Physicists study mechanics of 'crackling'

January 27, 2011 By Anne Ju

( -- Everywhere around us, things "crackle" -- from Rice Krispies in a puddle of milk, to crumpled pieces of paper, to the Earth's crust from earthquakes. Physics is helping us understand what this familiar noise is and how it happens.

A study led by postdoctoral associate Stefanos Papanikolaou and Professor of Physics James Sethna provides new insights into the patterns created when things crackle. For the experiments, Sethna's colleagues in Italy and Brazil used magnets, which the researchers call an "excellent playground" for studying such phenomena. The work was published online Jan. 23 in the journal .

Crumple a piece of paper and watch small areas bend and crease abruptly. In the same way, as a magnetic front moves forward, it advances in sharp jumps. As it grows, the magnetized region gets stuck on impurities and imperfections in the material, jumping from one bunch of dirt and getting stuck on another. Physicists call these "crackles" avalanches.

The scientists listened to this magnetic crackling in a one micron-thick -- so thin that they introduced new methods to extract the crackles from the noisy data. As was predicted by theory, they saw that the big avalanches were scaled-up versions of the small ones, as well as mergers of the small ones.

Physicists use this so-called scale invariance to explain the relative number of avalanches with large and small sizes, or short and long durations, and other properties. For example, there are many more small earthquakes than larger ones, which is a "power law" distribution -- that is, the number of earthquakes is given by a power of their size. The Cornell researchers were able to go beyond these power laws to predict the avalanches' average shapes, and also, the shapes of their size and duration distributions.

The researchers' success in describing avalanches in thin magnets gives hope for understanding the larger phenomena that follow these self-similar patterns -- for example, the way the Earth cracks during an . Earthquakes are avalanches, too -- the Earth's crackling response to moving tectonic plates. The scaling that explains how magnets crackle and how paper crunches may be useful in predicting how earthquakes spread.

"We don't know how to predict when earthquakes will happen -- which is what people want -- but we are gaining real control about what avalanches look like in magnets -- their shapes and sizes and speeds. Magnets are a place to do experiments to understand earthquakes," Sethna said.

The work was done in Cornell's Laboratory for Atomic and Solid State Physics and was supported by the National Research Council of Italy and the Department of Energy.

Explore further: A new discovery helps us to understand the complex nature of earthquakes

Related Stories

Ill. earthquake a wake-up call

April 20, 2008

A U.S. seismologist said the earthquake that jolted the Midwest Friday is a reminder of the risks seismic events pose outside familiar quake areas.

New way to monitor faults may help predict earthquakes

October 1, 2009

Scientists at the Carnegie Institution have found a way to monitor the strength of geologic faults deep in the Earth. This finding could prove to be a boon for earthquake prediction by pinpointing those faults that are likely ...

Earthquakes actually aftershocks of 19th century quakes

November 4, 2009

( -- When small earthquakes shake the central U.S., citizens often fear the rumbles are signs a big earthquake is coming. Fortunately, new research instead shows that most of these earthquakes are aftershocks ...

Recommended for you

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...

Exploring the physics of a chocolate fountain

November 24, 2015

A mathematics student has worked out the secrets of how chocolate behaves in a chocolate fountain, answering the age-old question of why the falling 'curtain' of chocolate surprisingly pulls inwards rather than going straight ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.