The alien seems to be a pretty much normal human. The alien starts with a nasty lecture, "Do you realize that you could have changed the entire history of your planet with your ill considered time travel?"
I jump in, "Your statement makes no sense. I went back in time some 16 Earth years. Conceptually, I could have changed history for only the last 16 years. As far as ill considered time travel, how did I time travel?"
The alien pauses for a moment and then says, "Our science is much more advanced than the science of your Earth. Our science has learned the theory of time travel. However the risks of sending people into the past was just too great too even try the experiment. Then one of our scientists managed to build a time machine." Again the alien pauses.
"Let me guess, the scientist who built the time machine was financed by a group who lost a war, at sometime in the past, and wanted to change history by sending an agent back to let their side win the war."
