I'm about to complete my PhD in mathematics. I've been working with Group theory (Representations). Besides the PhD I also did a master's in theoretical physics (I took much more courses than necessary to earn the degree and all of them were in advanced level, and did really well). The thing is: I would like to work in Theoretical Physics, and I'd like to use my Math background and apply it to theoretical physics. I love both subjects and I think they are like brothers in a sense. So my question is:

1) Should I apply for a second PhD (In physics)? For me it would be the worst option, since I'd have to spent a lot of time in things that I already know, and I don't see the point of writing another thesis. I heard that in Europe some universities "hire" PhD students as Research Assistants, so maybe this wouldn't be so bad. What you think?

2) Apply for a PostDoc position in theoretical physics? This is the best option in my opnion, but I don't know if physics departments welcomes mathematicians applying for PostDocs positions, Do they?

Observe that this question is not answered in another post, my question is specific to math/theoretical physics research. Besides I'm not thinking in getting a second PhD to "learn" physics, I am asking about what is more reasonable when considering to do research both in math and in physics.

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    Doing a second PhD is close to useless compared to spending your time in any other way. Receiving a PhD is a testament to your ability to do independent research. Obtaining one shows you can do that, obtaining a second one doesn't really add anything. Commented Jun 16, 2014 at 15:02
  • My initial comment was deleted, but concerning your edit, Pat's answer in the linked question answers your question, even in math/theoretical physics: "A major part of doing a PhD is learning how to do research and handle working on problems which sit on the edge of what is known. You've done that already. Doing it a second time is unnecessary, expensive and time consuming.". Don't do a second PhD.
    – user102
    Commented Jun 17, 2014 at 11:51
  • @MarcClaesen: My PhD in mathematics doesn't testify to my ability to do independent research in experimental biology, or in history, because the idea of what constitutes research, or at a more fundamental level, what constitutes truth or knowledge, is vastly different in the different fields. (But IMHO math and theoretical physics are close enough.) Commented Jul 8, 2018 at 3:37

1 Answer 1


Anyone will hire you provided you can convince them you are better than the other candidates. You already have a PhD in Maths, you have to show them you have the skills and knowledge to complement their baggage and help solve their problems.

In the Mathematical Physics department in my undergrad university (Spain), there is at least one postdoc that is mathematician with a PhD in Economy, and two physicist readerers that works in Applied Mathematics.

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