What scientists love and lament when Hollywood journeys to Earth's core

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The Core released to audiences 20 years ago. Ever since, audiences have bemoaned, laughed at and loved the loose use of geological science in the film. PictureLux/The Hollywood Archive/Alamy hide caption

toggle caption PictureLux/The Hollywood Archive/Alamy

The Core released to audiences 20 years ago. Ever since, audiences have bemoaned, laughed at and loved the loose use of geological science in the film.

PictureLux/The Hollywood Archive/Alamy

It's been 20 years since 'The Core' first graced the box offices. That means 20 years for scientists to puzzle over the interesting science Hollywood used in the delightfully ridiculous disaster movie.

Today, Short Wave Scientist in Residence Regina G. Barber jumps into that fray with former Western Washington University colleague and geophysicist Jackie Caplan-Auerbach. They discuss what the film gets right and what's just fun.

Earth grinds to a halt

In the movie, Earth's core stopped spinning, disrupting the planet's magnetic field. There's global chaos as birds fall from the sky. So, a ragtag team of scientists and military officials must travel to the center of Earth to fix it — and restart the rotation of Earth! (Collectively, the group is known as "terranauts," a clever combination of the Latin terra, meaning "land," and the Greek nautēs, meaning "sailor.")

When Jackie shows this movie to her students each year during finals week, she explains why the planet's magnetic fields going haywire is not great, "Earth's magnetic field does protect us from what we call the solar wind, which are charged particles that come from the sun."

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But the movie asserts that a ripple effect of stopping the core and messing with the planet's magnetic fields is the planet being subjected to harmful microwave radiation. An idea to which Jackie is quick to respond, "It is not, as the movie suggests, that we're all going to be fried by the sun's microwave radiation. ... Microwaves are not affected by magnetic fields."

Still, our scientific and military heroes must journey on, to restore the balance of the world and eliminate all problems, realistic or not.

A nuke to save the day?

A major plot point of the film is the dramatic way the Earth's core must be reset so that it can resume spinning. "As with all bad science movies, this is accomplished via nukes," Jackie laughs. But is that a real solution?

To this question, Jackie has a simple answer: "Heck no! No, no. You can't nuke the core." That's because the whole premise that the spinning core is creating Earth's magnetic field is flawed.

The movie gets right that Earth's magnetic field is generated in the planet's core, "But the suggestion is that what causes the field is the fact that our inner core is rotating, and that's not really correct," Jackie points out. "The thing that really causes the magnetic field is basically the fluid dynamics of Earth's liquid outer core."

Getting to the heart of the matter

So okay, pointless mission aside, how does one even get to the center of the Earth? Isn't there too much pressure and high temperatures?

Yes. But the movie finds a loophole to this problem through the use of a make-believe element called "unobtanium." This metal is what the ship used by the terranauts is made out of.

Thanks to unobtanium, our terranauts breeze through Earth's first layer, the crust, like they are diving into a swimming pool. It takes them minutes to get through to the next layer, Earth's mantle.

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Let's stop here for a fact-check because, according to Jackie, they would've had to stop long before this. "We've never so much as drilled to the mantle. We've never seen it in its native environment. So when we talk about, 'Could we get to the core?' We can't even get through the crust," she laughs.

Jackie uses this inaccuracy – one of her favorites – as a learning opportunity for her students.

When the film's heroes find themselves in Earth's empty mantle, disembark from the ship and are not crushed, she explains the scientific impossibility of the scenario. Simply put, "The pressure at that point would be astronomical being enormous, enormous pressures. There is no way you would have a big, open, empty space at those kinds of pressures if you had a big open space." She says that the only way for the terranauts not to be completely crushed by the weight over over 700 miles of Earth on top of them, something would have to be pushing outward. Such a thing does not exist, and yet, she notes, "They're out there walking around like it's atmospheric pressure."

The other big lesson across all of the debunked science? There can be joy in the unscientific – and a loving jab in the name of explanatory science never hurt anybody.

We're excited to watch 'The Core' again and again, armed with science.

This edition of our periodic 'movie club' series, where we separate fact from fiction, was highly requested by you, our audience. If you want us to do the same for another movie you love, write us! We're at shortwave@npr.org.

Listen to Short Wave on Spotify, Apple Podcasts and Google Podcasts.

This episode was produced by Liz Metzger. It was edited by Rebecca Ramirez and fact-checked by Will Chase. Josh Newell was the audio engineer.