[justsomeshmuck]

It's theorized that there is a grapefruit-sized black hole orbiting our sun in the outer reaches of our solar system with a mass of 5 to 10 earths. A black hole spontaneously appearing in your home small enough to not rip apart the entire planet immediately would probably be too small to notice without some sort of detection equipment.

[codethief]

> It's theorized that there is a grapefruit-sized black hole orbiting our sun in the outer reaches of our solar system with a mass of 5 to 10 earths.

Source: https://arxiv.org/abs/2004.14192 (There was also a pretty good discussion about it here on HN.)

> would probably be too small to notice without some sort of detection equipment.

What makes you think that?

[justsomeshmuck]

https://academic.oup.com/mnras/article/152/1/75/2604549?logi...

Theoretically, black holes can have a mass of the tiniest fraction of a gram which would be unimaginabley small. It's my own speculation that you wouldn't be able to detect that with a naked eye.

[codethief]

Thanks for the link!

> you wouldn't be able to detect that with a naked eye.

What if you touched it? No idea what the spacetime would look like near a gram-sized black hole with lots of heavier matter surrounding it but I suppose there would still be pretty severe tidal forces.

[sliken]

Anything coming anywhere close to the event horizon would be removed, and some fraction of that mass would be converted into energy an irradiate the surrounding. So the best you could hope for is that it's moving fast, leaves a hole in you and leaves fast before you die.

Keep in mind that event horizon isn't a shell, just a point at which your future (which is in the singularity) is certain.

[codethief]

> Keep in mind that event horizon isn't a shell, just a point at which your future (which is in the singularity) is certain.

Yeah, exactly my thought. Then again, we're silently assuming here that spacetime would pretty much look like one of the vacuum black hole solutions plus some additional matter (our body) near it. That doesn't seem too likely, given that our body is much heavier and can't just be treated as a test particle. OTOH it doesn't seem too likely, either, that the actual spacetime would look completely different: There will surely still be a black hole and an event horizon.

[paulmd]

Ah yes, the tachyon detection grid. ;)

https://memory-alpha.fandom.com/wiki/Tachyon_detection_grid