# Choosing a PhD field

Tags:
1. Nov 19, 2015

### DeathbyGreen

Hello,

So before I start, I realize that this question has been asked in the past, but all of the threads were over several years old so I'm not sure if the information is still current. I've been thinking about this decision for a while: I'm currently in my second year at a respected institution doing a MS Physics with a concentration in condensed matter (superconductivity). I'm really more interested in particle physics to where I read about it in my spare time. I was considering changing fields for a phd to applied quantum field theory or something similar. I have a background in condensed matter field theory so there is some overlap. My problem is that I worry that after a particle physics phd a scientific job is difficult to find. I've done some research and seen that postdoc opportunities are available, but it's harder for me to find out anything about jobs beyond a postdoc. I do enjoy some parts of condensed matter, so it's not horrible for me to continue in this field, but I feel that I would excel more at something that I was really passionate about. But I wouldn't want to study something I enjoyed for a few years and then end up working at a bank (not that there is anything wrong with that, I just want to stay in the sciences). Does anyone have any advice? Is it as difficult as it sounds to continue in particle physics? Is condensed really the best field to stay in the sciences?

2. Nov 19, 2015

### fzero

The chance that a new PhD will go on to a tenured faculty position in their lifetime is very small. Obviously the chances are affected by the ratio of job seekers to open faculty positions in a subfield and by the quality of the applicant, but on average, the chance is less than 10% in the US for science and engineering. For example, we can look at published studies like http://www.nature.com/nbt/journal/v31/n10/fig_tab/nbt.2706_F1.html comparing the number of new faculty positions vs PhDs awarded by year. Or we can just do math on the back of the envelope, estimating that the average professor might have 10-20 PhD students during their career and that the number of faculty positions doesn't change drastically.

So, even if the faculty market for condensed matter theory was that much better than particle theory (and it is probably not that much better), in a sense we are comparing $\epsilon$ with $2\epsilon$. It is much more important to excel in a given field than to make an average performance in a field with slightly better job prospects. More often than not, the candidates that will be getting the job offers are the ones that stand head and shoulders above the rest.

Hopefully you are the type of person that would excel in either field, but I would suggest that you carefully weigh the statistics against any fresh PhD with the personal value that one or the other option would present to you.

3. Nov 19, 2015

### DeathbyGreen

Thanks for the thoughtful response. I wasn't necessarily referring to tenured faculty positions, although I know that is the easiest to track. With condensed you have many scientific opportunities in government and industry due to the nature of the field's output, but I'm not sure if that exists for quantum field theories or other, more "pure academic" pursuits (don't think coca cola is looking for quantum gravity experts :D). Obviously there aren't as many as condensed (at least I think), but I'm guessing they exist? I'm not currently in the US though (although I am a citizen and did my BS there) and don't mind moving to other countries for opportunities. I'm not sure if this is a game changer or not, but I think it increases potential opportunities, right?

4. Nov 19, 2015

### fzero

Yes, I tried to limit the hard numbers to academia since some statistics are available. I don't have hard numbers for government or industry. I would guess that they are not that large for government positions, probably on the order of <10% of the number of university positions and the difference in number between particle and condensed matter might not be large, since there are a number of national labs with particle theory groups.

Of course the number of theoretical particle positions in industry is ~0, but I have no idea how many theoretical condensed matter positions there might be, but agree that it is significantly larger than 0. I just don't know that it is large enough to compare with faculty positions.

In any case, you are wise to consider all possibilities. I hope that someone else here might have a more informed perspective on opportunities in industry.

5. Nov 21, 2015

### MathAmateur

Do what you find fun and interesting. Unless you become one of the small percentage of college professors, it will be the last time you have much influence on what you get to work on except in the gross. Don't waste it on something boring. You are probably just going to end up being a software engineer or the likes anyway ("hey Death, calculate the trajectory of that rock in frames 300-1300 in game 43"), but this gives you a chance to be a real physicist for a few years. You will treasure it.