The Core

The Core

    Over the past few years, there's been an emphasis on strengthening and concentrating on your core during workouts, the "core" being your inner support muscles, the stomach, the back and the surrounding muscles.  But if there was one woman I forgot to mention in the last post on women, it was Inge Lehmann who truly began the core movement of today but did so way back in 1930...and it had nothing to do with exercise.

    As a Dutch seismologist, Inge Lehmann defied all odds by publishing a paper on deflected P-waves, waves that penetrated the earth through its core and emerged in a different location.  Contrary to accepted theories, the earth's core was solid, she wrote.  The reaction to her paper was less than excitement; in fact, it wouldn't be until 1970 --some 34 years later-- that Inge Lehmann's paper was proven to be true (she kept publishing scientific papers until she was 98 and passed away in 1993 at the age of 104).

    Some of what she went through is understandable, for many of us have grown up with a belief that the center of the earth is liquid, an area so hot that magma and other volcanic materials emerge regularly to remind us of such.  Jules Verne and others journeyed imaginatively to "the center of the earth;" and even as children, we were told that if we only dug deep enough, we would emerge on the other side of the planet.  But truth is, we've tried...for decades.  And we're not even close.  In fact, both Russia and the United States have given up their efforts.

    As an article in Discover says: “Going into space is just a lot easier than going down for an equivalent distance,” says David Stevenson, a geophysicist at the California Institute of Technology.  “Going down from 5 kilometers to 10 is much harder than going from zero to 5.” All the mines on Earth, all the tunnels, caves and chasms, all the seas, and all of life exist within or on top of the thin shell of our planet’s rocky crust, which is much thinner, comparatively, than an eggshell.  Back in 1970, the Soviets began work on drilling in the Kola Peninsula, a remote area in northwest Russia.  For 24 years they drilled, hitting rock a billion years older than the earliest rocks at the bottom of the Grand Canyon.  The rock they drilled was so viscous that when a drill was removed the hole would fill.  By the time the project was abandoned 24 years later, the drill had --with considerable effort-- reached a depth of 7.6 miles, deeper than what Mount Everest would be, but: still a minuscule distance, considering Earth’s 7,918-mile diameter.  If Earth were the size of an apple, the Kola hole wouldn’t even break through the skin.

Graphic Illustration from Discover Magazine

   What was interesting about this piece in the magazine, written back in 2014, was that even with today's equipment, finding out about our planet's core via a probe or drilling is likely to never happen.  So we turn to P-waves and S-waves, seismic waves that easily move through our planet, going where we can't in fractions of a second.  And because the waves showed something solid deflecting them, the position taken was that our earth's core had something solid in its center.  And that core (about the size of our moon) is likely a solid mass of iron.

Illustration: Roen Kelly, Photo: A. Varfolomeeviria Novosti

    Surrounding all of this (and what hampered all the drilling efforts) is a massive swirl of liquid iron and nickel, a layer almost as thick as the mantle above it which is about another 1800 miles thick;  and above all of that --our mountains and cities and underground subways and mines-- is our crust, a relatively thin 5-25 miles thick.  But as incredible as that is (a solid core of iron as hot as the surface of our sun and resting in a molten pool of iron) is that all of it, yes all of it (even our crust) is moving...and it is what is keeping us alive.  Without that movement, our planet would be as lifeless and desolate as Mars or Venus, a chunk of radioactive mass joining the orbits of other such masses around our sun...for it is that sun that is both the harbinger and destroyer of life.

    Solar radiation is constant, and life (as we know it) destroying.  Water evaporates, the atmosphere dissipates, life fails.  Add to this the solar flares that erupt frequently, blasting even more powerful surges of solar radiation (you've likely seen or heard about those images, the radiation shooting millions of miles out into space at incredible speed, something that orbiting satellites have to be shielded from as best they can lest their instruments succumb to the influx).  Earth has the same problem as the satellites but with one major defense...a magnetic field.  And where would that be coming from?   From movement within, a age old massive internal iron engine still going strong some 3.5 billions years later.
   
    This mystery of what is and isn't necessary for life is still puzzling scientists.  It may be that several seemingly disparate phenomena were essential in making Earth a habitable world: the formation of the moon, the planetary magnetic field, plate tectonics and the presence of water.  Without the collision that created the moon, there wouldn’t have been enough heat for convection to start in Earth’s core and power the magnetic field.  Without water, Earth’s crust might have remained too strong to be broken up into tectonic plates; and without a tectonically fractured crust, too much heat would have been trapped inside Earth.  Without Earth being able to cool, there would have been no convection and conduction (essential for the magnetic geodynamo, as it's termed, to operate).

    It's rather like us, isn't it?  Working on our core strengths, watching our outer bodies tighten and grow firm while having little insight into our inner core (at least, until we're operated on and even then, not being awake to witness anything).  Always looking outward and rarely inward, perhaps never to know.  But beyond that, beyond our physical core, might be something equally puzzling, even to ourselves.  Perhaps it is all of these cores that were necessary to also form "us."  Perhaps we humans also needed certain elements to come together, perhaps something far beyond mere minerals and gases, something so solid inside that we still find it impenetrable, and perhaps something we've yet to reach...