Live jazz music crashes through the dark bar as my friend and I discuss what it means to be 'interdisciplinary'. My beer-loosened words are barely audible over the music.

First, I say, we must define a discipline. I describe my experience as a postdoc. In my first position, I did experimental work in single-molecule biophysics, manipulating muscle proteins with laser tweezers. Perhaps a dozen labs use this method; they have a vocabulary and notation convention that define the discipline.

My current position, I contend, is interdisciplinary. I use mathematical and mechanical models to understand biology. Some of this work addresses the same questions as my previous experimental work. However, for my current work, no single community of researchers exists. One community understands our mathematical methods but not the biological systems; another is familiar with the biology but not the maths.

Conducting research that spans the expertise of two or more groups, yet is understandable to each, presents a challenge. Because researchers are often experts in a single discipline, reviewing interdisciplinary papers can be difficult. Yet it presents the fantastic opportunity to start a new discipline.

As the music swallows my final words, I look across the table at my friend, a new graduate student, and doubt if I have been much help. I wonder how she will define interdisciplinary when she becomes a postdoc.