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...

Robert Bosch Foundation: Seven points to improve research

In the aftermath of the plagiarism affair that led to the withdrawal of German defense minister zu Guttenberg's doctor title and, eventually, his resignation, the Robert Bosch Foundation invited a panel of experts to formulate ways to improve the conditions under which research is conducted. The outcome is a seven point paper "to assure integrity and quality in scientific research." You can download the paper (PDF) here. Since it's in German (and I realized Google translate doesn't cope well with academic-style German), here is a rough translation:

(All awkward grammar is entirely my fault.)

"1. Mitigation of publication flood

The number of publications around the world should be reduced (relative to the growing number of scientists) and thus - against the economic interests of publishers - also the number of journals. This is the only way to ensure that this important basis for assessing the quality of research will again consist of reflected and carefully evaluated results. And only then researchers will be able to again take sufficient note of relevant results and findings from their field.

2. Basic insights need permanent funding

Science needs durable and reliable funding, because the search for something new and for an increased understanding of nature follows radically different laws than a commercial enterprise. Of course academic institutions have to deal responsibly with their funds. We have to vehemently object however the expectation that academic institutions have to make direct financial profit or are evaluated by strongly economically oriented criteria. Rather, we should work together, even more than is already done today, to highlight the high intrinsic value of knowledge gain for the general public.

3. More emphasis on the content of scientific achievements

In the allocation of research funds it should be content that is assessed, not mindless promises of success of practical implementation. The qualitative assessment of the scientific work of a scientist or a researcher should at least equal in importance the quantitative bibliometric performance indicators. The sheer number of publications is not a valid criterion.

4. Proscription of strategic authorship

Authorship of a scientific publication requires substantial contribution to the content of to-be-published work. Authorship has become a currency of science, which is rewarded with money. The system for performance-based allocation of funds should therefore carefully investigate the actual contributions of the authors and proscribe a merely strategic authorship without substantial participation.

5. Researchers must write their own research proposals

External funding is an important competitive component of the academic system. Due to the trend to demand very high shares of external funding, the pressure has increased so much that a professional application system has formed, one in which scientists no longer write the research proposals themselves, but, in extreme cases, agencies formulate standardized applications. But scientific concepts need to be written by the researchers themselves. Ghostwriters must not be tolerated, not even in composite applications where parts written by different scientists are often "smoothed" by agencies.

6. Transparency in the presentation of data collection

Science needs transparency, despite the increasing complexity. Rapid technological progress, together with an excessive competition leads to more complex, and difficult to verify experiments. Without transparent and accurate representations of data collection and the scientific approach undertaken, more mistakes and improbities occur which jeopardizes the substance of science.

7. Good research takes time

Development and implementation of sound projects are not compatible with short-term contracts. The pressure generated by short-term contracts leads scientists and researchers to carry out small projects with no substantial knowledge gain and to publish fragments. Only contract terms that offer, through sensible conditions, the possibilities to plan long-term projects (esp. for young researchers) allow the quality of research indispensable for international competition."

This sounds very Germenglish, even to me ;-) Gee, all these many-syllable words and convulated grammatic constructs. I had to look up "improbity," and I'm not even sure I know what the German translation "Unredlichkeit" means (literally it means "something one doesn't speak of"). In any case, I hope it's roughly understandable. I think these are all very good points. However, I wasn't even aware that ghostwriting of proposals is an issue, I've never heard of this.

Do you have anything to add?

You are Ein Stein

Earlier this year, Gideon Rachman asked in the Financial Times "Where have all the thinkers gone?" Contemplating the Foreign Policy list of the Top 100 Global Thinkers 2010 and comparing it to who might have been on that list 150 years ago, he finds today's "crop of thinkers seem[s] unimpressive" and it gives him "the impression that we are living in a trivial age." Rachman proposes several explanations for this impression of his. We may only recognize great thinkers for what they are when enough time has passed. We may not appreciate them as long as they are living, breathing things who burp and dye their graying hair. Today's intellectual giants may live in China and the Financial Times hasn't heard of them. Or, the times of great thinkers are over due to specialized networks:

"In the modern world more people have access to knowledge and the ability to publish. The internet also makes collaboration much easier and modern universities promote specialisation. So it could be that the way that knowledge advances these days is through networks of specialists working together, across the globe – rather than through a single, towering intellect pulling together a great theory in the reading room of the British Museum."

Jonah Lehrer from The Frontal Cortex speculates that the apparent dearth of intellectuals is due to the "lessened importance of the individual" because "the era of the lone genius is coming to an end," for which he cites a study showing that teamwork and collaboration is on the rise in modern research.

There's the obvious thing to say about Lehrer's argument. There has never been something like a lone genius. You don't contribute to a society's knowledge and well-being without being part of that society. Scientific research has never been done in intellectual vacuum. All the great thinkers had their friends, their correspondences, their mentors and colleagues. But maybe more important, that teamwork is on the rise doesn't lessen the importance of the individual. It just integrates it better and, truth be said, makes it less apparent. But either way, it is questionable that the number of peer reviewed articles from large collaborations has anything to do with intellectuals to begin with.

I think the reasons for Rachman's impression are more mundane. He is probably right with the suggestion that it is difficult to recognize a great thinker while they're still thinking. There's 7 billions people on the planet and all of them have something to say. A lot of them say smart things occasionally, some say smart things most of the time, but all that smartness may turn out to be bullshit anyway. Take that guy Kurzweil with his Singularity prediction for 2045. Chances are, in the year 2045 he'll be little more than a curiosity. And some people that today might appear completely nuts will turn out to be right on the spot. Time will tell, so give it time.

The only real possibility there won't be no intellectuals in the future (aside from stupidity spreading and progress stagnating) is that thinking indeed becomes truly collective. However, as I argued in my earlier post on Collective Intelligence, we are far from that. In today's collaborations knowledge is not emergent. It is not something that really happens on the collective level. It is simply an assembly of many small parts. Yes, the parts profit from the other parts' contributions and if you put a group of smart people together they can work with each others contribution faster, but it's still a piece-by-piece work.

The prototypical example for a system that is more than the sum of its pieces is a frog. If assembled correctly, it croaks and jumps and that's emergent features. The prototypical example for a system that is the sum of its pieces is lot of bricks. It gets you a wall, alright, and maybe even a house. But it doesn't actually acquire new abilities. Today's specialist networks are brick walls, not frogs. The thinking still has to be done by the individual. We're all just bricks in the wall.

"Ein Stein" is German for "a stone."

So what do you think? Do you share Rachman's impression that today's intellectuals are disappointing? And if so, what do you think the reason is?

Multiversing around

multiverse [noun]

From L. multus “much, many” and L. versare “to busy oneself,” lit. “to turn to.” Tech: A hypothetical collection of different variants of -> universes. Colloq: A large collection of no apparent purpose. Expl: “She has a whole multiverse of shoes,” “His essay received a multiverse of comments.”

I am considering to consider to read Brian Greene’s new book The Hidden Reality on the multiverse. On the pro side there’s a likely readable synopsis of an interesting topic. On the con side there’s two of Greene’s books in my shelf that I never finished reading. A writing therapy exercise I thought might be useful.

First, let’s get over with the terminology. Yes, multiverse is a disingenuous nomenclature. If the universe is by definition all that exists, then anything to the multiverse more than the universe does by the same definition not exist. But it’s moot to complain about terminology that has already become common use. What exactly the multiverse is depends on the context, but in either case it’s something that exists in addition to what the presently most widely accepted theories let physicists expect to observe. Some theories seem to imply the existence of “more,” of a multiverse of “more,” and that in other ways than “more of the same.”

Multi versus uni

The central question is what does it mean “to exist?” As a particle physicist I’d say something that can’t be observed doesn’t exist. (Observation doesn’t necessarily mean a direct interaction.) Talking about the “existence” of something that can’t be observed opens the door to fairy tales. Though my invisible friend disapproves, from a scientific point of view I am interested in the multiverse only if it’s observable. And even then my interest is very limited since I find the presently discussed possibilities of observation remote and implausible. But yes, there are versions of the multiverse that may have observable consequences. Eg. we recently discussed a paper on signatures of bubble collisions in eternal inflation, one possible multiverse scenario, and there’s Laura Mersisni’s superhorizon entanglement giving rise to the giant void, and related stories.

For the more entertaining part I’ll now take off my physicist’s hat (okay, it’s an Einstein wig really) and put on my hobby philosopher hat (if you really want to know, it’s actually a tea pot lid).

multiversal [adj]

From noun -> multiverse. Colloq: Of confusing variety. Expl: “By the year 2010, social networking had become multiversal,” “The promises during the election campaign were multiversal.”

A lot of effort has been spent on the search for a “Theory of Everything.” Commonly meant to be a theory unifying General Relativity with the Standard Model of particle physics, it is another misnomer in common use: It is unlikely that a reductionist approach will ever be able to actually explain everything, not in practice and maybe not even in theory. I will however refer here to a TOE in the more general sense as a theory that leaves us with no “Why” questions and reduces all of science to a question of “How” and, knocking on the teapot lid, I’ll refrain from pointing out that we can never know if we’ve found it.

What may such a TOE look like? None of the currently pursued approaches to grand unification or quantum gravity comes even close. Even if string theory or something similar would allow us to compute all the parameters in the Standard Model and in the ΛCDM model, and so on, Nobelprizes would be handed out for certain, but it would just move the Why’s elsewhere, for all these theories have other unexplained assumptions: Why are strings/ loops/ E8/ networks fundamental? Why causality? Why these initial conditions? Why quantization? Why a semi-classical or classical limit? Why matter? Why in fact anything instead of nothing?

For this TOE we cannot use an assumption that constrains the theory to reproduce observation. The only guidance eventually left is mathematical consistency. Most occurrences of the multiverse actually still have additional assumptions, but already the problem is the same: too many possibilities. If you don’t want to settle for a “just because,” a question without answer, an unexplained final cause, you have to swallow that all that can exist, according to current theories, does exist. That doesn’t answer the question, but it removes the need for an answer. That is, in a nutshell, the reason for the recurrence of the multiverse in various branches of theoretical physics: Mathematical consistency just isn’t enough.

(A probabilistic approach for the multiverse with the assumption that our universe is one of the common ones, trying to derive some features of our universe at least as probable, is a reentry into the question-room through the backdoor. It just rephrases the question why our universe is special and what theory allows us to derive the details, to the question why our universe is especially unspecial and what measure allows us to derive the details, and it makes additional assumptions about how to compute probabilities rspt. about the logic used etc. I’m not dismissing the attempts to define a probability measure on the multiverse as useless since sometimes looking at an old problem from a new direction is fruitful. But the attempt in itself isn’t actually progress.)

Mathematical consistency is not a strong requirement. The complex plane and holomorphic functions on it for example are mathematically consistent (unless you insist on some wrong theorem), so is linear algebra on n-dimensional vector spaces. What sort of a universe is that, you might ask. But if mathematical consistency is all that you’re left with, that’s what you get: Everything that’s mathematically consistent “exists” in the same sense as the world around us, a notion of “existence” not in agreement with that put forward by the strange person with the funny wig. This thought then brings us straight to Tegmark’s Mathematical Universe: All of mathematics is real, and all that’s real is mathematics. There is no distinction because there’s no other meaning to “existence.”

My problem with the Mathematical Universe is not that I dislike the idea of being made of math (whatever that might mean). In fact, I quite like the idea (up to a face factor). My problem is that for all I can tell it’s not of use for anything (oops, lid slipped off) and it is based on an assumption I don’t find particularly plausible: That humans in the 21st century have already found the language to describe the fundamental nature of reality.

Formal mathematics is a quite recent achievement in mankind’s evolution. Sure, its precision and usefulness in the description of nature is vastly superior to that of, say, the English language. But 50,000 years ago our ancestors have thought of their precise spoken language as the ultimate tool to describe nature, vastly superior to grunting and waving with paws. So how sure really can we be mathematics is so intimately connected to nature that nature is mathematics?

Versus multi

Now let us turn the argument around. Searching for a TOE we were ultimately left with mathematical consistency as only guidance and it’s not enough of a constraint. It offers too many possibilities and eventually doesn’t explain anything. Unless, that is, mathematical consistency is not the only requirement. (There is of course the requirement to reproduce observation, but that’s too pragmatic for my tea pot.) The only way to avoid a multiverse then seems to be that mathematics is not sufficient to describe the fundamental nature of reality.

So the options are: a) Accept a final cause. b) Accept the multiverse. c) Accept that there’s a way to describe nature better than with mathematics.

If you don’t like a) and b) and therefore have to sympathize with c) you are however left wondering what may describe nature even better than mathematics? Well, you can. Tegmark’s Mathematical Universe irks people because they believe there is a distinction between reality and mathematics, between platonic ideas and the world out there. The common point of view is that the math used in theoretical physics is a description of nature, but humans provide the map between reality and the math. It is possible that this mapping is itself a purely mathematical process. I can imagine there to be an algorithm that searches for mathematical definitions whose properties fit to observed data. Yet presently there is no answer to the question whether there is in fact such an algorithm able to do science like a human. Gödel’s incompleteness theorem is happily waving its tail, waiting for a chance to pee on your leg.

In summary this means if there is neither a final cause nor a multiverse, there likely won’t be any Singularity in 2045 either since no computer algorithm will be able to go beyond math. And vice versa, if a computer algorithm, coded in the language of math, is able to map every aspect of reality to a mathematical structure, then you’re likely stuck with the multiverse, Tegmarkian version, subsuming all other versions. It might then just be that the next revolution in physics comes from neuroscience.

multiverse [verb]

From noun -> multiverse. From L. multus “much, many” and versus, pp. of vertere “to turn.” To make many turns. Colloq: To act or talk incoherently. “She spent the afternoon multiversing around,” “His job interview was a disaster; he totally multiversed it.”

I’ll finish with a quotation from a wise physicist, who wants to remain unnamed but reportedly reads this blog: “The multiverse, the simulation hypothesis, modal realism, or the Singularity –it’s all the same nonsense, really.”

Citation Ponzi Sheme discovered

Berlin, April 1st 2011: The Federal Intelligence Service discovered a Ponzi scheme of academic citations lead by an unemployed particle physicist. A house search conducted in Berlin last week revealed material documenting the planning and administration of a profitable business of trading citations for travel reimbursement.

According to the Federal Intelligence Service, the hint came from researchers at Michigan University, Ann Arbor, who were analyzing the structure of citation networks in the academic community. In late 2010, their analysis pointed towards an exponentially growing cluster originating from a previously unconnected researcher based in Germany's capital. A member of the Ann Arbor group, who wants to remain unnamed, inquired about the biography of the young genius, named Al Bert, sparking such amount of activity. The researcher was easily able to find Dr. Bert scheduled for an unusual amount of seminars in locations all over the world, sometimes more than 4 per week. However, upon contacting the respective institutions, nobody could remember the seminars, which according to Prof. Dr. Dr. Hubert at The Advanced Institute is "Not at all unusual." The network researcher from Ann Arbor suspected Dr. Bert to be a fictitious person and notified the university whose email address Dr. Bert was still using.

It turned out Dr. Bert is not a fictitious person. Dr. Bert's graduated in 2006, but his contract at the university run out in 2008. After this, colleagues lost sight of Dr. Bert. He applied for unemployment benefits in October 2008. As the Federal Intelligence Service reported this Wednesday, he later founded an agency called 'High Impact' (the website has since been taken down) that offered to boost a paper's citation count. A user registered with an almost finished, but not yet published, paper and agreed to pay EUR 10 to Dr. Bert's agency for each citation his paper received above the author's average citation count at the time of registration. The user also agreed to cite 5 papers the agency would name. A registered user would earn EUR 10 for each recruitment of a new paper, possibly their own.

This rapidly created a growing network of researchers citing each others papers, and encouraged the authors to produce new papers, certain they would become well cited. Within only a few months, the network had spread from physics to other research fields. With each citation, Dr. Bert made an income. The algorithm he used to assign citations also ensured his own works became top cites. Yet, with many researchers suddenly having papers with several hundred citations above their previously average citation count, their fee went into some thousand dollars. On several instances Dr. Bert would suggest they invite him for a seminar at their institution and locate it in a non-existent room. He would then receive reimbursement for a fraudulent self-printed boarding pass, illegible due to an alleged malfunctioning printer.

Names of researchers subscribed to Dr. Bert's agency were not accessible at the time of writing.

Interna

Lara and Gloria are now almost three months old. They have doubled their birth weight and grown in and out of the newborn cloths. Gloria is smiling generously at all and everybody while Lara's smiles are reserved for special occasions. Stefan and I are glad they now make some sounds other than crying; their "ouee" and "agooh" are music to my tinnitus.

The girls can now almost hold their head, and they have begun to take note of the mobiles above their beds. Gloria spends hours waving around with her arms and kicking into the air, hoping to hit something. Lara happily talks to the wooden bees and butterflies above her head. Interestingly enough, the babies hardly take note of each other. When we put them both in the playpen, they completely ignore their sibling. They pay more attention to about everything else than they pay to their sister.

Responsibility hits you in funny ways. The other day it occurred to me with some months delay I should probably wash the babies behind their ears. If I don't do it, who will? And then there was the day when I misplaced the baby. I went to see if they're all right and found one bed empty. Since it was unlikely the baby had learned to walk while I wasn't looking, I probably took her someplace and then forgot. I checked the big bed and the babyseat and the playpen before I remembered I put her on the couch, where she was still sleeping peacefully. (But don't tell my husband.)

Stefan and I, we have meanwhile organized our lives with the babies pretty well, though we are still short on sleep. It didn't help that Europe switched to summer time yesterday. Today, Lara and Gloria seem a little confused that breakfast is so early. And I have learned to type two-handed while balancing a baby on my forearms.

What is mathematics good for?

Some weeks ago I asked my midwife what made her chose her job. She told me she had actually wanted to study medicine, but didn't meet the numerus clausus. Rspt she ranked place thirtythousandsomething. With an apologetic look at the shelves full with physics and maths books behind me, she added maths was her problem. She couldn't figure out what is was supposed to be good for.

She has a point there, I thought through endless repetitions of my pelvis floor exercises, and though it's hardly the first time I've heard this remark I started to wonder what role mathematics does really play in every day life. (Okay, I admit, what I really thought was it would make a good topic for a blog post.) Arguably, I need a lot of maths in my life because otherwise I'd be unemployed. But how much maths does the average person really need? And what do they need? And does school teach it?

You don't need to learn maths to survive. Otherwise mankind would have gone extinct long ago. Amazingly enough though, your brain performs some basic mathematics all the time, such as extrapolating the motion of moving objects. In an interesting experiment measuring the activity of neurons in rhesus monkeys, researchers from the University of Tübingen have found that different sets of neurons fire in response to the monkey seeing sets with different numbers of elements. Basically, there's neurons that are (primarily) activated by specific numbers. (See Bongard and Nieder, PNAS 107, 2277 (2010)). And it is known that people with certain brain injuries lose the ability to understand, compare, and deal with numbers, a disability known as acalculia. It does seem plausible then that dyscalculia, difficulties in learning and comprehending mathematics, is so some extend due to wiring instead of motivational problems. However, that's estimated to affect only a small percentage of the population. Most people who don't understand maths don't understand it because they've never really made an effort. Which brings us back to the question what's it good for?

Basic arithmetics is so universally useful that it benefits your selective advantage. Whether you want to know if you've enough money to fill up the tank, are worried that the baby didn't drink enough, or need to know how many bottles of sparkling wine to order for your graduation party, it haunts you everywhere. Beyond that, if you want to understand your average magazine or newspaper, you better know how to read a graph. And unless you want to blindly trust your financial adviser, percent calculation should be on your list.

Having come to this point, I Googled for "mathematics in every day life." The first hit was a long deserted blog with a handful of entries that, next to percent calculation, discusses symmetries in car logos and flowers. However, one doesn't need to know the mathematical definition of a group to plant a flower. Google further brought up a document I couldn't open, a file not found, a power point representation on photoshopping, and a Tutorvista question "How is maths used in everyday life?" with the reply "Math is used in time calculation, shopping, traveling, cooking, and all other important activities." All together not an impressive result. What is maths good for if not even Google knows?

School mathematics tends to drown pupils in 'real life' examples that no normal person will ever use in their real life. Yes, I sometimes add up the prices of items in the supermarket just for distraction, but it's arguably a pretty pointless exercise. Yes, it helps to know some trigonometry to figure out if the new furniture will actually fit through the door, but then you can rent furnished. And who really cares what's the volume of that piece of cake.

The real value of mathematics isn't that you can calculate what 500 sq ft is in international units, because Google does that for you. That, incidentally doesn't have much to do with maths anyway. Sadly, school doesn't teach children much about the beauty of maths, the value of logic, and the power of proofs. You don't need mathematics to live, but you need it to understand - for example Google's PageRank. What is mathematics good for? Mathematics is at the basics of science, including physics, computer science, and economics, examples are omnipresent in your every day life. Without mathematics, you're left in the fuzzy realm of storytelling. How can one understand the world without knowing what a differential equation is, without knowing what optimization is?

No, you don't need to know maths to plant a flower, to admire a night sky, or to like a crystal. But as in the arts, getting to know the artist and his techniques add to the appreciation and understanding of her work - may that be the Fermat's principle, data compression, self-organization, Noether's theorems or chaos. Mathematics is the language of Nature and learning it is your connection to the universe. No more and no less.

Since I acknowledge that the selection of maths taught at school is, sadly, suboptimal to this end, I set out to explain to my midwife that statistics is essential to understand the studies she's been telling me about and a doctor should indeed know what a standard deviation is. And being familiar with the exponential function might explain the funny face I made when she recommended some homeopathic remedy in D10. Things went downhill from there.

This and That

• APS's newest journal is Physical Review X (PRX). It's online-only, open access and accepted articles will be published upon payment of an article-processing charge of $1500. The website says the journal is "global." There's countries on this globe where $1500 makes an acceptable annual income. Just saying.


• Two years ago, we discussed Craig Hogan's papers on Holographic noise, and the shortcomings of his model. Hogan successfully postdicted the GEO600 mystery noise. After the noise turned out to be due to a readout error, Hogan found a missing factor in his calculation. According to the new calculation, the noise would not be seen at GEO600. Fermilab now funds a new experiment, called the Holometer, to test Hogan's model. The two papers listed on the website as reference are unpublished. Just saying.


• Am I the only one thinking "Frisch, Fromm, Fröhlich, Frei" when looking at the Fermilab logo?


• Zeitgeist: The US Air Force invites a professor of metaphysics to learn about the philosophy behind the nature of causality. Just saying...

Causes of women's underrepresentation in science

I always feel awkward if somebody brings up the topic of women's underrepresentation in physics. Though I'm one of these underrepresented women, I don't actually have a lot to say about the possible causes that hasn't been said a million times already. I'm not a social scientist and I'm not a neurologist and I don't follow the relevant literature. That leaves me with my own experience to talk about, but I generally dislike talking about myself. Also, exactly by virtue of being one of the aberrations I'm not the right person to ask why there aren't more girls studying physics.

I'm generally supportive of all these women's networks, especially those aiming at providing the all-important much talked about 'role models' for young girls - something that in today's overconnected world can be done without much effort - and groups dedicated to helping with issues that women are more likely to want to discuss (Breastfeeding in my office - do or don't?). I've on occasion participated in on or the other meeting and such, and I think most of these initiatives serve a good purpose in providing encouragement and connections to others in similar situations and can be very helpful indeed.

But thing is I get along well with my male colleagues and I have no reason to suspect any sort of systematic bias has conspired against me at any point. Of course one or the other guy is an asshole, but nothing surprising about that. Just that I know many of my female colleagues have made bad experiences and I don't want to do a disservice to them by saying I think much more important than gender bias is that the typical academic career is simply incompatible with many women's priorities. Do I have to spell it out? If you're lucky enough to get tenure, you'll on the average get there in the late thirties or early forties. If you're a man, you can then go marry a younger woman and start thinking about reproduction. If you're a woman, you better freeze some eggs in time if you want to wait that long.

Interestingly, I yesterday came across a paper examining the question if it's a bias against women causing their underrepresentation in science

Understanding current causes of women's underrepresentation in science
Stephen J. Ceci and Wendy M. Williams
PNAS February 7, 2011

In their paper the authors surveyed studies past the mid 80s on bias against women in manuscript and grant reviews and in hiring. They basically found that while there's the occasional outlying study claiming to have found a bias against women, these outlying results haven't been reproduced, and most studies found very little or no bias in either direction. (That is, one should add, after productivity has been corrected for by available resources since women are more likely to work in positions with limited resources which by itself is correlated with lower productivity.)

Now, as I said, I'm not an expert on these questions so it's hard for me to tell if their survey of available data is complete. But if it is, one should pay attention to their conclusions. They argue that looking at the evidence, or lack thereof, efforts to reduce gender bias are misdirected since there is already little or no bias to find. Instead, one should focus on making career options more friendly towards women's life plans so one doesn't unnecessarily lose them early. Quoting from a report on gender issues by the General Accounting Office and referring to the UC-Berkeley's "Family Friendly Edge" program, they suggest measures such as

"stopping tenure clocks for family formation and tenure-track positions seguing from part-time to full-time [...], adjusting the length of time to work on grants to accommodate child-rearing, no-cost grant extensions, supplements to hire postdocs to maintain momentum during family leave, reduction in teaching responsibilities for women with newborns, grants for retooling after leaves of absence, couples-hiring, and childcare to attend professional meetings [...], [Employer providing] high-quality childcare and emergency backup care, summer camps and school break care, [...] instruct[ions for] committees to ignore family-related gaps in CVs."

They kind of forgot to say that maybe most important is a decent maternity and parental leave to begin with, Sweden tells you how to.

Of course one should add it's not just women affected by this. Men who don't want to wait with having a family till they have job security and/or who have a partner not in the mood moving with them around the globe are in the present system also likely to drop out early. That's got nothing to do with hitting a glass ceiling. It's more like following the arrow that points to the open door.

Evolving Dimensions

That the space-time of Einstein's Special and General Relativity might not be fundamental plays a central rôle in our quest for quantum gravity. There are many possibilities how the fundamental structure of space-time may be different from the four-dimensional continuum; discretization and additional space-like dimensions are among those that have received the bulk of attention. No matter what the modification though, one has to make sure that deviations from the experimentally extremely well confirmed Standard Model of particle physics and General Relativity become important only at scales that we have not yet tested, typically at high energies or short distances.

The idea that space-time might not be higher-dimensional on short distances but instead be lower-dimensional has been around for some while, inspired by results from causal dynamical triangulation. In a paper last year, Anchordoqui et al proposed to examine the possibility of lower dimensionality at small distances for its phenomenology in their paper

Vanishing Dimensions and Planar Events at the LHC
Luis Anchordoqui, De Chang Dai, Malcolm Fairbairn, Greg Landsberg, Dejan Stojkovic
arXiv:1003.5914v2 [hep-ph]

Greg Landsberg gave a talk about this work on our last year's workshop on Experimental Search for Quantum Gravity (recording of the talk here). The basic idea is that the dimensionality of space changes with distance in such a way that it is 3-dimensional on scales we have tested it, lower dimensional on distances shorter than we have probed yet (about 1/1000 of a femtometer) and possibly higher-dimensional on distances larger than we can observe. The picture suggested is that of a (one-dimensional) string being knitted, and the knitted sheet (2-dimensional) being crumpled to a ball (3-dimensional). The authors dubbed this "evolving dimensionality." The merit of having a smaller number of space-like dimensions at small distances or high energies is that it improves the renormalizability of quantum field theories and esp. that of quantum gravity. (In contrast to additional dimensions which actually make the problem worse.)

The above paper as well as two recent follow-up papers, arXiv:1012.1870 [hep-ph] and arXiv:1102.3434 [gr-qc], looked at the phenomenological consequences of the evolving dimensions. Most interesting, they predict that at high energies the outgoing particles in scattering events should have an increased probability of being aligned in a plane. And the latest paper investigates the modification of the gravitational wave background. This modification is due to the early universe having been lower-dimensional if the idea is true, which would prohibit the propagation of gravitational waves. Both predictions are for all I know unique to this particular model.

But the question that springs to mind immediately is: What about Lorentz invariance? If one has a lower number of dimensions at short distances, these dimensions need to be oriented somehow relative to the four-dimensional continuum that must be reproduced at large distances. This orientation necessarily breaks Lorentz invariance. The problem is then that violations of Lorenz invariance are extremely tightly constrained already. I was thus curious to see how the model of evolving dimensions avoids these constraints.

The way this is achieved is that there is no model. Instead, it's in the authors words "not a concrete model, but rather a conceptual new paradigm." The papers offer pictures and analogies instead of a mathematical description of the new fundamental structure of space-time and the dynamics of quantum fields in it. The most recent paper addresses the issue of Lorenz invariance as follows:

"For random orientation of lower-dimensional planes/lines (see e.g. Fig. 2 ), violations of Lorentz invariance induced by the lattice become non-systematic, and thus evade strong limits put on theories with systematic violation of Lorentz invariance."

Unfortunately, this claim is not backed up by any argument and the figure does not represent a Lorentz-invariant random orientation. (The average spacings are approximately of the same size which is not boost invariant). From Causal Sets we know there are Lorentz-invariant 'sprinklings,' but these are sets of points and not distributions of planes. I also don't see from the picture if and how these planes end when they meet and it remains unclear how the length scales on which the dimensionality changes, supposedly a property of the space-time structure, is defined Lorenz-invariantly. Most problematic however is that the previous paper (arXiv:1012.1870) talked about the loss of energy into the background. This necessitates an interaction and that interaction should be described by an operator coupling the fields to the, oriented, background. I would then suspect this interaction falls among the already highly constrained Lorenz-invariance violations. It doesn't matter if these orientations average out on large distances if the effect that one looks for necessitates one is in a regime where one is sensitive to the distance it is not averaged out. This is very difficult to say though without a model.

However, in the recent paper on gravitational waves, one doesn't actually need Lorenz-invariance since one is concerned with cosmology and has a preferred frame - the restframe of the CMB - at hand anyway. So I wrote to one of the authors of the paper, Dejan Stojkovic from the University of Buffalo, who explained that they consider the model to be breaking boost-invariance but not rotational invariance. With that, the length scales on which dimensionality changes can be well defined without much effort. The question of Lorentz invariance violating operators however remains open. Dejan also readily admits that their new paradigm still needs work and explains how the first paper came about:

"I had this idea since 2003 while intensively working on higher dimensional theories. It crossed my mind that instead of making things more complicated at high energy (and hoping that the problems will miraculously disappear) we could instead make things less complicated - thus evolving dimensions (at short distances we have less dimensions, while at large distances we have more). However, I could not come up with a Lagrangian and would not dare to make it public.

Then at the meeting in Heidelberg, after diner and several beers, I told our friends, who intensively worked on extra dimensions, that the LHC is much more likely to find less rather than more dimensions, and after first 10 minutes of disbelief, they liked the idea and convinced me that in order to make a prediction rather than post-diction, the paper must go out NOW."

In summary: The idea of evolving dimensions is very interesting and makes predictions that are, for all I know, unique to this particular setting. At present it however lacks a mathematical model for the new fundamental structure and the dynamics of quantum fields in it.

This and That

• These are hard times for physicists working on supersymmetry. The LHC constrains the parameter space with so far no evidence for what has been the most popular model of physics beyond the standard model for decades. For details, check Peter's post on "Implications of Initial LHC Searches for Supersymmetry", Tommaso on "LHC Excludes SUSY Theories, Theorists Clinch Hands", and Resonaances on "More SUSY limits". Geoff Brumfield in Nature News titles "Beautiful theory collides with smashing particle data." Brumfield quotes Chris Lester, from the ATLAS collaboration: "We're painting supersymmetry into a corner," and Alessandro Strumia, a theorist at the University of Pisa in Italy:
  

  "Privately, a lot of people think that the situation is not good for SUSY. This is a big political issue in our field. For some great physicists, it is the difference between getting a Nobel prize and admitting they spent their lives on the wrong track."

  
  This week's Nature issue also has an editorial titled Dark Rumblings, comparing the LHC SUSY search to Michelson & Morley's search for the ether, arguing that "the negative results now coming out of the LHC should be just as stimulating as any positive findings." So if you've wasted 30 years of your life, don't forget negative results should be stimulating.


• The International Loop Quantum Gravity Seminar (ILQGS), a seminar series by telephone conference, now has a blog. Maintained by Jorge Pullin, it offers summaries of the talks in the seminar series.


• The Max Planck Society has a YouTube channel with short video clips about their research fields. While parts are only available in German, some videos are in English and worth checking out. The topics are as diverse as the Max Planck Society's institutes and of equally diverse quality. Interesting for example: GERDA, The Germanium Detector Array (on the search for neutrinoless double-β-decay), a bat catching a fly, or Honey, I shrunk Brad Pitt (on a video software for changing your waist and bra size.)

Societal Fixed Points

The extend to which one can construct a model for human society is a matter of dispute. Among the most common arguments why it might not be possible to build a testable model of the behavior of large groups of humans is that the elements of this model are conscious and self-aware and in contrast to, say, electrons, able to react to the proposed model. In the social sciences, this feedback into the system is called reflexivity.

There are many examples for this feedback indeed spoiling the predictions of a model. One of the best known is maybe the experiment conducted at Hawthorne Works from 1924 to 1932, where it was studied (among other things) how monetary incentives affect workers' productivity. Surprisingly, the productivity decreased. It has been suspected that this happened because the workers had heard of the study and were afraid an increase in their productivity would later result in lay-offs or a lowering of the base rate. Another example is Nobel-prize winners or other experts and authorities commenting on the economy. It is well known that consumer behavior is influenced by whether the outlook is pessimistic or optimistic, though in this case it's of course more difficult to identify the causes.

In any case, the argument that feedback necessarily spoils any model and thus such efforts are in vain has never made much sense to me. While this may be for some models, there's no reason a model can't remain unmodified under the feedback or that the feedback must be such to necessarily spoil the accuracy of the model. Take the previous example about a prediction affecting consumer behavior. If it's an optimistic outlook it (ideally) causes people to spend more. This doesn't spoil the prediction. On the contrary: it may turn it into a self-fulfilling prophecy. Or take the model of supply and demand. Most people know it, yet they don't go and buy the most expensive crap just to prove economists wrong. And why is that? Because they have no reason to. Instead, they believe everything is working in their favor as long as they continue to do what the model says they'll do anyway.

This of course lead me to wonder if there's fixed points in the set of models. There is arguably a trivial fixed point. That's the one when nobody knows of a model or nobody believes it, thus there's no feedback. But one could say it's not an attractive fixed point in the sense that it's unstable: The more successful a model is the more people will know of it and believe it. So, I'm posing the question to you: is there an attractive fixed-point? Because if there is one, that might be where we're going.

Interna

The German Winter is making place for Spring's first green, and our two lovely girls are now almost two months old. Lara and Gloria have outgrown the newborn diapers and we've sorted out the first set of clothes that got too tight. They have learned to suck on their fingers and are starting to focus on things. Since last week, Gloria is smiling generously while Lara prefers to stick out her tongue. At present they can neither grab nor hold any toys, and the only thing they seem to recognize are faces and milk bottles. They also haven't yet shown any intention of sleeping through the night

It has become apparent that the sisters are very different in character. Gloria is easily bored and wants to be entertained. Lara is content lying in her bed listening to music and playing with her fingers. Since neither Stefan nor I can recall the lyrics of children's songs and can't hold any tune anyway, the babies have an iPod player introducing them to essentials of German Culture. My favorite lullaby is clearly Kleine Taschenlampe Brenn (Glow, little flashlight) and the other day I caught Stefan humming La Le Lu while stuffing laundry into the machine. I've also rediscoverd forgotten childhood gems, such as Hey Wicky and Pippi Langstrumpf. Lara and Gloria both like Maja the Bee, but can't stand Captain Future.

The girls have made their first encounters with babysitters, and I am stunned by the variety of skin problems babies can have and by the amount of recommended alleged remedies. We meanwhile have a large selection of bottles, lotions and cremes for one or the other purpose that goes on this or that body part.

Meanwhile, I am still fighting with the health insurance. Every time I think I've finally filled out all forms and sent them all documents, I find another letter in our mailbox with another form or request for documents. The amount of paperwork that a pregnancy generates is simply amazing. The babies have also received their first mail ever: From the revenue office assigning them a tax number.

Five years Backreaction

Five years ago I wrote the first post for this blog. Since then I've moved from Santa Barbara to Canada and from Canada to Sweden. I've organized and attended multiple conferences and workshops, written a bunch of papers and reviewed a pile of books. Stefan finished his thesis and graduated, started a new job and moved to Heidelberg. We married, I got pregnant, and Stefan moved into a larger apartment. Presently, I am on parental leave and our little girls are almost two months old. During all this time, our blog has been a constant companion and we want to thank all our readers and commenters for the company!

Plagiarism 2.0

The German Defense Minister Karl-Theodor zu Guttenberg holds the title of Dr. jur. from the University in Bayreuth. He finished his thesis in 2006, at age 34, with more than 450 pages on the topic "Verfassung und Verfassungsvertrag: Konstitutionelle Entwicklungsstufen in den USA und der EU" (On the development of constitution in the USA and the EU). Guttenberg obtained the best possible grade, summa cum laude.

Two weeks ago, it turned out that big parts of his thesis were copied from other people's academic papers or newspaper articles. Since last week, one finds online a Wiki called GuttenPlag dedicated to collecting the copied paragraphs. The status is summarized in the below graphic (taken from mentioned Wiki):

Marked in black are pages on which plagiarized paragraphs have been found. Red are pages on which copies from several sources have been found. White means nothing has been found and blue is the table of contents and reference list that is not included in the search.

This eerily reminds me of a dissertation thesis I read last year. While the presented research was original, big parts of the text introducing the topic and explaining the relevance of the study were exact copies from other people's published review articles or research papers, including footnotes and references. The original work was cited in the text, but nowhere was it clearly marked the text was essentially an unauthorized reprint. Confronted with the evidence for his generous copying, the student first pointed out that he had cited the original papers. Yet, for a proper citation half of the thesis would have had to appear in quotation marks. Commenting on zu Guttenberg's "work," Volker Rieble, an expert on plagiarism summarized the core problem (as quoted in this Zeit article):

"Der Leser wird darüber getäuscht, dass ein bestimmter Absatz, ein bestimmtes Textstück, ein bestimmter Gedanke nicht vom Doktoranden zu Guttenberg, sondern von einem anderen stammt. Und das ist mit wissenschaftlichen Standards schlechterdings nicht vereinbar."

"The reader is deceived in knowing that a particular paragraph, a particular part of the text, a particular thought, did not come from doctoral candidate zu Guttenberg but from somebody else. This is not in accordance with scientific standards."

So you're not done with putting a citation somewhere, you have to make clear to the reader what is the extend of your borrowing. On further inquiry, the candidate whose thesis I had read - not a native English speaker - said with heartwarming honesty he had started writing the text but then found the other authors had said it so much better and clearer that the reader would benefit from using their words. The thesis was withdrawn and replaced prior to the defense. The candidate passed - as I said, his research was fine. Zu Guttenberg, whose copying work was only noticed after his defense, now has to await the University of Bayreuth's decision on whether he will be allowed to keep his title.

I know several examples where physicists, including myself on more than one occasion, have found paragraphs from their papers reappear in other people's papers. While the source was quoted somewhere in the text, the copied paragraphs were not marked as quotation. In all cases I know of, the people copying others' texts were not native English speakers.

Not a native English speaker myself, coming up with a well written motivation for a paper is a problem I can relate to. Otoh, at least I have an excuse for being grammatically challenged ;-) One should also note that some journals do offer editorial help with grammar and spelling. (Better read your proofs very, very carefully.) In any case, I'm bringing this up because already in a post some months ago, where I remarked upon the unreferenced spread of some of my pictures into other people's slide presentations, I was wondering if the possibility of copy-and-pasting is too much a temptation to resist or whether people just think nothing about it. The Times Higher Education for example recently reported that Chinese students admit to little or no idea about ethics:

"Research carried out by academics at Beihang University in Beijing found a startling lack of understanding of plagiarism and academic misconduct, with both students and staff admitting that they knew "very little" or "had no idea" about the norms of scientific ethics. [U]p to 10 per cent of the students surveyed said that they thought copying work directly from the internet should not be considered bad practice."

Even more depressingly, an increasing amount of college applicants seems to be lifting their "personal statements":

"[M]any applicants borrowed phrases from the same free website... In 234 applications to study medicine [from 50,000 applications to study medicine, dentistry and veterinary science at the universities of Oxford and Cambridge], candidates wrote that it was “burning a hole in my pyjamas at age eight” that sparked their passion for the subject."

So much about individualism.

The reason this depresses me is that these young people willingly give up the offered possibility of personalizing their application. The alternative is being reduced to numbers and, eventually, being assessed by some measure for success.

So, evidently, copy and pasting others' texts is becoming ever more common, and many people at least claim to not know it's unethical not to properly cite ones' sources. Where does this get us? I am wondering now if not time will come when a scientist can assemble parts of his paper from already published articles - a motivation from there, some literature review from there, summary of the method from there, of course marked as quotation - and just add the relevant new equations, tables, and figures. Does everybody really have to write the always same introduction in his own words (and then plagiarize himself in further publications)?

The Cosmic Neutrino Background

In the very early universe matter was dense and hot. With the expansion of space, matter cooled down which eventually allowed for the formation of nuclei and later atoms, molecules and increasingly large structures. Atoms could be formed when the average energy of electrons decreased to a value so small that ionization became improbable - an event called recombination. Photons, which prior to recombination were scattered on the free electrons, could then travel almost undisturbed. This happened at a temperature of about 1 eV, or some thousand Kelvin. Due to the continuing expansion of the universe, the photons from that time became redshifted, but are still present today. Their temperature is now at 2.7 K, and they have become famous under the name Cosmic Microwave Background (CMB). The temperature fluctuations in the CMB carry information about the structure of matter at the time of the photons' decoupling from matter. WMAP has measured these temperature fluctuations with great accuracy. (We discussed the CMB and some of what we have learned from it here, here, here and most recently here.)

The photons that we are so used to rely on for "looking" do not allow us to learn anything about the early universe prior to recombination. But we can try to see by other means. Neutrinos are well known for being weakly interacting, which is why they are so difficult to detect. But that they interact only weakly also means neutrinos ceased to scatter on the hot matter in the early universe earlier than photons. This happens at the typical energy scale for the weak interaction, at about 1 MeV or 10¹⁰K, after which the scattering of neutrinos and anti-neutrinos to produce an electron-positron pair became very improbable and, briefly after this, nucleosynthesis took place. Today, the temperature of the cosmic neutrino background, CνB, is about 10^-4 eV or 2 Kelvin* and it's all around us.

While we have not yet measured the absolute neutrino masses, but only have upper bounds, neutrino oscillations test for the differences of squares of masses. This allows us to conclude that at least some of the neutrino species must have cooled so much that their kinetic energy is smaller than their restmass, which means they are non-relativistic. This is interesting because these neutrinos will then clump in gravitational fields like that of our Milky way. As a consequence, the density of neutrinos on the path of planet Earth is roughly one to two orders of magnitude larger than the average density.

Still, these CνB neutrinos are very difficult to detect. But difficult is not impossible. Neutrino capture on tritium would, with some effort but presently available technology, yield a detection rate of maybe 10 CνB neutrinos per year [reference]. That would be enough to confirm the presence of the CνB, but to measure temperature fluctuations, with that procedure we'd probably have spend some million years doing nothing but gathering statistics, not to mention that tritium doesn't grow on trees. Alternative to tritium, it has recently been proposed to instead capture anti-neutrinos on Holmium, which, with some effort and some luck, might yield comparable detection rates. Direct detection of the CνB is the first step. Since the detection rate depends on the neutrino-density, it would not only confirm our theories about the creation of the neutrino-background, but give us information about the distribution of neutrinos in the gravitational field of our galaxy.

Sure, there's only so much you can learn from 10 neutrinos per year. But who knows what technological progress will bring? Half a century ago, the precision with which WMAP measured tiny fluctuations in a temperature that is tiny to begin with would have seemed a fantasy. Today it's fact. So here I am telling you that the CνB is out there, waiting for us to harvest the information it contains.

---

* It is (4/11)^1/3 times the temperature of the CMB. The conversion factor is partly due to neutrinos being fermions while photons are bosons, and partly due to the photons gaining in density, and thus temperature, when electron-positron pairs annihilate to photons while the opposite reaction becomes increasingly improbable. When this happened, neutrinos had already decoupled.

Book review: "A Brilliant Darkness" by João Magueijo

A Brilliant Darkness
The Extraordinary Life and Mysterious Disappearance of Ettore Majorana, the Troubled Genius of the Nuclear Age

João Magueijo
Basic Books (November 24, 2009)

The Italian theoretical physicist Ettore Majorana disappeared in 1938 at the age of 31. The reason for his disappearance and what happened afterwards were never clarified. His fate has inspired many books and movies, most of Italian origin, of which I haven't read or seen a single one. Thus, Magueijo's book was the first time I heard about the various theories of Majorana's disappearance, the leading ones being suicide, joining a monastery, or starting a new life in Argentina, due to depression, insanity, homosexuality or moral trouble with a research direction that Majorana might have understood earlier than everyone else would lead to the atomic bomb.

"... the [atomic] bomb, so much like a star in the sky, but so close to us that its brilliance amounted to darkness."

The more obscure theories feature various conspiracies, special forces, and/or aliens.

João's book, instead of listing all these theories, is a report on his following up on Majorana's fate. He has interviewed friends and relatives, seen the movies, read the books, visited the places. Woven together with his travels are explanations of the physics Majorana has been working on and the historical circumstances. The physics is explained on a level understandable without previous knowledge and covers atomic physics, β-decay, parity, chirality, neutrino-oscillation, (neutrinoless) double β-decay and the experiments behind all this. The reader is confronted with the difficulties scientific research had to cope with under Mussolini and Hitler, and gets to meet Majorana's contemporaries, among others Fermi, Heisenberg, Dirac and some radioactively contaminated fish.

João does not put forward his own theory or presents a solution to the mystery. Instead, he uses Majorana's life and unknown fate to get across some science and touch upon questions like the role of scientists in our societies, the clash between pragmatism and idealism, the ignorance of academics, the balance between competition and collaboration, and the influence of personal life on ones research. There's a lot in that book to make you think and João doesn't even attempt to think in your place.

The book is well written in a light-hearted style despite the dark topic, and the main flavor is sarcasm. João, let me remind you, is the one who famously suggested in his first book that the "M" in M-theory stands for "masturbation." In his book on Majorana, string theory makes an appearance as as an example for "the fad of postulating thousands of unnecessary particles," and João doesn't hesitate to speak his mind on all and everybody: Fermi, so João writes, "did lack imagination," "when [Dirac] spoke the outcome was... logically crafted insanity," and Cambridge (UK) is "that ivory tower of lunacy." The book is also interspersed with paragraphs that seem to have gotten there by random association, my favorite one is:

"Saying that we live in an odd world is often an understatement. I once had a random conversation on a Toronto street that derailed into the most sublime insanity. After a few minutes of pleasant platitudes, my casual acquaintance, out of the blue, revealed that "they" had implanted radioactive isotopes in his testicles. Being high-minded, he refrained from ejaculating, lest he might contaminate the entire universe."

and later he describes meeting an old friend at a book fair in Buenos Aires, an event that doesn't have any apparent relevance to Majorana's story. There's more side-tracks of this sort. One might say the book is also a book about João. If you decide to read it, you'll either love or hate it, but either way you'll very likely finish reading it.

A Peek Inside the Perimeter Institute

I almost forgot! Last year, the Canadian Association of Physicists' journal "Physics in Canada" published an issue on Perimeter Institute with a preface by Neil Turok and Rob Myers, and feature articles by PI researchers from all groups. It appeared during the summer, but then it took several months for the articles to appear online, by which time I was distracted by other things and forgot to tell you about it. The articles cover a great selection of topics on a level comparable to that of Physics Today. There is for example Alex Buchel et al on AdS/CFT and the Quark Gluon Plasma, Urbasi Sinha et al on an experiment testing Born's rule (which we previously discussed here), Willam Unruh on Analog Gravity and Black Holes, and Lucien Hardy and Rob Spekkens on Why Physics Needs Quantum Foundations. Just to mention a few. You find all the articles in PDF form here. It's very recommendable - enjoy!

Book review: “The Shape of Inner Space” by Yau and Nadis

The Shape of Inner Space: String Theory and the Geometry of the Universe's Hidden Dimensions
Shing-Tung Yau and Steve Nadis


Yes, I said I have no intentions reading the book. But then I was offered a copy for free. And, since I had it anyway, I could as well read it, no?

“The Shape of Inner Space” is a curious mixture of Yau’s autobiography, a crash-course in differential geometry, and physics-themed popular science, sandwiched between an introduction to the history of geometry and philosophical considerations about the beauty of mathematical truth. The string that runs through the book and weaves it together are Calabi-Yau manifolds. Shing-Tung Yau, the “Yau” in “Calabi-Yau,” has spent pretty much his whole life on these manifolds and won the Fields Medal in 1982, among other achievements, for his proof of the Calabi conjecture. So the reader learns first hand from the world expert. Steve Nadis is a popular science writer, and the two have joined forces to produce the book.

The result is interesting and also courageous.

After the introduction, it follows a brief history of geometry. From Pythagoras and Plato over Euclid, Descartes, Gauss and Euler to Minkowski, Riemann, Einstein, Kaluza, Klein and, of course, Calabi. As we come closer to the 21st century, we learn about the geometrization of physics and its successes. To move on beyond Platonic solids, the reader is introduced to mathematical lingo in a rapid fire treatment. It starts with the innocent concept of derivative and integrals. From there it goes on to partial derivatives, curve integrals, non-linear partial differential equations, manifolds (differentiable, compact, orientable, product of), complex numbers, metric (in n dimensions, hermitian), parallel transport, geodesics, curvature and Ricci curvature, groups, tangent spaces, fibre bundles, exotic spheres, homeomorphic diffeomorphisms, harmonic equations, Betti numbers, Chern classes, holonomy and cohomology, Ricci flow, Riemann surfaces, Kähler manifolds and of course Calabi-Yau spaces. Just to mention a few. If you're afraid of math, this book is not for you.

In the later chapters follow the contemporary topics, and the connection to string theory is established. The reader learns about the Dirac equation, Yang-Mills theory, mirror symmetry and the Seiberg-Witten equations. We come across Yukawa-couplings, correlation functions, black hole information loss, moduli and the landscape problem. We meet familiar names like Hawking, Penrose, Guth, Strominger, Kachru, Witten, Greene, Gross, Susskind, Vafa, Giddings and more. Nadis has interviewed many researchers in the field and the text is frequently supplemented by quotations from these interviews (and other sources). One might find it an expression of laziness (or maybe cowardice) to export explanations and opinions into quotations from other people. But I found it very readable and interesting to hear the researchers’ comments and explanations of their work, and that of others, in their own words. I liked that a lot.

The mathematical and physical explanations are accomplished basically without equations (though there are a few examples) and without formal definitions. Sometimes the text is accompanied by figures that I found very helpful and well done, but figures only get you so far to understanding six dimensional spaces. Now all the used concepts are explained somewhere, and I was familiar with most of the terminology before reading the book anyway. But I suspect if you don’t know anything about field theory, differential geometry, and topology, “The Shape of Inner Space” is a very heavy read.

With use of the introduced mathematical concepts the reader then learns what Yau proved, what his colleagues proved and how the field has evolved within the last some decades. Then the authors explain how the connection to string theory came about and how this intersection of physics and math has been fruitful for both sides. That I found indeed the most interesting aspect of the book: The interrelation between mathematics and physics and the mutual benefit for both sides. Yau writes:

“[I] like to position myself at the interface between these two fields, math and physics, where a lot of interesting cross-pollination occurs. I’ve hovered around that fertile zone since the 1970s and have managed to get wind of many intriguing developments as a result.”

However, the book is very focused specifically on the cross-pollination between differential and algebraic geometry and string theory that has sprung from Calabi-Yau spaces. It is a pity there was not more about the recent and not-so-recent history of the math-physics exchange in a broader sense.

Towards the end of the book, after a somewhat bizarre interlude about the way you would die through false vacuum decay, we then find a chapter on experimental tests of string theory. Yau is a mathematician and takes the point of view of an interested outsider. His main interest is mathematical truth, and if physicists with their methods can help mathematicians discover previously unknown relationships, then what does it matter if the physics eventually turns out to be a description of reality? But one or the other reader might care.

“At the end of Dorothy’s adventures in the Land of Oz, she learned that she had the powers to get back home all along. After some decades of exploring the Land of Calabi-Yau, string theorists and their math colleagues (even those equipped with the penetrating powers of geometric analysis) are finding it hard to get back home – to the realm of everyday physics (aka the Standard Model) – and, from there, to the physics that we know must lie beyond. If only it were as easy as closing our eyes, tapping our heels together, and saying “There’s no place like home.” But then we’d miss out on all the fun.”

Thus, in the chapter “Back to the real world” we learn about possibilities to test string theory in the early universe, by bubble collisions and their relics, by cosmic strings or – in the case of large extra dimensions – at the LHC. (I guess this is pretty much the last time a popular science book will talk about the latter possibility.)

Unfortunately, it is not very clearly pointed out that all these tests are tests not of string theory itself but of string theory inspired phenomenological models. Finding such evidence would certainly be a boost for string theorists, but not finding it doesn’t need to bother them either. A quotation by McAllister states it very carefully correct: “It’s possible that string theory will predict a finite class of models, none of which are consistent with the observed properties of the early universe, in which case we could say the theory is excluded by observation.” Yes, it is possible. But at the moment it seems like there’s a string theory motivated model to explain whatever the data will be.

Yau and Nadis avoid commenting on the controversy about the usefulness of string theory as a description of reality. On the landscape problem Yau writes “It’s fair to say that things have gotten a little heated. I haven’t really participated in this debate, which may be one of the luxuries of being a mathematician. I don’t have to get torn up about the stuff that threatens to tear up the physics community.”

“Critical treatments of [string theory], such as The Trouble with Physics and Not Even Wrong” are mentioned in the passing, decorated with quotations from Henry Tye saying “string theory is too beautiful, rich, creative, and subtle not to be used by nature,” and Michael Atiyah letting us know that “even if we can’t measure it experimentally, [string theory] appears to have a very rich… mathematical structure. [String theorists] are onto something, obviously. Whether that something is what God’s created for the universe remains to be seen. But if He didn’t do it for the universe, it must have been for something.” (Like, maybe the multiverse?)

It then follows some elaboration on beauty and mathematical truth, and its relevance for physics:

“Of course, if beauty is going to guide us in any way […] that leaves the problem of trying to define it […] There’s no doubt that a blind adherence to mathematical beauty could lead us astray, and even when it does point us in the right direction, beauty alone can never carry us all the way to the goal line. Eventually, it has to be backed up by something […] more substantial, or our theories will never go beyond the level of informed speculation, no matter how well motivated and plausible that speculation may be.”

But Yau and Nadis remove themselves from the debate about physical relevance by focusing on the mathematics:

“Whereas the final proof in physics is in experiment, that is not the case in math… If the mathematics associated with string theory is solid and has been rigorously proven, then it will stand regardless of whether we live in a ten-dimensional universe made of strings or branes.”

And that is what the book is about – it’s a book about the mathematics of Calabi-Yau spaces, not more and not less. Just so you know what to expect should you consider buying “The Shape of Inner Space:” It’s not, in the first line, a book about string theory and certainly not about quantum gravity*. It is a book about a special kind of manifold and the interaction between physicists and mathematicians it has brought.

The book is generally well written, though I found the writing style over long stretches somewhat uninspired. Many pages it goes along the lines that soandso wrote this paper on this, and then soandso wrote a paper on that, and then a student of soandso wrote a paper on this and that, and so on. Also, I found it somewhat disturbing that in several places technical terms are used that are only introduced in later chapters, sometimes with, sometimes without, mentioning of the later explanation (metric and entropy for example). The book has a glossary, but if hadn’t known anyway what they were talking about I’d have found it a quite annoying break in the reading flow.

The book is also discontinuous in the level of explanation. Over many pages it reads almost like a review paper on Calabi-Yau spaces, summarizing who proved what when by which method. And then there comes the occasional pop-sci explanation. Just to give you an impression, here’s a quotation from a randomly chosen page (133):

“The presence of those [covariantly constant] spinors helps ensure the supersymmetry of the manifolds in question, and the demand for supersymmetry of the right sort is what pointed Strominger and Candelas to SU(3) holonomy in the first place. SU(3), in turn, is the holonomy group associated with compact, Kähler manifolds with a vanishing first Chern class and zero Ricci curvature.”

(That supersymmetry partners bosons and fermions is btw explained only some pages later.) The level of the pop sci explanations are for example that of an exchange particle mediating an interaction by the common analogy to a ball being thrown, or for quantum foam by analogy to the British railway. (“The geometry, in other words, would be undergoing shifts so violently it hardly makes sense to call it geometry. It would be like a rail system where the tracks shrink, lengthen, and curve at will –a system that would never deliver you to the right destination and, even worse, would get you there at the wrong time.”).

The impression I had was that Yau wrote a draft, and Nadis then sprinkled pop sci explanations and quotations on it.

Taken together, I enjoyed reading the book more than expected. It is a very comprehensive summary of research I have a peripheral interest in, and Yau and Nadis have presented it very nicely, so I learned some relations that previously hadn't been clear to me. I was surprised though that the AdS/CFT correspondence is only briefly mentioned and its recent applications are not discussed at all. I'd have found it relevant to the question of what string theory is a theory of. And, there's no explanation of what is actually plotted in the omnipresent pictures of Calabi-Yau spaces you find for illustration all over the place.

Reading the book I couldn't help wondering what audience it is aimed at.
Readers should at the very least have read a fair share of popular physics books because they will not get an introduction to general relativity and quantum mechanics, not to mention quantum field theory, though these are essential to understanding big parts of the book. Black holes, entropy, the standard model, dark matter, inflation etc are explained with only a few sentences each. This, I will admit, was a great relieve to me because I’ve read more than enough stories about quantum pets and suicidal astronauts plunging into black holes. I’m just saying you better bring that knowledge along because otherwise you’ll miss big parts of the story. And, given the mathematical rapid fire treatment, the reader should at the very least have a high school exam, preferably a few semesters math in addition.

In summary, the book might be interesting for you if you have some, though not necessarily expert knowledge in math and physics. “The Shape of Inner Space” will give you a good impression about the state of the art, the history, and a glimpse on the possible future of research on Calabi-Yau spaces. You will learn about the interaction between math and physics it has inspired, and it will give you opportunity to ponder eternal truth and beauty in mathematics, and its relevance for Nature.

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* In the introduction it is made clear that “Because of our focus on so-called Calabi-Yau manifolds and their potential role in providing the geometry for the universe’s hidden dimensions – assuming such dimensions exist – this book will not explore loop quantum gravity, an alternative to string theory that does not involve extra dimensions […]” And that's the first and last time alternative approaches to quantum gravity are mentioned.