Thursday, August 26, 2010

You Cannot Change the Laws of Physics, Captain

Brooks Sports is advertising its new cushioning system by highlighting its viscoelastic properties.  The new system (called DNA [1]) uses a "highly-viscous non-Newtonian fluid."  The shock absorber uses a semi-liquid filling instead of a semi-solid filling.  The company blog interviews a material engineer who talks a little about basic non-Newtonian behavior.  He uses ketchup as an example.  So far, so good.

The web page that discusses the technology (link here) does have a mistake.  In the video at the bottom of the page, the material engineer states that a "non-Newtonian fluid does not obey the laws of physics." [2,3]

It is precisely because a non-Newtonian fluid obeys the laws of physics that we observe unusual physical behavior like shear-thinning or shear-thickening.  A fluid that did not obey the laws of physics would defy gravity, or it would spontaneously separate into its individual elemental components.  

[1]  I could not find an explanation for this abbreviation.
[2]  Brooks is traveling the country with a vat of cornstarch and water advertising the new technology.  For other videos of shear-thickening behavior, go here.
[3]  I left a comment on the Brooks blog, but either it was not approved, or was removed.


  1. "non-Newtonian fluid does not obey the laws of physics". Wowwee! Just wait until I start telling my bosses I'm so good that I don't have to obey the laws of physics when I'm working with non-Newtonians.

    But now that puts me on the horns of a dilemma. In the past, I've always stated that I kept a mess on my desk because if I removed the mess, then I would be be creating a vacuum and nature abhors a vacuum and therefore I had to follow the laws of physics and not have a clean desk. So now what do I do?

  2. non-Newtonian fluid does not obey the USUAL laws of physics, those usual laws one learns at primary school.