Darn you Stephen :-) You got me hooked on this thing!
B4 is "Heat" (1995 Pacino/DeNiro) or "The Heat"
This one took me hours of research. I'm not smart enough to recognize the "Heat Equation" on sight or understand it. But I knew it was a partial derivitive of something with respect to time. Poked around for a while to figure out that the upside down triangle is a "del" or a "nabla" used as a vector calculus operator. Ok. At this point I still didn't know ANYTHING. But further research uncovered that a del-squared is the Laplace Operator, which is used all over the place from Schrödinger equation to Poisson's equations to the wave equation to the HEAT equation. But I couldn't just accept that and run, so I had to look into the heat equation and found that there are a jillion representations for it. But in the case of heat propogating in a homogonous medium in 3D space, you the below equation: which is mathematically equivemant to B4.
What's really annoying is that as an undergrad, eons ago, I actually studied a lot of that kind of math... and now it is all just greek to me.