Getting cuter by the day...

If you've been wondering what age babies are the cutest, there's a scientific answer to that. Yes, there is. In the year 1979, Katherine A. Hildebrandt and Hiram E. Fitzgerald from the Department of Psychology at Michigan State University published the results of their study on "Adults' Perceptions of Infant Sex and Cuteness."

A totally representative group of about 200 American college students of child psychology were shown 60 chromatic photographs of infant faces: 5 male and 5 female each for six age levels (3, 5, 7, 9, 11, and 13 months). The babies were photographed by a professional photographer under controlled conditions when their facial expressions were judged to be relatively neutral, and the infants' shoulders were covered with a gray cape to hide clothing.

The study participants were instructed to rate the photos on a 5-point scale of cuteness (1: not very cute, 2: less cute than average, 3: average cuteness, 4: more cute than average, 5: very cute). The average rating was 2.75, ie somewhat less than averagely cute. The authors write that it's probably the selection of photos with neutral facial expressions and the grey cape which accounted for the students' overall perception as slightly less cute than average. And here's the plot of the results:
So, female cuteness peaks at 9 months.

For the above rating the participants were not told the gender of the child, but asked to guess it, which provided a 'perceived gender' assignment to each photo. In a second experiment, the participants were told a gender which however was randomly picked. It turned out that an infant perceived to be male but labeled female was perceived to be less cute than if it was labeled male. Thus the authors conclude that cuter infants are more likely to be perceived as female, and cuteness expectations are higher on females.

Partly related, Gloria just woke up:

Why do we live in 3+1 dimensions? Another attempt.

It's been a while since we discussed the question why we experience no more and no less than 3 spatial dimensions. The last occasion was a paper by Karch and Randall who tried to shed some light on the issue, if not very convincingly. Now there's a new attempt on the arXiv:

Spacetime Dimensionality from de Sitter Entropy
By Arshad Momen and Rakibur Rahman
arXiv: 1106.4548 [hep-th]

We argue that the spontaneous creation of de Sitter universes favors three spatial dimensions. The conclusion relies on the causal-patch description of de Sitter space, where fiducial observers experience local thermal equilibrium up to a stretched horizon, on the holographic principle, and on some assumptions about the nature of gravity and the constituents of Hawking/Unruh radiation.

What they've done is to calculate the entropy and energy of the Unruh radiation in a causal patch of any one observer in a de Sitter spacetime with d spatial dimensions. Holding the energy fixed and making certain assumptions about the degrees of freedom of the particles in the radiation, the entropy has a local maxium at d= 2.97 spacelike dimensions, a minimum around 7 and goes to infinity for large d. Since the authors restrict themselves to d less or equal to 10, this seems to say for a given amount of energy the entropy is maximal for 3 spacelike dimensions. Assuming that the universe is created by quantum tunneling, the probability for creation is larger the larger the entropy, thus it would be likely then that we live in a space with 3 dimensions.

To calculate the entropy one needs a cutoff the value of which is fixed by matching it to the entropy associated with the de Sitter horizon, so that's where the holographic principle becomes important.

Not only is it crucial that they add an upper bound on the number of dimensions by some other argument, their counting also depends on the number of particles and the dimensions they can propagate into. They are assuming only massless particles contribute, and these are photons and gravitons. Massive particles even with small masses, the authors write, are "unacceptable" because then the cutoff could be sensitive to the Hubble parameter. By considering only photons and gravitons as massless particles they are assuming the standard model. So even in the best case one could say they have a correlation between the number of dimensions and the particle content. Also, in braneworld models the total number of spatial dimensions isn't necessarily the one determining degrees of freedom at low energy; a possibility the authors explicitly say they're not considering.

Thus, as much as I'd like to see a good answer to the question, I'm not very convinced by this one either.

This and That

Some random things that caught my attention recently:

• If you like PhD comics, they're working on a movie: Trailer here.


• The Helmholtz-Zentrum Dresden-Rossendorf set a new world record for magnetic fields with 91.4 teslas.


• You have 1 week left to work out some detail of the 100 year spaceship and send in an abstract for the public symposium Sep 30 - Oct 2nd in Orlando "intended to seed creative energy to “kick-start” the long term research goals." It's for sentences like this that you hire PR people.


• Partly related, I learned the other day from SciAm that the new buzzword after "synergy" and "horizontal integration" is now "convergence." So let's converge on something then.


• Also, the new-name creationists have switched from iIng everything from iKnow to iDontcare and are now replacing spaces with dots, following the ICANN's decision to allow customizable URL suffixes. Ironically though, Google seems to replace the dot with a space if you search for a tag. Anyway, I see huge potential for the arXiv. No more SUSY or MSSM, it's now mond.4u and beyond.higgs. Leave your physics-themed suggestions in the comments!


• Something to look at: Camouflage art.


• And something else to look at: Dear Photograph


• If you like the comic series Asterix and Obelix, you'll love this Study of traumatic brain injuries. To quote from the conclusions "Roman nationality, hypoglossal paresis, lost helmet, and ingestion of the magic potion were significantly correlated with severe initial impairment of consciousness (p ≤ 0.05)."

Interna

So we're back in Germany. For the next months, I'm on parental leave again and Stefan works 9 to 5. Lara and Gloria are now almost 6 months old. They can now both roll over from back to belly, though not the other way round, and they've discovered their feet which make good toys that don't fall out of reach. They can grab and hold things, give them from one hand to the other, and bang them not only in their own but also in other people's faces. They can meanwhile eat quite well from a spoon, though they try to grab the spoon which makes feeding inevitably a mess.

Lara entertains us with a large variety of funny sounds ranging from moo-moo over uee-wee to fffff. The latter is particularly amusing when executed with a mouth full of mashed carrots. Gloria too finds distraction in her 5 minutes older sister and often turns to look at her or rolls into her direction. If Lara burps, Gloria laughs. Lara's hair finally seems to start growing, and it turns out to be lighter than it was at birth. Her eye color on the other hand is turning more brownish by the day. Gloria is still blue eyed and has a hint of blond hair.



Yes, my life has become very pink.

The girls now sleep reasonably well at night, but are more demanding during the day. Lara in particular manages to move around without actually being able to crawl and then gets stuck in all sorts of impossible positions. Gloria apparently loves to chew on cables, and it's good she doesn't have teeth yet. In the coming weeks, we'll have to childproof the apartment.

I have, to my great delight, meanwhile received parental benefits from the Swedish Försäkringskassan, at least for a couple of months, after I managed to convincingly explain I'm indeed still insured with them. The problem seems to have been caused by some EU agreement that assigns me to a German health insurance during my stay here. On the Swedish side however the health and social insurance are both in the domain of the same institution, so they seem to have concluded I'm back in Germany for good, never mind that I'm paying taxes in Sweden. Now they have some difficultly figuring out how many days I'm eligible for since Stefan doesn't live in Sweden. The Germans on the other hand have so far refused to pay a single cent of Stefan's benefits since they don't know what the Swedes will pay for me. The bottomline is we're still sitting on piles of paperwork and money is short. We've also learned of several people who've had similar difficulties which is both comforting and frustrating.

Our Saab's oil leak caused us some more headache than anticipated. Here in Germany we were told the broken part, some rusty hose, would have to be shipped from Sweden. Since we were on the way to Sweden anyway, we contacted some repair place there after arrival just to be told that Saab has only one warehouse for spare parts left, which is in Nyköping, and the part we need is out of stock. They could put in an order for fourhundredsomething Euro, and it might come in anything between next month or never. The car making more insulted noises by the day, I had the great idea to Google for 'Saab spare parts' in Swedish. Two days later I picked the part up from the post office; it came to about 25 Euro. To my amazement, it was indeed the right part and it's being replaced right now. Lesson learned: If you need a spare part for your car, buy it online yourself and bring it to your dealer.

Weather here in Germany is brilliant, 36 Grad, Es wird immer heisser, Es ist Sommer! and the women's soccer world cup has just begun.

No I wont agree to disagree

In a recent NYT article, I learned about the "argumentative theory of reasoning," suggested by Dan Sperber, a French social and cognitive scientist, who is director of the International Cognition and Culture Institute. The essence of his theory seems to be that the evolutionary purpose of argumentation is to win an argument. That, apparently, is a groundbreaking hypothesis as his colleagues mostly argue that the purpose of reasoning is to find the truth, leaving them puzzled why the human brain works so inefficiently to that end. Sperber's postdoc Hugo Mercier has a website that lists the predictions of this theory, most of which are actually postdictions.

I think they've forgotten to disentangle argumentation by subject. There's arguably arguments that for the sake of natural selection you're better off finding out the truth. You can convince me all you want that drinking distilled water will cleanse your soul, you're not going to reproduce 6 feet under. But if the argument is about getting your way (what's for dinner?) then you might indeed be better off packing on arguments in your favor and leaving out those that contradict you. The problem is of course that it's difficult to switch from one mode of argumentation to the other. That's why it's beneficial if scientists have some formal training in which they learn, if not actually the names of well-known cognitive biases, so at least procedures that have proven efficient in avoiding pitfalls of human cognition, cognition that has evolved for other purposes than, say, finding evidence for dark matter.

In any case, this reminded me of a little book I once saw on a bargain bin, "50 ways to stall a discussion." ("50 Arten, sich quer zu stellen" by Frans Krips, you can download it here.) If you ever sat in the 5th installment of yet another seemingly endless committee meeting, consider that everybody else read the book and took the advice very seriously. Here's a sample from the 50 ways:

1. This was not sufficiently discussed
2. We don't have enough information
3. We should first find out how the matter has been dealt with elsewhere
4. This is much too fast
5. Deficient use of language
6. Inadequate standard
7. We first have to discuss some other problem
8. There are other problems of higher societal relevance
9. One just can't do it this way
10. You can't expect that from the people
11. We've discarded so many plans, who cares if we discard yet another
12. We tried this already in 1976
13. We haven't yet assessed the impact of our last decision
14. Who exactly is responsible?
15. We should contact an expert
16. We have to set priorities straight
17. We need a committee on this aspect

And then there is of course the Web2.0 deadlock: we have to agree to disagree. It too fails to differentiate between seeking for truth and seeking for compromise. We can agree to disagree on all matters of taste: Pizza or Sushi? Pink or blue? NIN or RHCP? but when it comes to science, disagreement means one of us is wrong. Finding the right answer is what science is all about. So it's Pizza tonight, dammit.

[Img Src: Very Demotivational]

Exploring Self-perception: Zakaryah Abdulkarim

[Last month, I volunteered for a study at the department of neuroscience at Karolinska Institute, if just out of curiosity to see the place. Eventually it didn't work out with my participation, but I got to meet Zakaryah, a student at the Institute, who kindly agreed to tell us a little about his work there. I certainly learned some new vocabulary. Enjoy!]

I read that you are looking for volunteers for a project. Can you tell us what this is all about?

Yes. The project that I am currently involved in is one in the field of cognitive neuroscience. It is part of the research conducted in the lab of Dr. Henrik Ehrsson at the Department of neuroscience, Karolinska Institute. In this project we use an established perceptual illusion called ‘the body swap illusion’ (Petkova & Ehrsson, 2008) in which healthy participants experience the body of a shop mannequin as their own body to understand the behavioral and neural mechanisms underlying the self-attribution of a whole body to oneself. In particular, we are interested in understanding the neural mechanisms underlying the unitary experience of owning an entire body rather than a set of fragmented body parts. My project will contribute important behavioral and physiological data in support of a neuroimaging study conducted by my direct supervisor PhD-candidate Valeria Petkova.

In my experiment the participants wear head-mounted virtual reality displays, through which they see the mannequin’s body. They then receive simultaneous visual and tactile stimulations of various body parts and fill out a questionnaire regarding their experience. Alternatively they might see a knife approaching the mannequin, in which case the sweating of their palms, the so called galvanic skin response, which is a measurement of the sympathetic nervous systems response to dangerous stimuli is measured via electrodes attached to the fingers of the participant. Since the knife is approaching the mannequin and not the body of the participant, the sweating of the palm is used as an objective measurement of the perception of the body ownership illusion.

What is that sort of research good for?

Understanding the perceptual and neural mechanism involved in how we perceive our own body might be useful in the development of neuroprosthetics. Further, understanding the mechanism underlying the healthy perception of body ownership can help develop diagnostic and therapeutic tools in the treatment of pathological disturbances of the bodily self perception in different groups of patients (i.e. stroke, paraplegia, schizophrenia, anorexia etc.). Finally, the results of this type of research are beneficial for some industrial applications, for example in the field of virtual reality, telerobotics or telepresence.

What future studies would you like to do?

I would probably want to investigate more exactly which areas of the brain are involved in producing this feeling of body ownership and various ways to manipulate this. In particular, it would be interesting to see if one could affect this illusion pharmacologically, and how the illusion is correlated to the features of the subjects, because interestingly, not everyone experience this illusion.

What are the presently most pressing open questions in the field?

Here are some examples:

- What are the exact characteristics (i.e. type, receptive field etc) of the neuronal population involved in the neural computation of body ownership?

-What is the exact role of each node in the neural network indentified to be associated with the sense of owning a body. With other words what is the specific role of the ventral premotor cortex, the intraparietal cortex, the putamen, and the cerebellum?

- What is the interplay between body ownership and the sense of agency in the mechanism of self-awareness?

Do you see any relevance for physics or a role for physicists in that kind of research? If so, what?

Of course! Aside from all the technical equipment that is needed to perform these studies, e.g. MRI-scanners, galvanic skin electrodes etc., this research brings up a lot of fundamental questions about how we perceive ourselves and our surroundings, how we make decisions, how effects on different scales interplay, and I believe physics can contribute a lot to those discussions.

For somebody interested in this research, what further reading can you recommend?

One could read some scientific articles about it, however those can be hard to understand if you do not have a background in medicine or neuroscience. I would recommend those who are interested to read bookchapters about this kind of research, which exist in most of the new books in cognitive neuroscience, for example this.

If I'm in Stockholm and interested volunteering for your or similar research, how do I get in contact?

If you are in Stockholm and interested in participating, the best thing to do would probably be to send me an email, my email-adress is: zakaryah.abdulkarim[at]stud.ki.se. The requirements differ depending on the study, but usually there is some experiment in our lab that one can participate in.

---

Zakaryah is a medical student at Karolinska Institute. In his free time, when he isn’t at Alba Nova taking some evening course that is, he likes exercising, hanging out with friends, and enjoying what the vegetarian cuisine has to offer.

Nonlocal correlations between the Canary Islands

Bell's inequality is the itch on the back of all believers in hidden variables. Based on only a few assumptions it states that some correlations in quantum mechanics can not be achieved by local realistic hidden variables theories. The correlations in hidden variables theories of that type have to fulfill an inequality, now named after John Bell, violations of which have been observed in experiment, thus hidden variables don't describe reality. But as always, the devil is in the details, and if one doesn't pay attention to the details, loopholes remain. For Bell's inequality, there are actually quite a few of them, and to date no experiment has managed to close them all.

The typical experiment for Bell's theorem makes use of a pair of photons (electrons), entangled in polarization (spin). The two particles are send in different directions and their polarizations are measured along different directions. The correlation among the pairs of repeated measurements is subject to Bell's inequality. (Or the more general CHSH inequality).

The maybe most obvious loophole, called the locality loophole, is that information could be locally communicated from one measurement to the other. Since information can maximally be transmitted by the speed of light this is the case if, for example, the second measurement is made with delay to the first, such that the second measurement is in the forward lightcone of the first. Another loophole is that the detector settings may possibly be correlated with the prepared state without any violations of locality if they are in the forward lightcone of the preparation. Since in this case the experimenter cannot actually set the detector as he wishes, it's called the freedom-of-choice loophole.

A case where both loopholes are present is depicted in the space-time image below. The event marked with "E" is the emission of the photos. The red lines are the worldlines of the entangled electrons or photons (in an optical fiber). "A" and "B" are the two measurements and "a" and "b" are the events at which the detector settings are chosen. Also in the image are the forward lightcones of the event "E" and "A".


So that's how you don't want to make your experiment if you're aiming to disprove locally realistic hidden variables. Instead, what you want to do is an experiment as in the second figure below, where not only the measurement events "A" and "B" are spacelike to each other (ie they are not in each other's lightcone), but also the events "a" and "b" at which the detector settings are chosen are spacelike to each other and to the emission of the photons.

Let us also recall that the lightcone is invariant under Lorentz-transformations and thus the statement whether two events are spacelike, timelike or lightlike to each other does not depend on the reference frame. If you manage to do it in one frame, it's good for all frames.

Looks simple enough in a diagram, less simple to actually do it: Entanglement is a fragile state and the speed of light, which is the maximum speed by which (hidden) information might travel is really, really fast. It helps if you let the entangled particles travel over long distances before you make the measurement, but then you have to be very careful in getting the timing right.

And that's exactly what a group of experimentalists around Anton Zeiliger did and published in November in their paper "Violation of local realism with freedom of choice" (arXiv version here). They closed for the first time both of the two above mentioned loopholes by choosing a setting that disabled communication between the measurement events as well as between the preparation of the photons and the choice of detector settings. The test was performed between two Canary Islands, La Palma and Tenerife.


[Image Source: Lonely Planet]
The polarization-entangled pairs of photons were produced in La Palma. One was guided to a transmitter telescope and sent over a distance of 144 km to Tenerife, where it was received by another telescope. The other photon made 6km of circles in a coiled optical fibre in La Palma. The detector settings in La Palma were chosen by a quantum random number generator 1.2 km away from the source, and in Tenerife by another similar but independent random number generator. The measurements violated Bell's inequality by more than 16 standard deviations.

What a beautiful experiment!

But if you're a believer in local realistic hidden variable theories, let me scratch your itch. You can't close the freedom-of-choice loophole in superdeterministic hidden variables theories with this method because there's no true randomness in that case. It doesn't matter where you locate your "random" generator, its outcome was determined arbitrarily long ago in the backward lightcone of the emission.

New Painting

Okay, it's not really new. I actually started it last fall, but only finished this week. It's called "Herbstschatten" (Shadow of fall). Click to enlarge.

Extra Dimensions at the LHC: Status Update

The Planck scale is the scale at which quantum gravitational effects are expected to become important. An extrapolation of the strength of gravity gives a value of 10¹⁶TeV, which is far out of reach for collider experiments. In the late 90s however, it was pointed out by Arkani-Hamed, Dimopoulous and Dvali, that this extrapolation does not hold if our spacetime has additional spacelike dimensions with certain properties. If that was the case, the true Planck scale could actually be at a TeV, an idea that is appealing because it does away with the question why the Planck scale is so large, respectively why gravity is so weak, to begin with. The answer would be, well, it isn't, it is only apparently so: Our naive extrapolation doesn't hold because space-time isn't four-dimensional. (For more details, read my earlier post.)

This (and other) extra dimensional models with a lowered Planck scale have been very popular at the beginning of the last decade and caused an extraordinarily high paper production which reflects not only the number of theoretical particle physicists, but also their desperation to put their skills to work. The most thoroughly analysed consequence of such models are the modification of standard model cross-sections through virtual graviton exchange and the production of black holes at the LHC. The latter possibility in particular received a lot of attention in the media due to some folks who accused physicists of planning the end of the world just to increase their citation count. (For more details, read these earlier posts.)

In any case, the LHC is running now, data is coming in and models are being sorted out, so what's the status?

In arXiv:1101.4919, Franceschini et al have summarized constraints from the LHC's CMS and ATLAS experiments on virtual graviton production. For the calculation of the contributions from virtual gravitons one needs to introduce a cut-off Λ of dimension energy that, next to the lowered Planck scale, becomes another parameter of the result. The constraints are then shown as contour plots in a two parameter space, the one parameter being the 'true' fundamental Planck scale, here denoted M_D, and the other one being mentioned cut-off, or its ratio to M_D respectively. One would expect the cut-off to be in the range of the lowered Planck-scale, though it might be off by a factor 2π or so, so the ratio should be of the order one. The figure below (Fig. 6 from arXiv:1101.4919) shows the bounds for the case of 4 additional spacelike dimensions:

The continuous line is the constraint from CMS data (after 36/pb integrated luminosity. Don't know what that means? Read this), and the dashed line is the constraint from ATLAS. The shaded area shows the excluded area. As you can see, a big part of the parameter space for values in the popular TeV range is meanwhile excluded.

Now what about the black holes? A black hole with a mass a few times the lowered Planck mass would already be well described by Hawking's calculation for particle emission, usually called Hawking-radiation. It would have a temperature (or average energy of primary emitted particles) of some hundred GeV. Just statistically, a big fraction of the emitted particles carry color charges and are not directly detected, but they form color strings that subsequently decay into a shower of hadrons, ie color neutral particles (pions, protons, etc). This process is called hadronization, and the event is called a jet. Depending on how many jets you get, it's a di-jet, tri-jet or multi-jet. The black hole's Hawking radiation would typically make a lot of particles and thus contribute to the multi-jets. One expects some multi-jets already from usual standard-model processes ("the background"), but the production of black holes should significantly increase the number. The figure below (from this paper by the CMS collaboration) shows an actual multi-jet event at the LHC:


In the paper arXiv:1012.3375 [hep-ex], the CMS collaboration summarized constraints on the lower mass of black holes in models with extra dimensions. For this, they analyzed the amount of multi-jet events in their data. The figure below (Fig 2 from arXiv:1012.3375) contrasts the predictions from the Standard Model with those of models with black hole production, for events with multiplicity N larger than 3 (that includes jets, but also photons, electrons and muons that don't hadronize).

On the vertical axis is the number of multi-jet events per bin of 100 GeV, on the horizontal axis the total transverse energy of the event (if you don't know what that means think of it as just the total energy). The solid blue line is the Standard Model prediction, the shaded area depicts the uncertainty. The various dotted and dashed lines are the predictions for the number of such events for different values of the minimal black hole mass, usually assumed to be in the range of the lowered Planck scale. These lines are created by use of event generators, ie numerical simulations. From this and similar data, the CMS collaboration is able to conclude that they haven't seen any black holes for minimum masses up to 4.5 TeV. CMS has an update on these constraints here, where they've pushed the limits up to 5 TeV, if not with amazingly high confidence level.

Some comments are in order though for the latter analysis. It argues with the production of multi-jets by black holes. This is a reliable prediction only for black holes produced with masses at least a few times above the lowered Planck scale. The reason is that a black hole of Planck mass is a quantum gravitational object and it is not correctly described by Hawking's semi-classical calculation. How to correctly describe it, nobody really knows. It is for the sake of numerics typically assumed that a black hole of Planck mass makes a final decay into a few particles. But that's got nothing to do with theory, it is literally just a subroutine in a code that randomly chooses some particles and their momenta such that all conservation laws are fulfilled. (The codes are shareware, look it up if you don't believe it.)

That procedure wouldn't be a problem if that was just some pragmatic measure to deal with the situation that has no impact on the prediction. Unfortunately it is the case that almost all black holes that would be produced at the LHC would be produced in the quantum gravitational regime. The reason is simply that the LHC is a hadron collider, and all the energy from the protons is redistributed on its constituents (called partons). As a result of this, the vast majority of the black holes produced have masses as low as possible, ie close by the new Planck scale.

What that means is that it is actually far from clear what the CMS constraints on excess of multi-jets mean for the production of black holes. A similar argument was recently made by Seong Chan Park in Critical comment on the recent microscopic black hole search at the LHC, arXiv:1104.5129.

Summary: It clearly doesn't look good for models with a lowered Planck scale. While it is in many cases not possible to falsify a model, but just to implausify it, large extra dimensions are becoming less plausible by the day. Nevertheless, one should exert scientific caution and not jump to conclusions. The relevance of CMS constraints on multi-jets depends partly on assumptions about the black holes' final decay that are not theoretically justified.

Question for the experts: Why do the curves in Fig 2 of the CMS paper seem to have a bump around the mininum black hole mass even though N > N^min?

Stronger than the universe

Two weeks ago, we had hail here in Stockholm. At that time I was homewards bound on the highway, and that's where I would be staying for half an hour while rescue crew scratched a motorbike off the middle lane. On the radio run "Heartbreaker" by Dionne Warwick. It's one of these songs I've heard a million times but never listened to, girl in love, guy who doesn't call, same old story. "Why do you have to be a heartbreaker, When I was bein' what you want me to be?" I probably wouldn't call her either. There's Swedish "nyheter" on the other frequencies, but I already knew the weather was sucking greatly, the highway was clogged, and the rest I wouldn't understand anyway, that being the state of my Swedish. Hail drumming on the car roof, Dionne sang "My love is stronger than the universe," and the physicist in me couldn't avoid asking WTF is that supposed to mean? (It's not a four letter word. No, it isn't.)

Okay, so the universe is supposed to have a strength. It springs to mind the gravitational force exerted by all the mass in the universe. Since you can't place yourself outside the universe (probably where Dionne's guy sits) the question is what's the force acting on you while inside, caused by the expansion of the universe? Well, we know that bound systems up to galactic scales don't take part in the expansion, but let's forget that for a moment and pretend the universe would try to rip lovers apart on planetary surfaces. If Dionne's non-caller was as far away from her as he could possibly get on Earth, ie 10,000 km or so, the force comes to 10^-26N. Not very impressive. The laws of attraction might get you into trouble, but actually gravity is even weaker than the weak force.

No, we have to think about this differently. We should be asking what's the strength of the structure of the universe? So, as everybody knows, the universe is made of strings, and a string has a tension which is something like the square of the Planckmass, take or give some orders of magnitude. Putting all dimensionful units back in, that comes out to be about 10⁴⁴N. We could compare this to the force acting on Dionne on the surface of a neutron star, which is a measly 10¹⁴N. Yes, clearly, there's string theory on the radio. Though I suspect you'd get pretty much the same answer asking what it takes to break a link in a fundamental spin network.

Passing by the accident zone I contemplate the lack of friction and the forces at work. The radio plays Tori Amos, Little Earthquakes. It doesn't take much to rip us into pieces.

Four links to Paul Dirac

The other day I was wondering out aloud whether somebody had ever checked the average number of co-authors to the next Nobelprize winner, because sometimes it seems to me like everybody knows everybody in theoretical physics. And it's not even a small community. Well, I don't know if anybody has actually measured the diameter of the physics coauthor network, but I saw this morning that the AMS has a tool to calculate 'collaboration distance' which is pretty much self-explanatory:


So, let's see how far I'm away from Paul Dirac coauthor-wise...


Not so far actually, thanks to Lee. Dirac's paper on the list above is a Nature article from 1952 on the question "Is there an Aether?" What about Albert Einstein then?

And go:


With 5 links to Albert Einstein! That's less than I would have guessed. With 6 links you can probably connect any two authors.

Unfortunately, the AMS database doesn't seem to contain experimentalists. Neither could I find any description of the algorithm used. It runs amazingly fast, and it makes me a little suspicious that in no query I tried did I get two paths with the same length, though that might have been coincidence.

So, have fun playing around.

On the Importance of Phenomenology

Quantum gravity has the potential to revolutionize our understanding of space, time, and matter and with it redefine our own place in the world. While my main interest is in finding the fundamental theory, I work on the phenomenology of quantum gravity because there is a need for it. The quest for a theory of quantum gravity is more than 75 years old, and though a lot has been learned along the way we are still waiting for a theory of quantum gravity that is connected to and confirmed by data. There is no way around phenomenology one way or the other; it is the necessary connection between theory and experiment. Here I want to reflect on the role phenomenological models have played in the history of physics and why they play an important role also in our search for a theory of quantum gravity.

If you know one thing about theoretical physics, it's Albert Einstein's name. While Einstein was inspired and guided by his contemporaries, both in theory as well as in experiment, his achievements are remarkable examples for the power of pure thought combined with mathematics. Einstein is not the only example; Dirac's equation that describes relativistic particles with spin 1/2 is another case where an axiomatic approach lead to predictions that were later confirmed by experiment, leaving us in awe of genius and the beauty of equations.

In the history of science these examples are however rare, and it is exactly because of their rarity that they impress us. An axiomatic approach towards the reconciliation of general relativity and quantum mechanics will, I am sure, if pursued vigorously, eventually lead to success. But the question remains if pure thought is sufficient to find the right starting point, for there might be more than one, some of which leading to theories incompatible with observations. And an axiomatic top-down approach brings with it a heavy load of developing mathematical tools along the way, detours to insight that can take a long time. In the history of science, physicists have often taken the freedom to go ahead and write down phenomenological models that were indeed not justified by any solid basis. And while rightfully met with skepticism, again and again they have been successful with it, thereby helping along the development of more and more fundamental theories.

The above mentioned example of Dirac's equation an instructive one. In the non-relativistic limit, Dirac's equation in the presence of an electromagnetic field reduces to the Pauli-equation which describes the coupling of electrons to electromagnetic fields with a gyromagnetic ratio of 2. It was derived by Dirac from his equation in 1928, but already in 1925 two Dutch graduate students, Samuel Goudsmit and Georg Uhlenbeg, had used a phenomenological model to describe the structure of atoms and the response of ions to magnetic fields. Their model did not make much sense since, classically, the gyromagnetic ratio should be one. Naturally, many physicists were not convinced by the model and Pauli even advised the students not to publish it. Yet, it described experiments well and Dirac's later derivation of their model from his equation served to document the validity of Dirac's theory.

Another example is Pauli's exclusion principle, according to which no two fermions can occupy the same state. It was postulated and used since 1925, among other things to explain the Zeeman effect. Yet it was not until the development of quantum field theory and an understanding of the properties of multi-particle states in 1940 that a derivation was achieved.

Coulomb's law, Ampere's law and Biot-Savart's law can be derived from Maxwell's equations, but they were known and in use long before that, significantly contributing to the development of the full theory of electrodynamics. Fermi's theory we know today is an approximation of the electroweak gauge theory, but was in use long before that, teaching us lessons in renormalizability. The Rahleigh-Jeans law and Wien's law for the spectrum of thermal radiation were combined in Planck's law. In 1900, Planck constructed a derivation for this radiation spectrum based on the, back then unfounded, assumption that the energy of photons is quantized and proportional to the frequency. It predated Einstein's explanation for the photoelectric effect by 5 years. The constant of proportionality that Planck introduced is now called Planck's constant and it was the starting shot for quantum mechanics.

Due to the difficulty to analytically describe the formation of bound states in Quantum Chromodynamics (QCD is asymptotically free, ie it's easier to deal with it the higher the energy) still today most of the models used are phenomenological and many predate the development of QCD. There is for example the the Nambu-Jona-Lasinio model, the Gell-Mann-Levy model or the String-Lund model, all of which have significantly contributed to our understanding of the structure of elementary matter.

One could at this point speculate which present day phenomenological models will turn out to have lead the way towards the now searched-for theory describing the fundamentals of space and time. It springs to mind String cosmology and Loop Quantum Cosmology, searches for deviations from Lorentz-invariance, extra dimensions, or signatures of space-time discreteness. The models currently in use are not derived from a fundamental theory. Instead, they aim to incorporate and allow tests for specific features the fundamental theory might have, like additional dimensions or modified Lorentz-invariance. But these models, even if they turn out to be incompatible with experiment, are guides on our search for the correct theory. Guides that, after 75 years, we have good use for.

Interna

Lara and Gloria are now five months old. They have made a lot of progress in coordinating their movements. They can now grab and hold things, including other peoples' noses and glasses, and they try to hold their bottles and spoons. We've bought some first picture books and they look with big eyes at the images while Stefan and I practice Swedish vocabulary: En elefant, två körsbär, tre ballonger, fyra muffins... Yesterday, Gloria rolled over for the first time.

Stefan makes an admirable stay-at-home daddy, who has even taken on the pretty much futile task of folding my T-shirts and pairing my socks. I meanwhile am back sitting in seminars, talking physics over coffee, sorting though piles of papers. Unfortunately, I still seem to spend a lot of time on the phone with the social insurance who still hasn't paid a single cent of my parental benefits. It turned out that they mistakenly believed I had moved out of country. The good news of the week is that I received a letter confirming I am indeed still insured with them and hope now things will finally be sorted out. It's about time since my account balance has been monotonically decreasing since October and the pain at the pump is substantial.

If you're a parent it is almost unavoidable that friends send you all sorts of baby-related information. Here are some of the more interesting articles that I came across: If your baby sleeps more than usual, expect a growth spurt, Statistically, mothers of twins live longer than other moms (it's a correlation, not a causation), for women with jobs that require a high skill level, having children significantly reduces their average lifetime income, and Nature Jobs reports that the gender divide in physics spans the globe:

"Balancing motherhood and work continues to be the biggest career challenge for women. Carola Meyer, an investigator at the Peter Grünberg Institute in Jülich, Germany, and vice speaker of the German Physical Society's gender-equality working group, says that although institutes and funding bodies provide career breaks for people who wish to have children, such schemes don't necessarily ease the balancing act. Women hold 17% of the 42 positions at her institute — a relatively large proportion, says Meyer. Yet all are under 40 and have no children. Those who want to rise within the scientific community can't consider having children until they are established, she says."

That stinks like a self-fulfilling prophecy. Let me clean up the stink by a quotation from the (otherwise cute but unremarkable) movie "Little Miss Sunshine" (that I watched on a flight on the way to some conference):

"Do what you love, and fuck the rest."

The cube of physical theories

Stefan has a lot of books. And most of them are about physics. The other day I picked a random book and opened a random page and saw myself faced with the "cube de théories physiques" (the cube of physical theories) in the book "De l'importance d'être une constante" by Jean-Philippe Uzan and Bénédicte Leclercq. You find a nice, though very French, illustration of that cube here. There is also an English translation of that book ("The natural laws of the universe: understanding fundamental constants") which has an English, though somewhat unsightly version of the cube on page 57. For your convenience, I've redrawn the illustration:



It shows a coordinate system with three axis that depict the values of three fundamental constants, G, ℏ, and 1/c – the coupling constant of gravity, Planck's constant and the inverse of the speed of light. To our best present knowledge these constants are indeed constant, but you can imagine varying them and ask what happens to the theory then. In many cases this corresponds to some physical limit. For example, if your theory contains terms in v/c, where v is velocity, then the limit of velocities small compared to c (i.e. non-relativistic) formally corresponds to taking c to infinity, ie 1/c to zero.

The cube seems to go back to Gamow, Ivanenko and Landau about a century ago, who allegedly cooked it up for a paper to impress a girl. It was rediscovered about 50 years later by some Russian guy named Okun, and then again by the Frenchmen who wrote above mentioned book. You can find here (PDF) a translation of the original paper by Gamow, Ivanenko and Landau, together with a comment by Okun.

You'd surprise me if you've seen that cube before. It is certainly not a particularly deep illustration, but it's inspirational and it gives you food for thought.

My trouble with popular physics books, though, is that in some cases you better not think about what you read because you might get terribly confused. That's what happened to me in this case.

To begin with it isn't clear to me what, physically, corresponds to varying G which is essentially the strength by which matter deforms the background geometry. It would seem more illustrative to e.g. take a constant with dimension of an energy density, so one could think of varying it as considering higher and lower energy densities. And taking the limit G to zero does decouple all the matter but doesn't actually give Special Relativity. Special Relativity is the limit of the vanishing of the curvature tensor or, equivalently, that of flat Minkowski space. Yet General Relativity has nontrivial vacuum solutions even in the absence of matter. These are Ricci-flat, but the curvature tensor doesn't necessarily also vanish. So there's something fishy about the front, lower left corner.

Also, it is to some degree of course a question of terminology, but what is usually referred to as the Newtonian limit of General Relativity is not the limit of velocities small compared to the speed of light. Instead, it is the limit of small distortions to the background, so there's something fishy about the back, upper left corner too.

What the nonzero value of all of these constants in the top, upper left corner has to do with a unification of all particle interactions is entirely unclear to me, and what the non-relativistic limit of that theory is good for I don't really know, though it arguably exists.

There is also the question whether taking these limits does actually commute, or if not approaching a corner does depend on the direction one is coming from. You can for example reach the corner with G and ℏ equal zero while keeping the ratio (the Planck mass) fixed. Or you can let them go to zero at a different pace so that the ratio goes to zero or infinity. It seems to me the difference should play a role, yet the diagram makes no distinction.

All together, the "cube of theories" is a very appealing representation. But do not wonder if it confuses you – it has to be taken with a large grain of salt.

Interna

So we've made it to Stockholm, but presently life is chaos. The plan was that I drive the household to Sweden by car and Stefan and the babies take a flight two days later so I can pick them up at the Arlanda airport. During packing however, we noticed the car was leaking oil and thought it was a good idea to have this checked in advance of a 1,500 km trip. Turned out the oil belongs to the servo steering and some broken hose would have to be replaced. I'm driving a Saab and the missing part had to be shipped from Sweden. By the time I wanted to leave, the hose was nowhere in sight. The mechanic advised us not to take longer trips. A cheerful Saab dealer however said not to worry, Autobahn is mostly straight driving anyway and who cares about the steering. I got a paper with the number of the broken part and a bottle of oil and he wished me good luck.

To his credit, I made it to Stockholm without problems. Problems started upon arrival. You see, I am living in a one bedroom apartment that's just about large enough for one person. The issue isn't so much lacking space as a lot of bulky, not to mention ugly, furniture of my landlord's wife that I can neither trow away nor sell nor move to the basement because the basement is full with her stuff too. The apartment has a second bedroom that the landlord told me last year he'd move out so we can use it as a nursery. Apparently he changed his mind about this some months ago and didn't bother telling me. The result is that now the four of us live in a clogged one bedroom apartment. One can't turn around without knocking something over and just hope that it doesn't hit a baby.

The internet wasn't working because the account hadn't been used for several months. The contract runs on my landlord's name and the company wouldn't give me the password. I tried to clean the apartment upon which my landlord's 20+ years old vacuum cleaner died with a small poof and a little black cloud and blowing a fuse. I sorted through a huge pile of mail that while consisting mostly of advertisement contains some serious looking påminnelse, and I know just enough Swedish to understand this means I should have done something long ago. I bought a new vacuum cleaner on the way to the airport.

The babies' first flight went well though Stefan reports Lufthansa staff wasn't very helpful. Since the baby seats don't fit on the baggage carts, he actually had to carry both babies and two bags to the gate. The apartment complex I live is gated and when we came back the gate was open. I dropped Stefan, the babies and the vacuum cleaner in front of the door and then found the gate locked on the way out. I noticed then that the key my landlord gave me didn't fit. I jumped upon the next person that came along, but she didn't speak English. After a considerable amount of time, I finally managed to find someone to let me out just to notice that I couldn't park the car in the garage because they were doing some repair. Stefan later found out that I did have a key to the gate, just that my landlord mixed up the labels and the key to the gate was labelled with 'basement.'

Inspecting the fuse box, Stefan reported he'd last seen these things in the late 70s. We spent a full hour searching for spare fuses and found them on the fuse box. Stefan drove to IKEA to get beds for the babies. I noticed that while they do sell in Sweden the formula we're using, they have different labels. Last time I tried to give Lara a different formula she actually refused to drink it, so I meant to call customer service. Just that, without internet, I couldn't find out the number. I had to call my mother to look it up. The winner of the day is the Hipp customer service that actually has human beings taking calls, and a friendly woman answered my question before I had even finished it. (The German A1 milk is the Swedish E2.) The German mobile phone company sends a warning about my roaming fees exceeding EUR 100 this month. A stressed daddy doesn't properly fit the diaper and Lara pees all over her cloths.

Between humoring the babies, changing diapers and noticing we have no diaper pail, unpacking my boxes and trying to fix a leaking tap, I called the social insurance to ask them for the umpteenth time why I still haven't received my parental benefits. A very confused sounding women told me that might be because I'm not registered with them anymore. Didn't I move out of country? (I think the next generation of cellphones should come with a little plastic pad to sink teeth into. Some of our baby toys have them too.) Having convinced her that I actually still live and work in Sweden, she said, well, but my husband doesn't. So they'll have to wait what the Germans do about his benefits. Just that the Germans tell us they're waiting for the Swedes to decide about my benefits. I must have left some impression on the women because she put something in my file that prompted somebody to call me back within 3 hours and assure me they're working on the case. But I estimate chances I'll have any money incoming to my bank account in the near future are slim.

Tried to take the babies for a walk. The twin stroller doesn't fit through the apartment door.

Late May in Sweden the days are very long. Being used to sleeping in the dark, the babies and me were up at 4am, hoping this day won't be quite as messy. Despite the mess, I'm looking forward to going back to work on Monday. Oh, and I wrote a paper. On the foundations of quantum mechanics, no really. I'll upload it sometime next week.

Basically, this is just to explain why I haven't done any substantial blogging for a while. But at least the internet connection is working again. Have to go change diapers now...

Filter bubbles

Our democracies rely on informed decision making. The internet is an asset when it comes to sharing of information, but as with any tool it needs to be used properly for the desired effect. The problem today is that we have too much available information and in order to make any sort of decision - and in order to find time to eat and sleep - we need to filter this information. From an evolutionary perspective, this is not a new problem in that our brains constantly filter information and only process the most relevant parts. That has advantages and disadvantages. What is new about the filtering we need for online information is that the filters are designed by some software engineers rather than by Nature, and they haven't proven their usefulness during thousands of years.

The risks that come with the filtering of information are a returning theme on this blog. In my post The Spirits that We Called I argued that the right filtering of information is crucial because people don't make a lot of effort questioning the order or relevance of information. If it doesn't come "cheaply," in the sense of it not requiring time and effort, it's likely to have low impact, thus the importance of search engines and social networks for democracy. From an evolutionary perspective the limiting of time spent on information gathering is just a careful dealing with resources and not irrational at all. That has always been the case, but the internet vastly centralizes provision of information and amplifies its impact at the same time. The consequence to draw, as I argued in my post Can Technology make us happy?, is that we should be very careful with designing information structure and filters. Do we really get the information that we need? One of the biggest problems, I think, is The Illusion of Knowledge that leads people to believe they have all the relevant information already.

Some days ago I saw the below TED talk by Eli Pariser, who makes this point extremely well. If you have ten minutes of time, they are well spend on the below video.

On the measurement of happiness

You might think it's the individual's pursuit of happiness that is the driving force behind our societies' dynamics, the progress as well as the regress. At least I thought that for a long time. And then, some years back, during a talk by Stuart Kauffman, it occurred to me this doesn't make sense and, worse, it's actually not true.

It doesn't make sense because from an evolutionary perspective the driving force is survival. It just happens to be beneficial for your survival if you're happy about actions that eventually produce healthy offspring. But if you think about happiness as some biochemical reaction it's not an end unto itself: For keeping your body supplied with energy it's actually irrelevant if you like eating. The reward circuit that triggers dopamine release is just a handy neurological tool to memorize the dos and don'ts. And you don't have to look far to figure that people don't make decisions to optimize happiness in the first place. There are, just to pick one example, many studies showing vicinity to nature (forest, parks, beach etc) improves not only people's self-declared happiness but also their health and life-expectancy. Yet, most people live in cities and spend their time indoors. Why?

In the wealthier nations on the planet, word has it that money doesn't make happy and even politicians and economists have come around to seeing that the GDP is far from measuring well-being. British Prime Minister David Cameron has set out to measure the Brits mood by means of a national happiness index, the French too have created a Commission to assess happiness, and residents of Somerville have recently been asked to fill out a questionnaire about their life satisfaction. We will certainly see more efforts into this direction. But this left me wondering. What quantity it that the Brits, the French, the Americans aim to optimize here? And do we really want that?

I'm not an economist, but I know so much as that the question how to optimize collective happiness is not new to economists. If you want to determine the "national well-being" you inevitably have to sum, or aggregate in other ways, different people's happiness. Yours and mine and that of my babies. And do they all count the same? How does your happiness compare to mine? How many ways are there to aggregate, and which one is the right? How do you, objectively, measure it? Can you at all?

People have tried, and are trying, seriously, to determine the amount of happiness as a neurological reaction, a red on an fMRI or a peak in a hormone level with the aim to eventually determine a 'true' value of stuff essentially. Yet 100 years ago most economists abandoned an inter-individually comparable happiness in favor of a measure of preferences that cannot and, interestingly, doesn't have to be compared between you and me. They call it the utility function.

The utility function works well on an individual level, but leaves an ambiguity among different possible optima as to which is the collectively preferable one. The aggregation would necessitate a 'social welfare function' which is basically the weight for everybodies' happiness in order to sum it up and it is ambiguous - call it the measurement problem of economy. Lacking a rationale for one particular choice, for the hard-core neo-conservative it's a capital DONT. And, from a theoretical basis, a justified one. But all these attempts to measure happiness then bring us back to this century-old question: What do we want? And what's the rationale for it?

To illustrate the problem, consider you are redistributing money from the rich to the poor. You do it on the premise that taking $10 away from a billionaire will decrease his happiness less than it will raise the happiness of a starving child in Africa. But how do you know if you can't compare their happiness? And if you would indeed measure their brain activity should the ability to produce high dopamine levels, that is to some extent genetic and age dependent, affect your decision?

In all this discussion, nobody ever questions that it is actually happiness that we want. But beware the self-evident assumptions for I am here to disagree. So I argue what we are really pursuing both individually and collectively is not happiness, it is the maximization of possibilities. Money doesn't make happy. It opens possibilities. You don't move to the city because it makes you happy, but because it opens doors, increases the number of available mates, and enriches your nightlife. The relevant point is that the number of possibilities is not weighted. It's just a number. You can add it and you can compare it. So here's the rationale for giving the tenner to the starving child. The billionaires' options are hardly affected. Yet the money has a large impact on the child's health and education. It opens a large number of future possibilities, more than it closes for the billionaire.

You can find a writeup of my thoughts on the Social Science Research Network (that's the humanists' arXiv):

On the Problem of Measuring Happiness
http://ssrn.com/abstract=1754423

Hello from Perimeter Institute

Sorry for the silence. I seem to have caught a stomach bug on the trip to Canada and spent the better half of the week commuting between bed and bathroom. I'll call it the Air Canada diet. Nothing quite like it to get rid of that excess pregnancy weight.

The construction at Perimeter Institute has been progressing well. The new part of the building is supposed to be finished sometime early fall or so, and I hear they're still on schedule. (See here for the photos from last year.)




The main entrance to the building is well hidden between fences, walls, and various dangerous looking machinery. Its location seems to be changing by the day like some secret code. The reception has been replaced by a study area, the bistro is now in the lobby, and staff features some new, unfamiliar faces. Still, after the last year's many changes in my life, it is comforting to come back and find things are still like they've always been. People are still talking about spin foams and black holes and their favorite interpretation of quantum mechanics. They still drink too much coffee and on your way to Starbucks on a Sunday morning you might run into the director. Waterloo is really a small town and the physicists' universe is expanding while they're orbiting around the center of their own gravity.

Interna

I am flying to Toronto on the weekend and will be visiting Perimeter Institute the coming two weeks. Since Superdaddy will be terribly busy and need all four hands for cleaning baby butts, and I'll be jetlagged and otherwise try to figure out what to write in the visit report, you're facing a slow time on this blog. When I'm back, Stefan, the babies, and I will pack our bags for we are spending 6 weeks in Stockholm so I can go back to work, at least temporarily.

Lara and Gloria are now exactly four months old. They are holding their heads well and grab everything that comes sufficiently close to their nose. They are also both trying to roll over, but haven't really managed yet. Lara is still the talker and Gloria is ceaseless in her daily workout. It seems that whenever I look at her, she's frantically waving her arms and kicking her legs. We've made some first attempts at spoonfeeding and were reminded that beta carotene is not water soluble.


The babies' paperwork is adding up. They're now registered also with the Swedish tax offices and have their own person-numbers. It turns out I'll have to apply for their residency in Sweden, so more forms waiting to be filled out. For the flight to Sweden, the girls got their own passport for which we had to get biometric photos. Even the babies manage to look like criminals on these photos.

So you want to get a PhD?

... then here's some things to consider:

The recent issue of Nature has a News Report "The PhD factory - The world is producing more PhDs than ever before. Is it time to stop?" which summarizes the job prospects of PhDs in Japan, China, Singapore, USA, Poland, Germany, Egypt and India.

“In some countries, including the United States and Japan, people who have trained at great length and expense to be researchers confront a dwindling number of academic jobs, and an industrial sector unable to take up the slack. Supply has outstripped demand [...]”

The below graphic (from mentioned Nature News article), shows the distribution of academic post-doctorate jobs in science and engineering in the USA:
This shows the unfortunate trend towards more and more research done by scientists on temporary contracts that we talked about in my earlier post Short-term Thinking.
Germany by and large seems to be doing well as far as job prospects are concerned, though few PhDs remain in academia:

“[In Germany] just under 6% of PhD graduates in science eventually go into full-time academic positions, and most will find research jobs in industry [...] The relatively low income of german academic staff makes leaving the university after the PhD a good option.”

That agrees with my experience.

But back to the USA. One of the over-produced PhD-students from Illinois, Sergey Popov, has developed a model according to which top US universities have economic incentives to lower their standards, because the better their students' grades the better their students' job prospects and the better the university's reputation (and finances) in return. The Times Higher Education cheerfully titles Elite US students are securing top jobs 'despite being less gifted' and summarize Popov's model:

“Universities "choose [a] grading standard to maximise the total wages of [their] graduates". [Popov] said his theory suggested that grade inflation would be highest in top universities [...] the risk was that the process went so far that there were Harvard graduates in top jobs who would not have got an A at Illinois and who had fewer academic gifts and social skills than every Illinois A-student. This, he said, was not "socially optimal".”

Popov has his data online on a website called gradeinflation.com. His model is interesting but there doesn't seem to be sufficient data to tell how well it actually describes reality. Anyway, I'm sure though it will leave some people chuckling. Did I see you grin? Did I?

Actually, the Scolarly Kitchen reports that the whole higher education thing might just be the next bubble to burst! That's at least according to Peter Thiel, founder of PayPal:

“Thiel’s belie[ves] that higher education is the next economic bubble into which we’ve moved the air expelled from Web 1.0 and housing.”

The cited data shows that College tuition fees have increased 375% since 1982-84 (3 year average).

And Scientific American has an editorial, Dr. No Money about the unpleasant duties of those PhDs who dare to remain in academia:

“Most scientists finance their laboratories (and often even their own salaries) by applying to government agencies and private foundations for grants. The process has become a major time sink. In 2007 a U.S. government study found that university faculty members spend about 40 percent of their research time navigating the bureaucratic labyrinth, and the situation is no better in Europe. An experimental physicist at Columbia University says he once calculated that some grants he was seeking had a net negative value: they would not even pay for the time that applicants and peer reviewers spent on them.”

So you want to get a PhD...