I watched a dubbed movie about a man who claims to actually be an alien from very far away. This man meets with a group of scientists who are interested in what he has to say. The man explains that he uses the energy of light to quickly travel anywhere in space. One of the scientists asks whether he means that he travels at the speed of light, to which the man replies that he does not, as that would mean that he would have to travel for thousands or millions of years from where he is from. In one scene, the man and a group of scientists are in an observatory and the man gives them parameters so that they may turn the telescope towards the man's home system. I think, during the observatory scene, the other people tell the man to travel to his homeworld and back, after which the man stands in place and says "Adios", followed by "Hello" and claims that he made the trip, much to everyone's amusement. I don't remember anything else, except for the fact that I didn't finish watching the movie.
K-PAX is a 2001 American-German science fiction-mystery film based on Gene Brewer's 1995 novel of the same name, directed by Iain Softley, starring Kevin Spacey, Jeff Bridges, Mary McCormack, and Alfre Woodard. The film is about a psychiatric patient who claims to be an alien from the planet K-PAX.
At one point he is introduced to a group of astrophysicists who are befuddled when prot displays a level of knowledge about his claimed star system that was unknown to them.
He claims to have journeyed to Earth by means of "light-travel"