title: Experimental demonstration of metamaterial "multiverse" in a ferrofluid.
abstract: Extraordinary light rays propagating inside a hyperbolic metamaterial look similar to particle world lines in a 2 + 1 dimensional Minkowski spacetime. Magnetic nanoparticles in a ferrofluid are known to form nanocolumns aligned along the magnetic field, so that a hyperbolic metamaterial may be formed at large enough nanoparticle concentration nH. Here we investigate optical properties of such a metamaterial just below nH. While on average such a metamaterial is elliptical, thermal fluctuations of nanoparticle concentration lead to transient formation of hyperbolic regions (3D Minkowski spacetimes) inside this metamaterial. Thus, thermal fluctuations in a ferrofluid look similar to creation and disappearance of individual Minkowski spacetimes (universes) in the cosmological multiverse. This theoretical picture is supported by experimental measurements of polarization-dependent optical transmission of a cobalt based ferrofluid at 1500 nm.
authors.affiliation: Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, USA. smoly@umd.edu
authors.forename: Igor I
authors.initials: II
authors.lastname: Smolyaninov
authors.forename: Bradley
authors.initials: B
authors.lastname: Yost
authors.forename: Evan
authors.initials: E
authors.lastname: Bates
authors.forename: Vera N
authors.initials: VN
authors.lastname: Smolyaninova
mesh_terms: D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008422:Materials Testing; D012031:Refractometry / Q000379:methods*; D013696:Temperature
chemical_list: D058185:Magnetite Nanoparticles