Warm-up to the Big Explanation: I have been trying to explain what I do and why I am excited about it to various friends of mine, more than a few outside of the field, and most outside physics. It's good practice for the inevitable family occasions. The problem is that my field is in an awkward moment: we have an enormous and varied data set on collisions of really complicated objects (to exponentiate a cliche: think of a swiss watch, made of other swiss watch), which shows "interesting" features. By this I (and in some cases only I) mean that the data is somehow "simple" ("suprisingly", "shockingly", "intriguingly" so). But "simple" is a term often confused with "trivial" so this assessment almost always gets a bad name. Rather, the features of our collisions are such that it appears that the details of the swiss watches are lost in a cloud of smoke, in some sense, which sounds like a let-down, but whoever said that understanding clouds dynamically was "trivial"?
Some people are claiming that we are making the most perfect fluid imaginable, a claim with which I am sympathetic. But I haven't even explained what the fluid is made of (or what a fluid is in the first place, but that's an easier business once you know what "it" "is").
The answer is the question we address at RHIC, the Relativistic Heavy Ion Collider, at Brookhaven. We are a real "atom smasher" facility, colliding gold atoms (without their accompanying cloud of orbiting electrons) at the highest energy available until 2008, when CERN will try and steal RHIC's thunder (again -- last time was 1994, when I worked there!). The reason we do this has two answers, the "official" one for the field, and the "emergent" one, which may or may not map onto the official one in a straightforward way.
In the spirit of David Foster Wallace, whose book "Everything and More" I've been plowing through slowly but surely, I'm going to embark on several digressions, less as an attempt to ape someone whose style and execution I admire a lot, but out of sheer necessity. I've been struggling with this since college: while the most elegant arguments are pure linear, I continue to find the whole Procrustean bed aspect of this process frustrating to say the least. The more complete answers require multiple iterations from the surface to the depths. I've been skimming the surface so far, and it may just be time to dive. More next time.