A fine if somewhat intermittent tradition hereabouts has been the offering of high-concept Halloween costumes for people interested in physics, surfacing in 2010, 2012, and 2013. I'm a little too fried right now to do anything all that deep, but I'll try to offer a few suggestions; see also these particle-physics suggestions from Symmetry magazine, who have an art staff to make animated GIFs of their ideas.
Sexy Tycho Brahe: Ruffled collar, magnificent mustache, a little gold paint on your nose. Critically important that you remember to go to the bathroom beforehand, though-- it's going to be a long party.
The Principle of Least Action: Dress like Pierre de Fermat, and remain perfectly still unless you have somewhere to go. When moving from one point to another, carefully plot out the shortest possible path, and sprint along it as fast as you can.
The Holographic Principle: Stick very close to the walls of the room, but watch everything carefully, so as to ensure you contain all of the information about what's happening in the interior of the party.
Sexy Dmitrii Mendeleev: Dress like Radagast in the Hobbit movies. Try to get the other guests to line up in order of weight.
Particle-Wave Duality: When nobody's looking at you, go from place to place in the most wave-like manner possible, say by doing the worm. If you catch anybody looking, stop immediately and walk like a normal person.
The Equivalence Principle: Climb on top of some tall object, jump off, and loudly insist that gravity has stopped working as you fall.
And that's about enough of that for this year. Feel free to throw out your own high-concept costume ideas in the comments.
Currently working on the Theory of Cosmic Inflation costume. I plan on eating something 7/1000ths of my body volume about every 15 minutes during the course of the party to match the rate of cosmic inflation if it were slowed down by a factor of one in a hundred million trillion trillion trillion.