Trying To Figure Out Death

What is this world about, does anyone really know, all we seem to have are guesses, theories, dreams and opinions. Why can't we have more grounded answers to help us find our way through it, separating everything into spheres of our brains. Trying to figure out the one single factor that will cure death in our lifetimes so we never have to feel the loss of loved ones or our lives devastated by it. What is the common denominator of every death that has ever happened, once that is known there will never be death again on this earth.