It occurred to me yesterday that I obviously will never acquire the ability to time travel (at least into the past) since I have no evidence of it. After all, if I ever do acquire the ability, then it does not matter at what point I do so (age 30, 60, 100, etc.) since whenever it does happen, I can always go back to any point in the past. The reasoning is that if I do acquire the ability to go back (presumably to help myself make my—uh, our—life better, fix a mistake, etc.), then I would have done so and would know it. It does not matter if it happens tomorrow or 50 years from now; either way if I go back to my past then it has the same effect. Yet, I have never been visited by myself and so I clearly do not ever acquire the ability in my lifetime.
However, that reasoning falls apart because there is no guarantee that if I did acquire the ability, that I would come back to this point or any previous point in my life. It is entirely possible that for example, in 10 years I get the ability and then I come back in time tomorrow morning. Just because I have up until now, never been visited by my future self, does not mean that I do not ever acquire the ability, since I did not need to come back this far. Tomorrow morning however is a different story, something may happen tomorrow morning which requires my intervention and so I will be visited by myself and thus know for sure that I do eventually come across the time-travel technology.
The point is that while there is no current evidence to support the idea that I will ever be able to travel back in time, it does not rule out the possibility since I may just not need to come back this far. This is truly the definition of “you never know what the future holds”, since for all I know, tomorrow I may be visited by myself from the future. It’s impossible to completely rule that out without entirely disproving the possibility of time travel altogether.