Is it normal to wonder what would happen if gravity was reversed?

I didn't think of this as an absence of gravity, just it flowing in the other direction. Was it always this way or did it just happen overnight? If it was always this way, I imagine all the water would be in the sky and humans would need both gills and wings. But what would the core of the earth do? Would it fracture and fall to the sky? And dear god, volcanoes! Now I'm going to have nightmares, thanks.