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raydiatian

Here’s a fascinating question:

If an LHC collision were to form a blackhole,

1. How long would it last

2. Could we detect it

3. How much mass would need to be collided to suck in Earth?

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1 kg black hole will last 8*10^-17 seconds[1]

[1]: https://en.wikipedia.org/wiki/Hawking_radiation#:~:text=The%...

Could it find some equilibrium environment to be able to suck as much matter as it radiates. So it could last longer (?)

It only has the gravity of a 1 kg object and is extremely small, so it's not likely you'd be able to find an environment where mass is going to be getting jammed into it at quadrillions of tons per second even ignoring the fact that it's sort of a continuous nuclear explosion — it's radiating all its mass energy at a rate a few million times higher than the output of the sun in the ballpark of a star actively going nova.

> How much mass would need to be collided to suck in Earth?

A significant fraction of the mass of the Earth. Black holes don't "suck" any harder than other objects of the same mass.

An Earth mass black hole has a radius smaller than the plug in your bath tub. It would take a very long time to cram the Earth down such a small hole.

An Earth mass black hole in someone's bathtub wouldn't be such a walk in the park. The mass interaction would rip Earth apart.

It's not a practical possibility. The black hole wouldn't last long and would be too small to actually absorb anything. It's the equivalent of asking if a nuke would set the atmosphere on fire.

Even a "large"ish primordial black hole would probably just pass straight through the Earth without anyone noticing.

Strange matter on the other hand...

Remember that Strange matter is only dangerous assuming a specific range of values for its surface tension, otherwise it's harmless and doesn't catalyze the conversion of normal matter into Strange matter.

What even is the smallest primordial black hole possible to still exist here 14B years later?

I'm not sure. Somewhere around 10^12 kg of initial mass would be evaporating today (1). So perhaps there is no meaningful minimum, only a minimum initial mass. If it's just about to evaporate, it could perhaps be arbitrarily small. Earth is ~10^25 for reference.

(1) https://en.wikipedia.org/wiki/Micro_black_hole#Expected_obse...

A black hole is just a "normal" mass object. If the Moon was replaced by a black hole of the same mass, there'd effectively be no change except for it not being reflective like the Moon.

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