Does the addition of a mildly impersonal recommendation letter hurt your application for grad school?

Question

For context, my field is physics and my situation is as follows:

I did an internship a couple of years ago in a branch of physics I don’t plan on going into. The main guy over the department, who brought me on, is a very well accomplished individual in his branch of physics, and while he was generally happy with my work there, I reported to someone else mainly for my time there, and so he never got to know me very well in a professional way. That being said, he was kind enough to offer to do letters of recommendation, and he has for internships I’ve applied to in the past.

Since then, I have developed much stronger relationships with research advisors who know me very well professionally, and I definitely plan on using them for letters of recommendation, but my question is as follows:

Does the addition of a mildly impersonal letter of recommendation hurt my grad school applications at all?

I imagine he tries in good faith to do as best as he can, but compared to other letters I’ll have, it may come across a bit generic, and I’m not sure if that carries implications with it that I can’t think of that would hurt the application at all. My first impression is that it wouldn’t have any negative effect, but I thought I’d ask to be safe.

Answer 1

An admission committee will have to make a decision based on the information provided. If the "well accomplished individual" offers you a letter of recommendation, it will presumably recite the facts. In your case, this will underline that you did an internship with him and that he likes you enough to offer writing letters. If I were on the committee, I'd rather have a letter like this than something that is so personal that I doubt that the letter writer is objective.

Answer 2

The best letters are likely to come from people who know you and your work well enough to say something specific about it as well as to predict your success. A letter from some luminary who doesn't really know you is actually something like hearsay evidence. The people evaluating your application probably recognize this.

If the letter is one among several (say, 3) then it is probably fine, but that isn't what is going to put you over the top.

But every case is different and some people write better letters than others. Ask a potential letter writer at your institution how they would advise in this case.

Note that letters not only need to describe your past accomplishments but also make a prediction about your future success. Those who know you well are in a better position to do both.

Letter writers should have some "standing" at the institution, also. Professors rather than lab managers, for example. But they don't need to be superstars. They need to be in a position to evaluate your likely success, meaning that they have gone through the process completely. Use letters from others only as necessary.

Answer 3

Whether you want the letter depends on the reputation of the letter writer. An impersonal letter from a highly accomplished and well-known scholar in your field can an exceptional addition to your portfolio of references because it shows that you can interact with researchers outside of your undergraduate department and are developing a research network, that you are probably capable of basic research, and that you know where the important questions are in the field. It also lends credibility to your academic pedigree, but you should not depend solely on this letter. Three letters are typically required. You need a personal letter from your academic/major advisor and whatever full-time professor you are closest to. Try to avoid letters from adjuncts, graduate students, or contract lecturers unless you are applying only to a master's program or a low ranked program. (This has to do with academic elitism, which is a problem, but a reality we live with)