Lucy's Choice: Let's make Lucifer Parallels!

[robkelk]

Originally Posted by AlexanderHowl

An impact against the near side though could cause a massive ecological disaster as hundreds or thousands of projectiles with an average radius of 100 m could rain down upon the Earth.

That's a very specific number. How did you arrive at it?

Originally Posted by Flyndaran

...
Or it could go full on Cowboy Bepop inhospitable Earth from Moon debris.

That was more than just an asteroid strike - that was a noticeable chunk of Luna being blown off.

And, yes, that would be quite the Lucifer parallel.

Originally Posted by fchase8

That is an awesome story - in The Economist, they said the asteroid should be named 'Rama', after Rendezvous with Rama. It's what made me think of long-term asteroid threat.
...

I like the name it actually received better: ʻOumuamua

[AlexanderHowl]

Fragments 100 m across are the minimum size required to cause massive devestation on a local level, so I use it as an average. Anything smaller might destroy a village or a neighborhood, but 99% of that stuff before 1950 is going to land in the ocean, wilderness, deserts, or farmland, so it is not a concern. You might get a few 1 km fragments as well, but there will be so few of them that they will most likely miss the Earth (if any land, human civilization ends).

[sir_pudding]

Linear size isn't relevant, mass and velocity are. A relativistic black hole the size of a golf ball is still bad news.

[malloyd]

Originally Posted by dcarson

There is no settling down. Things are in ballistic orbits and orbits don't change unless something changes them. So you need a close pass to a larger object. That is a rare event

Well you need to transfer momentum to something. It doesn't necessarily need to be a moving gravity well, a collision, or asymmetric outgassing, could work too.

But no, nothing interstellar is going to be "captured" by the sun without it. By definition the energy you gain falling in from infinity is the escape velocity of the thing you are falling toward. To "capture" an object, its initial velocity would have to canceled out part of the velocity gained by falling toward the sun. But an object far from the sun that starts with a velocity vector pointing away from it was *closer to the sun* earlier, that's what it means to have a velocity away from the sun. That's something on the outward leg of an already existing orbit, not object coming in from interstellar space.

[AlexanderHowl]

A relativistic black hole will pass through the Earth like a bullet goes through air, but with less resistance. If the event horizon is the same diameter as a golf ball, it will consume around 22,000 metric tons of matter before leaving the Earth. It will not have enough time to create a measurable accretion disk, so it would probably only release energy equivalent to a couple of large nuclear weapons. You might get a few major earthquake, volcanic eruptions, and tsunamis triggered by the tidal effects, but they will be localized.

[PTTG]

Originally Posted by AlexanderHowl

A relativistic black hole will pass through the Earth like a bullet goes through air, but with less resistance. If the event horizon is the same diameter as a golf ball, it will consume around 22,000 metric tons of matter before leaving the Earth. It will not have enough time to create a measurable accretion disk, so it would probably only release energy equivalent to a couple of large nuclear weapons. You might get a few major earthquake, volcanic eruptions, and tsunamis triggered by the tidal effects, but they will be localized.

It'll hardly be bad at all!

[sir_pudding]

Originally Posted by AlexanderHowl

A relativistic black hole will pass through the Earth like a bullet goes through air, but with less resistance. If the event horizon is the same diameter as a golf ball, it will consume around 22,000 metric tons of matter before leaving the Earth. It will not have enough time to create a measurable accretion disk, so it would probably only release energy equivalent to a couple of large nuclear weapons. You might get a few major earthquake, volcanic eruptions, and tsunamis triggered by the tidal effects, but they will be localized.

I suspect you are seriously underestimating the cascading effects of the atmospheric heating, crust melting, mantle deformation, and debris cloud that would result.

At any rate a 100 meter long, 1 mm in diameter, aerogel noodle falling at 9.8 m/s/s would do significantly less.

Edit: A black hole with a Schwartzchild radius of 1cm has a mass of 1.1 Earths, and if traveling at 70% of the speed of light, a kinetic energy of 2.4×10^41 or about 10^9 times the gravitational binding energy of the Earth. I am reasonably certain that would result in significantly more problems than than a few earthquakes.

[AlexanderHowl]

The object would pass through the Earth in 0.05s or less, so there is not enough time for major heating as the vast majority of the matter it would encounter would interact with its event horizon. The Earth might as well be vacuum to something with infinite density, so there would be very little interaction. At worst, you get a couple of localized disasters at the entry and exit points and a lot of confused scientists (the Tunguska Event anyone?).

[sir_pudding]

Originally Posted by AlexanderHowl

The object would pass through the Earth in 0.05s or less, so there is not enough time for major heating as the vast majority of the matter it would encounter would interact with its event horizon. The Earth might as well be vacuum to something with infinite density, so there would be very little interaction. At worst, you get a couple of localized disasters at the entry and exit points and a lot of confused scientists (the Tunguska Event anyone?).

Half a second of 10^9 times the gravitational binding energy of the Earth.

The atmosphere has a heat capacity of about 5.95×10^21 J/C, so in half a second it will heat up by about 2×10^19 C (which incidently is significantly hotter than Nitrogen plasma, so it isn't really an atmosphere at that point, more like an explosion).

[robkelk]

Originally Posted by sir_pudding

... I am reasonably certain that would result in significantly more problems than than a few earthquakes.

That depends on the earthquakes. As Randall Munroe pointed out on page 290 of his book what if?, "the Death Star caused a magnitude 15 earthquake on Alderaan."