Transient Fluctuation-Induced Force
Active matter? Some examples:
Self-propelled colloidal particles Shaken Grains
Are there long-ranged fluctuation-induced forces in active matter?
"Fluctuation-Induced Casimir Forces in Granular Fluids,"
C. Cattuto, R. Brito, U.M.B. Marconi, F. Nori, and R. Soto, Phys. Rev. Lett. 96, 178001 (2006)
"Nonadditivity of Fluctuation-Induced Forces in Fluidized Granular Media,"
M.R. Shaebani1, J. Sarabadani, and D.E. Wolf, Phys. Rev. Lett. 108, 198001 (2012)
"Casimir effect in active matter systems,"
D. Ray, C. Reichhardt, and C.J. Olson Reichhardt, Phys. Rev. E 90, 013019 (2014)
The answer is negative: No long-ranged correlations and no long-ranged interactions in steady state.
Agitating active matter from rest:
Fluctuations of the conserved density field satisfy (model B):C.M. Rohwer, M. Kardar and Matthias Krüger, Phys. Rev. Lett. 188, 015702 (2017)
Resulting steady state is trivial
What happens when the level of activity/noise is suddently changed (quench)?
"Out of equilibrium behavior of Casimir-type fluctuation-induced forces for free classical fields,"
D. Dean and A. Gopinathan, Phys. Rev. E 81, 041126 (2010)
Transient fluctuation-induced force between plates:
Transient fluctuation-induced force between two inclusions:
Conserved density leads to transient long-ranged force. (How "universal" is this result?)