...probably doesn't exist, actually.
Einstein famously said, "Put your hand on a hot stove for two seconds and it seems like two hours. Sit with a beautiful girl for two hours and it seems like two minutes. That's relativity." This is not a joke, because humans do not perceive time. Our sense of time is a perception of changes in our surroundings as well as our experiences with time. When we were children, days seemed insufferably long, and years seem like lifetimes. This is because we didn't have many of those under our belts, indeed, for a baby that had only lived a day, the next day is as long as its experience.
"Small wit could not compare to larger intelligence, those who were short-lived cannot compare to those who lived long.
For those worms that would die the day they were born, they would never know how long a month is.
For those frost cicadas that never lived for longer than a season, they would never know how long a year is.
This was, however, only a 'small year.'
There was a great turtle to the south of Chu, whose spring lasts five hundred years, and its autumn another five hundred years.
In the ancient times, there was a great Elm tree, whose spring lasts a full eight millennia, and its autumn another eight millennia.
This is the 'greater year'.
Even today, Peng Zu, famous for his eight hundred years of longevity, got everyone wishing to live as long as he does, isn't the short-sightedness sad?"
- Zhuangzi: Journey of Utmost Freedom
Indeed, 16,000 years is unthinkably long for us, and even 800 is so. However, no matter how long the years are, for us. We will never be able to experience anything longer or shorter than a lifetime. As we accumulate years, the past becomes compacted down, and time seems to flow faster.
Indeed, this makes any kind of reincarnation-based afterlife extremely unattractive. Suppose there are N souls in existence. N could be constant, increasing or decreasing. All of which are extremely bad for the prospective deathseeker. If N is constant, then there is a necessary bijection between souls and bodies. Thus, if you're reading this piece, you're already amongst the top .00001% of the souls on this Earth in terms of well-being. Your next life is therefore almost guaranteed to be infinitely worse, and the worst part? You won't even get the mercy of a shorter lifetime. If N is increasing, then as a consequence, there are even -more- souls competing for those preciously small set of "people well off". Worse is that new souls may be created by splitting old souls. This is as catastrophic as N decreasing, which also carries a risk that you just might be destroyed.
"But Oblivion is preferable to this life" you say? Well. The problem with that is it's a contradiction for your being, which has been obliterated, to observe oblivion. Therefore, the relativity of perception kicks in again, and just like you can only approach but never reach a singularity, you will instead spend a perceived eternity dying, and if you chose some inelegant way to die, then you will be suffering its pain for the rest of eternity, never able to stop it as your perception slows to a crawl, and you lose control over your limbs.
Of course, this is assuming the Copenhagen Interpretation of Quantum Mechanics, in which your observation of yourself causes your state to be known. In the multiple-worlds interpretation, subjective death is impossible. However, notice that only subjective death is impossible, as you cannot observe worlds which you're dead in. There is nothing that will stop you from being stuck in a timeline which you're completely crippled for the rest of eternity, nor is any of the cases where you survive guaranteed to be painless.
Of course, there's also the chance that one of the world's religions is actually correct, and, quite frankly. I have yet to read about any religion condoning suicide, and most enforce their morality (and thus the survival of their religion) by threatening with an eternity of pain and torment if you violate their tenets, so, basically the same as above.
Thus, perhaps this will put a bit of fear about death back into people, as it is one of the basic instincts required for all life. Odds are more than likely that the "release" death supposedly brings does not exist, or is highly unlikely.
Next time on Ban Immunity: the End of the World and you.