When and how to choose your field

[dsanz]

I will start grad school physics this fall. My question has to do with choosing my field of research now that I'm in. In one part of the "So you want to be a Physicist?" article it basically says that you should first worry about passing your quals, before worrying about your research project. However, I am under the impression that one element of the quals is presenting a research proposal to the grading committee. Also, I think some universities give you a period of say, 1 year, to come up with your field.
Anyway, I am mostly hoping that some grad students or phd's can comment on this...
First, how did you choose your field? This is becoming quite hard for me, since I have investigated a bit into many fields, and I like many of them. So having to choose one for the rest of my career (at least that's the plan) is quite stressful. How did you decide on your passion (or maybe you were partly influenced by other things?).
Secondly, when did you do it? Did you know your field right away? After one year? Two, three? I know there won't be definite answers on this one, but at least some input to give me an idea of how things work would be nice.
Thank you very much. Cheers.

 

[Choppy]

You have to keep in mind that such statements are school-specific. In some places you're expected to choode a field right away. In others you wait until after your qualifying exam.

I chose my field through serendipitous trial and error.

After undergrad I enrolled in a master's program and chose to go into plasma physics. I did not know much about the field at the time, but it caught my interest. I did okay, but found I didn't have much of a passion for it. One of the most important things I learned was that in order to do well at the graduate level and above, you can't just do what's expected of you. You have to have the desire to explore a little on your own and I just didn't have that drive in plasma physics. I finished the degree, but decided not to pursue a PhD in that field.

What did develop was an interest in medical physics. Towards the end of my master's degree I found I was going out of my way to attend the medical physics talks at hospital near our university. I applied to a couple of medical physics PhD programs and got in. In both cases there were already a couple of somewhat pre-defined projects waiting to be taken up so I had the advantage of picking one, along with a supervisor, right away. Although, we did not have to decide on a project until the end of our first year.

In my program, the candidacy exam came after ~ 2 years (set by the supervisory committee) and involved examination on aspects of the student's project - as well as both our field and physics in general.

 

[eri]

If you're starting grad school in the fall, you'll have a limited number of fields to choose from based on what's offered at that school (unless you plan to transfer). I'd recommend trying to figure out what kind of job you want to have in 10-15 years, and then look into the fields that might get you there. Talk to professors about where their recent graduates ended up working - postdoc, faculty, industry, government, etc. Career paths for, say, astrophysics, can be a bit different from those in condensed matter physics just based on the applications of your research skills.

Your choice of adviser should also depend at least a bit on the person - you don't want to get stuck working with someone who's always unavailable, who's working in a different specialty than what you want (they won't go to the same conferences as you, which means they won't be there to introduce you to the right people who might have a job opening down the line), you don't want to work with someone you don't get along with. And it's OK if that's part of the reason you pick your field; you don't get stuck there. While it can be hard to go from something like astrophysics to medical physics, jumping around topics in astrophysics isn't as hard.

 

[dsanz]

Thanks for your help.
My school is quite big and there's a lot from where to choose from. I think they give me a year to choose my field. The biggest factor in my decision should of course be what my passion is, but one cannot help but think also about their future. That is, how the market is for every field. I like theoretical physics, but I think that's even a bit more competed than the other fields. The other field I like is condensed matter, which is quite different, since you can learn useful stuff for the industry, you're not just directed towards the academia.
However, if I were to tell you that I really want to go to academia (yes, and go through the long postdoc, etc process), how do you guys see the future for theoretical physicist? I don't need the whole "it's a one in a thousand shot for you to become a professor". I'm talking about how much different or difficult is it to land an acadmic position if your field is theoretical physics as opposed to other fields (which I think get grants a bit easier, but I'm not sure).

 

[eri]

Theoretical physics might sound cool, but it has fewer applications than experimental or computational physics, which means fewer job options when you graduate. Also, you can do theory in any field (theoretical astrophysics, theoretical particle physics, etc) so that's not a field of study, it's how you approach it. Theoretical condensed matter is definitely an option. But the jobs tend to be either at colleges or national labs, neither of which are easy to get. And you're more likely to see job ads for an experimental physicist at colleges than a theorist - at the undergrad level, which most schools are, they need people who can run labs, teach experimental classes, and involve students in their research, and it's easier for students to jump into lab work than theory. No, it's not necessarily easier to get theory grants than experimental or computational. Especially since it can be harder to justify your research and what useful results it will have.

 

[dsanz]

Theoretical physics might sound cool, but it has fewer applications than experimental or computational physics, which means fewer job options when you graduate. Also, you can do theory in any field (theoretical astrophysics, theoretical particle physics, etc) so that's not a field of study, it's how you approach it. Theoretical condensed matter is definitely an option. But the jobs tend to be either at colleges or national labs, neither of which are easy to get. And you're more likely to see job ads for an experimental physicist at colleges than a theorist - at the undergrad level, which most schools are, they need people who can run labs, teach experimental classes, and involve students in their research, and it's easier for students to jump into lab work than theory. No, it's not necessarily easier to get theory grants than experimental or computational. Especially since it can be harder to justify your research and what useful results it will have.

I was referring to theoretical high energy physics. Anyway, sure looks scary going into theory... Now I'm really unsure about where I'm heading. I sure feel like I'm more inclined towards theory, actually I stated theoretical CM as my prospective field in my application. I'm willing to put my life and heart into it, but the job hunt scares me (and what's worse, I'm not a US citizen).