Salvador Cordova gives us a rundown of two basic models of physics being being explored by YECs. One starts with electrodynamics and the other starts with Einstein's special relativity. Both groups presented papers at ICC. I'm not all that knowledgeable in physics, but it looks like an interesting set of propositions either way. I'm reading through Hartnett's Starlight, Time, and the New Physics. It's interesting, but I don't have the background to make a judgment.
Anyway, the interest of physics for YEC'ers is twofold: 1) some YEC's are physicists, and thus they simply have an interest in both areas. 2) Physics is usually what is used to derive cosmologies, and therefore, the goal is to derive a YEC cosmology from the laws of physics.
Interestingly, AiG's Jason Lisle doesn't opt for any of these extensions to physics, but instead opts for an old universe in which the light from the distant stars all reach Earth on day 4 - they were created in such a pattern so that the light from all of them would reach Earth at the appropriate time.