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 my self 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. Why is that?
Take a look at this picture.

Assume the object in the picture above is a neuron in your brain. Then it can only be affected by other physical objects within the light-cone which is centred upon it at t=t0. All the relevant fields propagate <= lightspeed. Even the brain itself taken as a whole does not exist within a shared present. This is a problem with supercomputers too - the separate logic circuits have to deal with the finite speed of light across the processor fabric.
My knowledge, and sense of present-self, is encoded in the present state of my brain (encoding my personal history) and it gets updated by events within the cluster of lightcones centred on the set of neurons in my brain. Unfortunately, all the lightcones 'point backwards', or more specifically, define a direction. There aren't any which start at my future self and arrive back at my present self.
No dialogue, then.
I'm still there, though, up in 2010. I hope I'm in one piece!**
* 3D slice of a 4D object.
** But even if not, my reality at this point, [July 4th 2006], is unaffected.