This note is a part of my Zettelkasten. What is below might not be complete or accurate. It
is also likely to change often.
What is death? The most general answer (which is found in dictionaries) is "the end of life". Death doesnt exist in absence of life. Thinking of death too, cannot happen without a consideration about life. More pointedly, thinking of what is means to be alive.
There are many types of deaths, each of them coming the end of a different understanding of life (Keep in mind that I am a non-dualist)
One way of thinking of life is to say that life is presence of awareness. This way of thinking might not be all that generalizable, but lets keep our lens anthropocentric for now. If life is awareness, I live and die thousands of times every hour. My awareness of my own existance comes and goes - one moment, I am present, another, I am lost in the flow of thought, the awareness forgotten. During the writing of this sentence itself, I have lost awareness a dozens of times. It happens. When I consider this death, it doesnt seem all to big a deal. One day I'll lose awareness like I have likely done a billion times so far and I wont come back. So thats that.
What is this entity called I? This I is constantly in a state of change, every single moment - is the I of a day ago dead? This is like the mythical Ship of thesues.
Another way of thinking of life is the functioning of the body-mind that I call myself. This death is the most popularly accepted one. One day this body will stop working and there will be nothing more of me.
An alternate way of thinking of life is that it is, quite simply, existence. The death, in this case, would be the erasure of the record of existence.
One record of existance is memory of me within other people. Each person who knows or remembers me keeps a version of me alive within them. (Does this version have to be close to me?). When a person who knows me dies, I die a small death - a version of me that existed uniquely in that person dies. True, final death will come when the last person who remembers me dies.
Another record of my existence is this universe itself. The universe itself contains information of my existence. I will die when eventually, all the energy and information in this universe will disperse in a heat death: https://en.wikipedia.org/wiki/Heat_death_of_the_universe
This death is the one of most interest to me. My death is the death of the universe (therefore I am the universe?). This begs the question - what is the universe?
Is the universe a wave of energy, which will begin and end? Or is it something else?