We meet Geophysicist Dr. Josh Keyes (Aaron Eckhart) as he's demonstrating how sound travels at different speeds through various types of rock. The scene plays as though it came from the memory of a ninth grade physical science student who mostly slept through class. It has bits and pieces of scientific facts blended with pure concoction arranged in a dream-like manner

We see an image of an oscilloscope with squiggly lines from a microphone picking up Keyes voice. Keyes correctly explains that when sound travels into higher density material its wavelength increases. He then throws in some pure nonsense about it also losing frequency. He points a trumpet at a slab of rock and proceeds to play random off-key notes supposedly to demonstrate some property of the rock.

This type of demo can show a representation of the sound waves produced by musical instruments. However, the instrument has to be played with a single continuous note. In such a demo, the oscilloscope displays sound intensity versus time. To calculate the speed of sound we would need distance versus time data. We're at a loss to explain what Keyes is really trying to do but are forced to give him the benefit of the doubt since he's snatched from class by federal agents before completing his demo.

Keyes is whisked off to a secret location where he joins up with fellow scientist Serge Leveque (Tcheky Karyo) and is met by General Thomas Purcell (Richard Jenkins). It seems that 32 Bostonians have simultaneously dropped dead in a ten-block radius for no apparent reason, and General Purcell wants to know if it was caused by a covert weapon. Of course, the military has been put in charge of the investigation and everything is hush-hush.

Without examining anything, Keyes takes about five seconds to surmise that the victims all died from malfunctioning pacemakers and the malfunction was definitely not due to a secret weapon. We're supposed to be impressed, but our experience with real scientists and engineers indicates that when they're on-the-record, top-notch scientists and engineers won't even speculate about the color of their socks without looking at their ankles₁. They have top-notch reputations because they're almost always right. They're almost always right because they keep their mouths shut until they've fully analyzed the data.

Naturally, General Purcell is totally satisfied with Keyes speculation and immediately dismisses him. Amazed at General Purcell's lack of curiosity, Keyes sets out to find answers. After a detailed analysis he concludes that the Earth's core has stopped spinning and is causing the Earth's magnetic field to collapse.

Keyes is apparently the only one in the world to discover this fact. (Where are all the compasses? Are there no Boy Scouts?) When Keyes  tries to share his results with world-renowned scientist Dr. Zimsky (Stanley Tucci), he's rebuffed as a mere autograph seeker. Keyes presses an overstuffed folder into Zimsky's hands and emphatically explains that it has information about the end of humanity.

Zimsky appears to be in the wrong movie. He looks and acts like a stereotypical 1930s film star. Naturally, as a world renowned scientist, he is immediately impressed by having a total stranger run up to him on the street and ask him to endorse a wild-eyed theory. He not only accepts Keyes folder but ends up carefully studying its contents.

Alas, Zimsky tells Keyes that his theory can't possibly be correct, and Keyes ends up sulking in a bar with his friend Serge. Not only is the future of humanity looking dim but also Keyes' chances for being the first to publish the prediction.

Keyes' sulking is interrupted by federal agents who again whisk him off to a secret location this time for a meeting with a whole room full of top brass. To his surprise, Zimsky is there representing Keyes' theories as his own. However, Zimsky has fallen out of favor with General Purcell and the general invites Keyes, rather than Zimsky, to address the group.

Not one to waste time, Keyes jumps straight to the bottom line: humanity is doomed and will end in a few months. The cause? Deadly microwave radiation will cook us since we'll no longer be shielded by the Earth's magnetic force field or what Keyes refers to as "Earth's electro-magnetic energy field".

Keyes proceeds to demonstrate the effects of losing the magnetic field by lighting the aerosol from a can of hair spray and flaming a peach representing Earth. He makes his explanation simplistic since he's talking to military brass who can't grasp complexity, even though they lead one of the most complex and high tech organizations in the world.

Not only does Keyes not know the difference between forces and energy but he apparently believes that electromagnetic radiation such as microwaves can be deflected by a magnetic field. Here's a quick experiment, try using a magnet to deflect the electromagnetic (EM) radiation emitted by a flashlight. The EM radiation is a beam of visible light and, although we hate to spoil the experiment, nothing will happen.

Whether Earth did or didn't have a magnetic field would make no difference as far as microwave radiation is concerned. First, the magnetic field doesn't affect it, and second, there's very little of it in the first place. The Sun emits lots of electromagnetic radiation but most of it is visible light. It sends very little microwave radiation. At its worst, the Sun's microwave radiation can cause interference with radio or cellphone transmissions but poses no significant health hazard.

The Sun does periodically emit potentially dangerous quantities of plasma during solar flares. It's made up mostly of protons and electrons with high amounts of kinetic energy which can, indeed, be deflected by magnetic fields. The Earth's magnetic field does give some added protection from the solar wind. However, even without the magnetic field the atmosphere would still effectively shield us.

There is little reason to panic over a magnetic field upset. The geological record indicates Earth's magnetic field reverses itself at irregular intervals averaging about every half a million years. While the magnetic field probably doesn't drop to zero during these times, available evidence suggests it becomes weak and erratic. Undoubtedly, some bad things happen but there's no evidence that such fluctuations cause mass extinctions, let alone incineration by deadly microwave radiation.

The movie's heroes set out to solve this horrifying non-problem in the only possible way: send a manned vehicle that looks like a windowless subway train into the Earth's core and blow up five 200-megaton nuclear bombs. (We always knew nukes were good for something.) An unmanned vehicle would make a lot more sense for such a hostile environment, but then the movie's heroes would not be able to exhibit courage, daring, and self-sacrifice.

We won't even argue the impossibility of stopping the Earth's core and will ignore the fact that the largest nuclear bomb ever built was a Russian device rated at 100 megatons₂ and weighed a whopping 27 metric tons. We'll also ignore the fact that the largest bomb currently in the U.S. arsenal is only 9 megatons₃. From an energy standpoint alone, five 200-megaton bombs wouldn't even begin to be capable of spinning a stationary inner or outer core up to full speed.

The solid iron inner core normally has a rotational kinetic energy equivalent to about 340 200-megaton bombs. The liquid metal (primarily iron) outer core surrounding the inner core has a normal rotational kinetic energy equivalent to roughly 32,000 200-megaton bombs. Assuming only the inner core had to be restarted and that 100% of each bomb's energy could be converted to rotational kinetic energy, the movie's heroes are at least 335 bombs short of the required amount.

To make matters worse, the bombs have to create a torque (roughly speaking a twisting action) on the core in order to spin it. When each bomb explodes, the shock wave would travel outward in all directions from the bomb, like an expanding sphere. When the wave hits the core, it would create a net force acting through the core's center of mass (assuming that the core is spherical and has uniform density). Forces acting through the center of mass cannot produce rotation because they produce no torque.

To create a torque, the shock wave from each bomb blast would have to travel outward primarily in a single direction tangent to core. This would require a highly specialized bomb design, if it were even possible. Any part of the blast wave which traveled in a different direction would represent an energy loss and so our best case estimate of 340 bombs would probably be low by orders of magnitude.

Construction of the subway-like ship, called Virgil, for traveling to the core involves the usual impossible feats of engineering. When asked for an estimate, the ship's inventor says it will take 12 years to complete. Instead it's done in only three months thanks to a generous infusion of government funds. Sure lots of money helps, but we suspect that accelerating the development of such radical technology would be like the old saying of trying to produce a baby in a single month by hiring nine pregnant women. 

Virgil is made of an impossible alloy capable of withstanding the extreme temperature and pressure found in the core. To its credit the movie calls the material unobtainium. While not desired, even good science fiction sometimes has to resort to pure fabrication in order to continue the plot.

For digging purposes the ship uses the usual lasers with ultrasound thrown in for good measure. Of course, there is also an amazing "MRI" vision system which can see through solid lead!

When mission training begins, we're shown the typical Apollo 13-like scenes where the "terranauts" continually make disastrous screw-ups in a simulator as the tension builds. There is obvious friction between the ship's pilot Col. Robert Iverson (Bruce Greenwood) and the ship's co-pilot Maj. Rebecca Childs (Hillary Swank). 

Earlier we saw the two in a space shuttle engaged in a juvenile argument about who was going to land it. The ever-patronizing colonel told the ultra gung-ho major she just wasn't ready (a highly original line). According to the late Richard Feynman, landing the shuttle requires the pressing two buttons: one for the destination and the other for lowering the landing gear before touchdown ₄. Details of the landing are handled by an on-board computer with no less than four additional backup systems. Of course, button pushing is no job for a rookie.

The first part of the reentry and landing has to be done by the computer because adjustments have to be made faster than humans can react. Shuttle pilots often do opt to use "manual" controls for the final descent on the theory that placing a human in the control loop increases safety. However, even when using "manual" overrides, the landing is still highly automated.

When the shuttle mysteriously went astray during the landing and completely missed its targeted site, Maj. Childs saved the day by directing it to an emergency landing site in Los Angeles. Evidently Col. Iverson would have preferred death to this bit of one-upmanship and can't bring himself to forgive her. On the other hand, maybe he's simply embarrassed by the moviemaker's ridiculously impossible portrayal of the shuttle's crash landing.

Add in the super egotist Zimsky, the philosophical Frenchman Serge, and the eccentric inventor Brazelton, all led by the brilliant Dr. Keyes who can't even tie his necktie and the Virgil has a perfect world-saving crew.  We like them just enough to feel sad as the script kills them off but not too sad since most of them aren't especially good looking or super cool. But, don't worry, the youngest, coolest, and best-looking characters are in no real danger.

The cast is rounded out by DJ Qualls who plays a stereotypical convicted computer hacker called Rat. He is brought on board for the critical task of preventing anyone on the Internet from precipitating a worldwide panic by posting theories about the impending disaster. Apparently, dead pacemaker patients, berserk window-smashing pigeons, bizarre space shuttle crash landings, monstrously powerful thunderstorms, the Golden Gate bridge collapse, unexpected nightly displays of the aurora borealis, and the total destruction of Rome, all in around three months, aren't enough to generate concern.

Besides, no TV, newspaper or radio news organization would ever speculate on such matters, let alone ask reporters or high-priced consultants to find answers. No televangelist would see anything Biblical in these signs of impending judgment nor would any private citizen be panicked without input from a webpage. The physics represented in these ominous events were pretty horrifying but even we weren't panicked. The scenes were overdone to the point of silliness.

Consider the pacemaker fatalities. A pacemaker malfunction isn't automatically fatal. In most cases the patient's heart will still beat, although with an abnormal rhythm. The severity of a pacemaker problem depends on the type of malfunction as well as the severity of the patient's condition. EM interference can cause problems, but major problems are rare considering the amount of EM interference pacemaker patients are exposed to. Pacemakers are designed to minimize these problems. It's hard to believe that dozens of pacemaker patients with various heart conditions and different makes and models of pacemakers would simultaneously die from microwave exposure.

As for the pigeons, even if totally disoriented and panicked, would they ignore their eyes and smack into the nearest screaming Londoner or window? Even if they did, it's unlikely they'd have the kinetic energy and structural strength to smash windshields. We've seen numerous birds run into various kinds of windows without ever breaking through. We once saw a large bird unwittingly fly into the windshield of a car traveling about 65 mph (higher than the top pigeon speed). It definitely wasn't the windshield that got smashed. Okay, we can't rule out a possible broken window but surely it would be rare.

The Golden gate bridge collapsed when a beam of microwave radiation shined on it through a hole in the magnetic field. It seemed as though the moviemakers got the magnetic field mixed up with the ozone layer.

Sure, the bridge would collapse if heated several hundred degrees Celsius above its normal temperature, but that's impossible. It's a massive air cooled structure. On a sunny day the bridge absorbs between 60 and 90% ₅ of all incident solar radiation, yet only feels warm. Even if the bridge absorbed 100%, it would be just slightly warmer. It makes no difference if the sun's radiation is mostly visible light or 100% microwaves. Whatever is absorbed turns into heat. The only way to get bridge-collapsing temperatures would be to substantially increase the Sun's output. Are we supposed to believe that the Earth's magnetic field can do this?

We were worried that Rat would become a terranaut. Fortunately cooler heads among the moviemakers prevailed and he was allowed to remain on the surface. Even though he was a cardboard stereotype we would have been sad to see him go on the mission. With his looks and lack of coolness it would have been suicidal.

The Virgil began its journey when it was dropped in the middle of the ocean over the Marianas Trench. This is the deepest part of the ocean and traveling through water is easier than traveling through rock. However, the trench is only about 6.8 miles deep so the distance through water is negligible compared to the total distance of the trip. The Earth's crust is also rather thick in this region since the trench is caused by an oceanic layer sliding under a continental layer of the Earth's crust. If the Virgil could really bore through solid rock with ease then why go to all the trouble of setting it up on a platform in the middle of the ocean for such a questionable advantage?

Apparently, the Virgil was perfectly weighted so that it fell nose down. We're not sure why the Virgil's ultrasound was needed for boring through water but it was turned on anyway and attracted whales like a silent dog whistle. Inspired by the ultrasound, these great beasts displayed an astonishing ability for deep diving.

After reaching bottom, the Virgil's trip into the core was also amazing. Even though the ship looked like a subway train headed downward, the terranauts were able to walk from segment to segment of the ship as though the ship were horizontal. However, this eventually facilitated the typical heart-wrenching trapped-behind-bulkhead-doors-while-the-compartment-floods scene.

During the trip, the terranauts are in constant radio communication with the surface even when they're thousands of kilometers deep inside a dense and conductive material. Radio waves simply do not penetrate to any appreciable depth into conductive materials. This is the basis for shielding communication and instrumentation wiring. The wire(s) to be shielded are wrapped with a conductive covering which is connected to ground. Stray EM interference generally cannot penetrate the rather thin conductive outer wrap.

Sound waves could be used for communication but would probably not have enough energy to work for more than a few kilometers. If a sound-based communication system did work at greater depths there would be a significant delay between the time the signal was sent and received. For example, the delay would be 200 seconds or 3.3 minutes at a depth of 1000 km, assuming the speed of sound is about 5 km per second (comparable to the speed of sound in iron).

While descending, the brave terranauts run into a void. Yes, we did say void. The pressure is a bagillion atmospheres, the temperature thousands of degrees Celsius and the surrounding material plastic in nature, yet, there's a void. As the ship ventures into the void we see geometric looking images projected on the the ship's viewing screen. As we watched the scene, we mentally searched for the most ludicrous and outrageous term to describe the void and hit on the perfect choice: a giant geode.

Later, when it looked like the movie couldn't get any more stupid, the terranauts redefined the standard. They announced that they were inside a giant geode. We were dumbstruck. Its hard to poke fun at a movie which unintentionally trashes itself.

The ship becomes jammed and the terranauts don flimsy-looking spacesuits to go out into the void and unjam the ship. Mind you, the temperature is still several thousand degrees Celsius, not to mention that the void's gas pressure would have to be several thousand atmospheres to keep the void from collapsing.  The gas would have liquid-like density which would greatly slow movement. From a temperature standpoint, it would be worse than walking around in a gigantic hollow incandescent light bulb filament (about 3000 degrees C). Everything would be glowing white hot.

Okay, maybe the suits are made of incredibly strong unobtanium and have special cooling systems with miraculously effective insulation. Are we to believe that unobtainium can also be woven into fabric and fashioned into flexible parts like oxygen hoses? Is there a clear form of unobtainitum for face masks? Surely, the movie is taking pure fabrication of scientific facts to the extreme.

When oxygen is needed for cutting a giant crystal jammed against the ship, one of the terranauts bravely detaches the oxygen line from his suit and uses it to blow oxygen into the cutting area. To do so, the oxygen pressure in his tank would have to be higher than the outside gas pressure. At those kinds of pressures, not to mention temperatures, releasing a stream of oxygen would be like releasing a stream of nitroglycerine. It would react violently with its surroundings.

The situation is reminiscent of George Gobles' famous charcoal grill lighting experiments_6. He was able to get his charcoal grill up to full temperature in three seconds by pouring around three gallons of liquid oxygen on it before lighting. The trouble was that the steel grill was consumed in the resulting fire leaving only a small pile of ash. We might add that the liquid oxygen was at cryogenic temperatures when poured on the charcoal.

Although the oxygen in the movie was at elevated temperature the pressure would have been so high it would have had liquid-like density₇ and hence an incredibly high concentration leading to an explosive reaction rate. At such conditions even iron would have violently reacted with the oxygen. Keep in mind that the primary difference in destructive potential between corrosion and an explosion is the reaction rate. Setting off the violent oxygen/mantle material reaction would not have required a match since the ambient temperature was already higher than a typical match flame.

Once underway the Virgil runs into a giant diamond (no we didn't make this up) and springs a leak. Given the outside temperature and the pressure, even a pinhole leak would be devastating. The outside material would spray into the interior of the Virgil with explosive force incinerating everything in its path. By comparison, the pressure was only about 4 atmospheres or 60 psi directly below the Hiroshima bomb blast. The temperature of an oxyacetylene torch used for cutting through solid steel is less than 3500 degrees Celcius.

Instead of an immediate catastrophe, we are served up a lengthy and supposedly heart-wrenching scene₈ in which a hapless crew member is trapped behind a bulkhead door as the compartment contracts around him like an oversized empty beer can slowly crushed by a giant bubba.

When the terranauts finally reach the core they find it's not as dense as expected and so they don't have enough bombs to start it spinning. It obviously never occurred to the mission planers to send a couple of extra bombs just in case.

Zimsky is unruffled by the problem and announces they'll just have to go back and set things right using the covert earthquake weapon which probably caused the core to stop spinning in the first place. It sounded like a much better plan to us than the one that just failed. We were wondering why they didn't try it to begin with when Keyes answered our question with another of his brilliant flashes of instant insight. Apparently, it would cause all the volcanoes on Earth to erupt.

We assumed this meant only currently active volcanoes. Such eruptions would be disastrous in their local areas but these are fairly few in number. Again, it sounded like it might be a deal compared to having the entire Earth incinerated. However, as we weighed the pros and cons, the plucky terranauts devised yet another plan.

Unfortunately, the plan required sacrificing a crew member who had to enter a duct with a temperature of "9000 degrees" wearing only a suit designed to resist "5000 degrees". For comparison consider that the temperature underneath the Hiroshima bomb was about 3900 degrees Celsius or 7000 degrees F. At 9000 degrees C or F the walls of the duct would be glowing with a bright white light. Walking into it would be worse than walking into a nuclear bomb blast. By comparison the movie depiction is outright silly.

While the terranauts busy themselves implementing the new plan, the heartless numskull Purcell decides to fire the earthquake machine anyway. Rat realizes that this would be fatal for the brave terranauts and sets out to foil the General's plan. Judging from the graphics and error messages on Rat's screen, he does this by searching the Internet. Apparently, the government had set up a special webpage with all the necessary super secret information for just such an emergency. Rat not only finds it but gains access to America's electric power grid control system and reroutes the weapon's power, all within minutes; what a guy.

Once again, the terranauts screw up their calculations. The last bomb needs 40% more explosive energy or the mission will fail. Keyes pulls the plutonium fuel rods out of the ships reactor and sets them next to the bomb to compensate. The rod assembly is so hot it melts through an attached chain which must be made of lead since it doesn't glow as it melts.

Keyes hands are slightly burned as he pulls out the plutonium rods. Evidently his unobtainium spacesuit gloves have malfunctioned. However, it can be forgiven since his suit shielded him from the radiation emitted by the plutonium undergoing fission in the ship's reactor, even though he was not wearing his helmet.

Even if the plutonium placed near the nuclear bombs did detonate, it would be a fission reaction which would not provide anything even close to 40% of the energy in a 200 megaton bomb. The larger bomb would have to be a hydrogen bomb based on an entirely different type of nuclear reaction, namely fusion.

After removing the reactor's fuel rods, the remaining terranauts are stranded with no power source, only 12 minutes from certain death due to the blast wave, but don't worry. The unobtainium hull of the ship conveniently converts heat to energy. In the remaining 12 minutes they pull the ship's power wires loose and solder (?) them to the ship's inner hull. The ship magically powers up and the terranauts surf the blast wave to safety.

We're left with many questions. First where's the circuit? To produce power, current has to flow and this requires a voltage drop. If one wire is hooked to the ship's hull which supposedly acts as a high-voltage source, then where is the ground wire connected? Even if the circuit did exist, how could the unobtainium possibly produce exactly the right kind of power (AC verses DC) at the correct voltage just by dumb luck? If it's so easily done then why wasn't the ship designed with unobtainium backup power in the first place?

After surviving the bomb blast, the remaining terranauts end up trapped alone in yet another impossible situation. The movie has imitated a long list of action/science fiction scenes from all kinds of sources including The Birds, Independence day, Armageddon, etc. Surely now it's time for a romantic James Bond-like ending which lightens the mood and winks at the thought of taking anything seriously, but no, this is not just a disaster movie. It's a disaster.

The movie ends with Rat taking over a computer network so that it displays cutesy graphics and spams the world with news of the brave terranauts who have sacrificed greatly to save humanity from certain death. Why yes, we too believe everything in the unsolicited e-mail we receive. What Hollywood gives us in The Core is almost as convincing.