ratbastid

Not right out of the chute, perhaps, but....
EEK!! MAN-MADE MICRO BLACK HOLE!

CERN's quest for the God Particle leads to their building the Large Hadron Collider inside which micro- and macro-physical forces unseen since the dawn of the universe are toyed with. One day the right muon smacks into the right gluon and BAM, micro black hole.

The singularity is, like any black hole, infinitely small. But it's also SMALL--its mass is that of the two subatomic particles that created it. So it's not the massiveness that makes it a black hole like in cosmological black holes, it's the density.

Our micro black hole has two things going against it. The first is that gravity is a function of mass and distance. Since the mass is so small, its gravitational field is very weak. So at first, only the particles that are vanishingly close to the microscopic event horizon (it has one, as nature abhors a naked singularity) are sucked in.

The second is that it's now emitting Hawking radiation. This is the safety valve built into the LHC (and unlike other gross speculations, rank assertions, and wild-ass guesses I'm making here, this paragraph is 100% true). Hawking radiation is emitted by black holes of any size, and since it causes the black hole to lose mass, it theoretically should have any micro black holes evaporate nearly as soon as they're created. This is what CERN says will keep us safe from this scenario.

Unfortunately, our little friend is created right in the stream of the Collider's particle fountain--so more and more mass is pumped into it. Within a few fractions-of-a-second, it's eaten all the particles in the Collider ring, and now has measurable mass. Still microscopic, but measurable. Enough to overcome both the minuscule range of its gravitational field and the evaporating effect of its Hawking emissions.

At this point, the magnetic containment of the ring can no longer direct it. A stream of individual particles, yes, but all the particles clumped together and emitting both Hawking radiation and a strong monopolar magnetic field, no. It begins to drop, and as it contacts the bottom of the ring, it eats whatever material is in its immediate path. It drops right through the ring, the floor of the tunnel, and falls straight through to the center of the earth leaving a charred circle surrounding a microscopic pinprick of a hole.

Now, here's where things get interesting. This thing was the product of collision between two particles of different masses. So it retained some linear velocity inside the Collider ring. Therefore its drop through the earth isn't at a 90-degree angle to the surface. It's elliptical. It doesn't tag the center of the earth. It accelerates PAST the center of the earth--eating as it goes--then decelerates as it approaches the surface on the other side.

Now, it won't quite reach the surface. It's eating the whole way, and so has encountered minimal friction to slow it on its journey, and it has so little mass that Earth's gravity has little effect on it. But the LHC is an average of 100 meters underground, so it will only carry enough velocity to reach that depth inside the Earth before gravity finally manages to overcome its velocity and pulls it back. But it's retained almost all of its lateral momentum, and will curve back and fall in a parabola back toward the center of the earth.

It will trace a lovely spirograph pattern as it goes, eating ever-growing, arcing paths out of the deep earth. You could say that it's in orbit around the Earth's center-of-mass; an orbit that will never have it climb high enough to exit the surface.

As it travels, it grows. So the tunnel it's cutting gets bigger and bigger, and the effects of the Earth's gravity on it get stronger and stronger. Its growth will be exponential--it'll only consume microscopic amounts at first, and that will be how it is for almost all of its life (or, I should say, all of our duration of being able to observe it). But eventually a time will come when its event horizon is the size of a golf ball, and it's eating a golf-ball sized channel through the earth with every pass, then the size of a baseball, eating a baseball-sized channel, then of a basketball, eating a basketball-sized channel, until it's the size of a car, then a house. And as it grows, Earth's gravity will exert a stronger pull on it--from ALL directions, not just from the center-of-mass. This will decay its orbit and cause it to reach ever shallower apogees on each orbit.

Before long (maybe 50 years?) its orbit has decayed to the point that it has hollowed out basically the entire center of the earth. All the matter that the weight of the earth is resting on is consumed and infinitely compressed inside this black hole, leaving a gaping void.

The tectonic implications of this are very serious indeed--earthquakes on an unprecedented scale for both intensity, frequency, and duration. Eventually the planet itself will break down and collapse into itself.

WHAT TO DO ABOUT IT

The most obvious thing is to invent space travel. Mars is our nearest safe haven--the Moon isn't safe from an Earth-sized black hole. Once this is showing effects, it's way too late; start working on that Mars rocket right now.

On the other hand, the black hole could probably be detected with a sufficiently sensitive seismological study from many points around the globe. If you could detect it and locate it at several points in time, you could predict where it will be several orbits from now, and could erect a magnetic tunneling system of sufficient strength to capture it. You'd need a massive magnetic containment field to hold it, and even then, you've got the tiger by the tail and you can't let go. If you dropped it, it would fall straight to the center of the earth and game over. You could put it in a rocket and fling it into space, but that's like the ultimate in being irresponsible with your trash.

Sources: Singularity, Bill DeSmet, Hyperion and The Fall of Hyperion, Dan Simmons

Singularity Spoiler: Whatever you do once you've got it captured, you don't want to use it to time travel to 1921 to prevent the assassination of Lenin, because paradox won't let you. But that's, frankly, a lousy way to end the story.