# Too focused on theoretical physics? Or how come there is so little experimental physics being asked here?

The vast majority of topics in this SE seem to be either school/college course related (i.e. with no relation to experimental practice) or academic topics related to all sorts of theoretical physics.

From my personal experience at many universities and research centers, the staff working in experimental physics departments greatly outnumbers those in theoretical physics, so I would expect much more focus on experimental questions in a general "physics" exchange.

I am wondering is there a separate SE aimed at experimental physics or how come there is so little experimental physics being asked here?

Update:

based on initial discussion here a further interesting and related question is: "how can we improve this site's accessibility where experimental physics is concerned?" (quoting Daniel Sank)

• – Qmechanic Mod
Dec 26, 2021 at 23:21
• @Qmechanic So does that mean (assuming nothing has changed in the past 7 years) that physics.SE is not exclusive for theoretical questions and that there merely seems to be a notable desinterest of experimental physicists to the site? Dec 26, 2021 at 23:28
• What kind of "experimental physics" question are you looking for? E.g. 'how does the LHCb hadron calorimeter work', or 'what's the best practice to inject a tapered amplifier'?
– SuperCiocia Mod
Dec 27, 2021 at 5:39
• @SuperCiocia both would be on-topic but I still guess the second one is what I miss in particular. The first one is rather broad ans can also be answered with a bit of google, but the second one benefits greatly from handson experience of fellow experimenters. Dec 27, 2021 at 6:02
• Another distinction is that questions regarding large scale equipment such as LHC can easily be answered by colleagues at the site. Condensed Matter physics and the like, where researchers often work alone on a project are more often that not in a scenario where there is noone to provide expert suggestion in the same group Dec 27, 2021 at 6:13
• I think there is (was?) real bias in that some experiment-oriented questions have been closed as "off topic" because they're "engineering". That bias concerned a number of users and lead to the meta post linked in Qmechanic's comment above. Note that the meta post specifically links to a question about making a piece of lab equipment more quiet which was closed as off topic.There is an accepted answer, which suggests that we should not close such questions. Dec 27, 2021 at 18:09
• Why do you say experimental physics is underrepresented? I mean, we can't represent a branch of physics proportional to the number of people that work in it. As a Q&A site, we can only represent it based on its content of knowledge. But maybe I'm missing something. Why don't we do a sanity check in our heads here: Come up with a list of things in experimental physics you could imagine being the subject of a well-received question here. Then come up with a list of theoretical physics questions. What's the ratio? Is that reflective of the actual ratio we have? If yes, what's the problem?
– Jim
Jan 11 at 15:42
• I mean, just keep in mind that physics is about the theories and concepts. Experiments attempt to test those theories and push limits, but experimental practices and techniques aren't as varied as the independent topics within the theory side. Experiments from one branch of physics will largely have the same techniques and methods as those from another. And after all, this isn't the study of scientific experimentation, it's the study of physics. The amount of topics in one will vastly outnumber the other.
– Jim
Jan 11 at 15:49
• @Jim your comments have the same sentiment as the other (now deleted) answer: experimental physics is more of the same anyway, there are not so many details people could ask questions about. And I will reply in the same way: Frankly, such a proposition displays some ignorance. However, I believe my mistake was in counting professional physicists. If you include all the pupils and students (who only do theory for the most part), there are indeed more people in physics theory than experiment. Which provides an explanation to the situation. So yeah. All is fine. Jan 11 at 16:09
• @tobalt Ignorance? I teach experimental physics in university. I know how much there is to cover and I also know that there is simply a lot more theoretical/conceptual material. There are fewer courses in any program that teach experimental concepts than theoretical ones. In my experience, a good experimental physics program will have maybe 3 or 4 courses dedicated to that, but 3 or 4 times that many on the theory side of things. There's simply a lot more theory to cover
– Jim
Jan 11 at 16:26
• The reason there are more people working in experimental physics is twofold: First, it sometimes takes more than one researcher to run an experiment, but more than one person to think of a theory is never necessary (though often helpful). Second, any theoretician that says "hey I've got this new theory making predictions. Shouldn't be too hard to test them. Actually, I can do that myself pretty easily. I think I'll do that." is now automatically an experimentalist. To borrow from biology, if a physicist is heterozygous for the research type gene, experimentalist is dominant.
– Jim
Jan 11 at 16:31
• @Jim I was only judging the tone of your comment, e.g. but experimental practices and techniques aren't as varied as the independent topics within the theory side. Well then what about theories which are investigated using several independent techniques? But, yeah you are absolutely correct that in university most real questions are about theory or theoretical exercises. Even the courses on experimental physics, rarely employ a lot of own problem solving but instead stick to techniques given by the supervisors. So its natural that students ask on theory here. Jan 11 at 16:31
• @Jim - most experimental techniques I learned and used in my research were not taught in classes, so using number of classes seems an odd comparison. On the other hand, those doing leading edge experiments often have a network of experts to ask questions of rather than the internet. Jan 11 at 16:45
• @tobalt what I meant from that we use common methods and practices across all of physics. It's not like there's more ways of testing each field of physics than there are topics within that field. That would be chaos. For researchers from one field to have any faith in the experimental results of another, there need to be common elements/similarities that are foundational. For each bit of theoretical knowledge, we shouldn't need to know 3 or 4 bits of experimental knowledge. So I think some unequal weighting is justified
– Jim
Jan 11 at 16:45
• But the most compelling reason is this: One doesn't wake up one morning with no knowledge whatsoever of the theory on which an experiment is based and decide to ask a question about the experiment. I mean, how do they even know about the experiment in the first place? First you learn something of the concept, then you get curious about its experiments. That's a bottleneck for us. It means for us to get a question about an experiment we first have to get a question about the related theory. Not everyone asking about theory is going to be further interested about the experiments. Thus, unequal.
– Jim
Jan 11 at 16:50

There are two questions here:

I am wondering is there a separate SE aimed at experimental physics

No, and in my opinion there shouldn't be. The most important asset of this website is the set of users, because they create the content. As a user and an experimental physicist, I want all of the users looking at my questions. In my daily work as an experimental physicist, I benefit enormously by intimate collaboration with theorists. They notice important features in data, suggest good experiments, explain observed data, and provide useful calculations related to our experiments. Splitting the users seems unwise, in my opinion.

how come there is so little experimental physics being asked here?

I think there are two reasons. First, there certainly was a bias against experiment questions here, and there's some recorded history on that issue. Once upon a time in 2014, I asked a question about lab equipment which attracted a number of close votes; certain users (who I surmise do not understand the nature of experimental physics), voted to close as "off-topic". The discussion arising from that (and other) incident lead to this meta post and its accepted and most-upvoted answer, which in my opinion suggests that questions of the type that I asked should be welcome here.

Now, has anything changed, i.e. are we better about allowing experimental physics questions to live here? My impression is that yes, things have changed. However, perhaps someone could run queries with the various experimental physics tags to see if we've actually gotten better.

Of course, I've only discussed whether or not the situation surrounding questions has improved. A functional Q&A site also needs answers. I can't say whether or not that situation has changed.

Second, I think the most important factor is that experimental physics is less well represented in written material than is theory across all forms of written information. In other words, if there's less experiment than theory on this site, it's probably because there's less experiment than theory at all in any written format. When you were a student, were you ever assigned to read a book on experimental physics [1]? In the highest impact physics magazines (Nature and Science) what's the representation of works focused on experiment? Experimental results are well received, but the techniques and engineering (the kinds of stuff I'd expect to be well served by Q&A) are not. Throughout my career, referee feedback on papers has pushed details on the experiment itself into the "supplementary information" section of the paper (which is not even peer reviewed!) [2]. When I review papers, I regularly have to push authors to include relevant details of the experiment into the main text, even when those details are critical to the message of the paper. I speculate, therefore, that the relatively low fraction of experiment-oriented material on this site correlates with the relatively low fraction of experiment-oriented material in physics literature at large.

P.S. I wrote this answer attempting to address the actual questions in the main post, and I wonder if those are the questions the author really wanted to address. An obvious related question could be "how can we improve this site's accessibility where experimental physics is concerned?"

[1] I wasn't. In fact my physics degree didn't even require basic electronics or even computer programming. It was very focused on theory.

[2] See for example the enormous supplement of the paper on quantum supremacy.

• Thanks for this assessment. "how can we improve this site's accessibility where experimental physics is concerned?" I didn't ask this question initially as I didn't know if that was even on-topic. But as is probably clear from my comments above, I would enjoy a larger focus on experimental physics. Dec 27, 2021 at 18:49
• More and more stuff is pushed to supp. material because 1. people are more and more interesting in the headline result and less and less interested in the details of this result, 2. PRL has a word count that applies to main text, not supp. material. Dec 28, 2021 at 17:53
• "In the highest impact physics magazines (Nature and Science) what's the representation of works focused on experiment?" This is either wrong or a red herring. Theoretical techniques are essentially barred from those venues (same as, or more, than experimental advances). But (from my experience) purely-theoretical papers without experimental implementations are few and far between there. Jan 4 at 18:13
• @EmilioPisanty regrettably true (with exceptions like the KLM paper), yet people still use that metric indiscriminately. You need to start collaborating with experimentalists ;) Jan 6 at 4:51
• @EmilioPisanty ooof yeah I should have clarified that. I meant experimental technique, not all papers with experimental data. Note also that even in papers with experimental data, there is a strong bias against discussing how the data was actually collected. Usually methods occupy one paragraph or are entirely relegated to the supplementary information. Jan 6 at 19:02
• When you were a student, were you ever assigned to read a book on experimental physics [1]? My students are all asked to read and summarize a textbook of their choice on methods in experimental physics. I mean, we also don't teach them electronics or computer programming (oof!), but at least we have that one solitary base covered.
– Jim
Jan 11 at 15:33

I also want to add my own summary of this discussion.

I think the bias towards physics theory questions can be indeed explained by the number of people concerned with physics theory. In my question, I only took professional physicists into consideration (such as employed an institutes and universities), of which a large share work in experimental physics. At least, from a point of view of solid state physics, where experiments can be relatively mundane and can be conceived, built and run by single persons (as opposed to high energy physics or cosmology).

However, when including all the school students, and even most undergraduate students, the situation changes. Most of them do no experimental physics, at least not in the way that they need to solve their own problems but instead stick to prepared protocols. However, they do have to solve their theory problems.

I believe when counting everyone who visits physics.SE (and not only professional physicists) the numbers indeed strongly tip towards behind theory heavy. So this is a natural explanation for the situation.

• Any teaching methodology where some person is in front of a class writing on a board will strongly favour theory, and in some sense this site is an extension of this delivery mode. It’s not like you can “set up” an experiment and ask people to collect data on PSE. Thus, the best we can reasonably hope for (with rare exceptions) is for “theoretical” questions on experimental aspects of physics. Jan 13 at 2:44

The vast majority of topics in this SE seem to be either school/college course related (i.e. with no relation to experimental practice) or academic topics related to all sorts of theoretical physics.

That's probably to do with what people have problems with that can be addressed practically on a site.

While a lot of people have trouble with theory note that many people self-studying don't ever do experiments (and it's not practical for them to try). Many people who do experiments as part of a course have hands-on help explaining the concepts in class before and during.

That leaves people doing their own research. Well that's a problem for the site as they'll typically have implementation specific issues that are not of use to a general audience. That kind of thing is probably better handled by networking with other researchers.

From my personal experience at many universities and research centers, the staff working in experimental physics departments greatly outnumbers those in theoretical physics, so I would expect much more focus on experimental questions in a general "physics" exchange.

It's not clear at all what you expect questions about experiments to be about or what you expect answers to be like.

On this site we're mainly docused on physics concepts. So a question asking for a concept to be explained makes sense here, but many questions about experiments will involved specific details (essentially engineering) of specific implementations of experiments. That's not really a good fit here as we want questions that are useful to a large audience.

I am wondering is there a separate SE aimed at experimental physics or how come there is so little experimental physics being asked here?

Update:

based on initial discussion here a further interesting and related question is: "how can we improve this site's accessibility where experimental physics is concerned?" (quoting Daniel Sank)

I don't think we should.

The issue here is that in answering questions on a specific implementation we're typically not answering questions on concepts.

As it stands it's perfectly acceptable for people to asking about experiments in terms of concepts (and this happens a lot - e.g. double slit experiment questions crop up frequently).

• I had given many examples in a comment yesterday whose answer is now deleted. Maybe a mod can add these examples to my question . Dec 28, 2021 at 7:41
• @tobalt sorry, I deleted the answer because I thought DanielSank one was a better one. The example you gave were" You could ask about recipes for film growth/synthesis, litho recipes, calibration recipes, error mitigation techniques, which technique/detector to use for what, ideas how to extend measurement sensitivity or parameter ranges etcetc. As Well as basic instrumentation and engineering question."
– glS
Dec 30, 2021 at 8:17

based on initial discussion here a further interesting and related question is: "how can we improve this site's accessibility where experimental physics is concerned?" (quoting Daniel Sank)

There should be penalties for those who participate in closing posts that are obviously not off-topic. I don't participate in reviewing posts very much, but I know there are rewards for doing so -- and therefore I suspect there are rewards for closing questions and users get more points for being trigger happy and over-moderating posts.

• As far as I can tell, mods try to be as hands-off as possible. Since they are volunteers, there isn't much rewarding that could go on in any case. Jan 6 at 23:00
• @JonCuster, badges are rewarded based on how many questions are edited/closed/etc. Also, the points and badges received are very real incentives to moderators. Jan 6 at 23:03
• Don't discount that points and badges are, well, very fake incentives. If you look at the stats for various review queues you will find a variety of mods, but that is more indicative of them being around for a while, and may well have substantial weight predating them becoming moderators. They have enough other things to do. Jan 6 at 23:08
• with due respect: it stretches the imagination to think mods care about badges. there is nothing to suggest they actually do care and they already have pretty much an all-access pass, so why would they care? Jan 7 at 0:01
• @ZeroTheHero, By moderate I mean people who participate in reviews and perform decisions that effectively moderate the board (sorry if this meant singling out a smaller set of individuals). Voting to close posts, for example. Anyone with enough points can do this right? There's no penalty for voting to close or successfully closing threads that shouldn't be closed, right? Jan 7 at 0:09
• you should probably edit to make this clear. Jan 7 at 0:44
• @ZeroTheHero, okay I think I edited it in a way that's more clear. Jan 7 at 1:05
• While I like it, it probably won't happen. reason being that closing trash is an important firewall of SE. If users stop doing it because it could harm them, the site might be prone to being flooded with trash questions. Jan 7 at 5:48
• Instead of suspecting something you could have looked it up (in the help center or meta.SE): There are no reputation awards at all for closing questions. There are badges for completing review tasks, but these badges doesn't care whether you vote to close or to leave open. So while you're right that there are no penalties for voting to close what "shouldn't be closed", there are also no incentives in form of either reputation or badges.
– ACuriousMind Mod
Jan 7 at 8:57
• "obviously not off-topic" Who decides what is "obviously" not off-topic ? How is this going to be any less likely to be abused as a mechanism than anything else ? We want people to vote (up or down) and need people who will do the chore work of voting to close if needed. Hanging a threat of punishment over people for doing what's needed is a terrible idea. Jan 9 at 3:42
• @ZeroTheHero,, there is a big difference between downvoting a question and voting to close a question. Voting to close typically requires a lot less people. And I have seen countless questions closed despite being positively received and having highly upvoted answers. Also, if I look at someones profile, it doesn't appears as though I can see very obviously what their history is for voting to close or open threads. If someone is blatantly spamming to vote-close threads, it does not seem as though there's much in the way of seeing this. Jan 9 at 10:56
• @StephenG, "Who decides what is "obviously" not off-topic ?" more people than the original vote. I believe there is already an appeal system, which is not very good in my opinion. "How is this going to be any less likely to be abused as a mechanism than anything else ?" In my opinion, a bad question being left on the website is not as bad as a good question and good answers being deleted. Other than that there are plenty of penalty systems that could be "abused", I see no reason why this is different. Jan 9 at 11:01
• not as bad as a good question and good answers being deleted Closed questions are not deleted and their answers remain (and can even be found by searching). Deletions are rare and most deletions seem to be by the OP rather than member or moderator action. Heavily down voted questions and answers can "disappear" from visibility for low reputation users, but that's seem as a useful thing as in general it prevents bad Qs or As confusing new members with misinformation. No system is perfect, but in general SE works well IMO. Jan 9 at 14:22
• @StevenSagona you are right there is a big difference and I should have written "vote to close" instead of downvoting. I will remove my comment as I can't edit it correctly and it doesn't reflect what I meant to say. 'twas good of you to ping me on the reply. My point is: there's bandwagonning both ways, in the positive and negative direction, but I do think it evens out, and I do think the feedback loop does work in general when a question is improperly closed. There are definitely some well-received questions that should be closed for a variety of reasons. Jan 9 at 16:48