we do not see.

Well, then you answered yourself. And I answered too. So what are you asking?