I got along well with my undergrad advisor. He worked in QCD....30 years ago and switched over to quantum computation (not an area of interest). He has contacts, but none of them are working in related fields.
This is really good. The way academia is set up, you are much better off if you have access to a mentor. Be sure to renew contact with this person if you haven't been keeping in touch and let them know your long term goals, whatever they are (see below).
I’m open to researching anything, as long as it’s hep-th or closely related. Otherwise I don’t see a point: I wouldn’t be interested and it wouldn’t help with grad applications either.
I misunderstood your original goals (see next point). If your goal is a graduate program, then you don't actually have to do research in hep-th if you currently have zero research experience. I am not sure what your current CV looks like, but the wording of your first post implied that you did not do research during your degree. If this is true, then any research would greatly help you get into a graduate program, even if the research is not in hep-th. The point is to gain experience as a competent researcher, not to be an expert in hep-th (that's what grad school is for).
As for interest, hep-th is such a competitive field due to low funding levels, at least compared to other physics fields. I think the reality is that many people who want to attend graduate programs in this field will have to do what it takes to gain the skills and experience, even if it's not their main interest.
Frankly, the goal here is to get exposure and do some challenging research. Grad school would be nice bonus, but as I said above, I may not apply again. Not sure. So I’m not certain I should present grad school as the main goal in my emails. What do you think?
I guess I misunderstood. Sorry. In my mind, I thought the main goal of getting exposure and doing academic research was to continue in academia. Most of the time, taking on someone like you is a huge risk to the professor and will be stretching their funding thinly (i.e. it would take away from funding their own students). hep-th isn't really a field where people just hire researchers for the sake of doing research. My thought here is that a prof might be more willing to take this risk if they thought they could provide an opportunity to someone who might not otherwise have one.
To follow up on this though, if grad school is not necessarily your goal, then why are you interested in doing more research? Maybe if I knew your main goals/motivations, there can be more specific advice given?
I agree that emailing a large number of people is the best strategy. But wouldn’t I be spreading myself too thin? For example, if I picked 30 research groups, I’d have to familiarize myself with their work, which would amount to hundreds of papers. I think they’d be able to see through my emails. I’m having a breadth vs. depth problem here.
I think a balanced approach will work best. Perhaps there would be a few labs/groups you are extremely interested in and you would research them further. As you start finding people, you'll likely find opportunities that are more feasible/interesting. Spend more time on those. For others, you might be able to get enough information to craft an email from their research website and abstracts of a few papers.
It will certainly be a time investment---consider it a full time job (or at least part time in the evenings if you work a full time job to support yourself) looking for these opportunities.
That said, when I wrote the above advice, I didn't think that you would reach out to 30 groups. Typically, people who have graduated are working in another place and/or have other commitments/responsibilities. So, people generally contact research groups within their city or within driving distance rather than applying broadly all over the place. It might be helpful to be able to come into the department and chat with the professor before they "hire" you. In addition, it is not common to hire and pay someone to do this full time....you might end up with a 10hr/week thing, so it's not like it will pay all your bills. So if this makes sense to you, certainly spend more time focussing on these local opportunities rather than applying all over the country.
The exception is for advertised job positions---if you see them on the job board or HR website, then definitely apply.
But this is all personal. Maybe you are able and willing to just pick up and move to another place for an opportunity like this.
Finally, I have to ask: what do gap year students usually do when opportunities are so limited? Do they just pack up and become hedge-fund managers? Are you basically screwed once you exit an institution?
Sometimes people find work in a related field and gain experience/money before going back to academia. You're not screwed but it is certainly a lot harder to get back into academia once you are not connected with an institution. People often get back in through determination and perseverance and some sort of path like I described above. It's not the only way though.
Although most grad students come directly from undergrad, it's not that rare to find students who took time off. I know some students who took a much longer time off to pursue other careers or interests before applying to grad school. So, you're definitely not screwed!