Image: Scene from "The Core"
Bolts of super-lightning zap city streets in a scene from "The Core." In reality, the effects of a disruption in Earth's magnetic field wouldn't be that severe, most scientists say. But questions remain.
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msnbc.com

As if we didn’t have enough to worry about, a new movie called “The Core” adds yet another potential doomsday to the list: a disruption in Earth’s magnetic field that sparks a global cataclysm. It may seem like typical disaster-film fare, but the premise actually touches upon real-life scientific mysteries: What keeps the magnetic field going, and what happens when it flips?

“The Core,” opening nationwide Friday, represents Hollywood’s most ambitious attempt in decades to build a plot around a journey to Earth’s core. Unlike “Journey to the Center of the Earth,” this trip is a rocky ride for the whole planet: When the natural dynamo at the core fails and the magnetic field falters, all of humanity is left open to cosmic rays and super-duper electrical storms. Rome’s Colosseum blows apart. The Golden Gate Bridge collapses. And that’s just the start: Unless something is done, the sun will blast Earth like a blowtorch melting a bonbon.

Responding to the crisis, an intrepid group of scientists ride a laser-equipped craft named Virgil into the inferno to jump-start the core with a well-placed nuclear device. In the process, the “terranauts” have to deal with the nefarious government program that endangered Earth’s dynamo in the first place.

Scientists may tut-tut over the outrageous premise. No person or device could possibly survive the crushing pressures that exist 1,700 miles beneath Earth’s surface. And the magnetic field doesn’t have all that much to do with the kind of cosmic blast shown in the movie. But strangely enough, the movie is coming out just after the publication of a controversial paper claiming that our planet’s internal dynamo could start running down in as little as 100 years.

That plays right into the hands of director Jon Amiel and the publicity campaign for “The Core.”

“We tried to really put the science back into science fiction, to make the science fun,” Amiel told MSNBC.com. In fact, in the production notes he calls his movie a work of “science faction,” with “a good dollop of science, a considerable amount of fact and a wee bit of fiction.”

Many geophysicists would take issue, saying “The Core” contains just a wee bit of science buried in a huge dollop of fiction. But J. Marvin Herndon, the maverick behind the dying-dynamo theory, salutes Amiel’s style.

“Jon has a good, healthy attitude toward science,” Herndon, who became acquainted with Amiel during the film’s production. “He thinks new ideas ought to be debated and discussed, and I think that’s good. I wish more scientists had that attitude.”

Nuclear planet
Herndon has worked for almost a quarter-century on his “nuclear planet” theory, which proposed the existence of a 5-mile-wide (8-kilometer-wide) ball of uranium at Earth’s very center. This natural nuclear reactor would transfer heat from the planet’s solid inner core to the liquid outer core, powering a flow of molten metal that acts like an electromagnetic dynamo and sustains Earth’s magnetic field.

His latest study, published in the March 18 issue of the Proceedings of the National Academy of Science, is based on a computer simulation predicting how such a reactor would behave over billions of years. The simulation, conducted by Oak Ridge National Laboratory, yielded data on the levels of different helium isotopes that should be given off by such a reactor. Those hypothetical levels closely matched the actual levels found in rock being thrust up from Earth’s interior.

The simulation also predicted that the reactor’s uranium fuel should run out about 4.5 billion to 5.5 billion years after its startup. That could be bad news, since scientists believe that Earth was formed about 4.5 billion years ago. The results led Herndon to conclude that Earth’s core reactor has somewhere between 100 years and 1 billion years left.

If you accept Herndon’s theory, it would then just be a matter of time before Earth’s magnetic field dissipates.

“Life on Earth will never be the same,” he said.

How bad could it be, and could we do anything about it? This is where Herndon parts ways with “The Core.”

“When this happens for us, we won’t be able to send terranauts to fix it, even if we had the technology,” he told MSNBC.com. “I don’t think it will be the end of life as we know it. We’ll just have to learn to live with the solar wind.”

Reality check
Only the most dire doomsayer would claim that a fizzling magnetic field would produce the catastrophic effects shown in “The Core.”

“Well, we don’t exactly know what’s the truth,” Amiel admitted. “It could be nothing more in the first instance than people getting carcinomas, in fact similar to those which people have had due to the hole in the ozone layer.”

Scientists point out that it’s actually the atmosphere, rather than the magnetic field per se, that shields Earth from cosmic rays. Moreover, an analysis of magnetized rock layers indicates that the magnetic field has reversed itself eight times just in the past 2.5 million years or so, leaving behind no evidence of global catastrophe. So the Colosseum and the Golden Gate Bridge are most likely safe, even if Earth’s magnetism goes temporarily haywire.

What the magnetic field does protect Earth from is the solar wind, a million-mile-an-hour stream of electrically charged particles coming from the sun. Even today, the world’s power grids, orbiting satellites and even spacewalkers are occasionally vulnerable to especially strong solar outbursts. The exposure is particularly troublesome in an area called the South Atlantic Anomaly. A fading magnetic field would cause even more trouble for today’s high-tech world.

Scientific debates
It’s about at this point that the scientific debates kick in at full throttle. Some researchers contend that the magnetic field is decaying to such an extent that it could disappear or reverse in the next couple of millennia. Others say concerns about the decay have been overblown.

Meanwhile, Herndon’s theories on the “nuclear planet” are far from being widely accepted, even though they’ve been propounded in peer-reviewed journals as well as mass-market magazines. In fact, he says his work has been “systematically ignored” by much of the scientific community.

“I’ve never been able to get funding for my research in 24 years,” he said.

He currently earns his living as a consultant to the defense industry, principally on mineral technology. “I have been in the antique business at some time in the past — whatever it takes to keep the wolf from the door,” he said.

In contrast to Herndon’s claims, the leading theories hold that the magnetic field was set when Earth formed, and that it’s sustained by the slow transfer of heat from Earth’s cooling core. According to these theories, radioactive decay may be a factor in the planet’s heat balance, but not the crucial factor.

If these theories are correct, the spinning core is a consequence of Earth’s magnetic field, and not the cause. That line of reasoning led Gary Glatzmaier, a geophysicist at the University of California at Santa Cruz, to tell Popular Science magazine that the scientific reasoning behind “The Core” was “almost completely backward.”

Such comments rub Herndon the wrong way. He says those other researchers haven’t considered that Earth’s composition might be similar to that of a particular kind of material called an enstatite chondrite — which would allow uranium to coalesce at the planet’s core.

But do moviegoers really have to delve that deeply into the geophysical debate to get into “The Core”? Probably not. For all his talk about “science faction,” Amiel conceded that the main aim of the science in “The Core” is to enhance the fiction.

“In every good science-fiction movie, you get a couple of ‘gimmes,’” the director observed. “In ‘Fantastic Voyage,’ the gimme is that the technology exists to minimize the crew to a size that would fit inside a human body. Once you take that premise, provided you follow it through, you can bring the audience along with you. ... What is factually accurate and what is believable can be two different things.”

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