Quantum escape of sudden future singularity

We consider finite-time, future (sudden or Big Rip type) singularities which may occur even when strong energy condition is not violated but equation of state parameter is time-dependent. Recently, example of such singularity has been presented by Barrow, we found another example of it. Taking into account back reaction of conformal quantum fields near singularity, it is shown explicitly that quantum effects may delay (or make milder) the singularity. It is argued that if the evolution to singularity is realistic, due to quantum effects the universe may end up in de Sitter phase before scale factor blows up. This picture is generalized for braneworld where sudden singularity may occur on the brane with qualitatively similar conclusions. (C) 2004 Elsevier B.V. All rights reserved.