Bob Shaw's SF novel "The Ragged Astronauts" plays with this idea. A major plot point is a journey to a neighbouring planet - by balloon. The novel indicates tha

Bob Shaw's SF novel "The Ragged Astronauts" plays with this idea. A major plot point is a journey to a neighbouring planet - by balloon. The novel indicates that the laws of physics are different, e.g. a scientist character indicates that π = 3 (IIRC). [0] https://en.wikipedia.org/wiki/The_Ragged_Astronauts https://en.wikipedia.org/wiki/The_Ragged_Astronauts