Friday, July 30, 2010

Note from Away

[Perimeter Institute has a monthly newsletter (not online). It regularly features pieces from PI alumni, called “Note from Away.” During my last visit at PI, I was asked to write one. Originally meant to appear in the June edition, it will now probably appear next month. Supposed to summarize the changes due to move and new job, I thought it would fit well on my blog as well.]

After three years at PI, last September I moved to Stockholm to start my new position as assistant professor at NORDITA. I don't know why, but upon mentioning my new destination at least five Canadians independently replied with a friendly, “Oh, Switzerland, eh? How exciting.” So just we're on the same page: Stockholm is the capital of Sweden. Switzerland is the little piece of land just below Germany that doesn't want to join the EU because they believe they've invented democracy. Switzerland is cheese and mountains. Sweden is ABBA and the Nobel prize. It's very North and very European. It's as close to the North Pole and as close to socialism as I ever want to get.

NORDITA is “The Nordic Institute for Theoretical Physics” and a very pleasant place to work. It is in many respects similar to PI. Like PI, it is a pure research institute, so there are no teaching duties. We have close ties to the nearby university, in this case the KTH (Royal Technical Highschool Royal Institute of Technology); the physics department is basically next door. NORDITA is also a very interdisciplinary place, so a lot of effort is put into facilitating communication between the different disciplines. The disciplines themselves, however, differ from those represented at PI. Besides particle physics and cosmology, we have astrophysics, condensed matter and biophysics, which makes for a very interesting mix. What I miss from PI, though, are the quantum gravity and the quantum foundation groups.

That's then where the similarities end. NORDITA is a much smaller place than PI. As such, it is more personal, and less burdened with administration and policies. Further, NORDITA doesn't sit on a few hundred million dollars, so our possibilities are much more constrained. Most notably, we don't have a public outreach program, something I have always especially appreciated at PI.

Besides my general interests in cosmology and complex systems, the focus of my research continues to be the exploration of possibilities to find experimental evidence for quantum gravity and to distinguish different models.

I was just organizing a workshop on this topic, the ESQG 2010. Check out the website for more details. The phenomenology of quantum gravity is still a young research field but promises to become even livelier in the future. It is an exciting area to work in, and I especially like that it combines many different areas of both theoretical and experimental physics.

As for Stockholm itself, it's clean, it's green, it's well-organized, interesting, and at least in the summer stunningly beautiful. Crown Princess Victoria just got married, and following “Midsommarafton” (midsummer's eve) the whole country is now on vacation. I think of you guys every time I hear ABBA's “Waterloo” on the radio, i.e. about once every hour.

As most of you know, you can follow me on my blog Backreaction, which I write together with my husband, Stefan.
Ha det så bra,


[A week after I wrote the above, the driver who brought me to the airport put my bags into the trunk and said: “You now live in Switzerland, eh?”]

Monday, July 26, 2010

Detection of Dark Energy on Earth? - Improbable

I recently came across this paper
    Exploring the possibility of detecting dark energy in a terrestrial experiment using atom interferometry
    By Martin L. Perl and Holger Mueller
    arXiv:1001.4061v1 [physics.ins-det]
The topic sounded interesting, so I read it, and here's my conclusions.


Dark energy is according to today's most widely accepted model for the evolution of the universe the main constituent filling space-time around us. It has the peculiar property that it accelerates the expansion of the universe, a feature that has been confirmed by an increasing number of experiments. In the simplest case, the dark energy component is just constant in time and space and is identical to the Cosmological Constant, commonly denoted Λ. There are however many alternative proposals for dark energy that are not just constant, but so far experimental tests for their specific behavior are lacking.

Due to its peculiar properties, as well as the specific value of its measured density, the existence of dark energy is one of the biggest puzzles in theoretical physics today. While it is easily possible to incorporate it into our models as a source for gravity, its microscopic origin is not understood. For more details, see my post on the Cosmological Constant.

The other puzzle that modern cosmology has given to us is that of dark matter. Dark matter is another constituent of the universe whose existence has been confirmed by many experiments, but it's microscopic origin is still unclear. In contrast to dark energy however, dark matter behaves pretty much like normal matter, the stuff that we are made of. Except that, well, it's dark, meaning it does not or hardly emit any detectable radiation. In other words, we can't see it like we see galaxies on our night sky. The most widely accepted explanation for our observations is that dark matter is made of particles that just happen to couple very weakly to those that we are made of. Many candidates for dark matter particles are presently discussed and experiments for direct detection are under way in different places, though results are inconclusive so far. For more details, see my post on Dark Matter.

Detecting Dark Energy with Atom Interferometry

The idea of Perl and Mueller's proposal is the following. Beams of atoms are brought to interfere after having traveled two different paths. These paths are of the same length, but differ in their location within the Earth's gravitational field such that one beam feels more, the other less, of the gravitational force. With the method of interferometry one can detect even tiny shifts in the phase of the wavelengths of the beam. The phase of the beam does depend on the force exerted on it, which means that the interferometry allows to measure the difference in the gravitational force that the atoms have been subject to on the two paths. These experiments have previously been successfully performed. Note that the experiment is sensitive not only to the gravitational force, but in fact to any force that would act on the particles. For a nice explanation of such experiments, see eg. arXiv:0905.1929v2 [gr-qc].

Perl and Mueller now suggest to use two interferometers, both with the same setup as above, and measure the difference in the phase shift between both. With this one would be able to measure even tiny changes in the gravitational force between the locations of the both interferometers, or any other unknown force acting on the atoms. They have estimated the precision that can be reached with this experiment to be about 10-17 of the gravitational force on the surface of the Earth. That I think is quite remarkable indeed.

What does this have to do with dark energy? In their paper, they suggest that this experiment would be able to detect fluctuations in the dark energy density.

Can this work?

Let us note that in case the dark energy was just a Cosmological Constant, it wouldn't have such fluctuations and thus not be detectable by this method. Nevertheless, if it was possible what Perl and Mueller claim, this would give us a grip on the microscopic origin of dark energy and be quite exciting indeed.

I was puzzled however by two things.

First, it is entirely unclear why the detection method proposed would be sensitive to dark energy in particular. It simply measures tiny fluctuations in the forces on the particles. On the timescales that the authors are interested in, one can pretty much exclude fluctuations due to motion of stellar objects or shifts in the Earth's matter. But it seems more plausible to me that such fluctuations, should they exist, would be caused by drifting clumps of dark matter rather than dark energy. In any case, one wouldn't actually know what the origin was.

Second, and more important, I was very suspicious that atom interferometry would suffice to measure something as dilute as the density of dark energy. Putting in some numbers, I estimated the gravitational force that a cubic meter of dark energy stuff would have at its surface. I was guessing that a cubic meter would be the typical size of the experiment and thus the scale that the density fluctuations should occur on. It turns out that this gravitational force of the dark energy clump would be be 38 orders of magnitude smaller than the gravitational force of the Earth. That's more than 20 orders of magnitude below the precision of the proposed experiment. If one takes clumps of dark matter instead one gains 5 orders of magnitude, but still way off. If one considers larger clumps or overdensities (possibly moving very quickly through the experiment), one can gain some more orders of magnitude, but it becomes increasingly implausible at this point.

So I wrote an email to the authors...

... asking for a clarification. I got a fast and very useful reply from Holger Mueller. He explains that Martin Perl is the creator of the idea, and Mueller is helping out on the experimental site. Mueller agreed on my reservations about the experiment's suitability to detect dark energy:
“You are right that the only way we can detect dark energy (or dark matter) is if it has a nongravitational interaction with ordinary matter that is much stronger than the gravitational one (and the dark energy or dark matter must be inhomogeneous).”
This is because, as previously mentioned, their proposed experiment does not distinguish between the sort of force acting on the atom beams. I do however not know of any sort of dark energy that would have this property needed for detection.

Mueller explained his point of view as follows:
“To me as an experimentalist, it is not my primary concern whether there is a theory suggesting that there should be a signal, but whether our experiment will probe some region of the parameter space wherein signals have not been ruled out by previous experiments.”
And I agree that it is a worthwhile experiment to be done. After all one never knows what one might find! However, and unfortunately as I want to add, it seems extremely implausible to me that this experiment would detect dark energy.

Saturday, July 24, 2010

Physics or Philosophy?

In a recent comment Charles has drawn my attention to an interview with Sheldon Glashow, a "Viewpoint on String Theory." I'm not sure when this interview was conducted, I think it was 2003. In any case I thought it might be of interest for you and it fits well with the theme of our recent workshop on Experimental Search for Quantum Gravity, so I want to use it to discuss some questions about our search for quantum gravity.

Glashow is very critical of string theory and does not hesitate to say so:
"[S]uperstring theory ... is, so far as I can see, totally divorced from experiment or observation. If not totally divorced, pretty well divorced. They will deny that, these string theorists.

[T]here ain't no experiment that could be done nor is there any observation that could be made that would say, "You guys are wrong." The theory is safe, permanently safe. I ask you, is that a theory of physics or a philosophy?

There is today a disconnect in the world of physics. Let me put it bluntly. There are physicists, and there are string theorists."

He is careful to then point out that string theory is not entirely useless, just that its use is unclear:
"[String theory] leads to many interesting ideas... It has had an impact on modern mathematics. They may even have a practical impact some day, these things that string theorists do. One never knows, just as number theory, the most useless of the mathematical sciences, has given us cryptography and has given us a secure way to encode information. The string theorist may also produce something equally useful. May. So it is science, it is physics, it is mathematics. It does stimulate ideas in related fields."
Glashow could, at the time the interview was conducted, not know of the more recent applications of string theory to heavy ion physics or condensed matter systems. Arguably, this is exactly the practical impact that he asks for. He ends on a conciliatory note, speaking of his string theory friends:
"[A]lthough I occasionally pick on the work string theorists do, I describe them as physicists. They are interested in the same problems that I am. They're approaching those problems in different ways, ways that they regard as somewhat more productive than I do. But they're not searching for a theory of everything. They're just trying to create better theories."
Indeed, I would agree that physicists will find different approaches promising, but in the end we're all - more or less - interested in finding solutions to the same problems. The reason why I work on the phenomenology of quantum gravity is not that I think it's the one and only right way to progress, but that it's one of the necessary contributions and one that presently not enough people work on.

In any case, the question that I would like to draw from this interview and pose to you is whether there's a balance between phenomenology and pure theory that is ideal for progress and if so, how that balance can be reached?

To add my two cents: During the last decade or so, maybe starting with string-theory-inspired extra-dimensional models, in the area of physics beyond the standard model one could clearly notice phenomenology come into more fashion. I certainly welcome this trend. The problem is however that many of the phenomenological models we've seen are little more than ad-hoc proposed parameterizations of not-yet-observed effects (and lets not forget that adding parameters typically allows a better fit of the data). It thus seems to me one of the essential factors needed is a healthy interaction between theory, phenomenology, and experiment. A hundred years or so ago, it would have been hard to imagine these areas being disconnected, but the increase of our communities has resulted in a specialization that brings the risk of negatively affecting these vital connections. In the beginning of his interview, Glashow also wonders what happened to this interaction.

It is very easy today to focus on ones' own community and not look right or left. To make matters worse, it might even be career-wise beneficial. One of the side-effects is then that people outside that community may wonder if it's physics or philosophy. This incidentally is nothing specific to string theory, it's just that there's so many string theorists that other people talk about it. I wouldn't be surprised if the same thing happens in other fields than physics as well. (Neuroeconomics - Science or Philosophy?) I'm having one of my more optimistic days today. Thus, I think the trend we've seen in the last years is a good one, and one that will eventually lead to the connection between quantum gravity theory and experiment that we are lacking so far.

Thursday, July 22, 2010

Recent Distractions

Douglas Adams’ Hitchhiker’s Guide to the Galaxy: Part Six of Three
And Another Thing
By Eoin Colfer

This book will probably be totally incomprehensible if you haven't read the other parts of the trilogy. But if you're familiar with Douglas Adam's super-galactic fantasies, you'll meet well-known friends and gain some insights into the Vogonic psychology. The plot is somewhat of a stretch and serves mostly to accommodate the Hitchhiker Guide's explanations of other species and their bizarre habits, but you can be sure to have one or the other good laugh. It makes a nice and entertaining read, but is mostly for fans.

The Secret History
By Donna Tartt

An extremely well written book with carefully worked out characters. Unfortunately, it takes like 150 pages for anything to happen. Then when finally something happens, you already know what will happen. And the second half of the book everybody is walking around, drinking too much, with a bad consciousness about what happened. Since I have no particular interest in Greek grammar or mythology I found some parts of the book quite cumbersome to read. Taken together, I'm all willing to recognize it as a masterfully composed book, but the plot didn't enthrall me.

The Girl with the Dragon Tattoo
By Stieg Larsson

Is an excellent crime story set in Sweden, so I felt it was a must-read for me. The plot has many unexpected twists, new evidence showing up, never gets too obvious, and never gets too implausible. The characters are interesting though they remain a bit flat. The book was converted to a movie (which I didn't see) and has two sequels (which I haven't read). Totally recommendable as a holiday read.

Merde Happens
By Stephen Clarke

Is the kind of book you buy in an airport shop and that's exactly where I bought it. An amusing story about a British guy with a French girlfriend who has to go on a road trip through the USA promoting tourism to his home country. Plays nicely with clichees. Not a particularly deep story and not a plot that makes a lot of sense, but entertaining.

Elchtest: Ein Jahr in Bullerbü
By Gunnar Herrmann

Is the story of a German moving to Stockholm with his wife. The plot can be exhaustively described as they buy a house. I guess you have to be a German who lives or has lived in Sweden to appreciate the book. It's very on spot with the German-Swedish differences. I don't think it comes in an English translation though.

Monday, July 19, 2010

Non-Gaussianities in the CMB

"Non-Gaussianities in the temperature fluctuations of the Cosmic Microwave Background" sounds like a perfect conversation topic to put your date to sleep, but if you have an interest in Cosmology or Quantum Gravity, it's definitely something you should have heard about.

The Cosmic Microwave Background (CMB) is radiation we receive today from a time when the universe was about 300,000 years young. At that time, radiation decoupled from matter and since then, photons could travel almost undisturbed. The CMB shows the temperature, or the inverse wavelength, of the microwaves that we receive on Earth from these early times.

The mean temperature of the CMB is approximately 2.7 Kelvin, and is a blackbody spectrum to truly amazing accuracy. What we will be concerned with here however is not the mean temperature, but tiny fluctuations around this temperature. These carry a lot of information about the conditions in the early universe which can help us understand the origin of the structures that we see today, and the processes that were important in the early universe. These fluctuations are of the order micro-Kelvin, and have been measured by NASA's WMAP mission. You probably have all seen their skymap of the temperature fluctuations:

We have discussed the features and usefulness of the CMB temperature fluctuations a few times already, see e.g. my earlier posts The CMB Power Spectrum and Anomalous Alignments in the CMB.

One way to extract information from the data is to look at correlation functions. These come in integer orders like the two-point function, the three-point function, the four-point function etc. There also is a one-point function but ‒ assuming a homogeneous probability distribution ‒ you already know it: it's just the expectation value. In our case, it would be the mean temperature. The two-point function tells you something about the correlation length in the distribution.

The relevant quantity we are concerned with here is the three-point function. (Confusingly enough the three-point function is also known as bi-spectrum.) To compute it, you roughly take three different points of your distribution, multiply the value of the function (here the temperature), and integrate over combinations of three points. Even from this rough description you can notice two things. First, it's several ugly integrals that are hard to compute, especially with loads of data. Second, multiplying small numbers makes even smaller numbers, thus the result is in risk of dropping below the uncertainties in your measurements. Therefore it's hard to come by this observable, yet it's what one wants to extract from the data because it contains information beyond the simplest (single-field, slow-roll) inflation scenario. This simplest scenario predicts the temperature fluctuations to be to very good precision a Gaussian distribution. If they were exactly Gaussian, the three-point function would vanish, and all higher-order correlations would follow from the two-point function. A non-vanishing three-point function would thus be, here it comes, an indication for the non-Gaussianity of the temperature fluctuations, and an indication for new physics.

There had indeed previously been rumors that non-Gaussianities had been found in an analysis of the CMB data, see e.g. this post on Non-Gaussian CMB over at Resonaances. At that time I heard like half a dozen talks on the topic, yet was reasonably sure the "signal" would vanish back into noise as indeed it did. To our present knowledge, the data with the uncertainty we have is still compatible with a Gaussian spectrum. (One has to be somewhat careful when one reads about these bounds since there's several different ones. That's because the full three-point function is pretty much impossible to calculate. What people have done instead is to take samples of specific threesomes of points, e.g. those forming equilateral triangles, or obtuse angled ones, thus there's different bounds depending on the triangles chosen.)

However, the important thing to note is that the uncertainty in these observations will go down in the soon future, with the WMAP 8 years mission results one expects a 20% improvement on the bounds, while Planck can yield a factor of 4. Now if there was an indication for non-Gaussianity this would be very exciting. Then the question is of course, what is the physics behind that? What I guess is going to happen is that anybody with their model will predict non-Gaussianities. I wouldn't be surprised if suddenly it will be a signature for cosmic strings, evidence for the multiverse and also a prediction of Loop Quantum Cosmology. It will certainly take some while to sort out these things. In any case however, I am sure it is a topic you will hear more about in the coming years.

Friday, July 16, 2010

ESQG 2010 Conference Photo

We just wrapped up our workshop on Experimental Search for Quantum Gravity. It was a tremendously interesting meeting, and well worth the effort of the organization. Though plagued by several problems and technical glitches (beamer not working, speaker sick, wireless not working, building company deciding to replace the windows in the guest apartments) I think we managed it reasonably gracefully and people had fun. The discussions in particular I thought went very well and stimulated a lot of vivid exchange. It will take a week or so for the talks and slides to be uploaded, and at that point I'll write a short summary of my impressions, so stay tuned. For now, here's the conference photo, taken yesterday evening before the BBQ. As you can see, we had brilliant weather, and lots of bright people ;-)

I wish you all a nice weekend!

Monday, July 12, 2010

ESQG 2010 - Finally here!

After almost a year of preparation, today is first day of our workshop on Experimental Search for Quantum Gravity that I've been organizing together with Lee Smolin and Greg Landsberg. I'm looking forward to an exciting week. As you can guess, I'll be quite busy during the workshop and I'm going on vacation the following week, so you might not hear much from me for a while. We'll have all talks and discussions recorded, so they should appear on the website once we've sorted out the upload. I hope it doesn't rain on our BBQ on Thursday!

Friday, July 09, 2010

This and That

  • You might have heard that according to the result of a new measurement the proton is some percent smaller than previously thought. Chad Orzel has an excellent post explaining what this means and doesn't mean.

  • Spiegel Online has an interesting article on Norway's experience with compulsory women quotas on company boards. My experience with compulsory women quotas as been very unconvincing. What happened is exactly what you can read in the article what Norwegians were afraid would happen before the law was introduced in 2004: you were forced to take women who were either unqualified or incompetent or both. Amazingly enough it seems the Norwegian's experience has been mostly positive and, despite the outcries before the introduction of the law, after it became a matter of fact there haven't been complaints about it. I think the relevant difference to the cases I have witnessed is the availability of qualified women in the pool. In the situations I saw, there were simply way to many (we're talking a factor 10 below the quota that had to be achieved). As it seems from the article, Norwegian companies however had no problems finding qualified female board members. In any case, this outcome was unexpected to me and gave me something to think about.

  • The Globe and Mail reports on a forum banning anonymity and forcing users to use real names instead. That in itself isn't so interesting, more interesting is that they dubbed it "the latest sign that online anonymity is falling out of favour with many companies." I'm not at all sure it's really necessary to force people to use their real names, I think pseudonymes will do as well as long as they have a value for the user, but I am happy to hear that the anonymity disease on the internet seems to have been recognized for what it is: sickening. I'm thus wondering what change we'll see coming in the soon future.

Wednesday, July 07, 2010

In Praise of Black Holes

First time I came to work on black holes was a funny story. I went to one of the senior profs at the institute asking for a topic for my master's thesis. The focus area of the institute was heavy ion and nuclear physics, so the prof suggested two topics from this field. Since I wasn't too excited about that, he added a third that was to show that black holes can't exist by working out an argument that he briefly sketched. Faced with that selection, I went away with the task of showing black holes can't exist.

I was an undergraduate at that time, I had a bachelor's degree in math, not physics, and knew next to nothing about black holes and quantum effects in their vicinity. Still, it didn't take me more than 3 weeks to figure out that his idea wouldn't work for what I thought were quite obvious reasons. I went to some other prof asking for advice, upon which I learned that the topic had previously been given to two other students who, unfortunate for the prof, came to the same conclusion as I. I was then luckily handed over to a very bright postdoc who worked in astrophysics with whom I deviated the topic to one in which we could arrive at results and not start with the result.

Knowing what we know today, the topic suggested might seem odd to you. However, one has to see this in historical context. This anecdote happened in the mid 90s and by then it had been discussed for decades whether black holes are merely mathematically possible solutions of Einstein's theory of General Relativity, or if they are physical reality. It was only in the mid to late 90s that observational evidence became accurate enough to convince most scientists of the existence of black holes. At this time, evidence meant that a black hole is the most straightforward and most plausible, minimalistic, and generally accepted explanation of the data. As I recall one seminar speaker saying: If it looks like a duck and quacks like a duck, then it probably is a black hole. Though I might have garbled that up. The senior prof's argument against their existence was that god would not disconnect himself from part of his universe. Can't make that stuff up.

In any case, for some while there have been more or less artificial alternative explanations around for super-compact objects that resemble black holes but have no horizon. These alternative solutions typically are very implausible on the theoretical side. In addition, since a few years we also have experimental evidence that allows us to distinguish a solid surface from a horizon, see earlier post on Evidence for the Black Hole Horizon. So that duck clearly is a black hole. If you need any more evidence for the existence of black holes: they've made it into pop music. Muse, Supermassive Black Hole. Love that song, sorry, urgent need to embed:


Oohm, back to the physics, let me be very clear here: a black hole is characterized by its horizon, not by its quack. The full solution of Einstein's field equations does not only have a horizon, it also has a singularity at the center of the black hole. First thing to note is that we can't see the singularity because it's surrounded by the horizon and thus hidden from all observational efforts. (That's known as Cosmic Censorship.) Maybe more important, close by the singularity we come into a regime of very strong curvature and it is doubtful that General Relativity is still the correct theory to apply. Close by the singularity, quantum effects of gravity should become important. We do not yet know what the right theory is, but the correct solution in this regime looks probably nothing like the classical solution.

If a singularity appears in your theory, it usually means you've used your theory out of its range of applicability. A nice example for that are singularities that appear in hydrodynamics. Stefan wrote about this in his post Singularities in your Kitchen. Needless to say, these singularities are an artifact of still using a theory on scales where instead a more precise theory of the microscopic structure of the fluid would have become relevant. Most people working on quantum gravity believe that the singularity in the black hole solution is a similar artifact of applying a theory out of its range of applicability.

What is so fascinating about black holes is how many different areas of physics they combine. There is, first of all, of course the astrophysical aspects, both in experiment and theory. These differ greatly between supermassive black holes (like at the center of galaxies) and stellar black holes (formed from collapse of stars). An interesting topic is also the transition from the latter to the former. There's further so-called 'primordial black holes,' that might have been formed from density fluctuations in the early universe. These are usually thought to be of much smaller mass than stellar black holes. These primordial black holes come back every now and then as dark matter candidates or as explanation for gamma ray sources etc, but so far none of the models, both for their formation and signature, has been really convincing. And then there's the quantum black holes that might be possible to produce in colliders in scenarios where the Planck scale is lowered; for more details see my post on Micro Black Holes.

Since black holes inevitably imply the existence of regimes where quantum gravitational effects are relevant, it is not surprising that they have received a lot of attention in the quantum gravity community. The study of black holes has thus lead us to discover and explore the relation between General Relativity and thermodynamics, a topic that's been going strong since almost 30 years now and most recently resulted in Erik Verlinde's claim that General Relativity actually is thermodynamics. Black hole physics has given rise to 't Hooft's conjecture of the Holographic Principle, probably one of the most surprising and also intriguing thoughts that physics has heard of since Einstein, and a thought that has spurred a rather dramatic amount of research. A lot of this research has been dedicated to find a solution to the Black Hole Information Loss Problem. The need to connect black hole physics (both emission and accretion) to the standard model further brings in particle physics and there are also interesting analogies between black holes and some condensed matter systems. You can find a nice review of the latter in Ralf Schützhold's recent paper Emergent Horizons in the Laboratory.

The workshop on black holes that I was attending 2 weeks ago in Bonn covered a good part of these topics, though the astrophysics was clearly dominant and other aspects like holography were entirely missing. In any case, it reminded me of my initial fascination with the topic. If you are a student, I can warmly recommend to work on a topic related to black hole physics because it gives you the opportunity to learn about a broad range of interesting concepts.

Tuesday, July 06, 2010

Blogger Bug

Hi All,

There's something seriously wrong with Blogger's comment feature. The problem is not restricted to this blog and has already been reported by many others on the help pages. As you will notice, the recent comments features doesn't work, and in fact new comments don't appear - including my own. There is nothing I can do about it. I do receive your submitted comments by email, but I don't know when they will appear. I'll let you know when the problem has been resolved.

PS: Here is the forum thread where you can report your problem.

Update, July 6, 6:20 pm CET: Comments seem to be working again... At least partly. The comment count still doesn't work.

Update, July 7, 7:00 am CET: All is working again.

Sunday, July 04, 2010


When I was a teenager, in the library I once came across a book on curses, spells and magical potions. Since I was just in a phase of reading fantasy literature, I could not resist having a look. It was full with recipes and rituals for all sorts of purposes. Most of them were love spells. I didn't really have a lot of use for that then. The one I recall best was against migraine. The cure was to press a raw egg against your forehead and mumble a few magical words that would make the pain go into the egg. The pain would then be passed on to whoever was unlucky enough to eat the egg.

I was fascinated by the amount of detail that was paid to these magical procedures, like at which time of the day and which moon phase herbs were supposed to be cut, and I liked to imagine what the world would be like if these spells actually worked. I didn't try any of them. My reasoning was if they would actually work, certainly nobody on this planet would still suffer from a broken heart or headache. Today I would probably give a different reason. The one offering a miracle cure is the one who should come up with a scientific documentation for the efficiency of their treatment. Needless to say, the spell book didn't bother with evidence that the rituals had any effect whatsoever.

I was thinking about the little book with the spells recently when I coincidentally came across a website selling spells. Sure, I know the internet is cluttered with nonsense, but for whatever reason this made me think. It's not only that the site offered "love spells, magic spells, reunion love spells, lover return spells, magical things, attraction love spells" and so on, they actually want money for it. "I have made magic spells, charms, genies, talismans and amulets available to you as a world renowned GURU and not as an amateur player in this field." Beware those capitals. The "lover return spells" seem to be particularly widespread. For what I am concerned, the sudden return of my past lovers would probably rapidly turn into a nightmare. So, maybe better, you might want to get a grip on a genie:
"The Conjuration or Invocation of genies are now possible bye following precisely the genie invocation spells and certian powerful invocation rituals prepared by me[...] A few examples of the things that these powerful genie spirits can do for you [...] If you desire to travel to another country, you don't need any documents or aircraft. You just order your genie and it will hold your hands and in a fraction of a minute, you will be in the land of your dreams."

Maybe he's just selling sleeping pills? But no, the genie can also "give you the correct winning numbers for LOTTO, POOLS, BINGO etc." Makes one wonder why the GURU hasn't won the lottery yet.

Okay, I admit, I didn't come across the website coincidentally. I read some forum where a woman insisted a spell she recently bought for only $200 had helped her (with a health problem). It was not an advert (no link, no name attached). I actually didn't know what she was talking about at first. After I figured she spent $200 on somebody sending her an email with some probably random generated "magical words" I could not but be stunned. It raised two questions for me: First, why do people waste money on entirely useless crap? Second, doesn't standard economical theory tells us that the value of a product reflects all the information about it? So why then doesn't the miracle of the free market accurately price useless spells at zero? (To be fair, they probably have some slight entertainment value and a psychological effect. But that's like saying you'd spend $200 on an iPod, and if it doesn't work the money was still well spent on making you feel better for helping the economy.)

Magical thinking

Wikipedia offers the following definition for magical thinking:
"[T]he term magical thinking is used to describe causal reasoning that looks for correlation between acts or utterances and certain events."

However, just looking for correlations could as well be scientific thinking. It is more helpful if one adds that the anthropologist E. Tylor characterized such thinking as "pre-logical." Basically, pretty much by definition, magic is non-scientific. Magical thinking believes in causal relations or correlations where there are none. You believe in magic if you really think pressing a raw egg against your head sucks up the pain. But of course the boundary between magic and science becomes blurry when one reaches the front of research. A relation might after all exist, just that science hasn't yet looked at it. In fact, the smarter sellers of useless crap don't just insist on nonscientific products which amounts to declaring there's no known use of them. They add pseudoscientific explanations in the hope one or the other reader will be impressed.

An example of such unashamed pseudoscience are "Takionic products," that "with their aligned atomic polarities, enhance the body's natural ability to draw from the Tachyon Field for its energy needs." We can read for example on this website that
"Since existence of a Tachyon Universe cannot be proven by instrumentation currently available, Tachyon theory is constructed by examining observable effects and drawing conclusions. Since Tachyon theory blurs the distinction between metaphysics (which deals with non-physical realities) and physics (which deals with physical realities), it has not been well-received by some main-stream physicists [...] Though discredited by some physicists today, Tachyon theory persists, an artifact of theoretical physics that has yet to be replaced by a fully coherent and integrated alternative [...]

We experience the Tachyon Field with our senses, mind and spirit as a warm, pleasurable, energizing and healing sensation. Healers have learned to access the Tachyon Field's resources for its healing powers more successfully than the average person has. Belief in a "Higher Power" enables them to draw upon the Tachyon Field. The more they draw upon it, the more effective as healers they become."

It almost hurts my brain to read this (hand me the egg please). The statement that the "theory" has not been well received by "main-stream physicists" and is "discredited" should be an immediate warning for the reader. It means in plain text no credible scientist believes in this nonsense. Tachyons have been looked for and not been found. There's zero evidence they exist. And even if, they certainly would not do any energizing of your senses by means of a "takionic headband". Needless to say, the website doesn't offer any documentation of the alleged examination of observable effects.

In one of my first years at the Institute for theoretical Physics in Frankfurt, my office mate came across a very similar website selling tachyonic water. They had a service hotline, so he called them. We actually wanted to ask how they believe they can capture tachyons in water. A woman picked up and after a friendly opening, my officemate asked her what a tachyon is. She said she'd have to connect him to the technical service hotline, punched a button and then the line was dead. So much about the scientific details.

Just dumb?

It is easy to dismiss people who fall for pseudoscience like spells, plain water with a fancy name, or genies as dumb. Yet I don't think that's a good explanation.

One of my relatives, when she reached her mid 80s, became quite suspicious of all modern technology. One instance that I recall particularly well is that she had heard or read somewhere that the suddenly omnipresent cellphones' signals are basically radiation that's around us all the time. She then went on to blame it on these electromagnetic waves if a towel dropped off the hook, or something rolled off the table, or she just wasn't able to find it anymore. A perfect example of making up a correlation. I made one or the other attempt to explain that no way the low power in the radiation used could move macroscopic objects, but I had to notice my explanation was pretty much pointless.

It was not that my relative was stupid. In fact, she was even in her high age far from stupid. The problem was that she had no clue how modern technology works and all the basics were missing. The gap had gotten too large. I would have had to start all the way back with Maxwell's equations over a transistor to electromagnetic waves and antennas, microwaves, maybe moving on to the laser that's now a standard ingredient to so many household products. And if you were 86, would you listen to a twenty-something telling you how the world works?

Arthur Clarke's Third Law

"Any sufficiently advanced technology is indistinguishable from magic."

This quotation makes its point very well, though it's a little bit careless. I would want to add that technology can always be distinguished from magic, it's just that the technology might not be possible to understand with the knowledge or means at your disposal. But consider you came across an alien technology for cancer treatment. You might not be able to figure out how it works, but you'd be able to demonstrate that it works. I wouldn't call it magic if you can demonstrate, though maybe not explain, an effect. Indeed, the working of a lot of medications that are in common use today is not well understood. What we do is simply demonstrate that they work to the patients' benefits. Nothing magic about that.

Taken together, I've come to think there's two reasons people fall for magic (non-science) or pseudoscience (wrong science): One is that they have no idea how science works. Making up praises from satisfied customers on a website doesn't amount to evidence. ("Athletes have written letters which claim pain from sport injuries was lessened or eliminated, and rapid recovery obtained, from using Takionic products." Okay, fine. Double blind clinical trial? Just asking.) Second is that they don't have enough information, to be able to tell whether a product has any sensible reason to actually work at the present status of scientific knowledge. See, I have a lot of fantasy, and I can imagine that some thousand years into the future you can download a cure for migraine that consists of a software that lets some device in your computer emit targeted electromagnetic stimuli for affected brain regions that demonstrably alleviate the pain. Not so much different from buying a spell online. Except that that today's scientific knowledge isn't remotely close to making this possible. But to be able to tell, you need to have some rough idea of what the status of science is.

In the end, what it comes down to is lacking eduction. Education both about how science works, and what established scientific knowledge is.

I still haven't figured out though how the non-zero value of useless products fits into general equilibrium theory.

PS: If you get migraine after your breakfast egg, don't blame your wife ;-)

Saturday, July 03, 2010


I've won a vuvuzela! During the Soccer World Cup, our local grocery chain is running a lottery where one gets scratchcards for shopping. On one of the cards, I've scratched off exactly four vuvuzela icons, meaning I now own this wonderful plastic horn, just in time for this afternoon's quarter finals of Germany vs. Argentina.

It neatly comes in the German colours, and with all necessary assembly and safety instructions (120 dB or so in front of the horn can be dangerous...)

As this is a physics blog, you may expect me to say something about the physics of the vuvuzela, but it is too hot today, and I have to prepare for the match.

Besides, there are already great blog posts on the vuvuzela, for example at
Science 2.0, where it is explained that all horns work the same way. You blow into them and that creates a vibrating column of air but the construction of the horn means certain resonant frequencies will occur, or at A quantum of knowledge. And the New Scientist has a nice interview with Trevor Cox, president of the UK Institute of Acoustics, on the sound of the vuvuzela.

And if you'd like to dig really deeply into the science of the instrument, you may try to find a copy of Fletcher and Rossing's Physics of Mucsical Instruments and have a look at the chapters on Pipes, Horns and Cavities, Sound Generation by Reed and Lip Vibrations, and Lip-Drive Brass Instruments.

Have a great weekend!