September 8, 2008 | David F. Coppedge

Modeling Just-So Stories for Earth History

Models are only simulations of reality.  In science, they have a long history of simplifying complex physical phenomena in an attempt to understand them.  Many times, empirical evidence can correct a model.  The model then becomes a more accurate simulation, and can even provide additional insights and make predictions.  Can modeling work for the unobservable, unrepeatable past?
    A story posted on has a title like a Kipling fictional story: “Why Early Earth Did Not Freeze.”  Reporter Aaron L. Gronstal for Astrobiology Magazine addressed a well-known puzzle in climate history: how the early earth prevented a deep freeze.  According to stellar evolution theory, stars like our sun begin with much lower luminosity.  Four billion years ago, the sun would not have had enough energy to keep Earth’s oceans from freezing.  Yet evolutionists and geologists believe that the earth had liquid oceans at least as early as 3.7 billion years ago.  This is the “faint young sun paradox.”  Geophysicists and climate historians have proposed more “greenhouse effect” or meteor bombardments to warm the earth, but without convincing success.  Most doubt that there could have been enough carbon dioxide, methane or ammonia to provide a space blanket.
    Gronstal reported models by German scientists that reduce the amount of carbon dioxide required to heat the earth.  “The model showed that a partial pressure of only 2.9 millibars of CO2 would have been needed during the late Archaean and early Proterozoic periods in order to bring the surface temperature of the Earth above freezing,” the article said.  “This result, although contrary to previous studies, agrees with current geological data.”  The paradox thus disappears.
    Whether this claim will have ripple effects on assumptions about the impact of carbon dioxide remains to be seen.  Will it renew fears about global warming?  What does it mean to other geological periods when life was present?  And a question for philosophers of science: what was driving the model – the physics, or the assumptions of stellar and geological theories?
    Another geology news story is shaking up the world – so to speak.  National Geographic News claimed that continents get pushed, not sucked, into place.  This new idea, “contrary to accepted theory,” rearranges ideas about a theoretical supercontinent named Pangaea that split up 200 million years ago on the evolutionary timeline.  This “provocative” new theory pictures the continents moving back-and-forth like an accordion, instead of by the suction of deep ocean basins.  Maybe a superplume of magma in the mantle is the driving force.
    Yet the article includes doubts that geologists know any of this, because like the climate story above, it is based on models:

This accordionlike action, dubbed the Wilson Cycle, has been recognized for more than 40 years, but the forces responsible for it are unknown.
    Moreover, if current models thought to be responsible for these movements were applied to a 500-million-year-old Earth, they would not produce Pangaea in the right configuration.
    Why this reversal happened is unclear, and that’s disconcerting, [J. Brendan] Murphy said, because even though Pangaea is the best studied of the supercontinents, “something happened that we don’t understand.”

Murphy agreed that his model is “speculative.”  Applying the model forward, he said it makes Earth’s future “a lot more fun to study” even though he could never know the outcome, because a new supercontinent wouldn’t form for 75 million years.
    National Geographic quoted Murphy explaining where continental motion fits into grand schemes of evolution.  “Most people believe that for at least the last two and a half billion years, the Earth’s history has been dominated by the amalgamation, breakup, and reforming of supercontinents,” he said.  “It really is an underpinning of the evolution of the planet.
    The new ideas were reported also in a short article in Science Daily called “Pangaea Conundrum.”

With the faint-young-sun story, we have another case of a contradiction that should have falsified a belief being circumvented by tweaking a simulation.  And with the Pangaea story, we have geologists playing games on the job.
    This is like what the evolutionary biologists do with their in silico organisms (imaginary life-forms that can evolve in ways real organisms never could).  Climate is very complex and difficult to model, even for today’s weather.  Can these scientists really know what carbon dioxide did to the earth 3.9 billion years ago, without going back there in a time machine?  How many other factors (clouds, outgassing, feedback mechanisms) could have swamped the effects of carbon dioxide? (for instance, see this article on EurekAlert that explores possible effects of giant ocean eddies that might have a “profound influence on marine life and on the earth’s climate”).  How justifiable is it to run present observed continental motions back recklessly for billions of years into the past?  The observation-to-assumption ratio is so small it is like homeopathic medicine – one molecule of data in a swimming pool of speculation.
    Models that cannot be checked with empirical data become playgrounds for storytellers.  Never are these astro-geo-biologists content to follow the evidence and say, “Well, I guess the earth couldn’t be as old as that.”  No way; they have their timeline, with its mythical Late Heavy Bombardment, First Oxygenation Event (after the mythical Origin of Life), mythical supercontinents Pangaea, Rodinia and Gondwana (which sound like characters in an earth religion), and all the subsequent Darwinian fables that ride on top.  When a contradiction threatens the Grand Myth, they can always invent simulations that can be tweaked and forced sufficiently to match their hard-core, unalterable beliefs about billions of years and evolution.  Models become their carts before the observational horse.  Who needs a horse?  They have horseless carriages, driven by the gas of imagination, polluting the atmosphere of knowledge.
    Whether this is Model A or Model T, we don’t know.  Even a broken flivver can be pushed if it won’t go on its own and the horse is going in the other direction.

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Categories: Physics, Solar System

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