In the previous post, we discussed how Occam’s Razor is of little use in some arguments, leading to the principle of least astonishment. But here GG would like to suggest that the shear immensity of geologic time means that Occam sometimes cuts us off from explanations we need to consider.
In this case, let’s talk Laramide. Orogeny, that is, the creation of the Southern Rocky Mountains between something like 75 and 45 million years ago. The prevailing explanation is that the subducting ocean floor only went down to about 100 km or so and turned flat, interacting with the continent in a way to make mountains far from the plate edge. It is a nice compact explanation.
The thing is, there are a lot of places where slabs today are flat and none of them produce anything of the scale of the Laramide Orogeny. Closest are the Sierras Pampeanas in Argentina, which are far closer to the trench than the Laramide ranges were, among other difficulties. Even looking over past orogenies yields few plausible rivals–maybe the Alice Springs orogeny in Australia, or if you push things hard, perhaps the Atlas ranges in northern Africa. Or, of course, the Ancestral Rockies in almost the same place as the Laramide. But these are just as cryptic and far less common than all the events that created the Appalachians, or the Urals, or the Caledonides, or the bulk of the Alpine-Himalayan system.
Perhaps, when we encounter oddities in the past, we need to recognize that something unusual happened, meaning that Occam’s bias for parsimony might in fact be precisely the wrong bias. For instance, somebody walks up and says they will flip a coin ten times and it will come up heads. He asks a passerby for a coin and then does as he says. Parsimony says this was luck, but perhaps a better explanation is that it is a trick either involving an accomplice or sleight-of-hand [scientists are suckers for sleight-of-hand, as the Amazing Randi often showed].
Given the number of times slabs probably have been flat and given the far rarer production of mountain ranges far from the trench, maybe our bias for parsimony should be relaxed–odd and unusual results might demand more than a single cause. Maybe things were a bit Rube Goldberg-ish for awhile. In a similar vein, some workers are arguing that the impact ending the Cretaceous was so effective not just because of its size but because of the sulfur-rich rocks it hit (this in part a response to the absence of other impacts in causing extinction events and other extinction events seemingly lacking a coincident impact). Arguably something like this has or will emerge in explaining how one branch of the great apes led to humans despite lots of earlier evolutions of animals failing to reach a similar end. We often focus on the positive outcome–the mountains made, the extinction that happened–and miss how often the simple explanation predicts something that didn’t happen (kind of like the old quip that the stock market predicted nine of the past five recessions). We don’t ask, why are there no mountains in Iowa, for instance; we ask, why are there mountains in Colorado? But perhaps we need to ask both.
Occam reminds us to be distrustful of overly-complex explanations, but maybe we need to be careful not to demand too much simplicity. All theories will conflict with some observations in some way; there are always strange things that happen that are coincidences or results of unrelated phenomena. This reality means that no theory will fit every possible observation; what’s more, we tend to accept more misfits for simpler theories (for instance, the half space cooling model for ocean floor topography is widely accepted despite all the oceanic plateaus and seamounts one has to ignore to get a decent fit). Given that, we should wield the Razor more carefully least we cut off our theoretical nose to spite our parsimonious face….
A favorite shortcut employed by many in trying to decide between hypotheses is to enlist Occam’s Razor–that the simplest explanation for something is most probably right. Now this has strength because humans are pretty good at rationalizing notions they put forward, adding in new ingredients to keep a favored explanation from collapse. But a theory that has probably passed its must-use-by date will have enough extra bells and whistles to discourage Rube Goldberg from trying to get it to work.
However, there is nothing that says Mother Nature had to be supremely parsimonious. In a complex system like Earth, there can be odd coincidences that are meaningless (like the Moon and Sun sharing the same apparent diameter from Earth’s surface) and outcomes that might be highly improbable (taking over 500 million years to get intelligence after making complex animals with hard parts seems like dawdling, especially when burning most of that time on dinosaurs). Even so, Occam can be a help if used with care.
But lots of times you can face competing hypotheses that lack Occam-style clues. For instance, which is simpler: that post-5 Ma erosion of the High Plains of the U.S. was caused by an eastward tilt, or that this was the product of a changing climate? Both are pretty easy to describe; both have issues. Yet many earth scientists feel pretty comfortable arguing that one is correct; what is the basis of such assurance?
Arguably the most common discriminator used by earth scientists is the principle of least astonishment. What surprises you least feels, in an Occam kind of way, like the interpretation that is most likely. The problem is, we all are astonished differently.
If you are a sedimentologist, you might look at the problem of the High Plains as one of depositing the Ogallala Group in the Miocene as crucial. Could you possibly deposit something like that on a slope like that we have today? This seems so astonishing that if can’t be right; the original slope had to be lower.
But maybe you are a geophysicist looking at the ways to create a tilt about 5 million years ago over something like 1000 km. That looks really hard to do, especially if dynamic topography from flow under the lithosphere is ruled out. It would be astonishing if that happened; it must be that the grade was already there much longer ago.
Skepticism from both geoscientists is warranted; either of these seems really hard to do. Data is gathered by both sets of experts. Margaret McMillan and colleagues measure paleogradients in the Ogallala using a widely applied approach and find there must have been a lot of tilting. Will Levandowski and colleagues (including GG) look at geophysical measurements and find support for the elevations comes from within the crust, where changes over the past 5 million years seem exceptionally implausible.
Could these be resolved? Well, you could posit that prior to 5 Ma there was dynamic subsidence holding the western end down and once that was released, the crustal buoyancy expressed itself. But now Occam detectors are flashing red–this feels ad hoc. Of course, there could be mistakes in the measurements of paleogradient, or in relating seismic wavespeeds to densities–each side has poison darts to shoot at the other side.
What makes this frustrating is what makes this interesting. After all, in the end somebody will be astonished–the earth did something they didn’t expect.
And a funny thing, shoes flip feet in the Sierra, where those studying the sediments argue for no tilting despite deposition at an even steeper grade than modern-day Ogallala, while geophysicists feel they have good evidence for a very recent change in the buoyancy structure of the region.
Are you astonished yet?
Residents of Honolulu were probably looking out their windows if they checked CNN this morning…
If you can’t read the small type…
Honolulu is of course on Oahu, several islands away from the Big Island where the eruption actually is occurring.
While CNN showed off their unusual understanding of geography, the NY Times pushed Earth’s history back to far before the beginning of the universe:
Wow, 202 trillion years ago the Earth wandered somewhere different? What was Earth even doing back then, given there was no universe? [The article correctly talked about 202,500 years].
Imagine, if you will, that a Congressional committee on transportation decides to have a hearing focusing on improving our transportation infrastructure. The session opens with the committee’s chair noting that there is considerable controversy in the engineering community on the use of steel beams in building overpasses, and so we should refrain from building overpasses until the community agrees on the need for steel beams. A highway engineer then testifies that no, there is no such controversy; at most, there are some disagreements on some details about anchoring beams and such not, and regardless of the choices made, new overpasses with steel beams are far better than the overpasses we continue to use today. A committee member then pipes up suggesting that overpasses are collapsing because of the weight of birds’ nests in the nooks and crannies on the overpasses. Nothing is done and roads continue to crumble.
You’d wonder just when Congressmen became such experts in engineering and marvel at their ability to keep anything from being done. And yet hardly anybody bats an eyelash these days when this scenario plays out with the House Committee on Science, Space and Technology’s hearing on “Using technology to address climate change” , where committee chair Lamar Smith added to his already considerable collection of misrepresentations of the science by claiming that humanity’s role in climate change is unknown and that there is “legitimate concern” that climate scientists are cooking their studies to get desired results (as opposed to, say, certain politicians misstating the science to get desired outcomes). Perhaps best of all was the suggestion from Alabama Congressman Mo Brooks, who offered that rocks falling into the ocean could be driving rising sea level.
Well, to be fair, Brooks actually asked about all the material being dumped into the oceans from rivers and such not, which at least isn’t unscientific. But these questions are often posed as though nobody had thought of that (the answer is that of the >3 mm/yr rise we see today, perhaps 0.02 mm/yr is from sedimentation). No doubt we’ll soon get pop quizzes from Congressmen about plate tectonics, glacial rebound (which is a player, but actually dropping sea level at about 0.3 mm/yr), the rise in sea level from more and more boats, etc. Yes, the people whose careers are spent worrying about this stuff have indeed thought about this stuff. We’re still waiting for the day when a Congressman’s question reveals a truth about science previously overlooked by scientists.
What was more disingenuous was Smith’s display of plots of fossil fuel use and sea level rise over time and saying that obviously the rates were so different that a connection was unlikely. (Phillip Duffy’s response kind of missed the point). Um, OK, time for a science experiment at home. Take a pot of water, put it on a gas burner. Turn on the burner–what is the rate of use of fuel? Pretty high right away, no? How about the temperature of the water? Um, still pretty cold, no? If you plotted them up, you’d probably find that while the rate of gas usage might be constant, the temperature of the water in the pot gradually increased. Obviously these are unrelated since they look different. (And the real world version involves 2 more levels of integration–first as CO2 levels increase, which is an integral of the fossil fuel use rate, then the change in heat in the atmosphere and oceans, which has both some integration and lag time, and finally the connection of that to sea level rise similarly has a lag and integration of sorts as thermal expansion is aided by melting ice. Yes, the curves will look different).
There are precisely two explanations for the kinds of misrepresentation engaged in by several members of Congress. Either they are stupid or they are crooked. GG actually doubts stupid; getting elected and managing a staff and doing all the fund raising and everything else requires some basic level of competence. This leaves crooked, and by that GG means that they need a certain result for reasons not being shared with the public and so seek to obfuscate. No doubt all or nearly all politicians make public pronouncements they know to be false as a means of appealing to their constituents, but one has to wonder at this point who this charade is for when significant majorities of Americans think the government is doing too little to deal with climate change.
GG has from time to time wandered on a bit about some of the contradictions surrounding public lands (as a geoscientist, GG has spent a fair bit of time on said lands). So three articles in the latest issue of High Country News (their “Outdoors and travel special issue”) caught his eye as they threw light on three different aspects of our varying and changing views of wild lands. In a sense, all three pieces reflect views that would probably have distressed John Muir and other 19th century celebrators of the wild.
The first (and cover) story documents the growing disconnect between realities: that on the ground, and those developed in social media. The story recounts the five 2017 deaths on Capitol Peak in the Colorado Rockies, focusing on one in particular where the temptation from social media wore down any resistance to doing something very risky. In a real sense, this documents the continuing replacement of wilderness as a place for reflection and understanding of our place in the big wide world with a handy backdrop for our social media musings. This has made the great outdoors nothing more than a different edgy stage for our narcissistic self-promotion (“Look at what I did!”). Unfortunately the real world has taken little notice, and so bad injuries and deaths can pile up as the temptation of one-upmanship continues. Although the piece lays the blame on our obsession with social media, it is worth pointing out that this has gone on far longer. Once cell phones started getting signals in wilderness areas, people would just assume they could march out and get into any fix they liked and they would be rescued.
The second deals with another aspect of the wilderness as personal gym mentality, suggesting that outdoor equipment companies might not have the best interests of the land in mind when they advocate for preserving landscapes. In particular, the author, Ethan Linck, points out that these companies are far more interested in saving places with dramatic and photogenic places than ecologically more valuable lands. He buttresses this with some insights from research showing that outdoor recreating is only weakly related to broader environmental concerns. Thus people who recreate outdoors can be passionate about preserving access to the lands they use but are far less likely to care about other places and other threats. The author goes on to note how older distinctions between consumptive and appreciative uses of wild lands are increasingly confused. The result is something of a fraying of the coalitions that advocated for Wilderness Areas over the past 50 years; deferring to corporations to take up the slack might not be the best way to preserve what should be preserved. At the same time, the way companies glorify wild lands in advertisements acts in a way similar to social media trivialization of these places.
The last is more of a current news item: legislation in Congress would remove restrictions on bikes in Wilderness Areas (along with motorized wheelchairs and a few other wheeled vehicles). This bill splinters the mountain biking community: the Sustainable Trails Coalition supports the bill while the International Mountain Biking Association opposes it. This is again moving to further trivialize the wild, to say it is really only useful as a free gym. While there are legitimate complaints from the biking community about how some Wilderness areas are drawn, there are some good reasons for excluding bikes from Wilderness.
All three stories point to nature becoming little more than a scenic backdrop for feats of derring-do, for getting pumped up, for setting records and personal bests. And if that is all we want, that is all we’ll save, and we’ll lose a lot more than we’ll know.
(Updated on 5/15 with links to the HCN stories now online)
Is the deluge of scientific publications taking us closer to unraveling unanswered questions? Or is it adding to the noise that makes identifying the really significant publications difficult?
One guess as to the answer.
We’ve been in this neighborhood before a few times but it bears repeating. Simply making the reward structure in science revolve around numbers of papers and their derivatives (like h-indices) is just plain bad. As the post reminds us, it burdens reviewers, it tempts shingling, it encourages sloppiness if not outright dishonesty, it clutters the literature, maybe even deletes all your email. Maybe we should rename the process “publish and perish.”