> The Karman line has nothing to do with lift, it's just an arbitrary, round number. I think you got this upside-down. The Kármán line is named after an engine

> The Karman line has nothing to do with lift, it's just an arbitrary, round number. I think you got this upside-down. The Kármán line is named after an engineer called Theodore von Kármán who studied the problem of how high aeronautical flight is possible theoretically. That has everything to do with lift, and speed an orbiting body needs to stay in orbit. That is the Kármán line. Then yes of course organisations need clear and bright lines for things like "when do we give someone an astronaut badge?" For that different organisations come up with nice round threshold numbers. And those numbers have nothing to do with lift. But those numbers are not the Kármán line. They are just convenient approximations of it for administrative purposes. It's like if a country's tax authority declares that for tax purposes you shall calculate the area of a circle using the first 5 digits of PI. That doesn't mean that suddenly the PI become not a transcendental number. It is just an approximation for practical reasons.