Life after death? Mediums, and Aliens.
...Fuck, don't make me write an essay on that. Already tried that once, it was disastrously complicated. All I can say is that it involves determining how an observer perceives reality as brain tissue decays to dust. I don't believe in life after death though, but rather an observer experiences a level of coherency the more complex an observing system is, and life is the higher potential of this coherency. So in "death", you only reside in a dormant state and can potentially elevate again. The reasoning for that is that we all emerge from this dormant state before, after all we were born to exist right now, no reason why it wouldn't "repeat" itself. Unless entropy affects that, then yeah... Shit it happened again.
Mediums, well that's all psychological, nothing paranormal about it. I could go on about how the mind is brilliant are imagining things and deducting information we absorb subconsciously so well, but again TL;DR territory.
As for aliens, there's likely a lot of organic life out there as in basic cells or even just components of life. Problem is though, you need very ideal circumstances for a ecosystem to evolve uninterrupted by cataclysms enough to form more complex life. Despite that, there's likely billions of rocky planets in this galaxy alone, so it's possible there's quite a few civilizations out there, but way beyond our reach, maybe even theirs to us. If there's FTL to factor in, we're already long fucked, should they want Earth for whatever reason.