Provided we give the right hints, the reader will create the world in all its stunning detail. So, it is not necessary for us to imagine everything that the reader might want to experience . The reader will fill in the blanks. It is the writer's responsibility to make sure that those dots are lined up properly, so that the reader doesn't end up imagining a world that doesn't go with the story the writer wanted to tell. If your story uses modern physics you should endeavour at least not to use it wrongly.
Fiction is ultimately about people.
I always get arguments about this point. A lot of SF writers will disagree with it. Early stories used the existence of the ether, or N-rays, or broadcast power, which were all seen as solidly possible at the time. The reality you describe ultimately has to be at the service of the story. Starting from the opposite premise is the single biggest reason I've seen for stories failing at the level of world building.