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I am a first year graduate student in a completely theoretical field. How does one go about collaborating online or otherwise with researchers from other institutes/universities? In particular, if I am interested in a problem or an area which is not very well represented at my current institution, how do I approach researchers from other institutes to start a collaboration assuming I have the basic background to start research? Should I have a very particular problem/idea in mind while contacting a potential collaborator, or is it unusual if I approach a researcher just because I am interested in his work and would like to learn more and work on it with no particular problem in mind?