What happens when you die?
Life is a transient state of being, followed, by another condition called Death. Your existence didn't begin with your birth, nor will it cease upon your demise. Existence is eternal, states of being are temporary.
Actually, the concept of "Life After Death" is a no-brainer. You were certainly dead nine months before you were born; you are (presumably) alive now, so the matter really isn't debatable. But a number of rather profound and interesting questions do arise from the premise, and having been dead as currently as 1948, I feel my recent experience as a decedent makes my conjecture just as valid as that of any who care to abuse the subject.
Why haven't we detected ourselves within our corporal garb? What is life?
Just consider the state of being from which we begin our trek into life. Due to our diminutive size - that of an elemental particle - our presence can't be detected by our primitive technology. Systematically we envelop ourselves in terrestrial materials genetically encoded by our host (mother) to assure we benefit from the latest version of modern corporal engineering. As we process the elements fed to us, we craft our shell and become proficient in its use. We learn to "Wear the Mud" - so to speak.
From galaxies to planetary systems and atomic architecture, nuclei are a common natural feature. A defined center of being would be necessary to any real sense of identity. Your nucleus probably resides between your ears and behind your eyes, spreading its domain throughout the nervous system to monitor every portion of your body except for the hair, nails and other anatomy where the nerves do not reside. What we experience as thought and consciousness seem to be spawned - or at least amplified and enhanced - by the brain and nervous system of our body. As external stimulus filters through our corporal shell, our actions and reactions cause changes in the chemistry and physiology of our body which are readily discernible - muscular movement, electrical and chemical reactions. We act and react to the condition of our own elemental being (first level experience), the condition of our corporal shell (second level experience) and the condition of its immediate environment (third level experience).
Death: Nature's Time Machine
It doesn't take a chemist to know that the more concentrated something is, the higher its potency. The less surface area an element exposes to its environment, the more control it exerts over that area. As a life particle expands its corporal domain throughout a system of nerve fibers, the amount of surface area exposed to external forces must be tremendous, and the amount of effort it must expend to maintain control must be vast. The metabolism or internal effort that a life form must maintain to cope with the processes it compels must be phenomenally high in contrast to its condition in the death state. When you are awake, your metabolism is at its highest and time seems to pass at a normal rate. When you sleep, your metabolism slows and hours seem to pass in what seems to be only minutes. Upon your demise, your internal metabolism may slow to a mere crawl. Years, centuries or even eons may pass in the blink of an eye. Of course, I have no hard data on the death cycle. My memory just isn't that good and the deceased are not prone to engage in interviews and studies. We may pop back into life after a brief respite, or some of us may skip through a couple of eons of cosmic change, re-animating as some ugly primitive critter just as life gains a toe hold on some new planet orbiting some future star. Don't worry too much about how long it takes, you literally have all the time in the world.
"So," you ask, "if I existed before I was born, if I lived a life prior to this one, why can't I remember it?"
Good question . . . thought you'd never ask.
Have you ever tried to play a 78 rpm record on a DVD player? Indeed, the human format has only been around for a very short time on the cosmic calendar. Any prior life experience you may have had on this planet may not have been of the human variety.
What you experience as memory is your detection of a change in condition that a stimulus has recorded upon BOTH your body and your being. Conscious thought is played back upon the senses - this feedback is often called the "mind's eye". You no longer have the same brain or nervous system to call upon to replay the events of a past life. The impressions of previous events are not ingrained upon your present body and the corpse you currently inhabit may be somewhat different in its architecture. Memory seems to be a call on demand feature inherent to our nature. When you are awake, you tend to recall those memories which best serve the processes of your waking consciousness. You are more likely to remember your dreams while you are still in a semi-dream state and unless you make a conscious effort to record or bookmark them, you often can't recall them after you are fully awake - even when you know you definitely experienced a dream. Even waking memories tend to decay over time unless they are reinforced periodically. This doesn't mean you may not still have memories from past lives, but they may not be retrievable by your consciousness. They would be dim, you would have to have some reason to summon their recall and the effort required to retrieve and decode them may not be worth the trouble.
When you eventually die, whatever level of consciousness you experience may well be familiar. You may even vaguely remember past death states - probably more as an instinct than as the vivid sounds and images generated by your living "mind's eye".
So what happens when you die?
Only the currently dead know for sure, but the clues seem to indicate two possibilities -
1) If life IS a cycle, the life form probably returns to its concentrated pre-life state and its metabolism slows to a crawl. As in life, there may be a gradual maturing process - at the end of which it eventually finds its way into the womb of a suitable host (same species?) and the cycle begins again - creating a new rung in the ladder of evolution.
2) If life is NOT a cycle, the life form may - or may not - maintain its configuration (a bald, naked ghost with no finger nails). If the entity has the property of mass, it may be bound to the planet - else it may move (or be moved by random forces) to parts unknown to begin a new realm of experiences.
I'd put my money on #1. It is the inherent nature of all forms of existence to maximize control over their environment. As I see it, the most powerful forces in the environment are material, so control over matter is highly prized. Being ethereal in nature may be fun for a while - soaring over the earth, slipping under the door and going to concerts for free, etc., but it is next to impossible to log onto the internet without fingers to punch the keyboard. I think I'd REALLY miss steak and potatoes . . . and beer. I'd miss the company of kindred spirits - humanity - with all of its foibles and imperfections. But most of all, I'll miss the love of my life - my lady Linda (Poopsie), my soul mate to whom this site is dedicated.
So, with the understanding that your fundamental essence has always existed and will forever continue to do so, do you still yearn for immortality? That would certainly be foolish. Would you prefer to have a Homo Habilis appearance with a commensurate IQ? Would you enjoy crawling around as a silicon based corporal bug in that same worm frame you inhabited back when a massive white-hot star that went extinct trillions of eons ago hosted your native methane planet? Death is as natural as life, in fact species could not evolve without it. It's a valuable asset not to be feared or eliminated. Even pain has its place. It precipitates change. It's nature's way of saying you screwed up and screwing up should, of course, be avoided at all costs.