At what age do professors stop taking new students?

Question

Assuming STEM, At what age do tenured professors stop taking new students?

I am a first year PhD student and have my eye on one professor who seems to be really interesting and I feel he finds me as a good candidate too but for some reason that he refuses to discuss he does not wish to take me in. Most of his current students are 1-2 years from graduating.

I have a strong reason to believe that it's his age (60-65). That's when I thought about the more general question I am asking.

Answer 1

There are no hard and fast rules for this. However, in general, the question is not so much time-after-PhD, but rather time before retirement. Most faculty advisors in the final stages of their careers stop taking students, so that they can wind their research groups down gracefully. Frequently, the last years before retirement will be spent writing and teaching, and mentoring a few additional students. The amount of time depends on the average career of a graduate student in the professor's particular discipline, but somewhere between three and seven years before retirement, the "wind down" will begin.

Answer 2

In general, I strongly believe that this depends on the professor and department in question. One imagines that there is a time that professors would like to stop taking students and a time that they actually stop taking students, and these do not necessarily coincide. In a small department where there are many graduate students and a shortage of advisors, presumably there is "peer pressure" from other faculty members to continue to advise students.

Answer 3

Sometimes people avoid taking students if they expect to retire or move before the student would graduate.

Answer 4

Whether or not one comes up with a number of years since PhD, since tenure, etc., for faculty to stop taking students, that is not the determining mechanism... except in a few cases where the cause is simply fatigue or disillusionment with the whole enterprise. But the latter seems uncommon.

Rather, the absolutely dominant cause is senior faculty' estimated time to retirement. Not only would it be bad to retire while one has a PhD student still in progress, but, further, it would be bad to retire while one has a former PhD student pre-tenure. Thus, taking on a student is approximately a 12-year commitment, at least, I think.

And, then, it becomes hard to clearly picture one's own energy level and frame of mind 12 years into the future...

Edit: as to why it might be bad to retire when one has a not-yet-tenured former student: very often, unless the student has taken a sharp turn away from the general enterprise of their advisor relatively quickly, the advisor will still be a leading expert concerning the topic. Even with the presumption that the advisor will be positive rather than negative, that opinion is important. If the advisor is retired, or is operationally retired, the expert-ness of their opinion, e.g., toward the future and future developments, is weakened, and their credibility in appraising future contributions of their former student is weakened. One wants to be visibly sufficiently engaged so that one's opinions are connected to current and future events, not only archival or historical or nostalgic stuff!

... and to have this presumably-positive, presumably-helpful letter simply due to retirement or disengagement is a loss that many could not afford. Nothing overtly bad happens, but one has lost a great deal.