What scientist is most in need of a good popular biography?

By “popular biography,” I mean things like Norton’s Great Discoveries books, several of which Ive reviewed here, including Krauss on Feynman and Reeves on Rutherford, two books that I keep coming back to for useful tidbits. These aren’t deep works of historical scholarship, and don’t necessarily attempt to be definitive, but focus on being accessible and readable.

There are only a small number of these out there, though, and many important scientists don’t have this kind of bio yet. So, the question to be answered in comments is: who should get one of these sorts of books that doesn’t already have one?

I’ve been reading a lot of history of physics recently for the book-in-progress, specifically about the history of QED, and I think at this point, I’d probably vote for a Wolfgang Pauli biography. This may seem odd, as Pauli was a theorist’s theorist, who was so inept in the laboratory that some experimentalists once attributed a lab failure to the fact that Pauli was changing trains in their city at the time that their apparatus broke.

At the same time, though, the histories I’ve been reading put Pauli at or near the center of physics in the mid 20th Century– he contributed to all the major problems, and more importantly seems to have been a key communications nexus. Everybody working on quantum physics appears to have written to and gotten responses from Pauli. And he was pretty entertaining, in a witheringly sarcastic, quirky sort of way. The photo at the top, taken from Roy Glauber’s autobiography at the Nobel Prize website is a pretty good indication: Pauli was kicking a soccer ball around, and when he saw Glauber about to take a photo of this, he turned and kicked the ball directly into the camera…

So, I bet it’d be fun to read a good popular bio of Pauli. Somebody should get on writing one of those.

Who’s your favorite scientist who ought to get a good popular biography?

As I told my thesis student, I’m not always the best about praise and positive reinforcement– I tend to react to progress in the lab with “That’s great. Now, the next thing to do is..” But this year’s class was a good bunch of students, and it’s been a pleasure to work with them over the last four years.

So, congratulations to (from left to right in the photo above) Mark, Christine, Pavel, Adam, Colin, and Halley. It’s been fun having you around, and best wishes for success in your future careers.

The reason for all this driving around was that on Saturday evening, I was inducted into the Whitney Point Central School District Hall of Fame. This is, quite literally, a hall, run ning from the front lobby of the high school to the cafeteria (more or less):

The Whitney Point Central School District Hall of Fame

It’s also very new– this was the third year– but I think it’s a great idea, and I’m deeply honored to have been included. They’ve got three categories– alumni, school employees, and community members– and include people who have made significant contributions to the community or their chosen profession– in my case, science and science communication. The other honorees this year were Dr. Dan Driscoll, who graduated from WP in the 60′s and came back after medical school to start a practice in town; Marv and Alice Gregg who ran the main grocery store in town; Barb Quarella who taught basically every kid in town my age and younger to swim; and Iva Jean Marsh Tennant, who is an alumna from the 60′s and a distinguished math teacher at another school in the area.

Like I said in my thank-you speech, it’s an honor to be included with people who have been such an integral part of the community for so long. The school has meant a huge amount to me and my family– not only did my sister and I and two cousins graduate from there, but both my parents worked in the district (my father taught sixth grade for 30-odd years, my mother was the elementary school librarian for several years before moving to the local BOCES), my aunt and uncle worked in the district (my uncle taught social studies in the high school, my aunt taught in the elementary school), and I still have cousins in town working with the school.

There’s a running joke in my family about my maternal grandmother claiming to have a plaque in her honor in the long since demolished public school she attended in the Bronx. That adds a little extra amusement to the fact that I really do have a plaque in my honor in in the high school I attended (pictured at the top of this post; the citation is very long, so I’m not going to transcribe it, but it will presumably be added to the web page at some point). But mostly, as I said, I’m honored to be included in a community that’s meant so much to me over the years. And if having my picture and bio up there helps another kid from the area to consider a broader range of career possibilities, including even SCIENCE!, then that will be more than worth the additional travel on a busy weekend.

This has nagged at me for a while, though, and last week at DAMOP, I took the opportunity to ask a bunch of people who seemed likely to have opinions on the subject about it. I’m not sure the result is any more conclusive than it would’ve been some months back, but I have some free time right now, so I’ll write it up this time, and see what happens. Again, I’m going to leave the details of responses a little vague, in hopes of not getting anybody other than me in trouble; I’m not a professional journalist, and didn’t solicit quotes as a reporter, so it would feel wrong to directly attribute words to specific individuals in writing it up on the blog. Ultimately, I’m giving my own take on the matter after discussion with a bunch of people who know the specifics better than I do, and this shouldn’t be taken as more than that.

The whole thing starts with a Nature paper from 2010 by Holger Müller, Achim Peters, and Steven Chu (because writing Nature papers is how Steve Chu unwinds) that sadly is not on the arxiv, because Nature. This paper re-interpreted some earlier results that used the interference of atom waves to measure the acceleration of gravity (from 1999 and 2001) as a measurement of the gravitational redshift instead. This was followed not long after by a comment from a French group including Chu’s co-Nobelist Claude Cohen-Tannoudji. This drew a response, then a counter-response, and a back-and-forth argument that got fairly heated for scientific literature, and can be traced in the citation history of the original paper. The Clash of the Nobel Laureates angle to the whole thing gave it a little media juice, and one or two of the papers sound annoyed enough to make me suspect that if either side had access to a kraken, it would’ve been released long ago.

So, what’s going on, here? The experiments at the heart of the whole business use an atom interferometer, shown schematically above in a figure taken from the arxiv version of a Phys. Rev. Letter by Mike Hohensee and the Chu group (RSS readers need to click through). The idea is that you start with a bunch of atoms at the lower left at time zero, split them in half, and launch half of them upward. Some time later, you stop the bunch that was launched, and launch the bunch that was stopped. When the two bunches get to the same position, at the upper right, you mix them together, and look at how many come out on the two possible exit paths. Since quantum mechanics tells us that atoms behave like waves, there will be an interference pattern here that depends on the “phase” of these waves, or more precisely on the difference in phase between the two.

In the absence of gravity, the two paths followed by the atoms should be more or less identical, and correspond to the straight dashed lines in the figure. When you turn gravity on, the atoms move on the curved paths instead, and you find that the phase difference between them depends on the strength of gravity; thus, you can use this to measure the strength of gravity. This was demonstrated by Kasevich and Chu back in 1991 when dinosaurs roamed the Earth and I was a callow undergrad. (Full disclosure: I worked for Kasevich as a post-doc at Yale in 1999-2001.)

That was a nice paper, and everybody was happy with it and the two better measurements in 1999 and 2001. The key to the 2010 paper by Müller et al. is a re-interpretation of the basic scheme. Rather than thinking of the atoms as waves undulating along these paths, they pointed out that you could think of the atoms as little clocks, oscillating at a frequency known as the “Compton frequency.” These clocks, according to relativity, “tick” at different rates depending on their state of motion and their position relative to the Earth. In this picture, the atoms on the upper path “tick” at a different rate than those along the lower path, and the result of this difference is a phase shift that shows up in the interference pattern. Thus, the measurements Peters and company made in 1999 and 2001 can be viewed as a measurement of the “gravitational redshift,” and a test of relativity.

That re-interpretation ruffled a lot of feathers, for reasons that were unclear to me. In the end, the simple calculation of the gravitational redshift ends up depending on exactly the same strength-of-gravity parameter g as the acceleration measurement, so it seems like just a matter of terminology. Somewhat more formally, you can cast the phase difference that you measure in the experiment mathematically as the sum of three terms, one having to do with the interaction between the lasers used to push the atoms around, and the other two having to do with the motion of the atoms. When you work it all out, it turns out that you can make the laser-interaction term exactly equal to one of the other two, and which one you pick determines whether you call it an effect of acceleration on the atoms, or an effect of gravity on the internal “clocks” of the atoms. Either way, the difference is the same, and tells you something about gravity.

My initial take on this was that the negative response was prompted by the fact that it seems kind of cheesey to get a second Nature paper out of re-analyzing ten-year-old experimental data. Had this been an entirely new experiment, I would’ve said “Hey, cool!” but since it was just a new interpretation of old results, it was more “That’s cool, but…” This doesn’t explain the vehemence of the responses, though, or the way it dragged on through a couple of years of dueling papers.

So, what was the result of my asking around? First and foremost, the dominant reaction I got when I brought this up was “Oh, God, not this mess…” Even people who went on to give strong opinions one way or the other started by rolling their eyes at the whole controversy; a few refused to talk about it at all.

Among those who went on to give opinions, the general responses can be broken into two classes: funding, and personalities. The funding argument is basically that the mostly-European groups that have objected to the reanalysis have a vested interest in keeping the interferometer from being seen as a redshift measurement, because there’s a European mission to make gravitational redshift measurements in space, and if you can do just as well on the ground, that puts millions of Euros of grant money at risk. The personality argument is basically that while the interferometry experiments are very clever, the clock/redshift interpretation is overselling them in a way that bothers some people; Cohen-Tannoudji in particular is seen as a very level-headed guy, not prone to overhyping matters, which inclines some people toward his side.

Outside and between these two camps is a third view, which I’ve moved toward after last week’s conversations, which is basically the “shut up and calculate” analogue: that whether you call it a test of redshift or an accelerometer, what you’re really doing is looking for a violation of the Equivalence Principle. The name you give it is just semantics, and what’s important is that a) the Equivalence Principle works, and b) testing it at high precision is Really Cool. The controversy has cooled off significantly, and there may be some movement toward, if not a reconciliation of the two views, than at least something along these lines.

Of course, lots of new stuff could happen. In particular, Müller and company earlier this year doubled down on the clock interpretation of the interferometry experiments with a Science paper on a “Compton Clock” (not on the arxiv, because Science). This is based on the observation that, if you tilt your head and squint, you can write the required laser frequencies for the the interferometer experiment as fractions of the Compton frequency (which is around 10²⁵ Hz, ten billion times higher than the laser frequency, give or take). The Compton frequency depends only on the mass of the atoms, so if you view everything as a fraction of that, stabilizing the lasers based on the interferometer signal amounts to referencing your “clock” directly to the mass of the atoms.

This is only indirectly related to the earlier controversy, though it recapitulates the essential features: it’s a really cool experiment, based on a clever idea that strikes a lot of people as over-selling. Questions about the “Compton clock” got even more eye-rolling than questions about the original controversy, with a lot of people thinking it’s basically too clever for its own good.

For their part, Müller’s folks stick to their guns on this– a person I spoke to from that group insists that there aren’t any other frequency sources involved, and that the “clock” frequency they get is extremely repeatable and comes naturally out of the experiment, suggesting it really is something to do with their atoms. Unfortunately, they’re not really set up to do the test that would be most convincing: their interferometer uses cesium, which has only a single abundant isotope suitable for the experiment. As with so many other experiments in AMO physics, this would be much better if they used rubidium, which has two abundant isotopes, rubidium-85 and rubidium-87. In that case, they could run the “clock” for both, and show that the fraction they measure differs by 2/87ths, an amount that really wouldn’t show up anywhere else.

Of course, the unfortunate reality is that Müller’s lab is only set up to work with cesium, while the obvious lab to do this in rubidium is run by one of the European groups opposed to the whole idea. So I wouldn’t expect a completely dispositive resolution of this any time soon. It will probably remain a source of (low-level) controversy for a good while yet…

And that’s what people were arguing about at DAMOP last week.

I’m not normally the one who initiates this, but I was wondering: When you were at DAMOP last week, did you see any really neat physics? Oh, sure, tons of stuff. It was a little thinner than some past meetings– a lot of the Usual Suspects didn’t make the trip– but there were some really good reports from a lot of groups.

Anything really surprising? Well, there was one talk that I really liked a lot, that I went to on a lark, because I didn’t understand what the session title could possibly mean, and there was no abstract for the talk: Experimental Studies of Ultracold Few-Fermion Systems in the Dynamics of Ultracold Few-Atom Systems session.

That’s certainly unusual. Do you think you could explain why it was so interesting? Sure, let’s do that.

Wait, really? You’re actually going to blog about real physics? In Q&A format? Yeah, sure. The academic term is over, and the alternative is to read people sniping at each other about politics, which is incredibly depressing. And might lead to writing about politics, which would be worse.

Right, then, few-atom physics. Why is that interesting? Aren’t people usually more fired-up about many-body physics? Exactly why I was puzzled by the session title. And since the other three talks all appeared to be theory-heavy, even without an abstract, I thought this was my best bet for finding out. And I’m glad I went, because it was about three really cool papers worth of stuff from the Ultra-Cold Gases group of Selim Jochim at Heidelberg. Jochim was listed as the speaker, but I half remember it being somebody else– I didn’t quite catch the introduction. I’ll talk about two of the three papers worth of stuff.

Why not all three? Because the third doesn’t appear to have been published yet. The other two are on their Publications page; the final journal articles are linked below in the ResearchBlogging code, but I’ll work from the arxiv versions ofDeterministic Preparation of a Tunable Few-Fermion System and Fermionization of two distinguishable fermions, because they’re free and I can borrow figures from them.

Fermionization of fermions? Are they in the Department of Redundancy Department? It sounds odd, I’ll grant, but actually makes sense. First, though, we need to talk about the preparation of the system.

OK, what are they preparing, and how? Well, like the title says, they’re creating systems involving only a few fermions– they can dial in between 1 and 10 with 90-ish percent fidelity. They start with an ultra-cold gas of lithium-6, which has an odd overall number of protons, neutrons, and electrons and thus behaves like a composite fermion, load them into a very tight laser trap, and then dump most of the atoms away, leaving only a small number of them behind. The basic scheme is shown in the “featured image” at the top of this post– RSS readers have to click through. They load a bunch of atoms into the laser trap, represented schematically as a sort of “well” in the pictures at the top of the figure, with the energy of an atom increasing as it moves out from the center. Then they lower one side of the trap by applying a magnetic field, and atoms with higher energies leak out. They set the energy level of the “leak” by the applied field, and after they turn it off, they have a deep trap containing a set number of atoms whose energies are below a certain level.

But, wait, why does this give them a set number of atoms? Shouldn’t they just get a random assortment of whatever atoms happened to have low energies? Ah, but these are fermions, so they know exactly how many atoms there are in the trap: two per energy level.

Ummm… Maybe you could remind me what a fermion is, again? Oh, sorry. A fermion is a particle that has intrinsic “spin” angular momentum of one-half a fundamental unit, like an electron. These have some unusual properties that SteelyKid once helped me explain, which lead to the famous Pauli Exclusion Principle: no two identical fermions can occupy the same energy state.

The lithium atoms in the trap are fermions, and thus subject to the Pauli principle. In the trap, then, the atoms “fill up” the available energy states– there are only certain specific energies allowed in the trap, because of quantum physics– and when they let the higher-energy ones leak away, they know exactly how many they have left over.

OK, but those cartoons clearly show two atoms in each state, a red one and a blue one. Good catch. They have two atoms per state because the Pauli principle forbids identical fermions from occupying the same state. If you put them in two different internal states (represented by the red and blue circles), though, they become “distinguishable” (there’s a small subtlety to this that justifies scare quotes, but isn’t important for the experiment), and you can have one of each energy state. This becomes important later, so keep that in mind.

I’ll try to remember it. So, they set the energy level they want to let escape, and then they know they have two atoms per state below that point? Right. And since their atoms are extremely cold and their trap is extremely tight, they can choose the “leak” point to keep anywhere from one to five energy states, or one to ten atoms, total. They measure this by the amount of light the atoms scatter, which gives them the mean atom number in the figure at the top.

That looks kind of continuous, dude. Yeah, it’s not the greatest figure. If you really want to believe in their ability to pick a set number of atoms, the figure you want is this one from the “Supplementary Information” section:

Figure S1 from the arxiv version of the preparation paper discussed in the text.

This is a histogram, showing the number of times in their experiment that they got an amount of flourescence corresponding to a particular number of atoms. The horizontal scale is set after the fact, once they’ve identified the mapping from light intensity (a continuous variable, binned for convenience) to atom number, and you can clearly see eleven distinct peaks, corresponding to atom numbers from zero to ten.

Why are the even-numbered peaks so much bigger? Oh, wait, it’s the Pauli thingy, right? Exactly. They start out with two atoms per state, and the only way to get an odd number of atoms is to set the leak level to a point just barely above the highest state they want to keep, and have one of the two atoms in that state leak out anyway. It’s much easier for them to dump atoms two at a time, keeping an even number behind.

Okay, so they can pick between one and ten atoms to keep. Why is this interesting? Well, for one thing, it’s just cool to have that level of control. More than that, though, it lets you look at a weird regime of few-body physics. If you have only one atom, that problem is easy to solve, and if you have an effectively infinite number of atoms, there are powerful statistical techniques that can be brought in to get relatively easy answers to anything you’d like to calculate. More than one but less than an infinite number turns out to be really hard, though– two is mostly doable, three is extremely difficult, four is all but impossible, etc.

Since these guys can dial up a small number of atoms very cleanly, though, they can experimentally investigate this regime, and provide clear results to check theories. Or just motivate people to do theory for this sort of situation in the first place.

Yeah? Give me an example. Well, that’s the second paper.

The redundant fermionization thing? Yep, and before I explain that, let me just point out that “Redundant Fermions” would be a great name for a band.

Duly noted. Get on with it. Right, so there’s one additional knob they have to turn on this system, which is the strength of the interaction between the atoms. When they have two distinguishable fermions sitting in the same energy level, they’re effectively right on top of each other, colliding at high rates. Those collisions change the energy of the state in a way that depends on the details of the collision process. The full physics is very complicated, but what you need to know for these purposes is that applying a magnetic field can change the nature of those interactions in a way that allows them to dial in effectively anything they want. They can make the two atoms occupying a single site behave like they’re weakly attracted to each other, or like they repel each other fairly strongly, and anything in between.

That interaction, in turn, determines the exact energy of the two-atom state, and is kind of tricky to calculate. Being able to measure it in a controlled way is a great tool for looking at these systems.

And what do they see? This:

Figure 4 from the arxiv version of the fermionization paper discussed in the text.

This graph shows the “tunneling rate,” which is a measure of how quickly the atoms “leak out” of the lowest energy state in the trap, as a function of the magnetic field. The magnetic field, remember, controls the interactions, which determine the energy of the state, which in turn controls the rate at which the atoms tunnel out. The vertical scale is logarithmic, so the blue points, representing the situation where they only have two atoms in the lowest state of the trap, span a factor of 100 in tunnelin rate.

Okay, that’s a wide range of control. What are the green points, that don’t do anything? The green points are a system that also contains just two atoms, but in different energy states of the trap. The way they do this is by keeping four atoms initially, so each energy state has two atoms in different internal states. Then they selectively throw away atoms in one of the two internal states, leaving only two identical atoms in the trap.

Since these are fermions, and have the same internal state, they can’t both sit in the same level of the trap, so one must have a higher energy than the other. They also aren’t affected by the magnetic field as strongly– the interaction strength that changes with the magnetic field is the interaction between two atoms in different internal states. The interaction between identical atoms is only weakly affected, and thus doesn’t shift the tunneling rate by any significant amount over the same range of field.

So, how does this represent fermionizaton of fermions? Well, the key feature there is that these two graphs cross each other. So, there’s a particualr interaction strength (set by the magnetic field) at which the two “distinguishable” atoms in the same energy state have the exact same tunneling rate as two identical fermions forced to occupy different energy states due to the Pauli exclusion principle. For that value, then, they’ve “fermionized” the particles that ought to be distinguishable, and thus exempt from Pauli exclusion.

That’s kind of cheesey, dude. Yeah, well, it’s not my term. And anyway, the mere fact that they’re able to play around with the interactions and the fundamental character of these states is pretty awesome, whatever you call it.

Yeah, that is highly neat. So, would you care to close this out with a teaser for this third, unpublished paper whose existence you hypothesize based on the talk? Sure. The speaker also presented some data that aren’t in any of these papers, showing the effect of changing interaction strength for systems with different numbers of atoms, from 2 to 10. Again, this is the really complicated range– you can get an exact solution for one atom really easily, and two with a bit of work, and if you have enough atoms to be effectively infinite, you can use statistical mechanics to get an answer with relative ease.

The system they have lets them look at the experimental value for a bunch of different cases; the two-atom cases fits theory very nicely, but does not match the infinite-number solution. Somewhere between two and infinity, though, the real system of a finite number of atoms has to start looking a lot like the ideal system of an infinite number, and they can investigate where that happens.

Which is…? The subject of their next paper, presumably. I hate to give it away, though…

If I promise to do another Q&A about this stuff when it comes out, can you tell us the number? Four. Four-ish, anyway. But we’ll have to wait for the next paper to see exactly.

I look forward to it. Thanks for the explanation– that was pretty cool. Hey, thanks for giving me something to think about besides depressing politics.

Zürn, G., Serwane, F., Lompe, T., Wenz, A., Ries, M., Bohn, J., & Jochim, S. (2012). Fermionization of Two Distinguishable Fermions Physical Review Letters, 108 (7) DOI: 10.1103/PhysRevLett.108.075303

Serwane, F., Zurn, G., Lompe, T., Ottenstein, T., Wenz, A., & Jochim, S. (2011). Deterministic Preparation of a Tunable Few-Fermion System Science, 332 (6027), 336-338 DOI: 10.1126/science.1201351

The bottom line is: People need to decide if they want to be heard, or if they want to be validated. I have long been an associate editor at PLoS ONE, and once I edited a paper that received a lot of critical commentary. That journal has a policy of open comment threads on papers, so I told disgruntled scientists to please write comments. The comments appear right with the article when anybody reads it, they appear immediately without any delay, and they can form a coherent exchange of views with authors of the article and other skeptical readers.

Some of the scientists didn’t want to submit comments, they wanted to have formal letters brought through the editorial review process. “Why?” I wrote, when you could have your comments up immediately and read by anyone who is reading the research in the first place? If you want to make an impact, I wrote, you should put your ideas up there right now.

Having just been at a conference where I talked to a bunch of friends who are pre-tenure, or just received tenure, I have a slightly different spin on this. I don’t think it’s affirmation they need, it’s publications. If you have a tenure-track job, or hope to someday have a tenure-track job, you have to be worried not so much about your impact on journal readers as your impact on job application readers and tenure review committee readers. And whatever additional impact and immediacy comments on an article might have, they are not citeable publications, and as such are a poor investment of resources for a pre-tenure faculty member.

If you’re going to put in the effort to do a proper job of countering a poor paper, it ought to result in at least a formal letter brought through the editorial process, because that’s a line you can add to your CV. “I left a devastating comment on the PLoS ONE page of a stupid article” is not something you can, at present, cite. And even people with tenure are products of a system which only rewards citeable publications, and thus are conditioned to not publish stuff that can’t be cited. The stakes get somewhat lower after tenure, but it’s not until the full professor with an endowed chair level that it stops mattering at all (because there’s no further possibility of promotion), and by that time, it’s been decades.

Now, you can maybe argue that this is a failure of vision on the part of the current culture of academia, and I’d agree with you to a point. Maybe there should be a way to cite and get professional credit for comments left in response to journal articles, and blog posts about journal articles, and the like, but right now, there isn’t. And given the stakes– hundreds of applications for a single tenure-track opening, the slim odds of getting a second chance if you fail a review, I don’t think a lack of eagerness to embrace new media can really be held as indicative of a character flaw. Affirmation in academia doesn’t just mean a warm-fuzzy feeling, it means continued employment.

If you want to get more academics posting to blogs and leaving comments on journals that accept comments, you need to provide a way to cite those and credit those as scholarly publications. Which is going to take time to get accepted, and is going to require some senior people to take the lead.

And, of course, there’s a tricky line that needs to be walked, here, because while giving credit for blogs and comments would encourage more participation, it risks becoming yet another mandatory drain on the finite time and energy of faculty. We need a shift in academic culture to not only credit more things, but be more flexible about counting different distributions of things as equally valuable. Blogging should not be mandatory.

So, this is a more complicated situation than just wanting people to publicly approve of your comments. There are very good reasons for academics to be skittish about blog and journal comments, beaten into our heads over many years, and it’s not going to be a simple matter to change that.

(Ironically, I probably would’ve just left this as a comment on Hawks’s blog post, but there doesn’t seem to be an obvious way to do that…)

To the dismay of many students entering science majors, public speaking is a very significant part of being a professional scientist. Scientists are expected to give talks of a variety of different lengths– 10-15 minute “contributed” talks at big meetings, 25-30 minute “invited” conference talks, 45-60 minute seminars and “job talks.” Oral presentations are one of the most important ways in which we communicate scientific results to other scientists.

And yet, the way scientists do public speaking is… very odd. We place a great deal of importance on public speaking, and most professional scientific talks are meticulously prepared. And then they’re delivered in a way that attempts to make them seem like off-the-cuff presentations.

The factor that made me think the guy giving that DAMOP talk was new at this was that he had very clearly memorized a prepared text. It wasn’t quite a rote recitation– he managed to vary the inflection of his voice in the ways appropriate for normal human speech– but he clearly knew exactly what word came next in each sentence. And while that’s a fairly effective way to deal with giving a talk when you’re not comfortable doing it, it’s extremely unusual in scientific presentations, particularly in physics. I’ve been going to scientific talks for better than twenty years, now, starting with colloquia at Williams when I was an undergrad, and I only hear clearly memorized text a couple of times a year.

What’s much more standard is a talk where the speaker has put a great deal of thought into their slides, and the key ideas that need to be expressed on each, but where they try to make up the exact wording of the talk as they go. Which means that, when you hear talks from scientists with a lot of practice giving talks, you tend to hear “Um” a lot. And also verbal filler like frequent sentences starting with “So, we see that…”

It’s kind of a weird business in that respect. To some extent, of course, this is just what good public speakers do– during the last Presidential election, there was a fascinating comparison of Bill Clinton’s DNC speech in 2012 with the prepared text he had written, and it’s chock full of brilliant ad-libs, and also the occasional bit of folksy verbal filler (“Now, folks…”). But even Clinton was working off a prepared text projected in front of him on a Teleprompter. Which is something basically no professional scientist does.

Instead, we have a very strange relationship with our PowerPoint slides. The slide in the “featured image” at the top of this post is the title slide from one of my research talks, listing my collaborator on the original proposal, and the students and funding agencies who have contributed. A typical slide from the middle of the text looks like this:

A slide from my research talk

That’s a fairly typical sort of slide for a scientific talk–if anything, it’s probably a little lighter on text than most of the slides I saw at DAMOP. The slide has a schematic diagram– in this case, a cartoon version of a proposed astrophysical detector using liquid neon as a scintillation medium. There’s also a list of important points regarding the proposal over on the left side; in the actual presentation, these are minimally animated, so I reveal each as I get to it– you only see the full thing at the end of the spiel, just before I change to the next slide.

The list-of-points thing is a little risky– people can generally read faster than you can talk, which is part of the reason for the minimal animation. Having the text present serves two purposes, though: one is as an aid to anyone who’s taking notes– which really does happen at conferences– but the most important function is as a reminder to the speaker. It’s considered bad form to explicitly speak from notes, as is common in the humanities, and so scientists use prepared slides with text to cue them as to the next key point. Which leads to a lot of “Um” and “Uh” as the speaker does the mental reconstruction of the text.

(There are occasional hints that this is a recent-ish development– if you look at some of the many videos of Feynman lecturing– this one, say– he’s frequently referring to notes, not using slides or an overhead projector. By the time I entered physics in the early 1990′s, though, everything was overheads, and a chalk-talk from notes was very rare. these days, it’s all PowerPoint or the equivalent.)

This is, as I said, a very strange situation when you stop to think about it. Professional scientists spend a great deal of time speaking in public, but we do it in a manner that is designed to maintain the pretense of spontaneity. And because of that, even experienced speakers frequently appear sort of amateurish compared to speakers in politics and business. Students are often specifically coached not to memorize a specific text, just the key points, and to invent the exact words as they go. And people who are clearly working from a carefully crafted script stand out as unusual in the context of a week-long meeting.

Why it is that we do this is one of the enduring social mysteries of science. It’s very deeply ingrained, though– even when I do public lectures, where I very deliberately eliminate almost all the text from the slides, I still don’t go from memorized text, but use the images on the slides to cue myself as to what to say next. The exact words are invented on the spot. Which allows for fewer really clever turns of phrase, and creates a lot of space for verbal filler.

(By the way, if you want to see the full presentation those slides above came from, to verify that the examples are fairly typical, here it is on SlideShare:

(That might not be the exact version I grabbed the screenshots from, but it’s very close.)

The idea of the game is to stick together two song titles that overlap by one word (last word of the first title, first word of the second) so as to make an amusing combination of some sort. The post title is probably my best effort in this direction (also, the first one I thought of), combining The Band and the O Brother, Where Art Thous soundtrack. Here are some others (artists listed in parentheses when I think they’re obscure enough to need it; not all of these are songs that I own, or even like, but I know the titles):

1. I Don’t Wanna Grow Up on Cripple Creek (Tom Waits/ The Band)
2. American Girl from the North Country
3. My My Hey Hey Hey What Can I Do
4. Beautiful Wreck of the Edmund Fitzgerald (Shawn Mullins and Gordon Lightfoot)
5. Bat Out of Hell’s Bells
6. Another Day in Paradise by the Dashboard Light
7. True Love Travels on a Gravel Road to Nowhere
8. The Body of an American Pie
9. Your Little Hoodrat Friend of the Devil
10. Bring on the Night the Lights Went Out in Georgia
11. Runnin’ Down a Dream of the Blue Turtles
12. Walk of Life in a Nutshell (Dire Straits/ Barenaked Ladies)
13. Tonight I’m Gonna Rock You Tonight Is the Night I Fell Asleep at the Wheel (Spinal Tap/ Barenaked Ladies)
14. Midnight Train to Georgia on My Mind
15. Pay Me My Money Down by the Water
16. Sweet Home Alabama Song (Whiskey Bar) (which would actually almost work as a mashup if you put the Brecht chorus with the Skynyrd verses)

And as an indication of how punchy I was getting as I thought about this nonsense during the car ride from Quebec to Niskayuna to Williamstown, two that involve mangling a song title for comedy value: “Bottle of Fur Elise” (Urge Overkill and Beethoven), and “No Woman, No Cry for Me Argentina.” And that last one (including the fact that I find it funny) is probably as good an indicator as you’ll get of my mental state at the moment, so I’ll shut up now. You can almost certainly do better; leave your suggestions in the comments.

(*- I say this for two reasons: First, that it was a solid week spent in an intense environment (well, two of them) surrounded by really smart and interesting people, and second because last night was the first night in a week that I was asleep a) before midnight, and b) without drinking a bunch of beer first.)

Happily, ZapperZ and Tom at Swans On Tea offer more or less the response I would’ve if I’d had time and Internet connectivity. Tom in particular gives a very thorough exploration of some of the reasons why experiment gets downplayed in popular physics. I particularly liked this bit:

I’m going to put forth a possibility: maybe we have a harder job, in terms of popularizing or telling our story (I’m not claiming the science part is easier). What I mean by this ties back to a story from a few years back, when we were saying goodbye to a colleague who had decided to leave to go to grad school in physics. Someone asked him if he was going to do theory or experiment, and the two physicists at the table pointed out that this is a false division: there are people who do theory, and there are people who do both experiment and theory. There is basically no category of physicist who does only experiment. If I am doing an experiment, I have to be aware of what the theory is, and use it, in order to set the experiment up and to properly analyze the data. While I don’t have to create the theory, I am not insulated from it.

That’s absolutely true, and a point that’s seldom brought out. Experimentalists are, for the most part, also required to be mediocre theorists, because you need at least a rough idea of what’s going on in order to design and carry out an experiment. On the other side, though, theorists don’t really need to know the details of the experiment to quite the same degree.

One of my favorite anecdotes from grad school illustrates this point fairly well: in the mid-to-late 1990′s, the effort to produce Bose-Einstein Condensation at NIST in Gaithersburg involved both a theory group and the experimental group that I was associated with (I wasn’t directly involved in the BEC stuff, but it was the Hot Topic of the day, so I followed what they were doing), and for a long time they had weekly meetings of both groups. This ended, however, after an hour-plus meeting during which the experimentalists debated whether to make the coils for a particular electromagnet out of copper tubing with a round cross-section, or copper tubing with a square cross-section. After that, the theorists insisted on splitting off a second, experimentalist-only meeting for those sorts of discussions.

But the interesting point for the current discussion is this: while there was a separate experimental meeting that none of the theorists went to, all of the experimentalists continued to go to what was nominally the “theory” meeting (in another building, across an open field strewn with goose shit, no less). Both groups needed to know the basics of the theoretical developments, but the experimentalists needed a bunch of extra stuff on top of that.

(Now, you could argue that the theoretical analogue of square wire vs. round wire is not what was being discussed at the theory meetings– that would be stuff like details of numerical integration techniques, or whatever, and whether to do the calculation in C or Fortran. I still think it’s true that the experimentalists needed to know more about the theory than the theorists needed to know about the experiment, though.)

There are also some interesting interactions between this discussion and the history-of-science reading I’ve been doing recently for the book-in-progress. The division between theory and experiment wasn’t always quite as sharp as it seems to be these days. Jogalekar cites Faraday and Rutherford as examples of outstanding experimentalists who weren’t good at theory, and it’s certainly true that Faraday didn’t have the mathematical background he needed to fully complete his discoveries. In another sense, though, this sells both men short. Maxwell eventually put Faraday’s ideas on a sound mathematical footing, but Faraday’s intuitive ideas about fields turned out to be dead on (though they were scoffed at at the time). Einstein famously had pictures of only three scientists in his office: Newton, Maxwell, and Faraday, which gives some idea of how he regarded the quality of Faraday’s ideas. And Rutherford, for all his disdain for professional theorists, was no slouch at manipulating symbols, and was adept enough to realize that the experimental results of Marsden and Geiger implied a “solar system” type atom (and also that such a thing was classically untenable).

It’s also been very striking, as I read about the history of the development of quantum electrodynamics (QED), to note how close the connection was between theory and experiment in the first half of the 20th century. In Schweber’s QED and the Men Who Made It, there’s a strong emphasis in the stories of all three of the eventual Nobelists for QED on “getting numbers out.” Tomonaga, Schwinger, and Feynman all came from a physics culture that placed huge emphasis on concrete calculations, and nothing was regarded as complete or well understood unless it agreed quantitatively with experimental results. Some of this was the fact that the problems were simpler and easier to connect to measurements, and some of this might be traceable to WWII, where even theoretical physicists were pressed into service in vast engineering projects. Schwinger is widely viewed as a theorist’s theorist, but he made very practical contributions to the development of radar technology, and Feynman somehow found time between lock-picking and code-breaking to run an extremely successful numerical calculation program at Los Alamos, providing concrete numbers for use in bomb development. And Willis Lamb, one of the people cited as a relatively unknown experimentalist by Jogalekar, was a theorist by training, but got pulled into experimental work by making magnetrons for the wartime development of radar.

(Of course, there were also people like Pauli, who was so inept in the lab that an experimental failure was once attributed to the fact that Pauli had been changing trains in the same city as the lab when the apparatus broke…)

This is getting kind of long, but I want to mention one other aspect. Jogalekar notes that most popularizations seem to come from the theory side:

The other big reason why for the public seems to downplay the key role of experiments is the bias in physics popularization toward theory. And here at least part of the blame must be laid at the feet of experimentalists themselves. For instance if we ponder over who the leading physics popularizers in the last twenty years are, the names that come to our minds include Brian Greene, Lisa Randall, Leonard Susskind, Brian Cox and Sean Carroll. Almost no experimenter makes the list;

I think Tom has this about right:

Another possible reason is that it may be a little easier to fit popularization into your schedule if you can do some of your work while out popularizing. I can’t do an experiment if I’m on a plane, or at a hotel. Theory is somewhat less constrained to being in one particular place. Perhaps that lends itself, in a small way, to this kind of outreach.

I’ll offer one additional point in the same general direction: if you look at the world of physics blogging, you’ll notice that most of the regular bloggers are theorists, and the handful of experimentalists out there tend to come from particle physics or astronomy. Why these fields, given that other specialties are more common in physics as a whole? I would guess that it’s partly due to the fact that in these fields, experimental work is done at a computer. They’re writing code to process images, or sift through terabytes of collision data for events that fit a particular profile. While that’s going on, there’s some slack time that’s easily used for blogging. The smaller scale experiments done in other subfields involve a little more hands-on, in-the-lab time, which reduces the number of experimental bloggers.

I’ll close with one final observation, about fields of research. Jogalekar writes:

There is no doubt that experimental physics has seen some amazing advances in the last two decades, so there’s certainly no dearth of stories to tell. For instance just last year the Nobel Prize in physics went to Serge Haroche and David Weinland who have achieved amazing feats in trapping ions and atoms and verifying some of the most bizarre predictions of quantum mechanics. Yet where are the books which elaborate on these successes?

Well, if you’re reading this on the ScienceBlogs site, you could look over in the right sidebar… If you’re on an RSS reader, here’s a helpful link. And lest this be just unseemly self-promotion, I’ll also put in a plug for Anton Zeilinger’s book (another experimentalist, it should be noted, one of the very best in the world).

It’s true, though, that there’s less popular material out there on experiments in quantum physics. Even popular books that get a good deal of press, like Cox and Forshaw’s are weirdly scanty about modern experimental physics– their book gives almost no indication that quantum physics is still an active area of research, or that anything interesting has been done in the field since the 1960′s. I’m really not sure why that is, and I’d love to see it change. Which is, after all, why I wrote my book the way I did…

Anyway, that’s a lot more than I thought I was going to write when I sat down to start typing. And now I need to run off to the opening session of the DAMOP meeting, to hear about awesome recent developments in experimental physics…

This is a book that can’t really be reviewed just as text, because images are pretty integral to the whole thing. Here’s a screenshot of a fairly representative page:

Spread from Angry Birds, Furious Forces

This is indicative of the format: a page of text, and a big splashy image, often with Angry Birds characters added digitally. The text is very characteristically Rhett– this might be the most blog-like book I’ve ever read, and that’s a good thing. The approach to physics is very much in the Matter and Interactions sort of terms he uses, and the text features lots of little asides in his usual style.

I was a little surprised to find that this covers more than just the physics that’s in the game. In fact, it’s a quick survey of all of physics, from basic mechanics up through the Standard Model. As a result, the connection to the game gets a little strained at points, but then, it would be hard to do a whole book with just mechanics without getting into the math. And while there are occasional equations included as design elements, this is not a mathematical treatment.

So, what’s the target audience for this? Well, the day my review copy arrived, it was lying on my desk when SteelyKid came bopping in. “What’s this?” she asked, noticing the eye-catching cover (reproduced as the “featured image” above”).”

“It’s a book about Angry Birds, and science,” I told her.

“Hey!” she said, “I like science! And I like Angry Birds! I should read this!”

So, to the design folks at National Geographic books: Well done.

I’ve long maintained that Dot Physics is one of the best blogs around, and this carries that basic flavor over into book form. It’s not something that will help you get a 5 on the Physics AP exam, but it should appeal to anyone who enjoys, say, the Basher book on Physics. Plus fans of Angry Birds. And there’s a lot to be said for catching potential science fans young.