Interna

My household is on the way to Sweden already and I'm sitting in an apartment empty besides the bed and the modem. Yesterday was my last day at PI. Laurent Freidel said the good-bye words at the weekly wine & cheese, and everybody politely clapped their hands, though most of the people present I didn't know. Some of them where students from the recently started PSI program. Laurent did quite a good job, though I always find it weird to hear my CV summarized in a few words. It keeps getting longer. My CV looks so neat, whenever I look at it I wonder where is all the sweat and pain. Can I put them in an additional section?

Since there is no direct flights from Toronto to Stockholm anyway, I will have a few days stopover in Germany which also allows me to pick up some stuff I deposited there earlier. Not to mention that I should say hello to my husband occasionally so he doesn't forget he's married. In Stockholm, am staying the first month in a guest apartment. Experience tells me the first weeks in a new country are very busy, filled with bureaucracy, disorganization and frustration. So expect blogging to be sparse.

Some of you might have followed it on my Twitter account, two weeks ago I had a water damage in my apartment. The water tank in the storage room which preheats the warm water leaked. This must have happened sometime in the evening after I went to bed. I got up the next morning early to make a phone call to Europe and noticed all the carpet was soaking wet. Since I didn't know how to turn off the water and it kept running I had to wake the building manager. He looked at the disaster, turned off the water and reappeared some hours later with a vacuum cleaner sucking out what must have been about 100 liters of water. Later that day a plumber exchanged the water tank. It took a full week for the carpet to dry. Luckily nothing was really damaged, just that I had my moving boxes on the floor at that time. They soaked up the water and basically dissolved. I had to replace several of them and repack which was very annoying.

Though it was clean water, it turned out to leave stains in the carpet. An insurance guy came to assess the damage, later a "carpet expert" came to figure out where the spots came from. He said that there was probably rust in the tank which would have accumulated under the carpet and they'd have to take out the carpet, clean the floor, shampoo the carpet, and dry it. I was hoping they could do that after I've left, but of course it's more important to be nice to the new tenant who'll be moving in Tuesday. So yesterday evening I came home to find an empty living room with a loose carpet and wind machine tucked under it, such that the carpet moves in constant waves. Quite a dynamical inner design. I think it has potential.

The rest of my story in Waterloo will consist of somebody picking up the bed, somebody else picking up the car, my landlord picking up the apartment and house keys, and somebody dropping me off at the airport. You'll hear from me once I'm back in Europe. Meanwhile, a nice weekend to all of you.

Paper Zapping

A nice quote from Strategic Reading, Ontologies, and the Future of Scientific Publishing, by Allen H. Renear and Carole L. Palmer (Science, 14 August 2009, p.829), on how scientists make use of the literature:

Now, as scientists search and browse, they are making queries and selecting information in much tighter iterations and with many different kinds of objectives in mind, almost as if they were playing a fast-paced video game. […] In a compelling analogy, Nicholas et al. describe a "slightly irritated" father watching his young daughter flick from channel to channel while watching television:

[the] father asks … why she cannot make up her mind and she answers that she is not attempting to make up her mind but is watching all the channels … gathering information horizontally, not vertically.

And they conclude

Now we see what the migration from traditional to electronic sources has meant in information seeking terms. We are all bouncers and flickers, and the success of Google is a testament to that, with its marvelous ability to enhance and amplify this flicking and bouncing (like a really good remote) … […]

Just as the aim of channel surfing is not to find a program to watch, the goal of literature surfing, is not to find an article to read, but rather to find, assess, and exploit a range of information by scanning portions of many articles.

A little less conversation, a little more science please

Last time I visited my parents, I was browsing through their magazines and happened to read a particularly upsetting commentary in "Stern," one of the three large weekly German magazines. Since I was sitting in front of my laptop anyway, I wrote a letter to the editor which indeed got published.

Since my letter picked up a theme we've been discussing on this blog many times, the status of modern democracies and the future of politics, I thought I'll post a translation. The article I was replying to is here, (English via Google translate). It is one of the weekly appearing commentaries titled "Zwischenruf," which means roughly an interjection by the audience, written by Hans-Ulrich Jörges. He was addressing the ailing status of our democracies and the increasing frustration of citizens. The cure, he wrote, would be more grassroots democracy.

If you have read some of my posts you know why I couldn't let this uncommented. I've said a great many times that grassroots democracy works well only for a very limited amount of problems. Those in which there are clear and simple questions of large interest for the electorate, and the average person is able to make a qualified decision. Few questions in politics are of that sort, and few people have the time and the interest to deal with the cumbersome details of day to day politics. There are good reasons why we have representative democracies, none of which seems to have occurred to the author of that piece. But what annoyed me much more was that he didn't bother to back up his opinion with any sort of argument or evidence. All together, it was a completely useless ramble that wouldn't even have made a good blog post. If that's the hight of intellectual commentaries German magazines can provide, then poor Germany.

In any case, here's the letter. For whatever reason they dropped the first sentence in the print version.

"Hans-Ulrich Jörges addresses an important issue but draws the wrong conclusions. The decay of democracy and the incapacitation of the people is not a typically German phenomenon, but can be observed in an increasing number of modern democracies. It is a consequence of the inappropriateness of our political systems for increasingly complex tasks. Calling for more grassroots democracy is simple, but not a solution. What we need instead is a scientific, non-ideological, debate about how we can update our political systems to the status of the 21st century. We need less interjected opinions and more scientific studies examining how our political systems can be made more efficient and less frustrating."

What we need, in short, is thus something like the Lightcone Institute :-)

Anonymity in Science

I recently read a very provocative essay in Inside Higher ED

Against Anonymity
By Jeffrey R. Di Leo

To put his point of view into perspective, I think it is useful to know where the author comes from, so here is some info from his website

Jeffrey R. Di Leo is Dean of the School of Arts & Sciences, and Associate Professor of English and Philosophy at the University of Houston-Victoria. He is also president of the Southern Comparative Literature Association.
Professor Di Leo has a dual Ph.D. in Philosophy and Comparative Literature from Indiana University. His teaching and research interests include ethics, contemporary innovative literature, classical American philosophy, aesthetics, philosophy of language, and literary and cultural theory.

Needless to say, I read his essay with the eyes of a physicist and found plenty to disagree. But

First some words on anonymity in general.

In an earlier post, I commented on anonymity in the blogosphere. Here too, I want to distinguish between anonymity and pseudonymity. The former is when the source of information is completely unknown, the latter is when the information is assigned to a name - a pseudonym - that is not connected to an actual identity but serves to address the person and also makes it possible to recognize them later. Most commenters on this blog are psydonymous rather than anonymous in that they have chosen a nickname and return with that same name.

I strongly discourage posting as "Anonymous" because as soon as there's two anonymousses in a comment section it becomes impossible to lead a decent conversation. In the long run, a pseudonym also allows me to learn what your background is and thus what reply to your questions might be useful. This saves all of us a lot of time and reduces misunderstandings.

Now back to Di Leo's essay against anonymity

Di Leo has a problem with anonymity of the peer review process. His main point is that "Anonymity is Anti-Dialogue," "Anonymous propositions are fundamentally monological, not dialogical," and that critical dialogue is the essence of progress in science. While this is correct, peer review is not actually anonymous but pseudonymous since the author can typically correspond with "reviewer 1" and "reviewer 2," mediated by the editor. Leaving that aside, Di Leo dislikes anonymity in general, and the one-sided anonymity of peer review in particular, since usually the reviewers know the identity of the author, but not vice versa.

Di Leo regards double-blind reviews in which the reviewer doesn't know the author's identity (which he calls "totally anonymous") as "not as problematic" as the standard partially anonymous peer review. However, as I said several times before, double-blind reviews are practically unfeasible in the 21st century. Not only because in an increasing number of fields papers can be found on pre-print servers long before they got published, but also because in specialized disciplines it isn't hard to figure out who wrote a paper on what topic. People have a distinct writing style (or absence thereof), and it is often not much of a secret what they have been working on recently. Let's thus forget about that option.

Di Leo then goes on to explain that "anonymous assessment is antithetical to the very idea of the academy," that "academia has created a culture and ethics of uncritical consent and has hidden it behind the cloak of collegiality," and further bold assessments about the status of academia. He writes

"The common rationale for academic anonymity is quite clear: if one were required to accompany one's assessment with one's true identity, one would not speak the truth."

So let me comment on this.

First, science is done by humans. We know that humans are not perfectly rational, and that the human perception and opinion making process is easily biased. Disregarding such weaknesses leads to disasters as you can see for example in the ailing status of our financial systems. You can talk about the "idea of the academy" all you like, we don't live in the world of ideas. Reality isn't ideal, and the reason why utopias of all kind fail is that they envision an unrealistic human behavior. The academic system shouldn't be build upon somebody's ideal for scientific dialogue but upon reality. If we have good reason to think that some reviewers might feel the need to pay attention to the author's status and their own relation to it if their identity was revealed, then we can bemoan they feel this need but denying its existence isn't helpful.

Second, I completely agree that critical dialogue is essential to science, that anonymity makes it impossible, and that pseudonymity hinders it. However, I don't think peer review is the place to lead that dialogue. Peer review is the place to decide what fulfills the requirements of being published in a certain journal as a certain type of article. More often than not, the dialogue is lead through these publications and not in the review process.

Third, nobody forbids the reviewer to contact the author of a paper and reveal their identity should they wish so; I actually know people who do that frequently. It is thus factually wrong to say the peer review process "prohibits or prevents dialogue" as Di Leo states. One main reason why many reviewers do not engage in more dialogue with the author is not that they are afraid of it, but simply that they don't have the time. There are weeks when I receive 3 or 4 requests for referee reports. I can't sensibly lead an extended conversation with all of these authors, otherwise I wouldn't be doing anything else. I read the paper, write my report, and that's it. Some of the authors I know anyway, and they know my opinion. If you manage to reduce the number of written papers by a factor 100 or so we can talk about extended dialogue.

Fourth, the above statement that reviewers would not speak the truth if their identity was revealed and thus something must be wrong with the community is only partly correct. I strongly doubt any serious scientist would deliberately omit pointing out factual errors in a paper, whether anonymous or not. But that is only part of the review process. There are many journals for which factual correctness is a necessary requirement but far from being sufficient for publication. What also matters is whether a paper is appropriate for a journal, and how interesting it is. And that is, like it or not, to a large extend a personal assessment. It might very well be you find a paper more interesting if it was written by a Nobel Prize winner and that isn't even irrational. It is this part of the assessment that might make the reviewer feel uneasy if it wasn't anonymous because it is socially and politically very involved. Sure, scientists shouldn't take it personally if some of their colleagues don't find their work tremendously exciting, but some do.

Di Leo also briefly comments on blogs and scientific debate

"If one, for example, posts on his or her blog a statement concerning one’s belief in gremlins, one is not obligated to respond to persons who disagree with this statement. However, in the academy, students, faculty, and administration are expected to answer to questions about their opinions."

While he means to point out the difference between blogs and scientific debates, he actually points out what's different between science and belief. You are not obligated to respond to persons who disagree with your believes, because you can believe whatever you want, may that be gremlins or the flying spaghetti monster. But that's not science. Likewise it's not science to ignore facts relevant to your research that have been brought into your attention, but it shouldn't matter by whom or where.

Where and from whom you obtained information might however affect how much attention you'll pay to it to begin with, and that is another reason against unnecessary use of anonymity. We live in the information age. Today's problem isn't obtaining information but filtering it, and the source of information is a very widely used and very effective filter.

Bottomline

Anonymity has its place in science, but it should be used sparsely and only if absolutely necessary. Anonymity has the disadvantage of making dialogue more complicated, I agree with Di Leo on that. But it has the advantage of avoiding unnecessary social and political baggage. I thus think anonymous peer review will remain essential to scientific publishing.

I would welcome however if the communication in the peer review process wasn't so cumbersome. It is feasible for example that the author and the reviewer lead a discussion without each exchange being mediated by the editor, eg in some interface similar to a chat. After some weeks, the reviewer could summarize his impression from the exchange. This would allow it to easily clarify some general questions or possible misunderstandings.

On the general theme, the problems Di Leo addresses are at the core caused by the four pressures that I have discussed here. Financial pressure, time pressure, peer pressure, and public pressure all skew scientists' opinions and make it necessary for them to pay attention to things other than their true scientific assesment. The solution is thus to reduce these pressures as far as possible.

Office Stuff

The other day I cleaned out my desk at PI. It is remarkable how fast clutter accumulates in offices, especially in places with a large turnover rate.

The desk drawers typically feature a selection of paper clips in all colors, sizes and shapes together with various other supply like colorful textmarkers, tippex, post-its, and undefined sticky substances. The first desk I got in a department of physics was passed on to be my by the previous only-women-at-the-institute. She nicely left some tampons. When I arrived at PI my desk drawer unit was full with my new office mate's files. It took me several months to convince him I really do need some space myself. (Nice girls don't only not get the corner office, they don't even get a desk drawer.) Looking into the bookshelf next to my desk, it was filled with notes and papers and folders and business cards from pre- and pre-decessors.

I changed office during my second year at PI due to an incurable disagreement with my officemate about what constitutes a life-friendly room temperature. This degraded me down to the 2nd floor where the view isn't so pretty, but also upgraded me to a window desk. While there was still plenty of space for my few things in the shelf, that office too already featured some folders and files of unknown origin, some filled, some empty. I also found a copy of Weinberg's first QFT volume that I happily used. It doesn't have any library stickers on it, and I have no clue whose it is. I'll leave it for whoever gets the desk next.

It is also always interesting what's under the keyboard or to check if there are sticky notes in the drawers. They will typically feature phone numbers, email addresses, or cryptic combinations of numbers and digits that probably are some of the dreaded random-generated keywords the insufficient human memory is sometimes forced to deal with.

And PI isn't even yet 10 years old! In the advanced stages, it will look like the ITP in Frankfurt did. Upon being shown your new desk, you realized all bookshelves were full already with books, papers, files and notes that had accumulated over decades and that nobody ever dared to throw out. After all, they belong to somebody, right? Offprints and proceedings seem to be particularly vulnerable to abandonment. The walls will be covered with helpful notes, like "if the phone doesn't work push the plug," or "if AC runs havoc call XYZ & chatter with your teeth."

And let's not even talk about hygiene. Shortly after I changed offices I accidentally spilled coffee on the floor. A full year later, the spills where still there. Acting out on a severe case of PMS I asked what the cleaning staff is actually payed for. Next day, the coffee spills where gone, but the floor is still covered with dead insects and spider webs in the corners. The occasional pencil stroke on the desk is also preserved for future generations. A study by the University of Arizona found the typical desk has hundreds of times more bacteria per square inch than an office toilet seat.

It's also amazing what people store in their offices. One prof I knew used to dry his bathing trunks in his office. Many have various sports equipment and clothes, towels, and shoes. I've also come across shaving supply, suitcases, plumber's helpers, silver- and dishware, condomes, ropes, empty pizza-boxes and leftover food in advanced stages of decay, plush toys, action figures, pillows, pet food, jumper cables, and toys, tools and technical equipment of all sorts. Somebody should make a movie about physicists being trapped in their institute, needing to come up with some ingenious construction to save their lives from what's to be found in their offices only.

I'm looking forward to my next desk :-)

That Photon from GRB090510

A brief comment on the recent paper

Testing Einstein's special relativity with Fermi's short hard gamma-ray burst GRB090510
By Fermi GBM/LAT Collaborations
arXiv:0908.1832v1 [astro-ph.HE]

which reports the detection of an high energetic photon of 31 GeV within the first second of onset of the Gamma Ray Burst (GRB) 090510. As I explained in earlier posts (here, here and here), some scenarios with Lorentz Invariance Violation (LIV) motivated by quantum gravity do predict an energy dependence in the travel time of photons. Over such long distances as ours to the origin of the GRB, tiny delays add up and can upon arrival of the photon in our detectors result in an energy-dependent modification of the signal. The case that has been favored in the last years is that photons with high energies would arrive later than the lower energetic ones even when emitted simultaneously.

Previously reported cases indeed indicated high energetic photons arrive with a measurable delay. The status of the constraints on LIV derived from these events was nicely summarized in Lee and Giovanni's recent paper. One has to keep in mind though, without a precise knowledge of the emitting source it is hard to tell whether a measured effect happened during propagation. Besides this, the LIV modification in the propagation of photons is only measurable if it is a first order effect (of order Energy/Planck mass). If it is quadratic or higher, the effect would be too small to affect the spectrum of GRBs.

To let you know what my stakes are on the matter, I don't find it plausible quantum gravity would affect the propagation of photons from GRBs. I wrote a paper on that some while ago that explains very clearly why. Without going to much into the details, whether or not quantum gravitational effects are relevant depends on the energy density, not the energy. The energy density even of the GRB itself, and certainly that of the traveling photons, is many orders of magnitude too small to cause any measurable effect. It adds to this that models with violations of Lorentz invariance do either break Lorentz invariance, on which there are strong constraints from many experiments already, or they "deform" Lorentz invariance (known as "Deformed Special Relativity"), which causes conceptual difficulties that are so far unresolved. For these reasons, I am not very convinced such a quantum gravitationally induced energy-dependence of the speed of light would be observable in GRBs. It is however an interesting and testable scenario.

In any case, the measurements of GRB090510 reported in the above mentioned paper do clearly not support the energy-dependence of the speed of light. In the paper, they derive a bound on the Planck scale from their measurements that is some orders of magnitude higher than we expect the Planck scale to be. This means if there was an effect it is much smaller than it should have been. However, it gives me the creeps if people draw conclusions from single photons. As also Lee and Giovanni pointed out explicitly in their paper, the propagation could have a stochastic component since it's a modification caused by a quantum gravitational effects of the background. In that case, only more statistic could allow conclusions. It also remains to be explained what caused the delay in the other measured gamma ray bursts.

Thus, stay tuned...

[Via Stefan via Lubos].

News from Other Worlds

This week, I came across some quite amazing news about planets at other stars in our galaxy. But it's not just the stories of planetary collisions and retrograde orbits that have fascinated me: It's also how all this has been learned, by closely analyzing light curves and spectra. So, here are a the plots behind the news:

Direct light from an extrasolar planet

So far, extrasolar planets have mainly been detected indirectly - by dimming the light of the star during transit for example, or by a periodically changing Doppler shift. It's very hard to see the light reflected by the planet itself. This week, the Kepler team has reported clear evidence of the light form planet HAT-P-7b, in orbit around a star in the constellation Cygnus. Here is the proof:


Light curve of the parent star of planet HAT-P-7b, shown over a bit more than one period. From Kepler’s Optical Phase Curve of the Exoplanet HAT-P-7b by W. J. Borucki et al., Science 325 (7 August 2009) 709.
The figure shows the light curve of the parent star, its apparent luminosity over a time span of about three days. As can be seen in the upper figure, the luminosity drops very clearly by about 0.6 percent every two days or so - that's when the planet transits in front of the star, and darkens a bit its disk.

But wait - there is a second slight dip in the light curve right halfway in between two eclipses. Looking at the curve on another scale in the middle of the figure, we see that the luminosity gently increases and decreases by 0.01 percent over one period, with a marked drop back to "normal" in the middle.

This gentle variation of the light curve comes from the light reflected by the planet! The drop in the middle occurs when the planet is hidden behind the star on its orbit.

If only it was possible to detect such small changes in the spectrum of the light, it may tell interesting stuff about the planet.

Planetary collisions at HD 172555

Speaking of spectra... The Spitzer Infrared Space Telescope has observed a dust cloud around the star HD 172555 in the southern constellation of Pavo. The resulting spectrum of infrared light can best be understood by assuming that quite a dramatic planetary collision has happened at this star a few thousand years ago.


Infrared Spectrum of the dust disk around star HD172555. From Abundant Circumstellar Silica Dust and SiO Gas Created by a Giant Hypervelocity Collision in the ∼12 Myr HD172555 System by C.M. Lisse et al., Astrophys.J. 701 (2009) 2019-2032, arXiv:0906.2536v2
The spectrum - the black, noisy curve - shows a general blackbody shape, with additional features that are typical for silicate particles.

Silicates, the matter of sand and dust, contain silicon-oxygen bonds that produce infrared bands whose shape and location also depend of the specific crystal structure, and thus are very characteristic for the different types of silicates. A unique feature in the infrared spectrum of the dust cloud of HD 172555 is the sharp peak at a wavelength of about 9 micrometre. This peak can be understood as produced by a mixture of mainly two types of silicates, tektite and obsidian.

There is something special about these two silicates: They are glass-like, and they are produced by melting and rapid cooling of other silicates materials. Tektite is a telltale sign of the impact of large meteorites on the Earth's surface.

Now, for finding such large amounts of tektite and obsidian in the dust cloud of HD 172555, there is just one plausible explanation: There must have been a collision of Moon- to Mercury-sized planets orbiting the star, similar to the collision that happened to the early Earth which is supposed to be the origin of the Moon!


Retrograde planet WASP-17b

A collision might also have caused the retrograde motion of planet WASP-17b, which orbits star WASP-17 in the constellation of Scorpius.

One usually assumes that a star and its planets originate by collapsing from the same rotating cloud of dust. Hence, the rotation of the star and the revolution of its planets should be in the same sense - the spin of the star and the angular velocity of the planets should be parallel. This is the case, for example, for all the planets in the solar system. A planet revolving "in the wrong direction" is called retrograde.

Surprisingly, it is possible to check if the revolution of a planet is normal or retrograde if the planet transits the star. Due to the rotation of the star, one half of it has a component of motion towards our line of sight, while the other half is moving away from us. This implies a Doppler effect towards the blue and to the red for the different halves of the disk of the star, respectively. When averaging over the whole disk of the star, this results in a broadening of the spectral features. But when a planet transits the star and thus blocks parts of its light, a net Doppler effect can bee seen. This is the so-called Rossiter-McLaughlin effect.


Doppler shift of the light from star WASP-17 during the transit of its planet, WASP-17b. From WASP-17b: an ultra-low density planet in a probable retrograde orbit by D. R. Anderson et al, arXiv:0908.1553v1.
The curve shows the Doppler shift of the light from star WASP-17, measured with the CORALIE spectrograph shortly before, during and after the transit of its planet WASP-17b. If the planet revolves in the same direction as the star rotates, there should first be a net redshift: The planet appears in front of star on the side which is moving towards us, thus blocking the blueshifted light. For the analogous reason, there should be a net blueshift at the end of the transit. This "normal situation" corresponds to the grey, dotted spike-like curve in the figure.

But the data points evidently fit much better to the opposite case: First a blueshift, then a redshift. This is the sign of a retrograde orbit!

I do not know if there is more than mere speculation as to what has happened to planet WASP-17b in the past to make it revolve in "the wrong direction" - but maybe we can learn more from future spectra.

... and a meteorite on Mars

After all these abstract curves which have such vivid interpretations, here is very concrete photo (thanks to Andi for the link):



It is an iron meteorite, lying on the surface of mars, and stumbled upon by the Mars rover Opportunity.

Without any detailed spectroscopy, it also seems to tell us something: When the meteorite fell on Mars, the Martian atmosphere must have been much denser than it is today, because otherwise the impact on ground would have been strong enough to destroy the meteorite and create a big crater.

---

TAGS: astronomy, spectroscopy, extrasolar planet

Four Stages of Science

In the comments to our recent post And how open would you want your science? Arun pointed out an interesting paper

Four stages of a scientific discipline; four types of scientist
By Alexander M. Shneider
Trends in Biochemical Sciences
Volume 34, Issue 5, May 2009, Pages 217-223

In this paper, Shneider suggests to distinguish four different stages of a scientific discipline, that I will briefly summarize below. It is somewhat ironic the author writes he believes "this analysis could be instrumental for individual researchers in their career planning," but then publishes his paper in a subscription journal that wants to charge you US $ 31.50 for a 6 page article.

The identification of different stages through which a research program goes is an approach that resonates with me. I have been previously referring to this vaguely as "the stage of creative process," and have pointed out many times that there can be no overall prescription for what amount of "transformative" and "conservative" research a discipline needs that does not take into account different fields are in different creative phases. Thus any call for more support of one or the other research style is an oversimplified panacea that might or might not work in one or the other case.

However, though Shneider's paper is interesting, I don't find it very well thought through. In particular, the author tends to speak of the characteristics of a "science" and of "scientists," though I doubt these ever occur in a pure form. It would be more useful to characterize a specific research project, and then identify the stage of the discipline by what sort of projects are mainly pursued, or similarly characterize a scientist by what sort of projects he mainly works on. You also wouldn't call a restaurant or its cook "spicy," you'd call a dish spicy and then say the restaurant offers many spicy dishes, and the cook is known for them.

In any case, here the characteristics of the four stages:

Stage 1:

• Introduction of new subject matter
• New scientific language
• Often based on new observations and/or experimental results
• First stage scientists not necessarily the ones who discover new facts
• First stage scientists often need to be somewhat imprecise or inaccurate because not all necessary facts are known or properly comprehended
• Theory often contains uncertainty
• First stage scientists do not always possess exquisite technical skills.
• Philosophical, aesthetic and cultural views, analogies and literature are instrumental to the first stage scientists' mode of thinking

Stage 2:

• Development of major techniques
• Often re-applications of methods previously developed in another discipline (plus rethinking and adjustments to new task)
• Main characteristic of second stage scientists are ingenuity and inventiveness, an ability to implement ideas and a high risk-tolerance

Stage 3:

• Most of the actual data and useful knowledge is generated
• Re-description of subject matter, creation of new insights and questions
• Difficulties and unexplained phenomena often give birth to new first stage
• Most useful personal qualities of third stage scientists are detail oriented, neat, hard working
• Extensive knowledge of philosophy or art is not instrumental

Stage 4:

• Communication and carrying on of knowledge
• Reviews, organization of knowledge
• Without the fourth stage scientists, the explosion of new data generated at the third stage would be chaotic
• Development of applications
• Re-evaluation of the role of the discipline in a possibly changing social and cultural context
• Forth stage scientists use a broad spectrum of cultural and philosophical views
• Forth stage work serves to inspire new generations of scientists

The paper also has some remarks on how these four stages relate to Kuhn's theory of scientific revolution. The author points out that Kuhn was aiming at characterizing paradigm shifts, not the life-cycle of scientific disciplines.

I think one should consider that a discipline might run into a case of arrested development in any stage, in which case too much effort goes into the wrong research direction. Unfortunately, such cases might become self-supporting due to the present organization of the academic system in which people go where money goes, and money goes where people go. This leads to the formation of the scientific analog to economic bubbles. As a result, the amount of people working in a field does not accurately reflect its actual promise.

Shneider provides many examples, but these are dominantly from past centuries and from biology and chemistry. If you have a current example, leave it in the comments.

Interna

My move is slowly making progress. Meanwhile I'm getting increasingly edgy because I haven't had time to do as much as read a single paper for almost a week. I think I have withdrawal symptoms.

I managed to sell almost all of my furniture, except for a lonely armchair that hasn't found a new friend yet. The woman who bought the bed luckily doesn't need it before next month. She agreed to pick it up the day I'm leaving so I won't have to sleep on the floor. I washed and vacuum cleaned the car and put "For Sale" signs in the windows. Today somebody took a testdrive and said he's very interested and will get back to me.

The moving company is scheduled to pick up my stuff in 10 days. From here it goes to the East Coast, on a ship and over to Europe. I'm told the port of first entry will be in the UK. Luckily, unlike in Canada, I don't have to appear in person at customs. (Though customs Canada was more or less a joke. After my household items arrived, I had to appear at customs at the closest airport. A women asked if I had imported any weapons. When I correctly replied "No," she stamped my documents, said "Welcome to Canada," and that was that.)

In the UK the stuff will go back on the road and then I don't know. Moving companies, I had to learn, work in mysterious ways. In particular, they like to collect sufficient stuff to get a truck full. My things don't fill an 18 wheeler, thus they are likely to sit around in various European cities for an undetermined amount of time.

Sorting through my stuff, I found a lot of notes for topics I meant to blog about but then didn't. I also found a napkin ring that I absendmindely played with and then took with me first time we went to dinner at Hannah's. Hannah's used to be the best restaurant around, but it closed recently.

If you have ever been in Waterloo, you will have seen its landmark, a pyramid of barrels in front of the old Seagrams Distillery (which now hosts the Center for International Governance Innovation). It's just opposite Perimeter Institute. The pyramid has been removed in the last days to make place for something called the "Balsillie Centre of Excellence," about to be build there. Residents could come and pick up a barrell, I hear the barrels were gone pretty fast; more than 500 were distributed to members of the community.

Perimeter Institute itself is also in the middle of changes. The constructions for the building extension have begun. Most of the parking lot is closed, fenced and filled with fancy working equipment. It is also the time of the year when new people come in and the expired folks, like me, go out.

I'm sitting in my apartment, surrounded by moving boxes, trash, and piles of unsorted papers. I've cancelled my electricity, water, and internet services. I've handed in my notice to move out. I dealt with the insurances, the automobile club. It feels like I just yesterday opened the bank account, now I'm trying to find a smart way to close it. Inbetween, I'm trying to learn a few words of Swedish. En, tva, tre, fyra, fem, sex, sju, atta, nio, tio. Jag talar bara lite svenska. I haven't figured out yet how to get the little circles over the vowels.

Things are changing. It's kind of comforting this blog stays the same.

This and That

• Clifford Johnson now makes into movies.


• For those of you who speak German: the German Science Foundation (DFG) now features video clips of scientists reporting on their research. As amusing as informative. (Thanks to Andi!)


• The Quark Matter, the largest regular nuclear physics conference, awarded this year a "Young Scientist Award," which went to Sarah LaPointe for the best poster presentation and to Mateusz Ploskon for the best oral presentation. I think such an award is a lovely idea. Makes me a little nostalgic, since I won the poster award at the Quark Matter 2004.


• The previously mentioned Quantum to Cosmos Festival in honor of PI's 10th birthday has a blog.

Röser's equation, again

Over the weekend, I thought again about Röser's equation relating the transition temperature of high-temperature superconductors to a characteristic length scale called "doping distance". Having reread the Proceedings paper where it is described, I wanted to add a few comments to our last week's post, only to realize that blogger has a restriction to the length of a comment. So, here is a second post.

Let me just repeat the main point of the "Röser formula":

It claims a simple linear relation between the inverse of the superconducting transition temperature of a wide range of superconducting materials, and a so-called "doping distance". This relation is shown in the following plot:


(from: A Correlation Between Tc of Fe-based HT Superconductors and the Crystal Super Lattice Constants of the Doping Element Positions by Felix Huber, Hans Peter Roeser, Maria von Schoenermark, Proc. Int. Symp. Fe-Pnictide Superconductors, J. Phys. Soc. Jpn. 77 (2008) Suppl. C, pp. 142-144)

Here are a few more thoughts of mine about this relation.

Thermal de Broglie wavelength

Using the standard definition of the thermal de Broglie wavelength for a Cooper pair of two electrons with free masses, the Röser equation

4 π k m_e(2 x)² n^−2/3 = h²/ T_c

actually boils down to

(2 x) × n^−1/3 = λ_c

where λ_c is the thermal de Broglie wavelength of the Cooper pair at the critical temperature T_c, where superconductivity breaks down.

In the proceedings paper, n = 1, so the factor n^−1/3 can be dropped. Moreover, it is said to take values of n = 2 or 3 for other superconductors with a layer structure, depending on the number of layers in the unit cell. It's not completely clear to me how it is motivated.


Substances Covered

In the proceedings paper, the authors discuss doped iron arsenides LO(1−Δ)F(Δ)FeAs, where L is a rare earth, L = La (Lanthanum), Gd (Gadolinium), Ce (Cerium), Pr (Praseodymium), Nd (Neodymium) or Sm (Samarium) - see table 1 of the paper. These materials are labeled as "LOFFA", "GOFFA", "COFFA", "POFFA", "NOFFA", and "SOFFA" in the plot.

The other data points in the plot refer to cuprate superconductors - the substances labeled ...CO, or Bi-2212, where the numbers denote the composition. These cuprates are discussed in several Acta Astronautica papers, for example Acta Astronautica 65 (2009) 489, which unfortunately I do not have access to.

Doping

In the examples of the rare earth iron pnictides, superconductivity can be reached by replacing, in an ideal LOFeAs lattice, some of the oxygen atoms by fluorine atoms. Depending of the amount of fluorine, the critical temperature for superconductivity can take different values. The Physics article on High-temperature superconductivity in the iron pnictides shows phase diagrams for "LOFFA" and "COFFA".

In "COFFA", CeO(1−x)F(x)FeAs, for example, superconductivity sets in only when at least 6 percent of the oxygen atoms are replaced by fluorine, and the transition temperature is highest for a replacement of about 16 percent of the oxygen atoms by fluorine:


(from: Structural and magnetic phase diagram of CeFeAsO(1-x)F(x) and its relationship to high-temperature superconductivity, by Jun Zhao et al., arXiv:0806.2528v1, and Nature Materials 7 (2008) 953-959.)

The percentage of replaced atoms is called the "doping", and it is usually denoted with x, which should not be confused with the "doping distance" in the Röser paper. In the formula above for the substances, I have denoted doping with Δ, as in the Röser paper.

The "doping distance" x

The Röser formula compares the thermal de Broglie wavelength of a Cooper pair at the superconducting transition temperature with a "doping distance" x and states that they are equal, up to a geometry factor. The crucial point, then, is how to arrive at the "doping distance".

In the proceedings paper about iron arsenides, it is argued that every two of the "doping" fluorine atoms group around one iron atom, and that these "decorated" iron atoms form, again, a regular lattice. Such a lattice is usually called a superstructure.

In the example of "COFFA" at the "optimal" doping of Δ = 0.16, this reasoning implies that 8 percent of the iron atoms are neighbored by two fluorine atoms each, and the superstructure of the decorated iron atoms has to comprise 1/0.08 = 12.5 standard unit cells. They argue that this means that 5 unit cells are put on top of each other, yielding a doping distance of 5 times the height c of the unit cell, or x = 5 c.

For the other doped lanthanide iron arsenides, a similar reasoning is used. The constructions of the superstructure and the resulting doping distances are documented in table 1 of the proceedings paper.

Open questions

To me, construction of the "doping distance" is not really comprehensible, and it seems that there are a few points where the paper just glosses over:

I am not sure whether (1) the dopant fluorine atoms group pairwise at iron atoms and (2) if the decorated iron atoms indeed form a superlattice. However, this may be checked experimentally. But then, (3), if there is a superlattice, it is not clear to me why it should be ordered in the way claimed in the paper, with a pattern stacking five unit cells on top of each other for "COFFA", for example. There can be many ways to arrange unit cells to form a superlattice with the right supercell volume. This is more obvious in the case of "LOFFA", where the supercell comprises 18 unit cells, and there seems to be no a priori reason to select a superstructure which has 6 unit cells stacked on top of each other.

In other words, the determination of the "doping distance" involves an arbitrariness which may be used to select x in a way to fit the formula, and there is no real discussion of the selection rules in the paper. This arbitrariness, however, could be resolved by experiments which actually measure the superstructure.

There is another point which puzzles me about the paper, which is the application of the formula to the cases of "optimal doping" only, i.e. those values of doping where the transition temperature for the substance at hand is maximal.

I don't see a good reason why the formula should not apply at any value of doping, if there is a relation between the transition temperature and the "doping distance". Then, however, there is the problem that around the maximum, different values of doping give the same transition temperature, hence should have the same doping distance. This can be seen very nicely in the phase diagram of "COFFA" above. Maybe this point can be arranged for somehow, and maybe it is discussed in the Acta Astronautica papers.

Conclusion

Thinking about it, while the Röser relation is indeed amazing, it's unclear to me how much of an "a posteriori" selection bias concerning the "doping distance" goes into it.

However, as the relation makes strong claims about the arrangement of the dopant atoms, this probably can be checked experimentally.

If it comes out that the relation indeed holds, it will be exciting to understand what it means for the physics of superconductivity.

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• The August 2009 issue of the Scientific American gives a nice overview of superconductivity in iron pnictides in the article An Iron Key to High-Temperature Superconductivity? by Graham P. Collins (albeit without illustrations, it seems...)


• Browsing the APS' Physics Archive for the tag superconductivity is a good way to keep up-to-date with the developments in the iron pnictides.

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And how open would you want your science?

I just read Dan's recent post "What, exactly, is Open Science?" He names four fundamental goals of open science:

• Transparency in experimental methodology, observation, and collection of data.
• Public availability and reusability of scientific data.
• Public accessibility and transparency of scientific communication.
• Using web-based tools to facilitate scientific collaboration.

These seem to be rather experimentally focussed, so let me add some words from the perspective of a theorist. Since I just finished reading Surowiecki's "Wisdom of Crowds" (see review), I feel now better equipped to get across something I already said in my post We Are Einstein, so let me quote myself and then explain:

"[A]n environment with a very high interaction rate thermalizes quickly, and can be very destructive in the early stage of an idea's development. A highly connected community means we’ll have to watch out very carefully for sociological phenomena that might affect objectivity, and work towards premature consensus. We will have to watch out for fads that grow out of proportion, and we will have to find a way to protect the young ideas that “you have to ram down people's throats,” in Atkin's words, until people are ready to swallow them. There is no reason to assume scientists are immune to sociological effects."

With the wisdom I gathered out of Surowiecki's book, the point I was trying to make is that sharing too much information and being too tightly connected will actually lead to a dumb rather than a smart community.

Yes, that is right. What I am saying is that all the sharing and openness can actually harm progress. In fact, I think we already share way too much too premature information. The reason is that scientists too are only human. If we hear some colleagues talk who are genuinely excited about a topic, chances are we'll get interested. If we have an idea in an early stage and bounce it off a lot of people, it will lose its edges because we'll try to make it fit. If we hear something repeatedly, we are likely to think it's of some relevance. If we know the opinions of other people, in particular people with a higher social status or more experience, we'll try to fit in. That's what humans do. That's why crowds make dumb decisions. That's how groupthink starts, that's where herding comes from, that's how hypes and bubbles are created. As Surowiecki points out, independence during the opinion making process is essential for an outcome that reflects all the wisdom present in the crowd.

Of course nothing of that applies to you, the superior and entirely rational scientist, because you are different. Funny though that study after study shows scientists are just like all other people.

Dan writes in his post that he wants the incentive structure to be changed such that it supports openness. With that he means "Work. Finish. Publish. Release." Again, this seems specific to experiment (a theory is released when it's published). I do of course agree on the goal, but not on the means. I am generally suspicious about any "incentives" that are supposed to push scientists into doing something they wouldn't voluntarily do. We do have such incentives today. And they are counterproductive. I don't want them to be replaced with other incentives that somebody cooked up on his blog and that likely turn out to be equally counterproductive, though for other reasons. That's why I say the only thing we have to rely on is our own judgement and what we should be doing is to avoid any distortion of the opinion making processes. And for that, we should be paying attention to what advice our colleagues from psychology and sociology have to offer.

Sometimes when I hear Science2.0 fans fantasize about the brave new world they want to create, one in which every scientist throws his thoughts into a vast global pool of knowledge and thousands colleagues contribute and advise, I get really scared. For all we can tell from current knowledge, the result will be a combination of streamlining and self-supporting fads. What scientists really need is more time and more freedom to play with their ideas without pressure to fit in, to publish, to make up their mind.

Thus, my bottomline is always the same: You can dream up any 2.0 utopia you want. But in reality it will be populated with imperfect, irrational humans. If you're not taking into account well studied sociological and psychological effects your utopia will be a dystopia. Science can be too open.

Book Review: “The Wisdom of Crowds” by James Surowiecki

“The Wisdom of Crowds”

By James Surowiecki
Anchor; Reprint edition (Aug 16 2005)

James Surowiecki’s book is an entertaining summary of many, recent and not so recent, studies on crowd behavior. The book comes with many references, and provides quite a balanced assessment of current knowledge. Unlike what the title might suggest, Surowiecki’s book is not a praise of “The Wisdom of Crowds,” but rather an examination under which circumstances crowds are wise, and for which purposes this wisdom might be useful.

Surowiecki distinguishes between three different problems posed at a crowd: problems of cognition, coordination and cooperation. The book is divided into two parts. The first part offers a lot of examples for these problems and the crowds’ attempts to solve them. The second part looks into the question which conditions are necessary for a successful solution. The author identifies three such conditions: diversity, independence (of individuals from each other), and decentralization – though with qualifiers:

“[D]ecentralization works well under some conditions and not very well under others. In the past decade, it’s been easy to believe that if a system is decentralized, then it must work well. But all you need to do is look at a traffic jam – or, for that matter, at the U.S. intelligence community – to recognize that getting rid of a central authority is not a panacea. Similarly, people have become enamored of the idea that decentralization is somehow natural or automatic. [However,] it’s hard to make real decentralization work, and hard to keep it going, and easy for decentralization to become disorganization.”

This paragraph makes clear that understanding the ways crowds make decisions is necessary to set up a system such that decision making is smart. Intelligent organization requires thinking – and scientific research.

Surowiecki warns of factors that dumb down the decisions of groups, most notably skewing information, groupthink, and herding, all of which lead to suboptimal decisions, and potentially disastrous failures.

The cases discussed in the book draw on many examples, the recurring ones are betting markets, and the financial and economic system. The author also dedicates a chapter to the academic system, and ends with discussing politics. While the elaborations on the financial markets are extensive and insightful though somewhat repetitive, those on politics are well meant but vague, and those on academia are hopelessly naïve:

“The coin of the realm, for most scientists, is not cash but rather recognition. Even so, scientists are undoubtedly as self-seeking and as self-interested as the rest of us. The genius of the way science is organized, though, makes their self-interested behavior redound to the benefits of all of us. In the process of winning notoriety for themselves, they make the group – that is, the scientific community and then, indirectly, the rest of us – smarter.”

The chapter comes with very few, basically irrelevant references, and leaves me with the impression the author has next to no experience with academic research. Unfortunately, “the genius of the way science is organized,” is today severely affected by various pressures researchers are subject to in their decision making process, most notably financial and time pressure. That, together with, herding, lacking independence, a meanwhile completely thermalized information basis, and specialization and fragmentation which promotes groupthink, several of the factors Suroviecki previously identified as necessary for smart decision making are not fulfilled. And that doesn’t even touch on the question how well the “smartness” of the scientific community reaches “the rest of us.” For more details, see my post We have only ourselves to judge each other – which suggests the steps to be taking to allow the scientific community to be indeed a decentralized, smart crowd.

A central theme of “The Wisdom of Crowds” is that leadership by a single or few persons is unlikely to be superior to using the full available knowledge (of the group, the company, the community, ie the crowd). Humans tend to assign success and failure to single persons where it might instead have been simply a result of lucky or unlucky circumstances. A consistently better performance, so the author argues, cannot be achieved by picking “the” right person, but by accessing and aggregating the wisdom of the crowd.

It remains somewhat unclear throughout the book what role Surowiecki assigns to experts, though he writes in the afterword that the expert is of course necessary to provide information, for without information neither a crowd nor anybody else can make qualified decisions. He cautions however that many studies have shown that specialists - as all other people - tend to be overconfident about their knowledge and fall for the “Illusion of Knowledge,” ie they fail to see the limits of their own knowledge. If the role of the experts is to provide the crowd with information, then one should keep in mind that the way how information is communicated can spoil the ability to make good decisions, eg by making information seem more (or less) important than it actually is, or by attaching irrelevant details like what specific persons thought about it. (And let’s not even talk about the problem of simply inventing information.)

In any case, the book makes a very compelling case that there is a large unused potential in the wisdom of crowds and that, if we know how to tap onto this potential, we could use it to improve decision making processes in certain situations. Especially scientists as members of large communities, and as members of academic institutions, can learn a lot from better understanding under which circumstances which decision making processes have been successful. The book conveys an optimistic, but also a cautious message, since there are many examples of stupid crowds as well. While the examples in the book fit very well into the argument the author is leading, I am (as often) left to wonder whether there are examples that did not fit into the theme and thus are not to be found in the book.

All together, “The Wisdom of Crowds” is a very recommendable book, informative and well written. If this was an Amazon review, I’d give five stars.

Read my other book reviews.

Röser's equation

At low temperatures, some materials display a feature known as "super-conductivity" - the total loss of electric resistance. Electrical currents in such a material, once initiated, propagate ideally forever. Super-conductivity sets in at a so-called "jump temperature," below which the material changes its electric properties. "Low" temperature in this case means indeed very low: The phenomenon was first observed on mercury with a jump temperature of only 4.19 Kelvin. Other jump temperatures for metallic compounds reach up to 23 Kelvin in Nb₃Ge. Bardeen, Cooper and Schrieffer got a Nobel prize in 1972 for their theoretical explanation of super-conductivity in these materials.

These temperatures seem way too low to ever make super-conductivity useful for daily life. But over the last two decades an increasing amount of substances has been discovered, the so-called "high temperature supra-conductors," (HTS), starting with the discovery of super-conductivity in barium lanthanum copper oxide at 35 Kelvin by Georg Bednorz and K. Alexander Müller in 1986, to the recent class of so-called iron pnictides.

For them, the jump temperature can be much higher, typically above 30 Kelvin, with the current record at 138 Kelvin hold by a ceramic oxide containing thallium, mercury, copper, barium, and calcium. However, this search has up to now been rather erratic with groups of researchers more or less systematically testing promising classes of laboratory-grown crystals. The jump-temperature of a crystal so far could not be predicted.

It is then quite astonishing that Hans-Peter Röser, professor at the Institute of Space Systems at the University of Stuttgart, Germany, found a simple equation relating the geometric structure of a crystal to its jump temperature. Röser's equation for the (critical) jump-temperature T_c reads

4 π k m_e(2 x)² n^-2/3 = h²/ T_c

where k is Boltzmann's constant, h is Planck's constant, m_e is the electron mass, x is the doping distance of the crystal and n is the number of supra-conducting layers in the crystal (it is usually 1,2, or 3). If one plots these quantities for known HTS one obtains the following graph, where the straight line is the prediction of Röser's equation:


(from: A Correlation Between Tc of Fe-based HT Superconductors and the Crystal Super Lattice Constants of the Doping Element Positions by Felix Huber, Hans Peter Roeser, Maria von Schoenermark, Proc. Int. Symp. Fe-Pnictide Superconductors, J. Phys. Soc. Jpn. 77 (2008) Suppl. C, pp. 142-144)

Now, neither Stefan nor I are specialists in super-conductivity, but this relation is quite interesting for it may harbor the possibility to better direct the search for high-temperature supra-conductors. Though one is left to wonder whether there is a way to know if a material will be super-conducting at all, it is intriguing how well the data points fit to the curve. It is however not clear to us whether the above shown curve depicts all known data points or only those that fit nicely, and how big the uncertainty of the quantity x is. In any case, the proposed relation is purely heuristic, it was obtained from accumulated data rather than derived from a theoretical model.

The relation was published in Acta Astronautica 62 733-736 (2008) and J. Phys. Soc. Japan Suppl. C 77 142-144 (2008).

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Update: Check out also the continuation of the post, Röser's equation, again

Copernicium and the Island of Heavy Nuclei

The Heavy Ion Society (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany, has dedicated its mission to slamming together heavy nuclei to produce even heavier nuclei.

For that purpose they use UNILAC, the 120-meter long Universal Linear Accelerator which accelerates ions to 20 percent of the speed of light to smash them on lead targets, and SHIP, the Separator for Heavy Ion reaction Products, an electromagnetic separator and detector assembly which is used to analyse the reaction products.

During the last decades, the GSI has thus become known with their discovery of new chemical elements in the periodic table. The latest one, element 112, has now been named "Copernicium," after astronomer Nicolaus Copernicus.

Previous ones were named Bohrium (element 107, named after Niels Bohr), Hassium (element 108, after the Latin name for the state Hesse, where GSI is located), Meitnerium (element 109, after Lise Meitner), Darmstadtium (element 110, after the city Darmstadt), and Roentgenium (element 111, after Wilhem Röntgen). These elements have a half-life ranging from seconds to minutes.

The element 112 (112-277) has been produced for the first time in fusion reactions of zinc-70 (with proton number 30) projectiles with lead-208 (proton number 82) targets. In a three weeks' experiment which ran 24 hours per day, one nucleus of element 112 was first observed on February 9, 1996. The nucleus disintegrates in a series of α-decays, which allows its identification:



The half-life of the new element Copernicium is not yet clear due to lacking statistics. But the discovery could be reproduced in other laboratories in Russia and Japan. Here is a photo of the proud discoverers (Credits: A. Zschau, GSI):



Sigurd Hofmann, the leader of the SHIP group at GSI, has given a talk about these dicoveries at the American Chemical Society meeting in San Diego, in 2001, to which you can listen here.

Besides the fun it brings to slam together heavy things, these experiments have the scientific purpose of better understanding the structure of elementary matter. Eventually, you know, physicsts want to derive all chemistry from QCD, but we're far away from that. The heavy ion beams produced at the GSI have also been used since 1997 for cancer treatment.

One theory that has been around for several decades is that at sufficiently high number of protons and neutrons the stability of elements will increase dramatically. In the periodic system, this patch has been dubbed the (conjectured) "Island of Heavy Nuclei." Its position shifted a bit with new models for nuclear structure, but it's still believed to be there, somewhere above atomic number 120.

I've always found this intriguing. Imagine, once we've crossed the valley of short-lived elements, we could produce some elements stable enough to form molecules and create chemical reactions that aren't taking place by natural processes anywhere in the known universe. Granted, serious nuclear physicists don't believe they would be that stable, but likely undergo spontaneous fission. But still, it would make for a nice science-fiction scenario, wouldn't it? A completely new kind of chemistry.

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The New Element 112.
Zeitschrift für Physik A 354, 229-230 (1996), DOI 10.1007/BF02769517.

This and That

• Next Wednesday, July 29th, the The MaRS Centre, in Toronto will be hosting an event about Science 2.0 "What Every Scientist Needs to Know About How the Web is Changing the Way They Work," More information here. [Via Jen]


• The Anacapa Society, dedicated to providing networking opportunities for theoretical physicist based at primarily undergraduate institutions, has found a permanent residence at Amherst College, Massachusetts, USA. They will also be holding a first workshop for theoretical and computational physicists this summer, August 17-20. [via Arjendu]


• This weekend, scientists from the Helmholtz research centre DESY, in Hamburg, Germany, generated the first X-ray light for research at the new synchrotron radiation source PETRA III. This means that the most brilliant storage ring X-ray source in the world is now available for experiment operation. Full press release here. [Thanks to Stefan]


• Elsevier is redefining the scientific article. [via James Dacey]

Hello from Stockholm

Loyal readers of this blog know that I'll be moving to Stockholm in September. I was thus looking for an apartment in the vicinity of the Swedish capital the previous days. If you haven't been in Stockholm before, it is definitely worth a visit. It is a culturally very interesting city and charming in addition. The below photo was taken South-East of the City Hall (exactly here).



And this is the view from inside the City Hall



This is one of the narrow streets in Gamla Stan



And here is a random green near the place where I'll probably be moving, just because the photo turned out to be really nice

Hubble 3D

The IMAX Corporation, NASA and Warner Bros. Pictures are working on a 3D movie about the Hubble telescope. According to the blurb "it will chronicle the amazing saga of the greatest success in space since the Moon Landing. Featuring stunning on-orbit coverage of the telescope's final repair and jaw-dropping IMAX 3D flights through distant galaxies, Hubble's astonishing legacy will be captured for generations to come." It is scheduled to be released Spring 2010. More information on this website. Here is some amazing video clips from YouTube that might or might not be related to the movie

What is Fundamental?

As previously mentioned, I was recently at the FQXi conference on the Azores. FQXi, the "Foundational Questions Institute," has the mission "to catalyze, support, and disseminate research on questions at the foundations of physics and cosmology." I work at an institute whose research is "devoted to foundational issues in theoretical physics." Fundamental, foundational, basic – what do we mean with that? What should we expect from a fundamental theory? What are the foundational questions? This was one of the questions we discussed at the FQXi conference, and while several of the participants contributed, I don’t want to blame any of them for the following summary.

So what is Fundamental?

A theory is fundamental if it cannot be derived from another, more complete, theory. More complete means the theory is applicable to a larger range. Note that a fundamental theory can be derivable from another theory if both are equivalent to each other (though one could plausibly argue then one should consider both the same theory).

Throughout history, the search and discovery of more fundamental theories in the natural sciences has lead to a tremendous amount of progress. That however is not a guarantee it will continue to be the path to progress. The issue is in the expression “cannot be derived” which could mean three different things:

Cannot be derived, version I: not possible in principle.

It might not be possible because it is not possible. Believers in reductionism think this is not the case for the laws of Nature we presently know: they should all follow from one most fundamental "Theory of Everything." While it is true that reductionism proved to be very useful and we thus have good reasons trying to continue it, there is no knowing the laws of Nature always allow a reduction. We would then be left with layers of theories that describe Nature on various scales that cannot ever be derived from each other, and thus have to be considered equally fundamental. While we presently don’t have evidence for this, it is a self-consistent point of view.

In the previous post on Emergence and Reductionism, I explained this is known as “strong emergence:” Emergent features on a higher level require a theory that cannot be derived from the underlying one. We previously discussed the paper “More really is different,” in which Gu et al offer an example for a system that does have emergent features, but it can be proved these are not derivable from the underlying theory. Granted, the system they consider isn’t particularly natural (see discussion on earlier post), but it gives you an impression of what this case means.

Cannot be derived, version II: not possible in practice

It might not be possible to derive emergent features from a more fundamental theory because of practical constraints. For example, it might take more computing power than we will ever have available, or more time than the lifetime of the universe to do it. It might take infinitely precise knowledge of initial conditions; it would make it necessary to measure parameters more precisely than we can plausibly expect ever; it would take a detector the size of the galaxy; etc etc.

Cannot be derived, version III: not yet possible

We might simply not have a derivation because we are too dumb the current knowledge isn’t sufficient, but we might find a derivation with more research.

Okay, now what is fundamental?

The problem is that at any one time we might not know which of these 3 cases we are dealing with. The exception is if we had an actual proof for the impossibility of a derivation. (But then a proof is only as good as its assumption.) We are thus left with our assessment of the situation, which might change with better understanding of the theories we have. In some cases there is a pretty clear consensus on whether a law is fundamental, in other cases it might not be so clear.

Examples

• Take for example the Tully-Fisher relation. It relates the luminosity of a spiral galaxy with the 4th power of its rotational velocity. It is a useful heuristic relation, extracted from data, and has predictive power. There is no derivation of that relation; yet I doubt any physicist would argue it is a fundamental law. Instead, with increasing understanding of astrophysical processes, we will finally be able to derive it.
• Stefan came up with an interesting historical example, the Titius-Bode law according to which the distance of planets to the sun grows exponentially with their order in the sequence. The law works pretty well up to Uranus and fails with Neptune, but the far out planets were not known when the law was suggested. People once thought the planets' orbits are fixed by fundamental principles, but with better understanding about the gravitational interaction, the "law" was downgraded to a "rule," or possibly just a coincidence. Though with further knowledge about the dynamics relevant for the formation of solar systems the approximate validity of the relation might be an "emergent" feature one can expect to approximately be valid.
• Then there is of course the often discussed question whether it is in principle possible to derive all of biology, psychology, sociology and economics from physics and thus physics is the most fundamental of all sciences. Many physicists believe this to be the case. For that reason, one of my profs used to refer to physics as “the queen of sciences” (physics is a female noun in German). But we are far away from practically achieving such a derivation, and we thus do not actually know which of the three cases of “cannot be derived” we are dealing with. Already at the level of proteins things get murky, and we should be considering the option that indeed biology might be as fundamental as physics in the sense that it cannot be derived - cannot be derived in principle, not ever.

One of the reasons why the first case might apply even though reductionism has worked so well over a large range of scales is that in some areas of science the separation of scales might no longer work, and/or there might be no scale that can be used for separation. In physics typically the scale is energy, and we are used to neglect things that happen at energies much higher (wavelengths much smaller) than what we are probing. We know this is a safe procedure backed up by the framework of effective field theories. In contrast, a system like our societies does not simply have higher level organizations constituted out of smaller elements, such that these smaller elements define the "emergent" properties. Instead, these organizations also act back on the elements that they are built of and change their behaviour.

Coming back to physics, there are of course the questions that are hotly discussed at the front of research today, those asking what is fundamental in our present theories. Can the masses of particles in the Standard Model be derived from a more fundamental theory? Are space and time themselves emergent from an underlying theory (generally expected to marry quantum mechanics with general relativity). Is quantum mechanics fundamental, or can the quantization procedure and the measurement prescription be derived from a more complete theory?

I don’t know. But I really, really want to know.

Aside: Some weeks ago Clifford also wrote about the question what is fundamental, anyway? Since he sent me the link to make sure I don’t miss it, I can’t get away without mentioning it. Clifford is mostly concerned with people who use the label “more fundamental” to mean their work is more relevant. While that might happen, people using superlatives to claim their own work (life, opinion) is “more this” or “more that” than others’ is hardly remarkable, and certainly not specific to theoretical physics. The other point Clifford makes is that “Nature recycles good ideas,” meaning that the framework of fundamental theories can often also be found to be useful in non-fundamental areas - and the other way 'round. It is an interesting point, but it addresses more the question where one can find inspiration, not what is actually fundamental.

Bottomline

A theory is fundamental if it cannot be derived from a more complete theory, yet there are different reasons for why we may not be able to derive it: It might not be possible in principle, it might not be possible in practice, or we might not yet have the sufficient knowledge to do it. In general, we do not know which case we are dealing with. Misjudgement of the situation can waste a lot of time and hinder progress. If we wrongly believe a property is not fundamental, we risk searching forever for a more fundamental explanation that doesn't exist. On the other hand, if we believe something is fundamental even though it isn't, our understanding of Nature will remain limited. What is sure though is that understanding always starts with a question.

FQXi on the Azores

As previously mentioned, I am currently at the FQXi conference in Ponta Delgada on San Miguel, Azores. Some of you correctly noticed the only purpose of this meeting is to annoy everybody who isn't here. San Miguel is stunningly beautiful, though the weather has been mostly cloudy and rainy. On the other hand, it doesn't hurt so much then to sit in a deep-frozen seminar room. The Azorians seem to live mostly from agriculture and tourism. They have a university, but it's distributed over three islands and focuses on the hands-on fields, engineering, economics, medicine etc.



It has taken me a while to pin down why I find the meeting considerably more interesting than conferences I usually go to. One reason is certainly the variety of topics. Most conferences these days feature a monoculture of specialists in one particular area. And while that is very efficient for exchanging recent results, it also becomes repetitive rather easily. Here, we have a mix of "fundamental" fields, covering cosmology, quantum mechanics, quantum information and quantum gravity. There are also some philosophers here, and one experimentalist. (I think it's by accident rather than design he's the only one.)

But what really stands that the topics discussed are bold. There's Olaf Dreyer speculating on the origin of space and time from matter, Paul Davies on the relevance of increasing complexity in the evolution of the universe and the role of the observer, Anthony Agiurre about false vacuum bubbles, Eduardo Guendelman on the possibiliy to create universes, Fotini Markopoulou on the emergence of space from a non-geometric phase in the early universe, and Louis Crane on black holes as power sources. Depending on your taste, you might call them courageous or nuts. Laura Mersini-Houghton who talked about the possibility of finding evidence for the multiverse through entanglement on super-horizon scales is one of the more conservative here. There is also lot of talk about the arrow of time, alien civilisations, and the Future of Sex.

I also met another blogger many of you will know, Scott Aaronson, who turned out to be younger and more, oohm, entertaining than I thought

[Scott Aaronson]
Then there are the usual suspects, Garrett Lisi, Julian Barbour, Max Tegmark etc. You find the full list of participants here.


[Julian Barbour and Olaf Dreyer]

I further meet Zeeya Merali who wrote the article for New Scientist on Garrett's "Exceptionally Simple Theory of Everything." Zeeya turned out to be a very charming young women with a PhD in physics who finds writing about science a great way to follow her fascination with physics. Over dinner, we had an interesting discussion about science journalism and science blogging.

The multiverse is a recurring issue that people seem to be very divided on, both with respect to existence and interpretation. Interestingly, on the list with questions that were thought to become/remain relevant within the next ten years "Understanding String Theory" ended up having one of the lowest scores. I'm not sure though this reflects more than the interests of the participants.

Yesterday we had a group discussion on what is "fundamental," I will tell you about that some other time.

You find a lot more details on the conference and the talks on the FQXi blog.