One of the cross-cutting themes in condensed matter physics is that simple interactions between particles lead to complex behavior when many particles are combined together. Many of the research projects in the group address examples of this emergent behavior. Topics include why friction is proportional to load, why adhesives are thousands of times harder to break than thermodynamic estimates, why entropic forces appear to describe polymer mechanics at zero temperature, why virus capsids seem to deform like springs, what leads to power law distributions of avalanches in magnetic domain wall motion and along earthquake faults, how continuum mechanics breaks down at atomic scales and what new physics becomes important at the nanoscale. Papers on these areas are at www.pha.jhu.edu/~mr/papers.html and talks at www.pha.jhu.edu/~mr/talks.htm. The links above connect to separate pages on different areas.