The Uncertainty of Evolution by Natural Selection

We're already on this technological trajectory, where it's not too hard to imagine that we could achieve this capability. It is also improbable that extraterrestrial aliens elsewhere in the universe would evolve to be bipedal and generally look next so much like us. Most UFOs seen in association with these beings have a form consistent with what we would expect to see in a craft capable of manipulating space-time. These are the very devices that allow our future progeny to venture backward across the landscape of time.