Problems With the Canonical Giant-Impact Model of Moon Evolution

Lunar-Origin Studies Are “In Flux”

The problem with evolutionary theories is not that they are impossible—any theory, no matter how bad it is, if held with sufficient conviction can be adorned with enough epicycles to explain the data and avoid outright impossibility. And evolutionists certainly do have the needed conviction. For evolutionists, their theory simply cannot be false. That option is not on the table and they will do whatever it takes to avoid it, including blackballing scientists, falsely claiming the theory to be a scientific fact, misrepresenting the science in courts and in textbooks, contriving false histories, and so forth. And so while evolutionary theories can never be outright falsified, they are improbable. This can be seen both (i) by comparing the theory with the evidence and (ii) by all those epicycles which evolutionists must use to patch up their theories. The many patches added to evolutionary theories result in high complexity and loss of parsimony. One example that Robin Canup recently discussed is the origin of the Earth-Moon system.

Modern evolutionary theories attempting to explain the Earth-Moon system go back to the late nineteenth century when George Darwin, son of Charles, proposed that the Moon was made of materials ejected from the Earth by tidal instabilities. This fission hypothesis was followed by capture, co-accretion and impact hypotheses as well. Various types of hypotheses have been considered because none of them work very well. For no single hypothesis has been able to account for the various evidences, such as the mass of the Moon, the angular momentum of the system, and the high similarity between the chemical compositions of Moon rocks and the Earth crust.

In recent years the giant-impact hypothesis has been able to explain the size of the Moon and the system’s angular momentum, but not the Moon rock’s composition. Of course explanatory mechanisms can always be contrived. For example, perhaps the impacter just happened to have the same chemical composition as the Earth upper layers. But that would be “extremely improbable” explains Canup, as such similarity is not typical within the solar system.

There are other possible explanatory mechanisms as well, but inevitably, as with biological evolutionary theories, they complicate the theory and rely on serendipity and coincidence. As Canup explains:

It remains troubling that all of the current impact models invoke a process after the impact to effectively erase a primary outcome of the event — either by changing the disk's composition through mixing for the canonical impact, or by changing Earth's spin rate for the high-angular-momentum narratives.

Sequences of events do occur in nature, and yet we strive to avoid such complexity in our models. We seek the simplest possible solution, as a matter of scientific aesthetics and because simple solutions are often more probable. As the number of steps increases, the likelihood of a particular sequence decreases. Current impact models are more complex and seem less probable than the original giant-impact concept.

That, in a nutshell, is the story of evolution. Initially simple theories, which far exceed the scientific knowledge of the day, are constructed from a metaphysical commitment to naturalism. These theories are more mythological than scientific and they inevitably fail badly as science progresses. The commitment to naturalism, however, trumps all else and the theory’s initial parsimony easily gives way to incredible complexities.

The failure of evolution lies not in its falsification—an impossibly high bar evolutionists routinely erect to protect their theory—but in its failed predictions, improbability and resulting complexity and loss of parsimony.

Canup’s acknowledgment of the problem is a rare exception to the rule of declaring evolution to be a scientific fact regardless of the failures.