The Observable Evidence:
When you die the energy that forms your mind and nervous system departs your body on a frenquency of energy outside of our visible spectrum.
When the 'bio-electricty' does its disappearing trick, the human body loses aprox. 1 Oz in weight... something with recordable mass leaves.
There is an endless number of reporting sightings of ghosts, from ancient times until now.
There is a huge number of those who believe in moving on to a better place after death.
There is a huge number of those who believe in re-incarnation... apparently even Christians.
If we combine all of them, I'd have to say what happens is that your 'bio-electricity', formerly you, ceases/slows in motion and thus drops in energy state... this, for all intents and purposes, deletes it from our reality. Afterwards, those with enough will power, mind structure, and overall firmness of their grasp of 'who they are' they can keep themselves together.
Those who appear as ghosts are those who, for what ever psychological reason, just cant get themselves away from somewhere important to them. As their mind has no physical framework to repair itself, and they themselves obviously had issues before death as it is, they are basically stuck this way.
Those who move on, and remember moving on, are those who had, for what ever reason, enough willpower or self awareness to hold their consciousness together... in a journey to elsewhere.
Those who only see a bright light are those who cannot hold themselves together and their energy loses its structure, being merged back with the 'magnetic field' of our planet and there-in being meshed back together with the ambient sphere of human alpha/beta waves surrounding the planet... as the Hindu belief in re-incarnation says, it takes 49 days to re-incarnate... they like every ancient religion worshiped the pineal gland as the house of the soul... oddly in a human fetus it takes 49 days for the pineal gland to form. Your energy, or whats left of it, is therefore transfered to a new host... the mixing and mingling of energy causing a loss of memory and uniqueness, creating a new individual with only residual sensations of their past incarnations. (I.E. Memories and so-forth)
Hell would be making your journey to elsewhere, in the form of energy, and getting lost... perhaps on a burning boiling sea of hydrogen like a star, or sucked into and confined and torn away at for an eternity in a black hole.
Those who move on are lucky.
DISCLAIMER: THIS DOCUMENT does not cover all individuals in the infinite and variable universe. This is in no way is speaking on cases of incredible, random, or odds of more than 1 : Pi against probability.