A colloquium should be at least in part accessible to the entire audience, while at the same time everyone should learn something new and fascinating related to physics. The audience consists of members of the Physics and Astronomy department, including faculty (theorists and experimentalists), postdocs, graduate students, and sometimes even advanced undergraduates. Hence our key guideline is that the talk should be accessible to first-year graduate students not in the speaker's subfield, while still interesting to seasoned experts within the subfield. Crafting such a talk is verily challenging; here we offer more detailed advice on how to prepare and structure such a talk.
The preparation required to do this well is quite different than it is for a talk for a specialized audience. Subfield jargon needs to be limited, and defined when introduced. The motivation for the work you will be presenting needs to be very clearly presented in a manner understandable by the entire audience. Motivation and background material might take an entire third or half of the talk. The bulk of the talk should still be accessible by our first-year graduate students. It is acceptable to be speaking to a narrower audience in the final third, so that there is something in the talk that your fellow experts might learn from, although a concluding summary should again be broadly accessible.
It might be helpful, as you prepare your talk, to be trying to see it through the eyes of a colleague outside your field. Ask yourself what you want them to take away from your talk, and whether it is actually achievable. Consider whether your talk would benefit from fewer takeaways, with each one communicated more clearly.
Thank you for taking the extra time necessary to prepare a presentation which communicates well to this broad audience. By doing so, it will allow us all to enjoy your ideas, insights, and results. We hope you will find that rewarding!
