Imagine the following experiment: Scientists have made a machine that can create a traversable wormhole and can also accelerate one end at near the speed of light and bring it back. A time machine. Suppose the dilation between the two ends is 10 years. As soon as the experiment brings the traveling end back, my future self walks through. He decides to stay with me until 10 years have passed the usual way: a long ten year wait. Present self, now 10 years later, is about to walk through the worm hole to go back 10 years. I bid goodbye to future self, who remained with me this whole time (because I am such a swell future guy), and step through. Who is waiting on the other side, 10 years in the past? Is it: 1.) Just present self when the machine was first turned on? 2.) Present self and future self #1 3.) A black hole that destroys the machine because of the possible infinite numbers of me showing up simultaneously, thus self consistency or worse, paradox. This poses another issue: does traveling into the past create matter? Consider the following: I go back 100 years into the past via some fantastic means (and avoiding parallel universes for the moment). 100 years ago, the specific particles/atoms/molecules that are going to make me up maybe in the soil, part of an animal, floating in the atmosphere at that time. So, I now have two sets of me: present me as a person and what will come to be me 100 years later stuck in a tree/soil/etc. Does this form of time travel violate the conservation of matter/energy?