Keepers

The names of those congenital skeptics who insist that time-travel is impossible, even in theory, are Legion. Nor is their stand difficult to comprehend. They say that no man or woman has yet traveled backward to meet a younger him or herself face to face. They say this is immutable paradox. And by way of clincher they add a query as to why, if time-travel is to come, has it never happened? Why haven't we recorded instances of visitations from the future?
However, those in favor of time-travel have answers ready and waiting. These optimists (?) use the parallel universe theory to meet the first question. Such return, they claim, would immediately cause a forking of the Earthways, leaving our version of the world untrodden by time-traveling feet. As to the clincher, they counter-question with a How do we know we haven't had such visitors? Time-travel, when it comes, will come in a far-distant future. At such a distance the mere six thousand years of recorded human history is a mere fly-speck on the annals of Earth. So why should this tiny dot in the continuum have been favored?