Criticism always abounds when a movie having even a remote reference to science makes its debut. The Core is no exception. Web sites denounce its validity, some calling it absurd and others "monumentally dumb" (NY Times).
Because Science Fiction is the genre into which one would categorize The Core,
the implication is that facts are not the issue but rather entertainment, adventure,
and surrealism are the paramount concerns. One can be thoroughly entertained
by the film despite scientific impossibilities and blunders.
Within the realm of Sci-fi movies there is no bad Physics, bad Geology or bad Biology.
However, on the flip-side, a scientist cannot help but notice errors in the very movies he/she may be enjoying. Finding blunders does not necessarily detract from enjoying the film. On the other hand, it makes watching it even more fun and challenging.
In defense of the critics, it is a good thing to present truths and expose the impossible to the public in the interest of "good science". Such a belief is the basis for this document.
So, enjoy the movie but know the scientific facts!
|Interior of the Earth|
|The earth's interior was described and explained accurately
in the movie.
We know the structure of Earth's Interior from observing the behavior of seismic waves generated during earthquake activity. The main divisions are the: crust, mantle, outer core and inner core. The mantle is further subdivided into zones based on seismic wave activity, these zones being the: upper mantle, asthenosphere and the stiffer lower mantle.
It is true that the outer core is a rotating fluid, the composition of which is most likely dense iron and nickel. The inner core is solid.
Click the image to the left to enlarge it in a new window. (Image Courtesy of: USGS)
|It is true that the crust we live on is the thinnest part
of Earth and that it is the least dense rock: 2.7-3.0 g/cm3.
As stated in the movie, we have drilled into the crust to extract core samples for study and it is factual that scientists have only been able to penetrate about 10km (6.2 mi) into the crust to the top of the upper mantle but to date no one has drilled down into the mantle. Core samples are done into oceanic crust since it is thinner than continental crust. Continental crust averages 40 km to 70 km (24.9 - 43.5 mi) in thickness beneath the Himalayas while the thickness of oceanic crust averages 7 ±1 km (4.3 - 5 mi). See How Thick is the Earth's Crust? for an image of global crustal thickness using contour lines.
No one has ever been able to drill into, let alone travel down into, the depths of the mantle itself. Mantle rock is extremely dense, owing to the increase in pressure of overlying rock material. Pressure increases with distance from the crust to the cores of the earth.
Observe the Earth's Interior image to the left where both the densities are given as well as a graph illustrating the increase in pressure with corresponding increase in depth.
Click the image to the left to enlarge it in a new window. Image Courtesy of: New York State Board of Regents Examinations 2001.
|Earth's Liquid Outer Core Rotates|
|Absolutely! Extremely high temperatures in the liquid
outer core drive a circular transfer of heat known as convection currents.
The fluid core, with a radius of 2200 miles, is always in motion, spinning
once a day at about 550 miles per hour at the outer edge of the equator.
The exact motion of the outer core fluid is not fully understood. Some researchers
have linked rotation of Earth, due to "original spin" at the time
our solar system formed, to the rotation of the outer core.
"Circulating magma in the molten outer core generates a weak magnetic field, which the researchers suspect may be leaking into the inner core and generating an electric current. The twisting force generated by this electromagnetic interaction may be what drives the inner core's rotation".1
Image: Interior of the Earth; Dr. Pamela Gore
|Earth's Magnetic Field|
|Yes, Earth has one. That is factual. It is also true that
the magnetic field is generated by the rotation of the dense, iron, liquid
outer core and that this field extends about 126,000 meters (approx. 78
miles) out into space. As the outer core fluid is driven by convection currents,
a dynamo effect of circulating electric current is produced inside Earth,
exactly as Professor Keyes explained in the movie.
Notice that the North Magnetic Pole is not the true Geographic North Pole. There is a declination of about 12°. The magnetic field exits the South Geomagnetic Pole and enters Earth at the North Geomagnetic Pole.
The geomagnetic field protects us from harmful charged particles emitted by the sun.
In fact, fluctuations in the strength of our magnetic field, due to intermittent solar flares, sometimes allow more cosmic radiation to reach Earth. An increase in cosmic radiation can temporarily affect power grids, cable and satellite reception and communications systems on spacecraft, enlarge atmospheric ozone holes and generate more aurora activity.2
Such fluctuations are temporary and small in scale. Larger magnetic fluctuations, called Magnetic Reversals, where the North and South Magnetic Poles flip their positions, have occurred many times in Earth's history, (171 times in the last 71 million years, according to scientific evidence). The average interval of magnetic field reversal is approximately 250,000 years. However, the last magnetic reversal happened approximately 730,000-780,000 years ago. Throughout all of geologic time, there is no evidence that the Electromagnetic Field ever ceased to function, or that the outer core ever stopped rotating as depicted in the movie.
Earth's Magnetic Dipole image: © 2003, Professor Kenneth R. Lang, Tufts University.
Click the image to the left for a larger and different view.
Auroras - High Altitude Static Discharge
Auroras do exist and High Altitude Static Discharge is factual. When super charged particles enter the earth's atmosphere from the solar wind they tend to be channeled toward the poles by magnetic forces causing them to spiral around the magnetic field lines of the earth. They are energetic enough to ionize air molecules, so a considerable number of atoms and molecules are elevated to excited states. When they make the transition back to their ground states they emit light characteristic of the atoms and molecules. Red and green light emitted from oxygen atoms is a constituent of the light seen at the poles. Atmospheric nitrogen also plays a role. An example of the colors that might be visible can be found by observing the nitrogen spectrum. Near the North Pole the light show is called the aurora borealis and near the South Pole it is called aurora australis.
Mariana Trench - Point of Entry for the Terranauts
The Mariana Trench (a.k.a. Marianas Trench) is the deepest submarine trench
as well as the deepest location in Earth's crust. The trench is 10,911 m (35,798
feet) below sea level.
Although it may seem odd to list a point of entry for Virgil as part of the "Good Geology" section, it appears here because, if a ship could travel to Earth's core, then what better location to begin a journey?
This trench is not only closer to the ship's final destination but also a spot where the oceanic crust would be thinner and a ready-made crack, the trench itself, is present in the lithosphere where the Pacific Tectonic Plate is subducting under the Philippine Plate.
However, the absurd side of the whole idea is that, although the Mariana Trench is a "bit" closer to the core than other locations might be, the overall distance that must be covered from the crust to mantle-core interface is so great that it virtually nullifies any advantages the Mariana Trench might offer.
Outer Core Ceases to Rotate
Can the outer core stall and cease to rotate? In the movie, the reason for a cessation of motion was not a natural phenomenon. Rather, human interference, in the form of Project Destiny, was to have been the cause. Obviously, this is one of the science fiction aspects of the film and it cannot be argued. It is just part of the story. So, in reality, the outer core did not stop moving of its own accord. It was interfered with. Is it possible for people to control such a huge mass of hot fluid 2,900 km below earth's surface? Given today's technology, in a word, no. However, it certainly did make for an exciting concept around which to base the movie.
Earth's Magnetic Field Totally Breaks Down
As long as the outer core is rotating and generating the electromagnetic dynamo which creates the Magnetic Field, then there will be no break down, nor decay, of this geomagnetic protection. Of course, the premise in the film was that the outer core did stop moving. In that case, how would the Magnetic Field be generated? Once again, this is the fictitious part of the story.
Empty Space in the Mantle?
Take another look at the pressure reference chart in the Interior of the Earth section above. The pressure from overlying rocks increases the density of the rocks below. With an increase in depth, there is an increase in pressure and an increase in the density of rocks. How could there possibly be cavities of empty space within such a dense mantle? Pressure is 3.5 million times the pressure at Earth's surface. In fact, at the outer core-inner core interface, iron solidifies even though temperatures are 11,000 degrees F. An increase in pressure raises a substance's melting point. This is the reason for the solid inner core, despite the fact that it exists at higher temperatures than the liquid outer core does.
Amethyst Crystals Deep in the Mantle?
Dr. Keyes is amazed by the huge crystals inside the large mantle geode, or as Keyes put it "Gem Bubble", in which Virgil broke down. Nimsky states the crystals are Amethysts. As stated in the section above, empty space in the mantle is dubious indeed. But, amethyst crystals at a depth where temperatures are 5,000-9,000°F? Amethyst is a variety of the mineral quartz, (silicon dioxide, SiO2). Bowen's Reaction Series clearly indicates that the first mineral to melt, also the last to form, in a series is quartz. Quartz is stable at surface conditions and unstable under great pressure and at depth. How would quartz crystals withstand the 9,000 degree temperatures and tremendous pressure so deep inside Earth, even if there were a cavity in the mantle? Mantle rocks are mafic in composition. They are abundant in the minerals pyroxene and olivine and lacking in the minerals quartz and orthoclase feldspar. And so, quartz-rich crystal formations have no business growing in the mantle in the first place. Of course, the fictitious large crystals made it a gorgeous place to break down, albeit dangerous.
Molten rock begins to pour into the large geode where Virgil became stuck on
a large crystal. Panic sets in and an immediate exit is critical. Dr. Serge
Leveque says, "At this rate we have 2 minutes before the lava gets us".
Magma is the term for molten rock inside the earth and Lava is the name for molten rock when it flows on earth's surface. Therefore, the term lava was incorrectly used in this situation.
Heard in the Control Center:
" The 2 Terranauts Found a Space between 2 Tectonic Plates Somewhere Near Hawaii"
Hawaii is located within one tectonic plate, the Pacific Plate. The Hawaiian
Islands formed from Hot Spot Volcanism, an unusually hot area in the mantle
which causes partial melting of the upper mantle and oceanic crust as a tectonic
plate passes over it. The mantle is stationary but the plate moves. This results
in volcanism that forms chains of islands (Volcanic Island Arcs).
Two tectonic plates do not meet at Hawaii. What may exist are cracks in the crust through which magma erupts. Better to have said that the terranauts simply road the magma flows until they exited at one of the cracks caused by Hot Spot Volcanism rather than imply that 2 lithospheric plates were responsible for an available exit.
Lasers Going In, Yes - Lasers Coming Out, No
Virgil's lasers were used to break through all that dense rock material on the terranaut's journey to the outer core. How amazing that the remaining 2 terranauts were able to make the return trip without them. It was almost as if the diamonds that had to be dodged on the way in, no longer presented a hazard.
Pacemakers Cease to Function and People Die
In the film, people who had pacemakers died of heart failure. Does a fluctuation
in the geomagnetic field interfere with a pacemaker?
Older pacemaker models actually used microwaves to communicate with the pulse generator allowing the reprogramming of the instrument. Newer models are not affected by microwaves. Arc welding and digital phones may affect pacemakers but the microwave oven is no longer a hazard. In the film, the sudden death of people due to an increase in solar microwave radiation reaching earth due to a breakdown of the magnetic field would have been more possible with earlier pacemaker models.
However, the assumption is that the geomagnetic field could decay to a point where excessive solar radiation would reach Earth in the first place.
Birds, Affected by Changes in Earth's Magnetic Field, Fall from the Sky
"A number of Earth's creatures, including some birds, turtles, and bees, rely on Earth's magnetic field to navigate. The field is in constant flux, scientists say. But even without it, life on Earth will continue, researchers say".3 Since the magnetic field has never totally disappeared and, since the last magnetic reversal was 730,000-780,000 years ago, scientists have no significant empirical data, based on clinical observations of birds in flight, to accurately assess just how much animals would be affected if the magnetic field actually ceased to exist.
|A Person Can Walk in 9,000°F Core Fluid and Survive Long Enough to Override a Compartment Ejection System|
|Click the image to the left to enlarge it in a new
The diagram shows a cross section of the earth and a graph showing temperature increase with depth. An arrow, with Celsius and Fahrenheit temperatures has been place at the core-mantle interface to show how hot it would have been when Dr. Brazzelton took his walk in the core fluid. He was the unfortunate, though willing, victim of "drawing straws" to see who would sacrifice their life to allow compartments of Virgil to be ejected. He had to go into a compartment, filled with 9,000°F (4,982°C) outer core fluid to disable electronic equipment. By his own admission, the suit he would wear could withstand half that temperature. So, it is safe to assume he would be unprotected at 4,500 degrees of intense heat.
As he proceeds into the fluid-filled compartment, his shoes melt, his glasses break and his face lights up like an incandescent bulb. But, no way could he have made the walk and accomplished the task, which in all took several minutes. Under those extreme conditions, it is safe to say that the human body would succumb to the effects of 4,500 degree heat immediately. Consider how, even here on Earth's surface, on summer days when temps reach over 100 degrees, people suffer heat prostration. Image Courtesy of: New York State Board of Regents Examinations 2001.
Microwaves Cook the Golden Gate Bridge
The majority of the sun's radiation reaches Earth in the form of visible light.
There is little incoming microwave radiation and the Earth's magnetic Field
does not affect it. It is known that microwave radiation can interfere with
radio and cellular transmissions however health hazards have not been an issue.
Should there be no Magnetic Field at all then incoming solar microwave radiation
would still not be strong enough to incinerate and collapse the Golden
Gate Bridge. Earth's atmosphere plays the primary role in shielding us from
the harmful effects of the Sun. In the geologic past the Earth's magnetic Field
has reversed many times and even weakened in strength yet there is no evidence
supporting a biohazard or major extinction event during those time periods.
While it is true that incoming solar radiation is converted to heat upon reaching Earth's surface, the bridge itself is an air-cooled structure that would have to heat several hundred degrees Celsius above normal temperatures to come close to collapsing and this is virtually impossible considering the Sun's size and radiation output.
The Terranauts Remain in Radio Contact with Base Command
Sound waves can travel a depth of a few kilometers at best. Yet, from thousands of kilometers within the Earth the terranauts communicated with their Control Center on Earth's surface. Ongoing communication in this type of situation is dubious if not impossible.
Virgil is Stuck on a Geode Crystal
While traveling through a supposed geode located deep in Earth's Mantle, Virgil becomes stuck on a large crystal. The terranauts bravely exit the ship where temperatures are several thousands of degrees Celsius and the pressure inside the geode would have to be at several thousand atmospheres in order to keep the geode from collapsing. Nonetheless, in their unobtanium suits, the terranauts work to free Virgil from its unfortunate jam. To cut the giant geode crystal oxygen from one of the terranaut's life-support systems is used. However, in order for the oxygen to flow from the oxygen tank it would have to be at a greater pressure than the surrounding pressure in the geode. Another thing to consider is that at the increased temperatures and depths where the oxygen was used, reactions would be considerable different than those encountered on Earth's surface. In other words, explosive reactions between the oxygen and the surrounding environment, even with iron, would result in catastrophic disasters for all concerned.
Virgil is Struck by a Diamond
At one point during in the film Virgil sideswipes a diamond and suffers a breech in its hull. At such temperatures and depths a pin-sized hole would be catastrophic. Consider how when an airplane door is accidentally opened while the aircraft is in flight, contents inside the plane end up outside the plane. Extreme differences in pressure transfer objects from areas of high pressure to areas of lower pressure and may even result in collapse. A hole in Virgil's hull would have surely meant an onslaught of mantle material into the ship and the ultimate incineration all the terranauts.
For more on the Physics aspect of The Core, visit the following web site The Core (2003), Intuitor which details the "Bad Physics", in fact the horrible physics, portrayed in the movie. The facts cannot be summarized in this document as well as they are explained by the author of the web page.
Reversals: Fact and Fiction, NASA
Magnetic Reversals: Back to the future? NASA
Magnetic Variations NASA
Bowen's Reaction Series, Geodiscoveries Animations, Volcanoes and Igneous Rocks
NASA's Cosmos, Earth's Magnetic Dipole, Professor Kenneth R. Lang, Tufts University, 2003
The Earth's Magnetosphere, Enchanted Learning
At the Earth's Core, The Geophysics of Planetary Evolution, Dr. Bruce M. Peret
Science @ NASA, Cracks in Earth's Magnetic Shield
Earth's Magnetic Field Is Fading, John Roach for National Geographic News, September 9, 2004
Seismological Laboratory, Earth's Interior, J. Louie, 10 Oct. 1996
Glencoe Online, Ask GeoMan..., What is Bowen's Reaction Series?
National Geophysical Data Center, NOAA Satellite and Information Service, Geomagnetic Field Frequently Asked Questions
Inside the Earth, Enchanted Learning
Interior of the Earth, Dr. Pamela Gore, Georgia Perimeter College, Clarkston, GA, March 4, 2005
Magnetic Field of the Earth, R Nave
Earth's Core Crystal, CNN, Ronald Cohen and Lars Stixrude, Carnegie Institution of Washington, July 1996
LiveScience Technology, Hole Drilled to Bottom of Earth's Crust, Breakthrough to Mantle Looms, Robert Roy Britt, LiveScience Senior Writer, 07 April 2005
LiveScience Technology, Earth's Core Rotates Faster than Surface, Study Confirms, Ker Than, LiveScience Staff Writer, 25 August 2005
The Interior of the Earth, Eugene C. Robertson, USGS, 07-26-01
British Antarctic Survey, The Earth's Crust, Natural Environment Research Council British Antarctic Survey, 2004
USGS, USGS Frequently Asked Questions Question: What do we know about the interior of the Earth?
Science News Online, Core Concerns: The hidden reaches of Earth are starting to reveal some of their secrets, Richard Monastersky, October 19, 1996
The Harvard University Gazette, Putting a New Spin on Earth's Core, William J. Cromie, Gazette Staff, August 15, 1996
NMT, Geophysicist Tobin on Research Cruise, George Zamora, Updated: 2000/08/30
Fly Light, Atmospheric Electricity, Auroras, Aviation Meteorology, John Brandon, 2000
Pacemakers, 1997 HeartPoint, Updated February 1998
The Core (2003), Intuitor 2003
At the completion of this document in 2006, all of the above reference links were active and fully functional. They will, however, not be maintained.
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