Let’s suppose we could dump enough “breathable” air (whatever that means for humans) into the solar system that it filled the spaces between planets.
What would happen?
A - I imagine it would then become possible to fly airplanes between planets, perhaps balloons? Would space travel become easier or harder?
B - According to another lemmy post, we would start to hear sound waves from the sun (A constant jackhammer sound - delightful)
C - Each each planet become the center of some mega cyclone (like the Jupiter storms, but bigger)?
D - At some point the air above us wouldn’t be pushing down onto the earth at sea level, could we survive the additional pressure?
So, something becomes a black hole when there’s too much mass in too small a space.
For a given amount of mass, that’s the Schwarzschild radius:
https://en.wikipedia.org/wiki/Schwarzschild_radius
A Dyson sphere would need to avoid collapsing its matter into something smaller than the Schwarzschild radius; if it did, then it would become a black hole. If they don’t collapse, then no.
I don’t know how Dyson spheres are supposed to avoid gravitational collapse.
goes looking
Okay. Looks like what they do is to basically consist of a bunch of solid satellites that are in orbit but don’t collide. They aren’t actually a single solid object; the name is something of a misnomer:
https://en.wikipedia.org/wiki/Dyson_sphere
https://old.reddit.com/r/AskScienceFiction/comments/zqg6e/is_a_dyson_sphere_actually_possible_or_would_it/
But a solar-system-sized sphere of gas can’t do that, because you can’t keep the orbits of the gas from smacking into each other.