What to do when your student is convinced that he will be the next Einstein? As an adviser, I have found it to be a detrimental motive for a student to focus solely on surpassing Einstein in achievement, for many reasons. One student in particular has busied himself with the deconstruction of relativity and strives to break it down and replace it with a much better system. Not only that, he's attempting to construct a theory of quantum gravity and the refutation of string theory, among many other ridiculous sounding tasks.

The student told me earlier that "Einstein's physics will soon come to an end." when I asked him about his work on his thesis.  Then when I saw his thesis, it was complete gibberish, wrong in many aspects. I tried to tell him this but he simply wouldn't listen and told me "You do not understand anything."

He then went to looking for a different adviser but failed, since nobody wanted to work with a man who wants to "surpass" Einstein. When he was rejected by everybody, he came back to me and we were on equal terms again. But now, he's trying to write another thesis. And he told me AGAIN that "It'll be something that will break string theory."

Every student that does physics today at least has a feeling, however slight it may be, to be the next Einstein, to have a revolutionary impact on science, but it's quite saddening that only 1 out of 900,000 people would actually do so. And for this student of mine, I know for sure that he'll soon fall into a well and never get out of it again.

This situation can be likened to a very similar situation in mathematics, as if your proof of a famous conjecture turns out to be wrong, say good-bye to your reputation forever.

I must mention that I do not want to drive him away completely from this. If the student indeed finds a "real" problem in fundamental physics, then let him work further on it. But this must not be the only thing that he should work on, which he is doing with the most robust motivation.

A big problem is that the student has a highly peculiar personality and is introverted; if you tell him something, he has a distaste for authority and considers himself to be the "smartest" and superior than all of everybody he knows, including me. He says that "People in physics today lack imagination" and things of this sort.

I am rather confused. What should I do? Should I try to leave him, or should I tell him in some way to quit doing this and focus on something more plausible and if he doesn't do this then I should do something else?
Let the standard processes of education and research take their course. This student will probably not survive them to receive the degree, and that is as it should be. Tough love: warn, then let the system do its thing.

The central issue I see is that this student is clinging tenaciously to a goal of disruptive fame rather than a goal of advancing research. This happens; it's a difficult thing to screen out at the application stage (where unreasonable ambition is not entirely uncommon, and not usually a dealbreaker). You can suggest that this is an inappropriate goal, and it sounds as though you have -- but you can't force the student to hear, much less change.

I would be inclined to keep my interactions with this student as concrete and immediate-goal-oriented as possible. Have an agenda for every meeting, and pull the student back to it when a megalomanic rant is imminent. Deflect, e.g. "Yes, but when will you have {thing with imminent due date} done?" or "Interesting. Write that up into a conference abstract and submit it to {conference}."

You are well within your rights to "fire" the student as your advisee, I would think. I don't know how that works where you are (or whether it's even possible), but to some extent your students become part of your professional reputation, and this one will not reflect well on you.