Interestingly it seems that all physical theories are time-symmetric, with the notable exception of thermodynamics which states that energy will always dissipate. To quote the P.J.Carroll book I mentioned earlier -
"There is good reason for this: there are many more future states in imaginary time which correspond to dissipative futures than to non-dissipative futures. For example, there are many ways for an egg to break but only a few in which it can stay in one piece. This is what makes unbreaking eggs so difficult. There seems to be a similar but longer-term mechanism at work that favours the development of information-rich systems, such as living beings, simply because such systems have a larger range of possible future states than less interesting systems. Thus, an imaginary time dimension will explain the otherwise inexplicable predilection this universe has for increments in both entropy and information content, which we experience as a one-way flow of time and evolution."
'Imaginary time' is Carroll's / Chaos Magick Theory's term for an extra time dimension that contains all possible pasts and futures, and can be identified with the parallel universes that appear as a consequence of the Quantum Physics wave equations. These equations use 'imaginary numbers', hence the naming of 'imaginary time'. CMT uses the term 'pseudo time' to refer to ordinary time "created by memory and expectation which has no real existence apart from the moment of the present".