One of the nice things about science is that it allows us to understand the parts of the universe that are beyond common sense.
Don't get me wrong, common sense is often a decent guide to figuring things out, and there's some truth to the lament that it'd be nice if it were more common. The problem is, our intuitive grasp of how stuff works evolved in the context we live in -- moderate sizes and masses, moderate speeds, and moderate time durations. Get very far out of that context, and common sense can give you the wrong answer. One of the first times I ran into this was in high school physics, where I learned the startling fact that an object's vertical and horizontal velocity are entirely independent of each other. This is illustrated by the oft-quoted example that if you fire a bullet horizontally, and at the same time drop a bullet from the height of the gun's barrel, the two bullets will hit the ground at precisely the same time (assuming level terrain). It may seem counterintuitive, but it's true -- and it took Isaac Newton to show why that was.
We run into problems not only when we deal with things moving quickly, but when they're moving slowly -- so slowly they appear not to be moving at all. I got to thinking about this when I was sent a link by my friend, the awesome author Andrew Butters (you should follow him at the link provided, and also immediately order his phenomenal new novel Known Order Girls, which is one of the most poignant books I've ever read). Andrew is, like me, a science nerd -- we were both drastically unsuccessful physics majors in college, who despite that experience maintained a deep fascination with how the universe works. (Interestingly, our comeuppance as incipient scientists came in different classes. His nemesis was Electromagnetic Theory, and mine was Classical Mechanics. In both cases we passed the class largely because the professor didn't ever want to see our names on his roster again, and afterward we both decided that maybe a career as a physicist was not in the cards.)
In any case, this time the topic he sent me was geology -- in particular, plate tectonics, a particular interest of mine. Researchers have just found that a part of Nunavut, Canada is actually a microcontinent -- a geologically-anomalous piece of continental crust that came loose from Greenland and welded itself to North America on the other side of the Davis Strait.
What's curious about this is that up until about 45 million years ago, Canada and Greenland had been moving apart. The evidence is that there was a rift zone -- that's what formed the Davis Strait in the first place -- and that some time in the Mid-Eocene Epoch, the rift failed. (This is not that uncommon; there's a good possibility that the Cameroon Line and the New Madrid Fault are both failed rift zones.) In any case, after the Davis Strait Rift sealed back up, Greenland started moving in tandem with the North American Plate -- except for a piece of it that sheared off and stuck to what is now Canada.
"The reinterpretation of seismic reflection data offshore West Greenland, along with a newly compiled crustal thickness model, identifies an isolated terrane of relatively thick (19–24 km [12-15 miles]) continental crust that was separated from Greenland during a newly recognised phase of E-W extension along West Greenland’s margin," the team wrote. "We interpret this continental block as an incompletely rifted microcontinent, which we term the Davis Strait proto-microcontinent... As our seismic reflection interpretations indicate an extensional event in the eastern Davis Strait between 58 and 49 Myr, spatially coincident with the zone of thinnest continental crust between the continental fragment and Greenland, we infer this extensional event [rift] led to the separation of this fragment from Greenland."****************************************
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Resistance to Wegener's contention was not willful blindness; it was lack of possible mechanism, because it never even occurred to anyone that the mantle could be demonstrably solid on one time scale (earthquake P waves) but liquid enough to support convection currents on another time scale. This has occurred many times in the advance of science, as in being wedded to the common sense notion of time (before relativity); and as valved reciprocating pumps and Jaccard looms needed to be invented before (respectively) William Harvey, and the information-based understanding of inheritance.
ReplyDeleteAs the fairy-believing author should have written "When you have eliminated the impossible, and what remains is extremely improbable, you are clearly suffering from a failure of imagination"