I would like to read your explanation. It's not an easy question.
Fair enough. You know about "fluid", and all that entails right?
Strictly on the physics of fluid, we have two atmospheres on this planet.
One is 25 times denser than the other, but both are made up of the same thing, namely molecules containing hydrogen and oxygen. Both are made up of alot of similar molecules. And both sustain life.
If we were to be seen by another species, they would marvel at the dual nature of our planet.70 percent of our planet is covered by water, and we have an outer atmosphere that is over 50 miles thick. We are blessed, and protected, and provided for. We do not have to fight like hell, just to survive...
We are bouyed by one atmosphere, and covered by another.
We are spinning at over 1000 miles per hour, orbiting at over 17,000 miles per hour, and flying through space at over 50,000 miles per hour, yet our two fluidic spheres keep us cozy.
Am I close?
This "star ship" is perfect.
BTW, forgot nitrogen...sorry