Does light (like heat) seep and weaken? [more inside]
posted by Pennyblack on Feb 18, 2009 - 5 answers

Why do some social web platforms catch-on (e.g. Twitter, Facebook, Wikipedia) while countless others don't? [more inside]
posted by GIMG on Feb 13, 2009 - 15 answers

Yeah, this could be the lamest applied math/engineering question ever - is there a good resource that can show me how to solve the heat equation in two (or more) spatial coordinates, with a source? [more inside]
posted by universal_qlc on Aug 8, 2007 - 12 answers

So sharks can smell one part blood in one million parts seawater. How? I understand that the blood would diffuse in water, but wouldn't at least a particle of the blood have to come into contact with the shark? Does diffusion happen that fast?
posted by Coffeemate on Jul 12, 2004 - 11 answers