I'll start off by saying I have ZERO scientific background. I'm very interested in having a general working knowledge of physics and such, but I'm more concerned with creative applications for writing at the moment. Ever seen a movie with way too many scientific impossibilities? Yeah, I'd like to avoid more of those. Anyway, is it at all possible for a human-habitable planet to have a pull upward, so that things would fall into the sky if left untethered, while other things such as land masses have just enough mass to be at equilibrium and float in the atmosphere? Say this planet was formerly like Earth, but something happened to cause this scenario and humans were advanced enough to adapt. Could perhaps a high-density "bubble" surround the planet, dense enough to offset the gravitational pull the Earth's mass provides? So basically, what scenarios would make this possible? And what environmental consequences might make life impossible? If life is possible, what are other consequences within the environment? Thanks for any help.