September 2 2008

FerroFluids: Physics is Beautiful

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Immanuel Kant, in 1790, described beauty as 'sensory, emotional, and intellectual,' a synthesis of data which we as humans process when evaluating objects. More recently Abraham Moles, Frieder Nake and Jurgen Schmidhuber, leaders in the field of aesthetics and information theory, described beauty as 'the option with the shortest description, given the observer's previous knowledge and method for encoding data.' We as humans often find forms in nature which we find pleasing and wish to share. Whether it is a vista or microscopic, the structures nature has built are often times inherently beautiful to our eyes for probably very complex reasons alluded to by philosophers and scientists throughout the ages.

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Ferrofluids are one of my favorite examples of beauty and aesthetics occurring spontaneously as a simple reaction between elements and forces of nature. A fluid, formless and simple, turns instantly into a sculpture, structural and complex with little more than the application of a magnetic field. The phenomena is used in many industrial applications including the seal on the hard drive spinning in your computer and has recently been used to create abstract art. Ferrofluid_Image 02

Ferrofluids are liquid mixtures of surfactant coated magnetic nanoparticles in a carrier fluid which are easily susceptible to magnetic fields. The compounds themselves contain some iron (hence ferrous, ferrum, meaning iron in latin) but the liquid mixture is not magnetic. Brownian motion applies between particles and means that the mixture does not settle under typical conditions.

Ferrofluid_Image 03_by Flickr AMagill

The fluids react in predictable but astounding ways in the presence of even the smallest magnetic field. The only criteria is that the field be strong enough to overcome surface and gravitational forces on the fluid. This effect is called the 'normal-field instability' and results in a regular pattern of corrugations on the surface of the fluid. Amplitude and frequency depend on the strength of the magnetic field and it is important to note that the fluid returns to a completely liquid state upon the removal of the magnetic field.

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Below is an example of artwork created by carefully and selectively applying a magnetic field to a ferrofluid by artists Sachiko Kodama and Yasushi Miyajima.

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