The Black Hole That Ate My Earth


News organizations excitedly announced last week that CERN's Large Hadron Collider (LHC) is back in business and reaching record-breaking particle collisions that take physicists to within seconds of the Big Bang.

The news made it above the fold on the front page of the March 31 New York Times — a rarity for hard science stories. The Times photo could only showed a lot of computer screens at CERN. Only our imaginations are left to try and visualize the quantum universe.

Even without pretty pictures, the LHC has become the Hubble Space Telescope of the subatomic world. That's no small task considering the machine has a terrible name. I'd prefer Super-Duper Atom Smasher. You could call it the Big Bang Machine, though the collider is many orders of magnitude weaker than the energies generated at the instant of the Big Bang.

You'd be hard pressed to find anyone on the street who could tell you what the sought after Higgs Boson is, or why it is so important. Therefore, what has given the LHC popular attention is the idea that it might make a black hole -– which to the layperson is somewhat definable and somewhat imaginable purely by its name. This has also given the LHC the nickname "Doomsday Machine" in some Internet chatter. The news media has gone nuts on this idea, and lawsuits have even been filed to stop the powerful facility from bringing a feared techno-Apocalypse.

I've joked that the LHC may be the answer to the Fermi paradox; we can't find any evidence of extraterrestrial civilizations because they all wind up building LHC’s that suck their planet down a black hole.

In reporting on the LHC's rebirth, CNN ran an outrageous doomsday video graphic it found on YouTube that shows a rogue black hole stripping down Earth like peeling an orange.

Physicists have assured us that any homemade mini-black hole that would quickly lose mass and evaporate before it could swallow anything in the LHC lab. What's more, high-energy cosmic rays (some coming from black holes, ironically) continually strike Earth's atmosphere with energies many orders of magnitude larger than what the LHC can generate. And we haven’t seen the radiation signature from a mini-black hole yet. (The Pierre Auger Observatory in Argentina is monitoring a wide swath of sky for cosmic ray events in the upper atmosphere.) Nor have we ever witnessed an astronomical body being swallowed by a mini-black hole.

But one astrophysicist told me that if you consider the spooky predictions from quantum physics, there is always an infinitesimally small chance an LHC interaction could make a black hole big enough to hang around for a while. The great British astrophysicist Sir Martin Rees has been equally cautionary, "It isn't good enough to make a slapdash estimate of even the tiniest risk of destroying the world," he said. Other physicists insist the chances are absolutely zero, zilch, no way, no how!

What's also often overlooked is that if a black hole were made, the speed of the impact would send it flying out of the solar system at a significant fraction the speed of light (unless we were really unlucky and it fell into the sun!).Only a perfectly balanced head-on collision between particles would yield a black hole with no escape velocity, where it could just sit around and start eating up things.

Nevertheless, just for fun and for all you 2012 Mayan calendar and Nostradamus doomsday soothsayers, what would happen if everything that's been theorized was wrong, and the LHC went haywire and made a permanent black hole?

To a large extent it's really anybody's guess, nature doesn’t do such experiments. But a few cautious extrapolations can be made from what little we do know about astronomical black holes.

The LHC black hole would start out with an event horizon so small, you would need a microscope to see it if the hole were massive enough. The tidal radius — where objects would be stretched and ripped to shreds — would not even extend beyond the LHC.

The black hole would sink through the floor toward the center of Earth. It would burrow through the mantle like a knife through butter on the 20-minute plunge to the core.

The black hole would be going fast enough, about 8,000 mph, to slice through the core and ascend to the opposite side of Earth, perhaps reaching the surface under the southwestern Pacific Ocean near New Zealand.

But the drag on the hole from accreting mass all along the way might slow it down. The black hole would oscillate back and fourth through the core. The black hole should eventually settle at Earth's center. The tidal radius would still extend for just a few miles from the black hole, but it would grow in extent too as the black hole swallowed up Earth's innards.

At some point presumably Earth's magnetic field would be disrupted because there is no longer a dynamo effect-taking place. This, perhaps aside from anomalous seismic waves, would give anxious surface dwellers some hint of what’s happening way down under.

Assuming the black hole is spinning it would form an accretion disk. Engorged with gobbled up mass from Earth's interior, the black hole would form a pair of relativistic jets. Call it the weed whacker from Hell. Observations of active galactic nuclei show that jets are not always symmetrical. If this were the case a single jet would propel a min-black hole around Earth's interior like a rocket motor.

Depending on the accretion rate of the black hole, it might take as long as several billion years to actually devour Earth.

When Earth was completely swallowed the event horizon would be only the size of a ping-pong ball. The tidal radius would extend about 20 miles out. The moon would continue to obediently orbit Earth, dynamically oblivious to the fact Earth has been, er, mini-sized.

Though this scenario would make a good cheesy TV sci-fi drama, in reality theorists say this kind of particle physics screw-up is as unlikely as creating a giant Schrodinger's cat that eats the Earth like a scene out of a Monty Python TV show.

But in the quantum world, never say never.

Black hole illustration credit: Don Dixon

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