“Its because given the laws of physics”
As we know them. That doesn’t mean they are absolutely accurate. They are “laws” only because we haven’t witnessed phenomena that are not explained by them. Also, whose to say that matter and energy act the same everywhere in the universe?
We’ve witnessed lots of things that are not explained by them.
When that happens, the “laws” get extended, or modified, or come to be seen as a special case of a more general continuum of behavior, not normally seen in everyday life.
That’s how we got relativity, and quantum mechanics, and quarks, and radioactivity, among other things.
OK. Show me one sane Chairman of the Department of Physics at any credible university to come forward and postulate in a peer reviewed journal or at a conference of physicists that he or she believes that UFOs are real material entities from another star, that aliens from another star have visited earth and postulate a theoretical equation to back his theory. Science fiction is amusing and even inspiring, but it simply is not real.