Just yesterday, I came across a post from Jamie's Weblog Things I learnt during and about my PhD. Written by a computer scientists who didn't finish the PhD I find it somewhat overly cynical, but sadly enough there's lots of truths in it as well. So, since I guess some of our readers are struggling through these dark times while others are wondering whether to get into them in the first place, I want to add some thoughts from my perspective.
What is it good for?
A PhD is in the first line a degree that certifies you are qualified to conduct research. It's a necessary step if you want to stay in academia. It isn't impossible, but extremely unlikely that you will actually work on something groundbreaking. What you are supposed to do is to show yourself, your supervisor, and the rest of the world that you can study a topic in depth, acquire the necessary technical skills, formulate new questions, answer them, document them, and finish your examination.
You will likely not have a very good time. I don't want to discourage you, but I don't know anybody who was particularly happy during his PhD. As far as I am concerned it was possibly the worst time of my life. You will be mostly on your own, probably underpaid, overworked, be stuck on stuff you're not interested in while being subject to increasing pressure of getting done.
You will ask yourself repeatedly what is it good for. You will need a large capability for self-motivation. If you are not one of these persons who can not live without doing physics, a PhD is not for you. If you are stuck in the details of your thesis that nobody including you is or will ever be interested in, you will have to remind yourself endlessly: It isn't about changing the world or winning the Nobel-prize, it is a degree that certifies you are qualified to conduct research. Period. Read that reference. Make that figure. Finish that paragraph.
It is not that the topic of your PhD thesis is completely irrelevant. If you apply for a new job, people will look at the title. But there is the general sense that if it's rather dull that's not your fault so you'll be excused. The number of people who will actually read your thesis is tiny. As far as my thesis is concerned there's exactly one person I am sure read it. That's my mother. She corrected all typos and grammatical bugs.
What is far more important than the topic of the thesis is how you pursue it. The important information will be in the letters accompanying your first application. And that letters will either say you haven't managed to make one single step on your own, and were neither able to find the library nor to understand the wise words of your supervisor. Or it will say you're destined to be a future leader. Translate into: you haven't bothered your supervisor with questions he indeed had to think about. (Like, where is the library?)
You can increase the visibility of your thesis by putting it on the arxiv. You can decrease it by writing in any language other than English. My thesis is in German, but I put an introduction and a summary in English on the arxiv which by now has 42 citations - that is mostly because it contains a large collection of references and an overview on the field that at this time was pretty much up to date. Also, if you are working in a group, there is the chance that your thesis will be handed over to the next students as an introduction to the topic. I know various examples for that.
I want to quote a particularly amusing paragraph from Jamie's post
Supervisors: a curious species, rarely sighted in their expected habitat
Supervisors are strange creatures. Some are like ghosts, appearing occasionally for a fleeting moment, and you’re more likely to meet them at a conference than at the University. Others are always around but they’re too busy running around like demented hamsters on a wheel – all motion and no progress. They’re disorganised. All of them will, at some point, forget what your project is about – and some will even forget who you are.
I made an interesting discovery half way through my PhD: the number of good/useful/interesting/brilliant things that your supervisor will say to you is not proportional to the amount of contact you have with them – it’s constant. Yep, that right. You can have weekly meetings with your supervisor but you’ll only get three good suggestions a year out of them [...]
Supervisors also participate in a little-known game which can catch out the naïve student: Hunt the Supervisor. This involves the PhD student attempting to locate their supervisor during the agreed meeting slot. And, no, they are definitely not going to be in their office. You’ll be lucky if they’re in the right country.
This description is to my impression very accurate. I am relieved to hear actually it isn't much different in computer science than in physics.
There is something to learn from that: If you pick your supervisor, pay attention to his reputation in taking care of students and to his reliability, *not* to his professional reputation and his likability. Most obvious thing to do is chose somebody who doesn't already have more students than he can cope with, who isn't traveling 11 months of the year and who isn't glued to his BlackBerry. People who write books, speak on every conference, and are known for their public appearance typically aren't recommendable either. Problem is, these are the people you are most likely to have heard of. (And also the ones whose letters are likely to have the highest impact...)
You will find out these things rather easily: ask previous students. They will tell you more than you want to know. In some cases that information has already been collected somewhere and you can look it up. Nowadays probably online, in my days we had folders for every prof that were being passed around. What your found there was pretty accurate.
What helps if you're stuck in the dark times are friends, your office mates who are stuck in similar situations, and online group therapy. If things get really tough I recommend you get professional advice. Most universities offer a counseling service, anonymous and free of charge, where they will help you to move on. Whatever problem you have, you are very likely not the first to have it.
One possibility to relieve loneliness is to chose a topic that is close to something another student is working on. However, this is recommendable only if you will not be finishing around the same time. Reason is that you will for some years be referred to as "Soandso's student who worked on maggot growth" (or whatever) - "Which one?"
Besides this, if you are stuck on a supervisor who is essentially useless, do not focus on that person. Just face that he isn't going to help you and look for help elsewhere. This is easier today thanks to online connectivity. If you are smart and not lazy you will have no problem finding somebody who is willing to work with you. Typically these will be postdocs or young profs who do not have many postdocs and students, and are looking for people to work out details of some projects they have in mind. Both for my master's thesis as well as for my PhD I have been unofficially supervised by postdocs while the actual supervisors where constantly absent or kept forgetting my name.
In any case you should preferably look for somebody who will not be searching for a new job and be moving elsewhere in the soon future. That very often limits the usefulness of postdocs.
5 years after my PhD I am still amazed I ever managed to finish what looked like a complete mess only 6 months before my defense. If you are currently working on your PhD, I wish you good luck and don't lose your dreams out of sight.