Da Vinci Was Wrong About Friction, Says Earthquake Study

Common understanding of friction, a subject that dates back to classical thinkers like Leonardo da Vinci, might not be as accurate as once thought. According to a recent study of earthquake models, friction and fraction - two largely separate phenomena - might be far more closely interrelated than classical minds assumed.

Hundreds of years ago, classical thinker and inventor Leonardo da Vinci first described "dry friction," detailing the various forces that come into play when two rough blocks slide over one another. This concept was later expanded and refined by modern minds, but the basic principles remained the same. These same principles were also seen as largely different than fracture - the phenomena involved in the breaking of a solid surface.

However, according to a new study published in the journal Nature, friction and fracture may be more similar than previously thought.

In an analysis of lab-controlled "earthquakes" using rough polymer blocks, author Ilya Sventlizky and co-author Jay Fineberg determined that the onset of friction can only occur following a remarkably fracture-like process.

According to the study, the results support a theory of "crack propoagation" - where the forces that exist along the edge of a crack between two objects must become highly magnified before friction plays a role, even if the forces that prompt the initial linear fracture are remarkably small.

"The insights gained from our study provide a new paradigm for understanding friction and give us a new, fundamental description of the mechanics and behavior that drive earthquakes, the sliding of two tectonic blocks within natural faults," Fineberg said in a statement. "In this way, we can now understand important processes that are generally hidden kilometers beneath the earth's surface."

An expert assessment, published in Nature Physics, best establishes the importance of this discovery, explaining that if the phenomenon behind the initial "slip" between two dry bodies can be measured much like linear fracture mechanics are, an understanding of plate tectonics can potentially be simplified.