According to the first law of thermodynamics, nothing can be created or destroyed, everything is just a new mixture. So if a human being has a metaphysical soul, this matter is assumed to not have any weight in the physical world (unless you are into the whole 21 grams thing) and you could hypothetically travel to new planes of existence (heaven), or reincarnate that way. However, if the soul doesn't exist, and consciousness is just brain matter, then this will be subject to the laws of thermodynamics. This means to me, that if a certain (no matter how low the probability) re-arrangement of the material that made up your brain were to reform, you could share a continued consciousness through a new life. If this is not possible, then this means consciousness is not made of matter, and is therefore a "soul". Therefore, reincarnation is technically (even if unlikely) possible. If this was the case, some problems could still cause annihilation, however, such as if a black hole ate our genetic material (along with our galaxy). Heat Death, if possible, could destroy our chance of reincarnation by destruction of all life vessels. So do you think reincarnation is a possibility? I think so, however, the personality is destroyed forever, no memories retained, no personal identity carried over, etc. Everything is Tabula Rasa upon reincarnation. I've wrote a few papers on my ideas, so I may update this later... please comment, would love to hear everyone's own ideas and criticisms.