Transient Fluctuation-Induced Force

red ball Are there long-ranged fluctuation-induced forces in active matter?

yellow ball "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)

yellow ball "Nonadditivity of Fluctuation-Induced Forces in Fluidized Granular Media,"

M.R. Shaebani1, J. Sarabadani, and D.E. Wolf, Phys. Rev. Lett. 108, 198001 (2012)

yellow ball "Casimir effect in actice mtter systems,"

D. Ray, C. Reichhardt, and C.J. Olson Reichhardt, Phys. Rev. E 90, 013019 (2014)

yellow ballThe annswer is negative: no long-ranged correlations and no long-ranged interactions.

red ball Agitating active matter from rest:

yellow ball C.M. Rohwer, M. Kardar and Matthias Krüger, Phys. Rev. Lett. 188, 015702 (2017)

Self-propelled colloidal particles                                                            Shaken Grains                             

red ballFluctuations of the conserved density field satisfy (model B):

yellow ball "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)

red ballTransient fluctuation-induced force between plates:

red ballTransient fluctuation-induced force between two inclusions:

Conserved density leads to transient long-ranged force. (How "universal" is this result?)