I'm starting a peice up in my head, but I have a question. It is in an alternate universe with an alternate world, landforms, etc. But it has physics similar to Earth's, as I am not a celestial being capable of altering perception in itself, so that would just be a better thing to do. That being said, would there be any restrictions as to how things can form, the height of things, density, gravitational pull on landmass, etc., is there any resources I can find that would guide me with these guidelines of earths universe? Laws of physics almost.