Physics Demographics

To some extent, if one wants to understand some of the recent history of physics, one should take into account important demographic trends in the subject. For particle physics in the U.S., in recent years the Particle Data Group has been conducting an annual Census of U.S. Particle Physics. The American Institute of Physics has a collection of reports available on-line. The NSF and other various other organizations periodically issue hysterical reports about there being too few physics students getting Ph.D.s. For some perspective on this, in 2003 there were a bit more than 1100 physics Ph.D.s awarded in the U.S., and during 2001-2002, about 230 retirements per year of permanent faculty. Due to large recent increases in graduate student enrollment, the number of Ph.D.s is expected to increase significantly during the next few years. There doesn’t seem to be much danger that anytime soon U.S. universities will see any change in the current situation of having vastly more qualified candidates for academic jobs than actual permanent jobs available.

In the specific case of particle theory, the Particle Data Group figures show roughly 450-500 tenured faculty, and 400-450 graduate students. So, the entire U.S. tenured particle theory professoriate could be just about replaced by one 4-5 year cohort of graduate students. The theoretical particle physics job market will remain extremely competitive for the forseeable future.

Unfortunately, the main hope for young physicists who want an academic job is that current tenured faculty are getting old and have to retire or die sooner or later. The latest data I’ve seen (from a 2000 AIP membership survey) indicated that the average age of tenured physics faculty had reached nearly 60. If anyone knows of more recent data I’d be interested to hear about it. I don’t know of any good on-line sources for historical data, but the December 1995 issue of Physics Today had an interesting article about demographic trends in physics entitled “What future will we choose for physics?”. The authors of that article claimed that before 1970 the median age of physics professors in the U.S. was relatively stable and under 40. In 1970, the number of physics Ph.D.s awarded hit an all time high of nearly 1600, and faculty hiring essentially fell off a cliff. According to the Physics Today article, from 1970 on the median age of tenured faculty increased linearly at the rate of about 8 months/year.

One effect of the aging of the physics community is that Physics Today has been running an increasing number of obituaries, since it has a long-running policy of printing a picture and several paragraphs about each of their members for whom obituaries are submitted. As of this month, facing the prospect of having to devote an increasing fraction of space to this purpose, they have abandoned this policy, announcing that from now on they will only publish obituaries in special cases, setting up a separate web-site for on-line obituaries, since these won’t be appearing in the magazine itself.

Update: Andre Brown wrote in to point out that the 1995 Physics Today article is available on-line.

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38 Responses to Physics Demographics

  1. blank says:

    I think the main hope for young theorists hoping to get an academic job, is some sort of natural disaster at the location of one of the big Strings or SUSY summer conferences.

  2. Andre says:

    “What future will we choose for physics?” is available online along with some other career related articles on the physics today website:

    http://www.physicstoday.org/pt/vol-54/iss-4/archive.html

  3. Chris Oakley says:

    These statistics are even more shocking than I expected.

    I am not saying that I have all the answers to these problems (not in detail, anyway), but it is useful to examine some of the significant events in our subject. Off the top of my head … Gell Mann discovered the eightfold way at age 23; Einstein, photoelectric effect & SR, aged 26; Heisenberg, matrix mechanics, aged 25; Dirac, the relativistic wave equation, aged 26. De Broglie, wave-particle duality at 24 (or thereabouts). Schrodinger, an old man at 38 – mind you, he was only following up on his young student de Broglie’s work. <shameless plug> Also, my great uncle W J van Stockum, Axially Symmetric solutions of Einstein’s equations – the work was done before he was 26 – it is still regularly cited &lt/shameless plug>

  4. Chuck says:

    And, yet Edward Witten just announced on PBS’s show, Nova, that he did his best work in his 30’s and 40’s.

  5. SteveM says:

    “Science advances funeral by funeral.”
    Max Planck

  6. blank says:

    Perhaps next time some billionaire philanthropist wants to help advance physics, instead of spending $100mil on some fancy new research center, he should offer $100mil in incentives for 50- and 60-something professors to retire early.

    Granted, it’s not as sexy as having a building named after you.

  7. JC says:

    Is there a specific reason why physics funding fell off a cliff around 1970? From what I read over the years, it seems like the government decided to stop funding a lot of things in the early 70’s, such as the Apollo missions.

  8. woit says:

    JC,

    From what I remember it was a combination of a bad recession, putting an end to somewhat of a bubble in research and academic spending. Throughout the 50s and 60s the economy was expanding, and especially after Sputnik in 57 ever larger amounts were going into funding research and expanding the size and number of universities. When the recession hit, and state and federal spending had to be cut, the universities and research funding were among the hardest hit. Since universities had just expanded greatly in size and hired a lot of new tenured people, when all of a sudden they stopped expanding there were virtually no jobs, since the faculty was so young that very few older professors were retiring. This effect has continued for much of the period since 1970, only starting to change recently as many people hired during the 60s are finally starting to retire.

  9. A.J. says:

    Gell Mann discovered the eightfold way at age 23; Einstein, photoelectric effect & SR, aged 26; Heisenberg, matrix mechanics, aged 25; Dirac, the relativistic wave equation, aged 26. De Broglie, wave-particle duality at 24 (or thereabouts). Schrodinger, an old man at 38

    Yeesh. What’s the point of retelling this myth about young genius? That we should drive established thinkers out of academia? Or maybe that we should refuse to hire anyone who’s done great work before the age of 30, on the grounds that their best years are behind them? 🙂

  10. D R Lunsford says:

    On a recent visit to ‘s physics department, I saw among the grad students and postdocs, not a single American face. Mostly Chinese, a smattering of Russians, Indians, and Pakistanis, a token German or two.

    This is the direct result of the Faustian bargains struck among American deans and registrars, and those who desired wonder weapons. In the US, physics is done for power or profit, not for knowledge. Physics = weapons.

    -drl

  11. weichi says:

    This is a bit off-topic, but being outside academia, the whole idea of tenure seems a bit odd. As I understand it, the idea is to give talented people the freedom to work in unfashionable/unpopular areas. This sounds great, but given human nature, how realistic is it to expect this to lead to improved results? Are there a lot of scientific results from, say, the past 50 years that were achieved by tenured professors, but would likely *not* have been achieved if tenure did not exist?

    Maybe Andrew Wiles & Fermat might be an example, though that’s not really science.

    Perhaps my question boils down to this: I understand the benefit to professors of tenure. But what is the benefit to universities and to society at large?

  12. Doran says:

    There is some statistical correlation between ground-breaking work and how young a scholar is, though that is no reason to ship 40 & 50 year-olds off to the old folks home just yet. For those of us (myself only 21) still yet to turn 30, the young genius motif is even more frustrating because we only have those few years left before our brains turn to mush, though I imagine this isn’t the care.

    What is the most important characteristic of the giants in any scientific discipline is the ability to think differently. To head off the reservation and still keep your wits about you. Yes it may sound like a worn out platitude but it still makes sense. Just have to think outside of the ten dimensional box is all.

    Being an undergrad in physics & history, I ended up being interested in the history of scientific theories and the many curiousities that abound in that study. Does anyone still do research along the lines of John Bell and hidden variable theories? I would really love to hear a physicist actually discuss this subject rather then snear at it for being “too much philosophy.”

  13. Chris Oakley says:

    On the age issue, what I think can be changed is the emphasis. At the moment the most important thing is that a group of middle-aged and old men (the tenured professors) should have secure – if relatively poorly-paid – jobs. Demonstrably, this group is not the one most likely to be of most benefit to the subject. This is something that falls, in the vast majority of cases, to the under 30s. The emphasis could be changed so that the latter group is allowed more free rein. This would of course be at the expense of the old timers, but I simply do not accept that university professors are unemployable elsewhere. The bottom line is that they can always become schoolteachers (which would be some kind of poetic justice given how many of their graduate students will have had to find employment in this profession aged about 24).

    Here is the kind of thing I would like to see:

    (i) No tenure (at least not in research posts)
    (ii) Research jobs/grants awarded on a 5 year rolling basis
    (iii) Decisions about allocation of jobs and grant money made democratically, involving all engaged in research, i.e. from 2nd year graduate student upwards.

    This is not ridiculously ageist anyway, as someone who continues to be a good researcher into their 30s and 40s is likely to continue to be re-elected to their research post.

    The point is simply that, as history has shown, the young person’s scepticism is the most valuable thing that science has. Instead of treating this as a dangerous threat (as happens at present), it ought to be harnessed and used in ways that actually advance the subject.

  14. Nigel says:

    With all due respect to them, a few words about the influence of Susskind, t’Hooft, and Hawking. Although Hawking radiation is undoubtedly a major contribution, Hawking has possibly made a couple of crackpot errors elsewhere. First, his application of Penrose’s black hole math to the big bang, which seems to ignore the possibility that gravity might have a mechanism within the universe. Second, in 1976 he published ‘The Breakdown of Predictability in Gravitational Collapse.’

    This was taken seriously by Dr Leonard Susskind and Dr Gerard t’Hooft who were in the audience of Hawking’s talk on the subject a few years later in San Francisco. Susskind is quoted in some BBC documentary saying that the lecture shocked him into believing that the Hawking ‘breakdown of predictability’ completely threw causality out of physics! Then in July 2004, Hawking announced he was wrong all the time…

  15. Thomas Larsson says:

    On young geniuses. Older people are usually better in normal science than youngsters because of their greater experience, but too much experience is a disadvantage when new thought patterns are necessary. Of course, people who did successful radical thinking in their youth can do great conventional science when they grow older. Just think of Dirac’s wonderful work on constrained Hamiltonian systems, done at an age close to 60.

    Witten is no counterexample. He was 33 when he, for better or worse, pulled the physics community through the first superstring revolution, and many others who jumped the string bandwagon were even younger. And most old-timers who did become string theorists, like Susskind, Veneziano and Gross, had once done dual resonance models or S-matrix theory, so they didn’t really have to think in radically new ways. That Witten kept doing original mathematics for many years afterwards does not change this. He seems to have slowed down in recent years, though.

    What 33-years-old today could, like Witten in 1984, change the direction of theoretical physics? Lubos Motl? 😉

  16. Chris Oakley says:

    Thomas,

    We will perhaps never know what today’s generation of youngsters engaged in particle physics research are capable of. At least, not as regards physics. Since the majority have been duped into believing that following the Superstring bandwagon is the only thing likely to be of any benefit to their careers, and since – on their own admission – this is still all light years away from actually being physics, we will never know what they might have achieved.

  17. Arun says:

    First, youthful creativity is most pronounced in mathematics and theoretical physics. This criterion should not be used in other areas where it is less true, for instance, great experimentalists have done crucial experiments at more advanced ages (and physics is primarily an experimental science, the discussion here shows that people say it a lot, but pay lip service to it, behaving as though Hawking and Witten and Einstein is all there is to physics).

    Second, many of the breakthroughs wouldn’t happen without the plodding work of actually dealing with messy reality. Who is going to do the actual work of measuring and building the enormous set of experimental results which are the bulwarks of theory?

    Physics needs a balance of people – mess with that balance and you’ll destroy the enterprise of physics.

  18. Not a Nobel Laureate says:

    It’s certainly a truism that Physics is an experimental science. Pure reason will get you “proofs” like Hegel’s that there can only logically exist seven planets.

    However, given the how the number of HEP expertiments has concentrated over the decades,
    the usual suspects are still in charge.

    Making bricks for the Pharoah, waist deep in mud and straw, is probably a better career choice.

  19. Dissident says:

    Doran, re. hidden variables, there’s always this “old” guy:

    http://www.phys.uu.nl/~thooft/

    (scroll down to where he brings up “Fundamental aspects of quantum physics”, check out the publications). His take is that both QM and GR will have to be modified in order to be reconciled. My own half cent’s worth is that he’s on to something. Penrose may or may not agree; his view seems to be more along the lines of QM, but not necessarily GR, being in need of revision.

    Arun, ” the actual work of measuring and building the enormous set of experimental results” is always going to be carried out by the same sort of people who’ve always done it: technicians, starving grad students and post-docs barely scraping by.

  20. Stephen says:

    Is anyone sure the supposed superiority of young physicists isn’t just an example of regression toward the mean?

  21. Not a Nobel Laureate says:

    Always a pleasure to read about Physics

    http://www.eurekalert.org/pub_releases/2005-10/jhu-neh101705.php

    as an antidote to the Meta-physics of strings.

  22. Nigel says:

    QM and GR: the “stupid” physicist may be at an advantage in spending more time on this stuff, when brighter students are getting stuck into the delights of renormalised QED and ST.

    “Dissident”, are you sure that QM and GR need modification? Could be the maths is fine but GR can’t be applied to cosmology (universe) because there is a gravity mechanism within the universe. This keeps GR maths intact, and perhaps makes the maths more clear physically.

    As for QM and QFT, we know the fabric of space is filled with virtual particles. Normally particles like gas molecules can’t carry transverse waves, only a solid normally allows transverse waves. But suppose the virtual particles have a spin, like real ones? Then you get transverse waves. Dr John Baez has some ideas on this for quantum gravity here http://math.ucr.edu/home/baez/loops05/ which seem to account for the light speed of gravity while preserving a pressure mechanism?

    My understanding is that this is reinventing the wheel, since Maxwell’s 1873 Treatise section 822-3:

    “The … action of magnetism on polarised light [discovered by Faraday not Maxwell] leads … to the conclusion that in a medium … is something belonging to the mathematical class as an angular velocity … This … cannot be that of any portion of the medium of sensible dimensions rotating as a whole. We must therefore conceive the rotation to be that of very small portions of the medium, each rotating on its own axis… The displacements of the medium, during the propagation of light, will produce a disturbance of the vortices … We shall therefore assume that the variation of vortices caused by the displacement of the medium is subject to the same conditions which Helmholtz, in his great memoir on Vortex-motion, has shewn to regulate the variation of the vortices of a perfect fluid.”

    Am I alone in thinking we are going round in circles here?

  23. Quantoken says:

    Peter:

    You described some observation of facts that we all know already. But what’s your point? Are you saying it’s a good thing or a bad thing? Are you complaining about something you don’t like?

    Yes it’s going to be hard nowadays if a young man wants to get into an academic position and study physics. But is that a problem? I don’t think there is any problem at all. We have a quite adequate number of physics professors teaching in universities, and actually, if anything, maybe a little bit too many of them, and if there is any shortage of professors, we can quickly replenish from freshly minted graduates. So what’s the problem?

    If a young man wants to become a physicist and he can’t because the society doesn’t need any more phycists than what it already has, then that’s not a problem of the society, it’s a problem of the young man himself. There are too many important things in the world that needs some young intelligent men to work on, so there could never be an over-abundance but shortage of the suply of real talents.

    A while ago Mark Troden complained about the fact that not all of his students can get a faculty position, and he thought that’s bad. I showed to him that if he educated just 12 students and each all becomes a faculty, and each of them also each educates another 12 students who all become physicists as they wished, so on and on. Then the simple math shows that the multiplication took less than 9 generations to exceed the earth’s population. Such exponential growth is simply not possible.

    So I told him a realistic expectation is he should expect at most one, and probably zero, of his students who could eventually become a faculty, and the rest evaporate, regardless how many students he put out, and regardless how hard his students work.

    Quantoken

  24. Thomas Larsson says:

    QT, the physics community grew exponentially for almost century. In the US, the PhD production rate grew from about 1/year in 1870 to 1,000/year in 1970. It is unlikely that such a growth rate is sustainable for another century.

  25. Dissident says:

    QT, the problem is that physics professors are supposed to do two things: teach and research. As you point out, there is no major problem as far as the teaching goes. But if it is true that most breakthrough research is done by young people, the current situation with faculty averaging 60 means that breakthroughs are heavily disfavoured. This demographics is a a recipe for stagnation. And it does indeed seem to work pretty well…

  26. Somebody says:

    There is a saying that groundbreaking work seems to be mostly achieved by young physicists (say at age X), but on the other hand, if you look at any single, given physicist, his or her “best work” tends to be done at an age significantly greater than X.

    It’s population bias.

    There are vastly more people in their 20s and early 30s working in particle physics than in their 40s and 50s, so it stands to reason that the former group produces a large fraction of the best work. On the other hand, they also produce a lot of not-so-great work, too, but those that do don’t usually stick around into their 40s and 50s.

  27. Dissident says:

    Somebody wrote:
    if you look at any single, given physicist, his or her “best work? tends to be done at an age significantly greater

    Maybe true of average physicists. Definitely not true of the true standouts like Newton, Maxwell, Einstein and the QM crowd.

  28. Paul Houle says:

    Senior physics think that a tight market for young physicists means they can skim the cream of talent. The reality might be the opposite: a bright young person who wants a career in science should choose any field BUT physics. Young people who stumble into graduate programs of physics today are the most clueless people about opportunities in science — the “gauntlet” doesn’t select for the best people, but just for people who can take the most abuse.

  29. Dissident says:

    Paul, I remember an interesting piece of statistics from a few years back (maybe it’s from the “What future” article?) showing that the fraction of top undergraduates in physics who choose to go on to grad school (in physics) has been declining since the 70s.

    Nobody in the real world would be particularly surprised; it’s a well known fact of business crises that the best people are the first ones to leave. They have the brains to see what’s going to happen and they have the ability to find other lines of work. The last ones to leave are the clueless and those without alternatives.

  30. Doran says:

    Paul, pray tell how these physics undergrads are clueless of other opportunities in science, when we have been hearing about the horrible job market for academics in physics and watch our friends in biochemistry, engineering, and computer science pick up high paying jobs doing industry research for years. Also, why are departments still encouraging those who actually want to go to graduate school in physics despite more lucrative options in other fields.

    Now physics is hard, and I can attest that the undergraduate curriculum does resemble a weeding out process, but thats how all the sciences at a top-level school are like. And who stick it out, those with the skills and the determination to master the material. Dissident, the first ones to jump ship are often those who came in thinking physics was easy and got a rude awaking.

    I must admit my grades are not stellar, but I cannot help but feel a bit miffed by this. I believe most physics students who decide to go to graduate school are fully aware of the limbo that awaits them, but never-the-less are drawn to an intense and rewarding study of physics. To degrade that desire is only hurting the field, by dissuading anyone from even considering the subject to begin with.

    I must agree with QT, that if one cannot find employment in academia, there are numerous other avenues that need intelligent technically trained individuals. My personal point is that maybe it would be better to encourage those interdisciplinary connections as well as the rigorous physics studies, rather then accusing the next generation of researchers as being adrift without a clue.

  31. Quantoken says:

    Doran asked: “why are departments still encouraging those who actually want to go to graduate school in physics despite more lucrative options in other fields”

    Physics departments NEED to recruit and train large amount of graduate students, regardless whether the academy community needs that many new Ph.Ds or not. That’s what university departments do and that’s how they get fundings and survive at all. Can you imagine a Harvard physics department which no longer admit any graduate student for the next 10 years? Or can you imagine that Mark Troden trains just one student of his, instead of 12, knowing that the realistic expectation is at most one of his students can one day become a faculty? No he can’t. Training students is part of Mark Troden’s job that he gets paid for. So he will continue to train as many as he can, regardless of how his students will end up be.

    It’s like a fish would lay a couple million eggs at a time, most simply got eaten up by other fish and the realistic expectation is only one egg out of the millions will grow up to an egg-laying fish. Would a fish then lay less number of eggs so as not to be wasteful, or not to feed its enemies? No, a fish will still try to lay as many eggs as it can. Just like a physics professor will always try to train as many students as he can.

    It’s all Darwinism whether it’s the nature or the human society.

    Quantoken

  32. Thomas Larsson says:

    Chris,

    Gell Mann did not discover the eightfold way at age 23. He was rather something like 33; I think he was born in 1927. Maybe you thought of the Gell-Mann and Low theorem from 1953.

  33. Chris Oakley says:

    Hi Thomas,

    According to this:

    http://www.answers.com/topic/murray-gell-mann

    He was born in 1929 and invented the Strangeness quantum number (not the Eightfold Way as I originally said) at the age of 24.

    Well, I did say that the information was off the top of my head.

    Somebody called “Somebody” pointed out that the majority of people engaged in research are in fact quite young, i.e. PhD students and post-docs. This may be true but they definitely do not have the whip hand. Their relationship with the relics who actually run their departments is more like Apprentice/Jedi Master, and my point is simply that this is completely wrong, as the young person is the one who is far, far more likely to come up with the goods provided that he/she is given the space to do so.
    I have to be honest here – my D Phil (PhD) supervisor (between 1982 and 1984) was great about letting me do what I thought best. The problems only started to arise when I wanted to do post-doctoral work. At that point the old timers were able to demonstrate the consummate ease with which young, dissenting voices could be silenced.

  34. Dissident says:

    Sorry Doran, but you’re looking at this from an undergraduate’s perspective. The old guys contradicting you have been where you are now, and well beyond.

    Sure there’s a always a whole bunch of fresh undergrads going into physics, finding it too hard and “jumping ship”. I don’t think anyone (other than you) taking part in this discussion ever considered them. They really don’t count. The people I and the other oldies here are writing about are those who do graduate; in particular, the top of the class.

    I can not underscore enough what Quantoken already told you: physics departments run on grad students and post-docs. They are extremely cheap labour who do everything from teaching labs and correcting homework to doing the actual research which professors put their names on. This system is in essence the medieval one of apprenticeship. In modern terms, it’s a system of exploitation, by the old of the young.

    As if that weren’t enough, funding also tends to be directly related to the number of students. If you can demonstrate a large demand for whatever it is that you teach, you will get more funding; if you can’t fill all seats, you will see cuts and eventually be forced to fire faculty, maybe even shut down the whole department.

    If you understand all this and still want to try for a “career” in academia, you have admirable guts and may even deserve to be cheered on. But do not delude yourself about what you’re up against.

  35. weichi says:

    There seems to be a subtext here that physics is a particularly poor choice for people who want to go into science. But are job prospects in other fields of science really that much better?

    My guess is that in academia the situation is no better, but there are more opportunities in industry for other fields – biosciences in particular, perhaps also for chemistry? Does anyone have any numbers for other fields?

    We should also keep in mind that for certain fields of physics, there will never be job opportunities in industry. My understanding is that industry hires condensed matter experimentalists to do work that is at least similar to academic research in condensed matter, but I’m sure that no one gets hired by industry to do theoretical research that is similar to string theory. So choice of field within physics also has an effect, perhaps a large one.

  36. D R Lunsford says:

    About age: I suspect every physicist has (at least) one good idea, and when this shows up is not a function of age, rather insight (a combination of experience, technique, and intuition). And, one may have a good idea, but not realize for years. Certainly intuition is highest when inexperienced, because you don’t know what you can’t know!

    So it’s more like a Heaviside function, theta(X – age) where X is when you have your idea, and age could be anything between diapers and senility.

    -drl

  37. Not a Nobel Laureate says:

    Anecdotally speaking.

    It’s unfortunate that the culture in academic physics is such that any other path than the academic one leading to a professorhips is seen as failure when the reality is that that most graduates will go on to do something else – the few perceptive ones by choice, the rest by default – often with considerable, but pointless, bitternes.

    I’ve met many exceptionally bright people outside of academic physics – sorry to say, but these days the best and the brightest are no longer in HEP. HEP today “reads better than it lives”.

  38. Eli Rabett says:

    A bit late, but a short comment on why the job market in physics dropped dead in the early 70s:

    1. The costs of the Vietnam war, amplified by a recession limited the Federal budget for research

    2. Universities that had been expanding like gangbusters to meet the demands of the baby boom, found there was a baby bust.

    3. New universities established to meet the growth in enrollment (e.g. UMass Boston as one example) had hired complete departments of relatively young faculty in the mid-sixties, but then hired no one else for thirty years. This cohort is now retiring.

    From one who was a bit late.

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