I wanted to highlight some recent experiments conducted at the Jefferson Lab in Virginia. The group measured the interactions of electrons with quarks, and was able to measure the weak nuclear interaction between these particles with greater precision than any previous experiments. (I'll link to the journal article as soon as it is published.)
They quantified the breaking of the mirror (P) symmetry of the weak nuclear force. Though, it should be point out that this type of measurement is not new. It has been know for a long time that the weak nuclear force violations P, as well as T & CP symmetry.
My main point in highlighting this research is that this measurement was much more precise than previous measurements and that this measurement is in agreement with the Standard Model of physics. (i.e. most data for the Standard Model and more data that reduces the likelihood that there is Beyond Standard Model Physics at the <10 p="" scale.="" tev="">
My secondary goal in highlighting this research is to highlight that the weak nuclear force is present in collisions between electrons and quark, which means that it's present any time molecules collide with sufficient velocity. This in turn means that the weak nuclear force is most likely the cause of the arrow of time.
Notice that we never see an arrow of time when there's only Boson particles or when Fermi particles are interacting only via Gravity, E&M or the Strong Nuclear Force.
(Try determining which way a movie is running for the following phenomena: superconductivity, superfluid helium, photons travelling in the vacuum of space, or planets orbiting a star.)
The arrow time only exists when there are Fermions interacting via the weak nuclear force.
As such, it's important for us to recognize that Boltzmann's assumption of molecular chaos is not required in order to obtain time-asymmetric equations of motion. You just need to include the weak nuclear force (which occurs only when Fermions collide with sufficient energy.)
I also wanted to let readers know that I'm working on a Socrates dialogue between a defender of Boltzmann's molecular chaos assumption and a defender of the theory that the weak nuclear force is the cause of the arrow of time. I'm hoping that, after reading this dialogue, one will be able to see the problems with the assuming that the reason for the arrow of time is that there is molecular chaos (i.e. randomization of velocities after collisions.) This assumption is quite useful for most problem of engineering interest; however, it's doesn't actual teach us what is the real cause of the arrow of time. (And therefore needs to be scrapped and replaced.)
The real cause of the (one and only) arrow of time is one time asymmetric term that shows up in the weak nuclear force. This means that the real way to determine rate-based coefficients (such as diffusivity, thermal conductivity, and electrical conductivity) is to include the weak-nuclear force into computer simulations of molecular models. Assuming molecule chaos gets us pretty close to the right answer, but it's likely that there are some cases where we can do a better job in predicting transfer coefficients using first-principles than in making Boltzmann's assumption of molecular chaos.10>