How to: Change of research field after thesis [duplicate]

Question

I'll soon have finished my PhD in mathematics in a not top ranked university, and as far as I see it, my thesis is not going to be especially impressive. My goal after the defense is to either leave academia, or make a rather drastic change of fields (let's assume it's the latter). The problem is I have no idea how to operate this change without restarting at the PhD level. My advisor has essentially no acquaintances in the fields I'm interested in, and I tried sending a few emails to people working on those fields, but the reception was mostly cold. A common advice (given around me and seen here) is to continue with a postdoc and try to change fields by transitioning step by step from my current fields to the ones I'm aiming for. I see two problems with this advice:

• If your track record is not exceptional to start with, simply getting a postdoc might be hard.
• Such a neighbor-to-neighbor approach to transitioning might prove to take a lot of time, spent working on problems I'm not really interested in, for the non-guaranteed goal of eventually working in my desired field.

In summary, I'd like to ask for any advice on how to operate such a change.

Edit. More details:

• My desired field is within maths; I'm interested by a relatively wide area rather than a specific problem.
• My current work is not in some super specialized field: I have worked on different questions that don't require much background so far.
• I have read this answer already, which is quite pessimistic but feels spot-on to me. Nevertheless, I'd like to get some actionable advice, if possible.
• One thing maybe deserving of clarification: I'm not especially interested in staying in academia long-term, so the "publish or perish" point of view only applies to me as far as getting to the very next step. My goal with this change of field is essentially about having the opportunity to learn maths that I'm very curious about and would like to understand, rather than career-building, I think.
• I have thought about starting with a new PhD (even applied to a program) but:
  • People don't seem to be very receptive to such an idea (“Why would you do a second PhD?”)
  • I'm not sure I have the energy to start such a process over again (it was quite taxing psychologically the first time, so a second might prove hard).

Answer 1

While there are reasons to be pessimistic because of the general job market in academia and maybe elsewhere at the moment, I think you are being overly down on both yourself and your chances.

One advantage you have is that you aren't so overspecialized that only one or two positions in the world matches your interest. You have more options. No, you don't need another doctorate in mathematics. You already know what it takes to do research and you'd find another doctoral quest both frustrating and boring.

No, you don't need to change fields right now. Make it a long term goal if you like, and many folks do that as opportunities occur.

What you need to do is get into the game somehow so that you have a financial base from which to do research, whether it is similar to your thesis or not isn't really material. You have skills (mad skilz) that you can apply if you have any guidance at all, such as in a research seminar group.

Use whatever resources you have (advisor, other faculty, ...) to find a position with research responsibility. Forget the rest at the moment and focus on just that. It isn't easy at the moment, but if you can get that one job done then the rest can follow.

Moving to industry might make things harder, as you most likely then have job requirements that you must meet and have less opportunity to set your own goals. There are some fine positions available in large companies, but not all of them come with much freedom to explore as is more typical in academia. But already having some skill in a broad area is probably and advantage in looking for industry work. You can be flexible.

First build a base, then worry about the field.

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Historical note: Many of us old folks, recently retired, also finished degrees in terrible job market times. After the US landed people on the moon, funding for math and science evaporated overnight when, up to that time, there had been a tremendous hiring push. There were literally no jobs. Many of us held on and got something from which to build a career. Maybe it wasn't the career we envisioned when we were students, but it was interesting, provided that we made it interesting. We had a life that we enjoyed, did some good work, and survived. It turned out to be not a downer, but a satisfying life.

Answer 2

I was in a similar situation at the end of my Ph.D.. What worked for me was:

• watch for postdoc vacancies to be advertised in my fields of interest;
• each time an interesting vacancy appeared, send an informal pre-application enquiry to the PI;
• shortly before the application deadline, submit an application, even if the PI hadn't replied to the previous enquiry.