Can nine-dimensional anti-de Sitter spaces emerge from string theory?

Researchers found new solutions in type II string theory that produce nine-dimensional anti-de Sitter spaces (AdS₉)—higher-dimensional geometries central to the holographic principle. Type IIB solutions with varying dilaton fields remain finite even at singular points, yielding well-defined thermodynamic quantities. Type IIA solutions, by contrast, suffer divergences. These constructions may illuminate how gravity emerges from quantum field theories in unexpected dimensions.