Theorists, experimentalists and the bias in popular physics

Ashutosh Jogalekar raises a very interesting point about why theorists tend to be more famous, both in the arena of science and in science communication. I think it’s a valid observation — we do tend to know theorists more than experimentalists; many of the names listed for the experimental followup of theory were unfamiliar to me, and I’m a physicist. I only recognized Eddington, for his confirmation of general relativity.

But there’s more to this discussion. Zapperz notes in his review of the article that while the treatment of when experiment leads discovery is mentioned, it is downplayed. Physics students, at least, would be familiar with some of the names of the physicists who made discoveries, because we discuss the results and sometimes recreate the experiment itself — Stern-Gerlach (spin), Franck-Hertz (quantized atomic states), the Millikan oil-drop (fundamental charge), the Michelson-Morley interferometer (failure to find an aether). But I think it’s true that the general public, or even scientists outside of physics, would not be aware of these names.

Beyond this, there was something that bothered me even more. The notion that the theory is the hard part.

To be fair though, it’s hard not to admire theorists when many experimentalists, as ingenious as their contraptions are, “simply” validate things which the theorists have already said.

Couple that with the aspersions cast on experiment:

Compared to their efforts based on pure thought, the corresponding efforts of experimentalists who get down on their knees, liberally coat their hands with grease and spend most of their time soldering electronic circuits and fashioning precision machine parts on a lathe sounds humdrum and boring.

I don’t know. Diving into equations all day long is what sounds boring, but that’s me. I like working in the lab. And in the lab, we do have those great moments when something special happens. For me, to actually see things happen in the lab is more of a thrill than getting a result on paper. To each his/her own.

But back to this (somewhat disrespectfully phrased, so I will do some chest-thumping) idea that “all” the experimentalists are doing is confirming theory. Experiment isn’t easy, especially when one is doing it at a publication-worthy level! There are a number of skill sets involved, and lots of things can go wrong that have to be tracked down. In my own work I have to understand lasers and optics and do some really PITA alignment of them. I build and/or use electronics to do various jobs like servo-loops and low-noise current sources and amplifiers. I need knowledge of the behavior of electronics from DC to radio-frequency up to microwave. I have to know about vacuum systems and magnetic shields to keep my atoms from being perturbed by effects that will limit the precision of the experiment. And more. All of this in addition to the above soldering and coming up with a drawing for whatever machining has to be done.

And here’s the kicker: often there’s little to nothing in the theory that tells you how to do an experiment to confirm it. There is often a lot of elegance and creativity in a well-designed experiment that gives you the latest and greatest confirmation, that pushes some number out to the next order of magnitude of agreement (or perhaps better still, confirming a disagreement, meaning there’s new physics to be investigated). A lot of clever ways of teasing out more signal amongst all that noise.

Short answer: don’t diss experimentalists. We have lasers, and we know how to use them.

The next question is this,

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?

and I think the answer is also tied into the observation that our most famous physics communicators seem to be theorists:

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’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.

So what’s the impact of this? To explain an atom trap and its usefulness for making a clock (more appropriate for me than the above example referring to ions) I would have to explain the theory, and then describe the experiment. So I have two jobs to do, while the theorist can skip over the details of the experiment and go straight to the result. I can explain the theory of an atomic clock quite generally — electrons can be made to “tick” by jumping between two states, and there are ways of counting how many jumps they’ve made. Since they “tick” very quickly and regularly, we can make precise clocks. (I can, of course go into more detail, depending on the audience). But to explain my particular clock experiment, I have to add in the details about how and why we cool them, why we use the particular atom we do, how we detect the atoms, and how and why we protect them from effects that would disrupt the precise operation of the clock. More things to explain.

Another think to consider is the scope of discussion. Experiment ties you into a particular area. If you trap ions, you are going to do experiments that lend themselves to being investigated by probing trapped ions. Lab equipment is often expensive (in terms of money but also time building up a complex apparatus), so you aren’t going to do one experiment and then start again with something else. Experiments can also take years to set up, troubleshoot and then get data. Perhaps theorists are a little freer to explore other areas and promote them, and work on multiple problems. That diversity might account for some popularity.

Then there’s the speculative nature of theory. If one discusses experiment, one is tied into talking about what we’ve confirmed that agrees with nature. As the article points out, the theorists can get speculative about what the implications of a theory might be, unconstrained by the possibility that the prediction never actually pans out and unfettered by pesky experimental confirmation. While both groups can do some speculation, that kind of freedom — strings, time travel, multiple universes — feeds the imagination, and I think that’s an opportunity for something quite compelling. The danger, of course, is that one might be selling fiction. But perhaps this possible fiction is more engaging than non-fiction.

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 also wonder how much time a theorist spends writing grant proposals as compared to an experimentalist. (Maybe it’s the same, but as experiment generally requires more money, it’s possible the funding pressure and need to write grants is proportionally greater. I don’t know.)

It could also be simply chance. The above list is short, and maybe it’s just a statistical quirk that the big names/rock stars are theoretical folks who also have a talent for communication. But maybe it’s also because the physicist who finally got their experiment running doesn’t want to leave to do this kind of outreach when there’s a chance to take data.

Update: more on this over at Uncertain Principles

NASA’S Swift Reveals New Phenomenon in a Neutron Star

Observations of X-ray pulses from 1E 2259+586 from July 2011 through mid-April 2012 indicated the magnetar’s rotation was gradually slowing from once every seven seconds, or about eight revolutions per minute. On April 28, 2012, data showed the spin rate had decreased abruptly, by 2.2 millionths of a second, and the magnetar was spinning down at a faster rate.

“Astronomers have witnessed hundreds of events, called glitches, associated with sudden increases in the spin of neutron stars, but this sudden spin-down caught us off guard,” said Victoria Kaspi, a professor of physics at McGill University in Montreal. She leads a team that uses Swift to monitor magnetars routinely.

Interesting. I had heard about stars “settling” and that’s fairly easy to imagine: if a star contracts slightly, its moment of inertia gets smaller. Because there is no external torque involved, angular momentum is conserved, and so it must speed up as a result. But a decrease in the spin?

I like that they call this an anti-glitch.

A nice little .gif that shows the concept behind a Fresnel lens