What is it that continues to exist after death? If death is survived by a spirit or whatever you want to call it, then what is it made out of? Where can it be found and how does it connect to everthing else we know about ourselves? How do we know?
Now that I have asked the quetions, I will put forward my answers to these questions for you to consider as well.
I will call the existence after death the spirit. And I propose that is made out of energy like everything else, but not a part of the measurable conserved energy, which the physical universe is made of. This energy which the spirit is made of, is given form by the choices we make. These choices are events with both physical and non-physical components.
I will describe the physical component first:
Living is a non-linear process that creates points of bifurcation where a quantum wave collapse is amplified to macroscopic consequences. The result is an event which has no pre-existing cause. Human consciousness identifies these events (which we call our actions and choices) as caused by the self, and our sense of self come from its identification as the cause of these events. Therefore the self and its actions are not in a traditional cause effect relationship, but are an example of self-causality, which means both the cause and the effect come into existence simultaeously. When we make a choice, we also simultaneously choose the reasons which are the cause of our choice.
These self caused events transform the unverse as the usual type of cause and effect travel outward from these events at the speed of light. This is the true arrow of time, for the quantum wave collapse is not reversible. Particles are represented by waves (from which a probability distribution can be computed) which collapse instantly to point (according to that probability distribution), but the point (highly localized wave packet) cannot un-collapse. The localized wave packet cannot instantly revert to the non-localized wave, for the wave packet cannot expand faster than the speed of light. It must expand accoriding to Schrodinger's equation.
The physical consists of energy which is bound in a single definite (macroscopically four dimensional) mathematical form which we call the universe. Everthing physical is an inseperable piece of this whole, bound by the laws which are its shape and form. The energy is bound to this form by the limits described by quantum mechanics. What do I mean? Well for example the energy is bound to a definite quantifiable amount. So we say that energy is conserved. However energy is bound to this quantity only within macroscopic limits defined by quantum mechanics. According to quantum mechanics, during shorter intervals of time (dt) an amount of energy dE need not be conserved according to (dE)(dt)=plank's constant. Here is the real boundary of the physical universe. It is not out there somewhere, but everywhere.
The non-physical consists of energy which not bound to this single unified quantifiable form. The non-physical can interact with the physical only at the boundary, which means that it can only interact within the limits set down by quantum mechanics. The choices of living beings which we described above occur at this boundary and the formless nonphysical causes of our actions are given form by our choices. It is this form which we call the spirit. The spirit is not a piece of the physical universe and so it is not bound by the laws of its form. The spirit is only bound by the laws of it own form, which if you remember, I said was created by the choices of the living creature which indentifies it as the cause of its actions.
How do I know all this? The same way I "know" anything else. It is consistent with my experience of reality. Is any knowledge certain? No. For example, I "know" the sun exists. But everything I have experienced in life could be a dream and when I wake up I may find out that there is no sun after all. The simple point of fact is that regardless of whether my experiences are "real" or not, the existence of the sun is consistent with those experiences. Knowledge is something we take for granted in order to live our lives. It is an hypothesis that we accept on faith, so that our minds can reason, because reason cannot find any beginning. Logic only goes from postulates to conclusions. Reason must start from somewhere and we must take our starting point on faith.
