Do you k now why we fly? because someone thought that, against reality, we could.
My take on this is that, man has observed birds flying for many thousands of years. The reality has always been that with wings and a sufficient density of air, a creature can fly.
The rules governing flight meant that flight was not possible for man unless he equipped himself properly and aligned himself with the principles of aviation. With trial and error, much of which involved observing birds in flight, the Wright brothers finally met the requirements for flight.
Those requirements have always existed and have not have not changed since man mastered them. Our perception of what was possible for man has changed but reality has stayed constant.
Our perception is subjective and often erroneous. Should the earth loose its atmosphere then aviation would no longer be possible nor would breathing. That reality would affect everyone and be an objective change.