At what age does breaking into academia as a professor, e.g. recent PhD / recent post-doc, in the United States become effectively impossible?

Is it at the age of 30 or 40?

I keep hearing about this from people who are at the very elite institutions, e.g. Harvard and Princeton.

I'm asking the question specifically for STEM subfields and for universities in the United States.

I am not only interested in what typically happens at the very top schools - I'm also interested in hiring at the less prestigious schools.

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    What do you mean by breaking into academia as a professor in the US? It depends where you are coming from. An established professor in, say, Canada could move to the US at essentially any age. – Thomas Aug 21 '18 at 6:35
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    When you say breaking into academia as a professor, what qualifications do you already have? PhD (recent or otherwise)? Post doc? Publications? Teaching experience? – astronat Aug 21 '18 at 6:36
  • @Thomas good point - please see my edit. – user93132 Aug 21 '18 at 7:03
  • @astronat good point - I've updated to specify recent PhD / recent post-doc. – user93132 Aug 21 '18 at 7:04
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    As I’ve heard it, the clock starts once you get your PhD. The numbers you’re hearing assume a PhD completed at the usual time. – knzhou Aug 21 '18 at 7:13

This is strictly speaking not an answer, since OP was asking about the US, but I felt sharing a European perspective may be of interest here as well. Flag if you feel I am straying off topic too much, and I will happily delete the answer.

ETH Zurich, presumably the premiere technical university in Europe (and one that often follows US procedure pretty closely), actually has an official policy on this.

The academic age of assistant professors (e.g. without the time period of maternity leave, industry experience, military service, etc.) should be 35 years or under at the time of appointment.


Note that they explicitly speak about "academic age", not biological age. Time spent as a postdoc counts against you, but time in industry or in maternity leave does not. Given that, there is (in theory) no biological limit to become assistant professsor if you have been doing "something else" before in your life, but I suspect in practice there is: at Swiss universities, there is mandatory retirement at age 65, and ETH presumably is not overly interested in investing into young professors that don't have too long until retirement anymore.

In Germany, a rule that I sometimes hear is that you need to become professor before the age of 40 or get out (where "professor" usually means W2 or W3 professor according to the German system). However, this is more of a guideline than a formal rule - I have certainly seen cases of people who got appointed with their first professorship after 40.

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    Maybe I (or someone) could ask a new question for Europe? – Allure Aug 21 '18 at 7:09
  • Yes and no. It sure helps that they largely follow organisational standards that rankings expect, but as somebody who has worked in Zurich and interacted with ETHZ on many occasions, I can assure you that it is in fact an elite place to do research. I would be hard-pressed to find a comparable institution in Europe. – xLeitix Aug 21 '18 at 11:58
  • I don’t understand. If "academic age" excludes any time not spent in academia after the PhD, why not specify at most five years of postdoc appointments (or whatever) instead of an "academic age" of 35? – Elizabeth Henning Aug 22 '18 at 2:21

This question is a bit unclear, but I'll try to answer as best I can. The question seems to ask about how age affects your ability to be hired as a professor.

TL;DR: While biological age is strongly correlated with factors that determine hireability as a professor, it is not itself a major factor.

For hiring faculty, the key question being asked is "what is this candidate's career trajectory?" and part of that is whether the achievements match up with the candidate's academic age. I believe it is illegal to consider the candidate's biological age in the US.

The key determinant of academic age is the PhD graduation date. A 25-year-old fresh PhD graduate has the same academic age as a 35-year-old fresh PhD graduate and both would be evaluated with more or less the same criteria. Obviously there will be some limit -- if your CV shows a 25-year gap between bachelors and PhD or that it took twice as long as usual to finish your PhD, people will wonder why.

The "red flags" will be things that have happened between the present and when you graduated. If there is a gap, that looks bad -- but could be explained, e.g., medical or parental leave. If you've spent more than 4 years as a postdoc, that looks bad (for computer science, in other fields long postdocs are normal).

Now if you already have a faculty or faculty-equivalent position, then things look different. You can be competitive for positions even 40 years after your PhD. However, after more than about 10 years from your PhD, you will need to apply for positions at the tenured level, rather than the assistant professor level. This means there is a higher bar in terms of a consistent research record and you will also be judged based on your record of teaching, advising, and funding.

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