Albert Einstein wrote the following, in a letter of condolence to the sister and son of his long-time closest friend, Michele Besso, upon his death, four weeks before Einstein's own (18th April, 1955).
"Now he has departed from this strange world a little ahead of me. That means nothing. People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion."
Thinking of oneself four-dimensionally is challenging. We think the phrases 'past self' and 'future-self' are metaphors, but actually they are literally true. Somewhere 'up-time' is the future you and me, just as real as myself at this moment of writing, or your moments of instantaneous reality as you read these words.
My past self-slice can communicate with a future self-slice through use of media. If I read this blog later, that's exactly what will happen. I try to imagine that future self, but it's hard. It's not a dialogue: my future self can't answer me back.