I have a question, hope maybe someone has seen some papers on the subject and can point me in a direction. I searched arxiv/astro-ph with the search paprameter "arrow of time" but could not find anything in the following specific area: Hypotheses: a) Time is symmetric. b) When the big bang occurred, half the mass went forward in time, half went backwards in time. Anti-matter universe <------- Big Bang --------> Our universe Would provide a simple explanation of why we see effects dominating in one time direction and not the other... it is a result of initial conditions. I am pretty certain someone must have speculated on this before, there are probably plenty of citations but I can't find the right phrase. Any suggestions? There have been new interpretations of QM which involve time symmetry (I searched on that too) which I suspect would have some cosmological implications. So that is what is driving the question.