In this paper we present an alternative perspective to physics expertise research. Using Lave and Wenger's theoretical perspective of Legitimate Peripheral Participation  as a guide to understanding expertise development, we redefine expertise from the perspective of physicists. We analyze data from an ethnographic, qualitative study of a physics research group and draw data from multiple sources to triangulate a definition of expert. Results show that a very critical part of becoming a physics expert in this physics research group is communicating one's scientific ideas through writing. Students perceive scientific writing as an important aspect of participating in the research group and it is a significant discussion point in the research meetings. Thus, it appears that learning to write a scientific paper is a process congruent to developing physics expertise. © 2012 American Institute of Physics.