Similar constructions work for the Reissner–Nordström geometry [398Jump To The Next Citation Point], as long as one does not get too close to the singularity. (With c = 1 one needs r > Q2∕(2m ) to avoid an imaginary fluid velocity.) Likewise, certain aspects of the Kerr geometry can be emulated in this way [641Jump To The Next Citation Point]. (One needs r > 0 in the Doran coordinates [176, 633Jump To The Next Citation Point] to avoid closed timelike curves.) As a final remark, let us note that de Sitter space corresponds to v ∝ r and ρ ∝ 1∕r3. For further details see Section 2.5.