fear of death

Is it possible to fear what you don't know?

I guess it is in the sense, perhaps, that I might fear an atomic bomb based on historical evidence. I don't have an intimate, experienced knowledge of such a bomb, but intellectually, I can extrapolate. A-bombs are a bad business.

But does the fear of death fall into the same category? No one that I know of ever returned from the dead to report that it was a bad business and, since in the history of mankind there have been plenty of people who gave death a whirl without reporting negative effects, on what basis can death be rightfully or sensibly feared?

I may say, "I fear what I don't know," or "I fear the apparent absence of what I do know," but it sounds pretty iffy to me.

I am not alleging here that I don't fear death. I am just sniffing the fire hydrant of the issue.

My own hunch is that the fear of death is not a fear of the unknown, but rather a fear of the known. But if this is the case, what is it, precisely, that is known and thereby feared?

I haven't got the answers to any of these questions and I seldom dwell on them, but I chew gum every once in a while and this is just one stick.