I believe there is a possibility for some form of existence after death. One of my favorite theories was that if the universe is cyclic, constantly expanding and contracting, that if I came out of one expansion I could certainly come out of others if this happens infinitely. Indeed if this happened infinitely I would believe that I will live at least my life infinitely, going from my death to nothingness, then after the universe expands time may loop and go back to my birth. This would be true in a deterministic world with a cyclic universe. In a non-deterministic world with a cyclic universe I still believe that I would go instantly from my death to my birth and relive my life, however sometimes I may live different lives and possibly even exist in forms that are different from what I currently recognize as myself, but still have a sense of being and perception but with a new ego and neural network and such. Unfortunately it seems that the majority of physicists think that we live in a universe that will expand out into heat death and that the universe and time will one day die. However I do not think anyone has proven this and I do not think anyone knows for certain, so it is unlikely but it could happen. Another possibility for life after death in the realm of possibility is that we live somewhere in a multi layered computer simulation. I believe that this theory is taken seriously by a number of respectable researchers , and even though it may be a long shot it is still in the realm of possibility imo. If I can be programmed to exist once then I can be programmed to exist again, or the entire simulation could be run over from the start after it finishes. So long as the highest layer running the first simulation continues to support intelligent life, all sub layers can continue to exist.