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?
This sounds like an XKCD what-if that ends with an explosion that could deafen god himself.
Like, if it just pops into existence, “static” relative to the sun, it’d all slowly fall into the sun. The solar system is ehhh 100 AU wide, atmospheric density’s about 1 kg per cubic meter, 1 AU is ~1.5e11 m… volume of a sphere is 4/3 * pi * r^3… that’d be 4.5e39 kg of gases, or basically 500,000,000 times the current mass of the sun. So, at a wild guess, probably enough to form a black hole? But it cannot be good for the inner solar system either way. Especially not if we work out how an Earth-shaped column of that gas falls into the sun with Earth in the way.
(Edit: Sagittarius A* is only 4e6 solar masses. 5e8 is borderline supermassive. Things would go poorly.)
If it spins instead - if it’s all playing nicely with the orbits of each planet and the general flow of the asteroid belt - we probably don’t all die fantastically. At least not for a while. We can assume it’d be a plane instead of a sphere, maybe 1 AU thick, as if the sun had rings. I don’t think it’d just diffuse out into the cosmos? Once all that mass is orbiting, you’d only lose the weird exceptional atoms that reach the edge with a bunch of energy and then don’t hit anything for a zillion miles. That also happens at the top of Earth’s atmosphere, and we’ve got gravity keeping it in check. So let’s just hand-wave that this situation lasts, like, at all.
Those bands in the rings will experience friction. Any speed differential has consequences, and I do not want to think about the computation requirements for that kind of fluid simulation. I think at worst they’d separate. They can’t all take the same angular velocity because that’s not how orbits work. They might fuck up the planets moving through them? Like, I don’t know much about astrophysics, but when a planet has rings it’s not because things went well for the satellites in that range.
Actually that highlights how the planets would have the same issue as the sun, if a bunch of mass magically appeared overhead, in their reference frame: it’d fall. Air doesn’t weigh much, but when you hand-wave an entire gazillion miles of it, that adds up. We’d have problems well before the atmosphere started to outpace the entire solid mass of Earth.
If this atmosphere orbits each planet, the way the whole shebang orbits the sun - you’re back to speed differentials. Just thinking locally: there’d be different spin for air that refuses to fall toward Earth, and air that refuses to fall toward the moon, and somewhere in the middle those two streams would meet. Or - at best! - they wouldn’t quite meet. The gaps would separate themselves. You could maybe do a cool sci-fi setting with that, but your space 747 would need to zoop clean out of Earth’s sky-ocean and catch the moon’s.
Oh. And I don’t think sunlight would be visible through one hundred and fifty million kilometers of atmosphere. At least, until the sun slurped up a couple yottatons of it, at which point we’d have whole new problems.
You say that air doesn’t weigh much but 1 atmosphere of pressure is already 14.7 pounds pee square inch at sea level. That’s enough to flatten a steel barrel if a vacuum is pulled inside it. The consequences of increased atmospheric pressure at the earths surface alone would be nothing short of a mass extinction event. Every planet would become a gas giant, and potentially even brown dwarfs if not stars in their own rights. I bet Saturn and Jupiter would ignite at the very least.
If we thought global warming was bad, the heating of the gas accretion combined with the insulating effects of a thicc atmosphere would likely completely eradicate all life.
On the plus side, it would be one hell of a show before all life burns out of existence.
Yeah, this question kinda undersells how it’s sprinkling a couple aspirational rocks into an enormous cosmic gas cloud, rather than providing those rocks with a quaint environment. Even the provolone-slice model that’s 1 AU thick is only lighter by two orders of magnitude. It’s one million times the total mass of everything else in the solar system. Spreading it on as thickly as our soupy atmosphere, where even certain mammals can flap hard enough to hunt in midair, would have an impact on world events the way a period impacts a sentence.
Yeah, the Sun is IIRC something like within an order of magnitude what would be required.
kagis
https://public.nrao.edu/ask/what-is-the-critical-mass-at-which-a-star-becomes-a-black-hole/
EDIT:
https://en.wikipedia.org/wiki/List_of_most_massive_black_holes
Yeah, based on your estimate and that list, it looks like it’d make the solar system into something like the 90th-largest supermassive black hole that humanity knows about.
The center of our galaxy, the Milky Way, has a black hole that’d be dwarfed by what our solar system would turn into.
https://en.wikipedia.org/wiki/Milky_Way
https://en.wikipedia.org/wiki/Sagittarius_A*
So the Sol system would instantly become about 100 times more massive than Sagittarius A*.
I don’t know if all of that mass would actually wind up in the resulting black hole – I assume that the collapse of all that nitrogen and oxygen and such coreward would induce nuclear fusion and a supernova would blow some of the mass of what had been the Sol system outwards.
Yeah, sounds like most of the mass may get blown away before some of the remaining can collapse into a supermassive black hole.
Apparently this would have about five times the mass of “Scary Barbie”.
https://en.wikipedia.org/wiki/AT_2021lwx
That’s maybe a hundred million solar masses, and mindbleach is figuring that we’re dealing with about five hundred million solar masses.
So assuming that the gas composition isn’t a factor here, I’d guess that we’d probably wind up turning ourselves into the largest explosion that humanity has ever observed in the universe, as the nitrogen undergoes gravity-induced nuclear fusion.
EDIT: Actually. Hmm. There’s some portion of hydrogen gas in the atmosphere. According to this, it’s mostly in water vapor. It’s not much:
https://byjus.com/question-answer/what-percentage-of-the-earths-atmosphere-is-hydrogen/
But I guess that it might be sufficient to start undergoing fusion prior to the nitrogen and blast most of the stuff apart prior to the nitrogen undergoing fusion.
Ditto for the carbon in the carbon dioxide, even if the hydrogen isn’t enough.
With front-row seats.
Does this mean if we had a huge empty sphere in space, not around a star, (empty Dyson sphere) it could form a black hole with all the mass at the outside edge of the sphere?
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.