I wonder what the chances are if there's a few of them within the Boötes void. It's pretty big.

> maybe it's better off if we were completely oblivious.

even that would be a slow death I suppose. Don’t think the Earth would just vanish instantly.

I'd wager such an encounter is way more likely to result in any of:

1) the Earth being flung out of the Sun's orbit

2) planetary orbits becoming disrupted such that an encounter with another planet over the coming years or millennia becomes likely,

2.1) which could eventually have the same "flinging away from the Sun" effect,

2.2) or (unlikely, but possible) result in a collision

2.3) or result in the Earth being shredded into asteroids

2.4) or other planets suffering that fate and then showering the Earth with dangerously-large asteroids over a period of decades or centuries until it's nearly, or actually (think: outright crust liquefaction from impacts) lifeless.

than the Earth actually getting swallowed up, by at least an order of magnitude.

IOW, the most-likely "we're all dead" outcomes for us, from a close encounter with a massive rogue anything really, including a black hole, might take years and years to play out.

Sounds like a plot of Seveneves by Neal Stephenson

Schwarzschild radius of a 10 stellar mass black hole is ~20 miles. It would need to be pretty close in order to resolve optically.

Yet they detected a lone black hole in the article. Maybe detection isn't guaranteed though?

Detection typically requires exceptionally rare circumstances - which if looking at a dataset the size of the visible universe, typically turns up several examples if we look hard enough.

But any specific random example, is often brutally hard to see.