I have a master's degree in Computer Science. I have applied to PhD programs, and decisions are trickling in. I may soon have to choose between two or more PhD programs. I am outside of the US.
Unfortunately, I have diverse interests. I was advised that a successful PhD application is usually quite specific, so I made each of my applications very specific. I wrote to a professor working in decision making (AI), another working in computational learning theory, another working in computer music, another working in quantum & parallel computing, another working in logical foundations & philosophy of computation. With much enthusiasm, I informed each professor that I was interested in pursuing a PhD in his / her field. This is true. I am interested in each of these fields, and know something about each of them. When advised to apply, I did.
The problem is - being interested in each of these fields also means that I'm interested in all of them. (There are more areas of CS I'm interested in. What's worse - my interests are not even restricted to CS. For the purposes of this post, I'm restricting myself to only the mentioned areas.) So when I choose between PhD programs, I'm choosing between completely different areas - and that is surely going to be excruciating.
This is not a case of not knowing my 'true interest' now, only to discover it later. I have no 'true interest'. I have always pursued numerous unrelated things in parallel. I love all my interests equally. In fact, I love the feeling of 'being interested' more than the interests themselves. Whenever I've tried to restrict myself to one topic of study - even for a month - that feeling is lost, and I am quickly bored. As a result, my skill-set is a classic case of a jack of all trades - master of none. The worst part is - everybody knows that a PhD is about getting deep into one specific topic. It's not about breadth - it's about depth. Even if I were to choose one of the PhD programs (and I must choose one), I have a feeling that I might get bored quickly and be prone to constant topic-changing / transferring. Again, this is not about being fickle - it's about following my heart, and my heart takes me to different things at different times.
Do you think I'm likely to fail / never complete my PhD? What are the best practices for dealing with diverse interests?
Update (2018): The good news is that I received my Ph.D. last year. The bad news is that many of the concerns I described in this question did rear their ugly heads in grad school (for example I became one of those PhD students who reads and reads and reads many things but doesn't get actual research done). Though I managed to graduate, the quality of work leaves much to be desired, and I am currently facing a difficult job search, and beginning to suspect that I have no future in research.