You, of course, have also met them, and once decided to simply trust their smart authors, because they probably had a headache from the theory of relativity, which means they at least understood something about it. 
Two observers, unaware of each other's presence, conduct the same double-slit experiment. Alice tracks the passage of particles through the slits, Bob does not. Alice sees projections of the slits on the screen. What does Bob see: an interference pattern or also projections?
Of course, it would like to give definitions of the fundamental properties of matter in the strict form of combinations of the basic concepts of “the same” and “the other”, according to the rules described in this fundamental thread: 
But, why not speak out when you are amused by people’s misunderstanding of the simple things. Judging by the fact that this is not widely discussed and therefore did not catch eye in the feed, even if one of the leaders spoke out, it did not penetrate the mass consciousness.⮯
Yes, yes, I know. The theory of waves has been worked out for a long time and perfectly, all the required mathematics is known and obvious, gravitational waves absolutely correspond to it, all the great predictions have come true exactly, what else is there to talk about.
In short:
So, are there other universes?
@elonmusk We visited the Moon half a century ago and since then have done quite well without far space flights. Is it possible that such a waste of funds and efforts is simply explained by the fact that one enthusiast was carried away by the idea of giving humanity a multi-planetary?
Like everything in the information universe, fundamental interactions are the derivatives of the metric of the universe. It is it that determines their number - four - and the basic features of each of them.
2/19 To understand what the universe is, first need to clear yourself of the jumble of absurdities that the BBT has turned cosmology into. Take any theory, and if it has in anamnesis the Doppler interpretation of redshift - forget it, this theory is wrong.
Belief in aliens is no different from religion: it is just as unscientific, because it contradicts the special theory of relativity. 
2. The idea for this new thread came in a dream. The brain, accustomed to everyday perception of reality, is not satisfied with a strictly formal answer, and, without asking the owner's opinion, seeks more worldly arguments for the same conceptual basis. 
