Monday, August 05, 2013

Are physicists hot or not?

It has become trendy to study scientists. Two weeks ago, a group of network researchers published a paper in “Scientific Reports” that aims to analyze in how far scientists pay attention to what is trendy.


The title is however misleading for several reasons.

The most obvious reason is that the analysis presented in the paper was performed exclusively on papers published in the Physical Review journals (in the years 1976-2009), meaning the word ‘scientists’ would better be replaced with ‘physicists’. Even that would be misleading though, because it’s questionable that papers published in the Physical Review are representative for the whole of physics. Physical Review is a high quality journal and it tends to be conservative. If your research is speculative or on a highly specialized topic then it might not be your journal of choice, or so a friendly editor will write before marking your manuscript as “no longer under consideration.” Besides this, the sample also includes the “rapid communication” Physical Review Letters with the declared policy that topics have to be “of broad interest” -- clearly not representative for physics by large, if you excuse the sarcasm.

But to understand what the authors mean with “hot”, let us look at what they have done. They quantify the physicists’ ‘tracing’ of hotness by the probability that the subject of a new paper depends on the number of papers already published on the topic. Topics are identified by the PACS number of the paper (a paper can thus belong to several fields). If new papers are not evenly distributed over existing topics, but those topics with many publications already are more likely to attract new ones than random chance would suggest, this is known as preferential attachment. It’s more commonly known as the “rich get richer effect” and can be quantified by fitting a power-law to the distribution.

The authors find that the physics papers in their sample do show preferential attachment, ie who has will be given. The effect is not as pronounced as for some social networks (eg Flickr) where similar studies have been done, but it clearly exists. They have further looked at the scaling in subsamples broken down by the country of origin of the first author and done the same analysis separately for a selection of four countries: Japan, China, Germany and the USA. They find that the preferential attachment is the strongest for China, followed by Japan, Germany, USA. Yes, that’s right. According to this study, Americans are less likely to follow “hot” topics than Germans.

In the introduction of the paper the authors remark “It is believed among many scientists that there are many more Chinese scientists that are followers than original thinkers compared with many other countries.” I find this an interesting statement for a scientific paper, seeing that it’s little more than spelling out a perceived stereotype. Though they may be forgiven their bleak view of Chinese scientists since, for all I can tell, the authors are all Chinese, or are at least working in China. They interpret the results of their study as confirming this stereotype.

It should be mentioned that the sample which the authors analyzed also contains comments, replies and errata that I’d have thought should be mostly evenly distributed over topics. I would guess if these were taken out the sample, the overall effect would increase somewhat.

But is this preferential attachment a sign that physicists follow “hot” topics?

What this analysis actually shows is that Physical Review preferably publishes papers on topics that already have a literature base. I wouldn’t call that tracing of “hotness”, I’d call it conservative. If you wanted to quantify how eager physicists are to jump on ‘hot’ topics, you’d have to measure how likely new papers are to be in rapidly growing fields, as opposed to fields with many publications already. And to add my own perceived stereotype, I’d be very surprised if you’d find the Germans jump faster than the Americans.

In summary, this study isn’t uninteresting but the interpretation of the data is highly misleading.

26 comments:

Uncle Al said...

http://arXiv.org/abs/physics/0205089
Table at end of paper.

Negative temperatures kelvin hot - and not.

Robert L. Oldershaw said...


It would be interesting to see a graph of the incidence of the terms holography and holographic in the titles of papers posted to arxiv.org versus time over the last 10 years.

Rastus Odinga Odinga said...

There are many reasons behind the fad phenomenon, most of them obvious [need for cites to get tenure etc] and by no means all of them nefarious. What is new I think is that people are getting very very bored. There is a deep malaise among researchers in fundamental physics; to put it more simply, we are all bored stiff. So it is perfectly natural that when something new [or "new"] comes along, people will pile into it just to have something to think about that is less boring than exploring the far reaches of the supersymmetry parameter space or whatever. Hence the interest in things like firewalls. It's not such a bad thing: after all, while it's true that firewalls are not likely to lead anywhere, it's not like there is anything better to work on. And at least it provides exercise for the brain.

Stanley Marsh said...

Robert,
you might find the following graph of interest, it shows the usage of the words 'holography' and 'holographic' in arXiv papers since 1995: http://arxiv.culturomics.org/#?%7B%22search_limits%22%3A%5B%7B%22word%22%3A%5B%22holography%22%5D%7D%2C%7B%22word%22%3A%5B%22holographic%22%5D%7D%5D%7D

Best,
Stan.

MarkusM said...

"... each mathematician is a special case, and in general mathematicians tend to behave like "fermions" i.e. avoid working in areas which are too trendy whereas physicists behave a lot more like "bosons" which coalesce in large packs and are often "overselling" their doings, an attitude which mathematicians despise."
- Alain Connes -

Zephir said...

The Case against Public Science If we realize, that the actual findings and practical application come just from private research - if not garage scientists - (cold fusion) and the results of basic research rather conserve one hundred years misunderstandings, then I'm rather inclined to defund public science as a whole.

Phil Warnell said...

Hi Bee,

I don’t see what the problem is with researchers following hot topics. That is what I would imagine this has either the effect of having the truth of an idea finally flushed out, or to have it eventually beaten to death.

Regards,

Phil

Sabine Hossenfelder said...

Hi Phil,

I didn't say it's a problem, not sure why you think that. I said that the authors didn't test what they claimed they'd test. The following of hot topics is all well and fine and part of science and not a priori problematic. As with all things in life though, it's a question of balance. Problems occur when too many or too few people engage in it, and it's difficult to tell how much is too much and how little is too little. Best,

B.

Giotis said...

I think that the very basic misconception is that being a scientist is a job. Being a scientist is not a job; science is an endeavour. A scientist should be the ultimate individual, otherwise:

http://www.youtube.com/watch?v=b5lMLj76Zi4

Plato Hagel said...

Bee:I said that the authors didn't test what they claimed they'd test.

I think the demands held by any phenomenology would seek to find that balance. I really do not see anything wrong with that either.

There are reasons why there is a theoretical attach to any research. I think most understand that, and that what is needed is what is required from the possibility of finding a way to test currently within experimental frameworks.

I like your link and quote MarkusM from the work of Okun and Connes respectively.

Best,

Sabine Hossenfelder said...

Giotis,

Whose 'misconception' are you referring to? Most of the people who publish academic papers live from the salary they get for doing their job. Yes, I would agree that being a scientist is more than a job, but scientists also have to eat and sleep and pay the rent. I've said many times previously on this blog that the larger the existential pressure on scientists, the more the process of science will be skewed because it affects people's reasons to select one topic over the other. Seen from the perspective of competition and survival, most of the trends you can see in academia aren't very surprising. They can be problematic however for the progress of science at large. Best,

B.

Phil Warnell said...

Hi Bee,
I didn't say you said researchers who follow hot topics are a problem; rather to indicate this being what is implied by the study’s authors. My point being is their whole premise is groundless to begin with for the reason which I stated. Further I don’t see the journals having the function of providing balance to what is being studied, rather they simply serving as but one of the conduits through which the scientific methodology(s) and process carries itself out; as after all if the journals themselves knew what the correct directions were we wouldn't need the scientists to begin with.

“Science is an essentially anarchic enterprise: theoretical anarchism is more humanitarian and more likely to encourage progress than its law-and-order alternatives.”

- Paul K. Feyerabend, ”Against Method” p-9

Best,
Phil

Sabine Hossenfelder said...

Hi Phil,

Sorry for the misunderstanding.

With regards to journals, they serve a much more important function in the community than being a conduit for exchange. The reason is that peer review is still mostly provided by journals. Since scientists often need a proof that peer review has taken place, journals publication is crucially important. It is unfortunate, though understandable, that many journals hesitate to publish papers that do not fit into presently existing categories. It's this conservative bias that I think the study in this paper actually shows. As I mentioned in my post though, Physical Review might, in this regard, not be very representative for the field as a whole.

In any case, this conflation of publication issues with peer review is why I think we'd all be better off if peer review would be conducted independently of journal publication. Best,

B.

Giotis said...

Dear Sabine,

You simply can’t choose a topic to work on based on whether you can make a living out of it. Then you should not be a scientist and do something else. Being a scientist has a moral obligation towards the truth. If you can’t make the commitment then you should quit.
BTW did you like Bukowski’s video? I think it’s very appropriate in the sense that being a scientist should not be considered as a 9 to 5 job.

Bob Frey said...

Hey! I got here reading a review of 23andme that was fabulous. But now I want to know what is a "supersymmetry parameter space?" It sounds pretty sexy to me. Is that hot?

Robert L. Oldershaw said...


"supersymmetry parameter space" is an infinite baking sheet of fudge.

Alas, no pearls of wisdom in it but you can call it as "hot" as you like.

Uncle Al said...

@Robert L. Oldershaw N points are modeled with at most N-1 parameters. SUSY needs more (pdf). String/M-theory, quantum gravitation; SUSY, dark matter; solar axions, and proton decay all assume exact vacuum achiral isotropy toward matter. All suffer parity violations and chiral anomalies then patched with unending symmetry breakings. Take the hint.

ECKS gravitation allows vacuum chiral anisotropy. An Eotvos experiment opposing two 20 gram sets of single crystal alpha-quartz test masses, space group P3(1)21 vs. P3(2)21, opposes 6.68×10^22 enantiomorphic unit cell pairs (opposite shoes). Repair a subtly defective physics founding postulate within 90 days, as Bolyai expanded Euclid.

Plato Hagel said...

Maybe try this link Unck.

Uncle Al said...

MSSM adds 120 new parameters. Peskin offers how many new fits? Run my experiment and you know: zero parameters, zero wiggle room, classical theory already in place.

Composition Eötvös experiments have the differential property on both sides. Less than 1/420 of loaded test mass is active mass. A field (polarized electron) Eötvös experiment has less than 1/20,000 active mass - perfect Mn(2+) undecatiplet without a counterion. A geometric Eötvös experiment is at least 0.9997 active mass - relative nucleus positions in a crystal lattice. PSR J0348+0432 binary, Physics Today 66(7) 14 (2013), discovered nothing new within experimental error. Every observable exactly cancels except geometry with space group P3(1)21 vs. P3(2)21 single crystal quartz. A net non-zero signal cannot be denied. It sources chiral, parity, symmetry violations; the Tully-Fisher relation, biological homochirality; and fuels cosmic inflation (false vacuum pseudoscalar decay) to allow only one of matter vs. antimatter. It kills stringy, loopy, foamy, bubbly, and braney quantum gravitation, dark matter; SUSY, solar axions, and proton decay. That’s pretty good for 90 days on bench top in existing equipment. You get eight gold-plated souvenirs, too.

Zephir said...

/* run my experiment and you know: zero parameters, zero wiggle room, classical theory already in place */

LOL, you cannot mean it seriously.. Do you really believe, that the single experiment with pendulum can solve all problems of contemporary physics?

Phillip Helbig said...

I thought you were referring to scientists themselves being hot.

Google "dr. december peanut butter elvis rocky" (without the quotes). Don't ask.

Phillip Helbig said...

http://www.independent.co.uk/news/science/bums-biceps-and-bunsen-burners-1323140.html

Phillip Helbig said...

Look here!

Sabine Hossenfelder said...

Hi Giotis,

"You simply can’t choose a topic to work on based on whether you can make a living out of it. Then you should not be a scientist and do something else. Being a scientist has a moral obligation towards the truth. If you can’t make the commitment then you should quit."

It is totally irrelevant what you think people "should" do. As a matter of fact many people, scientists included, do pay attention to whether the topic they work on will feed their families, now and in the future. Scientists are, in the first line, human.

Look, it's not that I disagree with your ideology. What I am saying is that if you want it to be reality, you need to set up the system so that it doesn't conflict with human needs. And that presently isn't the case. When forced to chose between "moral obligation" and paying the rent, most people will pick the latter. That's reality and that's a problem for science that isn't presently properly addressed. Best,

B.

Sabine Hossenfelder said...

Phillip,

Well, the post was a criticism on 'misleading titles' so you misread it correctly, if that makes any sense.

I did the googling. Interesting fellow. Now the second hit is this blog... Best,

B.

Giotis said...

Well you know what they say:
Long is the way, and hard, that out of hell leads up to light.
Scientists should walk this rough path though in my opinion. Thank God I’m an engineer and I don’t have such moral dilemmas. We just follow the money :-)