What's the most dense a planet could be and still be livable? How does water factor into the overall density of the planet. Is something like an osmium or iridium core even be possible/realistic?
If you had a planet 1/4th the size of earth but wanted the same or similar gravity, would that be possible or livable? Not talking probable, just possible.
How different would a gravity of 6, 7, or 8 be compared to 9.81 like earth?