Giovedi' 14 Aprile, ore 16:00 (Aula Caldirola)
Speaker: Andrea Gambassi (Sissa, Trieste)
Title: The critical Casimir effect: thermal fluctuations in action.
Abstract: In 1948, Hendrik Casimir predicted that two uncharged
conducting surfaces in vacuum attract each other due to the quantum
fluctuations of the electromagnetic field which are spatially confined
by these surfaces. The classical analogue of this effect originates from the
confinement of thermal fluctuations in fluids near continuous phase
transitions, such as the demixing of a mixture of two liquids or the
normal-superfluid transition in 4He. Early indirect experimental
evidence of the force of these fluctuations - the so-called critical
Casimir force - were provided by detailed studies of complete wetting
films.
Thirty years after its first theoretical investigation by Michael
Fisher and Pierre-Gilles de Gennes in 1978, the critical Casimir force
has now been measured directly at the sub-micrometer scale by monitoring
the Brownian motion of a colloidal particle close to a surface, both
immersed in a near-critical liquid mixture.
I will present recent advances in the theoretical and experimental study
of the universal properties of this novel fluctuation-induced force,
discussing possible relevant applications for manipulating soft matter
systems.