Plan Nine From Inner Space: The Core

Steven Dutch, Natural and Applied Sciences, Universityof Wisconsin - Green Bay
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Hot Babe Scientist. Linus Pauling never looked like this. Hollywood is now capable of dealing with a woman scientist. Someday they will be capable of portraying a plain, middle-aged or overweight woman scientist.


Hunk Scientist. Linus Pauling never looked like this, either. Stephen Hawking may be a great heroic role model, but good looks sell tickets.


High Caloric-Intake Monster. Large animals eat a smaller fraction of their body weight each day than small ones, a manifestation of surface to volume ratio. Hollywood critters, on the other hand, eat like shrews.


Pompous Ass who Pays With His Life. The pig-headed boss or political figure who refuses for selfish reasons to listen to warnings and gets killed. Occasionally it really happens; the governor of Martinique refused to evacuate when Mont Pelee began erupting 1902, and died in the resulting catastrophe. So did 30,000 innocent people.


Superfluous Kids. Kids (generally repugnant) who serve no real dramatic purpose except to generate audience sympathy. I root for the monsters, especially when the kids do something stupid after they've been told not to.


Cookie Crumbs Have No Calories. And large objects (like asteroids) cease to exist once they're broken up.


No Other Scientists in the World. Apart from the two or threecharacters in the film, nobody else in the entire worldwide scientific communityis aware anything unusual is going on. Nobody else seems to be aware of the hugetidal waves, plagues of locusts and frogs, rain of blood, global slaughter offirst-born, etc.

The Core (HBS, Hunk, PAPWL, NOSW)

Rarely does a capsule summary of a film say as much as Roger Ebert's: Hedescribes the film as "sillier than it sounds" but only "a stepbelow Congo, Anaconda, Tomb Raider, and other guilty pleasures." Sillier than it sounds? A step below Anaconda?

Although I couldn't resist the cheap shot in the title of this page, Iactually enjoyed this film more than I thought, in large part because the filmdoesn't take itself too seriously. For example, when a scientist says it wouldtake ten years to make his earth-boring machine operational, a general asks whatit would take to do the job in three months. "Fifty billion dollars.""Will you take a check?"

Boston: 32 civilians suddenly drop dead in their tracks, all wearingpacemakers. London: flocks of pigeons become disoriented and slam into buildingsand people. A hot-shot geophysicist, Josh Keyes (Aaron Eckhart) suspects disturbances of the earth'smagnetic field and puts his graduate students to work searching for otheranomalies. Of course, nobody at Harvard or M.I.T. actually has instrumentsmonitoring the earth's magnetic field when the pacemaker owners are zapped.

The Space Shuttle Endeavor, returning from space, suddenly turns up far offcourse and headed for impact in Los Angeles. When the crew first sees theground, the Channel Islands are dead ahead, making me wonder why they didn't tryfor a water landing rather than endangering people on the ground. At the lastmoment, the hot shot female co-pilot, Major Beck Childs (Hilary Swank) comes up with a plan: landin the Los Angeles River, which is a concrete channel.

Our hot-shot geophysicist hands his theory that the earth's magnetic field isbreaking down over to Dr. Conrad Zimsky (Stanley Tucci), the World's Leading Geophysicist  who, it turns out, is already aware of a problem. He invitesKeyes toWashington, where they brief the military on the threat. The problem with makingsci-fi movies for audiences with the scientific literacy of doorknobs is thatall the expository material has to be at that level. Thus we get to see abriefing to the highest leadership of the military (all of whom certainly have graduatedegrees) that sounds like a third grade lesson plan dumbed down. The bottom lineis that the earth's core has stopped rotating, which in turn will lead to theloss of the earth's magnetic field and its radiation shielding ("themagnetic field is our friend," the brass is told). Within three months"we're back to the stone age" as all electronics are fried, within ayear, the human race is dead from radiation. Meanwhile, there will be superelectric storms and deadly bursts of microwave radiation.

Well, every million years or so the earth's magnetic field changes direction,which means that in the interim the field either disappears or at the very leastbecomes very chaotic, yet there are no correlations between magnetic fieldchanges and extinctions. If all electronics were to be fried, that would indeedplunge the world into chaos, but we could reconstruct the technology of 1940, or1900, easily enough, neither of which were exactly Stone Age. The magnetic fielddoes indeed divert charged particles, but most of them are funneled into theearth's polar regions, creating auroras and electromagnetic disturbances, butnot exactly bathing Iceland or Alaska in lethal radiation. And microwaves arenot affected at all by the earth's magnetic field.

The participants of the briefing emerge to see the night sky shimmering withstrange lights. "High-level static discharges," mutters Keyes, apparentlynever having been introduced to the aurora borealis during his geophysicstraining. Nor, apparently, are there any other scientists struck by the suddenonslaught of auroral activity at low latitudes. What are they all doing,studying to be on Weakest Link?

Hang Up Your Disbelief

If you're going to watch Star Trek, you have to accept that there are ways oftraveling faster than light. If you're going to watch The Core, you have toaccept that there is a way to travel to the earth's core. During the briefing, Zimskymuses that there might be a way to get there after all. Seems he has anex-colleague, Ed Brazzelton (Delroy Lindo: he's ex because Zimsky stole his research) living as a hermit in the Utahdesert and working on tunneling machines. I always wonder about hermitscientists. First of all, you have to buy groceries. Then you have to buy anabandoned military base, and even if you get it cheap, you have to pay propertytaxes on it. Then they always have huge amounts of exotic equipment. Where dothey get the money for this stuff? Does the National Science Foundation havesome kind of Hermit Scientist program?

Brazzleton has two key ingredients for a core-borer. First he has a seriouskick-butt laser array that bores holes in rock like soft butter. Second he has amiracle alloy whose full name is "37 syllables long" but which henicknames "unobtanium." This stuff actually gets stronger withincreasing temperature and pressure and, amazingly, also turns heat into energy.At this point there is no point in even attempting to complain about violatingthe Second Law of Thermodynamics.

Project Deep Earth

So Project Deep Earth gets under way. The crew consists of Keyes, Zimsky,Brazzleton and a French colleague of Keyes, Serge Leveque (Tchky Karyo). The pilots are the pilot and co-pilot of the crashed space shuttle, who wereexpecting to be cashiered but who were instead commended for theirresourcefulness and given command of this expedition. Rounding out the ensembleis Rat (D.J. Qualls), a world-class computer hacker who is given the task of keeping theimpending disaster secret by suppressing all chatter about it from the Internet.Either that or go to prison for hacking.This plan will work because nobody will talk about these events on the phone,see them on the news, or spread rumors word of mouth. And of course the Internetis totally free of conspiracy believers who might become suspicious if certaintypes of pages keep disappearing.

At critical moments, the hush-hush nature of what's going on is underlined bycloseups of folders marked "Secret." Sorry to disillusion anyone (notreally), butSecret is not all that impressive in the military. Routine military exercisesare typically classified Secret. Top Secret is where it's at, and reallyimportant stuff is classified at levels above Top Secret. By the way, the coversheets themselves are unclassified. Makes sense. If the cover sheets were classified, youcouldn't know you were in danger of violating security without actually doingit.

Major Childs is itching to be a commander, but the pilotCommander Iverson (Bruce Greenwood) tells her she's notready. She's too used to winning, he says, and you can't really lead until youknow what it's like to lose. So we know this guy is toast. I wonder why he evenpacked for the trip. He's so temporary the film doesn't even attempt to give hima personality.


The ship is the ultimate subway train, built in six modules connectedtogether. It can flex, but more importantly, damaged modules can be jettisoned.I wondered how they knew that only the rearmost module might take damage, andwhat might happen if, oh, the second module had a hull breach. The ship islaunched (dropped) into the Marianas Trench, a site picked by Zimsky for havingthin crust. In a nice scene, whales, attracted by the ship's sonic emissions,follow it down. But alas, the Marianas Trench is seismically active, and anundersea earthquake creates tension before the ship's lasers fire in the nick oftime and the ship starts melting its way through the mantle.

If you want to get into the earth this way, seems to me you'd want to go inwhere rocks were already hot and soft. Say, a rising mantle plume like Hawaii.Or maybe a mid-ocean ridge. But not a trench, where you have cool rigid crustand upper mantle to penetrate. Oh well, guess that's why I'm not the World'sLeading Geophysicist.

The trip down is at a nice leisurely 60 miles an hour. I wondered how theywould show any outside views, but we learn enough about the ship's imagingsystems to make it at least semi-believable. But there are other things not sobelievable. For one thing, they have communications. The movie never evenattempts to explain this. Extremely low frequency (ELF) radiation can penetratethe deep earth, but it's slow as molasses. Submarines that use it to communicatecan transmit and receive about a character a minute. Typically they use shortcoded messages as signals to surface so they can transmit conventionally. So howthe ship gets voice and even video to and from the surface is a deep mystery.

A Killer Electric Bill

Worst of all is the energy problem. It takes about 400,000 joules to melt akilogram of rock. The ship is about five meters in diameter, so let's say it hasa cross-section of 20 square meters. It has to get through the mantle, a trip ofabout 3,000 kilometers, meaning a total of 60,000,000 cubic meters of rock tomelt. Mantle rocks weigh about 3300 kilograms per cubic meter, meaning the shiphas to melt 200 billion kilograms of rock. So it will take 8x1016 joules to meltto the core. You may not be familiar with a joule (lifting a pound one footrequires a bit more than one joule) but you know what a watt is. A watt is onejoule per second. It will take a bit over 24 hours to reach the core, or closeto 100,000 seconds, so our total emission of 8x1016 joules in 100,000 secondsworks out to 8x1011 or 800 billion watts. That's one heck of a laser system. Nowheavy duty house wiring for a stove or heater running 1000 watts has to bepretty thick. Let's assume you can carry 1000 watts for every square millimeterof wire. That means 800 billion watts needs 800 million square millimeters ofwire or about 800 square meters, or about 40 times the cross-section of theship. I wonder who inspected the wiring.

Could the reactor handle the power demands? Well, if we could convert mattertotally into energy, we could get that 8x1016 joules out of less than a kilogramof matter. This is Einstein's famous E = mc2, and once you get over beingfreaked out by the name Einstein, it's middle school math. The quantity m is mass inkilograms, c is speed of light in meters per second (3x108 meters per second)and E is in joules. On the other hand, nuclear reactions only convert a tinyamount of matter into energy. The fact that a typical commercial nuclear powerplant is in the few hundred megawatt range doesn't inspire confidence. Akilogram of nuclear fuel can yield about 8x1012 joules of energy, so we onlyneed about 100,000 kilograms of nuclear fuel, or about 100 tons. Then there'sthe shielding, the coolant, the power generators, etc, as well as wires with 800square meters of cross section to carry the power.

One other point to put the energy demands in perspective. 800 billion joules(one second's worth of energy output) is about 1/6 of a kiloton. The reactor iscranking out the equivalent of a Hiroshima explosion every two minutes. Wonderwhat they're using for control rods.

Wouldn't it get easier to melt rock as we go down and it gets hotter? Rocksdeep in the mantle are far hotter than their surface melting temperature, butthey are still solid. Liquids take up more space than solids, and pressure tendsto inhibit melting. Ice is an exception precisely because it takes up more spacein the solid form than the liquid form, and pressure favors the melting of ice.But to melt deep mantle rocks, you'd need to supply enough energy to get theatoms to break apart and overcome millions of atmospheres of pressure. So bottomline, probably not enough to make the energy demands even remotely plausible.

Oh, one more thing. These calculations have been just for getting tothe core. Double everything to get back.

Staying Cool

Speaking of heat, this ship has one humungous cooling issue, which is solved,we hear repeatedly, by "liquid nitrogen." I don't even want to thinkhow much liquid nitrogen it would take to stave off temperatures of 5000Centigrade. Also, consider this. If the ship's power system is 99 per centefficient, those 800 billion watts that it's cranking out will radiate 8 billionwatts of waste heat inside the ship. If you think I overestimated thewire needs, consider that the thinner the wire, the more resistance and the moreheat.

Energy is proportional to temperature raised to the fourth power, wheretemperature is measured in degrees above absolute zero (the Kelvin scale). Thecore, at 5000 degrees, is about 20 times as hot as the earth's surface (notcounting atmospheric effects) so the energy striking the ship is about 160,000times (20 to the fourth power) what sunlight supplies to the earth. The sunsupplies 1400 joules per square meter per second (or 1400 watts per squaremeter) to the earth, so the core is supplying 160,000 times that to the ship, orabout 2.25 billion watts per square meter. If the ship is five meters indiameter and 50 meters long, it has about 800 square meters of surface area andhas to fend off 1.8 trillion watts of heat. This is in addition tothe 800 billion watts the ship is using to melt rock. We need apretty honkin' big air conditioner.

Things in the Mantle

700 miles down, the movie encounters the biggest plot hole: a hole. A cavity."Impossible," cry the geophysicists, and I agree wholeheartedly. Maybeit has a "cobalt shell," they theorize. Cobalt, neutronium, pixiedust, ain't gonna happen. Not nohow, not no way. Pressures at depths beyond a fewkilometers deep would crush cavities out of existence. Nevertheless, the shipplummets into the cavity, which turns out to be lined with stupendous crystals.Perfect hexagonal prisms with pyramids, the only kind of crystal special effectspeople have ever seen. "Amethyst," says one of the geophysicists.Amethyst is a form of quartz, and we're at depths where quartz is compressedinto denser forms, plus you're not likely to find quartz in the silica-poormantle. Then again, you're not likely to find huge cavities kilometers across inthe deep mantle either, so why get upset about the mineralogy?

Alas, one of the crystals has jammed the laser array and has to be cut. Thecrew ventures outside, relieved to discover the suits can withstand thepressure. At least the writers realized there would be pressure - I halfexpected them to take their helmets off and start breathing oxygen. The ship,however, has punched a hole in the shell around the cavity, and chunks of rockand a river of lava start falling in. A chunk of rock obligingly slams into CommanderIverson's head, fatally injuring him before he even more fatally falls intothe lava. So Major Childs gets her shot at command.

Just before the core, the ship encounters something it can't penetrate:diamonds hundreds of meters across. Oddly enough, this might just be possible,though I rather doubt any accumulations of carbon in the mantle ever get thatbig. Childs tries to avoid one but hits it a glancing blow, Titanic-style.The rear section takes a hull breach. Keyes and Leveque are back therecalibrating the timers for the nukes, and Leveque is trapped while retrievingone of the timers. Childs proves she can Make The Tough Call by sealing off andjettisoning the section despite Keyes' impassioned screams to open the door.

Into the Core

The ship drives on and plunges into the core. Then it rapidly accelerates.Good news? The trip will go faster? No, bad news. They have overestimated thedensity of the core. It's less dense than they expected so the ship sinksfaster. This unfortunately means the nuclear blast won't be able to get the corespinning. Zimsky, who has been a pompous ass from the git-go, begins demandingthat they abort the mission and go home.

Now do they mean density, how much the core weighs per unit volume, or dothey mean viscosity, how much resistance the core puts up against flow? Thereare a lot of things we don't know about the core, but density is not one ofthem. First of all, we know the mass of the earth and we know its moment ofinertia, a quantity related to the earth's rotation. These two quantitiesrequire the mass within the earth to be distributed in a certain way. As a crosscheck, the velocities of seismic waves also depend on density. So how densityvaries in the earth is known to pretty good precision. Other things, liketemperature or viscosity, are not known nearly so precisely. In the 1980's studies ofhigh-pressure materials indicated the core was a couple of thousand degreeshotter than previously believed. Besides, we're to believe this mission waslaunched at a cost of $50 billion and nobody ever ran different scenarios to seewhat might happen if our estimates were off?

Gravity does interesting things deep in the earth. The gravitational pull ofa surrounding external shell is zero, so in a uniform earth the pull of gravitywould decrease linearly as you approached the center. In the real earth, as youdive deeper you approach the dense core. Gravity holds remarkably steadythroughout the mantle, actually increasing a few per cent near the core-mantleboundary, then starts to drop fairly linearly. So at the inner core boundary theship would be at less than half a g of gravity, something not considered in themovie.

The crew comes up with an alternate plan. Detonate the nukes sequentially sothe shock waves reinforce each other. Unfortunately the nukes were made to bedetonated as a single unit and don't have individual protective shells. Okay, sowe put each nuke in a module of the ship and disconnect the modules.Unfortunately, the ship wasn't designed to disconnect intact modules, and thehydraulic control is in a part of the ship that will be seriously lethal oncethe control is disabled. Brazzleton volunteers, and Zimsky makes his peace with him justbefore the end.

Fun With Atoms

At the last moment, Keyes and Zimsky realize they have forgotten a key coreparameter in their computer models and the last bomb in the series is too small.Zimsky gets pinned behind a nuke in a section about to be jettisoned, but Keyes pullsthe fuel rods from the ship's reactor and places them next to the final bomb(ignoring the probably lethal radiation exposure from the reactor fuel) to give it a bit more oomph.

Frankly, I like this. The more messed up people's conception of nuclearweapons is, the less likely it is that someone will actually be able to buildone at home and the safer we all will be. The Core, by that standard, comesclose to deserving a Nobel Peace Prize. Without in any way providing any usefulinformation, there are two sizable bloopers in the film's nuclear scenario.(Everything in the next two paragraphs is available in open U.S. Governmentliterature and has been for decades.)

First, in order to set off a nuclear weapon, you have to get uranium orplutonium into a critical mass, a mass big enough to allow a chain reaction tofission a large part of the uranium or plutonium atoms. The problem is that bythe time the reaction is well along, you have a nuclear explosion trying to blowthe rest of the fissionable material apart. You have to get the fissionablematerial together and keep it together for a few microseconds. Just putting abit more plutonium next to the bomb won't do anything except make the fallout abit more radioactive.

Second, there's a reason why the world's nuclear arsenals top out at around20, rather than 200, megatons. Anything over roughly a hundred kilotons requiresfusion. The bomb gets its energy from fusing light hydrogen atoms. Guess that'swhy they call them "hydrogen bombs," right? Problem: in order to getthe fusion started, you need temperatures and pressures normally found in theinterior of the sun. Or in the middle of a nuclear explosion. So hydrogen bombswork by setting off a nuclear explosion which in turn triggers the fusion ofhydrogen. So increasing the power of the initial nuclear explosion by addingmore plutonium won't really have much effect. You might think that just addingmore hydrogen would allow you to get as large an explosion as you like, but theproblem is there's an atomic bomb going off right next door. Only a certainamount of hydrogen can undergo fusion before the bomb gets blown to smithereens,and the practical upper limit seems to be 20 megatons or so. The Soviet Unionclaimed to have tested a 50-megaton bomb in the 1960's, but there is good reasonto doubt if a functional 200-megaton bomb is possible, even in theory.


As if to underscore the seriousness of the situation, a hole develops in themagnetic field over California, allowing those nasty microwaves to get through.A beam of microwaves hits the ocean full force, boiling water and killing thepoor fishies, then the beam sweeps in over the Golden Gate Bridge. A haplessmotorist with his arm out the window finds it instantly severely burned, butworse is to come. The microwaves heat the pavement, melting asphalt and tires.Electric currents induced in the bridge create huge electric arcs, then thecables, heated to incandescence, fail, and the span drops into the water. Thebeam sweeps on over San Francisco, leaving much of the city in flames. It's adramatic illustration of what might happen if any of this were actuallyphysically possible.

Now there are proposals to put huge solar electric generators in orbit andbeam the power to earth as microwaves, and if the movie were about a solargenerator whose microwave beam drifted off target, this would be a great scene.But the sun generates only a small amount of microwaves (at radio wavelengths,the earth far outshines the sun) and they pass through the earth's magneticfield and atmosphere unimpeded all the time.

Nevertheless, the commanding general (Richard Jenkins) decides the time has come to try another plan.Unconvinced that the crew can get the core spinning with their nuclearexplosives, he orders Project Destiny activated. Turns out Zimsky was in onDestiny, a program for remote triggering of earthquakes, and there are darkhints that Destiny may have caused the core problem in the first place. Destiny stands for DeepEarth Seismic Triggering INItiation. The General orders the ship to return, butthe crew refuses, whereupon he orders Destiny activated anyway, even though itwill destroy the ship.

Say what? This ship is taking millions of atmospheres of pressure andtemperatures approaching those on the surface of the sun, and is about to take shockwaves from the largest explosions ever generated, and Destiny will destroy it?How? The hull gets stronger under pressure. Nevertheless, the crew is concernedthat Destiny will set off chaotic instabilities in the core. Rat the hacker,whose function up till now has mostly been to watch global disaster reports onhis monitor, sends a coded message to the crew, who advise him to stall Destiny.Apparently it has never occurred to the General that Rat might try anythingunauthorized, but Rat begins hacking into Project Destiny, and for some reasonhis searches hit despite the fact that the acronym is actually DESTINI. Destiny(or DESTINI) uses a lot of power, and with the West Coast power grid out ittakes most of the power east of the Rockies to make it work. This is a topsecret program to generate devastating earthquakes untraceable by our enemies,who will never figure out there's a connection between their earthquake and muchof North America having a brownout immediately beforehand. In the nick of time,Rat shuts down Destiny.

Happy Ending

The nukes go off, the plan works, the core starts spinning again. Jubilationin Mission Control. Unfortunately the ship, with its reactor fuel gone, is deadin the water, or molten iron. Aha, exults Keyes, unobtanium converts heat intoenergy! They hook the wiring to the hull and power up. But they don't haveenough for lasers. Instead, they follow rising magma streams upward, eventuallycoming out of a submarine volcano off Hawaii. Now they really are dead in thewater with no way to communicate. The Navy has a rough idea where they are butall they can pick up on the sonar are whales. Rat realizes the whales areresponding to signals from the ship and the two survivors (Keyes and Childs, incase you've been keeping count) are rescued.

The movie ends with Rat blowing the lid off the Government's attempt to keepthe project secret.


The August 2003 issue of Scientific American (p. 24) describes asemi-serious attempt to design a probe capable of reaching the earth's core.Serious, in that the scientists seriously attempt to come up with a physicallypossible way to do it, semi in the sense that the physical demands are enormousand some of the technology is still out of reach. The plan involves meltingseveral million tons of iron, which would sink down through the mantle becauseof its high density. That part we can do. 

It's designing a probe to survive the temperatures and pressures that's thehard part. Diamond could probably stand it, but what would you use forelectronics? Solid state electronics depend on keeping electrons and impurityatoms in semiconductors in precise configurations, and heat is deadly. Anyonewho's ever fried a motherboard because they blocked the heat vents on a computercan testify to that. Solid state electronics can barely tolerate the boilingpoint of water, let alone the melting point of iron. 

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