To try everything Brilliant has to offer—free—for a full 30 days, visit http://brilliant.org/ChronovaEngineering/ . The first 200 of you will get 20% off Brilliant’s annual premium subscription. This video was sponsored by Brilliant. In this video, we investigate how sharp different edges are by attempting to split a single hair. The results from this are unexpected, so we try to understand the problem better by building a sharpness tester and even measuring the edge with an atomic force microscope.