Physical Society Colloquium

Interview for Faculty Position

Force generation due to fluctuations of media and boundaries

Ramin Golestanian

IASBS

In a fluctuating medium of whether quantum, thermal, or non-thermal origins, an interaction is induced between external objects that modify the fluctuations. These interactions can appear in a vast variety of systems, leading to a plethora of interesting phenomena. Notable examples of these include: (1) like-charge attraction in the presence of multivalent counterions, (2) Ludwig-Soret effect in charged colloids, (3) mass renormalization of moving defects in a phononic background and moving metallic objects in electromagnetic quantum vacuum, and (4) dissipation due to motion-induced radiation. Another related class of problems corresponds to stirring the media by dynamic deformations of the embedded bodies and benefiting from the back-reaction of the stirred media for force generation, such as force generation in swimming. The fluctuation-induced forces are statistical in nature, and this could make their measurement very difficult, because the actual value of the force might deviate most of the time from the predicted average value.