Reining In the Expanding Earth
Although the Expanding Earth may seem like a silly conjecture, it was actually one of the leading geophysical models quite recently.
If you pick up a globe and study the way distant shorelines would seem to fit nicely if they were somehow brought together, it might not seem all that silly to allow for the possibility that the Earth has changed its size — significantly. Imagine that globe shrinking in your hands, but the familiar continents staying the same size. Closer and closer they would get to one another, as we went backwards in some hypothetical timeline — until they all slotted neatly together: Antarctica nestled between Africa, Australia, and India; Greenland filling the space between North America and Eurasia; until you held in your hands a solid rock ball.
Today, of course, the notion that the Earth got into its present configuration by expanding from a smaller size seems silly. It seems to belong with the Flat Earthers and the Hollow Earthers, and all the other geophysical crackpots. But how would you react if I told you that expansionism was actually a mainstream theory, and not all that long ago? And, further, if I told you that contractionism — its opposite model — enjoyed a similar mainstream status? As recently as 1900, contractionism was in fact the leading model of the Earth's geodynamics, with expansionism a close second. Mobilism — an umbrella term for theories like continental drift, and eventually, plate tectonics — was considered the realm of crackpots. So it turns out that a skeptical look at the Expanding Earth theory (and as we'll see, in its day it did indeed qualify as a theory) is not just a case of poking fun at nutty YouTube channels.
In recent years, one of the most visible proponents of the Expanding Earth has been the famous comic book artist Neal Adams, who posted a YouTube animation way back in 2007 explaining the idea. Adams died in 2022, but that video has had millions of views and was influential in reviving the Expanding Earth concept among today's conspiracy theory and alternative history crowd — the type who will believe anything that's on Ancient Aliens or on YouTube so long as it contradicts mainstream science. This is unfortunate, and it's an undeserved legacy for Adams; he had to endure 20 years of being called a crackpot, for nothing worse than adhering to an old idea that, although currently thoroughly disproven, had been mainstream in its day when he had been a young man. He made a series of more than twenty such videos, and they are generally in line with what was a leading geophysical theory for nearly a century. Where Adams breaks with the traditional theory is in the mechanism for the expansion of the Earth. In his modern version, it was the creation of new matter at the quantum level, a notion that science was just beginning to be aware of around the time that plate tectonics took over as the dominant geophysical model, and the Expanding Earth was discarded.
We can get a fair snapshot of the state of geophysical models right around the turn of the 20th century. In the late 1800s and early 1900s, science was still groping for explanations of why the continents appear to fit together; how various mountain ranges were formed; and what forces drove these mechanisms. Competing models included the Earth contracting as it cooled. They included the Earth expanding via various mechanisms. They also included various models for continents moving around on a constant-sized Earth.
Contractionism, believe it or not, had been the leading geophysical model worldwide at that time. This theory holds that as the early Earth cooled, it contracted, as molten rock and most other substances do when they cool. Geophysicists believed that as the Earth shrank, its rigid crust buckled, and this buckling was responsible for mountain ranges and many other features. It was never an ignorant or crackpot theory. Contractional deformation remains today our explanation for what happened on the planet Mercury which is crossed with thrust faults; models suggest that the diameter of Mercury has shrunk by some 7 km. Even on Earth's Moon we find features that are believed to be the result of thermal buckling, both expansive and contractive. And so, by no means was the Contracting Earth theory wacky or unscientific. There are plenty of features on Earth that could aptly be alternately explained by contraction; it was only later when more geophysical knowledge came in that the model was found to no longer be compatible. Among other things, radioactivity was discovered, with the result being that the Earth would continuously remain heated from within, thus preventing thermal contraction.
Continental drift was an idea that arose about this time, which was an incomplete hypothesis. It recognized that the continents moved around, but did not include a mechanism. This was the brainchild of Alfred Wegener, arguably the father of modern science-based geology. Based on multiple lines of evidence, he first published his hypothesis of continental drift in 1912, but he also recognized its weaknesses. The idea, from Wegener and others before him, was that the continents — not continental plates which were unknown at the time, but the land masses themselves — floated slowly around the Earth into their current positions. The idea had been around for some 300 years but had never gained traction. Following Wegener's publication, others proposed mantle convection as a possible mechanism, and more geophysicists signed onto the model.
But not all of them. A number of Earth's features could be explained equally well by the planet having expanded, breaking apart the supercontinent Pangea and placing the continents into their current positions. As late as 1975, a paper by the respected Australian geologist S. Warren Carey found flaws — to him, fatal flaws — with plate tectonics, by then the widely accepted standard model. He discussed a number of mechanisms — of varying plausibility — which would make it possible for the Earth to expand. Among them:
Although firmly an expansionist — "Empirically," he said, "I am satisfied that the Earth is expanding" — Carey maintained a sufficiently scientific perspective that he still listed the types of evidence that would change his mind.
And so through the first half of the 20th century, geophysicists were divided into the camps of expansionists, contractionists, and mobilists — those who accepted Wegener's still-controversial continental drift. But then things changed.
Around the time of World War II, evidence emerged that mobilism was almost certainly correct, but not quite the way that Wegener had guessed. Rather than the continents moving around, plowing through the oceans, it became apparent that the entire Earth's surface was made of a series of plates which moved past, over, and under one another. Plate tectonics was suggested by three primary lines of new evidence:
And so, unambiguously, plate tectonics was proven to be the correct geophysical model. Almost all the expansionists and contractionists came over to the side of the newly reformed mobilists. But not all of them. A few, like Carey, remained for a time. Today we have a whole new generation of evidence that Carey, had he continued his working life to see it (he died in 2002, but had retired from active research long before), probably would have embraced. We now have strong empirical evidence that the size of the Earth is constant, at least to within statistical significance.
Today the world's scientists have the International Terrestrial Reference Frame, first established in 1988, and which today maintains a geodesic model of the Earth accurate to within one centimeter. It incorporates four main types of data:
Yet, while no scientific question remains today, expansionism has managed to survive; mainly among the Internet conspiracy theory crowd, and driven in no small part by the license given to them by Neal Adams and his adherence to the old theories. Today's iteration is supported not by the kind of geological data that early 20th century expansionists studied and which Adams had embraced, but by exotic buzzwords of the type beloved by undereducated conspiracy theorists. No matter what YouTube channel you might tune into to get pitched the "truth" about the Expanding Earth, the fact remains that the International Terrestrial Reference Frame leaves no room for esoterica.
So continue to enjoy your globe, and to study the way the continents were once arranged. But do not fall into the YouTube conspiracy trap of rejecting knowledge and evidence in favor of conspiracy mongering. How we know what we know is always the most exciting part, and it's nearly always absent in the alternative science crowd.
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