Making sense of the bizarre behaviour of horizons in the McVittie spacetime

摘要

The bizarre behaviour of the apparent (black hole and cosmological) horizonsof the McVittie spacetime is discussed using, as an analogy, theSchwarzschild-de Sitter-Kottler spacetime (which is a special case of McVittieanyway). For a dust-dominated "background" universe, a black hole cannot existat early times because its (apparent) horizon would be larger than thecosmological(apparent) horizon. A phantom-dominated "background" universecauses this situation, and the horizon behaviour, to be time-reversed.