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Theorists, experimentalists and the bias in popular physics

The views expressed are those of the author and are not necessarily those of Scientific American.


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Most people have heard of Paul Dirac but few know about Carl Anderson who, by observing particle tracks in a cloud chamber, discovered the positron (Image: Annenberg Learner)

Most people with more than a passing interest in physics will tell you who came up with the idea of quarks – Murray Gell-Mann.

Now gather around the same crowd which knows about Gell-Mann and ask them who Henry Kendall, Jerome Friedman and Richard Taylor are. It’s very likely that you will draw mostly blank stares.

Yet “coming up with the idea” was as far as Gell-Mann went in 1964 when he and George Zweig independently developed the concept. Without the 1968 experiments of Kendall, Friedman and Taylor at the Stanford Linear Accelerator Center (SLAC), quarks would have remained a mere theory, a will-o-wisp whose existence was confidently postulated but never proven.

Similar themes proliferate throughout the popular view of physics. Everyone knows Paul Dirac who conjectured the existence of the positron, but how many know Carl Anderson and his collaborator Seth Neddermeyer who actually found it? People similarly know about Wolfgang Pauli and Enrico Fermi stating the requirement for a ghostly particle called the neutrino in the 30s, but ask popular science enthusiasts if they are aware of the dogged pursuit of the neutrino by Raymond Davis for over 30 years and you will likely see knitted brows. Finally, even today, a schoolchild would likely know Einstein’s prediction of the bending of starlight by the gravitational field of a star, but Arthur Eddington’s verification of this fact would be little known.

I started mulling over this vivid gap between the public’s appreciation of theorists vs experimentalists on reading a post by physics professor Chad Orzel who, taking a cue from my post about famous American physicists, makes the cogent point that while American theorists lagged behind their European counterparts until the post-war years, they were almost equal to the Europeans even in the 1920s. His point is that we often tend to overemphasize the role of theory over experiment.

Now there’s no doubt that physicists themselves would be the first ones to recognize the value of experimentalists; for instance Anderson, Davis and the Kendall-Friedman-Taylor trio were all recognized by Nobel Prizes. But their recognition in the public mind ranges from vague to non-existent. This gap in perception is especially startling given the singular importance of experiment in physics and all of science, a central paradigm that has been the centerpiece of the scientific method since Galileo (apocryphally) dropped iron balls from the leaning tower of Pisa. Richard Feynman paid a sparkling tribute to the supremacy of experiment when he said:

“In general we look for a new law by the following process. First we guess it. Then we compute the consequences of the guess to see what would be implied if this law that we guessed is right. Then we compare the result of the computation to nature, with experiment or experience, compare it directly with observation, to see if it works. If it disagrees with experiment it is wrong. In that simple statement is the key to science. It does not make any difference how beautiful your guess is. It does not make any difference how smart you are, who made the guess, or what his name is – if it disagrees with experiment it is wrong.”

An even more pointed and roaring tribute to experiment came from the utterly self-assured king of experimental physics, Ernest Rutherford. His opinion of theoreticians was that “they play games with their symbols, but we turn out the real facts of Nature”. And he is said to have admonished the capable students working under his tutelage – nine of whom won Nobel Prizes – to not “let me catch anyone talking about the Universe”.

Rutherford was the ultimate experimentalist and Feynman was the ultimate theorist but Feynman was well aware of how a well-conceived experiment is really the only thing that can make or break a theory. Ironically, the public devaluing of experimentalists applies to Feynman’s own work. The theory of quantum electrodynamics which he developed is perhaps the most accurate theory in physics. As one example, it can calculate the magnetic moment of the electron correctly to an unprecedented 15 decimal places. But we would never have known this if it weren’t for the experimentalists who devised increasingly ingenious experiments to measure the parameter. Yet everyone has heard of Feynman, but who has heard of Lamb, Kusch or Foley?

It seems to me that there are at least two important reasons why the public, in spite of tacitly appreciating the all-important role of experiment in physics, fails to give experimentalists their due. First is the sheer success of theoretical physics in uncovering the deepest mysteries of the universe through armchair speculation. Nobody can fail to gasp in awe at an Einstein or Bohr who, working with a few facts and pencil and paper, divine grand operating principles for the cosmos in short order.

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. Yet this mundane work is an essential step toward the grand finale of hard factual discovery. Even the rare combination of theorist and experimentalist appreciates this; for instance, in spite of his pioneering contributions to theory, Fermi always said that his first love was experiment and he could often be found performing the most mundane of tasks.

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. Anderson might have discovered the positron, but Dirac invented it first. Eddington might have observed deflected starlight, but Einstein simply plucked it out of thin air based on what seemed like magical speculation.

Firstly however, it’s very important to realize that all the awe for Einstein which we rightly feel comes only after the fact, after a thousand increasingly demanding tests of general relativity have established the veracity of the theory beyond any doubt. As Feynman said, no matter how pretty the theory looks and no matter how brilliant its creator sounds, it is no more than a hypothesis until it’s verified. Einstein unverified would have been a mystic. Fortunately the public seems to have gradually woken up to the straitjacket that ugly, grease-and-solder experiment imposes on elegant theory. This is most apparent in the decline of popular versions of string theory; after a period of breathless ascendancy by its proponents, the public seems to increasingly realize the gaping chasm between theory and experiment which the string theoretical framework constantly displays. String theory in fact is the perfect test of the ability of an informed public to distinguish between fact and speculation, and so far the signs seem promising.

Secondly, there are also outstanding example of discoveries made by experimenters which really had no theoretical precedent. That is what makes Rutherford and Faraday the two greatest experimental physicists in history. Rutherford discovered the atomic nucleus in 1908, but it took thirty years for physicists to develop a concrete theory of the nucleus. Similarly Faraday discovered the seamless relationship between electricity and magnetism – one of the very few examples of unification by experiment – but it took until after his death for Maxwell to come up with his pioneering theory of electromagnetism. Experimentalists  often follow in the steps of theorists, but the instances in which they lead the way are as full of creativity and achievement as the work of an Einstein, Bohr or Feynman. And even when they follow, they are the ones who bridge the gap between idea and hard fact.

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; Anil Ananthaswamy is one of those rare writers who has shined a light on the heroic efforts of experimenters in validating cutting-edge theories. In a previous post I mentioned how the public has been fed increasingly exotic and speculative physics fare that tends to influence their opinion about what they consider are the most important fields in physics. Cosmology and quantum theory rank high on their list, condensed matter physics and biophysics rank low. But condensed matter theory still ranks higher than condensed matter experiment. Observational cosmology still takes a backseat to speculations about the Big Bang. This has to change.

If we want to improve the public visibility of experimentalists and place experimentalists in their rightful place in the pantheon of popular physics, the main initiative would have to come from experimentalists themselves. 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? Three years ago the physics Nobel again went to experimenters who used the simplest and most ingenious methods to create graphene. Still there are no vividly written books about these experiments. There are plenty of other motifs, from the observation of supernovae and x-ray astronomy to the manipulation of single DNA molecules using lasers, which can be productively captured in popular physics books. In addition the manipulation of these tools to plumb the depths of nature’s secrets is every bit as exciting to its practitioners as calculating the curvature of spacetime is to its own. It’s up to those who deftly wield this machinery to convey their personal pleasure of finding things out to the public.

Experiment is the ultimate arbiter of science and it’s a pity that the current popular physics literature does not reflect this all-important fact. Experimenters and their journalist friends need to now pick up the baton and run with it. They need to communicate to the public why ion traps are as engrossing as Lie groups, why even the most elegant mathematical edifice can crumble in the face of confounding experimental evidence, why, in Rutherford’s words, “the theorists play games with their symbols while they are the ones who turn out the real facts of nature”.

Update: Tom Swanson, Chad Orzel and ZapperZ all offer excellent perspectives of their own. I concur with their two main observations (Hat tip: Jennifer Ouellette); that experimenters always have to know at least some theory to make sense of their experiments (and Rutherford certainly did), and that temporal and spatial constraints may make it harder for experimentalists to make regular forays into popular science writing. Also, Brian Cox is an experimentalist, not a theorist.

Ashutosh Jogalekar About the Author: Ashutosh (Ash) Jogalekar is a chemist interested in the history and philosophy of science. He considers science to be a seamless and all-encompassing part of the human experience. Follow on Twitter @curiouswavefn.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. ChrisMartin76 9:30 am 06/3/2013

    As Bertrand Russell said, “Work is of two kinds: first, altering the position of matter at or near the earth’s surface relatively to other such matter; second, telling other people to do so. The first kind is unpleasant and ill paid; the second is pleasant and highly paid. The second kind is capable of indefinite extension: there are not only those who give orders, but those who give advice as to what orders should be given.”

    Sadly, this holds true even in academia, even though it takes a lot of intelligence to do the physical lifting in academic fields. Fortunately, there are some fields like psychology, where you have to establish yourself through empirical work before you venture into theory.

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  2. 2. One Observer 11:00 am 06/3/2013

    Contribution is the result of collective effort. Forgive me, but birth did not blind me so. ABC/123 was most certainly passed down to me.

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  3. 3. curiouswavefunction 11:06 am 06/3/2013

    Good point Chris. Biology is another example of a field where experimentalists had to do most of the heavy lifting before any semblance of theory could be brought to bear on the field’s principal problems. Physics is rather special in so far as it relies to an unusual extent on theory. Economics does not, although economists sometimes fool themselves into thinking that it does. Interestingly though, evolution is much more of an abstract theoretical framework than people realize. More on this in another post.

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  4. 4. ts_meyer 11:50 am 06/3/2013

    We’ve been in the midst of a running experiment here, in the US, for the last 33 years. It’s called “Trickle Down Economics.” I wish economist had the same respect for empirical evidence as scientist do. The experiment has been a dismal failure for the economy and people and yet politicians are still selling it to us…. If we had this much negative data for string theory the theorist would have slunk back to their drawing boards years ago.

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  5. 5. Francis Higgins 12:20 pm 06/3/2013

    An excellent article. However, may I sound a cautionary note. There has been instances where devised experiments have failed to prove theoretical assumptions and this has been taken as proof that the theory is incorrect.
    May I suggest that the following are two such cases, not that the results were incorrect, but the results were not fully understood.
    Firstly, the Michelson Morley experiment to test for Aether drag. Looking at the result it is clear that the Cosmos does not contain a stationary Aether, or even an Aether locked to the ‘centre of Gravity’ of the Universe. However, it illustrates that adjacent Matter/Mass generates that which carries the Electromagnetic Wave. Expanding this statement would occupy far too much comment space.
    Secondly, the twin slit experiment re the wave-like nature of the Electron has been misrepresented and misinterpreted by even the great Feynman. That the interference pattern is generated by each individual Electron acting upon itself and not by Electrons interfering with other Electron’s wave functions. Again, too much work and space to explain this conundrum.
    Lastly, the statement that Gravity causes light to bend around great mass, whilst being technically correct, avoids Einstein’s hypothesis that bending of Space Time is the basis of Gravity. I would like to point out that the Refraction of Light is evidence of this, not some Airy Fairy flower-power Physics. That the refraction of Electromagnetic radiation also occurs when a wave passes over from a Land Mass to the Sea and vice-versa. This Refraction being explained by considering that the wave front is subject to a velocity gradient. Alternatively, that Time Dilation, caused by adjacent Mass/Matter, causes that portion of the wave nearer to Mass to travel slower that that portion further away. Same effect, just an alternative visualisation.
    On a lighter note, this means that your feet are younger that your head. It not being possible to measure the ‘flow’ of Time at the ceiling of a room as being different to that at the floor, using the same timing device, due to the Time Dilation caused by the Earth’s Mass. Any Clock/timing device subject to the rate at which Time flows by Time Dilation when moving from one Inertial Frame to another.

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  6. 6. Scienceisnotagenda 12:45 pm 06/3/2013

    Interesting article. Very applicable to my field, geology. Micro and macro practical research’point’ the way specific fields. Theory applies umbrella explanations..leading to more experimentation (research). Sometimes things get off on a tangent but that’s the nature of science.

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  7. 7. Jacques Cousteau 2:30 pm 06/3/2013

    ts_meyer said:

    > If we had this much negative data for string theory

    We do. Or rather, we have no data so far, just a lot of “beautiful equations” written by “smart people.” Imagine if Relativity had gone to the 1960s and still not one aspect of it had been proven…Would anyone still believe in it?

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  8. 8. M Tucker 5:40 pm 06/3/2013

    I really think that some important scientific information IS out in the world for the average person to gather up if they are willing to invest in a little bit of hunting. I also think that some physicists ought to invest in attempting to popularize their particular interests in science. I don’t see any easy fix but I have been able to fill in quite a bit of my own gapping holes in science and science history by relentlessly pursuing some of my favorite topics. One way is for science writers and bloggers to push books that might not have yet become “mainstream” and are not written by those popular authors who show up frequently in the mainstream media.

    I personally think it is very interesting, informative and highly entertaining to learn how we have arrived at our present understanding. One of my favorite experimenters is the little known but hugely influential Henry Moseley. Rutherford and Bohr owe a huge gratitude to Moseley. If Moseley had been as lucky as Eddington had been in escaping the draft and avoiding service in World War I Moseley might be even better known. Moseley’s fait is another reason we should memorialize Gallipoli. History is a marvelously entertaining and informative pursuit.

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  9. 9. mihrant 5:44 pm 06/3/2013

    I liked the article very much and it sheds light the undeniable favorable bias that theoreticians have over experimentalists. I worked on microwave tube research for 25 years and I considered myself neither a theoretician nor an experimentalist, but rather a liaison man between the two. I had a BASIC understanding and appreciation of both the theoretical work as well as the experimental, but I did not have a WORKING ability to do either exclusively. I often had to take abuse from both sides, but more often than not I was in a position to spot discrepancies as well as commonalities in their findings, thus was able to consolidate valid theory with capable experiment.

    The reason the theoretician has the edge with the public is that he deals with equations, which basically are mathematical descriptions of logical statements expressible in WORDs. Thus his pathway to truth ultimately is LOGIC, or WORDs. The public understands and appreciates these. On the other hand, to get at the truth, experimentalists have to devise and integrate “techniques” and “procedures”, not “words”. The public is not at all familiar with these specialized disciplines of experimentation, hence by default, experimental activities are not considered as valuable by the public as the words used by the theoreticians.

    Of course, in practice the fastest course to learning is to use both theory and experiment, and to consolidate them as you proceed, as science has done so successfully. But yes, the experimentalist is more often under-appreciated. As a compensation, however, I think experimentalists get more gratification from their work than theorists, because they ultimately “get ‘er done”.

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  10. 10. rloldershaw 5:57 pm 06/3/2013

    Considering the following list of celebrity conference speakers:
    L. Randall,
    N. Arkani-Hamed,
    E. Witten,
    L. Susskind,
    S. Carroll,

    has any of these people EVER come up with an (1) original idea about nature that has (2) generated a definitive prediction, which (3) was verified experimentally?

    I think you will find that the answer is a resounding “No!”

    They have generated a lot of speculative pseudo-science (extra-dimensions, multiverse rubbish, supersymmetry hype, anthropic pretzel logic, etc., etc., but not one verified discovery about nature.

    What does this say about the state of theoretical physics today? What does this say about the credulous sycophants who hang on their every fatuous pronouncement? What does this say about the science journalism that enables this hype?

    And finally, where have you gone Albert Einstein? Science turns its lonely and very disappointed eyes to you.

    Robert L. Oldershaw
    http://www3.amherst.edu/~rloldershaw
    Discrete Scale Relativity/Fractal Cosmology

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  11. 11. Chryses 5:45 am 06/4/2013

    Ash,

    Thank you for the enjoyable exposition on this facet of Science. I look forward to your next one.

    Link to this
  12. 12. M Tucker 2:11 pm 06/4/2013

    For a look at the experimenters (and the theorists too) involved with the discovery of the particles that make up matter I would like to recommend “Collider: The Search for the World’s Smallest Particles” by Paul Halpern. The book was published in 2009 so it ends with the beginning of the LHC but it does a terrific job of talking about the experimenters and discoverers. He doesn’t just begin with Thompson and the electron he begins with Boyle and Newton and Mendeleev. He mentions all the important discoverers of the components of the atom. Anderson is there along with the Bevatron and Segre. Symmetry, symmetry breaking and supersymmetry are covered. This book has it all except the final discovery of the “Higgs like particle” recently discovered. If bloggers push the book it might become more popular.

    However, don’t expect PBS to do a series based on this book. Do not expect Paul Halpern to present a Broadway show on this subject. Do not expect an article in SA on this. This is science history and the new supposedly cutting edge theory and the new discoveries will always be what is reported in periodicals.

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  13. 13. curiouswavefunction 9:46 pm 06/4/2013

    Thanks all for your comments, all good points. Economics is an example of a field which has tried to piggyback on physics’s success in trying to turn itself into a highly mathematical discipline. In this regard it has enjoyed limited success but much more angst. Turns out humans are a little more complicated than particles to be buttonholed into the intricacies of a Bessel function.

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  14. 14. Dr. Strangelove 2:44 am 06/6/2013

    Joke at CERN: A theoretical physicist was explaining to an experimental physicist a graph showing the result of his experiment, why it has to be that way. The experimenter noticed the graph was upside down. He rotated it to show the correct graph. The theorist went on to explain why it has to be that way.

    In fairness to theorists, somebody said without explanation (theory) science is just stamp collecting.

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  15. 15. nyJan 11:28 am 07/29/2013

    Coming soon: Neutrino Hunters: The Thrilling Chase for a Ghostly Particle to Unlock the Secrets of the Universe (http://www.amazon.com/Neutrino-Hunters-Thrilling-Particle-Universe/dp/0374220638).

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  16. 16. F-exciton 12:01 pm 10/29/2013

    Feynman is the greatest theorist?…I don’t think so. The accomplishments of Heisenberg, Planck, Fermi and others have had a much more profound impact on physics than Feynman (I am in no way saying Feynman was not important…but comparing him to the scientists of the first half of the century…he falls a bit short). While it is true that theorists tend to get much of the credit for large discoveries (which aren’t that often), a quick glance at peer-reviewed physics papers will reveal that during a theory/experiment collaboration, the experimentalist almost always claims first authorship; I’ve worked harder than experimentalists on some papers but still they claim first author (and it wasn’t their original idea). This is not to mention that experimentalists get paid more and have easier times getting grants. Yes, the discoveries of Faraday and Rutherford were great but, ironically, applications of their findings depended on the theory that explained the experiments. One more thing, you say experimentalists “bridge idea and hard fact” — you should know that there is no such thing as absolute fact in science. Just because a few experiments do not confirm a theory does not mean the theory is incorrect (look into a history of science book); my point being that a “fact” can be discredited later.

    If you are looking for fame, you shouldn’t be going into science. Period.

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  17. 17. Experimentalist 8:03 pm 04/29/2014

    I think the premise of this article is slightly off base. The author seems to believe that physical law begins with postulate and ends with observation. It’s not that simple; in fact, it’s more of a chicken-and-egg thing.

    As an aside, the greatest physicist of all time is generally agreed to be Newton, with Einstein second. I would personally classify Feynman as the greatest physicist of the second half of the 20th century — there was a crowded field in the first half. I do believe that Feynman was the greatest communicator in history on the subject of physics.

    Getting back to Newton, he didn’t postulate his laws of motion without prior observation of the relevant physical phenomena. The ancient Greeks failed to “get it,” in part because they tried to invent theories without making measurements. The Newton’s law of gravity was empirically inspired. The most important experiment that led to the theory of relativity is generally recognized to be the Michelson Morley experiment, which showed that there was no “stationary” ether that served as the medium for propagation of electromagnetic waves. Maxwell’s equations were also founded on empirical evidence, and their compatibility with Einstein’s relativity was the first evidence that he got it right. The Bohr theory of the atom wasn’t just conjured up; it was an ingenious fit to pre-existing experimental data, specifically atomic spectra.

    Like the chickens and their eggs, theoreticians and experimentalists work in a cycle. In many cases, experimentalists are trying to validate theories, but in many other cases, theorists are searching for a law that will match known experimental results as well as predict the results of new experiments.

    Feynman has made the point that experimentalists are also theorists in that they apply theories and postulate new ones as well. (See the Feynman Lectures on Physics, for example.) The fact is, however, that few experimentalists have come up with ground-breaking theory. An important exception is Enrico Fermi.

    The reason new theories are formed is typically that we have observations that are not predictable with existing theory, though there are exceptions. As theories have evolved, there are often missing links in the theories that, when addressed, predict the existence of observable phenomena as the author points out. These things tend to get a lot of press, probably in part because they make us feel God-like. Even the development of mathematics has been mostly based on need, although Fourier analysis is an exception.

    When I was a practicing physicist, I would make new observations in the laboratory and try to explain them myself. Then I would seek out both experimentalists and theorists to get their thoughts. Was there an existing theory that would explain what I saw? Even though I classify myself as an experimentalist, I have to admit that the theorists were typically the best at explaining an observation that fell well off of the beaten path.

    If I had it to do over, would I pursue the theoretical or experimental side? Today it’s a tough call. Experiment can be really exciting: you’re actually seeing it and touching it; it happens before your eyes; you feel that you’re standing on the threshold. But experimental physics now tends to require extremely expensive and complex facilities. The “low hanging fruit” has been long-since picked. We can’t look at the stars, or drop rocks from buildings, or piece together apparatus in a garage and discover a new law of physics. Theoreticians, on the other hand, need a pencil and a computer and they’re good to go.

    And, BTW, like most people, I’m more impressed by the great theoretical physicists than by the great experimentalists. It’s just that experiment can be a lot of fun.

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